Awang H. Satyana 1), Cipi Armandita 2), Budi Raharjo 2), and Ildrem Syafri 2)
[1) Exploration Badan Pelaksana Migas, Jakarta 2) Geology Dept. University of Padjadjaran, Bandung]
Recent detailed field studies in the Sumedang area and regional re-interpretation indicated new observations on the evolution of the Bogor Basin. The basic ingredient is that the Bogor Basin in its history ever received sediments from the northern provenance of the Northern Platform. This differs with Martodjojo (1984)’s conclusions stating that all Bogor’s sediments were sourced from the south. Turbiditic sediments of the upper Middle Miocene Cinambo, lower Pliocene Subang and Bantarujeg are examples of the exposed sediments in the area sourced from the north provenance. Older north-sourced sediments than those formations may also present. Lowstand levels in the Northern Platform has eroded the Talang Akar, Baturaja, Cibulakan, and Parigi sediments. The sediments were transported southward by submarine channels through the slope area between the platform and the Bogor Basin and were deposited in ponded basins possibly formed on the slope area and as submarine fans on the floor of the basin. The Baribis normal fault deforming the slope area had accommodated the transport of these gravity-flow sediments. The fault was inverted to become a back-arc thrust verging to the north in the Pleistocene. These new observations open the windows of opportunities for hydrocarbon exploration in the Bogor Basin. This is based on the analogue with the proven productive turbidite play like that in the Makassar Strait and other deep-water plays. Prolific reservoirs and good sources of the sub-basins of the Northern Platform like those in the Pasir Putih (Pasir Bungur and Kepuh) and Jatibarang had partly been eroded in lowstand levels, transported, and deposited as gravity flow sediments within the Bogor basin. With stratigraphic and structural trap formation, sealed by good top and lateral seals, charged by hydrocarbons generated within the basin, then these transported sediments will become good hydrocarbon prospects. Detail model of sedimentology and petroleum system of the Bogor Basin is required to justify the turbidite play, then seismic surveys and exploration drilling will prove the concept. This will influence all turbidite plays in the whole Java area.
* Buletin Geologi Institut Teknologi Bandung – Edisi Khusus 42 Tahun Pengabdian Prof. Dr. Soejono Martodjojo, M.Sc.
Departemen Teknik Geologi, FIKTM, ITB, Bandung, 2002