Abstract

Onshore and offshore sub-basins of Northwest Java contain at least ten active petroleum systems which have given rise to more than 150 separate oil and gas fields. The expected ultimate reserves of the region amount to over 4 BBOE, which represents about 14 BBOE in-place. Onshore Java sub-basins within the study area include the Ciputat, Kepuh, Pasir Bungur, Cipunegara/E15 Graben and Jatibarang. Oil and gas originating from these sub-basins have migrated through onshore structural highs, and onward in a northerly direction towards the offshore Northwest Java (ONWJ) region. Petroleum systems located within offshore sub-basins include the South Ardjuna, Central Ardjuna, Sunda, Yani/North Seribu Trough and Asri systems. In this paper, the ten major petroleum systems of Northwest Java have been characterized in terms of the type of source rock migration/carrier bed system, major reservoir and seal units, and style of entrapment. Results from each system are compared and contrasted to account for the relative volumes of hydrocarbons found to date, and the oil versus gas distribution of each system.