The Petroleum Systems of Onshore West Baram Delta, Northern Sarawak, Malaysia

A sequence stratigraphic investigation of the onshore Baram Delta integrated with modern biostratigraphic analysis suggests that the sedimentary section in SK333 has been affected by three major tectonic episodes of deformation:(i) Late Cretaceous to Eocene (79.5-36Ma) block faulting, (ii) Late Oligocene to Mid Miocene (30-20.5Ma) wrench movement and related folding followed by (iii) Mid Pliocene to Recent (4.0-0Ma) uplift and compressional folding. Subsequently, two optimum play trends have been mapped in SK333. These are the Miri–Asam Paya-Seria (MAS) and Engkabang Anticlinoria trend respectively, which are separated by the Badas Synclinorium, an abundant source kitchen area. To summarise the plays: The MAS Anticlinoria trend is an enhanced oil fairway with prolific oil charge from Late Miocene coals and peats on a confirmed oil migration fairway from the Badas Syncline. Reservoirs are excellent quality Mid Miocene to Early Pliocene shoreface-shelfal sands with deeper turbidite sand upside. The Engkabang Anticlinoria is mainly a deep tight gas play with inferred charge from overmature Eo-Oligocene basinal shales. This play is higher risk than the Miri Trend due to the potentially former depth of burial of the Eocene carbonate reservoir objective to approximately 5-6kms. This is inferred to have led to diagenetic inhibition of porosity.