Research On Hydrocarbon Accumulation Law Of Jurassic In Eastern Hanshan Area

The oil-gas exploration in eastern Hala'alate Mountain,located on the northern border of Junggar Basin,is restricted by undefined hydrocarbon migration and accumulation law.The hydrocarbon transporting ability of faults,unconformity and sandstone in the studied area was evaluated based on the comprehensive analysis of drilling,core and seismic data.The result shows that oil in Jurassic is from Permian in Mahu depression,which means a huge distance between source rock and reservoirs.Therefore,passage system plays a critical role in the formation of oil reservoir.With the analysis of unconformity structure,it's found out that the unconformity doesn't have long transportation ability.Major faults in Wuxia fault belt are the oil-source faults,which are the vertical migration passage of hydrocarbon from bottom to top.The sandstones in the Badaowan Formation and Xishanyao Formation with high porosity,permeability and good lateral connectivity are the lateral migration passage.The effective fault-carpet passage system composed by oil-source faults and sandbodies plays a crucial role in the hydrocarbon migration and accumulation.Positive structures such as nose structure and tectonic ridges control the main migration direction of hydrocarbon,which has the ability to converge hydrocarbon obviously.The horizons cut by source-related faults and fault sealing property control the vertical distribution of hydrocarbon,and the accommodation faults in the shallow control the hydrocarbon migration in carpet sand and the hydrocarbon accumulation in sand above carpet.Lots of developing stratigraphic traps form large stratigraphic reservoirs,while lithological and structural-lithological reservoirs above carpet sand are barely developed.The hydrocarbon accumulation is controlled by the plane distribution of carpet sand and the lithology,physicalcharacteristics and pore structures of reservoirs in different systems.So it's figured out that the up-dip sandstone pinchout and isolated sand which is linked with secondary order fault are the most favorable exploration targets.