1. Origin Of Petroleum.pdf

THE ORIGIN OF PETROLEUM Dr.Ir.Sudjati Rachmat,DEA

59

1

How Long Does It Take to Make Oil?

59

2

How Does Plate Tectonics Contribute to the Creation of Oil? Crust Mantle Outer core Inner core

59

3

Age of the Ocean Floor Asia

North America

Asia

Mid-Ocean Africa

Ridge South America Australia

Antarctica

Old Crust

59

Young Crust

4

Elements of Plate Tectonics CONVERGENT BOUNDARY Plate subduction

DIVERGENT BOUNDARY Mid-ocean ridge

Sea floor spreading Lithosphere Oceanic crust

Volcanism Mountain building Continental crust

Deep-sea trench Litho

sphe

re

Magma rising

Asthenosphere Magma forming

• Earthquake centers 59

5

59

6

59

7

59

8

59

9

Geologic Time Scale - Biostratigraphy Jurassic period

Triassic period

Permian period Pennsylvanian period Mississippian period

245 m.y 146 m.y 208 m.y

290 m.y

363 m.y

1 b.y

65 m.y

510 m.y

57 m.y 570 m.y 35 m.y 23 m.y 5 m.y 0.01 m.y

Holocene epoch

4.6 billion years ago

ERA PERIOD EPOCH 59

Devonian period

323 m.y 409 m.y 439 m.y

Silurian period 2 b.y Evolution of cells with nucleus 3 b.y First fossil cells

4 b.y Oldest rocks dated on Earth 10

4

4.6

150

Mesozoic

100

Cretaceous

Jurassic

200

Triassic

250

Permian

300

Pennsylvanian

Recent

0 Pleistocene 10 20

Pliocene Miocene

30 Oligocene 40

Eocene

Cenozoic Era

3

Tertiary 50

50 60 Paleocene

Mississippian

350 400 450

Paleozoic

1

Millions of years ago

Phanerozoic

2

Quaternary

0

Cryptozoic (Precambrian)

Billions of years ago

0

Epoch

Tertiary period

Era Period

Millions of years ago

Eon

Quaternary period

Geologic Time Chart

Devonian Silurian

Ordovician

500 550 600

Cambrian 59

11

Origin of Petroleum • Inorganic theories – carbides of iron, calcium etc.. When contacted with water – action of hot water on limestone, CaCO3 and gypsum • Organic theories – Animal theories: due to decomposition of marine animals fishes, oysters, other microscopic organisms. – Vegetal theories : due to decomposition of plants - seaweeds Land plants such as those in swamps coal beds oil Microscopic plants – diatoms : Non-fossil organisms planktons oil 59

12

Origin of Petroleum • Likely scenario: scenario oil

=

ancient animal + plants

paraffinic base - vegetal origin asphaltic base - animal origin

Flow of

sedim ents

SEA/FRESH WATER Water prevents rapid oxidation of organic material 59

Plants and animals 13

Petroleum and Fossil Energy • primarily derived from the remains of once living organisms • most deposits formed some 500-200 million years ago • the three major fossil fuels are coal, oil and natural gas • currently consumed at a rate faster than produced • very likely that fossil fuels will be depleted - the question is when? • large resources in tar sands and oil shales

59

14

Genesis of Fossil Fuels • Comprised of the organic (carbon-based) remnants of ancient life • anaerobic bacteria primarily responsible for breaking broke down complex organic remains into hydrocarbon molecules - molecules of carbon and hydrogen • Pressure and heat applied to the sediment within which organic remains are buried, and degrade (crack) the hydrocarbons into an array of molecules of various sizes. that are useful as fuel products Plant remains + bacteria + pressure + temperature + time = hydrocarbons 59

15

Fossil Fuel Types • Coal: carbonized remains of freshwater plants – swamps •Kerogen: precursor to oil & gas, oil shale contains kerogen not oil • Oil: saltwater algae (high in H) • Gas: mostly methane (CH4) and ethane (C2H6)

59

16

thermal cracking

59

17

59

18

The Carbon Cycle

59

19

Marine organic matter is a major precursor for petroleum

59

20

Organic-rich sediments can form wherever life is abundant

algal bloom

nutrients

59

21

Petroleum System A Petroleum System requires timely convergence of certain geologic factors and geologic events. These Include: Seal Reservoir rock Migration Mature source rock

59

22

Generation, Migration, and Trapping of Hydrocarbons Seal

Fault (impermeable)

