Characterizing Carbonate Reservoirs Through Sequence Stratigraphy and Seismic Attributes Analysis: From Example from the Miocene Carbonate of Central Luconia Province, Offshore Sarawak

Mohd R. Che Kob, Mohamad F. Idris, and Mohammad Y. Ali
Subsurface Technology, PETRONAS Research Sdn. Bhd., Selangor, Malaysia

The growth architecture, faulting and karstifications of a Miocene carbonate buildup of Central Luconia Province, offshore Sarawak, Malaysia has been studied using the 3D seismic data. The data were calibrated with core study and well-log analysis. Through the application of climate stratigraphy and the Cyclolog software, a high resolution well-to-seismic tie was obtained. This calibrated 3D seismic data were analyzed using sequence stratigraphy and seismic attributes analysis. The RMS (Root Mean Square) attribute, display the best image of the buildups morphology with distinctive zones for buildup and interbuildup areas. Spectacular arrays of facies heterogeneities across the buildup were also observed. The facies range from back reef lagoonal, reef front and off-reef facies. The extraction of seismic attributes at different stratigraphic level of the buildup shows the progressive growth architecture of the buildup from Early Miocene to Late Miocene. Analysis of the calibrated seismic facies reveals the association of the reservoirs with the mounded reefal and progradational facies. Evidence for porosity and permeability enhancements through karstification were also observed. The carbonates within the studied buildup were accumulated in two major sequences from Early Miocene to Late Miocene. It initial growths were corresponded to a major sea level rises in the Early to Middle Miocene. During the low relative sea level of the Late Miocene, the buildup was repeatedly exposed subaerially, and finally drowns during a major sea level rise at the beginning of the Pliocene. Three main factors controlled the growth and the architecture of the buildups; which are tectonics (faulting and subsidence), relative sea level and also the paleowind direction.

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