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WELLCONTROL CERTIFICAflON PROGRAM

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PTTCO WELLCONTROLMANUAL

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PAT'TAYA,("1AE;

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7"t April 2077

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COMMEilNt AND INTRODUCTIOT{ TO

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TRAIT{II{G MATIUAT

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PTTGoLtd management and team

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are dedicated to providing a high standard of training. to deliverthe best and cater to our ctient,s demands and expectationsin the areas of drilling and weft interventions. As a group' we are obligated

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The contents of this manual have been compiled and prepared in a way to try and herpthe course participant to gain full understandingof instruction materiarsin therwcF/fADC certification program. we befievethe knowledgegained at our course, where participants wourd bring back with them into the work place where the training we trust wilf help provide additional informationto assist, while conductingtheir operations in the working environment.

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certirication course inrhairand, Brunei, singdpore, vietnam,

Sararit pongpitak(Daeng) President,PTTCOLtd. 54/3 Moo 13, NavaminZO, Bangkok!O24O,Thailand Mobite:+6681920 3318 Tel: +662 947 g25g +662 510 3808, +662 S1O 6195 .Fq: [email protected] www.pttco.org

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TABLEoF coNTENTS

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chapter 1

ANDCALCUIATION : BASIGTERM,DEFINITIONS

Chapter2

CALCUTATION : WELLVOLUME

ghapter3

: SLOWpUMPRATE,LEAKOFFTESTANDMAASP

Chapter4

PRESSURE IN FM)ROSTATIC : REDUGTION

chaptet5

PROOEDURES : KICK& sHUT-lN

Ghapter6

DATA : SHUT-IN

Ghapter7

OFGASINFLUX : BEHAVIOR

Ghapter8

MEIHODS : WELLKILLING

Chapter9

OPERAIION lN WELLKILLING : PROBLEM

Ghapter1O

EQUIPMENTS : WELLCONTROL

Ghapter11

: SUSEAWELLCONTROL

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Appendixes ANDCALCUIATION : BASICMATHEMATICS WELLKILLSHEET(APlUt{lTS) BOPVERTICAL : SURFAGE WELLKILLSHEET(APIUNITS) : SUBSEABOPVERTICAL

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SHEEInPl UNITS) : FORMULA

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Well ControlManual Chaptert

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INFORMATION GENERAL

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The functionof well controlcan be sub-dividedinto 3 phases,namely primarywell well controlandtertiarywell control. control,secondary

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himary Well Control

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PrimaryWellControlis hvdrostaticpressureprovidedby drillingfluid morethan pressure formationpressure but lessthanfracturegradientwhiledrilling.lf hydrostatic is pressure, lessthanreservoir reservoir fluidmay influxintowellbore. Thissituationis called"Lossof PrimaryWellControl".

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pressure Notonlyis hydrostatic morethanformationpressure, but alsohydrostatic pressure must not exceedfracturegradient.lf yourmud in holeis too heavycausing problem(maybe partiallylostor total youwill facewith losscirculation brokenwellbore, fiostcirculation). Whenfluidis losingintoformation,mud levelin well borewill be pressure. you decreased that will resultin reducinghydrostatic In worstcasescenario, will losethe primarywell controlandwellboreinfluxor kick will enterintowellbore.

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pressure pressureis normally Typically, slightlyoverbalance of hydrostatic overreservoir primarywell controlthat desired. Youmust keepin mindaboutthe basicof maintaining youmustmaintainholewith drillingfluidthat will be heavyenoughto overbalance formationpressure but notfractureformation.

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Note:BHPcreatedby hydrostatic columnof drillingfluidis the primarywellcontrolin drilling.

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lf BHPis morethan FP(formationpressure), this situationis called"Overbalance". lf BHPis equalto FP(formationpressure), this situationis called"Balance". lf BHPis lessthan FP(formationpressure), this situationis called"Underbalance".

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Secondary WellControl

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Whenprimarywell controlfailed,it causeskick (wellboreinflux)comingintowellbore.

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Therefore, thissituationneedsspecialequipmentwhichis called"BlowOutPreventer" (BOP)to controlkick.We can call that 'Blow Out Preventer"or BOPis SecondaryWell

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controlkick suchas driller'smethod,wait and weight,Concurrent, Volumetric, lubricate

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and bleedand bull heading.Withoutwellcontrolpractices for usingBOPs,it willjust be

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onlyheavyequipmenton the rig.

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Control.Pleasealsorememberthat BOPmust be usedwith specificprocedures to

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TertiaryWell Gontrol

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(BOP)performing differentapplications. Thereareseveraltypesof "BlowOutPreventer" wellcontrolfailed?lf well is flowinghow do Canyou imagineif primaryandsecondary we dealwith it? Forthis situation,you must useTertiaryWell Control.

TertiaryWell Controlusesspecificmethodto controlwell in caseof failureof primary are examplesof tertiarywellcontrol: well control.Thefollowings andsecondary

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Drillreliefwellsto hit adjacentwellthat is flowin$and kill the wellwith heavy mu d .

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Dynamickill by rapidlypumpingof heavymud to controlwellwith Equivalent Density(ECD) Circulating Pumobariteor gunk to pluBwellboreto stopflowing Pumocementto PluElwellbore

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BasicTerms,Definitions,and Calculation

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PRESSURE

Definitionof Pressure Pressure is forceexertedper unit area.In APIunit pressure is expressed in poundper s q u a r ei n ch(p si ). Forcein Pound

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Pressure- Pound per SquareInch (psi)

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1 unit area(sq.in)

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HYDROSTATIC PRESSURE

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pressure(HSP)is the pressureexertedby a column of fluid at rest.This Hydrostatic pressure dependsonlyon the densityof the fluidand its trueverticaldepth.

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HSP

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0.052 x MW x WD

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pressurein psi,MW is fluid weightin ppg,TVDis In API unit,whereHSPis hydrostatic tnueverticaldepthin feet,and 0.O52is a conversion constant(psy'ft./ppg).

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The0.052conversion factoris derivedas follows:

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! cubic foot contains7.48 US gallons f pp€ hasa weightequivalentto 7.48 pounds 7 cubic foot hasa basearea of ! squarefoot Square 7 squarefoot equalsto 744 square inches Therefore,the pressure exerted by a fluid of 7 lnch foot heightover the area of its basewouldbe 7.48 + 744 = O.O52pound persquareinch(psi). Ihis ts the same as saying,the PressureGradient of 7 ppS,fluid = O.O52psi/ft.

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re Effects: HydrostaticPressu SingleFluid Density

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1l-0 ppg

HydrostaticPressure= O.O52x 7! x 8,OOO = 4,576 psi

9,000ft.

Hydrostaticpressureis affectedby densityof fluid and its verticaldepth:

Density Depth,TVD Hydrostatic Pressure (psi) (ft.) @pA

MW (ppg)

9.O

8,OOO

3,744

70.o

9,OO0

4,680

70.5

lo,ooo

5,460

ps

75,OOO

9,750

Differentfluid densitiesin the well: HydrostaticPressure(HSP)at different fluid columns (in Annulus) HSPof fluid columnt = O.O52x 7Ox 3,5OO= \82O psi HSPof fluid alumn 2 * O.052x 9 x 4,OOO = 7,872 psi HSPof fluid column 3 = O.O52x 7! x 5OO = 286 psi

7,500ft.

Total HydrostaticPressure = !,82O + !,872 + 286 = 3,978 psi (at 8,OOO'TVD)

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DEPrH(MD) DEPTHCrVD)VSMEASURED TRUEVERTTCAL The hydrostaticpressure in the well is calculatedbasedon the TrueVerticalDepth WD).This is due to gravitypullingstrai$ht from the downor verticallydown.Therefore, given diagram,the hydrostaticpressureat by using the bottomof the well is calculated the verticaldepthof 1O,000ft. (WD). pressure= 0.052x 10 x 10,000 Hydrostatic = 5,2OO psi The MeasuredDepth(MD) is the depth alongthe well path if well drilleddirectionally. Thisdepthis derivedfrom the sum of drill stringslengththat the drilleraddsor makes whlledrilling.Thismeasureddepthis usedfor the wellvolumecalculations. connection 1,.4

GRADIENT PRESSURE

gradientis pressure of fluidof knowndensitymeasuredovera $ivenunitdepth. Pressure Sampleof PressureGradient Freshwaterhas a densityof 8.33 pp€,in a foot columnit shouldexerta pressureof (0.052x 8.33 x 1) = 0.433 psi. We then call pressuregradientof freshwater= 0.433 psi/ft' of Saltwaterhasa densityof 8.94 ppg,in l foot columnit shouldexerta pressure = (0.052x 8.94 x 1) 0.465 Psi. We then call pressure$radientof salt water = 0.465 psi/ft. Typeof Influx(Kick)Gradients = Gas Mixtureof Gas,Oil,Water = = SaltWater

lessthan 0.156 psi/ft.(lessthan 3 ppg) 0.156 - 0.465 psi/ft. ( 3 - e PPg) 0.465 - 0.520 psi/ft. ( e - 10 ppg)

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HOLEPRESSURE BOTTOM

exertedat the bottomof the hole' (BHP)is the sum of all pressures Bottomholepressure In $eneral,bottom Bottomhole pressurewill be varieddependingon the operations. hole pressurecan be expressedas follows: BHP - HydrostaticPressure+ SurfacePressure+/'Dynamic Pressure pressureis the pressureexertedby drillingfluid,the surfacepressureexerted Hydrostatic ni tne shut in pressurewhen well was closedby BOPand the dynamicpressureis the pr"..ut" exerted due to fluid movement(i.e. Annular FrictionLosses)and pipe movement(i.e.Surgleand Swab). 1.5.1 BHPwhen not circulating = 0.052 x PPgx TVDwell L.5.2 BHPwhiledrillingor circulating = (0.052x ppg x TVDwell)+ AnnularFrictionLosses(AFL) 1.5.3 BHPwhiletriPPingin hole = (0.052x ppg x TVDwell)+ Surgepressure L.5.4 BHPwhiletrippingout of hole = (0.052x ppgx TVDwell)Swabpressure

1.5.5 BHPwhenwellwas shut in when the well wasshut in due to kick and the Bit on bottom,the bottomholepressureequalsfo the Formationpressureatthe initial shutin sta$e.The bottomhole pressurecan be determined by: Total HSPin Drill strin{, BHp = HSpof mud in drillstring+ srDPP = (0.052x pp{XTVDwell) + S|DPP TotalHSPin Annulus BHP = HSPof mud in annulus+ HSPof influx + SICP = (O.O52x pp| x ft. columnof mud) + HSPof influx + SICP Note;

The correctBHPdeterminedon the annulusside should be basedon the assumptionthat the influx is not mi$ratin$upward.

W e l lC o n t r o lM a n u a l Drilline

Well GontrolManual Chaptert

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Bottom HolePressureRelationship actingon the bottomhole.We Thebottomholepressureis the sum of all the pressures candescribethe statementbeforeas the followin$equation; Bottom HolePressure(BHP)= SurfacePressure(SP)+ HydrostatlcPressure(HSP) of bottomholepressure. the relationship Theimagebelowdemonstrates

Pressure Surface tSP)

r.J BottomHolePressure {BHP) BHP=SP+HSP SurfacePressure(SP) = Bottom HolePressure(BHP) - HydrostaticPressure(HSP)

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Well ControlManual Ghapter1: BasicTerms,Definitions,and Calculation

PAG E 8of33

gradientof water(0.465psi/ft) is normalpressure We assumethat formationpressure = 3720 psi.Thefirst case: = psi/ft so formationpressureat 8000' TVD 8000 ft x 0.465 gradientso Surface columnis waterwhichis equalto formationpressure Hydrostatic psi (SP) Pressure is equalto 0 Thesecondcase:BHPis to be watergradientbutfluid columnis oil (0.35psi/ft)whichis in orderto balanceBHP,we lowerdensitythanwatergradient(0.465psi/ft).Therefore, = needSurfacePressure(SP)of 920 psi (SP 3720 (0.35x 8000)). Thethirdcase:BHPis to be watergradientbutfluidcolumnis gas(0.1 psi/ft)whichis in orderto balance evenlowerdensitythanwatergradient(0.465psi/ft).Therefore, = (SP)ot 2,920 psi(SP 3720 (0.1x 8000)). BHP,we needSurfacePressure Accordingto the example,SurfacePressure(SP)will compensatethe lackof hydrostatic pressure(HSP)in orderto balanceformation pressure(FP). EFFECTS SURGE& SWABPRESSURE exertedon are additionalpressures surgepressures pipe hole.As in the of the the movement well by the andthefr iction p i p ei s r u ni n toh o l emu di s d i splaced effectof the mud followin$up aroundthe bit andthe surgebelow bottomholeassemblycausesa pressure and cancauselostcirculation the bit.surgepressure fracture. formation to the is the reductionin the hydrostatic Swabpressure pressure whichmayoccurat anypointbelowthe bit. is causedby an upward of pressure Thisreduction in the holewhichcreatesa drill string movementof suctioneffectbelowthe bit.Thesuctioneffectis createdbecauseit is difficultfor mud to fall belowthe Themaximumswab b i t a s r ap i d l ya s th e p i p ei s p u l l ed. pressureis occurredwhen the bit isjust liftedoff bottom.Swabcan reducethe BHPsufficientenoughto allowinfluxflowsintothe well bore.

STIRGE

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for Surgeand Swab 1.6.1 Conditions may occurif: Swaband surgepressures . and gel strengthis high. Mudviscosity o Pipemovementis fast. . T h i ckw a l lca ke(mu dcakeon wellbor e) . r a gainstBHAis small. A n n u l acl r e a ra n ce o is balledup. B i t,re a me ro r sta b i lizer

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Well GontrolManual Ghapter1: BasicTerms,Definitions, andCalculation L.6.2 Swab indicationat surface Swab can be detected by using 'TRIP SHEET", by checkingif the hole takes a properamountof mud when pullingthe pipeout of holeor if the rightamountof mud return (not over return) when Swnbbing in a kick runningthe pipe in hole due to the pipe metal displacesthe mud in the hole. Swab is also clearlyindicatedat surfacewhile trippingout pipeby: . Overpull. . No dropin mud levelin the annulus. o Risein mud levelin annuluswhendrillstringis beingpulledout of hole. Pullingout the pipe througha horizontalreservoirsectionwhere the formationhas a highpermeability cancompoundthe amountof fluidswabbedin. EquivalentMud Weight(EMW) The equivalentmud weight can be definedas the total pressureof a mud column exertedat a givendepthexpressedin poundper gallon( ppg) equivalent. An exampleof EMWis fracturemud weightin ppg(Maximumallowablemud weight).

g npte ConvertShoeFracturepressure 3858 psi ( Shoe TVD45OOft) into Equivalent tilud WeiSht(EMW): Maximum allowablemud weight 3 8 58psr

(0.0s2x 4500ft)

= 16.49ppg

Answer:Maximumallowablemud weight = !6.4 ppg(roundeddown)

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BasicTenns,DEfinitions,and Calculation

DENSIW(ECD) CIRCULATING EQUIVALENT

in ppg whichwould The equivalentcirculatingdensity,ECD,is a calculatedmud wei$ht pressure generatehydrostaticpreisureat a point in the well bore,equivalentto the total from the sum of the from ail sourcesat that point.whire driiling,the ECDis carcurated pressures andthe annularpressurelossesin the well' hydrostatic ECD(ppg)-

Mu d H yd rostattcpTessur elAnr utlar pr .essuTelosses ( 0.052xTVD well)

or ECD(ppg) - Origtnal MW

Attrutlar pr es slrre losses (0.052 xTVD well)

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Mud in use 1o ppg

Friction Losses in Annulus 120 psi

10,000 ft.

Bottomhole Pressurein static condition = ilO,0OO x !0 x O.O52 = 5,2OOpsi

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CircuI atin!, (dynamic) bottom hole pressure = 5,2OO+ 72O = 5,32Opsi

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EquivaIent Circut atin{, Density(ECD) 5,320 0 . 0 5 2x 1 0 , 0 0 0 = 7O.23pp€ or Equ ivalent CircuI atin$,Den sity (ECD) t20 :10+( 0 . 0 5 2x 1 0 , 0 0 0 = 7O.23PP€

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spm of a well with well Example:Calcutatethe BHPwhen circulatin$,72pp€ mud at 45 lossesof 72O psiat 45 spm,bit nozzlespressurelossesof ft, annularpressure TVDSOOO 2O0Opsi at 45 sPm. = 72 pp€,x0.052 x SOOO ft Mud hydrostaticpressurein annulus = 4992 psi = 4992 psi+ 72O Psi= 5772 Psi Answer:BHPat 45 sPm at constantpump spm)' (Mud density and APLmay affect BHPwhile circutatinS,

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PRESSURE CIRCUI.ATING

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pressure is producedby mud pumpwhichis requiredto or pumppressure Thecirculating overcomethe frictionbetweenthe drillingfluid and whateverit contactsas it moves system.This pressurewill be at hi$hestat the pump discharge throughthe circulation the frictionlossesin and will graduallyreduceto zeroat the mud returnline.Generally, intofour distinctparts: systemare considered the circulation

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rotaryhose,swiveland Kelly.) Frictionlossin surfaceequipment(standpipe, Frictionlossin the drillstring,bothin drill pipeand drillcollars. or jets. Frictionlossin bit nozzles Frictionlossin annularspaceoutsidedrillstring.

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or PumpPressure: Pressure Girculatin$

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= FL (standRipe;* FL lorlllstrlng) + FL (bItnozles)+ FL (annulus) WhereFL denotesFrictionLoss.

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FL. Drill tir,nt

CirculatinSPressure= 2,5OOpsi

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Surfacelines, Standpipe,Kelly hose 50 psi 45O psi Drill pipe 7O0 psi Collars 7,7OOpsi Bit nozzles 200 psi Annulus Total Friction Losses

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Fxample:

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2,5OOpsi

Well GontrolManual Ghaptert

BasicTerms,Definitions,and Calculation

Svstem in the Ri{ Circulating LossComponents Pressure Frictional FrictionalpressureLoss:FrictionalPressureLossis pressurelosscreatedby fluid flowing gelstrength)' viscosity, throughthe flow path.lt is a functionof fluidproperty(density, pressure of flow path(holesizeldrillstringsize).Frictional velocityof fluid,characteristic loss,higherpump lossaffectson pumppressurebecausehigherfrictionalpressure

!

pressure is requiredto maintainthe pumprate. losscomponentin the drillingri$system' the pressure In orderto clearlydemonstrate pressure lossacrosseachflow pathof drillingfluid in the the diagrambelowdescribes sYstem. total rigcirculation Parametersthat affect pump pressureare as follows: 1. Fluidpropertiesespeciallymud weight,viscosity,gel strengthand yieldpointaffect gelstrengthandyield Thehigherthe mudweight,viscosity, directlyon pumppressure. to maintainpumprate. point,the higherthe pumppressurerequirement Thisis a basic 2. pump rate is anotherfactorthat affectsdirectlyon pumppressure. is required. conceptsuchthat whenhigherpumprateis needed,higherpumppressure 3. Holesize/drillstringsize:Smallerinternaldiameterof bothholeanddrillstring,higher velocityof fluidflow is createdat samepumprate.Hi$hervelocitycreatesmore is requiredin orderto maintainpumprate loss.Highpumppressure frictionalpressure becausethereis additionalpressurelossdueto smallerholesizeand drillstrin$' 4. BHAand Bit Dueto smallinnerarea,BHAand bit can causemajorityof pressure and bit nozzleselectionare criticalfor hydraulic loss. Hence,BHAdesign/selection design. losswill occur. lt meanswe 5. Well Depth:Thedeeperof the well is,the morepressure needmorepumpcapacityto achievethe drillinggoal. Depthof the well is basedon on howto Thispartwill influence the earthby $eologists. geological targetsunderneath of the wells. objectives selectthe properrig capacityin orderto meetsoundhydraulic

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PAGE lil of 33

FORMATION PRESSURE

Formationpressureor porepressureis the pressureexertedby naturallyoccurringfluids trappedin the porespacesof the formation.Thesefluidsincludewater,oil and gas.This pressurecan be affected by the weight of the overburden(rock layers)above the formation,whichexertspressureon bothgrainsand porefluids.lf porefluidsare freeto moveor escape,the grainslosesomeof theirsupportandwill moveclosertogether.This processis calledcompaction. Theformationpressure is dividedintothreecategories: In termsof gradient, o Subnormalpressure ( Gradient< 0.433 psi/ft) o (0.433< Gradient<0.465 psi/ft) Normalpressure . Abnormalpressure (0.465< Gradient< 1.0 psy'ft) UnderstandinEl AboutFormationPressure Formationpressure is the pressure of fluidcontainedin porespaceof rockand thereare pressure threecategories whichare normalpressure, of formation abnormalpressure andsubnormalpressure. 1- NormalPressure:Normalpressureis the hydrostaticof watercolumnfrom the surface to the subsurface formation.Theconcentration of salt in wateraffectsthe normal pressure. Highersaltconcentration in water,higherspecificgravityof waterwill be. Therefore, the normalpressurecan varyfrom slightlysalt 0.433 psirzft(8.33 PPG)to highfyconcentrated salt 0.478 psy'ft(9.2 PPG)basedon salt concentration in water. is the pressure 2. SubnormalPressure: Thesubnormalpressure that is lessthan normal pressure problems. and it possiblycauseslostcirculation 3. AbnormalPressure:The abnormalpressureis the pressuregreaterthan the pressure columnof water.Generally, the abnormalpressurezonesare good reservoirwhich oil companies are lookingfor.Thiskindof pressure can createwell controlproblem.

Question;Whatis abnormal pressurerelatingto fluid pressurein the formation? Answer:Abnormal formation pressureis any formation pressurethat is Sreater than'normal'pressure. I I I I I I

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Lookingat the drawingbelow,it demonstrates the comparison of formationpressure whendrillingintoeachpressureregime.At the sameTrueVerticalDepth(TVD), subnormalpressure showsleastpressure in comparison to others.However, abnormal pressuregivesthe highestpressureat the samelevelof TVD.

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Someof the Gauses for abnormalpressures canbe categorized as follows: L. 2. 3. 4. 5. 6.

UnderCompaction ShaleFormation Faulting Artesian Effects GasCap ChargeSands Salt Dome

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1) UnderCompactionShaleFormation The rapid depositionof shale sedimentscausesa high compactionrates under the weightof materialsabove.The fluidsin shalecannotescapequicklyenoughwhilethe sedimentscompactionprocess being continued,the shale fluids will bear the overburden weightfrom above.At this point,pressurewithinshaleformationincreases pressurenot increasedue to the rate equalto that of a columnof due to overburden formationwater.UnderCompactionShaleFormationis causefor most of the abnormal pressurezones(Oiland gas fields)worldwide.

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The r apid bur ialof the shalecompac ti on during the shale sediment deposition createsentrapmentof the formationfluids. Thus,the trappedfluids will supportthe overburden weights which results in abnormalpressure withinformation.

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2) Faulting The up-thrustingfault zonescreate the "chargeup" formationof shallowdepthwhich containsfluid at pressuremuch greaterthan normalfor their depth or the fault itselfmay allowfluid seepageoverpart of its extent.

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Fromadjacentfigure,the left side of the fault zone is a normalpressurelocation.The rightsideof fault zone is an abnormal pressurelocation.This is becauseof the up-thrusting fault which movedthe formations upward when the shifted formation carriedits sameformationpressure.

3) ArtesianEffects An aquifer or water bearing permeable layer outcrops in the hills creates differential fluid pressure.The drive pressurefrom such a reservoir equalsthe waterheadat any point.

HYDROTIATIC ?R€38URE 7ROil

T he dr illingintothe aquiferout on the plainswher e its locationis at a lowerlevelthan the levelof water outcropup the hili,relatively creatinga shortcolumn of well fluid is availableto balancea longcolumnof formationwater.Hencean abnormallyhighpressure gradientwill be expectedwhendrilledinto the water zone.

Questron What hascreatedthe abnormalpressureby an artesianeffect? Answer:A reseruoirwater source locatedat a higher levelthan the rlgfloor.

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OrillineWell Control Manual

PTTCO Ltd.

Well GontrolManual Ghaptert

BasicTerms,Definitions,and Calculation

4) GasCap pressure from the deepestpart of the sealedreservoirs, In dippingor folded(anticline), reservoiris transmittedto the shallowersections.Pressureat deep end of the reseruoir if the gaswhichhasa lowerdensitythan oil maywell be normalfor that depth.However, and water presentinsidethe cap rock,the gas will transmitits pressureto the shallow thus abnormalpressure depthin lowergradientthan that of a normalgradientpressure, is alwaysseeninsidethe gascap reservoir.

Antlcllno

2125prl

GasGapsurounded by a normal prcssureFormation

To determinethe Formationpressurebelow the top of cap rock or anticline: From the fisure of SascaPabove; = Theformationsurriunding anticlinecontentswith salt waterof $radient o.465 psi/ft. (Normat$radient).Trapped$as Sradient= O-IOOpsi/ft' = 2,325 psi pressureat 5,000' = O.465x 5,OOO 7. Formation 2. Pressureof Gasinside anticlinecap,roek = 2,ooo x 0.7= 2oo psi 3. Formationpressureat the top of the anticlinebelowthe cap rock = 2,325 - 2OO= 2,725 Psi 4. The2,l2;psi is abnormalpressure,comparewith a normalpressureof 1'395 psi outside an anticlineat the same depth (we have 73O psi hi$her pressurethan normalin this examPle).

W e l l C o n t r o lM a n u a l Drilline

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Well GontrolManual Ghaptert

BasicTerms,Definitions,and Calculation

PAGE 17 of 38

5) ChargeSands well,somesimilareffect On drillingnearbyliveproduction Blowout" or "Underground of a downhole communication The high pressuregas in the deeper may haveoccurred. depth sand formation communicatesto the shallower sand formation,thus creatingthe abnormalpressureat shallowdepth.

)

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well haspoorcement Thiscan happenwhenthe producing jobs and or down hole equipmentleakagesor corrosion damages.

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6) Salt Dome In manyareas,a thick,pure layersof salt may be present.Saltformationis a creeping formationsto form salt domes. formationand often forcedupwardinto the overlaying formation,it exhibitsplasticflow ability,not allowingporefluids Salt is an impermeable the formationsbeneathand to migratethroughit. Becauseof this salt characteristics, besidethe salt layer are commonlyexhibitingthis abnormalpressuredue to its Piercedformationlayersare usuallysealedby the salt and lifted overburden. supporting up. leadingto migrationof oil and gas, later trappedin there and have pressurein formations. exoessof the surrounding

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. Norrnal Pressure-

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Salt is a CreepingFormation

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Well GontrolManual Chaptert

-

BasicTerms,Definitions,and Calculation

PAGE 18 of 33

1.10

4 /

FORMATION FRACTURE PRESSURE

-

The formationfracturepressureor the formationbreakdownpressureis the pressure requiredto rupturea formation,so that the wholemud can flow Into it. Thisformation breakdownpressureis usuallydeterminedfor formationsjust belowa casingshoe by meansof a Leak-offtest.The casingshoe depth is recognizedas the weak point in the well becauseit is not protectedby casing,and generally,the formationsat deeperdown belowshoehavemorecompactionthus they becomestrongerand hardercomparedto formationat shoedepth.