Oil/water contact (OWC) Seal

Migration route

Hydrocarbon accumulation in the reservoir rock

Seal

Reservoir rock

Top of maturity Source rock 59

23

Petroleum System Elements Anticlinal rTap

Top Seal Rock (Impermeable)

Reservoir Roc

(Porous/Permeable)

Potential Migration Route

Source Rock

(Organic Rich

24803

59

24

Migration of Petroleum • Source rock – mostly shales • Final accumulation of oil – sandstones, limestones, fractured shales Trapped hydrocarbons

Limestone/sandstone secondary

Regional flow of water

primary

shale 10’s – 100’s km 59

25

Primary Migration • Why does the hydrocarbon migrate from the source rock (shale) to the more porous rocks (sandstone) above? CAPILLARITY water Fs Force at the interface between water and solid due to surface tension

oil

Note shape of interface, concave upwards

Note shape of interface, concave downwards

water Fs α 1 / r

Fs

oil

Shales have smaller pore throats than sands. 59 26 Water flows readily into shales and oil out of shales

Primary Migration • Effect of pressure, heat

Volume of liquid expelled = Shrinkage - compressibility of fluid

Folding and chemical action generate heat

fluids expand and move into more porous beds above 59

27

Secondary migration • Fluid movement due to capillary forces, pressure, temperature effects. Migration until cap-rock or seal encountered. primary

• Regional water flows

59

28

Traps Anticlines

Faults

Stratigraphic

59

Salt domes

29

Traps Combination Anticlinal/fault traps

Overlap on beds flanking the basement rock 59

30

Sedimentary Deposition Shore Offshore

SEA LEVEL RECEDING

Flow of

sedim ents

Shoreface

Near shore/Shallow Marine Offshore/Deep Marine

Coarse grain sediments

Coarse grain with clay

Fine grain sediments

Fine grains with clay

SEA LEVEL ADVANCING

59

31

Cross Section Of A Petroleum System (Foreland Basin Example) Geographic Extent of Petroleum System Extent of Play Extent of Prospect/Field O Stratigraphic Extent of Petroleum System

Pod of Active Source Rock

Essential Elements of Petroleum System

O

Overburden Rock Seal Rock Reservoir Rock Source Rock Underburden Rock

Sedimentary Basin Fill

O

Petroleum Reservoir (O) Basement Rock Fold-and-Thrust Belt (arrows indicate relative fault motion) (modified from Magoon and Dow, 1994)

Top Oil Window Top Gas Window 59

32

Clastic Depositional Systems

Co a stal

Plai n

59

33 Modified from Seni and Hentz, 1997

Fan Deposition

Example

Alluvial sedimentation 59

34

Barrier Shoreline Washover fan

Long

Ebb Tide Delta

D shore

Flood Tide Delta

Lagoon

rift

Wind Back-barrier marsh Sea

Shelf Silts

Ba rrie Shoreface r Is la n Sands dF

ac ie

s

59 35 1982) (modified from Blatt, 1982; after Taverner-Smith,

Athabasca Delta, Canada FLUVIAL-DOMINATED DELTA

Distributary

Photo by L. Klatzel-Mudry

59

36

Carbonate Depositional Environments and Systems

59

37

Carbonate Reef System 30 km

S

N

Back Reef (Lagoon)

Open Water

SL

Lime Grainstone

150 m

Reef Forereef

Miliolids

100

Shelf Dense lime mudstone

50

Orbitolina Chalky lime mudstone

Boundstone

Globigerina mudstone

0 59 (modified from Wilson, 1975; after Harris et al, 1968)

38

Geological and Petrophysical Data Used to Define Flow Units Core Lithofacies

Core Pore Plugs Types

Petrophysical Data

Gamma Ray Flow Log Units

Capillary φ vs k Pressure

5 4 3

2

1 59

39

Schematic Reservoir Layering Profile in a Carbonate Reservoir Baffles/barriers SA -97A

Flow unit

SA -251 3150

3200

SA -356 SA -71 SA -344 3150

3100

SA -371

3100

SA -348 3250

SA -346

SA -37

3150

3100 3200 3200

3150 3200

3300

3150

3250

3200

3150

3250 3250 3300

3250

3200

3250

3250

3200 3300 3350

3300

3250

3300 3250

3350

3350

59

40

From Bastian and others

Stratigraphic Hydrocarbon Traps Unconformity

Pinch out

Seal

Oil/Gas

Unconformity

Oil/Gas Water

Channel Pinch Out

Oil/Gas

59

41 (modified from Bjorlykke, 1989)

