Technician Equipment D 2015

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MUD PUMP

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MUD PUMP The mud pump is the main component of the circulating system. It is used to pump the mud from the tanks and inject it in the hole through the surface lines and the drill string. The mud flows inside the drill string till the rock bit and raises in the annulus till the tank. In the drilling oilfield industry, 2 types of mud pumps are used :  Triplex Pump : single acting 3 pistons  Duplex Pump : double acting 2 pistons A mud pump is composed on :  Mechanical part : the engine motor provides the power to the pistons.  Hydraulic part : converts the rotative movement to rectilinear movement. 87

MUD PUMPS

Duplex Pump

Triplex Pump

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Mud Pump Hydraulic part

Mechanical part

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Mud Pump Description

Mechanical part

The mechanical part is composed on :  The Skid or Base  The Bull Gear which is an assembly of High Speed axle and Low Speed axle.

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Mechanical part of Mud Pump

HS LS

Skid

Bull Gear 91

View of the Bull Gear

Low Speed Axle

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Hydraulic part of Mud Pump The hydraulic part of a mud pump is composed on :  The body pump  The Liners  The Pistons

 The Cross Head extension  The Rod of the Piston  The Valves  The Seats

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THE LINERS The Liner of a mud pump has a standard cylinder shape. The volume of fluid discharged is called output mud pump. The length of the liner is the stroke of the piston. D is the size (diameter ) of the liner.

D L Stroke 94

DUPLEX PUMP The Duplex Pump has only 2 pistons. The Mud Pump delivers the fluid both during the inward stroke and the outward stroke of the piston. The piston is simultaneously sucking and discharging. The crank is at 120 degrees. The pump can run at a maximum of 150-170 Stroke Per Minute (SPM).

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Output Mud Pump The output of mud pump is also called Capacity or Pump Factor or Pump Rate. It is assumed to take into account a Volumetric Efficiency v .

Measured output volume v  Theoretical output volume v = 90% Duplex Pump v = 95% Triplex Pump 96

Output Duplex Pump Duplex Pump : Double acting

The Piston is moving forward  from left to right (half stroke). It is discharging front of the piston. In the meantime, it is sucking behind the piston.

2

D π L 4 97

Output Duplex Pump Duplex Pump : Double acting

The piston is moving backward  from right to left (half stroke). It is discharging behind the piston. In the meantime, it is sucking front of the piston.

 4

2

2

(D - d )L

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Output Duplex Pump The output pump for 1 piston is

D2   L  ( D2 - d 2 ) L 4 4



4

( 2D 2 - d 2 ) L

The output for 2 pistons : Pump Rate

 2

2

2

( 2D - d ) L 99

Summary Duplex Pump

Pump Rate   v 

 2

2

2

( 2D - d ) L

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TRIPLEX PUMP The Triplex Pump has 3 pistons. The piston produces the fluid volume during half the crank cycle only. The crank is at 90 degrees. The pump can run at a maximum of 70 Stroke Per Minute (SPM).

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Output Triplex Pump Triplex Pump: Single acting The piston is moving backward  from right to left (half stroke). The piston is not discharging. It is only sucking. There is no volume discharged

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Output Triplex Pump

Triplex Pump: Single acting The piston is moving forward  from left to right (half stroke). It is discharging front of the piston. 2

D π L 4

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Output Triplex Pump The Pump Rate Triplex Pump ( 3 pistons ) is 2

D Pump Rate  3   v   L 4

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FIELD UNITS Oilfield Companies use mostly the follwing units : inch, US Gallon , Barrel.

D : Diameter of the Liner (inch) d : diameter of Rod Piston (inch)

L : Length Stroke (inch) The Pump Rate may be expressed in US Gallon Per Stroke or in Barrel Per Stroke. Some companies use Liters Per Stroke.

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Pump Rate Duplex Pump

US Gal/str  0.0068v (2D - d ) L 2

2

GPM  0.0068v (2D - d ) L  SPM 2

2

Bbl/str  0.000162 v (2D - d ) L 2

2

BPM  0.000162 v (2D - d ) L  SPM 2

2

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Pump Rate Triplex Pump

US Gal/str  0.0102 v D L 2

GPM  0.0102 v D L  SPM 2

Bbl/str  0.000243v D L 2

BPM  0.000243v D L  SPM 2

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Input Power The Power given by the constructor is the maximun mechanical power allowed on the axis high speed.

HP  T   T  2 N LB.FT  2  RPM HP  33000 HP : Power or Mechanical Power in HP T : Torque in lb.ft  : Angular velocity in Rad/min

 = 2N

N : Revolution Per Minute RPM 110

Horse Power : Example A diesel engine gives an output torque of 1740 LB.FT at an engine speed of 1200 RPM, what is the output Horse Power?

The angular velocity  is  = 2 N = 2 x 1200 = 7539.8 rad/min

LB. FT  2  RPM HP  33000 1740  7539.8 HP   397.5 33000 111

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Hydraulic Horse Power

HP  Pressure output Flow Rate

PSI  GPM HP  1714 113

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Mechanical Efficiency

Hydraulic Horse Power m  Input Power  m  85%

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EXERSICES MUD PUMPS

1°) A drilling rig is equipped with 2 duplex mud pumps. Stroke length 12" ; Liner 71/4 ; Rod piston diameter 2" Volumetric efficiency 90% While drilling, the flow rate is 925 gal/min Compute the Strokes. 2°) While drilling in 121/4 section, we use a duplex pump equipped as follow : Stroke length 16" ; Liner 8" ; Rod piston diameter 3" with 50 strokes per minute. Volumetric efficiency 90% Determine the flow rate ? We decide to drill with a flow rate 793 gal/min. Compute the strokes. 116

3°) While drilling in 81/2 section, the flow rate is 396 gal/min. The used pump is triplex and acts with 60 strokes per minute. The stroke length is 12’’ Volumetric efficiency 95% Determine the liner diameter. We decide to decrease the flow rate to 317 gal/min. Compute the strokes. 4°) While drilling in 121/4 section, the gauge pressure indicates 1500 psi. Triplex mud pumps are used and equipped as follow : Liner 71/4 ; Length 12" ; Strokes 45 . Volumetric efficiency 95% Determine : The flow rate The hydraulic power

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