Post on 14-Apr-2018
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BATUAN KARBONATKRISTIAN N TABRI
Appl ied Geolog y Research Div is ion
Faculty o f Earth Science and Technolog y
Ins t it u t Tekno log i Bandung
2011
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Geologic Aspects of CarbonateReservoirs: General Introduction: Concept of carbonates and carbonate
deposition
Carbonate Rock Types: Characteristics, Classification and Origin ofCarbonate Rocks
Carbonate Rock Resevoir Geometry: concepts of carbonate
platforms, build-ups, reefs and banks and sequence of stratigraphy Carbonate Sedimentation, Diagenesis and Dolomitization.
Carbonate Porosity Types, Classification (Choquette and Pray,1976), Characteristics, heterogenity and Origin.
Exploration concepts, strategy and tactics and development ofcarbonate plays
Geologic modeling of carbonate reservoirs using seismic, well logs(sample log, wireline logs, FMI etc), cores biostratigraphic and otherdata.
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GENERAL INTRODUCTION
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GENERAL INTRODUCTION:
Concept of carbonate rocks and
Concept of carbonate
deposition
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CONCEPT OF CARBONATE ROCKS
CARBONATE ROCKS OF CARBONATES ARESEDIMENTARY ROCKS WHICH CONSISTS OFCARBONATE MINERALS.
THEY COMPRISE OF LIMESTONESANDDOLOSTONES (DOLOMITES). CARBONATE ROCKS ARE PRACTICALLY
MONOMINERALIC CONSISTING OF CALCIUMCARBONATE MINERALS WITH FEW INSERTION OFMAGNESIUM IN THE CRYSTAL LATTICE.
CARBONATES ARE CHARACTERIZED ANDDIFFERENTIATED BY ITS FABRIC AND TEXTURERATHER THAN BY ITS MINERAL COMPOSITION.
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CHARACTERISTICS OF
CARBONATE ROCKS
CARBONATE ROCKS COMPRISES LESSTHAN 30% OF THE STRATIGRAPHICSECTION.
WIDE-SPREAD CARBONATE ROCKSINDICATE A SPECIAL TECTONIC CONDITION:TECTONIC QUISCENCE.
CARBONATE ROCKS ALSO INDICATE ASPECIAL DEPOSITIONAL ENVIRONMENT:CLEAR, WARM AND GENERALLY SHALLOWMARINE DEPOSIT.
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LIMESTONE IN RELATION TO SILICI-
CLASTICS
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LIMESTONE
MARL
RELATIONSHIP
The term marl is not usedin the petroleum industry or
American literature, the
term calcareous shale is
used instead.
Marl is used as a special
term for lacustrine shales
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CARBONATE SEDIMENTATION
CARBONATE SEDIMENTATION IS CONTROLLED BY A SINGLECHEMICAL EQUILIBRIUM EQUATION:
H+ + HCO3- + Ca2+ CaCO3 + H2O + CO2Increase of CO2 concentration in the solution will shift the equation to the
left, resulting dissolution of the calcium carbonates.
Increase of CO2 concentration may due to increasing depth (PCO2)
Input of meteoric water or input of CO2 due decay of organic materila
Decreas of CO2 concentration will shift the equation to the right, resultinginto carbonate deposition
Decrease of CO2 concentration may be due to:
Evaporation, increase of temperature due heating of the sea water by the
sun, escpecially in shallow waters
CO2 capture by organism, especially algae for photo-synthesis
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CHEMICAL CONTROLS OF
CARBONATE SEDIMENTATION
DEPOSITION AND DISSOLUTION ARE CONTROLLEDBY Concentrations of Ca ++ ions
Concentrations of CO3
ions SATURATION OF Ca ++ IONS IS CONTROLLED BY
Evaporation and
Temperature
SATURATION OF CO4 IONS IS CONTROLLED BY
PARTIAL PRESSURE, Temperature,
Atmospheric and
Biogenic activities/ particularly photosynthesis.
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CARBONATE CHEMICAL
ENVIRONMENT OF DEPOSITON
CARBONATES ARE DEPOSITED IN
HIGH Ph SALINE ENVIRONMENT.
CARBONATES ARE GENERALLYDEPOSITED IN MARINE
ENVIRONMENT.
SOME CARBONATES ARE ALSODEPOSITED IN LACUSTRINE SALINE
ENVIRONMENT.
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CARBONATE COMPENSATION
DEPTH
IN OCEANS: Partial pressure of CO2 increases with depth.
Temperature decreases with depth.
HENCE: Solubility of carbonate minerals (arragonite and
calcite) increases with depth.
CARBONATE MINERALS ARE DISSOLVED AT
CERTAIN DEPTH CALLED RESPECTIVELY : Arragonite Compensation Depth (ACD)
Calcite Compensation Depth (CCD)
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CARBONATE DEPOSITONAL
ENVIRONMENTS
Carbonates are generally warm water
sediments.
Carbonates are generally shallow water
sediments; deep water carbonates are
restricted to pelagic limestones.
Carbonates are generally deposited in
clear marine waters, free of fine clastics
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GEOCHEMICAL CYCLE OF
CARBON ATES
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WORLD WIDE DISTRIBUTION OF
CARBONATE SEDIMENTATION
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WET TROPICAL AREAS COINCIDING WITH WITH
REGIONS OF ABUNDANCE OF SILICICLASTIC INPUT
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DEPTH DISTRIBUTION OF
CARBONATE SEDIMENTATION
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CARBONATE
COMPENSATION
DEPTHragonite
Calcite
Isocline
ACD
ATLANTIC OCEAN
Degree of Saturation
D
e
p
th
I
n
Km
CCD
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SEDIMENTARY PROCESSES OF
CARBONATES
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PROCESSES OF CARBONATE
DEPOSITION
SECRETION - SKELETAL COMPONENTS
ACCRETION NON-SKELETAL COMPONENTS AGREGATION- SKELETAL & NON-SKELETAL
PARTICULATION NON-SKELETAL
: