Publications

Oil in the Telisa Formation in Suban Baru Field was discovered during the exploration and development phase of the fractured basement gas reservoir. The origin of oil in this reservoir is not clearly understood. The Talang Akar Formation, which was deposited in a fluvio-deltaic system, is a proven source rock for the prolific South Sumatra Basin. Current basin modeling of the Telisa Formation suggests that the marine source rock facies in the Suban Field is immature to early mature. However in the basin center, the Telisa Formation is modeled to be mature, although this has not been proven by any wells. Therefore, there is ambiguity as to whether the oil in Suban Baru was sourced by the Telisa Formation or a different source rock. This paper addresses the origin of oil in the Telisa Formation, and concludes that the oil does not originate from Telisa source rocks. A 3D basin modeling study was performed to better understand the petroleum system of Telisa Formation using existing data. The data consists of TOC, pyrolysis, and vitrinite reflectance (Ro) from seven wells across the Corridor Block. The geochemical data, including oil fingerprint analysis, was only available from wells drilled at the crest of the structures, so maturity data in the basin flanks was not directly measured. The available data was, however, helpful to identify the depositional environment of the source rock. The basin modeling of these facies suggests that the Telisa Formation is mature in the center of the basin to the southwest of the Suban Baru field. n-Alkane patterns indicate that the oil in the Telisa Formation in Suban Baru field is more consistent with a Talang Akar source. However, given that the Telisa source rock is modeled as being mature over a large portion of the basin to the southwest of Suban Baru, the next step for Telisa oil exploration is to confirm the maturity of the source facies in this basin, determine why adjacent structures have not been charged, and to use this information to determine the potential volumes of hydrocarbons from this basin and other similar basins in South Sumatra. The amount of hydrocarbons generated by the Telisa source rock could be significant and therefore this formation could be a future exploration target as a resource play in the basin.