Key controlling factors for hydrocarbon accumulation on the southern margin of the Kuqa depression and prospects for hydrocarbon exploration

Abstract：The southern margin of the Kuqa depression with abundant petroleum resources and multiple reservoir-seal assemblages has great potential for petroleum exploration. Studies of trap formation, hydrocarbon generation history and organic inclusions show that there are two hydrocarbon-generating stages on the southern margin of the Kuqa depression. The first discharge of mature petroleum occurred at the end of the deposition of the Kuqa Formation (at 5 to 2 Ma BP), and the second discharge of high-maturity oil occurred from the Quaternary to present (at 2 to 0 Ma). The key factors for controlling petroleum accumulation are connection of sources by faults, good reservoir-seal assemblages, effective traps and their matching relation with hydrocarbon accumulation periods. Other factors are the tectonic evolution setting of a paleo-uplift, characteristics of formation of petroleum accumulations in multiple stages (mainly in the late stage) and favorable preservation conditions. The petroleum accumulation-forming model is the formation of petroleum accumulations in the early stage and condensate gas accumulations in the late stage. The authors propose that recent petroleum exploration should focus on Meso-Cenozoic structural traps such as the eastern Qiulitag structure with relatively intense structural deformation, anticline and fault-anticline of the Yaken gentle slope structural zone and Yangbei structural zone of the Yangxia subbasin.