No abstract

This study outlines a sedimentological analysis of the Palaeogene West Crocker Formation (WCF) around the Kota Kinabalu area of SW Sabah, which represents a large submarine fan depositional system within part of what was the complex and tectonically active margin of NW Borneo. The newly acquired and often extensive outcrop data

An overview and integration of key petroleum exploration findings in the onshore Central Sarawak Basin, NW Borneo in the last 2 decades is presented. Findings revealed that critical moments for the generation and preservation of hydrocarbon may be found in the Early Oligocene, Early Miocene, and Late Miocene times. Geochemical data of ninety-five (95) source rocks suggest TOC values of 1.54 wt% (Miri Formation) to 70.00 wt% (Nyalau Formation) with promising S 2 and S 2 /S 3 ratios. T Max fell below the 435 °C maturation threshold. Reservoir facies of the Nyalau, Belait, and Lambir formations and their subsurface equivalents have moderate-to-poor poro-perm properties. Reservoir plays in the area are the Oligocene-Miocene clastics and limestones of Cycles I, II, III, and IV. Significant diagenetic modification is evident in analogue reservoir sandstones, and could constitute major poro-perm control in subsurface reservoir units. Observed predominance of structural related traps gleaned from seismic data is a reflection of the paleotectonic (Sarawak orogenic) event (ca. 40 − 36 Ma) associated with the region. Shale rocks overlying possible reservoirs and observed juxtaposition of reservoir units against impermeable beds provide seal integrity. Deeply seated faults are potential conduits, in addition to buoyancy. Concentration of future research efforts on petroleum/basin modeling and subsurface reservoir assessment was to further improve current understanding of the under-explored onshore Central Sarawak.