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1.11 GAS4UTMUD Most commonly,the oil companydrillsa well by keepinga small amountsof the over balancedpressure. Theobjectivefor thls is to maximizethe drillingratesand to saverig times.Whendrillingwith minimumoverbalance, small slugsof gas may enterthe well bore during connections. After the connection,pumps are turned back on, this gas becomesin gas-cut mud."Connection Gas/Gas-cut Mud"is the relatively smallamount of gas that entersa well when the mud pump is stoppedfor a connectionto be made. SinceBHPdecreases whenthe pumpis stopped,gas may enterthe well. (Note:"TripGas"is the gas that entersthe wellborewhen the mud pump is shut down and pipeis beingpulledfrom the wellbore.Thegas may enterbecauseof the reduction in bottom hole pressurewhen the pump is shut down,becauseof swabbing,or because of both).

-

l-

t4 ll-

Gas-cutis the situationwhen gas from formationsor a well bore mixedwith pressurein the well. mud,causinga reductionof mud hydrostatic Therewill be a smalldropin the bottomholepressure, but no kick as longas the hydrostatic headof mud still maintainedoverbalance or well is kept full o f mu d . Gas-cutmud will reducebottomholepressurethe mostwhenthe gas bubble is circulated up and nearsurfacedueto its tremendous expansion.

l1

,-

-

gas-cut.mud in a hole is to controlthe The precautionwhen encountered gas is in the holeat anyone drillingratesso that onlyoneslugof connection time.

t-

Theconnection time shouldbe minimized,itpossible.

-

Thesurfaceequipmentusedto removeElasin mud is vacuumdegasser. Gasshow:lt is gasthat appearsin drillingmud and it indicatesthe presence of gas zonesor solublegas in oil.

-

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BasicTerms,Definitions,and Calculation

stoppedbecauseECD(equivalentcirculatingdensity)decreases whenstop pumping. gasindicatesthat mud weightin holeis lessthanformationpressure. Connection 'Connection gaslevelwhen Gas"is distinctincreaseof gasabovea normalbackground bottomsup occursafter a connection.lf youseea small highgas peak in short periodof time andwhenyoucalculatebackyouwill seethat it comesfrom everyconnection, you cansuspectthat this is the Connection Gas. Theconnectiongasoccursbecausetotal pressure(hydrostaticpressure+ friction pressure) temporarily decreases duringmakingconnection. Basically, it meansthat you loseequivalent gascould circulating densitydue to pumpsoff. In addition,connection happendueto swabbingeffectwhenthe drillstringis workedoff bottompriorto making connection. Theconnectiongascan indicatethat pressurebetweenhydrostaticpressureexertedby drillingfluidandformationpressureis almostin balancecondition. Therefore, whenyou gas,youshouldconsiderweightingup mud in the systembefore seethe connection resumingdrillingoperationor trippingoperation.

Thedifferenceof Easshowand connectiongas: lf there is connectiongas,gas shownin a mud loggerscreenincreases gas and decreases sharplylikesmallElaspeak;however, gas.Lagstroke,lagtimesare showdemonstrates the smoothercurvethanconnection gasor gasshowcomesfrom.Especially, usedto findwherethe locationof connection gas presents, whenthe connection lagtime of gas peakwill be relativeto the time when pumpsareoff. Tripgas:lt is gasenteringto well borewhentrippingout of hole.Thereareseveral factorsas balled-up bit,fast pullingout rate,biggerdiameterBHA,etc cancreateswab pressure effectthat can reducehydrostatic whiletrippingout of hole.lf too much pressure reductionin hydrostatic is present, formationgascan influxintothe well bore, called"Tripgas".

)

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19 of 33

gas:lt is a relatively Connection smallamountof gasthat enterswellwhenmud pumpis

t t

PAGE

Question.'What may causeTrip Gas? Answer: A reductionin BHP.

PIT {;

Well ControlManual Chaptert

and Calculation BasicTerms,Definitions,

PAGE

20 of 33

Example: droP the pressure Calculate in BHPwhilecirculating gascut mudin thiswell:

11ppg = 4OOpsi +.

12ppg 1500 1 2 . 5p p g

= 499 psi +

7000 AnnulussflP = 447tt psi

HSP Surfaceto 700 feet

:700 x llx.052

'- 400 pti

HSP frour 700 - 1500ft

:800x12x0.052

-* de9 pri

ft HSPfrom 1500- 7CI00

:5500x12.5x0.052

=. J5r 5 pr i

'.ilotnl arntnltts F{5F

= {{)ll * {99 + 3575

: 44?4psi

IISP of original mud

:7000x12.5x0.052

- .[550psi

Reductionin BHP

= 4550- 447,1

= 76 psi

gascut will causea smalldropin BHP) (Mudwhichis sufficiently 1.12 TRIPMARGIN in the well,causin$a dec r eas e D u r i n gp u l l i n go u t o f h o l e ,th er eis a chanceof swabbing in the bottom hole pressureand the well may flow. An extra mud weightshouldbe mudw ei ght( i n An incr eased oper ations. a d d e dto p e rmi ta sa fetri p p ingand connection that a trip marginand a slu$ are ppg)is called.TripMargin".Thereis a misconception betweenthe two: thereare importantdifferences the same.However, o

the BHPpr iorto the tr ip as longas the slugi s s ti l l i n A sl u gw i l l n o t i n c r ease th e d ri l lstri n g .

o

Trip marginwill certainlyincreasethe bottom hole pressuredue to mud weight increaseto compensatefor the loss of mud hydrostaticpressure causedbYswabbing.

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Well ControlManual Ghaptert

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PAGE 2Lot 33

A I I a

To determine a new mud weight to be circulated throuSh the well prior to pulling out of hole with regard to addingthe safetyTrip MarSin; Given: Well depth to,ooo ft. $/D) MW !O.O pp€, An extra pressure required at the bottom of the well = lOO psi

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a

7. Hydrostaticpressureat bottom holedue to MW = O.O52x 7Ox IO,OOO= 5,2OOpsi 2. Total BHPincludingan extrapressure = 5,2OO+ 70O = 530O psi 3. New MW to be fully circulatedprior to POOH 5,300 = 10.Zppg 0 . 0 5 2x 1 0 , 0 0 0

t t t t t t

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L13 SHALLOW GAS In the top hole section,drillingrate is normallyvery fast, hole sizesare very large, porosityis very high.The carrying-up cuttingscapacityand annularvelocityis relatively low.Thisleadsto largeaccumulated cuttingsin annulus.Theformationstrengthis also commonlylow,moreso in offshoredrillingwellssincethe partof overburden consistsof seawaterratherthan a wholeformation.

n 2 2 t ?

Variousproblemsmay be encountered while drillinga top holesection: o a

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Theformationbeingweakis vulnerable to bulkmud losses. Fastdrlllingin soft formationat top holesectiongenerateslargevolumeof cuttingsthat tendto accumulatein the borehole. Shallow gas kick occurs quickly and shallow reservoircan have high permeability, time for actionis verylimited. Formationis weakand riskof craterwhenshallowgaskick. lt can leadto blowoutcausingseriousdamageto personnel, rig and eq u i p me n t.

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PreplanninEto preventthe shallowhazards:

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'sparker surveys"if availablecan be useful i n Shallowseismic informationfrom these "bri$htspots"may be Occasionally detectingsmall shallowgas accumulations. pressure and low volume. they low are gas at high pressure,thoughmorecommonly Normalpracticeto avoidshallowgas kick:

/la ll-

/

o Drillwithpilothole. . Pumpingout whiletripping(POOH). o Controldrillingrates.

-

Principlesof handlingshallowgas:

F

Activatethe divertersystemif it is in place. Increasethe pump speedwith maximumrate to keep as much fluid in the well as possibleand let gasthroughthe diverter. lf mud finished,pumpseawateron offshoreri$s. Do not closethe BOP,onlydiverterto be usedin orderto avoidanyformation

a o

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fractureand losses.

ShallowGas

r F ?' t-

ShallowGasGontrolProcedures:

r r -

WhileDrilling: lf flow checkconfirmedthat the wellis flowing:

-

r r

.

on winddirection). Opendiverterlinevalves(depending

o

Closediverterpacker.

o

out the kickat maximumpossiblepumpratewith availabledrilling Circulate

F F

fluid.lf mudfinished,pumpseawateron offshorerigs.

-

from the ri$. Removenonessentialpersonnel

-

o

s F F F

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23 of 3if

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PAGE

WhileTrippinE: o

Spacetooljointaboverotarytableandset the pipeon slip.

a

Installthe full openingsafetyvalve(FOSV), thencloseit. Opendiverterlinevalvesto the downwinddirection.

a

o

Closethe diverterpacker.

a, ,1,

a

Makeup the kellyor circulating head.

a

OpenFOSV.

a

a

Circulate out the kick at the maximumpumpratewith available drillingfluid.

1'

Removenonessentialpersonnelfrom the rig.

,

,4,

e e

LL4 . BASICPRESSURE AND PUMPSTROKE CALCULATION

1'

1)

e t

PressureGradientand MudWeightrelationship:

e t

s e

From the HydrostaticPressure Formula: Pressure

= O.O52x ppgxfr.WD)

t ;

s s t

rearranSingformula; i)

psi/ft

=

O.O52x ppg

ii)

ft. 6/D)

=

psi + (O.OS2x ppE)

ppg

=

(psi/ft) + o.o52

,

t

iii)

]

q

t

ToconvertppStoGradient-> multiptyby O.OS2 ToconvertGradientto pp€-> dividedby O.OS2

Example: Find the Pressure,column Height and Mud Wei{ht from given fluid gradients: aabulate MW (pp€) O.33psi/tt O.46psi/ft

= 6.35 ppg = 8.85 pp(,

B. Calculate Gradient(psi/ft). = 3.0 ppg 0.756 psi/ft :8.94 pp! 0.465 psi/ft C. CalculateColumnheight(ft) O.45psi/ft with2,5OOpsi = 5,556ft. O.35psi/ft with3,OOO psi = 8,57I ft.

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(Pump)pressure effectsdueto pumpspeedandMWchange: Clrculating

P2: PLx

Where : PL P2 SPML SPM2

MW2 *r,

W her e: = Old circulationPressure = New circulation Pressure = OIdpump Stroke = Newpump Stroke

PI P2 MW! MW2

-

-

= OId circulationPressure = New circulationPressure = OIdmud Wei$ht = New mud Wei{ht

11

-

*amples:

-

Example7: A pump pressureof !,0OOPsi was recordedat pump speedof 4OSPM'What is the Pumppressureat a sPeedof 3O SPM? Newpump Pressure= P2 PZ = 1000x

Example2: A pump pressureof 7,OOO Psi was recordedwith mud densityof 77 pp$at a speedof 4OSPM.Whatis the PumP pressureat 40 SPMif mud densitYis increasedto 73 pP$?

-

Newpump Pressure= P2

-

P2:1000x

(ii)

- t,l82psi

= 562.5 psi

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PAGE 25of 3(|

Example At 35 spm,with 1t ppg mud,the pump pressureis 900 psi.calculatenew pump pressure when pump rate was changed to 25 spmwith L2 ppgmud ?

,

t t t t , ,

9. I.IEWPUMPPRESSURE(PSi)WITH NEW PUMP RATEAPPTOX|MAIC =

otd PumpPressure(psi)t (

)'

t25tz - 900 x (-l - 459psi NewPumppreSSUre

, ,

10.NEWPUMPPRESSURE (psi)wlrH NEWMUDDENS|TY approximate=

,

t t t ,

t ,

}Id PumpPressure(psi) x

New Mud Density(ppg) Old Mud Densi.ty(ppg)

NewPumpPressure- 459

"(i?)

- 5 0 0p s l

Answer: NewPumpPressure= 500 psi

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P O R O S I W: e a tth e volum eof the por espacebear sto thetotalbulk T h ep e rce n ta gth ' clume (Thepercentage of spacebetweenthe grainsof rock).Theporespace l e t e r m i n e sth e a mo u n to f sp a cea vailable for stor ageof fluids) .

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Chapter1:BasicTerms,Definitions,andCalculation 26 of 33

)

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- A key Theabilityof a rockto transmitfluidthrou$hthe porespaces PERMEABILITy: fluid'Thereis no necessary influencein the rateof flow,movementanddraina$eof the A rockmay be hi$hlyporousandyet relationbetweenporosityand permeability. betweenpores.A highlyporoussandis if thereis no communication impermeable u s u a l l yh i g h l YP e rme a b l e .

Fluids

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-

of Pressure, to BasicDefinitions related andstatements 1. Belowarewordings to the blank(a h): Matchthe nuriber(1 - 7) correctly of fluidbyvirtueof itsdensity Oya stiticcolumn exerted 1. pressure overa givenunitdepth of fluid whichmeasured 2. Pressure 3. Forceexerted Perunitarea at the bottomof the hole pressure arebeingexerted 4. Sumof all 5. 0.465Psi/ft. .., , e ---r. the poreof the Formation exertedby fluidwhichtrapped"in 6. Pressure Shale's 7. UnderComPacted

l-

/

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a) Pressure

-

b) BottomHolePressure Pressure c) Formation

-

Gradient d) Pressure Gradient e) NormalPressure f)Causeofabnorma|FormationPressurewor|dwide

-

a F aa

Pressure g) Hydrostatic CopyrightReserved

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2.

27 sl33

Determine the Bottomholepressure, MudweightandPressure from Gradient givendatabelow: a) TVD= 10,000'

MW= 9.6ppg

BHp=

b) TVD= 14,000'

MW= 12.0ppg

BHp=

c) WD = 8,500'

MW= 9.5 ppg

BHp=

d) BHP= 4,850psi

at 7,000'WD

MW=

ppg

e) BHP= 6,840psi

at 12,000'WD

MW=

ppg

0 BHP= 7,230psi

at 12,000'TVD

MW=

ppg

g) BHP- 4,430psi

at 8,000'WD

Gradient=

psi/ft

MW=

ppg

h) Gradient= 0.455psi/ft.

3.

PA(3E

,

psi psi

.

psi

Calculate the BottomHolePressure whenwellhasmixtureof differentmud weightsasfollows: TVD = 6,000ft. Fromsurface to 500ft, MW = 10.0ppg From500 1,300ft, MW = 11.0ppg From1,300- Bottomhole,MW = 11.5ppg Answer:BottomHolePressure=

4.

Calculate theCirculating BHPandEquivalent circulating density(ECD)from givenwelldata: TVD = 10,000 MW = 10.5ppg ft. Annularpressure loss= 150psi = Answer:Dynamic BottomHolePressure Equivalent circulating Density =

tt

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/

pressure (pumppressure) dueto changein pump the newcirculating Calculate strokeandmudweight: (psi) Pressure NewPressure NewMud OldMud

/ /I

a)

9.7 ppg 10.0ppg

1,850psi

b)

11.5ppg I2.2 ppg

2,500psi

c)

11.0ppg 12.6ppg

300psi

OldStroke NewStroke

Pressure

d)

75 spm

40 spm

2,450psi

e)

30 spm

60 spm

400psi

0

20spm

B0 spm

180psi

I aJ

I

(psi) NewPressure

-

/

/ F

6.

pressure for the Mudweightrequiredto balanceFormation Determine pressure andTVDdepth: followingbottomhole

a) 4,850psiat 7,000'

Answer:

ppg

b) 6,840psiat L2,000'

Answer:

PPg

c) 9,900psiat 15,000'

Answer: .

ppg

d) 3,560psiat 7,000'

Answer:

ppg

e) 4,430psiat 8,000'

Answer:

ppg

la

F F

/ ;

C F F

0 7,230psiat 10,000' 7.

Answer:

PPg

gradient pressure is basedon a fluidweightof: formation Normal

l-

a) 6.93ppg b) 7.18ppg c) 8.34ppg

/

@ a.s+pps

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Chaptert BasicTerms, Definitions, andCalculation

)

PAGE 29 of 33

Whichof the followingsituations is likelyto inducethe greatestswabbing duringtripping?

) )

a) Whenpullingfirst few standsoff bottom b) Whendrillcollarsare passing intocasing c) Whendrillcollarsare liftedout of hole

) ) ) )

9.

) ,

Whichof the followingsituations will probablyresultin Swabbing? (Select3 answers) a) The mudpumpis runningwhilepullingout of holewiththe drill string b) The mudviscosityis too high c) Pulling the drillstringthroughtightspotswithoutpumping d) Pulling out the drillstringtoo fast e) Pulling the drillstringthroughtightspotswhilepumping f) Pulling on the drillstringslowly

) ) )

I t 10.

pressure In the Oilfieldthe hydrostatic is a functionof: a) b) c) d)

11.

Whendoesexcessive Surgingoccur?(Select2 answers) a) b) c) d) e) f)

12.

Drillstringlength Pumpoutputper minute Theverticaldepth porosity Formation

Pulling out the pipetoo fast Largeannularclearance Impropercirculating density Running in too fast Lowmudviscosity Tighthole

The equivalent circulating density(ECD)is considered the effectivemud pressure weightwhilecirculating. Which lossin the circulating systemis added to staticmudweightto find it?

pressure a) Surface loss b) Drillpipepressure loss pressure c) Drillcollar loss d) Bit nozzlepressure loss pressure ei) Annular loss

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-

30 of 3il

-

1 3 . Whatis theeffecton bottomholepressure whencirculating compared to static situation?

/

a) Bottomholepressure is greater b) Bottomholepressure is lesser c) Nochange in bottomholepressure -a

14.

Whichof thefollowing pressure? alternatives doesnotcauseabnormal

I

a) Anexcessive overburden weight b) Upward Faulting c) Anincrease in shaledensity d) A gascapeffect e) A artesian effect 15.

WellA is drilled to 9,000'WDwith9.5ppgmud.WellB is drilled to 9,000'MD (8,500'T/D)withthesameMW.Whatis thedifference pressure in hydrostatic the at bottomof thetwowells? a) b) c) d)

l-

lta

180psi 225psi 247 psi 325psi

lll-

,-

16.

To adda 200 psitrip marginto yoursystemcontaining MW 13.5ppg at a depthof 2,900'.Whatwouldbe the requiredmudweight? a) b) c) d)

-

14.8ppg 15.0ppg 13.2ppg 12.5ppg

-

17,

The 3,500'TVD wellcontains 9.5 ppgMudweight.Whatis the hydrostatic pressure at the 2,900'WDcasingshoe?

-

a) b) c) d)

1,500psi 1,650psi 1,433psi 1,350psi

Fl

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Calculation vr'Yrr Ghaptert BaslcTerms,Definltlom,and Il l "ru

PAGE srca3

18. Whatshouldbethevalueof Gasinfluxgradient? a) b) c) d)

./

19.

Lessthan0.156psi/ft Equalto 0.465psi/ft Morethan0.465psi/ft Equalto 0.433psi/ft

to the minimum mudweightrequired Fromthedrawingbelow,calculate pressure whendrill.at2,200ft: theformation balance

1341psi

Mudweight(PPg)=

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20.

PAGE 32 of 33

Fromthedrawing below,theGaswastrappedunderCaprock(Anticline mud the pressure at topof thegascapandthe minimum Structure). Calculate weightrequired to drillintothetopof thegascap; psi/ft. Pressure at OilandGascontact= 0.447' Gradient Given:Assume = 0.104psi/ft. GasGradient

€ ( ( (

C -

e e F F F F -

3000 ft

e-

F F F -

Pressure at top of gascap =

,: .

psi

-

required Mudweight= Minimum

ppg

-

F F F F F F F F F F F -

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Well GontrolManual Definitions, andCalculation Chapterft BasicTerms,

D ,

Erercbe- 1.Answerkey l

-

t t I f

b b

a b c d e t g

z

b

a b c d

e f 6 o

h

b b

b b

b b b b b b b b b b b b b b b b b

3 4 6 2 5 7 7 4992 8736 4199 13.3 11.0 LL.6 O.5s3 8.8

psi psi psi ppg ppg ppg psy'ft ppg

BottomHolePressure= 3528.20 Psi 4.

DynamicBottomHolePressure= 5610 psi Density= 10.8 PPB Equivalent Circulating

5.

a b c d e

t

L9O7 psi 2652 psi psi 344 697 _--psi 1600 psi 2880 psi

6.

a b c d e f

13.4 L1L2.7 9.8 to.7 13.9

7. 8. 9. 10. Il. ll. li. I -1. 15. 16. 17. 18. 19.

o

20

Pressureat top ofgas cap : 1315psi Minimum requiredMud weight:9.2 ppg

ppg ppg ppg ppg ppg ppg

A

b.c.d d.f d

2

a

Mud weight: 11.72 ppe

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Well GontrolManual

PIT

Chapter2: WellVolumeCalculation VOLUMEORCAPACITY CALCULATION: on the drillingrigs,therearetwo commonshapesof objectwhichhavebeen deployedeitheras facilitatedequipments or as drillingequipments. Square The squareshapedobject is similar to the m u dt a nk a n dth e tri pta n k. Clinder The cylindershapedobjectis similar to the w e l l . t he ca si n g th , e d ri l l p i p e and the dr ill collars.

It

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t |l -a

T h ev o l u meo f th esq u a resh a p ecanbe determinedby simplymultiplyits lengthby its w i d t ha n d b y i ts h e i g h t. = L x W x H

T h ev o l u meo f th e cyl i n d esh r a p ecanbe d e t e r m i n ebdy u si n gfo rmu l a :

rExRzxH

or

TTXD2XH

Where, 1 (pi)= 3.1,4L6(theconstant,is a ratio betweenthe diameterandthe circumference) R = Radiusof circle(distance from the centre to the outeredge). D = Diameterof the circle(distance through the centrefrom edgeto edge). T h ec o m mo nu n i tso f vo l u mea recubicfeet, cubicmeters,USgallonsand barrels.

t Reserved

D r i l l i n eW e l l C o n t r o M l anual

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Well ControlManual

lPAGE

Chapter2: WellVolumeCalculation

lf

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2.2

l-

STRINGCAPACITY ANDMETALDISPI.ACEMENT CALGUHTION:

lr

lr

To findvolumeor capacityof a cylindershapeor hole; Capaci$= Baseareax Lenglth or Depth Theterms of baseareaare expressed in the followingdrawings:

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-

L

Annuhrrpocobctncrn rffng and crring

Annuhrrplcr brlt*n drilldringendholr

0rill *ing Crproty Dtill lbing llchl Ditphcamrnt

Dilfihahcshr

Ihf @hryordc

StringCapacity: StringCapacityis determinedby: lTXD2XH

a

Dilllstdng Capacily

4

bbl/ft =

D2

m

Inputthe conversion numbers: = inch D 1sq. feet = L44sq. inch l- cubicfeet= 0.1781bb| In 1ft. columnheight,the capacity will be: bbl/ft

C o p y r i g hRt e s e r v e d I

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=

3.1416xDzxO.I7BL 4xL44

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Chapter2: WellVolumeCalculation

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MetalCapacity:

t I

bbl/ft =

t t t t

StringMetalDisplacement can be determinedby:

oDz - IDz ro29.4 Inputthe conversion numbers: ODandlD of dr illstr ing= inch = L44 sq. inch 1 sq.feet = 0.1781bb| l cubicfeet In 1ft. columnheight,the capacitywill be;

2 ,

t t t t

hbl I ft

1'

t

e , ,

LO29.4

Alote; The metal displacement calculated by this formula is valid only for drill strinSs not including upset or tool joinb.

;

t t

oDz - IDz

Example:

Example:

hlculate internal capacity(bbl/ft) of Calculatethe metal displacement(bbl/ft) ot 5' Dritl Pipe.#79.5\bs/ft, 6-3/4" Drill Collar,lD = 2-7,/2" = lD 4.276' 4.2762 6 . 7 5 2- 2 . 5 2 bbllft= = 0.0382 LOZ,-.4=0.0178 L029.4

, , ,

23

STRINGCAPACITY IN THEWELL

,

t t

In th e o i l wellther ear e inter nalcapacity of dr illstr ingas follows:

,

. . .

, )

t

DrillPipeCapacity x Lengthof Drillpipe HWDPCapacity x Lengthof HWDp DrillCollarCapacity x DCLength

Volumeof Drill pipe(bbls)= DP cap.(bbl/ft)x DP.LenSth (ft)

, )

Volumeof HWDP(bbls1=HWDPcap.(bbl/ft)x HWDp tengtn6t)

t t t

Volumeof DC

= DC cap. (bbl/ft) x DC tenstn(ft)

)

t t )

CopyrightReserved

D r i l l i n gW e l lC o n t r o M l anual

I

Well ControlManual PAGE

Ghapter2: WellVolumeCalculation

4ot7

-

CALCUI.ATION 2.4 ANNUI.ARCAPACITY -

by : Annularcapacitycanbe determined

StringMetalDisplacemenl

lD is the insidediameterof the outerstring or holesize. OD is the outsidediameterof the insidestring numbers: Inputthe conversion = inch str ing dr ill and lD of OD = L44 sq. inch 1sq. feet l cubicfeet = 0.1781bbl

t

In 1ft. columnheight,the capacitywill be; bbl/ft =

IDZ _ ODz

bbl/ft

to29.4

=

ODz_ IDz LO29.4

Fs
Example:

Calculateannular capacityof 5" drill pipe, #79.5\bs/ft. inside9-5/8' Casin!,,#4O.O Ibs/ft,N-80,(lD= 8.687");

Calpul?teannular capacityof 6-t/2" drill collar,# 99lbs/ft inside8-7/2" hole;

bbl/ft -

B .6 B t2 - 5 2

to29.4

: O.O4892L

bbl/ ft -

9 . 5 0 2- 6 . 5 0 2

to29.4

: O.O29t / /

l anual D r i l l i n gW e l lC o n t r o M

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Well GontrolManual PAGE

Ghapter2: WellVolumeCalculation

5of7

q a I a I a fl t

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IN THEWELL 2.5 ANNUALRCAPACITY Annularcapacitiesin the wellarevaried on the sectionof casing,drillpipeand depending drillcollars.In general,the surfaceBOPstack will consistof threesectionsof the annular capacities; . .

.l

a rl

.

Casingand drill pipe

Annularcapacityof drillpipein casing. o f d ri l lp i p ei n open A n n u l aca r p a ci ty h o l e. Annularcapacityof drillcollarsin open h o l e.

holeand drill pipe

a .l

rl rl al

a .l

a a rl

a

Annularvolume betweendrill pipein casin$ = DP/6G. cap. (bbl/ft) x Casin$length(ft). holeand drill Collar

Annularvolume betweendrill pipe/ openhole = DP/ OH.cap. (bbl/ft) x DP/OH Len$th(ft)Annularvolume betweendrill collar in openhole = DC/ OP.cap.(bbl/ft) x DC Len€th(ft).

