Assessing Hydrocarbon Source Rock Potential of the Upper Paleozoic Sedimentary Sequence in Keruak Hill, Terengganu, Malaysia

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ABSTRACT The mature source rock in the Malay Basin producing oil and gas is well‐documented, having been generated by lacustrine, fluvial‐deltaic, and fluvio‐marine environments, ranging from the Oligocene to the Miocene age. However, it would be interesting to study similar source rock environments from different geological ages. This could provide evidence for the Upper Paleozoic terrestrial sedimentary rock distributed in the eastern part of Malaysia, which has yet to be studied, especially in terms of source rock potential. Therefore, this study investigates the sedimentary facies and the hydrocarbon potential of Upper Paleozoic mudstone in Besut, Terengganu, Malaysia. Eight lithofacies were recorded at Keruak Hill, revealing a depositional environment of fluvial and floodplains. Twelve mudstone samples were collected and analyzed using a hydrocarbon source rock analyzer (HSRA) (i.e., Hawk Pyrolysis), total organic carbon (TOC), vitrinite reflectance (VR), and petrographic analysis to assess their hydrocarbon potential. The highest TOC values (ranging from approximately 1.64 wt% to 5.93 wt%) were found in eight samples from the Keruak Hill outcrop, indicating a promising source rock for hydrocarbon generation. One sample from Keruak Hill also exhibited promising Type II/III kerogens associated with gas production, whereas three samples plotted between Type III and IV in the area of dry gas. Thermal maturity analysis indicated that the Keruak Hill outcrops were in the immature to mature stage, with significant thermal maturation and a gas‐prone organic matter, and were identified as a mature source rock with potential for dry gas generation. The mean VR (VR o ) value of Keruak Hill ranges from 2.81% to 3.18%, indicating a late gas window to post‐mature stage. In contrast, T max values range from 260°C to 342°C and suggest immature kerogen based on T max –hydrogen index (HI) and T max –production index (PI) plots. Integrating TOC analysis, Rock‐Eval pyrolysis, thermal maturity assessment, and VR provides an accurate evaluation of the hydrocarbon generation potential of Upper Paleozoic mudstone in Setiu and Besut. This knowledge contributes to regional geology and aids future exploration and resource assessment efforts in the area for those looking for Upper Paleozoic source rock.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.