Publications

The Bangko region in the western part of the South Sumatra Basin is a proven hydrocarbon producer in the Jambi province. Since PetroChina Indonesia acquired the concession in June 2002, there has been aggressive activity to explore potential commercial hydrocarbons in the area. Commercial oil fields were discovered at the Piano oil field in late 2003 and at the West Piano oil field in early 2004. All this time, the main objective of PetroChina's exploration and production in the Bangko area has been only from the northern field by marine clastic deposits of the Gumai Formation. Therefore, a better geological understanding, including sedimentary sequence and facies distribution assessments, is important for the development of promising plays, especially those moving toward the middle of the Bangko Block. This study is the first synthesis focused on incised valleys developed within the frame of the high-stand system track to the low-stand delta or slope deposit Slendro and Bonang prospect. The incised-valley fill comprises low-stand and transgressive facies separated by a transgressive surface. The morphology of the valleys is strongly controlled by tectonics and relative sea level change. The Miocene (middle-early) sedimentary cover is thick and continuous, with a maximum area ranging between 2.5 and 4 kilometers in incised valley fills. Technically, the low-stand facies consist of a fluvial lag overlain by estuarine and shallow marine sandstone. Above the transgressive surface, thin transgressive shales were deposited as the relative sea level continued to rise. The interpretation of incised valley fills within the Gumai sandstone may lead to a better understanding of the geometry and reservoir characteristics for focusing gas exploration, resulting in a more efficient future gas exploration strategy in the Bangko area. Through this preliminary evaluation, we quantified P50 (at least a 50% probability recovered) of up to 400 billion cubic feet of gas prospective resources.