The Source Kitchen And Hydrocarbon Accumulation And Migration In The Eastern Junggar Basin

The Carboniferous in Junggar basin is deeply buried,volcanic rocks are developed,and seismic reflection conditions are poor.The distribution and development characteristics of source rocks in this area are not clear enough,and the formation process of oil and gas reservoirs is not clear enough.Taking the Carboniferous strata in Dinan uplift,Wucaiwan depression and Beisantai uplift in the east of Junggar Basin as the research object,this thesis collects data from more than 250 exploration wells in the study area,analyzes more than 2000 data of source rocks and oil and gas,discusses the organic matter abundance,organic facies types and maturity of source rocks in the study area,determines the spatial distribution of different types of source rocks,and compares them with the discovered oil and gas reservoirs,Study the law of oil and gas accumulation.A set of coal measure hydrocarbon source rock composed of mudstone,carbonaceous mudstone and coal is developed in the Carboniferous system in the east of Junggar Basin,which is mainly of F phase and partially of D/E phase.It is dominated by gas and generates a small amount of light oil and condensate.The Ro value of the hydrocarbon source rock is between 0.51%and 2.11%,and it is generally in the mature over mature stage.The carbon isotope of natural gas from Carboniferous in the east of Junggar Basin is generally heavy,with an average of-31.10‰of methane carbon isotope,-26.74‰of ethane carbon isotope,and-24.40‰of propane carbon isotope.It is mainly derived from humic organic matter.Most of the natural gas in Beisantai area meets the dry gas standard.The dry gas in Kelamei gas field is slightly more than the wet gas,while the natural gas in Wucaiwan area is all wet gas.API of crude oil from Carboniferous system is greater than 40°,carbon isotopeδThe ¹³C value is generally greater than-28‰,and the PR/PH is large,ranging from1.60 to 3.49.The hydrocarbon generating parent material of crude oil is formed in the oxidation-reduction transition environment.Through comparison with the Carboniferous C₁s^bsource rock and C₁d source rock,it is clear that the main crude oil in Ludong area comes from C₁d source rock.Carboniferous oil and gas reservoirs have the characteristics of near-source accumulation and vertical transport,and faults constitute the main drainage system in the process of oil and gas accumulation.The Carboniferous volcanic rocks are accumulated and accumulated,which belong to self-generation and self-storage oil and gas reservoirs.