An overview of 20 years’ hydrocarbon exploration studies and findings in the Late Cretaceous-to-Tertiary onshore Central Sarawak, NW Borneo: 1997–2017 in retrospect

Abstract

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.

Relict hydrocarbon seeps in the Oligocene–Miocene Subis carbonate platform, Malaysia: Implications on hydrocarbon generation and migration pathways and potential sealing by shale gouging

“…The source rock potential of the onshore and offshore basins of NW Borneo were substantially analysed in the past; however, the studies were limited to coal layers and organic-rich shale sequences within clastic systems (Abdullah, 1999;Adepehin, Ali, Zakaria, & Sali, 2018 and references therein for the Nyalau Formation; Abdullah, 2003 on the Temburong Formation, Labuan; Adepehin et al, 2018 on Miri Formation;Hakimi et al, 2013, b;Sia & Abdullah, 2012;Sia, Abdullah, Konjing, & Koraini, 2014 on the Mukah and Balingian coalfields; Togunwa, Abdullah, Hail, & Jose, 2015 on the West-Baram Delta). In a compilation of pyrolysis data, while the Tanjong and Nyalau formations displayed a mixed gas-oil and oil window, the NW Borneo Miocene sediments were observed to predominantly fall in the gas window (Adepehin et al, 2018). An estimated 50% of global hydrocarbon reserves are presumed to be nestled in carbonate reservoirs and in the majority of these fields, the hydrocarbon is produced from carbonate source rocks (Huo et al, 2019;Jiang et al, 2008;Liu et al, 2017).…”

Sedimentary Environments and Paleoclimate Control of the Middle Miocene Balikpapan Group, Lower Kutai Basin (Indonesia): Implications for Evaluation of the Hydrocarbon Potential

“…The origin, generation, and preservation of hydrocarbons are significantly influenced by sedimentary environments because they control the formation and distribution of both source and reservoir rocks [1,2]. The Kutai Basin and the Mahakam Delta have been regarded as a significant hydrocarbon province, in which oil and gas are primarily of humic origin [3][4][5].…”

A New Method To Estimate Resistivity Distribution Of Shaly Sand Reservoirs Using New Seismic Attributes

“…From shallow to a deeper section, they are denoted as Sand-1 and Sand-2 in a setting of very gentle structure and stratigraphic layering. The gas generation originated from Cycle-1 and Cycle-II group source rocks and migrated through deep-rooted faults to Cycle V and Cycle VI sand reservoirs (Vahrenkamp, 1998;Joseph et al, 2019).…”