Forthe subseaBOPstack,thereis an extraannularcapacityof drillpipein for fillingthe kill mud marineriser.Thiscapacityshouldbe considered *right afterkillinEwell.

a it

a

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a rl rl

CALCULATION PUMPSTROKE the totalstrokescan be determinedby relationship Afterhavingthe volumein barrels, as follows:

2.6

Pump Strokes Volume(bbls) Pump output (bbl / str o ke)

b
t7s

:-:L.6O6strokes 0.1090

rl

? 2 2 2 t a

W e l lC o n t r o M l anual Drilline

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PAGE 6of7

2.7

TIMETO PUMPCALCULATION

Strokes Pump r ate (Str oke / minute)

-

-

Afterobtainingthe pumpstrokes,the pumpingtime in minutescan be determinedby relationship as follows:

Times to pump

-

Example: Total strokestopump in drill string= 1606 strokes Pump rate = 3O strohes/minute. Total times to pump in drill strin{, L606 =

-

-

. SURFACE VOLUME CALCULATION GENERAL BOP

-

Well Data: Hofesize 8-1,/2" Depth Hole 11,536ft.(M TVD) 9-5/8" Casing 9,875 ft. (M TVD) 5' HWDP 600 ft. G1,/4"DrillCollar 880 ft. DrillStringCapacity; 5" DriffpipeCapacity O.OL741,bbl/tt 5' HWDPCapacity 0.00874bbl/tt G1,/4"DCCapacity O.OO492bbl/tt

-

AnnulusCapacity; DCIOpenHole HWDP&DPlOpen Hole DPlCasing

-

o.0322Lbbt/tt o.o447Obbt/tt 0.04891bb1/ft

Note: Drill pipe len{th = Well depth- DC- HWDP

-

HWDP&DP/Open Hole length= Welldepth - DC - CasingShoedepth

l,J

Well ControlManual Chapter2: WellVolumeCalculation

2.8

PAGE

7 otT

- SURFACE GENERAL VOLUME CALCULATION BOP(Continued) Drill StringVolumeCalculations(Drill pipe length= Well depth- DC- HWDP)

DilSthgtfrmnir

DrlSuh6V*rtF&bb) Len$h(fl)x Capaeitv ibbfft) Vdumen OdNpin (tib)

@xl

= ont74l

Vdune in l-ftfDP(trbb)

F]xFoosal = l-;l

VotureintE (Hs)

ExFq=|J3 l Tffil voftrnem m (tbb)

=

AnnulusVolumeCalculations

tMPt{Fx0mll*S{

=l-lqsll ,ruxl oo4fil lf xOpcl&& 6U{

IqrFq

=lzffi4l

Isdorruohyksu$ =[ffi2fl TotdArrx-fusVdnre(bb) =

(HWDP&DP/Open Hole length= Welldepth - DC - CasingShoedepth)

CopyrightReserved

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Well ControlManual

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Chapter3: Slow Pump Rate,Leak Off Test and MAASP

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3.1

PAGE Lol37

SLOWCTRCULATTON PUMPRATE

Wellcontroloperations are performedat reducedpumpspeed.Kicksmust be circulated pressure. out at SlowCirculation Rate(SCR)with kill ratecirculating Theobjectives are:

I

II

rl

.

pressure plusthe SIDPPis convenient To ensurethe slowcirculation for pump and doesnot exceedthe surfacelinerating(MudGasSeparatorlimits). To allow mud returnsto be weightedup and re-circulated within the mud mixingcapacity. To preventthe dangerof fracturingthe formationat the casingshoe. To allowlongerreactiontime for chokeadjustment. To allowsufficienttime for disposalof kick at surface,especially the critical conditionwhen gas influx at surface reachesthe maximum pressure especially with mud seallimitationof MudGasSeparator(MGS). To reduceannularpressureloss for a better control of the bottom hole pressure. To reducechokelinefrictionloss.Thisgreatlyaffectsthe killingoperations on the subseaBOPstack,in the deepseawateroperations.

.

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Gooddrillingpracticesrequirethe Slow Pump Rate Pressure(SCRP)be checkedand necorded regularlyby the driller.TheSCRPmust be recorded: e With bit nearbottom . gaugeon the chokepanel Onthe drillpipepressure r At the beginning of eachshiftor tour. . Afterchangein drillingmud density. o Afterchangesto the bit nozzlesizeor BHAconfiguration. o Afterdrillinga longsectionof hole(i.e.500') in a shift. o Aftermud pumprepairsor equipmentchanges. o At changeswhichcausea differentcirculation, or fast drillingsectionwhere d ri l l i n gp a ra me te rs ma y be changed. SCRPressureshouldbe recordedfrom the gaugethat is to be used for well killing gauggon tlie drillerrsremotechokepanel. operationwhichis on the drillpipepressure

a

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J

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-

I

-

I

-

Example

WaitandweightMethod.TVDof well:5538 ft psi at 30 SPM,MW = 12.6 ppg SCRpressure:24O SIDPP: 610 psi,SICP:7LO psi,MW in the well : 10.43 ppg Calculate the FCPat 30 SPM?

14.KIIL MUDDENsITY(ppg) = =-3T3-(pt=')' ^ * orisinal Mud.Density(pps) TVDut) x 0.052 KILL MUDDENSITY=

610 + 1 0 . 4 3: 1 2 . 5 4 p p g 5 5 8 3x 0 . 0 5 2

16. FINALCIRCULATING PRESSURE(psi)

I I a I

-

I I

? ll

KtlI Mud Density (ppg) x Ktll Rate Ctrculating Pressure(psi.) }rigtnal Mud Denstty(ppq) 1.2.54 x 240 = 289psi FCPat 30 SPM : 10.43

-

Well ControlManual

IT

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Chapter3: Slow Pump Rate,Leak Off Test and MAASP

PAGE

2ot37

-

(LOT) LEAK-OFFTEST

3.2

-

-

Leak Off Test is conductedto determinethe pressureat which a formationbeginsto leak. In anotherword, the leak off test is to determinethe potentialof exposed untilthe next formationcan withstand,an exertedpressurein excessof mud hydrostatic casingsettingdepth.lt is usuallyconductedafterdrillingout the shoeand 10 to 15 ft. of rat hole.Forlongopenholesectiondrillingwhenevera weakerformationhasapparently beendrilled.Someoil companiespreferanothertest,namelya FormationIntegrityTest (FlT).lt is madeto determinewhetherthe formationcansupportmud of higherdensity. test shoeandformationuntilformationbreaksdown. LeakOffTest(LOT)- youpressure

-

Leakoff Testis conductedin orderto find the fracturepressure(fracturegradient)of the LOT,youwillpum pdr illingfluidto untilyou f o r m a t i o na n dsh o e Wh . e nco n d ucting formationis fractured, that Once the first pressure seethe fracturetrendof formation. We usethe leakoff pressure deviatedfrom a trendis typicallycalledLeakOff Pressure. mudweightthatcanbe appliedto a welldur i ng t o c a l c u l a te th e ma xi mu me q u i valent drillingoperations. FormationlntegritvTest(FlT)-youteststrengthof shoeandformationto designed pressure (or its mud wei$htor gradientequivalent).

-

-

FormationIntegrityTestis typicallyusedfor testingstrengthof formationand shoeby (BHP)to designedpressure. Whenyoudo the FITtest, increasing BottomHolePressure

-

youwill increasesurfacepressure untilit reachesthe requiredpressure only.Thereis no intentionto breakthe formationwith FlT.Youwill do FITto ensurethat youwill be able

-

-

-

to drillto sectiontargetdepthandwill be ableto controlthe well in caseof wellcontrol blowout. situationwithoutunderground

Thenecessityof the LeakOffTestis: o . o

To ensurethe strengthof cementbondaroundcasingshoe. (MAASP). To determinea MaximumAllowableAnnularSurfacePressure fracturing the formation at casingshoe. To controlkickswithout

Equipmentsand Materialsrequiredfor obtainingthe correctedLeak-OffTest: . . o o . o o

pressure). Cementpumpunit(lowvolume-high with easyto read pressurescaleor Calibratedpressuregauges.(Preferably ca l i b ra ti o n ). gaugeor tank. Calibrated volumemeasuring L i n eu p o f p i p i n g& va lvefr om pumpto well. BOP. and containgoodhomogeneous mud. Wellcontentscirculated Correctedcasin$shoeTVD.

r i e h tR e s e r v e d I

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PAGE 3 of37

teak Off Test Procedures: Drillingout the casingshoeand 10 to 15 feet of newformation. P u l lth e b i t i n si d eca si n g . Conditioned mud beforedoingLOT. Closethe preventer on drillpipeand openannulusbetweencasingstring. Pumpintowellwithselectedpumpin increments of 0.25 to 0.50 barrel, pressure in controlled (or stageswaitingfor to stabilize graduallypumpsmall amountof drillingfluid intowellwith constantpumpstrokeand pumpstrokesare 5 to 1Ostrokesperminute.Recordtotal recommended pumpstrokes,drillpipepressure and casingpressure. Drillpipepressureand c asi n gp re ssu re w i l l i n cre ase continually whilepumpingdr illingfluidin hole. Whenplottinga graphbetweenstrokespumpedand pressure, if formationis not broken,a graphwill demonstrate a straightlinerelationship. When pressure exceedsformationstrength,formationwill be brokenand let drilling fluidpermeateintoformation,thereforea trendof drillpipepressureand casingpressure will deviatefrom the straightlinetrend.Thefirstcasing pressure that deviatesfrom the straightllnetrendis calledas leakoff test pressure). plot stabilizedpressureversustotal volumepumpedfor Simultaneously eachincrement. Continuepumpinguntil the plotted curve beginsto flatten or when first deviationawayfrom the straightline.Stoppumping. Releasepressureand measurethe volumeof mud lostto the well. Recordedpressuresusedto calculateFormationstreng[h.

a a a a a

FinalPumping Pressure After I_ EachVotumeIncrement Alter ,r FinatSiaticPressure EachVolumeIncrement

uJ ar l

a

E-'- Leak-offPoinr

TU I

CUMULANVE VOLUME

CopyrightReserved I

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WellGontrolManual Chapter3: Slow Pump Rate, Leak Off Test and MAASP t

t

t

t

PAGE

FJ

4o137

l

ryprcarHressurel.rot ror Formation Breakdown and Fracture Prooaoalion

Formation Breakdown Pressure

I 4)

r u E 6

o U E A F a

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plotlng prcw6 FIOTE:Cofficm and pumpGd Yolum alicr p rosu rl ng u p to Ano psl

-

-

Maxtmum o'"*

-

LOTpressure(pst) :"*T::;::^,1,*J, !,'* r^ . 0.052 x ShoerVD(f t)

Fracture pressureat shoe(psi) Fracture pressuregradient at shoe(pst/ft) = Casing

-

-

Example:

-

Leakoff test pressure= 1600 psi

-

CasingshoeTVD= 4000 ft

-

Currentmud weightin wellbore= 9.2 ppg M a x i m um A IIo w a b IeMu d Weight ( ppg) = 9.2 I

-

1600 = L6.g ppg 0 . 0 5 2x 4 0 0 0

,fl

1

C o p v r i e hRt e s e r v e d I

Orilline W e l lC o n t r oM l anual

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Chapter3: Slow Pump Rate, Leak Off Test and MAASP

PAGE 5 of37

3.3

M$OMUMALLOWABLE ANNULARSURFACE PRESSURE (MAASP) MAASPis the highestsurfacepressurethat can be allowedat the top of casingand, if exceeded, is likelyto causemud lossesto the open holeformationat the casingshoe depth.Thereare threefactorsdecidingthe initialMAASP. r Themaximumpressure that the surfaceequipmentcan handle. . Themaxlmumpressure the casingcan handle. ' The maximumpressurewhichthe formation,at the casingshoe,(or a weak pointin the well)canwithstand. blAAsP= = NIAASP

Shoestrength- Hydrostatic pressureheadof fluid abovethe casingshoe Maximumshoepressure- ( O.OS2x ppgx TVDshoe)

.

v arimumMw(pps) = m".##

i a

InitialMMSP (MAASP afterwellshutin) = (Max.MW -CurrentMW ) x 0.052x TVDshoe.

I

= ( Max.MW - KillMW ) x 0.052x TVDshoe As the maximumshoepressure remainsconstantthe hydrostatic pressureinsidecasing is the determining factorfor MAASpat anygiventime;

I

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:?:;:;:; i

"

IAASPafter kill well

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) t

) Ia

= TestMW + LeakOff TestPressure 10.052x ShoeTVDI

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Question; Whenis MAASPchanged? Answer: After mud weight changed.

D r i l l i n eW e l lC o n t r o M l anual

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WellGontrolManual

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Chapter3: Slow Pump Rate, Leak Off Test and MAASP

PAGE

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rJ -

Example:

= 3,500 ft. MD/TVD SurfaceCasingShoe = 1,350 ft. MD/TVD Leakoff test Pressure = pp8 8.5 TestMW Drillingcontinueuntildepth5,000ft MD/TVDwith 9.5 ppgMud. at that depth? Whatis the maximumallowablesurfacecasingpressure

-

(ppg)= ALLOWABLE MUDDENSITY 11.MAXIMUM

tF

-

LOTMud Densi.ty(ppg)

-

1350 + 8.5 = 7.4L+ 8.5 ( 3 5 0 0x 0 . 0 5 2 )

l-

= \s.gtppg -

(psi)= l2.MAASP

l-

fMaximumAllowableMud Density(ppS)- Current Mud Density(pp7)l x 0.052x ShoefVD(f t)

-

= [15.91- 9.5]x 0.052x 3500: ' l- L66pst -

3.4

-

PRESSURE INTHEWELL FRACTURE

The fracturepressureof a formationis the total pressureat which the formation materialwill break down, thus allowingfluid to escapefrom the wellboreinto the formation.Duringthe well planningstage,the casingshoedepthplacement surrounding whiledrillinga well, will be advised,with relationto the formationstrength.Practically, the formationstrengthis recordedby meansof a LeakOffTest,meaningthat the weak p o i n ti n th e w e l li s g e n e ra l layt theshoedepth.

l-

-

- [ Max.MW - DrillingMW I x ShoeWD x 0.052

-

DrilllngMW

-

Pressurein Casing Hydrostatic = (O.O52x MWx ShoeTVD)

-

Maximum(Fracture) Pressure at Shoe = MAASP + [0.052x MWx ShoeWDI

tI I

CopyrightReserved I

DrillingWell ControlManual

PTTCOLtd.

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Chapter3: Slow Pump Rate,Leak Off Test and MAASP

PAGE

7 o137

Erample: hole. Find the fracture pressure at the casing shoe (shoe Strength)? LOT : I.05tl psi HSP: 12 ppg X O.O52X 45OOft =

ZStlB psi

A F qfi tlr lll

tJ

f

Frac pressure = 1O5Opsi + 2BOBpsi

3 {t, I

= 3a5a psi

Formation strength gradient at shoe= : 0.8S7 psi/ft ;# But, PressureGradientof 7 ppg fluid = O.O52psi/ft.

Thus, Ma xi mu mmu d.tvetght:

o' 857 : 16.4 ppg b,g

= Fracture mudweightat shoe(ppg)

Eemple:Calculate the maximumallowablemuddensityof abovedata? 11.MAXIMUM ALLOWABLE MUDDENS|TY (ppg)=

Surf ace LOTPressure(psi) + LOTMud Density (ppg) ShoeTVD (f t) x 0.052 MaxMW :

10il -.r.12 : 4500x0.052'--

L6.49ppg

Answer: Max MudWei.ght : L6.4ppg 2noCalculationMethod:ConvertFracturepressureto EquivalentMud Weight(EMW) EMWis fracturemud weightin ppg (Maximumallowablemud weight) Max MW = 3858 psy'(0.052x 4500 ft) = 16.49 ppg Answer:Max MW = L6.4 ppg (roundeddown) Question:How to receivean accurateLOTpressure? Answer:- Goodhomo{eneousmud - Calibratedpressureg,augeCalibratedvolume measuring Saugeor tank - CorrectedCasin!,ShoeTVD - Incrementin$Pump mud into hotewith no return until formation beginsto Ieak D r i l l i n gW e l lC o n t r oM l anual

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Well Gontol tanual

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Ghapter3: Slow Rrmp Rfr, le*

ASP

PAGE

a{gf

(

?

Question;Why do we do LOT?

-

Answer: Becausewe needto calculate FormationStrengith(UsingLOTpressureto catculatethe maximumpressurethe formationcantemporarilyhandle,suchas circulatingout a kick) Example

?

= = =

Casingis set at Formationstrengthat the shoe Currentmud densitY

6,000 ft. WD 4,500 psi 11 ppg

€ -

MAXIMUMALLOWABLEMUDDENSITY(ppg)=

F

4500 ShoeStrength (psi) sh o e T V D( ft) x 0.052 6000x 0.052 = L4.42ppg= Max MW

-

(Psi)= 12.MAASP lMaxtmum Allowable Mud Density (ppil- Current Mud Density (ppdl x 0.052 x ShoefVD(f t)

V+.+z- LLppslx 0.052x 6000ft = L067psi

F F -

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Example:

F F

Fisue820.ffl3FU

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B75psr. 975psi l.0}0 psi. l.125psi gsi. 1"175

-

Detailed -{nahsis:

-

Tbeco'rrectansrer ts 8?5 psi.

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Chapter3: Slow Pump Rate, Leak Off Test and MAASP

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I t t t I t t t t t t t t t

PAGE

9 of37

SAFETYMARGINAFTERWELLSHUT.IN

:l

DR,ILLPIPEPRESSURE

CASINGPRESSURE

I a

lnitlalMAASP (Calculated flgure)

Shutln Pressures

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WellGontrolManual

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(Readon Gauge)

SafetyMarSn afterwellshut-in = MAASP-SICP

The safetymarginafter well shut-inis the amountof surfaceannuluspressurethat can be allowedto increasewhen start circulatingkick out of the well,withoutfracturingor mud injectingintothe formationat a shoe.In anotherword,the safetymarginafterwell strutin is the amountof the pressureon casin$pressuregaugethat can be allowedto kick out of holewhichis equalto the increasebeforereachingMAASPwhilecirculating pressure MMSP and SICP. between differencein (ttotq Safetymargin is more relevantas the influx travelsin the open hole and until it is insidethe casingshoe). ttft

The conditionthat would provide the hi$hest MAASPis; Whenthe formation shoe strenSthis a lot hi$her than mud HSP.

3"6

BOPSTACKKILLSHEETCALCULATION SAMPLEOFSURFACE

3"6.1 DetermineInitialCirculatingPressure(lCP) lnitialCirculating Pressureis the drill pipegaugepressurewhichwill be achievedwhen pumpwas broughtup to a desiredkill rateor a selectedslowpump rate.Thispressureis expressed as follows: (SCR)+ SIDPP (lCP)= SlowPumpRatePressure Pressure InitialCirculating

,

t t I

t t t )

t I )

3.6.2 DetermineFinalCirculatingPressure(FCP) Whilea kill mud is circulateddownfrom surfaceto the bit,the drill pipegaugepressure shoulddecreasedue to a heavykill mud replacingold mud in the drillstring.The Final as follows: Pressure can be calculated Circulating Final CirculatingPressure(FCP)=

tKMWt' x Slow Pump RatePressure(SCR) \ ** )

WellControlManual Chapter3: Slow Pump Rate, Leak Off Test and MAASP

PAGE

-

1O of 37

3.6.3 DetermineKill MudWeiBht(KMVU At the initialstageof well shut in when kick and the bit is on bottom,the bottomhole pressure have oncethe surfaceshut in pressures will be equalto the formationpressure Thisis becauseof well balanceitselfat the bottom.Thekill mud weight beenstabilized. (KMW)is determinedbasedon the formationpressurein orderto balancethe wellwhen carryout the killingoperations: SIDPP KMW= MW+l ( 0.052x TVDW eIl)

for the SurfaceBOPstack: Thefollowingis a sampleof KillSheetCalculation Well KickData: Holesize Ho l ed e p th 9-5/8" Casingshoedepth 5" DrillPipecapacity 5' HWDP(558 ft. long)capacity 6-7-/4"DC(722 ft. long)capacity MW

8-L/2" 12,860ft. TVDIMD LO,2O5ft. WDIMD 0.0178 bbt/tt. 0.0088 bbt/tt 0.0060 bbt/ft 13.9 ppg

AnnularGapacity: DCl OH oH/DP&HWDP DP/ Casing

o.0322bbt/ft. o.0473 bbt/tt. 0.0493 bbt/tt.

FormationStrengthtest data: LeakOffTestpressure TestMW Pu mp sOu tp u t SlowPumpRatePressure

2,020 psi 13.0 ppg 0.1070 bbllstroke 600 psi,at 30 SPM

-

(DYNAMICPRESSURE LOSS)

Shutin data; SID P P SIC P P i tGa i n

450 psi 680 psi L2 bbl

-

C o p y r i g hRt e s e r v e d I

D r i l l i n gW e l lC o n t r o M l anual

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t, t)

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International Well Control Forum SurfaceBOP VerticalWellKill Sheet (APl Field Units)

FOR{A fK) N S TR E N GT H DATA :

)

S-q,=A3E LEAK -OFF PRESSURE FROM : : R T I . A T O N S T R E N G T HT E S T t.r- I ,',E GHT AT TEST

ppg

Lr ,r, r.., r.l TLOWABLE MUD WEIGHT = (A) = ES r c E T V D E P T Hx 0 . 0 5 2

1

CURRENTDRILLINGMUD: WEIGHT

ppS

PPg

riH7lrrl IAIASP = C - :,RR:\T M U D W E I G H T )x S H O E T . V .D E P T H x 0 0 5 2

CAS'I{G SHOEDATA: SIZE

,

t t t t t t t t t t t t t t t t t t t t

PAGE

M DEPTH = ' _ r . f =\ r 3 1 D I S P L

\

T,V DEPTH HOLE DAIA: (PL) DYNAMIC PRESSURE LOSS [psi]

s_:i ruMP ;":-i ]ATA:

-- =-A=-UKUtrU , ]--I.IE

DATA:

LENGTH feet

CAPACIry bbls/ foot

SIZE

inch

M DEPTH

feet

T,V DEPTH

feet

VOLUME barrels

i1580 x0'0178 = 206.12 -' 558 x 0.0088 4.9t = x 4.33 722 0,0060

TIME minutes

slrokes

i PUMP STROKES

VOLUME

+

P U M PDISPLACEMENT

SLOWPUMPRATE

+

(D) 215.36

D R I L L S T R I N GV O L U M E

lP

PUMPSTROKES

(E)

20L2. strokes

HWDPx OPEN HOLE

1071 strokesll DP x CASING

10205 x 0"0493 =(c) 503.11 ' ll

35.7

srroKes

TOTALANNULUS VOLUME

TOTALWELLSYSIEM VOLUME ACTIVESURFACE VOLUME TOTALACTIVEFLUID SYSTEM

= 1r1 I 1o+xy

833.14 bbts

(J) I (l +J)

7786 strokes Dr No SV 04/01 {FieldUnits} 27-01-2000

t) I

) t a

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Min

D r i l l i nW g e l lC o n t r oM l anual

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Chapter3: Slow Pump Rate, Leak Off Test and MAASP

ts

PAGE

t:2ot37

tJ

-

r Surface

,1

lnternationalWellGontrolForum SurfaceBOPKill Sheet- VerticaltVell(APl FieldUnits)

rJ -

KICKOATA:

12

Ptt CRttt j

KILL MUD WEIGHT

-

SIDPP

CURRENTMUD WEIGHT

TVDx 0.052

450 = 14.57 12860x o.osz

KMW INITIALCIRCULATING PRESSURE

-

14.6 pps

-

1 DYNAMIC PRESSURE LOSS + SIDPP

-

= ..... ...{5..Q.......

tcP

KILL MUD WEIGHT

FINAL CIRCULATING

CURRENT MUD WETGHT

PRESSURE

''--

lfl

x DYNAMIC PRESSURE LOSS

= 630.22 x ...Y.YY-,.,.

FCP

630 x 100

(K) = ICP- FCP =

psi

= 2 1

-

STROKESPRESSURE

0

100 200 300 400 500 600 700 800 900 1000

1oqo

1029 r008 987 966 945 924

903 882

r100

861 84t) 819

1200

7q8

1300 1400 1500 1500

Tl7

1700 1800

1900 20r2

756 7iq

7L4 5S3 572

-

1;;

-

tfr o

-

ul t 3 at, tt. ul E A ul o-

-

E J 0t a I z

-

E .!i (J

-

o

F

65r 630

/-tl

FA ,1

STROKES.---.+

,'DrNoSV04/02(FieldUnits)27{1-2000

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WellGontrolManual Chapter3: Slow Pump Rate, Leak Off Test and MAASP

PAGE lil of 37

3.7

DETERMINE CHOKELINEFRICTION LOSSES ONFLOATTNG RtcS (suBsEABOp) On floatin$rigs,the effect of long choke line in deepsea water depth is verysignificant to the killingoperations. Thefrictionpressurein the chokelineand the kill lineappliesto all pointsin the well boreand is especially criticalat shalldwor weakcasingdepth. Thb problemcan be handledby measuringthe choke line friction pressurebefore driNling out of casin$.Thecasingpressurecouldthen be reducedby the amountof choke linetrictionpressurewhile bringingthe pump up to kill speed.The procedure to reduce casing pressureby reducingSICP down equal to choke line friction pressurewhile bringngpumpup to kill speedby meansof manipulating choke. Anotherway which normallyutilizedis to maintainkill line pressuregaugeconstant whenstartup the killingoperations. Tlrcreare three methodsto determinethe choke line friction pressure: 1) Performa Slow Pump Ratesby pumpingup throughMarineRiserand then up throughchoke line (chokefully openedwith well shut in). The differencein pressuresis the ChokeLineFrictionpressure. 2) Performa Slow Pump Ratesby pumpingdown the choke line and up to the MarineRlser.Thepumppressureis the ChokeLineFrictionpressure. 3) Performa Slow PumpRatesby pumpingdownthe kill line and up to the choke fine (close Annular/upper ram and lower ram, with choke fully opened).The ChokeLineFrictionPressureis 50% of the pump pressure. Thismethodwiil only applyif insidediameterof the kill lineand the chokelineare the same.

)

Choke line frictiontesf rnefhod I

)

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D r i l l i n gW e l l C o n t r oM l anual

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WellControlManual Ghapter3: Slow Pump Rate, Leak Off Test and MAASP

Thispagefor SubseaBOPStackOnlY

PAGE

L4ot37

( ( ( lJ

b

-

-:

"1

€ -

marineriserat 45 spmthe drillpipepressurereads450psi. up the chokeline? Calculatethe drillpipepressureat 45 spm ile circulating SLOWPUMP RATE D,ATA:

PUMPNO, 1 l{rser renOKe Gt ot{e Line Urre

-

Frta]tn

SPM

450

",

400

Answer:850psi

,b ,J

!

l anual D r i l l i n eW e l lC o n t r o M

aa b /

t t t t t t t t ,

t t t t t t t t t t t t t t t t t t t t t t t t t I I

P1T i,;

WellControlManual Chapter3: Slow Pump Rate,Leak Off Testand MAASP

15 of37

SAMPLEOFSUBSEABOPSTACKKILLSHEETCALCUI.ATION Thefollowin$is a sampleof KillSheetCalculation for the SubseaBOpstack: WellData: Holesize Air Gap(RKBto MSL) Waterdepth(MSLto Sea Bed) We l lMDfro m R K B WellTVD L3-5/8"Casingshoedepthfrom RKB t3-5/8" Casingshoedepthfrom RKB

L2-t/4" 80 ft. 770 tt. 13,000ft. 12,500ft. 9,200ft. MD 9,200 ft. TVD

l n te rn aCl a p a ci ti e s: 5 ' D r i l lp i p e 5" HWDP 4g2tt. 8" DrillCollar820 ft. 2 ' C h o k el i n e7 8 8 f t . 20" MarineRiser 756 ft. Mu dP u mpto ri gfl o o rvolum e

o.ot72bbt/tt. 0.0088 bbt/tt. o.oo77 bbt/tt. 0.0061bbt/tt. 0.3892 bbl/ft. 6.29 bbls

A n n u l aC r a p a ci ti e s: D ri l lC o l l a irn Op e nh o l e Drillpipe/ HWDPin Openhole Drilfpipe/ HWDPin Casing D ri l lp i p ei n R i se r

0.0837 bbt/tt. o.L2O4bbt/tt. o.L292 bbt/tt 0.3638 bbt/tt.

