Case Studies of Pakistan Carbonates

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LOGO

Multiple phases of dolomite fronts in the Samana Suk Formation Multiple phases of dolomite fronts in the Samana Suk Formation Multiple phases of dolomite fronts in the Samana Suk Formation Multiple phases of dolomite fronts in the Samana Suk Formation

(mid(mid(mid(mid----Jurassic): Possible reservoir analogue in the Margalla Hill Jurassic): Possible reservoir analogue in the Margalla Hill Jurassic): Possible reservoir analogue in the Margalla Hill Jurassic): Possible reservoir analogue in the Margalla Hill

Ranges, Pakistan.Ranges, Pakistan.Ranges, Pakistan.Ranges, Pakistan.

Multiple phases of dolomite fronts in the Samana Suk Formation Multiple phases of dolomite fronts in the Samana Suk Formation Multiple phases of dolomite fronts in the Samana Suk Formation Multiple phases of dolomite fronts in the Samana Suk Formation

(mid(mid(mid(mid----Jurassic): Possible reservoir analogue in the Margalla Hill Jurassic): Possible reservoir analogue in the Margalla Hill Jurassic): Possible reservoir analogue in the Margalla Hill Jurassic): Possible reservoir analogue in the Margalla Hill

Ranges, Pakistan.Ranges, Pakistan.Ranges, Pakistan.Ranges, Pakistan.

Dr. Mumtaz Muhammad ShahDr. Mumtaz Muhammad ShahDr. Mumtaz Muhammad ShahDr. Mumtaz Muhammad Shah

Department of Earth SciencesDepartment of Earth SciencesDepartment of Earth SciencesDepartment of Earth Sciences

QuaidQuaidQuaidQuaid----iiii----Azam University, IslamabadAzam University, IslamabadAzam University, IslamabadAzam University, Islamabad

(PAKISTAN)(PAKISTAN)(PAKISTAN)(PAKISTAN)

[email protected]

CONTENTSCONTENTSCONTENTSCONTENTS

INTRODUCTION1

FIELD OBSERVATIONS, PETROGRAPHIC STUDIES3

CONCLUSIONS AND FUTURE PERSPECTIVES6

GEOLOGICAL SETTINGS2

POROSITY, PERMEABILITY DETERMINATION4

DISCUSSIONS5

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INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION –––– Dolomite interest in Dolomite interest in Dolomite interest in Dolomite interest in

petroleum industrypetroleum industrypetroleum industrypetroleum industry

x2

4444

DOLOMITIZATION PROCESSESDOLOMITIZATION PROCESSESDOLOMITIZATION PROCESSESDOLOMITIZATION PROCESSES

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5555

Introduction Introduction Introduction Introduction –––– Our workOur workOur workOur work

�Dolomite facies parallel to bedding and along fault Dolomite facies parallel to bedding and along fault Dolomite facies parallel to bedding and along fault Dolomite facies parallel to bedding and along fault

systemsystemsystemsystem

�Jurassic marine carbonatesJurassic marine carbonatesJurassic marine carbonatesJurassic marine carbonates

�Scope of the workScope of the workScope of the workScope of the work

� Petrographical characterization of dolomite facies� Petrophysical characterization of dolomite facies

=Prospective work on the object

LOCATION OF THE LOCATION OF THE LOCATION OF THE LOCATION OF THE

STUDY AREASTUDY AREASTUDY AREASTUDY AREA

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7777

PANORAMIC VIEW OF BEDDING PARALLEL

DOLOMITE IN THE SAMANA SUK FORMATION

EHATA AREA

DARRA AREA

Dol.

Lm St.

Dol.Lm St.

Lm St.

FIELD OBSERVATIONSFIELD OBSERVATIONSFIELD OBSERVATIONSFIELD OBSERVATIONS

Dol.

Lm st.

CEMENT FACTORY CEMENT FACTORY CEMENT FACTORY CEMENT FACTORY

SECTIONSECTIONSECTIONSECTION

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FIELD

OBSERVATIONS

Dol.

Lm St.

Dol.

Dol.Lm St.

Dol.

Dol.

Lm St.

Lm St.

Lm St.

FIELD OBSERVATIONSFIELD OBSERVATIONSFIELD OBSERVATIONSFIELD OBSERVATIONS

Dol. I

Dol. II

SD

Dol. I

SD

Dol. I

Cal.

Dol.

Lm St.