Sedimentary Basin and Stress Fields Basin Geometries

Fault Types

Rift Related Basin (Extensional Stress) Normal fault

Sedimentary Fill

Foreland Basin (Compressive Stress) Thrust fault Pull-apart Basin (Lateral Stress) Wrench fault 59

42

Structural Features

59

43

Folded Structures

Syncline

Anticline

59

44

Fold Terminology N b

m Li

m Li

b

m Li

b

Anticline Syncline Modified from xxx) 59

Youngest rock Oldest rock 45

Overturned Folds Anticlinal Axis

xis A l na i l c Syn

59

Photograph by XXX

46

Faulting (normal faults)

Example

Kabab Canyon, Utah Photograph by XXX 59

47

Strike Slip Fault (Left Lateral)

Dip Angle

St

rik e

N

Fault Plane 59

48

Methods of Structural Evaluation Structural Map

Structural Cross Section A’

A 1000

A’

SL -1000 -2000 -3000

OIL

0

00 -10

00 -20

00 -30

+ + + + + + + +

O

OIL/Water Contact

A 2000

59 Depth (ft)

Wa I L ter 49

Structural Hydrocarbon Traps - Fault

Oil or Gas

A Sand

Shale Sand A

Fault Water

59

50

Structural Hydrocarbon Traps Gas

Closure

Oil/Gas Contact Oil / Water Contact

Oil

Fold (Anticlinal) Trap

Salt

Salt Diapir

Seal Oil

Dome

59

(modified from Bjorlykke, 1989) 51

Cross-Cutting Relationships K J I H G Angular Unconformity

C E D

Ign

e

ill S s ou

Igneous Dike

F B A

59

52

Types of Unconformities • Disconformity – An unconformity in which the beds above and below are parallel

• Angular Unconformity – An unconformity in which the older bed intersect the younger beds at an angle

• Nonconformity – An unconformity in which younger sedimentary rocks overlie older metamorphic or intrusive igneous rocks 59

53

Faults Normal Fault

Reverse Fault Strike direction

Strike direction

Key bed

H.W.

F.W.

rown Upth

F.W.

own nthr Dow

ult Fa ar p Sc n ow thr wn Do

n ow thr Up

Fault scarp

Dip angle

H.W.

Dip angle Fault plane

Fault plane 59

54

Classification of reservoir rocks • Sedimentary rocks: Source rock: old sedimentary + igneous

Compaction/ Cementation:

Broken down sediments Wind + water + organisms + chemical action Deltas, shore face, valley fills

Sandstones

Sandstones: compacted quartz sands – fragments of rock crystals Limestones: Skeletons of lime-secreting organisms, corals etc.. Diatomaceous shales: Diatoms and other microscopic plants Gypsum/Anhydrides/Limestones: Chemical dissolution of rocks, 59 followed by evaporation and crystallization

55

Classification of rocks • Igneous rocks- Volcanic origin- Some producing gas fields. Gas found in vesicles formed in basalt due to gas flows through molten lava. Igneous rocks generally indicative of proximity to oil/gas reservoir. • Metamorphic rocks – Both igneous and sedimentary rocks that undergo further change due to heat.pressure and chemicals: Quartz Quartzite Quartz schist clay shale slate schist Generally unfavorable for oil and gas accumulations

59

56

Sedimentary Rocks • Conglomerates: Conglomerates Loose aggregate of rounded pebbles – gravels when cemented – conglomerates. Porosity due to differential cementation Oil fields in Pennsylvania, Texas, Oklahoma • Sand, Sandstones: Sandstones Finer sediments – yet noticeable, angular Sands cemented by calcite – sandstones silica – quartzite Porosity due to voids and inter-grain spaces also differential cementation Pools in California, Alberta, Gulf Coast, Texas

59

57

Sedimentary Rocks • Clays, shales: Fine grained particles – aluminous materials, trapped water Deep ocean sediments : Compaction yields shales Porosity in cracks and fissures Some pools in Santa Maria Basin, California, Gas in Kentucky • Limestone: Principally CaCO3, hard and crystalline rock, Marl, chalk, dolomites – other forms Porosity due to weathering and solution – vugs Many pools in mid-continent, Alberta, Middle east, Saudi Arabia 59

58

Sedimentary Rocks • Cherts: Chemically pure silica – cryptocrystalline – crystals visible only under magnification • Occurrence as small nodules or large masses parallel to bedding plane • Porosity due to fractures • Major pool – Offshore California, Monterey cherts

59

59