P u mpD a ta : PumpOutputat95o/o efficiency

O.L2bbl/Stroke

SlowPumpRateData: ThroughRiser@30 SPM T h ro u g C h h o kel i n e@30 SPM

450 psi 600 psi

Formation Strength: Formation StrengthGradientfrom Rotarytableto TVD= 0.750 psi/ft Otherrelevantinformation: ActivesurfaceMudvolume SeaWaterDensity

440 bbls 8.6 ppg

t

KickData:(wellkick and wasshut in @13,000'MD(12,500'TVD)

I

S ID P P

t I I

srcP

PitGain Mud Weight in use

350 psi 450 psi 10 bbls L2.7 ppg

'

t t I I

PAGE

CopyrightReserved

D r i l l i n gW e l lC o n t r o M l anual

Well ControlManual Chapter3: Slow Pump Rate,Leak Off Test and MMSP

PAGE

16 of 37

Subsea lnternational Well Control Forum

DATE:

SubseaBOP VerticalWellKill Sheet (APl Field Units)

NAME:

ffTCO Ltd.

.. CURRENTWELLDAIA:

FORMATION STRENGTH DATA: S U R F A C EL E A K . O F F P R E S S U R EF R O M

FORMATION TEST STRENGTH

i SUBSEABOPDATA: i MARTNE RISER ] LENGTH

MUDWEIGHTATTEST

FORMAIION GMDIENT= 0.75 psilft STRENGTH = ALLOWABLE MAXIMUM MUDWEIGHT tB)+

r{A) ^, SHOE TV. DEPTH x 0 052

=

] CHOKELINE PPS

INITIAL MAASP = ( ( C ) - C U R R E N TM U D W E I G H T )x S H O E T . V .D E P T H x 0 0 5 2 )

=

0,120

RATE DATA:

bbls/ strokei

30 SPM

-

: DRILLING MUD: ] WEIGHT

PUMPNO 2

Riser Choke Line

Line

Choke Line

i-T3-5/Bl in"n

M. DEPTH T.V DEPTH

HOLEDATA: SIZE T.V DEPTH

SPM LENGTH feet

ICAPACIry ibbls/feet:

l 1 6 8 8 x 0 . 0 1 7 2=

D R I L LP I P E

492 x 0,0098 =

H E V I W A L L D R I L LP I P E

-

\

/

M-DEPTH

450 600 1 5 0

PRE-RECORDED VOLUMEDATA:

-

PPg

-

srzE

bbls/ stroke

PUMPNO 1 Riser UNOKE Choke Line

I t""t

CAS"VGSHOEDATA:

(PL) DYNAMIC PRESSURE LOSS [psi] SLOW PUMP

[lRR

psi

I PUMPNO. 2 DISPL

PUMP NO. 1 DISPL.

] LENGTH

feer

VOLUME

1250d lreetPUMPSTROKES ]

barrels

Strokes

]

TIME Minutes

201.03 4.33

(E) 1764 strokesj

5B.S Min

820 x0,0837= 68.63

2 9 8 0 , 0 . 1 2 0 4= 3 5 8 . 7 9 DP x CASING

7BB x 0.0061 =

CHOKELINE

TOTALANNULUS/CHOKELINE VOLUME TOTALWELL SYSTEMVOLUME

(F+G+H| - {t) tD+t)= {Jt (K)

TOTALACTIVEFLUID SYSTEM

RrsER x DP i uenrrue

i

tJ+K)

756 x 0.3638=

4.81 + 1523.19 oots l/J{.$$ uutr 440

stroKes

12693 strokes

Min

423.1 Min

bbrs

2I74.BG bbrr

275.03

18124 strokes

Dr No SSV 04/01 (FieldUnits) 27{1-2000

-

ht Reserved

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PAGE

Ghapter3: Slow Pump Rate, Leak Otf Test and MAASP

b b b b b I t t I I I

Well ControlManual L7 ol37

Intemational Well Control Forum Subcea BOP Kill Sheet - VerticalWell (APl Field Units) (Jf,(

DA-A

'pri

350

{L- trlD WEGHT

12.7 :

450

MUDWEIGHT + CURRENT

{tfo _ = :

SICP ]

\ G

+

i psi

PrrcArN

10

banetsI

SIOPP TVDx 0.052

350 t3.24 12500x o.osz

1 3 . 3 pps l

DYNAMIC PRESSURELOSS + SIDPP

= -459. .-15_q.

I I

800

psi

x DYNAMIG PRESSURE LOSS

)

ll

b

t t

b

STROIGS

t

800 781 762 743 734

t I

705

t b

b b b

= 822 - 150

lpsil

I

b b b b

l N l T l A L D Y N , \ N I l C N l r \ A S P = I N l T l , \ L N I A A S P- ( I H O K E L I N E F R I C T I O N

PRESSURE

686

657 1000 1100 1200 1300 1400

1500 1600 1700

17u

648 629 610

59r

I b CL

r u ! E f ch tt I u l r L olu

g oJ J d

\

495

o () = : z o , .a ()

477 471

o

577

553 534 515

= 672 psi

,l

qrXe S,sygg02lE!98u!!!tsI4-a-! :2(p-0_,

plT

w e l lC o n t rM o la n u a l

I

Chapter3: Slow Pump Rate,Leak Off Testand MAASP I

PAGE

|

7Aot37

Thispagefor SubseaBOPStackOnly PressureLossThruRiser Why? ICP= SlDpp+ Oynamic Shutin kill giurr fin*

{ 5?o)sl

{. 9?0

Killlin*

I

, Pumpet ki|| r.r*

{

stcp tm

etFL 150psi

*

l',

't

$HP *

$fiPstlopri

ATsnr.fTlff milDrnofls

rt,tloo

,lSI^Hf

rltrr

AT KILL RATE CONDITIONS DP calculation = ICP+HSP-DPPL BHP 5720 = ICP+5200-400 = 5720-5200+400 ICP = 520 + 400 = 920 osi

8HP=$IOPF+*f$P * 5IO* 51fr1 = II2O# AnnularCalculation 700=5720-HSP HSP= 5020asi

AnnularCalculation = 700-150= 550psi CP= SKP-CLFL

BHP=CP+CLFL+HSP = 550 + 150 + 5020psi Assume: No APL at kill speed. = 5720psi Note:DPPL: DP Dynamicpressure Lossthru riser:400 psi

rl{ "{)

i 9?0 !:,,,.il.:Pump at Kill speed

' ICP = 520+ -{00 = 920 psi

\ *ra *tt

lrdl

t*d

tu

' StaticBHP = 5720psi Btrp= col{srAxT Dynamic BHP = 5720psi

At shut in conditions

At kill speed conditions (Assutnc:r\PL=Opsi)

t

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PTT

1.

WellControlManual Chapter3: SlowPumpRate,LeakOffTestandMAASP |I :1:i tgotgz

the drillstringVolume(bbls)and FromWelldiagrambelow,calculate annulusVolumein variouslocations: Givendata:-

Drillpipe

12,000'MD WellDepth B-t12" Holesize 9-s18" Casingsize Casingshoedepth 9,850'MD

Ce:ingrhoe

5" DrillpipeCap. 5" HWDPCap. 5" HWDPlength 6-Ll4"DCCap. drill pipe 6-L14"DClength Hevi-well Openhole Drillcoller

0.0173bbl/ft 0.0088bbl/ft 450' 0.0060bbl/ft 900'

0.0323bbl/ft DC/OHCap. DP,HWDP/OH Cap. 0.0473bbl/ft 0.0493bbl/ft DP/Casing Cap. Ignoresurfacelinevolume

of 5" drillpipe Capacity a) Totalinternal

bbls

of 5" HWDP Capacity b) Totalinternal

bbls

of 6-Ll4"DC Capacity c) Totalinternal

bbls

Capacity d) TotalDrillstringinternal in openhole of annulus e) Totalcapacity

bbls

in casedhole of annulus f) Totalcapacity

bbls

g) Totalannulus Capacity

bbls

CaPacitY h) Totalwellsystem

bbls

l anual D r i l l i n eW e l lC o n t r o M

Well GontrolManual

IT

PAGE

Chapter3: Slow Pump Rate, Leak Off Test and MAASP

2.

2Oot37

-"J

1, if TriplexPumphasbeenusedandit had Fromcalculated datain question pumpoutput= 0.10892 calculate bbl/stroke, totalstrokefor pumping mudto thefollowing sections: a) Stokesfrom Surfaceto the Bit b) Strokesfrom Bit to Casingshoe

t

c) Strokesfrom Casingshoeto Surface

3.

WellData: WellDepth L3-3l8"Casingshoe

7,560ft. MD. 6,000ft. MD.

7,050ft. TVD 5,820ft. TVD

= 1,400psiwith testedMW10.0ppg. A leakoff test (LOT)Pressure Bit size tz-r14" pipe Drill s" (19.slbift) Drillcollars 8" x2-t31I6",530ft. Annulus Drillpipe/casing Drillpipe/open holeAnnulus Drillcollar/open holeAnnulus

Cap.Cap.Cap.= Cap.Cap.-

0.01776bbl/ft 0.0080 bbl/ft 0.1293 bbl/ft 0.1215 bbl/ft 0.0836 bbl/ft

-

Mudweightin use

= 1 1 . 0p p g

Pumpoutput SCRat 30 SPM

= 0.119bbl/stk = 150psi

-

the volume,totalstrokesandtimein minutes to circulate at Calculate varioussections:

-

a) Internalvolumeof 5" drillpipe

-

bbls

-

-

b) Internalvolumeof B" DC

bbls

c) TotalDrillstringvolume

bbls

d ) Barrels of annulusin openhole

bbls

e) Barrels of annulusin casedhole

bbls

f) TotalAnnulus volume

bbls

s)Totalwellsystemvolume

bbls

h ) Strokesfrom surfaceto the bit

stks

-

-

!

C o p v r i s hRt e s e r v e d I

OrillinW e e l l C o n t r oM l anual

PTTCOLtd.

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WellGontrolManual

PIT

Chapter3: Slow Pump Rate,Leak Off Test and MAASP

PAGE

2tot37

shoe frombitto casing i) Strokes j) Strokefromshoeto surface

stks

k) Timeto circulatewith 30 SPMfrom sufaceto the bit; -minutes l) Timeto circulatewith 30 SPMfrom bit the casingshoe;-minutes

minutes

with30SPMfromshoeto surface; m)Timeto circulate

n) Whatis the maximumMWthat can be usedwithoutincurringlossesat shoe? ppg Answer pressure at shoe?-7'vxq-) o) Whatis the Formationbreakdown Answer

psi

p) Whatis the initialMAASP whenshutin wellwith currentmudweight (MW= 11.0ppg)? Answer 4.

psi

throughoutthe system,whatwould If the currentmudweightwas increased MAASP the be? a) Increase b) Decrease neverchange c) MAASP

5.

be recalculated? WhenshouldMAASP a) b) c) d) e)

6.

Startingeachshift Every500ft. drilled Everymudweightchange zone Whendrillingin transition All of above

Ratesmustbe takenwhen; SlowCirculating a) b) c) d) e)

of eachshift At the beginning Afterchangein drillingmudweight Afterdrillinga longsectionof hole(i.e.500') Afterpumpend repair All of above l anual D r i l l i n eW e l lC o n t r o M

PTTCOLtd.

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,;t-

Well ControlManual Chapter3: Slow Pump Rate, Leak Off Test and MAASP

PAGE

,--

22ot37

--1

7.

The casingshoeat 7,500ft. wastestedfor Leakoff with 12.5ppgMud.If the to a 0.91psi/ft.fracturegradient,how much leakoff pointwasequivalent pressure wasappliedor allowedat surface?

-,-J

arJ

a ) 1250psi b) 1500psi c) 1700psi 1950psi

B.

timebewitha 95 bbls.Drillstring to bit circulating Whatwouldthesurface pumpoutputof 0.123bbl/stkand26SPM? capacity, a) 20 minutes b) 30 minutes c) 40 minutes d) 50minutes

9.

1

tb -J

-

-

casing pressure to thecasing shoewhenthesurface is reached Thegreatest pressure is at itshighest. a) True b) False

1 0 . The fracturegradientof a surfaceholeformationat 4,500ft. is 0.606psi/ft. canbe closedin The drillingmudgradientis 0.495psi/ft.Howmuchpressure beforefluidis lostto the formation? a) b) c) d)

1000psi 450 psi 499 psi 600Psi

of 3,L20 1 1 . Whatmudweightwouldbe requiredto balancea formationpressure psiat a depthof 6,000'TVD.?

-

,ll1

F

a) b) c) d)

8.9 ppg 10.0ppg 9.5 ppg 10.2ppg

the mostwhenthe gas? 1 2 . Gascut mudreducesbottomholepressure

/

,F

a) b) c) d)

is nearthe surface is at or nearthe bottom is abouthalfway uPthe well all of the above

/ \ / t

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I I ,

Well ControlManual

PIT

Chapter3: Slow Pump Rate,Leak Off Testand MAASP

I

t i I ! !

PAGE

23ot37

whichoneis exerted system, in a circulating losses r3. Of allthesystempressure ontheformation? a) b) c) d)

t t t t t t t t t

lossin thesufaceequipment Pressure lossin theannulus Pressure lossthroughthe drillstring Pressure lossthroughthe bit nozzles Pressure

pressure is approaching theformation signaling at sudace indications Several is? these of Themostcommon the bottomholepressure. break a) A drilling gas b) Connection cuttings shaped thannormalor crescent c) Larger d) Totalmudlosses t

in the to thefrictionlosses whathappens aredecreased, if pumpstrokes annulus? a) Increase b) Decrease c) Staythesame What of 35SPM. at a pumpspeed of 1,200psiwasrecorded A pumppressure pumppressure of 30SPM? beat a speed willtheapproximate a) 1,029psi b) BB2psi c) 1,600psi d) 1,400psi

casingshoeat 3,640ryD;MW8.4 ppg; Surface information: Glventhe following leak Off TestpressureL,270psi(at test MW = 8.4 ppg). 17to 19; Answerthe questions fi.

Whatis the formationfracturepressure? a) 1270 psi b) 2,860psi c) 3,250psi d) 1590 psi

t Reserved

l anual D r i l l i n gW e l lC o n t r o M

T

cI

Well @ntrol Manual eac e Ghapter3: SlowPumpRate,Leak(Xf Testand MAASP I I z+agt

18. Whatis the maximum mudweightthatcanbe usedwithout allowable formation fractureat shoe? a) 13.6ppg b) 14.8pps !) ts.t ppg d) 16.0ppg

I I

I € € €

19.

witha mudweightof 9.0ppg. Drilling continues downto 4,500TVD/MD surface casingpressure Whatis the.maximum allowable at thatdepth?

i) r,tsopsi

I I F CI

b) 1,550psi c) 1,750psi d) 1,830psi

cF

pressure 20. Whendrilling with10.3ppgmudat 11,600 ft TVD.Theannular loss psi. pressure? is estimated at 195 Whatis the bottomholecirculating , a) 6,213psi b) 6,408psi t) 6,530psi d) 6,810psi

c. CF I C 4 F I €

4 ?/

Ir ?/

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I c 1 Reserved I

DrillinsWell ControlManual

PTTCOLtd.

WellGontrolManual Ghapter3: Slow Pump Rate, Leak (Xf Test and MAASP

PAGE

25at37

Exercise- 2 Answer 1

.

a b c d e f I h

t84.2 bbls 3.96 bbls 5.4 bbls 193.6 bbls 88.2 bbls 485.6 bbls 573.8 bbls 767 bbls

2

.

a b c

t778 strokes 810 strokes 4458 strokes

3

.

a b c d e f I h i j k I m n o p

L24.9 bbls 4.24 bbls L29.I bbls 169.5 bbls 775.8 bbls 945.2 bbls L074.4 bbls 1085 strokes L424. strokes 6519 strokes 36.2 minutes 47.5 minutes 2L7.3 minutes L 4 .6 ppg 4428 psi 1099 psi

4 . 5 . 6 . 7. 8 . 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20.

b c e d b b. c b a b b b b b c a b

Reserved I

OrillineWell ControlManual

PTTCOLtd.

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WellControlManual

l

--

Chapter3: SlowPumpRate,LeakOffTestand MAASP |l 2 :::i 6of37

/-at ---E

l*

-

BOPStack] KillSheetExercise'1 [Surface

l

,--' - t -

l

-

Well Data Holesize Holedepth Casingshoe,9-518"

(Vertical Well) 8-L12" ft. (MDrfvD) 12,860 ft. (MD/TVD) 10,205

Capacities Drillpipe,5" HWDP 4" Drillcollars,6-Lf

0.0178bbl/ft 0.0088bbl/ft 0.0060bbl/ft

-

l

,-

l

I I

Length Length

558ft. 722 fr.

--/

-)

Annulus CaPacitiesbetween:Drillcollarsin oPenhole in oPenhole Drillpipe/HWDP Drillpipein casing

0.0322bbl/ft

bbuft 0.0473 0.0493bbl/ft

Mud pump data

efficiency 0.107bbUstroke at 98%volumetric Displacement Slow pumprate data @30spm

F/

,-l

,-a

-

600Psi

FractureMud Weight at Casingshoe

16'8ppg

Kick Data The well kickedat 12,860ft. (MDffVD) = SIDPP = SICP = Pitgain MuddensitY=

/-/

450 psi 680 psi 12 bbls 13.9ppg

The well will be killed using the wait and weight method at 30 sPM' Ignore suface lines volume.

-

a-

F

/ l-

F

F

F

: / :

CopyrightReserved

l anual D r i l l i n sW e l lC o n t r oM

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/

WellGontrolManual Ghapter3: Slow Pump Rate, Leak (Xf Test and MAASP

PAGE

27 st37

QUESTIONS:1. How manystrokesto circulatefrom surfaceto Bit?

fromBitto Shoe? 2. Howmanystrokesto circulate

fromBitto Surface? 3. Howmanystroketo circulate

4. Whatis the KillMudDensityin ppg.?

(ICP)? Pressure 5. Whatis the InitialCirculating

(FCP)? Pressure 6. Whatis the FinalCirculating

with currentMud? 7. Whatis the MAASP

afterKillingwell? B. Whatis the MAASP

dropper100strokes? 9. Whatis the Pressure

circulation? to complete 10.Howmanyminutes

11.Whatis the SafetyMarginafterwellShut-in?

)

I I

Reserved I

DrillingWell ControlManual

PTTCOLtd.

Well@ntrolManual

T

I

Chapter3: Slow Rrmp Rab, Leak Off Tet and MJIAFiP I

PAGE

I zsorsz

4 I I I -u--

I I I I

BOPStack]Answer KillSheetExercise-1 [Surface 2,0L2(t ts1

-- ---

I,07L(tts1

a tt-

5,773(LLs)

I I I I

14.s7(14.6) 1050

a --

630

I cI ct

- 1,538 1,538.9 1,183-L,L67

a

e!

2L

CI I 4 C!

259.3(tro; Bs9

c-

C-

4

c-

e

CJ

c I c

ight Reserved I

OrillineWell ControlManual

I

pTTCOLtd.

WellControlManual Chapter3: Slow Pump Rate,Leak Off Testand MAASP

PAGE 29 of37

BOPStack] Exercise-2 KillSheet [Surface DATA KICKEXERCISE.WELL .'/ellDepth 13-3/8^CasingShoeat

7,560ft. MD. 6,000ft. MD.

7,050ft. TVD. 5,820ft. TVD.

A eakofftestwascarriedoutat the 13-3/8"shoeusinga mudweightof 10.0ppg.A of 1400psiwasrecorded. s.lrfacepressure B -.size rl r

nino

lr I aollars

12-114" 5" (19.5lbs/ft) 8 " x 2 1 3 1 1 6 ' x5 3 0f t .

l - p r p e / ca si nagn n u l u s h o l ea n n u l u s D' plpe/open D r c o l l a r /o o ehno l ea n n u l u s It.ludPumpto rig floorvolume

Cap.- 0.01776bbl/ft Cap.- 0.0080 bbl/ft Cap.- 0.1293 bbl/ft C a p . - 0 . 1 2 1 5b b l / f t Cap.- 0.0836 bbl/ft - 6 bbls

is shut-inwith the followingdata:."/ei1 SilDPP Si l C P K c k Vo l u me [ , l u dw e i g h it n u s e

5 5 0p s i 6 8 0 p si 25 bbls 1 1 . 0p p g

0 .119 bbl/stk. Punnp output ratePressure 500psi at 30 SPM Slowcirculation

For Drill Leveland SupervisorLevel: questions (onnextpage) thenanswerthefollowing KillSheetcalculation Complete Level: For Supervisor \,r/ell killsheet is to be killedusingthe Waitand Weightmethod.Usethe available pipe pressure as killmudis pumped thechangein drill a graphshowing andcomplete 1to on theseparatedGaugeproblemquestions the bit,andthenanswerquestions Topic). lvill be carriedoutwhengettingthroughtheWellKillingMethods

CopyrightReserved

/aa'

/

Well GontrolManual

/

Ghapter3: Slow Pump Rate, Leak Off Test and MAASP

PAGE 3{) of 37

/-A ,tt/

-

QUESTIONS:pressure? theformation to balance 1. Whatisthekillmudweightrequired

-

ppg to pumpkillmudfromthemudpumpto bit? 2. Howmanystrokeswillbe required

-

strokes

-

to pumpfromthe bitto the casingshoe? 3. Howmanystrokesarerequired

-

strokes

-

4. Whatis the MAASPat thetimethewellis shutin?

-

psl

-

5. What is the totalannularvolume?

-

barrels aroundthewell? 6. Whatis the newMAASPoncethe killmudhadcirculated

-

p sl 7. What is the finalcirculatingpressure,oncethe kill mud has reachedthe bit?

-

p sl

,,1

pressure? 8. Whatis the initialcirculating

-

psl

,1

g. Approximately killmudaroundthewellat 30 howlongwillit taketo circulate spm?

-

Minutes

t4

dropper 100strokesas kill 10.Thewellis shutin.Whatis thedrillpipepressure to the bit? mudis beingPumPed

,,-

psi/ 1OOstroke /-

11.Whatis the SafetyMarginafterwellshutin?

-

l anual D r i l l i n eW e l lC o n t r oM

PTTCOLtd.

t1

WellControlManual PAGE Ghapter3: Slow Pump Rate, Leak fff Test and MAASP II srogz

BOPStacktAnswer lfl SheetExercise-2 [Surface 1-

12.5 ppg

Z

1135 strokes

3-

'|.424 strokes

L

1090 psi

5-

945.26barrels

G-

635

psi

l-

568

psi

&

1050 PSa

9-

3m.9 minutes

- lO11-

4

psi/100str

410 psi

DrillineWell ControlManual

-

WellControlManual Chapter3: Slow Pump Rate, Leak Off Test and MAASP

PAGE

32o137

-

BOPStack] Exercise-l KillSheet [Subsea Well Data: Holesize Air Gap(RKBto MSL) Waterdepth(MSLto SeaBed) WellMDfrom RKB WellTVD t3-5l9" Casingshoedepthfrom RKB 13-5/8"Casingshoedepthfrom RKB Internal Capacities: 5" Drillpipe 5" HWDP 400ft. 800ft. B" DrillCollar 2-I3lt6" Chokeline820ft. 20" MarineRiser 800ft. Mudpumpto rig floorvolume AnnularCapacities: DrillCollarin Openhole Drillpipe/ HWDPin Openhole Drillpipe/ HWDPin Casing Drillpipein Riser Pump Data: efficiency Pumpoutputat97o/o ThroughRiser@ 40 SPM ThroughChokeline@ 40 SPM Formationstrength:

-

t2-L14"(Veftical Well) 76 ft. 724ft. 10,500 ft. 9,900ft. 6,500ft. MD 6,300ft. TVD

-

-

0.0L77bbr/ft. 0.0088 bbr/ft. 0.0060bbr/ft. 0.0088 bbr/ft. o.3886 bbr/ft. 5.0bbls

-

0.0829 bbt/ft. 0.1194 bbr/ft. 0.1288 bbr/ft 0.3626 bbr/ft,

-

0.119bbt/stk. 750psi BB0psi

-

shoeLeaked at 1,200psiwith 10 ppgmud. Casing

-

Kick Data: SIDPP SICP PitGain Mudweightin use SeaWaterweight ActiveSurfacemudvolume

-

400 psi 600psi 20 bbls 10.5ppg 8.6 ppg 460 bbls

F

-

questions: andanswerthe following Complete the KillSheetCalculations

-

t-

C o p y r i g hRt e s e r v e d I

l anual D r i l l i n gW e l lC o n t r oM

PTTCOLtd.

1

\ -

WellGontrolManual

PTT

Chapter3: Slow Pump Rate, Leak Off Test and MAASP

PAGE

3:l of 37

(pESTTONS: safetymarginat shoeafterkick 1. Pressure

psl

Z t{nd pumpto Bitstrokes

strokes

3. Elitb Shoestrokes

strokes

4. KillMudweight

ppg

(ICP) Pressure 5. f*Ual Grculating

psi

(FCP) Pressure 6. FnalGrctrlating

psi

Pressure 7. InitialDynamic Choke(casing)

psi

strokes 8. Riserdisplacement

strokes

9. f,lMSPafterkill

psi

10.Pressure drop/100strokes

psi

- Choke) 11.Cydetimes(surface

minutes

12.Elitto surfacestrokes

strokes

Reserved I

OrillineWell ControlManual

I

pTTCOLtd.

Well @ntrcl

T

Chapter3: SlowPumpRate,Led(trTd

ild ffAP

BOPStacklAnswer Exercise-l KillSheet [Subsea

IJ ::= {t:rl ( (

1.

435 PSi

€

2.

1495 strokes

3.

3768 strokes

C ?

4.

( 1 1 . 3P) P g 11.28

5.

1150 PSi

6.

806

7.

470 PSi

B.

2437 strokes

9.

780

PSi

10.

24

PSi

11.

286.3 minutes

12.

9998 strokes

-

F ? ? €

PSi

?

c. ? ? F F F F F F F F F F F F F F ? ?

