Analysis Of Oil And Gas Accumulation Rule In Barito Basin And The Key Controlling Factors

Based on the theory of petroleum geology, structural geology and sedimentary petrology, by collecting, translating and analyzing a large number of public paper, according to the results of the previous studies, this paper firstly analyzes the basic geological conditions of the Barito basin, including the regional tectonic background, tectonic characteristics and evolution, the stratigraphic and sedimentary features, then analyzes the petroleum geological conditions of the basin, concludes the hydrocarbon accumulation rule and the key controlling factors. At the end of the paper, the remain exploration potential and the favorable exploration areas are disscussed.During the Paleogene period, Indo-Australian plate subducted under the Eurasian plate, a series of NW-SE trend rifts had been developed in the eastern Sunda continent, the Barito basin was formed. From Paleogene to now, the evolution of Barito basin was divided into four stages, namely rift period, transition period, depression period and extrusion period.The late-Paleocene to early-Eocene lower Tanjung formation mudstone and coals of the south Barito basin are the main source rock, the Early-middle Miocene lower Warukin shale and coals, middle-late Eocene upper Tanjung formation are the secondary source rock of the basin. The main reservoirs of the basin are lower Tanjung formation sandstone, the secondary reservoirs are Warukin formation sandstone and the Cretaceous granite. The local seals are lower Tanjung formation shale and Warukin shale. The regional seals are the thick marine shale of upper Tanjung formation.There are three types of traps developed in Barito basin, including extrusion anticline trap, fault trap and buried hill trap.Tanjung formation source rocks reached the hydrocarbon generation threshold during early Miocene at a depth of 1700m, then reached the hydrocarbon generation peak during middle Miocene, oil expulsion predated the late Miocene. During the Pliocene period, Tanjung formation source rock entered the gas generation window at a depth of 3200m. During the Pliocene-Pleistocene, the Barito basin continued to uplift, Tanjung formation source rock ceased generating hydrocarbon. The traps formed earlier have been destructed, then the hydrocarbon started the second migration, in the meanwhile, the lower Warukin formation source rock reached the hydrocarbon generation threshold at a depth of 2300m.The accumulation model can be divided into three types in this paper, including the model controlled by the connected sand body pathway, the model controlled by the sand body and the fault, the model controlled together by the sand body, the fault and the unconformity. The distribution of the effective source rock, the traps, the dominant migration pathway and the direction, the preservation conditions were thought to be the key hydrocarbon accumulation controlling factors.