Curtin Petroleum Engineering

PETENG 101Introduction to Petroleum Engineering

Dr.MofazzalHossainSeniorLecturer,Email:md.hossain@curtin.edu.auTel:92664990

13 March 2012 Copyright 2010 Curtin University of Technology PETENG 101 1

PetroleumAccumulation,Generation,Migrationand

TrappingSupplementaryreading(downloadfromblackboard) SourceRocks Chapter3 Maturation,andMigration Chapter4

Curtin Petroleum Engineering

2

The Five Requirements for a Commercial Hydrocarbon Accumulation

1. amaturesourcerock,2. amigrationpathconnectingsourcerocktoreservoirrock,3. areservoirrockthatisbothporousandpermeable,4. atrap,and5. animpermeableseal.

Curtin Petroleum Engineering

3

Source Rocks - Definition

Anyfinegrainedrock

wheresufficientoriginal

organic matterhasbeen

accumulated,

preservedandthermally

matured0%

10%20%30%40%50%60%70%

Shale Carbonate Marl Coal

% Of World Petroleum Occurence

Curtin Petroleum Engineering

4

Petroleum Generation

Anoxicenvironment:oxygendecomposesorganicmatter(OM)

Adequatesedimentationrateoffinesediments: toolowarateexposestheOMtohostileagents;

toohigharatedilutestheOM

%ofOM: Shales:1 2% Carbonates:0.25%

Curtin Petroleum Engineering

5

Process of Maturation of OM

Involvesthermalconversionofbiologicalmolecules(kerogen)intopetroleumovertime

Kerogen:solidinsolublebituminousOMgeneratedduringtheinitialstagesofdiagenesis.Thereare4differenttypes: Type1(liptinite):formedfromalgae producesoil Type2(mixedliptinite/vitrinite):producesoilandgas Type3(vitrinite):formedfromcoal gasprone Type4(Inertinite):inert

Curtin Petroleum Engineering

6

PetroleumGenerationversusTemperature

Kerogenremainsunaltereduntilthesourcerockissubjectedtoincreasedtemperatures

Theexpectedpetroleumproductsdependonthetemperatureandtimeofexposure 0 45 60 100 175 225 315

G

e

n

e

r

a

t

i

o

n

I

n

t

e

n

s

i

t

y

Temperature (oC)

Petroleum Generation versus Temperature

Oil Wet Gas Dry Gas

Heavy LightBiogenicMethane

Curtin Petroleum Engineering

7

Depth,TimeandTemperature

0

2

4

6

8

105 10 20 30 40 50 60 70

D

e

p

t

h

(

k

m

)

Thermal Gradient (oC/km)

Oil Window as a Function of Geothermal Gradient65 oC 175 oC

5060708090

100110120130

0 40 80 120 160

T

e

m

p

e

r

a

t

u

r

e

(

o

C

)

Time (10^6 yr)

Peak Generation of Crude Oil

ReactionTimeHalved

ReactionRateDoubles

Curtin Petroleum Engineering

Hydrocarbon Generation vs Depth

Depth rangekm

.5

2

3.5

5

2

4

6

8

M

i

n

i

m

u

m

M

a

x

i

m

u

m

A

v

e

r

a

g

e

D

e

p

t

h

(

k

m

)

0

1

2

3

4

5

6

Generation Intensity

BiogenicMethane

Wet Gas

Methane

300

250

200

150

100

50

0

600 500 400 300 200 100

Cano-zoic

MesozoicPaleozoic

ImmatureOil Generation

Gas Generation

P

r

e

s

e

n

t

F

o

r

m

a

t

i

o

n

T

e

m

p

e

r

a

t

u

r

e

(

o

C

)

Time (millions of years from present)

Oil

Curtin Petroleum Engineering

9

Migration

Primary: theinitialmovementofhydrocarbonsfromthesourcerockintopermeablecarrierbedsandreservoirs

Thecausesofprimarymigrationisverypoorlyunderstood

Secondary: subsequentmovementofthehydrocarbonsthroughpermeablebeds.Thesecondarymigrationisdrivenbybuoyancyofthehydrocarbonfluids(oiland/orgas),sincetheyarelighterthanwater

Curtin Petroleum EngineeringCauses of Migration

Causesofprimarymigration Hydraulicforces Normalwatercirculation

CausesofSecondarymigrationarewidelyvaried entrainedparticles, capillarypressuredisplacementpressurephenomena, buoyancy, dissolvedgaseffects, accumulation, tiltedoilwatercontacts, stratigraphicbarriers, verticalmigration,and timeofoilaccumulation

13 March 2012 Copyright 2010 Curtin University of Technology PETENG 101 10

Curtin Petroleum Engineering

Secondary migration mechanisms (buoyancy)

13 March 2012 Copyright 2010 Curtin University of Technology PETENG 101 11

Curtin Petroleum Engineering

12

Migration Pathways

Curtin Petroleum Engineering

13

Migration Through Faults

Verticalmigrationcanoccurthrufaults,fractures,dykes,thrustplanes,etc.

Thiscanleadtosuperposedaccumulations

Curtin Petroleum Engineering

14

Seal - Definition

Anyimpermeable barrierwhichstopsthecontinuousupwardmigrationofpetroleum

Curtin Petroleum Engineering

15

Seal Geometry

Curtin Petroleum Engineering

16

Traps and Timing

Curtin Petroleum Engineering

17

Trap - Definition

Atrapisageometricconfigurationofrockssuitableforhydrocarbonaccumulationinwhichareservoirrockissurroundedandconfinedbyanimpermeablerocktype(seal)

Anunclosedgeometrymayalsobeatrapifpermeabilityvariationsblockofftheescapeoffluids

Curtin Petroleum Engineering

18

Petroleum Trap Types

3 types

1. Structural2. Stratigraphic3. Combination

Curtin Petroleum Engineering

19

Structural Traps

Anticline Normal Fault Growth FaultThrust Fault Salt DomeDiapir

Generated by local deformation of rocks

Curtin Petroleum Engineering

20

Stratigraphic Traps

Unconformity Pinchout Diagenetic Channel Reef

Formed by changes in stratigraphy, lithology or both

Curtin Petroleum Engineering

21

Trap Terminology (anticline)

Gas

Oil

Water

Closure

Pick or crest

Trough

Oil-Water Contact (OWC)

Lowest point is sometime called Spill Point

Gas-Oil Contact(GOC)

Reservoir

Curtin Petroleum Engineering

22

Trap Interpretation

Mapthetraps Determineclosureand,ifpossible,calculatevolumes

Mapofsealintegrityforriskpurposes Gaschimneysorseepscanindicatealeakyseal

Determineappropriateformationtimingrelativetosourcerocks(geohistory)

Curtin Petroleum Engineering

23

Major Sites of Petroleum Accumulations in Sedimentary Basins

4

14

50

11

21

0

10

20

30

40

50

60

Other Shelf Hinge Area Deep Basin Mobile Rim

%

Wheretofindthelightestoil?Andtheheaviestcrude?..

Curtin Petroleum Engineering

Class exerciseIdentify Basic Hydrocarbon Traps

Unconformity

Surface

Anhydrite

?Unconformity Trap

??Anticline Trap???Fault Trap

??Buried Reef

??

????Pinch Out

Grading Trap

??Sand Lens

??Salt Dome Traps Sub-SaltSediment Truncation

Curtin Petroleum Engineering

25

Thank you

Any question ?