4

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WellControlManual Ghapter3: Slow Pump Rate,Leak Off Testand MAASP

PAGE 35 of37

BOP Stack] Exercise-2 KillSheet [Subsea lYell Data -''{oe size *o e deoth C;singshoe,9-518"

B-r12" 11,850ft. (TVD/MD) B,BB0ft. (TVD/MD)

C-apaciUes -lea'"n/ lveightdrillpipe,5" l- coltars, 6-112"x2-l3lL6" ID lro,ke|tne,2-112" '.1anne riser

0.0172bbr/ft 0.0088bbl/ft 0.0077bbl/ft 0.0061bbl/ft 0.3892bbl/ft

Clos€dEnd Displacement Dr olpeclosedenddisplacement

0.0254bbl/ft

AnnulusCapacitiesbetween:l" collars in ooenhole in openhole f- pipeiHWDP in casing -r" pipeiHWDP l- oioein riser

0.0292bbr/ft 0.0447bbl/ft 0.0478bbl/ft 0.3638bbr/ft

t-

i l 3 t D e .5

l.lud pump data volumetric efficiency D sclacement at 98o/o Slow pump rate data 345 spmthroughRiser 345 spmthroughChokeline

Length Length Length Length

837 ft. 1,116ft. 5s3 ft. 540ft.

0.12bbl/stroke

880psi 1,000psi

Other relevantinformation Activesurface 460 bbls volume Formationleak off test data with 10 ppgMud leakoff testpressure Surface

2,100psi

Kick Data -tr'he well kickedat 11,850ft. (TVD) = SIDPP = SICP = P i tg a i n MuddensitY=

580psi 870 psi 1 5b b l s 10 PPg

The well will be killed using the Wait and Weight method at 45 spm

I'

C

ftt Chapter3 tu

e e 4 e

€

EE

L-CTd

rd IIISP

PAGE $d37

4

QUESTIONS:

(

1. Calculate the amountof extrapressure thatcanbeapplied, in thisstatic condition, beforethecasingshoebreaks down.

€

e ?

2. Howmanystrokes arerequired to pumpkillmudfromsurface to the Bit? 3. Howmanystrokes arerequired to pumpfromthe Bitto Casing shoe? 4. Howmanyminutes is required to circulate thetotalwellsystem? 5 . Howmanystrokesare requiredto displace the marineriserto killfluidbefore openingthe BOP?

e F ? ? ? F ? 7 -

Whatis the kill mud density?

-".

7 pressure (ICP)? 7. Whatis the initialcirculating

; -

pressure (FCP)? 8. Whatis the finalcirculating

-

9. Whatis the initialdynamiccasingpressure at killpumprate?

-

F

10.Whatis MMSPaftercirculation of the killmud?

-

11. Calculate the pressure dropper 100strokeskillfluidpumpedinsidethe drill string.

-

C C -

C -

CopvrishtReserved

W e l lC o n t r oM l anual

PTTCOLtd.

a !

?

WellGontrolManual

PIT Is

Chapter3: Slow Pump Rate,Leak Off Testand MAASP

PAGE

37 ol37

XillSheet Exercise.2 [SubseaBOPStack]Answer 1,226psi 1,536strokes 962 strokes 130 min I,637 strokes 11

ppg

1,460psi 962 psi 750 psi 1,662psi 32

psi

D r i l l i n eW e l lC o n t r o M l anual

PTTCOLtd.

Chapter4

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WellGontrolManual

PIT

t t t t t t

Chapter4: Reductionin HydrostaticPressure 4.t

=

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o

-

V'

E

o

t0n

-

? 4 4 1 1 1 2 4 El

a

El

a

Il

a

E

Edlon ltrle fnssrE @lP) Iheq SIP =0.052rg 6r l0 =5 psi

Drill string in a well bore can be comparedto a U-tube,wheredrillstringis one limb of U-tubeand annulusis another limb. This U-tubeconceptdescribesthe well system where the bit is on bottom and it is possibleto circulate. As illustratedin the drawing,the left side of U-tuberepresentsthe drill stringand the annulus.lf Uthe rightsiderepresents tubecontainsmud densityof 9.6 ppgand has the columnheightof 1O ft. thus the hydrostaticpressureat the bottom of Utubewill be balancedat 5 psi.

lf we filleda heavierdensityof fluid intothe drill string,we shouldsee a lighterdensity f l u i d d r a i n e do ff th e w e l l o n a n annulus side.The certainvolumeof pit gain can be noticed after stop pumping the heavier densityfluid into drill string.The certain emptypipe is also noticedat top sectionof t h e d r i l ls tri n g .

Lightermudwillbedmined offin orderlo balarttthe lqflnstalicprcssunat thc bsnomin flaliccondilion.

a

E

a

E

a

E

tt

E

a

E

a

F -

4 -

t? hl

t

1of2O

U-TUBE CONCEPT

-

t? a?

PAGE

This is becausethe well stabilizesitself at the bottom of the well. Therefore,the bottom hole pressurestays the same as longas the heavydensityfluid is still in the drillstringafterstop pumping. T h i s p r a cti cei s si mi l a rto a p u mpingslug into holepriorto comingout of hole.

Blttrn HolcPnrun il6iliz:d

rT

Well ControlManual

PAGE

Chager 4: Reduc{ionin HydrostaticPrcssure

-

When shut in well, there is no escapeof fluid out of the well.Thewell balancesitself at the bottomhole.

-

lf well containsthe same fluid densityin both dr ill str ing and in annulu s , the hydrostaticpressureat the bottom on both sides will be the sam e and is bal anc ed. Therefore,the shut in pressuresat the surfacewill be equalto zeroon bothsides. -

Bdlomhde tressre (BlP)

hdetressreFlP)

-

BtF m brlh d&s = 0.052r 10r 6,000 = 3,120psi psi(balanced) BHP= 3,120

-

lf the well containsa differentfluid densities, the bottomholepressure equalizes itselfandwill be balancedat pressure the hydrostatic of the higher fluiddensitycolumn.Therefore, the pressure hydrostatic on lighterfluid densitycolumnwill createan extra pressureon surfacepressuregauge,in orderto compensate for the lossof pressure hydrostatic in that column.

rti4.t2s

-

EoumHprsr(E?}

m(HrR

8HP : 0.052x 12.5x 6000: 3900psi psi(balanced) BHP= 3,900

BHP balanceon bothside: 0.052x 12.5x 5,000: (0.052x 10 x 6,000)+ 780

-

-

-

h\

t E

WellControlManual

E E

PAGE

Pressure Ghapter4: Reductionin Hydrostatic

t

3 of2o

EI t h t E

42

OUTDRYPIPE DUETOPULLING REDUCTION PRESSURE

t E t

ts

Whenpullingout pipein dry the volumewhichis taken condition, out of the holeis the volumeof pipe only. metaldisplacement

t

E, t rhi

t lF,

t

l f th e h o l ei s n o tfilledthe fluidin the well will dropat nearsurfaceor at belowthe rotarytable.

lr\ E lrrr. lr rt-

rel="nofollow">- :rg )ry

Thedroppinglevelof fluidhappensin the spacebetweencasing(or marine riseron floatingrig)andthe pipe (Casi ngllRiser metaldisplacement Gapacity- Pipemetaldisplacement).

Before pulling pipe

After pulling pipe dry withoutfilling hole

rl-t

rF

from a formula reductiondueto pullingout pipedrycan be determined Thepressure as follows:

F

r-r

Pressuredrop per foot (psi/ft)=

l-

!-

iv'lw(ppg)x 0.052x !-

PipeMetal Disp.(bbl/f t) ement (bbl/ f t)l fCsg / Riser Capaci.ty(bbl/ f t) - Pipe lriletal Di.splac

t-

rrr-l IE

rF

rrrr-

Example: Determinethe hydrostaticpressuredecreasewhenpulled DRYpipeout of the hole; = 5 No.of standspulled = 92ft. Averagelen$thper stand PipeMetal Displacement = 0.0O75bbl/ft. = 0.O773bbl/ft. Casin!,Capacity = 77.5 pp€, Mud Wei$ht

psi/ft=1L.5x0.052 x

0.0075 = 0.0643 ( o . 0 7 7 3- 0 . 0 0 7 5 )

r-

rr. E rE ts

Thus,total pressuredrop due to pull out pipedry =

0.0643 x 5 x 92

= 29.56 psi

WellGontrolManual PAGE

Ghapter4: Reductionin FfydrostaticPrcssure

4.3

4of 2O

DUETO PULLOUTWETHPE REDUCTION PRESSURE the Whenpullout pipewet condition, volumewhichis takenout of the hole is the volumeof pipemetal andthe volumeof mud displacement insidepipe.Thepullingwet condition occurredwhenthe BHAequipped with a downholemotor,turbineor a restrictorsubfor the MWDwhich preventmud to fall downfreely.

-

Thedroppinglevelof fluidhappensin the spacebetweencasing(or marine riser on floatin$ rig) and the pipe HuidGnnotFa' closedend displacement. Pulling Wet

from a formula reductiondue to pullingout pipewet can be determined Thepressure as follows:

l-

Pressuredropper foot (psi/ft)= Mw(ppg) x 0.052x

PipeClosedEnd Disp.(bbl/ft) - Pipe ClosedEnd Disp.(bbl/f t)l lCsg/Riser Capacity(bbllf t)

Example: Determinethe HydrostaticPressuredecreasewhenpulled WEf pipeout of the hole: - 5 No.of standspulled Avera$elenSthper stand = 9 2 f t . = O.O!776bbl/tt. PipeCapacity PipeMetal Displacement = 0.OO75bbl/ft. = O.O773bbl/ft. CasingCapacity = 71.5 ppg Mud Wei$ht p si /ft = 1 1 .5x 0 .052x

+ 0.00751 10.01,776 = 0.2903 6 + 0.007s)l 10.0773(0.0177

Thus,totalpressuredrop due to pull out pipewet =

O.29O3x 5 x 92

= 733.54 psi

-

while pickin$ up the bit to shutin Question:Shouldthe pumpsbe kept runninS, on a kick? Answer:Yes,to maximize the pressureon the bottom of the hole with ECD.

t-

I

,-t

PTTCOLtd. ,r'

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E

Well GontrolManual

PIT

rf E

Pressure Chapter4: Reductionin Hydrostatic

E

PAGE 5 of20

rr E

Example:

E

44 bbl/tt : O.O7 Casingcapacity Drillpipecapacity :0.0188 bbl/tt bbl/tt O.OO77 Drillpipesteeldisplacement: Fluiddensity11.6 ppg in BHP? lf pulling670 ft DP"wet",Whatis the reduction

E

-{ E E E

-

WETPIPE(psi/ft)= DROPPERFOOTTRIPPING 21.PRESSURE

'-

(bbl/f t) Drtlting Mud Density (ppg) x 0.052 x closedEnd Di.splacement Ri.seror CasingCapactty(bbl/f t) - ClosedEnd Displacement(bbl/f t)

-t

I t . 6 x 0 . 0 5 2 x ( 0 . 0 1 8 8+ 0 . 0 0 7 7 ) = 0 . 3 3 3 6p s t / f t -

'-

-t -t

+ 0.0077) 0.074 (o.o1BB in BHP : 0 . 3 3 3 6p s i / f t x 6 7 0f t Answer: Reduction - 2 4 4p s i

E

rt

-t -t

AND PIPEBACKONBOTTOM DUETOSTRIPPED CHANGE 4.4 PRESSURE OPERATION ONSTRIPPING CALCULATION VOLUME

-,

4 4

-t ra -,

In this case,the pressurechangein the well shouldbe noticeddue to movement of pipeand the changein colum nhei ght of kick. The bottom hole pressureand shutin casingwill increaseas a result.

r'

r' ts

lf the kick doesnot migrateupwardthen the formationpressurewill be constant. will be usedas a Thisformationpressure for the determination referencepressure pressure in the well and at change of the surface.

-t H -

I' b'

l anual D r i l l i n eW e l lC o n t r o M

ba \

When well is shut in after kick durin$ tripping out, the bit is off bottom. Commonpracticeis to strip the bit back on bottom in order to allow circulating kick out of the well.

a

WellControlManual Chapter4: Reductionin llydrostatie Pressure

PAGE 6 of2o

When strippingthebit back on bottomwhen well was shut in with Annular BOP,it is common practiceto bleedoff mud in the well throu!,hthe choke in order to compensatefor the new volumeof new pipeat surface. Volumeof Mud to be bled off: = PipeClosedEnd Displacement x StrippedLenSth Volumeof Mud to be filled in Pipe: = PipeCapacityx StrippedLength Note;Thiscalculationis appliedto all BHAruns evenlf there is a float valveinstalledor withoutfloat valveinstalled. Seeadjacentdiagram.

Example: WellTVD 10000ft CapacityDC/OH0.0299bbl/ft CapacityDP/OH0.0456bbl/ft CapacityDP/C0.0555bbl/ft Drillcollar1250ft longx 6-1/2inchOD DC capacity= 0.00777bbl/ft = 0.0323bbUfr DC metaldisplacement Drillpipe5000ft long4.5 inchOD DPcapacity= 0.01667bbl/ft = 0.0071bbl/ft DP metaldisplacement Calculatethe volumeto bleedoff if 1120feet of drillpipeis strippedbackinto the hole? = 0.01667+ 0.0071 Closeend displacement = 0"02377bbl/fr Answer:Volumeto be bled off = fi24 ft x 0.02377 bblJfi = 26.6bbl

Shrn in wilh &rx.dar tlOP

IiJ

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PIT I1

h I

Well GontrolManual Chapter4: Reductionin HydrostaticPressure

t

PA(=E

h

7 ol20

.t I I

Example:

-t E t

WellTVD 10000ft CapacityDC/OH0.0299bbl/fi CapacityDP/OH0-0456bbUft CapacityDP/C0.0555bbl/fi

E I I Il II

ShLt irulh ArnlrAOF

Drillcollar1250ft longx 6-112inchOD DCcapacity= 0.00277bbvft = 0.0323bbl/fi DCmetaldisplacement

IT

rt E

Drillpipe5000ft long4.5inchOD DPcapacity= 0.01667bbl/ft = 0"0071bbl/ft DPmetaldisplacement Lengthof a stand= 92 ft

il -l il

floatvalveare lf 15standsof pipewithan installed of mud must be pumpedto keepthestringfull? barrels how many stripped,

tl

-

Lengthof strippedDP = 15X 92 = 1380fi Answer:Mudbe pumped= 1380fi X 0.01667bbl/fi= 23 bbl

= rl ll

rl -

4.5

rl

OUTREMAINING COLI-ARS/BHA DUETO PULLING PRESSURE REDUCflON Theremainingdrillcollarsor BHAare the lastfewjointswhen it was completelypulledout,it meantthat thereis notingleft the mud leveldropin the well at surface in the well.Therefore inside casing or marineriseronly. happened

!l !l !l

rl

of the pressure dropdue to pullingout the Thedetermination remainingDCor BHAcan be carriedout as follows:

-i

-

Volumeof DCIBHA(bbls):Pull Drycondition: = DCIBHAMetalDisp.(bblft) x DCIBHALength(ft)

-

Mud LevelDrop(ft) = Volumeof DCIBHA(bbls)+ Casin€i(Riser) (bbllft) Capacity

-

Pressuredrop (psi)dueto pullingout remainingDCIBHA = 0.052 x MW (ppg) x Leveldrop(ft)

il

IT I

\ t

CopyrightReserved

/

IT

WellGontrolManual PAGE

Chapter4: Reductionin tlydrostatic Pressure

8 of20

E
LevelDrop in feet

-

2 x3O xO.O298

o.o773

= 23 ft.

= O.O52x 71.5 x23 = !3.75 psi

Iotal PressureDroP

-

euestion: During POOH,the wettboretake improper holefill-up. The bit ts 9OOft bottom.Whatrs the bestpracticeto do in this case?

from -

Answer: -Runa flow check -lf flowin$, the well will be shut-in immediately Jf no flow,run backto bottom& monitorpit Sains -Circulatebottoms up and record returnsfor any swabbedkicks 4.6

-

OUTPIPE DUETOPULLING PRESSURE LOSTOFOVERBALANCE

-

Overbalancepressure = Bottomholepressure- Formationpressure For normal drillingoperations,oil company has a specificoverbalancepressureto work on in orderto maximizethe drillingefficiency. SbticBHP= 5,408psi Formation For instance,150 to 200 psi over balance 0verBalancing pressure. by208psi Pressure

t0,000nwD

-

From drawin$,the over balancepressureis as follows: determined -

Overbalancepressure = (0.052x 10.4 x 10000) - 52OO = 208 psi.

-

l anual W e l l C o n t r oM Drilling

PTTCOLtd.

-

PIT

WellGontrolManual Ghapter4:Reductionin lfydrostatleprcssure

PAGE 9 of2o

I'

b b rf r"

-t -

-t

Example: PumpfailedwhilePOOHresultedin mudleveldropof 700fi and wellstartsto flow. MW:11.7ppg,TVD:11500ft Whatis the BHPwhenttrewell startsto fl ? what is the heightof mud levelwhenthe well startsto frow? 1.

HYDROSTATIC PRESSURE(psi)

Mud Density(ppg) x 0.052 x TVD (ft)

-

1 1 1 1 1 1 1 1 4 4 4 4 4 4 -

4

- 700) HSP= 11.7X 0.052X (11500 = 6571psi Answer:The BHP= 6571psi Answer:Theheightof mudlevel= 11500- 700 = 10800ft

consideronlythe caseof pullingout pipewithoutfiilingthe wert: Themaximumlengthin feet of pipethat couldbe pulledout beforeloosingoverbalance pressure shallbe determined as follows: Lengthof Pipe pulledDRYto loseOverbalance (ft) _ overbalance(psi) x (Riser/casing cap - Metar Displacement) MW x 0 .052 x Metal Displacem ent

-

4 -,

And Lenglthof PlpepulledWETto toseOverbatance (ft) _ ouerbalance(psi) x (Riser/casing cap - closed End Displacement) MW x 0.052 x ClosedEnd Displacement

-

-t rt = = =

? ? \

t

D r i l l i n gW e l lC o n t r o M l anual

;tJ

Well ControlManual

PIT )

PAGE

Chapter4: Reductionin HydrostaticPressulre

10 of20

E
Lengthof PipePulled DRY

= 2,334 ft. _ 150 x10.0773 ( 0.01776 0.007s) l 1 1 . 5x 0 . 0 5 2x ( 0 . 0 1 7 7 6 +0 . 0 0 7 5 )

Lengthof PipePulledWET

= 576.8 ft.

4.7

-

-

PUMPINGSLUGPRIORTO PULLOUTOF HOLE

ffi

Main lssues:

Level&op <

Lengthof slug Lengthofslug {

I I

Triptmtircrew

Pum ping slugis the same Oncethe conceptof a "U-Tube". pumpingstoppedandthe Kelly or TopDrivedisconnected, therewill be leveldropin dry pipein the dr illstr ing whi l ea pit gainoccurredin the TriP Tank.

-

Leveldropin drillstringis affectedby the differencein densitybetweenslu$and dr illingm ud,andvolum eo f pumpedslug. Oncethe slughas beenin positionafterstoppumping,therewill be no changein the itselfand balancedat the bottomhole. Thewell "U-tube" BottomHolePressure.

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PAGE

h,

Lloe 20

t

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t t

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4.7.L

Barrelsof Slug Requiredfor a DesiredLenglhof Dry Pipe

,

h

t E t E

-

Length of dry O,O"_

t

Length of slt'tg

,

rtt

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t E

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E

n

tucc__

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E

for a desired lengthof drypipe Barrels of SlugRequired Stept insideDrill Pipe h1 Pressure drop(psi)required Hydrostatic = 0.052x DrillingMW(ppg)x Lengthof drypipe(ft)

-

Step2: in Pressure Gradient(psy'ft)betweenSlugweightandMudweight Difference

E

,

-

= (slugyvt.ppg- mudwt. ppg)x 0.052

t

E E

Drilling

a

,

Step3: Slug Lenglh h2 (ft)

E

,

F

,

Drilt pipe(psi) Hydrostatic pressure drop required" iLnsid.e

,

Dif f erencetnpressuregradient(pst.f t)

t E E t h

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E

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T

Step4: SlugVolume(bbls)= Slug Length(ft) x Drill PipeCapacity(bblft)

:'

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n t E

11 t

E t h\

t

SlugVolume(bbl)for a givenlengithof DryPipe Length of Dry Pipe(f t) x Pipe Capacity(bbl/f t) x Mw(pps) SIug Density(ppg) - Mw(ppg)

/ aJ

Well ControlManual Chapter4: Reductionin HydrostaticPressure

|t :oo= lJ2st2f.

1

-

for thefollowingdesiredlengthof Determine the barrelsof slugrequired Example: DryPipe: DryPipe(2 stands)= L84' , MW- 9'2 ppg, SluEWeight= L3.2 ppg, Driffpipecapacity= O.OL422bbl/ft Pressure Step-l Dropin Hydrostatic = 0.052x 12.2x 184 = Lt7 psi

Lengthof DryPipe*

I t-

Step-2 Differencein PressureGradient = (13.2- 72.2)x 0.052 : 0.052psi/f t

Length of slug

Step-3SlugLength(f0-h2 LL7 = 2250ft' 0^052 Step-4SlugVolume(bbls) = 2250 x 0.0L422 = 32.0bbls

Drilling Mud

-

SlugVolume(bbl)for a givenlengthof Dry Pipe

-

184x0.0].4ZZxL2.2 L3.Z- L2.2

-

E x a m p l e : 2 5 b b l o f h e a v ys l u gw a s p u m p e d ,f o l l o w e d b y 1 5 b b l o f d r i l l i n gm u d : WellTVD 10000 feet D r i l l i n gM W 1 2 . 6p p g H e a v ys l u g d e n s i t y1 4 . 9 p p g D r i l lp i p ec a p a c i t y0 . 0 1 7 7 6b b l / f t S u r f a c el i n ev o l u m e 1 0 b b l C a l c u l a t teh e m u d l e v e ld r o p i n t h e s t r i n gw h e n t h e w e l l h a se q u a l i s e d ?

-

-

Slug Denstty (ppg) -1) Stusvotume(b$ x ( Drilling Mud Density (ppg)

1)= 4.ssbbt

Answer : Mud Level Drop =

-

-

(bbl)= 28.PJTGAINDUETO SLUGU-TUBING

,s x (H-

-

4.56

-

:257 feet

0.0r776

-

-

WellControlManual Ghapter4:ReductlonIn lfydrcstaticRessure 4.7.2

for a DesiredLenglhof DryPipe Weightof SluERequlred

Steel Lengthof Slugin DrillPipe(ft) Slug Volume(bbl) Drill PtpeCapacity(bbl/f t) Step-2 Pressurerequiredto givedesireddrop Hydrostatic insideDrillPipe(psi)

Ilillirp iid

- Mw(ppg) x 0.052x f eetof Dry Ptpe

Weightof Slugrequiredfor a desiredlengthof DryPipe.

Step-3 Weightof Slug(ppg)

- MW(pps)+

Hy dr ost ati.cPr es sure(psi) 0.052x Slug Length(ft)

Weightof Slugrequlredfor a desiredlengthof dry pipe:

b b

SlugVolume(bbl)for a given lenglthof dry pipe Length of dry Pipe(f t) x Ptpe Capactty(bbllft) x MW(ppg) SIug Denstty(ppg)- Mw(ppg)

b b b

b b b b b b b b

b b

b

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Chapter4: Reductionin Hydrctatic Pressure

14of 20

-

Weightof slug requiredfor a desiredlengthof pipe with a set volumeof slug (continued) Example: Determinethe weightof slugrequiredfor the followingdesiredlengthof dry pipe: = Drypipe(2 stands) 184 feet = MudWeight L2.2 ppg = Volumeof slug 25 bbl = O.OL422bbl/tt Drillpipecapacity

lfl

Step-1Lengthof Slugin DrillPipe(ft) Length of dy pipe Volume of slt,lg

,

25 :M'=

l1

! 7 5 8f t

-

Step-2 HydrostaticPressurerequiredto givedesired dropinsideDrillPipe(psi) = 12.2x 0.052x 184 = LI7 pst Step-3 Weightof Slug(ppg)

L 2 . 2+

l-

-

t1.7 = L3.5ppg ( 0.052x 1758)

SlugVolume(bbl)for a givenlengthof DryPipe:

-

184 xO.OI422 x12.2 25= SIug Density (ppg) - 12.2

-

x O' 814' 22x l2' 2 sl u g D e n si ty( pptD- !2.2 = ' 184 2S

-

-

-

= 1.3 SfugDensity= 1.3 + L2.2ppg = 13.S ppg

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Ghapter4: Reductlonin HydrostaticPressure

15of 20

t .t

E

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4.73

SI.UG OFPITGAINAFTERSTOPPUMPING BARRELS

t

Et E

t

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Ir

a

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Il

a

Il

a

E-

4 El E =l Il

-

mud gaineddueto purnpingtheslugand

TI

MW Slug t lumeofslug

E

:12.6 p =14.2p : bbls

II

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4 -,

4 4

lumeof Dry

EI

Thus.

4 4

of DryPipe

0.CI17

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PAGE

16of 20

--A -1

lJ t-

,-

WELLDATASHEET: Holedepth Holesize 9-518"Casingshoe Mudweight

,J

,-

12,000ft. TVD/MD

B-r12"

1

6,200ft. TVD/MD L2.4ppg

-

DRILL STRINGCAPACITY:

I

Drillcollars, 850ft. Drillcollar Drillpipe Drillpipe

Capacity Metaldisplacement Capacity Metaldisplacement

0.0077bbr/ft 0.0300 bbl/ft 0.0178 bbuft 0.007sbbr/ft

-

ANNULARCAPACITY: pipe Casing/Drill pipe Openhole/Drill hole/Drill collar Open

-

Capacity Capacity Capacity

0.0476bbr/ft 0.04s9bbl/ft 0.0292bbr/ft

-

-

CASINGAND OPENHOLECAPACITY:

Casing 9-518" B-Llz"Openhole PumpOutput Average standlength Rate SlowCirculation

Capacity Capacity = 0.102bbUstk = 94 ft. at 30SPM

-

0.0729bbr/ft 0.0702bbr/ft 400psi

-

-

questions 1to 16: UsetheDataaboveandanswer -

1. Whatis thestaticbottomholepressure? Answer:

psi

I

,I

reads3,800psi. at 100SPMthepumppressure 2. Whenthepumpis running pressure losses are250psi,whatis the Dynamic bottomhole If annular pressure? Answer:

tr-

rJ i

,.-

psl

f

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Chapter4: Reductionin llydrostaticPressure

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(ECD)? Density Circulating #2, whatis theEquivalent to question 3. Referring Answer:

ppg

to question#2 , if pumpspeedis reducedfrom 100SPMto 4. Referring be? B0SPM,whatwill the pumppressure

-

? r" r" t"

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1 llt

-t 4 4 4 4 2 ? r"

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-t T ? -

2

Answer:

psl

5. If 12 standsof pipewerepulled"dry"withoutfillingthe hole,whatwould be? the reductionin bottomholepressure Answer:

psi reduction in BHP

6. If 6 standsof pipehadbeenpulled"wet",withoutflllingthe hole,thenthe wouldbe? resultantlossof bottomholepressure

Answer:

psireduction in BHP

7. Howmanycompletestandsof pipecanbe pulled"wet",withoutfillingthe is 240psi hole,beforethe well startsto flow?The overbalance

Answer:

stands

If the holehadbeenkeptfullwhilepullingpipe,butthe collarswerepulled "dry" withoutfillingthe hole.Whatwouldthe resultantreductionin bottom holepressure be?(totallengthof collar=850ft)

Answer:

psi reduction in BHP

Slugof 14 ppgmudwill be 9. In orderto pullpipe"dry",a 25 barrels intodrillpipe.Asthe slugisjust beingpumpedintowellat a displaced whatwill bottomholepressure slowpumpspeedandwellis notequalized be? dueto the addedMudweight a) Increasing due to the U-tubingeffect b) Reducing fairlyconstant c) Remaining

n 4 l? -

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I Well ControlManual PAGE

Chapter4: Reductionin llydrostatic Pressure

laof 2()

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to question#10, oncethe Slugof heavymud is in position 10. Referring will? andthe top driveis removed,bottomholepressure

\

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dueto the heavymud a) Haveincreased to the U-tubingeffect due reduced b) Have fairlYconstant c) Remaining

,--

-r-

#10, ll.Referringto question

-

oncethe slugis in position? a) Whatis the volumeof pipeemptied,

Answer:

-

bbls

-

is the lengthof emptypipewhenslugis in b) Whatapproximately position?

