The Temana field is located on a structural high in the Balingian province, offshore Sarawak, Malaysia. Fault-sealing assessment of a normal fault in the Tertiary clastic rocks of the Temana field was carried out using shale smear parameters. Shale smear factor values of less than 6 and clay content ratio of greater than 30% on the fault surface indicate across-fault sealing of the reservoir rocks on sand-sand interfaces. Hydrocarbon column height estimated for sandstone pay zones from across-fault pressure difference is comparable to that calculated from the structural spillpoint (76 m; 249 ft). The fault seal thus appears to be efficient enough to support hydrocarbon columns filled down to the structural spillpoints of the reservoirs. Fault-rock permeability calculated from the available calibrations of the clay content-permeability relationship shows lower permeabilities of less than 0.3 md. Taking the Temana fault as a case in point, a new approach to evaluate fault-rock permeability probability (based on integration of clay content, fault displacement, and depth factors) is presented.