Petroleum systems of Indonesia

Indonesia contains many Tertiary basins, several of which have proven to be very prolific producers of oil and gas. The geology and petroleum systems of these productive basins are reviewed, summarized and updated according to the most recent developments. We have linked the recognized petroleum systems to common stages in the geological evolution of these synrift to postrift basins and classified them accordingly. We recognize four Petroleum System Types (PSTs) corresponding to the four main stages of geodynamic basin development, and developed variably in the different basins depending on their depositional environment history: (i) an oil-prone Early Synrift Lacustrine PST, found in the Eocene to Oligocene deeper parts of the synrift grabens, (ii) an oil and gas-prone Late Synrift Transgressive Deltaic PST, located in the shallower Oligocene to early Miocene portions of the synrift grabens, (iii) a gas-prone Early Postrift Marine PST, characteristic of the overlying early Miocene transgressive period, and (iv) an oil and gas-prone Late Postrift Regressive Deltaic PST, forming the shallowest late Tertiary basin fills. We have ascribed the petroleum systems in each of the basins to one of these types, recognizing that considerable mixing of the predominantly lacustrine to terrestrial charge has taken place. Furthermore, we have grouped the basins according to their predominant PSTs and identified “basin families” that share important aspects of their hydrocarbon habitat: these have been termed proximal, intermediate, distal, Borneo and eastern Indonesian, according to their palaeogeographic relationship to the Sunda craton of Southeast Asia.