“Fractured basement” play in the Sabah Basin? – the Crocker and Kudat formations as hydrocarbon reservoirs and their risk factors

Abstract

Exploration activities in the Sabah Basin, offshore western Sabah, had increased tremendously since the discovery of oil and gas fields in the deepwater area during the early 2000s. However, the discovery rates in the shelfal area have decreased over the years, indicating that the Inboard Belt of the Sabah Basin may be approaching exploration maturity. Thus, investigation of new play concepts is needed to spur new exploration activity on the Sabah shelf. The sedimentary formations below the Deep Regional Unconformity in the Sabah Basin are generally considered part of the economic basement which is seismically opaque in seismic sections. Stratigraphically, they are assigned to the offshore Sabah “Stages” I, II, and III which are believed to be the lateral equivalents of the pre-Middle Miocene clastic formations outcropping in western Sabah, such as the Crocker and Kudat formations and some surface hydrocarbon seeps have been reported from Klias and Kudat peninsulas. A number of wells in the inboard area have found hydrocarbons, indicating that these rocks are viable drilling targets if the charge and trapping mechanisms are properly understood. This study assesses the potential and risks of a conceptual “basement” hydrocarbon play in the Crocker and equivalent formations in the Sabah Basin.