Answer:

-

-

feet

pressure of a formation to balance mudweightwouldberequired 13.What ft.? 7,987psiat 12,000 Answer:

I

-

feet

(providedthat no pipeis in hole)could LZ.I1lossoccurred,howfar theoretically The overbalanceis the fluidleveldropbeforethe well is underbal-anced? 240psi.Themudweightis 12.4ppg + v'*

Answer:

-

-

ppg

-

Casingis beingrun.if the last10jointsarenot filled that 9-518" 14.Assume failed,whatwould valvesat the pipe/collar with mud,andif the non-return pressure be? the reductionin bottomhole

-

Lengthof I joint of casing =42 feet =0.0744bbl/ft of casing Capacity Casing/Annularcapacity =0.0622bb|lft(hole/casing) -I2.4 Mudweight PPg a) 250Psi b) 148Psi c) 270 psi

,-

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15.ADrilleris preparing to pullout of the holeandhaslinedup to the Slugpit. He intendsto pumpa 15 barrelsheavySlug,followedby 10 barrelsof drillingmudfromthe activepit. WELLDATA: Depthof hole MW Heavyslug DP.Capacity Surfacelinevolume

9,000' 12.0ppg 14.0ppg 0.0L776bbl/ft 6 bbls

Howfar will the mudlevelin the stringdropwhenthe well hasbeen equalized?

IE

a r-

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F t

a ) t7r ft. b) 141ft. c) 153ft.

F a F. a

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16.The26" strfaceholeis beingdrilledat 1100'TVD fromsurface, the formationpressure is exactly595 psi.Whatis the formationpressure?

rt

rt F I r-L

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-

a ) Normal b) AboveNormal c) BelowNormal

lT.Calculate gascut thereduction in bottomholepressure whencirculating mudinthefollowing well: WD WeII Surface to 650ft. 650ft. 1,300ft. 1,300ft. to bottom Original mudweight

6,000' MW=10.0ppg M W = 1 1 .p0p g MW=11.5ppg = 1 1 . 5p p g

a

a) 83 psi b) 92 psi c) 67 psi

F

F

F

18.Whichof the following (Twoanswers) increase the riskof swabbing? whiletrippingout a) Pumping Low viscous mud b) c) Balledup Stabilizers d) Trippingout too fast

lF F E E rt E

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Ctrapter4: ReducillonIn lSrcstatic Pressure

PAGE

20of

Exercise-3Answer L.

7738 Psi

€ (

2.

7988 Psi

€

3.

L2.a ppg

4

4.

2432 Psi

5.

83.4

6.

189 - 193

7.

7

8.

225.5 Psi

€

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Psi

€

9

.

Psi

stands

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c

LL.

a b

3,23 bbls 181.5 feet

L2.

372

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L4.

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Well ControlManual

PAGE Lot27

Ghapter5: Kick& Shut-inPrccedure

5.1

DEFINMONOFKICK

A kick is definedas an unscheduled influxof formationfluidsflow intothe wellbore.Fluids enteringthe wellborecan eitherbe liquids(oilor water),gasor a combination of thesefluids. Someimportantpointsto considerin well kicks: r

Fluidsproducedduringunderbalanceddrillingare not considered kicks.

o

Fluidsproducedduringa DSTare not consideredkicks.

,

a e ,

4' 1' t

e e a

Conditlonsfor a kick to occur: o

Formation(pore)Pressure rel="nofollow"> BottomHolePressure(BHP).

o

A reasonablelevelof Permeability (> 10 milli-darcy.) and porosity> LOo/otor sandstoneand > 5o/o tor limestones)of that formation. - Theabilityof rockto allowfluid movementor flow througha rock. Permeability

2 2 l,

t

e 4' 4 ,

2

a ,

e '

a 2 ,

a 2 2 t

- Theamountof spacein the rockthat may holdthe fluids. Porosity o

Thatfluidcanflow by its nature.

Note: Thesymbol) meansgreaterthan.

Kicksmay alsooccurwhile: .

D ri l l i n g .

.

Tripping.

.

Makinga connection.

.

Logging.

o

R un n i n g ca si n g .

o

Cementing.

lYhv doesa kick occur?

oreis to

Pw
NippleUp(N/U)or NippleDown(N/D)BlowoutPreventer (BOP),etc.

I

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Well GontrolManual Ghapter5: Kick& Shut-inPrccedures

5.2

PAGE

-

2ot27

OFKICK CAUSES Causesof Kick(Wellborelnflux) flow of formationfluidintothe A "Kick"or "WellboreInflux"is an undesirable pressure pressure is morethan hydrostatic wellboreand it happenswhenformation in wellbore. Severalcausesof Kick (Wellborelnflux)are listed below: -

1. Lackof knowledgleanclexperienceof personnel(Humanerror)- Lackin$of wellcln causewellcontrolincidentbecausetheyd-on'thaveany trainedpersonnel may ideaswhatcan causewellcontrolproblem.Forexample,personnel pumplighterfluidintowellboreand if the fluidis li$htenough, accidentally reservoirpressurecan overcomehydrostaticpressure.

,-

2.LightdensiUf|uidinwe||bore-|tresu|tsindecreasin$hydrostaticpressure. areseveralreasonsthat cancausethis issuesuchas: . Lightpills,sweep,spacerin hole . A cci d e n tadli l u ti o no f dr illing fluid

-

. Ga scu t mu d -

3. Abnormalpressure- lf abnormallyhi$hpressurezonesare overcurrentmud kickwill occur. weightin the well,eventually 4. Unableto keepthe holefull allthe time while drillingand trioping.lf holeis not pregsure will decrease. fullwithdrillingfluid,overallhydrostatic

-

- Dueto lostcirculation in formation,if the well couldnot 5. Severelostcirculation . pressure will be decreased be keptfulfyfifled all the time,hydrostatic pressure of drillingfluid usuallycausedwhenthe hydrostatic Lostcirculation Thereare severalfactorsthat cancauselost formationpressure. exceeds suchas: circulation - mud weightis too heavyand too viscous. . Mud properties

-

_ -

. HighEquivalent Density Circulating . Highsurgepressuredueto trippingin holeso fast . Drillingintoweakformationstren$thzone

,-

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PAGE

3ot27

Chapter5: Klck&Shutin Prccedures

6. Suabbing causesreducingwellbore hydrostaticoressure. Swabbingis the conditionthat happenswhenanythingin a holesuchas drillstring, loggingtool,completionstlng,etc is pulledand it bringsout decreasinghydrostatic pressure. whilepullingout of holeby closely Anyway,swabbingcan be recognized monitoringholefill in trip sheet. Gestlon: lf a well is drillingwith water basedmud hasa problemof completeloss of returns, rfiat should be the next step to do? Answen Fill this well with water.

Qpsfion: While drilling, the flow meter dropsfrom 6o0/oto 50o/o. What shouldbe causeof this? Arrcrrer: This well has partial lost circulation.

53

EARLYKICKSIGNSATSURFACE

531

While Drilling

o

Drillingtrendsand or drillingbreak(Rateof (ROP)increasewhiledrillingintohigh Penetration pressurezonedue to lessresistanceto the bit).

o

Increasein torqueand drag(Swab associated).

o

Decrease in shaledensity.

o

Changein cuttingshapes.

r

Increasein chloridecontentin mud.

o

Increasein flow linetemperature.

o

SampleShaleGuttings

, r l . r t . t , l Normally pressuredshales

pressuredshales Abnormall.v-

lncreasein background or Connection Gas.Whilewe are drilling,thereis a stablegasreadingthat is not connected with eitherbottomsup gas or drilledgas is generallycalled"Backglround Gas".The

Reserved Copyright

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Ghapter5: Kick& Shut{nPrccedures

4ot 27 F-

t-

-

gasalwaysshowseverytime whiledrillingand it is not a signof background riskto wellcontrolsituation. Nevertheless, considerable we mustalwayscheck gasvaluebecauseit is ableto helprecognize changesin background underbalance

F\ aJ ! \ tt-

drillingintohighpressure situationwhiledrilling,especially zone.

-

A certainamountof the gasin cuttingswill enterintodrillingfluidwhenwe drill throughporousformationsthat containgas.Thegasshowingon the surfacedueto driflingthroughformationsis called"DrilledGas".

'-

* -

Whengasfrom the cuttingcomesinto drillingfluid,it will expandas it is circulated out of hole,hence,youwill seethe gasfrom the monitorsat the flow line.Eventhoughwe pressure haveoverbalance hydrostatic exertedby mud column,gasshowingon the surfaceby this mechanismalwayshappens. Youcannotrisemud weightup to make it

-t-

-

-

-

disappear.

-

Drifled gasshouldbe recordedin mud logchartagainstformationidentification. In addition,the gas unitshouldrepresent changesin drillingrate(rateof penetration) throughporousformation.

v -

Practically, if we seea lot of drillinggas,we shouldstopdrillingand attemptto levelpriorto drillingahead. circulategasuntilit reachesto an acceptable

I

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Well ControlManual

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Ghapter5: Kick&Shut-lnplocedures

b tt

Lf !t

BackgroundGas

tt Lt b b It b

b f't ft r'

rt 2 It rt 2

1 2 I 2 I

a I 2 t

t

5ot27

DatatoLoggingUnit Memb'rane gasextractorpositionedin the&illing mudrehrmline.

53

FOSITIVE KICKSIGNSATSURFACE PositiveKick(WellboreInflux)Indications Positivekick (wellboreinflux)indicationsmean inbication-s showingalmost LOOo/okick (wellboreinflux)intowellbore.

5.41 WhileDrilling PositiveKick lndicatorsWhile drilling 1- Increasein flow show - Withoutany increasingin flow rate in, increasein return flow indicates somethingcomingintowellborewhiledrilling.Therefore, flow show instrumentprovidedby the rigsor servicecompaniesmustbe checkedand calibrated frequently. Becausedrillingfluidsystemon the rig is a closedsystem,increasing in flowshowwithoutadjustingflow ratein will causepit

Drilling WellControlManual

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Ghapter5: Kick& Shut-inPrccedures

I

/ -

gain in a pit system.Nowadays, with hi$htechnologysensors,detectingchangein pit at the rig site.However,visuallycheckthe pit levelis levelis easilyaccomplished Sometimes, chan$ein importantas wellfor doublecheckingfigurefrom the sensors. pit levelmay be detectedafterthe increasein flow showbecauseit takesmoretime .

F -

,J

I

volumeenoughto be ableto detectby pit sensors. to accumulate 3. Contlnueflowingwhile the oumpsare off - When pumpsare turnedoff, bottom holepressurewill decreasedue to lossof AnnularPressureLosses(APL)and Equivalent CirculatingDensity(ECD).lf thereis anyflow comingafter pumpsoff, it formationinfluxintowellbore. indicates

,-

F F

Thereare severalreasonswhlch miBhtcausethe well to flow when the pumpsare off : o

fluid(Kick)enteringthe wellboreas a resultof the swabbin$actionof Formation U-tube(wellflowingfor certaintime). the drillstring.Thisis dueto unbalanced

/ -

o

Ballooning or fracturecharging(wellflowin$for certaintime).

-

o

Takenotethat Kickcan be checkedat surfacewhileTRIPPING.

f

-

With the pumpsoff, the frictionlossesin the annuluswill disappear.BottomHolePressure will be droppedequalto that AnnularPressureLosses.

l-

F

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PAGE 7 ot27

4. RrmpSPMIncreasebut pumppressuredecrease.

"Rtmp SPMincreasebut pump pressuredecrease"may be a positivekick sign at surface. llud PumpPressureis extremelyimportantto the drillingprocess.The Mud Pump Pressure whiledrilling.Anyunusualchangein Gaugeenablesthe drillerto monitorthe pressure pressurewill alertthe drillerof downholeproblems.Pressuretoo low couldindicatewashed joint or brokendrill string,worn pump packingor liners,or lost out pipeor bit nozzle,loose retumsdueto formationbreakdown.Pressuretoo highcouldindicatea pluggeddrill bit or an providesan Reliableindicationof mud pumppressure increasein mud densityor viscosity. problems, enablingthe drillerto makecorrections avoidingmajor earlywarningof circulation ptoblems.REMEMBER: Whenevera kick is suspected,do a FLOWCHECK! gas(increase in backtroundgas)is observed? Quution:Whatwouldyoudowhenconnection Answer: Flowcheck

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PA(3E

8ot27

/ /

I I l1 ,|J

(wellborebreathinE Well balloonlnE or microfracture)

aJ

-

What is well ballooning? Thewell ballooning effectis a naturalphenomenon occurring whenformationstake drillinE mud whenthe pumpsare on and the formationsgivethe mud backwhenthe pumpsare off. What is mechanismof well ballooning? Whilepumpsareon,if Equivalent Circulating Density(ECD)exceeds formationfracture,micro fracturesare createdand drillingmud will loseintosmallinducedformationfractures. The microfracturescan be propagatedand it may causea lot of mud volumelossesdownhole. Microfracturewill not causeseverelossesor totallylosses.

11

I ,a

1 ,F ,-

henpumps areon

/-

ECDmore thanfo ation

,l-

/-

F

t-

/ t,/

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Ghapter5: Klck&Shut{n Prccedures

PAGE

I ot27

Whenpumpsare off, the ECDwill reducebecauseannularpressurelossbecomes zero.Theinducedmicrofractureswill closeandthe drillingmud willflow backinto a wellbore

are off

Mudfl

b b b b b b b b b b b b b b b b b

p

backbecausemicrofracturesare closed.

Theballooning can happenintoanyweakformations. not onlyat the casingshoe. Sometimes,mud flow backfrom formationscan bringgasor formationwaterwith the mud thereforeyou may see gas peakor mud contaminatedwith waterwhile circulatingbottom uP.

Howto ldentifyWell Ballooning

It is notsimpleto identifywell ballooninE becausethe wellactsalmostlikewell control situation(takingkick).Therefore, thistopicdescribehowto identifywell ballooning and importantruleswhenyoufacewith well ballooning situation. ThesefollowingEuidelineswill help you identifyballooning. . Drillin€mud losses- you must havemud lossintoformationin orderto havemud flow backwhen pumpsoff.

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-

. Flowbackwhen pump off and flow rate decreaseovertlme - you must line the well up into a trip tank and monitorwell.Trackingvolumeflow backeveryminuteshelpyou understand if flow backtrenddecreases. Thekeything is "flow backrate must reduceovertime".lf not, youwill havewell controlsituationinstead.Monitoring welltakestime and personnel must be patient. . The more mud you lose,the faster flow back is and the longertime willtake beforethe well is static (flow completelystop). . Mud flow back from formationscan bringElasor reservoirwater with the mud thereforeyou mayseegaspeakor mud contaminated with formationwaterat the samedepthwhile circulating bottomup.

-

r1 Jf

tla

BALLOONING EFFECT:

ta

BALLOONING IN THEGULFOFTHAII.AND

I

-

What is Ballooningand Howto Handlelt -Ballooning occurswhenthe formationtakesin mud with pumpson - thengivesit backwhen the pumpsare off (a functionof the Equivalent Circulating Density- ECD)

-

-Rockmechanics showsballooning resultsfrom smallfractures in sandsand shales(usually thin bedded), openingand closingas the pumpsareturnedon and off (microfracture p h e n o m en o n )

-

HowTo Operate

-

-

-

-Hofesizein production zone6 L/q"OH

-

-Annular velocities for holecleaningduringfast drillingequatesto highECDs

-

=1.0to 1.5+ PPG) (ECDs

-

HowTo ldentifyBallooning

-

-Firsttime or anytime youare not sureit is Ballooning - treatbackflow as a kick

t-

Youmust identifynormaloperations

-

- Volumeincreasewhenstoppingpumps

-

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\ 'o l u m ed e cre a se w h e nsta rti n $p umps

You must identify mud losses(must lose mud before ballooningcan occur) - l - o s s e so c c u rw i t h p u m p so n

tt ft tt tt tt

t{ t{ t{ tt ft

tt tt tt tt tt tt tt

Flow back when the pumps are turned off - D e c r e a s i n og v e rt i m e - f : h e r v e l li s s h u t - i nq u i c k l yS I C P= S I D P P( C u t t i n g sl o a d i n ga n d g e l s t r e n g t h sm a y c a u s e : r ' e s s u r e tso d i f f e rS I C P< S I D P P ) - ! ! ' n e nc i r c u l a t i n gb o t t o m su p , y o u m a y h a v ea g a s p e a k o r w a t e r c o n t a m i n a t i o n from the : : p t h o f b a l l o o n i n g( p o s s i b l ed i s p e r s i o n ) . -tileasure v o l u m ep u m p e df o r p e a k t o r e a c ht h e s u r f a c ea n d b a c k c a l c u l a t ed e p t h o f :alloonino $r kick RULES BALLOONING UNTILYOU'REABSOLUTLYSURE- TREATEVERYFLOWBACKAS A KICK - S h u t - i tnh e w e l l - l ' : u l a t ei t o u tu s i n gt h e D r i l l e r 'M s ethod BallooningProcedures- What To Do lF The Well May Be Ballooning . e

A l w a y sT r e a tI n i t i a lF l o wb a c k a s a K I C K ! ! ! ! l f b a l l o o n i n gw a s e s t a b l i s h e dp r e v i o u s l y ;

- R e c o r dS I D P Pa n d S I C P( S I D P Pm a y b e i m p r a c t i c adl u e t o D P f l o a t & $ e l s ) - ContacS t u p e r i n t e n d e natn d d i s c u s sw h a t h a s h a p p e n e d

t,

Lt tt tt L,

- AccuratelyGaugeFlow Back (Shouldhave been done on everyconnectionprior) - D e t e r m i n et o t a l B B L Sl o s t t o f o r m a t i o n - D o n o t P O O Hw h e n w e l l i s B a l l o o n i n g 1 . W i t h w e l l s h u t - i n r, e c o r dS I C Pa n d S I D P P( m a y b e i m p r a c t i c adl u e t o D P f l o a t & g e l s ) 2 . R e c o r dp i t v o l u m eu s e df o r k i c k t o l e r a n c ec a l c u l a t i o n

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€ ( € ( €

pressure 3. Throughchokeline,bleedoff a pre-determined volumeof mud or designated but lessvolumethat usedto calculatekicktolerance 4. Allowpressure to stabilizeand recordSICP,SIDPPandvolumebleed- lf pressure is greater thanthe first readingproceedwith the firststepof the DrillerMethod

-

- lf pressureis lessthan the first reading,proceedto step#5

-

- lf the pressureis equalto the first reading,it mayor may not be ballooning (volumesbled and pressure will influencenextdecision 5. Bleedoff an additionalpre-determined volumeof mud or pressureincrement

la -

- lf totalvolumeto be bledis greaterthan kicktolerancevolumeand/or pressures havenot dropped,you needto treat as a kick)

-

6. Allowpressure to stabilizeand recordSICPandSIDPP

-

- lf pressure is greaterthanthe first readingproceedwith the firststepof the DrillerMethod

-

-

- lf pressure is lessthanthe first reading,proceedto step#7

-

- lf the pressure (volumesbled is equalto the first reading,it mayor may not be ballooning and pressure will influencenextdecision)

-

7. Repeatsteps4 and5 increasing bleedvolumesor pressures, increases confidence that pressures Ballooning is occurrin€lwhen and returnbleedratedecreases

-

8. OpenAnnularand observewell,continueoperations.

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-

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5.4i! WhileTripping PqsitiveKick IndicatorsWhile Trippingl Thereare2 positivekick indicatorswhiletrippingas listedbelow; L Trb loe dwiation such as short fill uo whlle trioplngout and excessoit gain while trlpoing h Fortrippingoperation,it is veryimportantto havea fillingsystemvia trip tank that holefill at all times.With utilizingthat system,we cancomparefluidthat fovides continuous 'E filledin or returnedfrom wellborewithsteelvolumeof tubular(drillpipe,drillcollar,BHA, pipedisplacement while trrbangcasing,etc).lf drillingfluidvolumeis lessthan theoretical tripptngout or morereturnfluidwhilerunningin,you needto flow checkand monitorthe well. r

lf flowcheckindicateswellboreinflux,crewmust quicklyshutthe well in.

r

lf flowcheckdoesnot showanyinflux,drillstringmust be run backto bottomin order to circulateat leastbottomsup to ensureholecondition.

2 Positiveflow when plpe is statlc.Everytime that pipe in staticcondition.Triptank with conectfillingsystemmust be monitoredat all time by both rig personneland mud logger.lf personnel mustconfirmflow checkand prepareto shutthe volumein trip tank increases, well in. Question: Thehole failed to take 7 bbl of mud from the trip tank while POOHwith bit at 77OOft from bottom.What is the next step to do? Answer:Flow check.If no flow, trip back to bottom,monitor the return mud volume,then circulatebottomsup. 5.5

SUMMARY OFKICKINDICATORS lndicator

Significance

Drillingbreak

M edium

lncreasein mud returnrate

High

Pit gain

High

Flowwith pumpsoff

Definitive

Pumppressure decreaseand rateincrease

Low

in drillstringweight Increase

Low

Gascuttingor salinitychange

Low

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Ghapter5: Kick& Shutin Prccedures

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-

5.51 Kick InfluxRate

o

lt is extremely important to detecta kickearly,to minimize itssize.

o

lf a kickis suspected,Run a flow check !

-

-

5.52 KickSize- KickToleranceis the maximumvolumeof gas kick in barrelsthat we are ,ab|etosuccessfullyshutthewe||inandcircu|atethekickoutofho|ewithoutb formationstrengthat shoe. o

Undermostconditions a 10 barrelkickcan be handledsafely(butdepending on company's kicktolerancedesign,rig equipments and rig crewability).

o

An exception is slim holedrilling,whereevena smallkick occupies a largeheight in the annuluscreatingexcessive shut-incasingpressure.

-

o|nf|oatin$dril|in$,wherethevesse|moVes'smal|kicksaremoredifficu|ttod Therefore, shut-inwellwith Hardor FastShut-inprocedures is recommended to reducesizeof kick. lf a Kick is suspected.

-

o

Lift the drill string until a tool joint is just abovethe rotarytable.

.

S h u t d o w nt h e m u d p u m p s .

o

Checkfor flow.

-

lf a Flow check is positive, o

-

-

"

lf flowing- open the HydraulicControlRemote(HCR)valve,shut in AnnularBOP, and closethe choke (Soft Shut-in).

o

RecordsIDPP and slcP.

.

Recordpit gain and depth (MD and TVD).

o

Note the time for monitoringinfluxmigration.

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Chapter5: Kick& Shut-inPrccedures

below: for Pit GalnsandFlowRatesto detectklcksare presented Rdatedequipments

Plt Volume Totalizer (PW) showspit galnor loss.Pit levells a $oodkick indlcator

Rrd(.d eilphf

I

Pumpwith automatically

pumpmudfrornbip tank to annulusinorderto keepthe holetull Float tlpe pit level sensor

Fit lsvelincreasernay indie

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I

Whatis a trip tank? tJ

TripTankis a smallmetaltank with smallcapacityabout2O-4O bblswith 1 bbl divisions

-

insideand it is usedto monitorthe well.Thereare severaloperations that we can usethe trip

1

tank to monitorthe well as follows:

F-

lr

l-

l-

1. TripOutof HoleOOOH):Whiletrippingout of hole,the trip tank is usedto trackvolumeof mud replacing volumeof drillstring.Thevolumeof mud shouldbe equalto displacement

-

volumeof anykindof tubulartrippedout of holeas in the calculated trip sheet(if the hole

-

failedto take the mud from the trip tank,the holemay havea kick,so we mustdo the flow

-

check).

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2. TripIn Hole(IlH):Whiletrippingin hole,the drillingstring(bit,BHAand drillpipe)is ran backin the hole,the trip tank mustbe usedto keeptrackvolumegain.Theexpectedvolume gainshouldbe equalto the displacement volumeof wholestring.

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3. FlowCheckThetrip tank is utilizedto determinewellconditionin orderto see if the well is stillunderstaticcondition.

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The importanceof trlp tank is as follows: L Rronidesufficient hydrostatlcpressureto preventinflux from reservoir.When TOOH,mud will be lostbecausemud volumemustsubstitutedrillpipevolumepulledout of hydrostatic hole.lf hydrostaticpressuredecreasestoo much,influxfrom reservoircan come into the hole and makea troublein wellcontrol.Forthis reason,mud in trip tank mustbe filledintoholeto rnaintainhydrostaticpressure. 2 l{id{ IndicatonVolumeof mud from the trip tank is pumpedin the holecan be an indicator that relatesto a situationoccurringin wellboreas kick.lf the volumeof mud measuredby trip tank is lessthanthe expectedvolumeof drillpipevolumetrippedout of hole,the suspect volumeof mud. problemis kick becausevolumeof kicksubstitutes The dmrlation systemwhile tripping a trip tank pumpwill circulatemud intoa bellnipplein WhileTrippingOutof Hole(TOOH), mud will returnbackto the trip tank. orderto keepthe holefull all the time andthe over-flow Onceeverystandis pulled,the mud volumein the wellwill decreasebecausethe drillpipeis pulledout of hole.Sincethe trip tank pumpis alwaysrunwhiletripping,the annuluswill be full all the time,with knowntrippedvolumefilledamount.Failureto fill the holewhenpulling out piperesultedin the mud levelin the holedroppingand causingthe wellto flow.

tUhat is flow check? suchas drilling,trippingpipeand circulating Flowcheckis the periodthat youstopoperations and monitorthe well in orderto seewhetherthe well is staticor not.Thetime for flow check shouldbe enoughto confirmthe statusof a well.lt mightbe few minutesor it couldbe as require15 manyoperators on the wellsituation.Normally, longas 30 minutesdepending minutesflow checkif the well is in normalcondition.