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11111111

CATACLASTIC DOLOMITECATACLASTIC DOLOMITECATACLASTIC DOLOMITECATACLASTIC DOLOMITE

Brecciation in dolomite bodies due to faulting/fracturing

MACROSCOPIC/MICROSCOPIC OBSERVATIONSMACROSCOPIC/MICROSCOPIC OBSERVATIONSMACROSCOPIC/MICROSCOPIC OBSERVATIONSMACROSCOPIC/MICROSCOPIC OBSERVATIONS

PPL & CL Photomicrographs showing different calcite and dolomite phasesPPL & CL Photomicrographs showing different calcite and dolomite phasesPPL & CL Photomicrographs showing different calcite and dolomite phasesPPL & CL Photomicrographs showing different calcite and dolomite phases

Dol. I

Dol. II

HTC

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CL & PPL Photomicrographs showing different dolomite and calcite phases.CL & PPL Photomicrographs showing different dolomite and calcite phases.CL & PPL Photomicrographs showing different dolomite and calcite phases.CL & PPL Photomicrographs showing different dolomite and calcite phases.

HTC

Dol. II

Dol. I

Dol. I

HTC

HTC

Intercrystalline porosity in matrix dolomite

Pore-filling calcite in between dolomite crystals

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Multiple stages of dedolomitization Multiple stages of dedolomitization Multiple stages of dedolomitization Multiple stages of dedolomitization –––– M. M. Shah, 2013M. M. Shah, 2013M. M. Shah, 2013M. M. Shah, 2013

EFFECT OF

DEDOLOMITIZATION

ON RESERVOIR

PROPERTIES

Dissolution associated with dedolomitized part of dolomite crystals

Removal of late stage (TC) further enhance reservoir character

16

SELECTIVE DISSOLUTION

Multiple stages of dedolomitization Multiple stages of dedolomitization Multiple stages of dedolomitization Multiple stages of dedolomitization –––– AAPG Conference, Barcelona (8AAPG Conference, Barcelona (8AAPG Conference, Barcelona (8AAPG Conference, Barcelona (8----10, April 2013)10, April 2013)10, April 2013)10, April 2013)

RELATED TO EARLY PHASE OF

DEDOLOMITIZATION

DUE TO UPLIFT OF THE REGION AFTER

OLIGOCENE

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POROSITYPOROSITYPOROSITYPOROSITY----PERMEABILITY PERMEABILITY PERMEABILITY PERMEABILITY

ANALYSESANALYSESANALYSESANALYSES----

STATISTICAL APPROACHSTATISTICAL APPROACHSTATISTICAL APPROACHSTATISTICAL APPROACH

18181818

PorosityPorosityPorosityPorosity----permeability analyses (permeability analyses (permeability analyses (permeability analyses (ΦΦΦΦ, K) , K) , K) , K) ––––

Comparison with existing dataComparison with existing dataComparison with existing dataComparison with existing data

from Woody et al. (1996) in Warren (2000)

0,1

1

10

100

1000

0 5 10 15 20 25 30

Porosity (%)

Per

mea

bilit

y (m

D)

Interlocking saddle Dolomite

Zebra Dolomite

Sucrosic Dolomite

Lucia (1999) fits

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19191919


Porosity correction (calcite cement)Porosity correction (calcite cement)Porosity correction (calcite cement)Porosity correction (calcite cement)

Mean=6.1±3.1%

Mean=13.4±6.9%

0

5

10

15

20

25

30

Breccia Saddle Saddle Zebra Zebra Zebra Zebra Zebra Zebra Zebra

Por

osity

(%

)

Corrected Porosity (%)

Measured He Porosity (%)

20202020


Porosity correctionPorosity correctionPorosity correctionPorosity correction

y = 1,2349x + 6,4159R2 = 0,4175

0

5

10

15

20

25

30

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Measured He Porosity (%)

Cor

rect

ed P

oros

ity (

%)

Série1

Linéaire (Série1)

0,1

1

10

0 5 10 15 20 25


Cal

cula

ted

Per

mea

bilit

y (m

D)

Calculated Permeability (mD) Interlocking

Calculated Permeability (mD) Zebra

Real values

y = -0,0022x2 + 0,248x - 0,2183

R2 = 0,5517

y = 0,0002x2 + 0,0615x + 0,1752

R2 = 0,2408

0,1

1

10

0 2 4 6 8 10 12 14

Porosity (%)

Per

mea

bilit

y (m

D)

Saddle Dol.

Zebra Dol.

Polynomial (Zebra Dol.)

Polynomial (Saddle Dol.)

