OIL & GAS ACCUMULATION CONDITIONS AND MODELS IN THE TRIASSIC CLASOLITES OF YUQI BLOCK IN AKEKULE ARCH,TARIM BASIN

Yuqi block in the north of the Akekule arch,Tarim basin is an important oil gas exploration area in the Tahe Oilfield.Under the guidance of the theories of basin evolution,hydrocarbon generation,and oil gas accumulation,the oil gas accumulating conditions in the clasolites of the Triassic Akekule and Halahatang formations in the Yuqi block were discussed,and oil gas accumulation models were established according to the techniques of basin analysis,reservoir prediction,fluorescence thin section and fluid inclusion.The result shows that the oil gas in the Yuqi block was derived from the Cambrian to lower Ordovician source rocks in the south of the Akekule arch;and the Akekule and Halahatang formations in the Yuqi block has definite resources potential.The clasolites reservoirs types are porosity,with high porosity,and permeability ranging from intermediate to high.The favorable reservoirs is located in the wells of YQ3,YQ4,LX4 and LX2.The mudstone as seal rock in the Triassic Akekule and Halahatang formations is valid.The profitable preservation region is located in the south of the Yuqi block.The trap types are low scope tectonic traps and lithological traps.The oil gas distribution is controlled by faults and low scope anticlines.There are three times of oil/gas charges,i.e.,Yanshanian,early Himalayan and late Himalayan.The oil gas accumulation model in the Yuqi block is outward source-bidirectional hydrocarbon expulsion multi-stage accumulation or hydrocarbon sourced from the old rocks and preserved in the young rocks-bidirectional hydrocarbon expulsion-multistage accumulation with two-stage evolution.This model will provide a theoretical fundament for the next exploration in the Yuqi block and its vicinities.