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FJ

Howto executethe flow check?

-

1. Stopthe currentoperationas stopdrilling,trippingpipe,circulating, etc. -

2. Spaceout pipeat rotarytable.We needto do it becauseif the well is flowingwhileflow

-

checking, we can immediately shutthe well in. -

3. Monitora welleitheron a trip tank or withouttrip tank.lt is preferable to monitorthe well on the trip tank becauseit cantell whetherthe wellis givingor loosingfluidwhilemonitoring.

la

,-

4. lf the well is in staticconditionthat meansno increasein volumein trip tank or flow at flow

-

line,youcan continueyourcurrentoperation. lf the well is flowing(youwillseevolume

-

increasein the trip tank),youneedto stopand attemptto figureout howto kill the wellor do

-

somethingelse.

-

FlowShow:Drille/s first indicationthat the well is flowing

-

Mud R€turnLinB flow

Mud f,ow out paddle

-

500,6flow

-

-

-

+-

-

SPACEOUTPIPEAT ROTARYTABLE

/ l

a"l -

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Lg ot27

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ft

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RotaryTable

it

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ts E -t it ht bt

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Hardshutin: lt meansthat whiledrillingchokelinevalves(HCR)are in the closedposition;it will be openedafterthe well is shut in.Thehardshut-inis the fastestmethodto shut in the rvell:therefore, it will minimizevolumeof kick allowedintowellbore. SoftShutln: lt meansthat whiledrilling,the chokelinevalves(HCR)are in the closed position.Upona kickdetection, the HCRis thenopen,followedby shuttingin the BOPand allowsfluidto flow then closethe chokevalvesto shut in the well.Thesoft shut in procedure shut in.Thisis the bad part throughthe surfacechokelinebeforethe wellwill be completely becauseit doesn'tminimizethe sizeof the wellboreinflux.The of the softshut in procedure You needto followyourcompanypolicy shut in procedureis the companyspecificprocedure. is recommended becauseit to shutin the well.Anyway,the 'HARDSHUTlN PROCEDURE"

1 E rt ! !

b \

HardShut ln and SoftShut In whenwe talk aboutwell control,thereare2 typesof shut Forthe drillingindustryespecially in. namelythe HardShut-inandSoftShut-in.

t

allowsus to shutwell in as quicklyas possibleand kick volumeenteringintoa well borewill be minimized.Pleasealsorememberthat the lessvolumeof kickyou havein the well bore, the lessproblemyouwill seewhenyouattemptto kill the well.

Well ControlManual & Shut{nPrccedures Chapter5: Klc{<

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( ( /: (

I- HardShut-in

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2. Soft Shut-in

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Hardshut-inprocedure

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Lineup for Soft shut-in S

fi'

s U F F E R T A N K

t{

Lt tt tt Lt Lt tt Lt tt tt tt Lt Lt Lt tt tt Lt Lt Lt Lt

Choke line nranual valve HCR een HCR.& Choke Line b

Bpen Close Open

Remote Choke

Open

l-ine frorn Ghoke to $rlGS {shaker} Open

I

Shaleshaker

Softshut-inprocedure

QhIVI:fN {whileCnf{inq} rf,

iI

BOP lrrturably Annulrr BOP)

. Clc*c r*motr Chokc .Rrcord S|DPPandSICP

Shaleshaher

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PostShut-lnProcedureswhile Drilling -

Thereareseveralfiguresthat must be recordedafterthe well hasbeenproperlyshut in in caseof a wellcontrolsituation. Readand recordthe shut-incasingpressure(casinggauge). Shut-lnGasingPressure(SIGP): In orderto get the properpressure reading, the casinggaugeshouldbe installedupstreamof the closedchoke. Shut-lnDrlllpipePressure(SIDP):Readand recordthe shut-indrillpipepressure. Youmust rememberthat whetheryou havea floatin drillingstringor not. ff thereis no a float is in the drillstring, the shut in drillpipepressure can be readdirectly from the standpipemanifold. you needto bumpthe float in orderto determinethe lf thereis a float in the drillstring, correctshutin drillpipepressure. Time:Recordthe time that the wellcontrolsituationis occurredand keepan accuratetime logfor the entirewell kill operation. Recordthe closingpressure of BOP.In orderto preventwell borefluid ClosingPressure: leakingthroughBOPelements,the closingpressure shouldbe highenough. Pit Gain:Readand recordthe pit gain.Pit volumegainedis verycriticalfor the maximum casingpressure calculation. Youshouldcheckthe volumegainedfrom mud loggerand driller in orderto get the accuratefigure.Also,comparedatafrom otherdatasourceif available. Afterthe well is properlysecuredand all informationiSgathered, the supervisor on the rig proper shouldinformhissupervisor to findthe methodto kill the welt.

i -

i :-

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To GetShut ln Drill PipePressure Flct BumpinglProcedures you needto havethe correctfloating ln orderto get the correctvalueof drill pipepressure, bumpingprocedure. ttow to bumpthe float correctly. The Froceduresbelowwill demonstratehow to bump the float correctlyin orderto EietSIDPP. 1- Ensurewell is properlyshut in. No leak or whatever. 2- Recordshut in casingpressure(SICP) 3. Pumpas slowlyas possible(5-10strokeper minute)at constantpumpingspeeddown into and the casin$pressure. the drillpipeand keepmonitoringthe drillpipepressure whilepumping.At thisstage,you needto 4. Youwill seethe drillpipepressureincrease whichwill occurwhenthe float is monitorcarefullyfor a "lull"in the drillpipepressure, showingwhenthe lull is firstseenis yourshutin drillpipe opened.Thedrillpipepressure pressure(SIDPP). to pumpdownthe 5. Youalsoneedto verifythat the float hasbeenopenedby continuing lt shouldhappenveryquickly drillpipeslowlyuntilyouseean increasein the casingpressure. afterthe lullwasseenon the drillpipegauge. is detected. 6" Shutdownthe pumpingoperationas soonas increasein casingpressure you may 7. Checkthe shut-incasingpressureagain.lf thereis any excesscasingpressure, untilit equatesor a littlebit aboveSCPin steps in smallincrements bledoffsomepressure no2. tf youseetrappedpressureon drill pipeafter bumpingthe float, you can calculatethe actual with thisfollowingformula. shutin drillpipepressure Shut in drill pipe pressure= shut in drill pipepressureafter bumpingthe float - Shut in casingpressureincreasewhilebumpingfloat

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Ghapter5: Klck& ShutJnPrccedures

1 ,)a tJ

Shut-lnProcedurewhileTriooing Trippingout of the holeis a criticaloperation, whichdrillingteam must keepcloseeyeon well controlsituationthat canoccuranytime.Wellboremonitoring and holefillingequipmentand mustbe workingproperlyso that the kick can be quicklydetected. Youmust be awareof and prepared for the well controlsituationeverytrippingoperation. Whiletripping,it cancauseswabbingeffectthat mayallowformationfluidenteringinto wellbore.Thewell may not startto flow sincethe swabbingeffectis just started.The pressure. swabbingeffectwill resultin reducingthe overallhydrostatic lf the well is pressure continually swabbed-in in the wellborelessthanformation untilthe hydrostatic pressure, the wellwill startflowing.Anytime that youseeshortfill whiletrippingout,you needto go backto bottomandcirculatebottomup to confirmwellborecondition. -

Whenthe well controlsituationis happenedduringtrippingoperation, the drillingcrewmust shutthe well in rightawayusingthe following"3 S" shut-inprocedures. that mustbe in an openpositionin drill StabValve:InstallFull-Open SafetyValve(FOSV)

-

string.Makeup to drillingstringand closethe safetyvalve.

-

SpaceOut Spaceout to ensurethat tooljointmustnot locatein BOPelement.

-

or uppermostpiperams.Openthe upperchokeline Shut{nwell:Closethe annularpreventer

-

valveagainsta fullyclosedmanifoldvalveat a chokemanifold.Lineup to trip tank to confirm that the well is shut-inandflow hasbeenstopped.

,F

-

PostShut-lnProceduresWhileTripping- What data shouldbe recorded?

-

Afteryoucompleteshutin procedure whiletripping,.there is followinginformation that must

-

be recordedbeforemakinganydecisionon howto kill the well.

-

Readand recordthe shut-incasingpressure(casinggauge). Shut-lnCasingPressure(SIGP):

lr

In orderto get the properpressure reading,the casinggaugeshouldbe installedupstreamof

l-

the closedchoke.

-

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Pit Gain:Readand recordthe pit gain.Pit volumegainedis verycriticalfor the maximum casingpressure calculation. Practically, whiletrippingout of hole,a trip tank is usedto trackdisplacevolumein use.The accuratepit gainvaluecan be easilyfigureout byfindingdifferencebetweenactualvolume

tt Lt Lt tt Lt Lt Lt Lt Lt

if the activepitsare usedto takento fill up wellboreandtheoreticalfillup volume.However, recordthe displacement volume,it will be verydifficultto figureout the accuratepit gain.The the pit gainis the sameas usingthe trip tank. However, the reason conceptof determining hat I saythat it is verydifficultto get the accuratepit gainbecausepit volumeis too largeto recordfew changeswhiletripping. Time:Recordthe time that the well controlsituationis occurredand keepan accuratetime logfor the entirewell kill operation ElitDepth:Recordbit depth.

t{

tt tt tt tt tt tt Lt

Shut{n while WlrelineLoggingOperation whilewirelineloggingoperationareverycriticalfor all drilllingcrew Shut-inprocedures workingon the rlg.Let'slearnabouttwo vitalcasesof the shut-inprocedures.

Lt tt

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Chapter5: Kick& Shut-inPrccedures

,-J

wlre lineare as follows: Twocasesof shut the well in while lo€lElin€lwith 1. Shutthe well in whilewirelineloggingthroughopenBOPwithouta lubricator. 2. Shutthe well in whilewirelineloggingthroughopenBOPwith a lubricatorinstalledin the BOP. Firstcase:Shutthe well in whilewirelineloggingthroughopenBOPwithouta lubricator. Firststep:Stop loggingoperation

-

Secondstep:Shutthe well in byfollowingtheseprocedures; becausewe wouldliketo usethe annularpreventor elementto 1. Closeannularpreventor closingpressurein orderto have squeezearoundthe wireline.Youmay needto increase affectivesealingabilityif necessary. 2. Opena HCRvalveagainsta fullyclosedchokemanifoldvalve. 3. Usea trip tank to confirmthat flow is stoppedandthe well is totallyshut-in. 4. lnformdrillingsupervisors you Thewellsometimescannotbe totallyshut in via a closedannularpreventor therefore m u s tc o n s i d ecu r tti n gth ew i re l i n eand lettingit dr opthenusingblindr am sto shutthe w el li n andthe instead.lf the annularpreventor couldnot sealaroundthe wirelineeffectively (BOP), youmayconsider wirelinecannotbe cut and droppedthroughthe BlowOutPreventor usingshearramsto cut the wireas the lastoption. Secondcase:Shutthe well in whilewirelineloggingthroughopenBOPwith a lubricator installedin the BOP.

-

Firststep:Stop loggingoperation Secondstep:Shutthe well in by followingtheseprocedures;

-

packoff sealsat the lubricator. Youmay needto increaseclosingpressure in 1. Energize orderto haveaffectivesealingabilityif necessary.

-

2. Opena HCRvalveagainsta fullyclosedchokemanifoldvalve. 3. Usea trip tank to confirmthat flow is totallystoppedandthe well is properlyshut-in.

-

4. Informdrillingsupervisors

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Shutin while Drillingon FloatingRigS on floatingrigwhiledrilling(withCompensator): shutin procedure Universal

-

1. Stopdrillingand positiontooljointsawayfrom Rams.

-

1 1 1 1

2. Stoppumps. r p perAnnular ) . r OP(p re fe u 3 . C l o seA n n u l aB

-rl,

1 1 1' 1' -t'

4. Openfail safechokelinevalveon BOPwith remotechokeclosed. to permitstrippin$of tooljoints. 5. AdjustAnnularClosingPressure (byusingupperpiperam with motion with hang-offprocedures. 6. Continue compensator) and Pit Gain. 7. RecordShut-lnPressures

rlt 1 rt rt -1' -1, -1, rt

Top of lorver sheu blade.

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Shear Rams

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Hangoff Rams

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WellGontrolManual Ghapter6: Shutin Data

6J.

SHUHN DATA

flDPP

After thekickiscontained, theSIDPP andSICP canbereadatthe ChokeControlPanelordirectly fromthestandpipe gauges. andchokemanifold lt is essential thatthedataberecorded atthetimethewellisshut-in. TheSIDPPandSICP pressures should berecorded initially at1-minute intervals untilthe have lt is stabilized. important to record thedatafrequently inorderthatanychange intherateof buildup canbeclearly identified,

. Usually, therateof buildupis relatively fastuntilthewellbegins to stabilize. Oncethepressures havebeguntostabilize, anyfurther

significant increase inbothSIDPPandSICPmaybeindicative of kickmigration,

b Lr b b

pressure Theshut-in drillpipe reflects thedifference between thekick

tt b tt

pressureof zonepressure andtheeffective hydrostatic themud

!t

drillstring. ltcantherefore beusedtodetermine thekick.formation

Lt ft b !t D b

pressure.

hr

column inthedrillpipe, assuming thattheinfluxhasnotentered the

!t

b b b

p

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Well GontrolManual

PAGE

Ghapter 6: Shut-inData

-1

2of8

---1

INFLUX MIGRATIOI{ CIccuf,Rtt'lG

,-,tJ

-

=s fL

ul t

=

al, m uf

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ANNU[-U5 PRESSIJRE __*__*

-

u,

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FRESSURE I I I I I

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TIMEELAFSED AFTERSHUT.III

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SurfacePressures AfterShut-ln

-

(S|DPP) 6.2 SHUTrNDRTLL PIPEPRESSURE

-

- Hydrostatic SIDPP= FormationPressure Pressure of mudcolumn

-

= Hydrostatic FormationPressure Pressure of mudcolumn+ SIDPP Whenkickentersduringdrilling, the mudin drillstringis notcontaminated, butthe annulus willbecontaminated byinflux.

-

Therefore, is usedfordetermining SIDPP theKillMudWeight: K III Mu d w e i g ht:

Or iginal M W +' ( -

-

SIDPP

x W eIITVD \o.osz

-

or

-

Kill Mud.Weight: FormationPressure+ 0.052 + WeIITVD

-

CopyrightReserved

DrillingWell ControlManual

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WellGontrolManual

PtT

Chapter6: Shut-inData

63

(SICP) SHUTrN CASINGPRESSURE

STDPP

Shut-inCasingPressure(SICP)is the differencebetweenthe (FP)andthe combinedfluid Hydrostatic FormationPressure (HSP)in the annulus(Thispracticeis appliedonlywhen Pressures no Influxmigrationalongthe well aftershut-in) SICP= FP - HSP (ln the annulus) = HSP(allfluidcolumnsin the annulus)+ SICP FormationPressure SICPis usedfor determiningthe InfluxGradientor InfluxType

Example: WellTVD: MW: SIDPP: Heightof gasinflux: Gasdensity:

10000ft 10.2ppg 620psi 900ft 0.1 psi/ft

l l

theBHPandSICP? Calculate fromDP Side: Calculation = ( 1 0 . 2x 0 . 0 5 2 x1 0 0 0 0+) 6 2 0 BHP = 5924psi fromAnnulusSide: Calculation SICP = BHP- MudHSP- GasHSP = 5924- (10.2x 0.052x 9100)- (0.1x 900) = 5924-4827-90 = 1007psi

0_1 ilfi

I FP = BHP

4

i

( /b /

Well ControlManual PAGE

Ghapter 6: Shut{nData

4 of8

/: ( /\ ( ( t\ -

1. Usuallybeforea kickis detected, therewill be: a) b) ,c) d)

ra :

Nowarning An increase in pumppressure in mudflow,mudvolumeanda decrease An increase in pumppressure Reduced drillingrates

ra b € -

r €

2. Fora Softshutin, the chokemanifoldshouldbe linedup with:

F

r a) b) c) d)

well controlpolicyspecifies Whateverthe contractor's valveclosedandall linesopenthroughmanualchoke Hydraulic chokeclosedto MGS Hydraulic valveopenandhydraulic chokeandlinesopento MGS Hydraulic valveclosed,hydraulic

-

F C F -

3. Statistically, mostof all blowoutshavebeencausedby:

a F

pressured formations a) Abnormally ,'b) Peoplenot reachingor handling properly situations failures c) BOPequipment d) Lostcirculation

-

F F €

4. Pitalarms,FlowlinealarmsandTriptanksshouldbe usedandmonitored while drilling, trippingor killing. TRUE

F F F

e F F

FALSE

a 5. It is a gooddrillingpractice to keep:

F

e a) b) c) d)

F F

An accurate and up to datepumpoutputfigures raterecorded eachtour A slowcirculating Allcrewstrainedandwellcontrolconscious All of the above

€

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Drilling WellControl Manual

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! E h h h

a

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Chapter6: Shutin Data

a

-

dailyusing: shouldbe recorded information 6. Allwell kill pre-recorded

E Il E

t a

E

Chokecontrolpanel Gaugeson the hydraulic gauge The standpipe The kill manifoldgauge Chokemanifoldgauges

a

to followif total lost 7. WhichTWOof the optionsbeloware the correctprocedures whiledrilling? occurred circulation

E

a) b) c) d)

a a

4 4 4 -

!? -

4 4 4 4 1 1 -

1 1 1 1 t)

a) b) c) d)

Stopdrilling,changefrom mudto saltwaterandcontinuedrilling Stopdrillingandobservelevelin annulus the volumepumped Startfillingthe annuluswith watermonitoring returns no Drillaheadwith a mudcapand

8. Thestepsfor closingin a wellby the Softshutin methodare: a ) Pickup of bottom,shutpumpdown,closeBOP,openchokelinevalve,close choke,and recordpressure b) Shutpumpdown,pickup ofFbottom,openchokelinevalve,closeBOP,close choke,andrecordpressure c) Shutpumpdown,pickup off bottom,closeBOP,openchokelinevalve,close choke,andrecordpressure d) Pickup off bottom,shutpumpdown,openchokelinevalve,closeBOP,close choke,and recordpressure withthe Bit nearthe bottomis usedto calculate: 9, SIDPPrecorded a) b) c) d)

Increasein mudweightto balanceformation.pressure Influxgradient Initialcirculating Pressure All of the above

-, -,

h ,a t't tt tt

DrillingWell ControlManual

WellControlManual Ghapter6: Shutin Data

;) PAGE 6of8

-

2 -)

7 the shoeat 7,000TVD, out.At the timethe gasreaches 10.A gaskickis beingcirculated psi. at the top of bubbleof 5,000 If the originalmudweightis therewasa pressure t2.5 ppg,what wouldthe casingpressureat surfacebe? a) b) c) d)

/

c -

1,000psi 2,000psi 450 psi 600psi

€ € -

11.All kicksshouldbe handledas a gaskick:

-

TRUE

-

FALSE

-

eof usingthe Softshutin procedure? 12,Whatis the mainpurpose

-

a) b) c) d)

-

shockthat mightdamagethe formation Preventa hydraulic Preventmoreinfluxfromenteringthe wellbore procedures To reduceshutin operation All of the above

-

?-

is 13.Thereare a numberof earlysignsthat mayindicatethatformationpressure indicators': these four of List below increasing.

-

a) b) c) ...'.'.;..'.'.'..' d)

-

lessthanthetrip is considerably 14.Whiletrippingin, if the mudwhichbeingdisplaced, then: sheetschedule,

-

a) b) c) d)

to migrate An influxis beginning Losses areoccurring Thewell is flowing pressure the recorded Shutthe wellin andassess

-

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t h

rl ts t

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Well @ntrol ilanual Chaptere ShutinData

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gas"is indicated? when"connection 15.Whichof the followingwouldbe recommended (Twoanswers)

E t E

r-i

a) b) c) d)

Increasethe mudweight Increasethe mudviscositY Controlthe rateof Penetration Increaseweighton Bit

F

-

drillingbreaks? for significant is recommended 16.Whichoneof the followingpractices

r-

r-

a) b) c) d)

Shutin andrecordPressure Stopdrilling,pullbackto shoeandflowcheck Increasepumpspeedandreduceweighton bit StoPdrillingandflowchPck

r-

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whena vertical factorswill affectthe shutin drillpipepressure 17,Whichof the following wellis shutin withthe bit nearbottom?

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a) b) c) d) e)

aroundthe collaror pipe Theannularcapacity TheVolumeof the kickfluid The tYPeof Kickfluid TheformationPressure All of the above

rF

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whena wellis 1g.Whichof the followingfactorswill affectthe shutin casingpressure shutin with the bit nearbottom?

Ir4 -i f-f

-

a) b) c) d) e)

andpipe aroundthe collars Theannularcapacity Thevolumeof the Kickfluid The tYPeof Kickfluid TheformationPressure All of the above

4 -

b t-

were500psion the drillpipe shutin pressures 19.Thewellwasshutin andthe stabilized (SIDPP) and700 psion the casing(SICP),Welldepth12,000ft. TVD/MDandmud this pressure? to balance weightinuse12.4ppg.Whatkill mudis required

L-

Ltt-

t-l-7 '

Answer:

ppg

DrillingWell ControlManual

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Exercise4 Answer

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€

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14. 15. 16. 17. 18. 19.

I I I I I 1 I 1 I 1 1 I 1 1 1

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Chapter7

Well GontrolManual

PTT

Ghapter 7: Behavior of GasInflux

7.I

PAGE

1of31

TYPEOFINFLUX

Influx type can be determinedif we know:

tt tt Lt tt Lt

h tt b h h b

Lt , ,

Lt

v

.

Theamount of PitVolume Gain.

.

Shut-inDrillPipePressure (SIDpp). Shut-in Casing (SICP). Pressure

.

Having closeda wellaftera kick,stabilized pressures arereadandrecorded andthe volumeof influxis calculated fromtheamountof increase in thesurface active system volume. Summaryof Kickfluid weight Lessthan0.156psi/ft(Lessthan3 ppg)

= Gas

0.156to 0.468psi/ft(from3 to 9 ppg) .Between

= Mixture of gas,water,oil

Between 0.468to 0.520psi/ft(from9 to 10ppg)

= Saltwater

7 . 2 GASINFLUXBEHAVIOR IN OPENWELL Theeffectsof gasmigration in openwell(uncontrolled expansion) are: Reduction in BottomHolePressure. Gasbubblepressure reduces.

t

Pressure belowthebubblereduces.

> Lt

Pressure abovethe bubbleremains constant.

Lt Lt Lt tt Lt

Boyle'sGasLaw and lts Applicationin Drilling

l" Lt t= L:

Boyle'slaw statesthat at constanttemperature, the absolutepressureandthe volume of a gas are inverselyproportional withina closedsystem.

UnderstandBoyle'sLaw

l-

! !l-. L '

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C ( /\ (

Well ControlManual PAGE

7: Behavior Ghapter of GasInflux

2ot3L

/\ /\ /\ lf

C ( o

la

3

1-

E

C ll-

PreesursP -

aboveusingsimplemathematics Wecandescribe asfollows: thestatement

lfl

-

Boyle'sLaw:P xV - constant,that is,

-

andV - Volume PLxYL- P,xY2, WhereP - Pressure

l-

Let'sapplyBoyle'slaw intoourdrillin{business

-

pressure, 14.7psifor atmospheric when1 Calculate thevolumeof gason thesurface, witha formationpressure outfromreservoir of 3,000psi. bblof gaskickis circulated

-

r -

Boyfe's GasLaw:P1 x V1 = P2 xY2

C -

P1= 3000 psi (reservoirpressure)

-

r

Vl= 1 bbl(volumeat bottomhole)

-

pressure) P2= L4.7 psi(atmosphere

-

r

Y2 = ? (volumeat surface); UsingP1x V1 = P2xY2

-

3000 xi-= L4.7 xY2:

Y2=(300Ox1)+(1,4.7)

C la

Y2 = 2 O 4 b b l o

lJ

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OrillinsWell ControlManual

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h

PAGE

Chapter 7: Behavior of GasInflux

a

3 of31

I

rf I

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-q

t

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0fr

a

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tt

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7.5(x)tt

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H -t

-, -]

BHP decreasebecauseheight of inllux is changed H -

7.3

E ts

GASINFLUXBEHAVIORIN CLOSED WELL

If gasis allowedto migratein the wellborethat is closed-in, therewill be no roomfor expansion. Gaswill carryits originalpressureas it movesup.

ts ts

Therefore, the effectsof gasmigrationin closedwell are:

4 r{

.

Gasinfluxpressure remains the same.

.

SIDPP & SICPwill increase.

.

Bottomholepressure will increase.

.

Pressure at anypointbelowor abovethe influxwill increase, and

F -l F E

BHP,SIDPP & SICPwill all increase by the sameamount.

El Et El Et -l El E E lq

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Drilline W e l lC o n t r oM l anual

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Well GontrolManual of GasInflux 7: Behavior Ghapter

PAGE

4ot3L

-

,a ,tJ

/

Case1: Gas Influx behavior in closedwell

,a ,J

0 Psl Swfaco Pre3srm

t300 Psl

3gmPsl

2flD PSI

5400Psl

/ / /

0 n

tf

2,500n

( ,a

5,000n

-

7,500fi

: F

t0,000fi 9100Psl

r{t400P$

: : -

Case2: GasInflux Behaviorin ClosedWell (Pressurein ClosedWell when is constant andthegas thetemperature GasSwabin & migration):Assume withregard allthewayto thesurface volumeandpressure wouldretainitsoriginal to GasLaw. 3t6o pd

oPd

C C -

C -

t600 pll

-

a Assu

wouldr

the re is its

b F€s$ureall6e wilh thesu regardtoGas Lm {sm|tl

$to t*l

tilh

SICP={l ThereforeBlFedlfi

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Well GontrolManual 7: Behavior of Gaslnflux Ghapter

PAGE

5 of31

Case2: GasInflux Behaviorin ClosedWell

,

oI o

Tlme Change in SICP bulld rate resulting from gas mlgratlon from one hole or annulus slze Into another

pressure bythe formation in surface aftershutin wellis alsocaused ilote: Rising permeability permeability, zonetheinfluxwillcomein slowly. in low especially

FILE:II{FLUX-2

FILE:KICK-1

Anlncre in SID & Sl0Pwith samgamount

IiR$XTT

BOTTOI| ltor.E Influratbotbmoralong Annulusbetween DC/OpenHole

Influxmovinfupwadalont Annulus between DP/ OpenHole

-

Well GontrolManual PAGE

of Gaslnflux 7: Behavior Ghapter

6 of31

-

PercolationRate (Gas Migration Rate)

-

Rate The Percolation In the close-inwell situation,gaswill travelup the annulus. by: Formula#18 canbe calculated GasMigration Rate(ft/hr) =

The inf lux tni.grated(ft) =

Increase in DP pressure (psi/hr)

Mw(ppg) x 0.052

-

Increase in DP pressure(pst) Mw( ppg) x 0.052

Note: gasmigration wellunless ratein a horizontal Donotusethisformulato determine section. thegasmovesup in thevertical

/-

Example1: Duringthe hadbeenrecorded. Wellwasshut-indueto kickandshutin pressures pressure andSICP SIDPP that on both is recorded it monitoring of next30 minutes = mudweight 10ppgandwelldepthis by 250psi.If the present hasincreased 8,500'TVD.

