THE PETROLEUM SYSTEMS AND FUTURE POTENTIAL OF THE SOUTH SUMATRA BASIN

摘要

This review is based on analysis of field and well data, palaeogeographic mapping, and seismic-based studies of structural history, maturity, migration pathways and trapping mechanisms. The mapped distribution and quality of source, reservoir and seal are reviewed to determine the critical factors constraining the basin's petroleum systems. Play-based creaming curves are used to estimate remaining potential.rnThe South Sumatra Basin contains a mixed terriginous, volcaniclastic and carbonate fill. Five plays account for the majority of discoveries to date. These are found in; Pre-Tertiary fractured basement, Oligocene to Early Miocene (Lower Talang Akar Formation) fluvio-deltaic sandstones, Early Miocene (Batu Raja Formation) carbonates and Early Miocene (Gumai Formation) and Middle Miocene (Air Benakat Formation) shallow marine sandstones.rnOligocene-Early Miocene age lacustrine and deltaic source rocks are recorded or implied by discovered oil characteristics. Source-rock type and distribution has influenced the distribution of hydrocarbons while in some areas hydrocarbon generation predates structure formation. The pinch-out of Oligocene and Miocene regional seals limit prospectivity on the eastern side of the basin.rnCumulative oil production has exceeded 2 BBO from an estimated original reserve of almost 3 BBO. Original gas reserves are estimated at 22 TCF, with less than 6 TCF produced to date. An estimated 6 to 10 TCF of gas and 0.2 to 0.5 MMB of oil remain to be discovered in proven plays.rnHistorically oil production dominated with associated gas being flared. More recently gas has been exported to Central Sumatra and Singapore. These new markets helped to stimulate exploration activity in the 1990's. Local markets are developing although considerable stranded gas remains to be exploited. Securing further gas markets will revive exploration activity.