The study of petroleum geology of the Songkhla basin by used of well and geophysical data explains subsurface geology, geological structure, and basin evolution with additionally preliminary petroleum potential assessment. The Songkhla basin formed an elongate N-S trending and is a half-graben bounded to the west by the major extensional fault controlling the basin development and sedimentation. The Tertiary sedimentary sequence in the Songkhla basin is almost entirely non-marine sediments of alluvial fan dominated in the west while lacustrine and fluvial deposited from central to the east with occasionally marine transgression. The maximum thickness of accumulation is approximately 3,500 meters. The proposed stratigraphy is subdivided into 5 formation, namely: SK-1, SK-2, SK-3, SK-4, and SK-5 Formation in ascending order. From geochemical study, most of source are dark organic rich lacustrine claystone or shale. The source rock materials contain organic Type I/II/III kerogens that have a high potential for oil and gas generation. The source rock below 2,000 meters are mature enough to generate hydrocarbon. The sandstone reservoir are in the SK-1, SK-2 and SK-3 Formation and interbeded claystone or shale act as seal at the same time. Most hydrocarbon accumulations are in structural traps. As the results, the Songkhla basin is proven to possess some potential for oil generation.
