A study on petroleum exploration potential of Barito Basin in southeastern Kalimantan, Indonesia: comparison of petroleum system with adjacent Kutai Basin

Abstract

The Kutai and Barito basins are the Cenozoic rift basins in southeastern Kalimantan, Indonesia and are very mature for hydrocarbon exploration history. Both basins have experienced similar structural evolution and depositional history. Despite the similarity between two basins, large oil and gas fields were found in the Kutai Basin, whereas not common in the Barito Basin and localized in its northeastern part. Depositional history of both basins evolved from lacustrine syn-rift to marine post-rift stages through fluvio-deltaic transitional environment. However, different type of petroleum system has been identified in the Barito and Kutai basins. Syn-rift lacustrine to fluvio-deltaic sequence (Tanjung Formation) is an essential element of petroleum system in the Barito Basin and post-rift deltaic sequence (Balikpapan and Kampung Baru formations) is a key element in the Kutai Basin. Such difference in the petroleum system type is associated with difference in burial history, affected by spatio-temporal variation of uplifting and basin subsidence. The differential uplifting of the Meratus Mountains allowed the syn-rift Tanjung Formation to reach thermal maturation only in the northeastern Barito Basin. The uplifting of the Central Kalimantan Mountains, however, caused erosion of the syn-rift sequence in the Kutai Basin and supplied enough sediments to form the post-rift deltaic sequence with thermal maturity. Future exploration potential of the Barito Basin still remains in the well-known, syn-rift Tanjung Formation and needs to be further evaluated from the pre-Cenozoic fractured basement, the post-rift Warukin, and the Berai limestone reservoirs particularly in the western region of the Barito Basin.