Publications

Banyumas Sub-basin is located on the southern volcanic belt of Java where petroleum exploration just recently began after stopped for a quite long time. The initial tectonic activity that influenced basin formation and architecture was the late Cretaceous-Oligocene subduction. The subduction process followed by the isostatic equilibrium during late Oligocene. Two main faults existence which have opposite trends : Muria-Kebumen Sinistral Fault trending SW-NE and Pamanukan- Cilacap Dextral fault trending NW-SE, respectively marked the isostatic process. These two faults assumed had sunk the northern part of Central Java and as the isostatic compensation also uplift the southern part because of the convergence of those opposing faults, it is proved by bouguer anomaly data +110 mgal on the southern side and gradually decreasing to -5 mgal at the northern side. Besides, these two faults phenomena also influenced the sub basins formation, one of them is Banyumas Sub-basin.Banyumas Sub-basin was intensively formed in Middle Miocene, mainly at the southern side of north Serayu Mountain, whereas the Majenang Depression and Besuki High as the axis of Banyumas Sub-basin. This depocenter was the area of thick sediment accumulation that deposited between transition to marine environments. Pemali Formation was deposited in transition to marine environments, consists of shale domination which is very potential as the main source rock of Banyumas Sub-basin. Intensive Neogene tectonic activity and overburden pressure supported the maturation of Pemali Formation. This formation predicted consists of a kerogen type II which potentially generated oil and gas prone. There are two potential reservoirs in Banyumas Sub-basin: Halang Formation which was formed in Middle Miocene, consists of volcanic sandstone, coarse sandstone, and calcareous sandstone, Kalipucang Formation which consists of reef limestone and bitumen content.Laterally the hydrocarbon migrated from Pemali Formation to Kalipucang Formation and vertically from Pemali Formation to Halang Formation. Furthermore, the hydrocarbon accumulation took place both in Besuki and Gabon Highs. This paper will examine and describe in detail the influence of tectonic activities and sedimentary process which happened in Banyumas Sub-basin and also the possibility of potential hydrocarbon accumulation.