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Journal of Applied Sciences
  Year: 2017 | Volume: 17 | Issue: 4 | Page No.: 153-170
DOI: 10.3923/jas.2017.153.170
 
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Sedimentology and Reservoir Geometry of the Miocene Carbonate Deposits in Central Luconia, Offshore, Sarawak, Malaysia

Hammad Tariq Janjuhah, Ahmed Mohammad Ahmed Salim and Deva Parsed Ghosh

Abstract:
Background: Carbonate buildups in Central Luconia are proven prolific hydrocarbon reservoirs, represented by thick limestone deposits with a minor proportion of dolomitic limestone. The limestone diversity attracted the considerable attention of oil and gas companies and geologists from all over the world. However, owing to many changes in lithology, facies characteristics and reservoir prediction of this formation, industry players still face challenges to identify and corroborate the lithology, facies and reservoir occurrence. Objective: To have better understanding on the reservoir quality and to increase hydrocarbon production, the current study aims to identify the lithofacies, depositional environment and diagenetic process which influence the reservoir rock. Methodology: Core description was conducted, core plugs were collected and thin sections of these core plugs were prepared. Results: The Central Luconia carbonates are divided into 8 facies. Based on the sedimentary structure, texture, components and fossils contents, 5 facies are identified in well A and B, namely: (1) Coated grain packstone, (2) Coral massive (m) lime grainstone, (3) Oncolite lime grain packstone, (4) Skeletal lime packstone and (5) Coral platy (p) lime mud packstone. Facies 4 is the dominant facies types in well A and B. Biota includes red algae, coral, foraminifera, echinoderm, sponge, green algae, bryozoans and bivalve. Visible porosity is from poor to very good. It varies in different facies with common open moulds and small vugs. However, low (Facies 1 and 5) to moderate (Facies 2, 3 and 5) permeability valves suggests that matrix porosity provides only limited interconnection between the large moldic pores. Many pores appear to form an early leaching of foraminifera and corals in facies 2 and 4. Conclusion: Deposition environment is interpreted to be lagoonal condition for these facies based on the features of the biotic assemblage. Lithofacies indicate a good quality reservoir, but diagenesis plays an important role in creating and destroying porosity. The main diagenetic processes affecting the reservoir quality are compaction including stylolite and cementation of calcite and dolomite. Whereas the dissolution is the main diagenetic processes in improving porosity and mechanical compaction enhancing permeability by forming small fractures.
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How to cite this article:

Hammad Tariq Janjuhah, Ahmed Mohammad Ahmed Salim and Deva Parsed Ghosh, 2017. Sedimentology and Reservoir Geometry of the Miocene Carbonate Deposits in Central Luconia, Offshore, Sarawak, Malaysia. Journal of Applied Sciences, 17: 153-170.

DOI: 10.3923/jas.2017.153.170

URL: https://scialert.net/abstract/?doi=jas.2017.153.170

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