Sandstone Reservoir Distribution Mapping of Bekasap Formation Using Seismic Attributes and Identification of Stratigraphic Trap in ‘X’ Field, Central Sumatera Basin

The 'X' field is an oil-producing field in the Central Sumatra Basin. Central Sumatra Basin is the largest oil-producing sedimentary basin in Indonesia. The field is an area in the form of onlaping Bekasap Formation to the Basement High. The onlapping feature has potential for stratigraphic traps. This study aims to identify the potential stratigraphic traps for hydrocarbon accumulation, the distribution of sandstone reservoirs, facies types and the depositional environments. The data used in the study are 3D seismic data, well log, and core data. The research methods used including the analysis of electrofacies based on well log, seismic attributes, and conceptual geology model. The research shows that there is a stratigraphic trap in the form of intra-formation and regional traps. Intra-formation traps were formed vertically by the intersection of sandstone and shale lithologies and lateral facies changes, whereas the regional traps are formed by the shale layer of Telisa Formation and Bekasap Formation with onlapping on the Basement High. Based on AI inversion and RMS amplitude show the distribution of Top A sandstone reservoir is Northeast - Southwest on onlaping zone to the Basement High. The reservoir was deposited in depositional environment as wave dominated delta which is four facies associations: distributary channel, upper shoreface, lower shoreface, and offshore facies.