PREPARED BY : ROZEN REVILENE RAYMOND (15302) SUPERVISOR...
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PREPARED BY : ROZEN REVILENE RAYMOND (15302) SUPERVISOR : MDM. NORSYAZWANI BIN ZAINAL ABIDIN Petroleum Geoscience Department, Universiti Teknologi PETRONAS, Malaysia. DIAGENETIC HISTORY OF CARBONATE FORMATION IN EASTERN SABAH ABSTRACT This work presents the diagenetic history of Gomantong Limestone Formation located along the road of Sukau, Sabah. In early Miocene, there is a period of tectonic deformation which suggested widespread of uplift followed by carbonate sedimentation (Gomantong Limestone Formation) when the depositional environment changed from deep to shallow marine. Overall, diagenetic history in Gomantong Limestone is limited and restricted to marine diagenetic environment. Due to high cementation, reservoir quality of Gomantong is relatively poor. INTRODUCTION PROBLEM STATEMENT: The limestone from the Gomantong Formation in the eastern Sabah was deposited on an open shelf which is adjacent to the coastline formed of uplifted Labang Formation. Noad (2001) stated that due to lack of exposure of Gomantong Formation rocks thus leads to speculative on the age of the formation. However, detailed study on diagenetic features are still unavailable. OBJECTIVES: • To study the microfacies of carbonate in north east Sabah • To understand the diagenetic processes that occur in Gomantong Limestone during Miocene Period. METHODOLOGY FIELD WORK SELECTIVE ROCK SAMPLING • THIN SECTIONS • SEM (SCANNING ELECTRON MICROSCOPY) • X-RAY DIFFRACTION ANALYSIS • STRIKE & SLIP DIRECTIONS • SEDIMENTARY LOGGING CONCLUSION Generally, the diagenesis events are limited to cementation, dissolution, micritization, compaction and replacement. Diagenetic environment are said to be in marine environment due to the blocky and equant cements presence. Little diagenesis is due to lack of exposure. It is believed that Gomantong Limestone extended to western Sulu Sea, therefore is is recommended to have a more detailed study by including stable isotope analysis in future research. Overall, the reservoir quality is highly affected by the diagenesis which decreases the reservoir quality due to cementation. 24-0027 (D) - Calcite - CaCO3 - Y: 50.00 % - d x by: 1. - WL: 1.5406 - Hexagonal (Rh) - a 4.99000 - b 4.99000 - c 17.00200 - alpha 90.000 - beta 90. Operations: Strip kAlpha2 0.500 | Fourier 20.000 x 1 | Smooth 0.200 | Import S1 - File: 66.raw - Type: 2Th/Th locked - Start: 10.000 ° - End: 80.000 ° - Step: 0.020 ° - Step time: 1. s - Temp.: 25 °C (Room) - Time Started: 10 s - 2 Lin (Counts) 0 100 200 300 400 500 600 700 2-Theta - Scale 10 20 30 40 50 60 70 80 RESULT & DISCUSSION c B A THIN SECTIONS: Figure A: Wackestone with abundance of lepidocyclina sp. (Benthic foraminifera). Grains to grains contact indicate mechanical compaction and shallow burial. Equant-blocky cements filled in fractures and present of benthic forams indicate marine realm as diagenetic environment. Figure B: Packetsone with abundance of broken fragments of Lepidocyclina sp. Mechanical compaction causing the grain to grain contacts. Minor fractures then formed and infilled by calcite cements. Figure B: Boundstone where platy corals are bound together. Chambers of corals have been neomorphosed and infilled by calcite cements. Platy corals indicate depositon at fore reef and base of the slope environment. Diagenetic Environmentn Diagenetic Processess Diagenetic Environment Shallow Marine Shallow – Moderate Burial Moderate – Deep Burial Meteoric Influence Micritization Equant Blocky Calcite in Intergranular Grains Equant Block Calcite in Intragranular Grains Dissolution Mechanical Compaction & Fracturing Blocky calcite cement in fractures Stylolites Replacement by Pyrite SEM image illustrating blocky equant cements XRD analysis results showing that most of the cement is calcite and not influence by dolomitization Summary of diagenesis processes with its relative diagenetic environment proposed. SEM RESULTS: GEOCHEMICAL ANALYSIS : References: • Noad, J. (2001). The Gomantong Limestone of eastern Borneo: a sedimentological comparison with the near-contemporaneous Luconia Province. Palaeogeography, Palaeoclimatology, Palaeoecology, 175(1), 273-302. • Lavenu, A. P., Lamarche, J., Gallois, A., & Gauthier, B. D. (2013). Tectonic versus diagenetic origin of fractures in a naturally fractured carbonate reservoir analog (Nerthe anticline, southeastern France) AAPG bulletin, 97(12), 2207-2232.
Transcript of PREPARED BY : ROZEN REVILENE RAYMOND (15302) SUPERVISOR...
