Publications

The South Sumatra Basin, including the Central Palembang Sub-Basin, is widely recognized as one of the most prolific hydrocarbon basins in Indonesia with a fractured basement as one of the main target reservoirs. It may be analogous with surrounding areas, such as: Sumpal, Dayung and the Suban field which are gas bearing fields within basement interval (IHS, 2018). The basement is comprised of multicomplex basement lithology originating from continental fragment of Gondwanaland aged in Permian-Jurrasic. The basement has undergone intensive fracturing as a result of a compressional phase contributing to permeability value which is indicated with loss circulation while drilling and serictic alteration indication as result of hydrothermal fluids usually occured along fractures (Lutz et al., 2011). The research study area is equipped with 6 wells penetrating to Basement interval, but unfortunately most of them are plugged and abandoned without conducting any tests due to the basement potential being overlooked during exploration since the early 1980s. The B-1 well is the only discovery well in basement interval with cumulative gas flow production reaching to 20 mmcfgpd. The success of B-1 exploration is plausibly associated with overpressure mechanism having occurred in the Gumai interval. Gumai Fm is well distinguished as a major regional seal in the Central Palembang Sub-Basin with its thickness varying from 98 meter to 1100 meters. The wireline log responses using Eaton’s method depicts that top overpressure is revealed in Mid Gumai Formation correlated with disequilibirium compaction as it exceeded rate sedimentation which is more than 300 ft/mya. Furthermore, the Talang Akar Formation also contributes to the overpressure due to fluid expansion mechanism. This study addresses the relation of overpressure with sealing capacity instead of its drawbacks as captured in excessive thickness of Gumai Fm. It plays an important role in exaggerating sealing capacity in the research study area aligned with overpressure mechanism as reflected in B-1 well which is able to hold at least 400 meter of hydrocarbon column.