Hydrocarbon Reservoir-forming Processes and Patterns in Deep Strata of Shiwu Fault Depression in the Songliao Basin

Deep reservoirs of Shiwu fault depression in the Songliao Basin experienced multi-stage hydrocarbon accumulation and multi-stage evolutions.Basin simulation of hydrocarbon generation and expulsion history of source rock and reservoir fluid inclusion analysis show three periods of reservoir forming.Primary oil-gas pools formed at the end of Denglouku period.At the end of Quantou period,many kinds of oil and gas pools formed on a large scale.Former oil-gas pools enlarged with continuous charging of hydrocarbons generating by local mature source rocks,and the former crude oils cracked into gases.At the end of Nenjiang period,primary oil and gas pools reconstructed intensively.A lot of gas pools and secondary oil-gas pools were formed in this period.Two different accumulation patterns are developed in the Shiwu fault depression.One pattern is developed in central uplift called multi-stage forming and middle-late-stage strong adjustment's type,and another pattern is developed in deep zones and slopes called early-stage forming and late-stage weak adjustment's type.