This study provides novel insights into the potential hydrocarbon reserves situated offshore West Sarawak, encompassing S.W. Sarawak, Tatau, West Luconia, and N.W. Luconia provinces. The exploration phases in the area of interest vary among the provinces. West Luconia, being relatively well-explored, has yielded gas discoveries. In contrast, South West (SW) Sarawak has seen oil discoveries, yet this region faces limitations in available data, and the associated petroleum system remains to be evaluated. Consequently, the primary objective is to evaluate the untapped hydrocarbon potential through a cohesive play-based methodology, extending to lead/prospect assessment.

The methodology revolves around process-based geological modeling, incorporating Forward Stratigraphic Modeling (FSM source-to-sink), integrated Petroleum System Modeling (PSM), and a comprehensive assessment of uncertainties across multiple parameters. The models are built using input data derived from regional geodynamic evaluations, defining structural styles, identifying sedimentary source locations, GDE mapping of various plays, standardized interpretations of horizons and faults, geochemical data, Pressure and Temperature data, and information from discovery data (including volumes in place, API, GOR, CGR, and non-hydrocarbon concentrations). The model outcomes, including the initial distribution of Total Organic Carbon (TOC) and Hydrogen Index (HI) in reservoirs, seals, and source rocks, undergo calibration based on observed petroleum system components from well data and seismic analysis.

The study has identified 8 main plays, with associated sub-plays, from Pre-Cycle I (Late Cretaceous to Eocene), Cycle I, II and III (Oligocene to Lower Miocene), Cycle IV, with associated carbonate pinnacles, and younger Cycles (V to VIII).

The main unconformities (Late Eocene and Middle Miocene - MMU) and related tectonic features have an impact on the HC charge mechanism of the reservoirs present in the various Cycles. The depositional environments during Pre-Cycle I have led to the preservation of source-rocks of terrestrial type with significant potential locally, which can contribute to the charge of younger cycles when burial history is adequate, especially in SW Sarawak. Local source-rocks of terrestrial origin (coals) are present in SW Sarawak grabens and are able to charge the grabens with liquid within a depth window of 2500- 3000m.

A 3D forward stratigraphic model (FSM) has been generated to simulate the evolution and facies distribution of the Eocene – Miocene interval calibrated with well and seismic data. The FSM results provide an integrated comprehension of the distribution of potential source rock, reservoir and seal intervals in the South-West Sarawak basin opening perspectives to evaluate the whole hydrocarbon prospectivity of this frontier area.

The results from FSM & PSM offer a comprehensive understanding of the distribution of potential source rock, reservoir and seal intervals in the South-West Sarawak basin offering insights to assess the overall hydrocarbon potential of this area.