12

3

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21212121


Porosity correction: InterpretationPorosity correction: InterpretationPorosity correction: InterpretationPorosity correction: Interpretation

0,1

1

10

100

1000

0 5 10 15 20 25 30


Cal

cula

ted

Per

mea

bilit

y (m

D)

Calculated Permeability (mD)Interlocking

Calculated Permeability (mD) Zebra

Real values

Interboundarypores

22222222


Importance of breccias / cataclastsImportance of breccias / cataclastsImportance of breccias / cataclastsImportance of breccias / cataclasts

from Woody et al. (1996) in Warren (2000)

0,1

1

10

100

1000

0 5 10 15 20 25 30

Porosity (%)

Per

mea

bilit

y (m

D)

Interlocking saddle Dolomite

Zebra Dolomite

Sucrosic Dolomite

Cataclastic

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23232323

POROSITYPOROSITYPOROSITYPOROSITY----PERMEABILITY ANALYSESPERMEABILITY ANALYSESPERMEABILITY ANALYSESPERMEABILITY ANALYSES

Type Dolomite Sample Xll sizeTexture

Modification Cement type +% Porosity Type E.Porosity % Ø (%) Jmicro P% k (mD) Corrected P%

(µm) Visual (He) Point count cement+ØI. Sucrosic

RQ40 400-500 Pptation Fill + 7% Intercrystalline 7% 5% 6,66 0,43 11,5RT76 100-200 Cataclastic Sparry + 15% Intercrystalline 12% 3% 7,71 15

II. Interlocking RQ35 100-300 Dissolution Unfilled intercrystalline + Vuggy 4% + 5% 3,5 6,24 0,27 4

400-600RQ42 50-100 Dissolution Microgranular + 10% Intercrystalline + Vuggy 10% + 15% 11,43 10

200-300 2-5%RH103 200-300 Diss./Pptation Telogenetic/ fract Recryst. reduced sec. interxlline 1-2% 2,37 2RQ29H 100-200 Cata./ Diss. Granular + 15% Intercrystalline 7% 4% 6,59 0,17 10,7

20-50RQ30 100-500 Cata./ Diss. Fill + 12% Intercrystalline 12-15% 3,3 3,25 0,14 15RQ28 600-800 Cataclastic Sparry + 10% intercrystalline 7% 8% 10,58 0,19 17RQ26 100-300 Cata./ Diss. Telogenetic/ Fracture Channel/ Fracture 4% 1% 6,01 0,01 4RQ44 200-400 Dissolution Unfill Vuggy + Intercrystalline 5% + 4% 3% 7,13 0,17 4RQ45 500-600 Dissolution Sparry + 10% Vuggy + Intercrystalline 15% + 5% 7% 11,8 17

III. Zebra RH100 200-300 Diss./ Pptation Intercrystalline 3% 1,92 3

700-900 1,03RQ36 25-75 Dissolution Sparry + 15% Intercrystalline 10% 13% 28

500-600RQ41 100-200 Dissolution Sparry + 10% vuggy + Intercrystalline 20% + 12% 11 18,09 0,9 12

400-500 vuggy 2-3% 8,68RQ33 100-300 Dissolution Fill + 12% Intercrystalline 11% 3% 11,24 0,28 15

400-700 1-3% 7,6

24242424

� Field studyField studyField studyField study� dolomites restricted to bedding planes� Multiple phases and cataclastic nature of dolomites indicate episodic and

high pressure dolomitising fluids.� Multi-phase fluid flow (hydrofracturing, breccias)

� 3 dolomite textures: Coarse Xlline, Interlocking Saddle, Fine Xlline.3 dolomite textures: Coarse Xlline, Interlocking Saddle, Fine Xlline.3 dolomite textures: Coarse Xlline, Interlocking Saddle, Fine Xlline.3 dolomite textures: Coarse Xlline, Interlocking Saddle, Fine Xlline.� Various dolomite associated diagenetic events and calciteprecipitation� Petrophysical differences

� Reservoir propertiesReservoir propertiesReservoir propertiesReservoir properties� outcrop → meteoric calcite plugging� Dolomite brecciation and dissolution/precipitation played a key role in

porosity distribution.� Porosity corrections → limited properties however...

LESSONS LEARNTLESSONS LEARNTLESSONS LEARNTLESSONS LEARNT

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FUTURE PERSPECTIVESFUTURE PERSPECTIVESFUTURE PERSPECTIVESFUTURE PERSPECTIVES

� Establishment of detailed paragenetic sequence

� Relationship between diagenetic events and porosity enhancement

� Geochemical studies and isotopic analyses

� Detailed numerical modeling

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Case Studies of Pakistan Carbonates

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