Application of High-Resolution Sequence Stratigraphy (Hrss) for Reservoir Prediction in Group L & M, Block Pm309, Malay Basin

Abstract

The high-resolution sequence stratigraphic (HRSS) classification and correlation techniques, based on the principles of strata base level, volumetric partitioning and facies differentiation, can effectively improve the prediction of reservoir and increase opportunity of finding the subtle oil and gas reservoirs. Calibrating among core, well log correlation and seismic interpretation, identification of key sequence interfaces and reservoir mapping have successfully been applied to predict the distribution of effective reservoir in the Group L & M of Block PM309 in Malay Basin. This is the first detailed study done in Group L & M since its discovery and was conducted at the southeast of PM309, near Malaysia-Indonesia boundary. Seligi and Pulai are the two oil fields have been used in this study. The seismic stratigraphic units of Group L (younger) and M (older) were deposited in the lacustrine rift basin during the synrift phase. Below Group M, eight fourth order sequences were identified which mainly comprised of alternating thick sandstone and lacustrine shale packages. From Top Group M to L20 sand, two fourth order sequences were identified. The Group L facies include non-marine lacustrine offshore to deltaic, braidplain and minor lakeplain. Progradation of lacustrine sediments started from Top M up to the L70 sand. Above the L70 sand is a third order sequence boundary. Another third order sequence boundary was interpreted to be above the L20 sand. L20 sand package consists of thick laterally aggrading braided stream sandstone. Above the L20 sand, the younger sequences retrograde up to the top of the Group L. Twenty wells and four core description have been conducted in this study. Interpretation on L20 and M20 sand was done and correlatable with the well log. Based on the study, stratigraphic hydrocarbon traps was represented by sandstone bodies of deltaic and shoreface origin. From the deltaic environment, the traps are mostly from distributary channels and mouth bar bodies. The mouth bars (i.e M20 sand) were identified by their upward-coarsening trend from well logs and the deposition evolves mostly during the highstand systems track. Lacustrine shales act as seals to trap the hydrocarbon.