Challenging of Tight Reservoir in Southern Sarawak, Offshore Malaysia, Unlocked by Geological Insights and Development Optimization

This study aims to evaluate the geological and diagenetic mechanisms controlling notably low permeability within clastic sedimentary reservoirs of the Early Miocene lower coastal plain in Lower Cycle II. The focus is on characterizing reservoir facies and tight reservoir distribution both vertically and horizontally and provide optimizing production strategies.

Key workflows include lithofacies identification and diagenetic feature analysis through petrographic analyses, XRD, and SEM, as well as electrofacies interpretation based on characteristic log response in non-core wells. Seismic inversion is utilized to define facies and property distributions, supporting the selection of technically viable production strategies.

The result indicate that the igneous intrusions are the primary factor of permeability reduction in lower coastal plain setting. These intrusions lead to thermochemical alteration and kaolinite enrichment. A comprehensive integrating geological context, petrophysical interpretation and seismic inversion reveals a widespread distribution of tight gas sand probability within specific interval in Lower Cycle II. The study enhances the accuracy of recovery volume estimation in low-permeability clastic systems and improve predictions of tight reservoir distribution in undrilled area. Additionally, advanced techniques such as hydraulic fracturing and horizontal drilling could potentially boost production rates by approximately 4 to 6 times over current estimates.