-

in feetper hour. the rateof Influxmigration Calculate

-

perhour = in pressure Increase Rateof Influxmigration(ftlhr) : =

250x2

= 500psi

500 10 x 00,,

-

-

961.5ftlhr.

-

Note: the distanceof in psi,simplycalculate increase If datagivenis onlytotal pressure migrationin feet by usingthe sameformula. The inf lux migrated(f t) -

Increase in DP pressure(psi) M w( ppg) x 0.052

-

,1

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Well ControlManual

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7: Behavior Chapter of GasInflux

b tt b h -

-t -

rt -t x x

7 olSL

Volume of mud to be bled-off: constantduringgas Thevolumeof mudto be bled-offto keepBottomHolePressure rnrigration is givenby: Fomula#26 Volumeto be bled of f (bbl) = l'i.lume to bleed of f =

14

Increasein DP pressure(psi)x Pit Gain (bbl) Formationpressure- Increasetn DP pressure

Increase inpressure(psi) x Capacity of hole above bubble (bbl/f t)

Mud Increment(bbl)

Mud gradient

:

P r e s sur e I ncr ement (ps i) x Annul ar Cap ac ity (b h I / f t)

4 -

PAGE

0.052 x Mw(ppg)

STRIPPINGPIPE

4 H Shut in with AmularBOP

bt

ts r.t 1 rt -,

rt F

rt Stripping Pipe into Hole (shut in while bit off bottom)

-,

rt -t

When shut in well wath bit far off bottom and gas influx is on bottom

r{

of the well:

14

.

Formation Pressure. to determine SIDPPis not applicable

-! rt

.

Pressure if influxis at the SICPwill be usedto determineFormation bottomof the holeandthereis no migrationupward.

.

Whilestrippingpipebackon bottom,the mudshouldbe bled-off equivalent to the closedend displacement of drill pipeat regularintervals constant. in orderto maintainBottomHolePressure

|{ Hl

-:

(

C (

Well ControlManual PAGE

7: Behavior of GasInflux Ghapter

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8of 31

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Case3: Gas Influx Behavior in Killing Well I' P{T

28 Psl

195 PSI

Crtecc _ h'!qm

(

0fi

-

2,500i

-

C

5,m t

(

7.5mn

-

e

ro.m i 80efi1fi FIIAIN

5m P$

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ffi

Plll

F -

t PIB _ offi||d C..eftba

t H wn w

l

-t-

l

rc

Brrll 6*l

8ild

G*r

n

8ild Gdl

eF -

Whencirculateup the annulus: . .

-

headof of hydrostatic dueto decreasing Thepressure of influxreduces fluidaboveit.

F

is maintained constant, sothecasing Sincethe BottomHolePressure pressure for thelossof mudhydrostatic. willincrease to compensate

F

.

pressure whenthe at anypointin th6wellborereaches Themaximum point. Influx is that top of at

.

pressure whenthetopof the at thecasingshoereaches Themaximum influxis at theshoe.

-

-

r -

F

e. F F F F -

F -

F

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Well GontrolManual of Gaslnflux Chapter7: Behavior

PAGE

9 of31

Case-3:GasInfluxBehaviorinKillingWell The pressureof Influxreduces dueto decreasinghydrostatichead of fluid aboveit.

C.ilh|ts|t

of the driller's and pit volumedoin{ durinAthe firstcirculation Howare pressure method?

will of driller'smethod,the casingpressure Whenwe performthe firstcirculation will be observed and the maximumcasingpressure increasedueto gasexpansion whenthe gas influxreachessurface. the gaswill expanddueto pressure Whengasis movedupwardduringcirculation, decrease(referto Boyle'sEaslaw P1V1= P2Y2).Thehighergas is movedup inside the systemhydrostaticpressurewill be annulus,the higherexpansionwill be.Therefore, will increasein orderto maintain Forthis reason,the casin$pressure decreased. constantbottomhole pressure.

Reserved , Copyright !4

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DrillingWellControlManual

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Well ControlManual 7: Behavior of GasInflux Ghapter

( PAGE

10of31

-

Letstake a lookat the equation

-

Bottomholepressureconstant= CasingPressure(increaseto compensatefor loss Pressure(decreasedue to gas expansion). hydrostaticpressure)+ Hydrostatic

lr -

will Whenthe gasin the mud startscomingout on surface,the casingpressure lf the gaskick in the annulusis totallyout of hole,casingpressure decrease. continually (SIDPP). In addition,pit volumewill shouldbe equalto Shut{nDrillpipePressure

-

Whengas reachessurface,the increaseuntil gas reachessurfacedue to gasexpansion.

-

-

-

pit volumewill startto decrease.

-

The plot belowdemonstratespressureprofileof bothcasingpressureand tubing pressure of driller'smethod. during1st circulation

-

PrG$ura ProfiL - 15t Circulation ot DrilLr Melhod

-

2 000

A

1,800

r 600

/

-

/ I

1 400 o (l

r.200

o 5

roco

6 e o i

-

800

-

600

/ 100

-

0 0

100

200

300

a00

500

600

700

400

900

100n

1100

1200

-

StokcsPumP€d

-

profileof 1st circulation of driller'smethod Pressure

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Well ControlManual PAGE

7: Behavior of GasInflux Ghapter

11of31

OFGASI I{FLI'X BEHAI,|OR Whib

CiEohlhgflt

of dtc WGt

tt

? ? ? ? t t

Pilgdn ' Inll|l lrolun

4' 1 1'

a 1 a, a, 1

Ursllinitirl Shutin Conditon B H P =F P

Nomrl DrilliDg BHP> FP (ovcrb!lrnc.)

4t 1' 1' 1' 4'

a

LXomefPit

4'

t t

larcl

11' 4'

1

+

,

t 1 14'

a a ,

,r!,

2 ?

?

KilliqgEll

-l(epBHP

The marirnum pressure@ anypointin thewellbore reaches whenthetop of lnflqis at that point

It

)I

t|x- Shoa Prra$rc

.The maximurn pressure@ thecasfrg shoe reac{res when top of Influxis attheshoe

)

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Well GontrolManual PAGE

7: Behavior Chapter of GasInflux

-..i

L12ot3t -

BEHAU(nOFGASINFLIIX Whlb

Chob|frgoEt

-

of th6 Wel

-

Xilling *cll . Xccp BHP condalt

W

Caing (Chok6)PHurc 0rcorlo " SIDPP lilwbcondddy rEilowd lrom uell

lnnuxpsing h.oughChohc Pit levelir dropf,ing llom.lPil lltrl

ghs PaHure condsnt

ShoaPHUG

can3trni

4 J l

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I

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=' Killi|rgUGll -fiGcp BHPcd|.tnt

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Well ControlManual Ghapter 7: Behavior of GasInflux

PAGE 13 of 31

LI

L!

All RghBResen

E E}I'MOR

OF GAS I I{ FLI'X

WrileCfcda

odotthawdl

ed

I

br I

b{

t!-

h L-

llstill under balance by slDPP

L F ShoaFI.

E

aUG conrLnt

-t -t rE Fl

Wcll Shut in condilion BHP - FP* [HgP+ BtOpPl

ts lH

-! rE

7,4

-t

1. GasInfluxHighlycompressible.

BEHAVIOROF DIFFERENT TYPESOF INFLUX

.

ts

If not allowedto expand,gaswill bringformationpressure to top and createexcesspressure in the wellbore.

El El

ts

2. OilInflux .

Similarbehavior as gasbut lesscompressible.

El

ts

rn

3. SaltWaterInflux Wateris incompressible.

El El

ts El E

-

Mostlywaterinfluxcontainssomegasso surfacepressurehasthe same patternas seenduringa gaskickbut to a lesserdegree. It is recommended that everykickshouldbe handledas Gaskick. (to understand behavior of Gasin the wellof all situations)

aJ

-

t'-,./ )

Well GontrolManual 7: Behavior of GasInflux Chapter

PAGE

L4ot3L

.J tJ -J

-

GASKICKIN OIL BASEDMUD (OBM) :

-1

in OBMor stayin If gaskickin wellwhendrillingin OBM,somelightgaswilldissolve solutionuntilit hasreachedthe bubblepoint.

,-a

The effectsof gaskickin OBMare as follows:

,1 1

mud(WBM),thus 1. Kicksizeis lessin the OBMwell,compareto water-based verydifficultto detectgaskickin OBMthanin WBM.

-

willbelowerin OBMthanin WBM. Pressure 2 . Shut-inCasing -

HSPof mudmorein WBMthanin OBM. 3 . Gaswillreduce

-

to gasupthewell,thegaswillexpand lessin OBMcompare 4. Whilecirculating its bubblepointthengaswillexpand gaskickin WBM,untilthegasreaches at nearsuface. more(exponentially)

-

will be lessin gasup the well,surfacepit-gainmeasurement 5. Whilecirculating OBMthanthat in WBM.

-

ts ,,fl

,1

,1 ,1

,,?1

2-

tr ieht Reserved

l anual DrillinW e e l lC o n t r oM

PTTCOLtd.

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Well ControlManual Chapter7: Behavlor of GasInflux

PAGE

15of 31

1. well wasshutin with SIDPP= 500psi,sICP= 700 psi,MW= t2.4 ppg.TheInflux vofume= 11 barrelsandit is arounddrillcollars(DC/OHcapacity= 0.0292bbl/ft). If aftera few minutesfrom shuttingthe well in, bothshut in pressures had increasedby 225 psi.Howfar hasthe bottomof the influxmigrated? Answer:

ft.

2. Whichoneof the followingdoesnot increase with gasmigrationin a shutin well? a . Bottomholepressure b. Casingshoepressure Gasbubblepressure d . SIDPP e. SICP

e

Givendataas follows,answerthe questions3 and4: Wellwasshutin whileout of the hole(no drillstringin the well).A stabilized shutin rasingpressurewas recorded.Sometimes later,the SICPhasrisenby 100psi. = 15.4pp9

I'|w

9-518"CasingCapacity = 0.07323bblsift

b b b b b b b b b b b b I b

3. Howfar hasthe kickmigrated? a b c d

150ft. 125ft. 100ft 185ft.

4. HowmuchMudshouldbe bledoff at the chokein orderto reducethe surface pressureby 100psi? a) b c d

9.14bbls 12.4bbls 10.94bbls 7.53bbls

b b b

t

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Well GontrolManual 7: Behavior of GasInflux Ghapter

PAGE 16of 31

-

gaugereads800psi.Thedrill 5. A well hasbeenshutin on a kick.Thecasingpressure gaugereads200psi.Thereis a floatin the drillstringabovethe bit. How pipepressure wouldyou obtaina SIDPP?

-

a Performleakoft test on the drill pipe gaugeflicks.Use b Pumpslowlydownthe drillpipeuntilthe casingpressure pressure on the drillpipegaugeas the SIDPP the corresponding usingthe SICPand pit gain.Subtract the the bottomholepressure c Calculate pipe get to SIDPP hydrostatic headof mudin the drill d All of the abovecouldbe used

-

6. Wellhadbeendrilledaheadat 5 feet/hr.for severalhours.Thewellthenkicked were:Aftershuttingin the pressures whilemakinga connection. = = SIDPP 200psi,SICP 50 psi Therewas a very heavyflow from the drill pipewhendrillcrewsweretryingto make problem,whichoneof on the holecleaning up the Kelly.If therewasno indication causeof the highSIDPP? the followingis possible

-

a b c d

-

The influxis migrating Thedrillcollar/annulus spaceis verysmall The influxhasenteredthe drillstring Thereis a lightslugin the annulus

14

F 4

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Well ControlManual

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PAGE

7: Behavior Ghapter of GasInflux

L7 ot3L

the SICPwhenthiswellwasshutin. 7. Fromdiagrambelow,calculate SIDPP

Holesize = 8-L12" Welldepth = 10,400ft. TVD DrillCollarlength= 720ft. DP/Open holecapacity= 0.0452bb||ft DC/Open holecapacity= 0.0292bbllft

SIDPP= 540psi PitGain = 25 bbls

Mudweight = 11.6ppg l* *r

r

Influxgradient= 0.107psi/ft

' l

I t l*ri ll r | * l

Whatis the approximate shutin Casing pressure?

a) b) c) d)

Reserved

850psi 941 psi 1,035psi 785psi

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Well ControlManual

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Ghapter7: Behavior of GasInflux

18of 31

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I ( -

Given data as follows, answer the questions 29 and 30:

-

Welldepth

10,000ft. TVD

-

9-518CasingShoe

7,500ft. TVD

-

8-t12"HoleCapacity

0.0702bbt/ft

-

CasingCapacity

0.07s8bbt/ft

MudWeightin use

1o ppg

-

6-112"DrillCollar800ft.

-

DrillCollarCapacity

0.007sbbl/ft

-

DrillCollarMetalDisplacement

0.0330bbr/ft

-

5" DrillPipeCapacity

0.0t776bbl/ft

-

5" DrillPipeMetalDisplacement

0.007sbbr/ft

-

DC/Open holeCapacity

0.0292bbl/ft

DP/Open holeCapacity

0.04s9bbt/ft

DP/Casing Capacity

0.0s0sbbl/ft

-

t( -

Whiletrippingout of the holethe wellkicksandthe diillershutin the wellby Annular BOP.Bitdepthat that timeis 9,000ft.

SICP=200psi,

Influxsize =10 bbls,

Gradient of Influx

=0.12psi/ft

8. Calculate the volumeof Mudto bleedoff for everyfoot of pipestripedin the hole.

bbr/ft

9. Calculate the totalvolumeto bleedoff whilestrippingto bottom. Answer

CoovriehtReserved

-

F F

XASSUME INFLUX IS ONBOTTOM ANDIS NOTMIGMTINGX

Answer

-

bbls

Drilline WellControlManual

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Chapter7: Behavlord Gre Influx

PAGE

19 oil31

se 5 Answer 1. 2 3 4 5 6 7 8. 9.

349 ft. . c . b . a . b . c . b 0.02s3bbl/ft 25.3bbls

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Well GontrolManual PAGE

Ghapter7: Behavior of Gaslnflux

20 of31

Stack] KillSheetExercise-3 [Surface'BOP Well Data Holesize Holedepth Casingshoe,13-3/8"

t2-t14" 6,600ft. (TVD),7,846ft. (MD) 4,800ft. (TVD),5,180ft. (MD)

Capacities Drillpipe,5" Drillcollars,8"x3"

0.0177bbl/ft 0,0087bblift

AnnulusCapacitiesbetween:Drillcollarsin openhole Drillpipein openhole Drillpipein casing

Length530ft. -

0.0836bbl/ft 0.1215bbl/ft 0.1353bbl/ft

Mud pump data efficiency0.119bbl/stroke Displacement at 98%volumetric Slow pump rate data 440 psi

@30spm

J

Formation leak off test data A Leak-offtestwascarriedout at the 13-3/8"casingshoe,usinga muddensityof 10.6ppg. of 1,000psiwasrecorded. A surfacepressure Kick Data Thewellkickedat 6,600ft. (TVD),7,846ft. (MD) SIDPP

=

340psi

SICP

=

410psi

Pitgain

=

12 bbls

MuddensitY =

J

11.4PPg

The well will be killed using the Wait and Weight method at 30 SPM

CopvriehtReserved

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OrillineWell ControlManual

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\i Well GontrolManual PAGE

Ghapter7: Behavlor of GasInflux

2Lst3L

(IESTIONS:-

1. Whatis the killmuddensity?

2. Howmanystrokesare requiredto pumpkill mudfrom surfaceto the Bit?

3. Howmanystrokesare requiredto pumpfrom the Bit to Casingshoe?

4. Whatis the totalannularvolume?

at the timethe wellwasshutin? 5. Whatis the MAASP

(ICP)? Pressure 6. Whatis the InitialCirculating

whenkill mudis ai tne Bit(FCP)? Pressure 7. Whatis the FinalCirculating

the kill mud? aftercirculating 8. Whatis the MAASP

per 100strokesas kill mudis being reduction 9. Whatis the drillpipepressure pumpedto the Bit?

Reserved

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Well Contrcl ilanual

T

7: Belmilord GG Influ Ghapter

PAGE 2f2st3L

KillSheetExercise-3 BOPStack]Answer [Surface t2.4 ppg 1127strokes 2553strokes 1000.67 bbls 800.3psi 780psi 479psi 549psi 27 psilL00strokes

Copyright Reserved

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Well Contrcl tlanual d GasInflux Ghapter7: Behanlor

WE1I DATA: llole size Flde depth l?318' Casingshoedepth

t2-114" 10,040ft. TVD(10,300ft. MD) 7,580ft. TVD(7,740ft. MD)

InHnal Capacities: 5't)rill Pipe 5'l-[wDP, 490 ft. trDrill Collar,575ft.

0.0178bbl/ft. 0.0088 bbl/ft. o.oo87 bbl/ft.

Annular Capacities between; DC/OH DP&HWDP/OH DP&HWDP/Casing llud tump Output DrillingMudDensity

0.0836bbuft. 0.121sbbl/ft. 0.1292bbl/ft. 0.120bbl/stroke 11.5ppg.

PAGE 23of 31

Slow Pump Rate Data; 500 psi @30 sPM Forrnation Strength Test Data; Lrrface LOTPressurewith MW 10.8ppg

2,050psi

lGd< Data; The well kickedat 10,040ft. (TVD) 600 psi SIDPP 700 psi SICP Pit Gain(kicksize) 19 bbls The Wellwill be killedusingWait& WeightMethodat 30 SPM THE ANDANSWER THEKILLSHEETCALCUIATION USINGTHEABOVEDATA,COMPLETE NUMBER 1- 10. QUESIONS

t Reserved

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Well ControlManual

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PAGE

Ghapter7: Behavior of GasInflux

24of31

€ € ( € (

QUESTIONS:

( -

1. Whatis the Killmuddensity?

-

2. Howmanystrokesare requiredto pumpkill mudfromsurfaceto the Bit?

€

C

3. Howmanystrokesare requiredto pumpfromthe Bitto Casingshoe?

€ €

4. Howmanybarrelsof totalvolumein Annulus?

€

e

5. Whatis the MAASP afterwellshutin (initialMAASP)?

€ -

(ICP)? Pressure 6. Whatis the InitialCirculating

-

e (FCP) Pressure 7. Whatis the FinalCirculating

F €

dropper 100strokeas kill mudbeingpumpedto the Whatis the drillpipepressure bit.

€ (

e e

9. Whatis the Maximum mudweightfor thiswell?

€

F of the Killmud? 10.Whatis the MAASP aftercirculation

€ €

11.Doesthe Kickalwaysoccurin the eventof totallossof circulation?

12.Namethe conditions in a wellwhichincrease the riskof reaching the MAASP duringa wellKilloperation?

F F F F ( € € € (

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Well Controltlanual PAGE

Ghapter7: Behavlor of GasInflux

25of 31

Kill SheetExercise-4[SurfaceBOPStack] Answer 1.

L 2 . 6 4 - t 2 . 7p p g

2.

L447.42strokes

3.

24t0.42strokes

4.

1289.25 bbls

5.

7773-L774psi

5.

1100psi

7.

552psi

8.

38 psi

9.

15.0ppg

10.

1300psi

LL.

No,it dependson the mudlevelin annulusandthe Formaon pressure

12.

pressure Longopenholeseco n, largeKicksize,lowformao n breakdown

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Well ControlManual

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PAGE

Chapter 7: Behavior of GasInflux

-

26 of 31

-

Kill SheetExercise-3[SubseaBOPStack] WELLDATA: Holesize Holedepth(Ref.from RKB) L3-318" Casingshoedepth(Ref.from RKB) SeaWaterdepth(MSLto Seabed) Air Gap(RKBto MSL) Internal Capacities: 5" DrillPipe 5" HWDP,690ft. 8" DrillCollar,820ft. 3" ID, ChokeLine,665ft. MarineRiser,650ft. 5" DrillPipeClosedendDisplacement Activesufacemudvolume

-

L2-L14" 9,580ft. (MD),9,020ft. (TVD) 5,180ft. (MD),4,800ft. (TVD) 570ft. 80 ft.

-

0.0178bbl/ft. 0.0088bbl/ft. 0.0077bbl/ft. 0.0087bbl/ft. 0.3892bbl/ft. 0.0254bbl/ft. 230bbls,

11 l,-

lr14

Annular Capacitiesbetween; DC/ OH DP& HWDP/ OH DP& HWDP/ Casing DP/ MarineRiser

0.0836bbl/ft. 0.1202bbt/ft. 0.t242 bbl/ft. 0.3638bbl/ft.

MudPumpOutput(980/o) Drilling MudDensity Seawaterdensity

0.12bbl/stroke 10.5ppg. 8.6 ppg.

Slow Pump Rate Datai @ 45 SPM throughthe Riser @ 45 SPM throughthe Chokeline Formation Strength Test Data; SurfaceLeak-off with 10.0ppgmud testpressure

lrl l1r-

?J

ei 11 ri ?4

690psi 830psi

?1 -

= 1,080psi

Kick Data; Thewellkickedat 9,580ft. (MD),9,020ft. (TVD) SIDPP 475 psi SICP 620psi PitGain(kicksize) 20 bbls

OrillineWell ControlManual

?1 -

l

-

I

4 4 tt-

USINGTHEABOVEDATA,COMPLETE THE KILLSHEETCALCULATION ANDANSWER THE NUMBER 1- 13. QUESTIONS

I

l

l

"/

TheWellwill be killedusingWait& WeightMethod@ 45 SPM

ht Reserved

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P-IT

Well GontrolManual 7: Behavior of GasInflux Ghapter

PAGE

27 otSL

QIJESTIONS: t. Howmanypsi of the pressuresafeWmarqinat the shoein this staticconditionafter wellshutin (beforekilling)? 2. Howmanystrokesare requiredto pumpfrom surfaceto the Bit? 3. Howmanystrokesare requiredto pumpfrom the Bit to casingshoe? fromsurfaceto the Chokemanifold? 4. Howmanyminutesare requiredto circulate the marineriserwith killmudbefore 5. Howmanystrokesare requiredto displace openingBOP? 6. Whatis the killmuddensity,in ppg? (ICP)? Pressure 7. Whatis the InitialCirculating (FCP)? Pressure 8. Whatis the FinalCirculating at killspeed? 9. Whatis the initialdynamiccasingpressure of the killmud(wellfullyfilledwith killmud)? 10.Whatis MMSPaftercirculation dropper 100strokeswhilekill mudis beingpumpedinsidethe 11.Whatis the pressure drillstring? 12.Afterkilling,whatthe newdrillingmudweightis requiredto drillaheadwith riser margin? 13.Whatis the newMMSPafterthe well hasbeenkilled,whiledrillingaheadwith a risermargin?(Chokelineis filledwith thisnewmuddensity).

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Ghapter7: Behavbrd GasInflux

PAGE

28o131

Kill Sheet Exercise-3[SubseaBOPStack] Answer 328-338psi 1,300[+ 50] strokes 4,L571+ 501strokes 227minutes 1,971strokes 1 1 . 5 1 -1 1 . 6p p g 1,165psi 747-777 psi 480psi 533-733 psi 30-32 psi 11.9ppg 559-659 psi

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Well ControlManual

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of GasInflux 7: Behavlor Ghapter

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ra

PAGE

29 of 31

-

-

Kill SheetExercise-4[SubseaBOPStack]

-

WELL DATA:

-

Holesize Holedepth 9-518"Casingshoedepth

8-L12" 11,8s0 ft. (MDTTVD) 8,880ft. (MD/TVD)

Internal Capacities: 5" DrillPipe 5" HWDP,837ft. 6-Ll2"DrillCollar,1,116ft. 2-tl2" ID, ChokeLine,553ft. MarineRiser,540ft.

0.0t72 bbr/ft. 0.0088bbr/ft. 0.0077bbr/ft. 0.0061bbr/ft. 0,3892bbr/ft.

Annular Capacitiesbetween; DC/OH DP&HWDP/OH DP&HWDP/Casing DP/ MarineRiser

0.0292 bbr/ft. 0.0447 bbr/ft. 0.0478bbr/ft. 0.3638bbr/ft.

MudPumpOutput

0.12bbl/stroke

DrillingMudDensity

1oppg.

Slow Pump Rate Data; @ 45 SPM throughthe Riser @ 45 SPM throughthe Chokeline

880psi 1,000psi

Formation Strength Test Data; with MW 10 ppg SurfaceLOTPressure

2,100psi

-

2 -

1 1 1 -

1 E E

Kick Data; The well kickedat 11,850ft. (TVD) 580psi SIDPP 870 psi SICP PitGain(kicksize) 15 bbls TheWellwill be killedusingWait& WeightMethod@ 45 SPM THE ANDANSWER THE KILLSHEETCALCUI-ATION USINGTHEABOVEDATA,COMPLETE L- L4. NUMBER QUESIONS

-t -

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-

Well ControlManual

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Ghapter 7: Behavior of Gaslnflux

30 of 31

-

QUESTIONS:

-

1. Calculate the amountof extrapressure that canbe applied,in the staticcondition down. beforethe casingshoebreaks 2. Howmanystrokesare requiredto pumpkillmudfromsufaceto the Bit?

-

3. Howmanystrokesare requiredto pumpfromthe Bitto Casingshoe?

-

the totalwellsystem(Sufaceto Surface)? 4. Howmuchtimeis requiredto circulate

-

the MarineRiserwith Killmudbefore 5. Howmanystrokesare requiredto displace opening the BOP?

-

6. Whatis the Killmuddensity?

-

(ICP)? 7. Whatis the InitialCirculating Pressure

-

(FCP) Pressure 8. Whatis the FinalCirculating

-

CasingPressure at Killpumprate? 9. Whatis the InitialDynamic

-

of the Killmud? 10.Whatis the MAASP aftercirculation

-

11.Doesthe Kickalwaysoccurin the eventof totallossof circulation?

-

12.Whythe Drilleron a FloatingRigneedsto checkthe seawatertidesall the times?

€

in a wellwhichincrease 13.Namethe conditions the riskof reaching the MAASP duringa well Killoperation?

(

14.Namethe conditions on a FloatingRigwhichmayaffectthe accuracy of mudvolume (P\fD readings andmudreturnflow readings?

(

( ( ( ( (

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Well ControlManual PAGE

7: Behavlqof GasInflux Ghapter

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Kll Sheet Exercise-4[SubseaBOPStack] Answer 1.

t,23O psi

2.

1552 strokes

3.

965

strokes

4.

130

minutes

5.

L637 strokes

6.

10.94- 11.0ppg

7.

L46O psi

8.

958

psi

9.

75O

psi

10.

1638- 1565psi

11.

No,it dependson the mudlevelin annulusandthe Formaon pressure

L2.

To knowthe posio n of tooljointsin the BOPstackrelav e to the Rams

13.

pressure Longopenholeseco n, largeKicksize,lowformao n breakdown

L4.

Craneoperao n, RigheaveandRigpitchandroll

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