Geochemical Characteristics And Source Analysis Of Crude Oil In Chunguang Block Of Chepaizi Project In Junggar Basin

Junggar Basin,as the earliest oil and gas exploration area in modern China,having complex background of hydrocarbon generation and expulsion,diverse tectonic movements and it is currently one of the most important petroleum basins in China.The Chunguang block in the study area is located on the protruding row of the second-level structural unit in the west of the Junggar Basin.Due to the influence of multi-source hydrocarbon generation and multi-tectonic superposition,the complex reservoir formation process in the study area has been complicated,and the source of crude oil has been controversial for a long time.In order to clarify the exact source of oil and gas in the Chunguang Block,the study is now based on the study of surrounding effective source rock to do comprehensive oil source comparison and more detailed classification of crude oil genetic types.And it provides strong support for oil and gas sources for future exploration and development.Using the geochemical characteristics of potential source rocks around the study area to study the organic matter abundance,type,and maturity of the source rock.On this basis,a comprehensive analysis of the characteristics of the source rocks using saturated hydrocarbon chromatography and mass spectrometry of biomarker compounds was conducted.The chromatographic characteristics of n-alkanes and the mass spectral characteristics of decane and sterane biomarkers were mainly used.Based on the results of previous studies,the source rocks were analyzed in detail.It was found that except for a small amount of aquatic organisms,the organic source of mudstones in the Badaowan Formation is mainly derived from higher-level plants of terrestrial origin and its oxidation deposition environment.The source of mudstone organic matter contained in the Sangonghe Formation is mainly from terrestrial higher plants.Algae also have a relatively large contribution,with a weak oxidative-weak reducing depositional environment.The source material of mudstone organic matter in Xishanyao Formation is mainly from terrestrial higher plants,and is a weakly oxidized to weakly reduced organic matter sedimentary environment.Permian source rocks have high abundance of ?-carrotane.The source of organic matter in source rocks is dominated by higher land-sourced plants and formed in a reducing sedimentary environment.The mudstones of the Anji Haihe Formation are dominated by algae and other aquatic organisms,and the organic matter of terrestrial higher plants also contributes a lot.The sedimentary environment is a partially reductive depositional environment.By analyzing the characteristics of crude oil geochemistry,crude oil chromatography and crude oil mass spectrometry,crude oil maturity,crude oil organic matter source,and crude oil organic matter deposition environment,the crude oil are divided into six types.Combining the geochemical characteristics of hydrocarbon source rocks and crude oil for oil source comparison.The results of the comparison show that there are both single-source crude oil and mixed-source crude oil.Type I crude oil is a single source crude oil derived from the Permian source rock in Sha wan Depression,Type II crude oil is a single-source crude oil sourced from the Jurassic source rocks in the Sikeshu sag,Type III crude oil is a single-source crude oil sourced from the Cretaceous source rock in the Shawan Depression,Type IV crude oil is derived from Permian source rocks in the Shawan Depression and Jurassic source rocks in the Sikeshu sag,mainly from the Permian source rocks.The V crude oil is derived from Permian source rocks,Cretaceous source rocks,and Jurassic source rocks in the Sikeshu sag of Shawan Depression and crude oil from Jurassic source rocks is mainly,The VI crude oil is derived from the source rocks of the Jurassic source rocks and the Anjihaihe Formation source rocks in the Sikeshu sag,and is mainly sourced from the Anji Haihe formation.