PREPARED BY : ROZEN REVILENE RAYMOND (15302) SUPERVISOR : MDM. NORSYAZWANI BIN ZAINAL ABIDINPetroleum Geoscience Department, Universiti Teknologi PETRONAS, Malaysia.
DIAGENETIC HISTORY OF CARBONATE FORMATION IN EASTERN SABAH
ABSTRACTThis work presents the diagenetic history of Gomantong Limestone Formation located along the road of Sukau, Sabah. In earlyMiocene, there is a period of tectonic deformation which suggested widespread of uplift followed by carbonate sedimentation (GomantongLimestone Formation) when the depositional environment changed from deep to shallow marine. Overall, diagenetic history in GomantongLimestone is limited and restricted to marine diagenetic environment. Due to high cementation, reservoir quality of Gomantong isrelatively poor.
INTRODUCTION
PROBLEM STATEMENT:The limestone from the Gomantong Formation in the eastern Sabah was depositedon an open shelf which is adjacent to the coastline formed of uplifted LabangFormation. Noad (2001) stated that due to lack of exposure of GomantongFormation rocks thus leads to speculative on the age of the formation. However,detailed study on diagenetic features are still unavailable.
OBJECTIVES:
• To study the microfacies of carbonate in north east Sabah• To understand the diagenetic processes that occur in Gomantong Limestone
during Miocene Period.
METHODOLOGY
FIELD WORK
SELECTIVE ROCK SAMPLING
• THIN SECTIONS• SEM (SCANNING ELECTRON
MICROSCOPY) • X-RAY DIFFRACTION ANALYSIS
• STRIKE & SLIP DIRECTIONS
• SEDIMENTARY LOGGING
CONCLUSION
Generally, the diagenesis events are limited to cementation, dissolution, micritization, compaction and replacement. Diageneticenvironment are said to be in marine environment due to the blocky and equant cements presence. Little diagenesis is due to lackof exposure. It is believed that Gomantong Limestone extended to western Sulu Sea, therefore is is recommended to have a moredetailed study by including stable isotope analysis in future research. Overall, the reservoir quality is highly affected by thediagenesis which decreases the reservoir quality due to cementation.
S1
24-0027 (D) - Calcite - CaCO3 - Y: 50.00 % - d x by: 1. - WL: 1.5406 - Hexagonal (Rh) - a 4.99000 - b 4.99000 - c 17.00200 - alpha 90.000 - beta 90.
Operations: Strip kAlpha2 0.500 | Fourier 20.000 x 1 | Smooth 0.200 | Import
S1 - File: 66.raw - Type: 2Th/Th locked - Start: 10.000 ° - End: 80.000 ° - Step: 0.020 ° - Step time: 1. s - Temp.: 25 °C (Room) - Time Started: 10 s - 2
Lin
(C
ounts
)
0
100
200
300
400
500
600
700
800
2-Theta - Scale
10 20 30 40 50 60 70 80
RESULT & DISCUSSION
c
B
A
THIN SECTIONS:
Figure A: Wackestone with
abundance of lepidocyclina sp.
(Benthic foraminifera). Grains
to grains contact indicate
mechanical compaction and
shallow burial. Equant-blocky
cements filled in fractures and
present of benthic forams
indicate marine realm as
diagenetic environment.
Figure B: Packetsone with
abundance of broken
fragments of Lepidocyclina sp.
Mechanical compaction
causing the grain to grain
contacts. Minor fractures then
formed and infilled by calcite
cements.
Figure B: Boundstone where
platy corals are bound together.
Chambers of corals have been
neomorphosed and infilled by
calcite cements. Platy corals
indicate depositon at fore reef
and base of the slope
environment.
Diagenetic
Environmentn
Diagenetic Processess
Diagenetic Environment
Shallow
Marine
Shallow –
Moderate
Burial
Moderate –
Deep Burial
Meteoric
Influence
Micritization
Equant Blocky Calcite in
Intergranular Grains
Equant Block Calcite in
Intragranular Grains
Dissolution
Mechanical Compaction &
Fracturing
Blocky calcite cement in
fractures
Stylolites
Replacement by Pyrite
SEM image illustrating blocky equant cementsXRD analysis results showing that
most of the cement is calcite and not
influence by dolomitization
Summary of diagenesis processes with its relative
diagenetic environment proposed.
SEM RESULTS:GEOCHEMICAL ANALYSIS :
References:• Noad, J. (2001). The Gomantong Limestone of eastern Borneo: a sedimentological comparison with the near-contemporaneous Luconia Province. Palaeogeography, Palaeoclimatology, Palaeoecology, 175(1), 273-302.
• Lavenu, A. P., Lamarche, J., Gallois, A., & Gauthier, B. D. (2013). Tectonic versus diagenetic origin of fractures in a naturally fractured carbonate reservoir analog (Nerthe anticline, southeastern France) AAPG bulletin, 97(12),
2207-2232.
