The origin and source of Jurassic oil in Xihu anticline of Junggar Basin

Xihu anticline is an oil-bearing structure in Sikeshu sag located in the southern margin of Junggar Basin. Great exploration prospect can be seen for the oil and gas show up to 100 m in Qigu Formation of Jurassic. Well Xihu 1 is the first drilling layer for its deep buried depth of Jurassic layers in Xihu anticline. The whole-hydrocarbon geochemical method is used to analyze the composition and carbon isotope of natural gas, as well as the physical properties and geochemical characters of crude oil to clarify the oil origin of this area based on the analyses of source rock characters. From the results, it can be seen that main source rocks are from Jurassic and Paleogene. Crude oil in the research area has relatively heavy carbon isotopes and relatively high Pr/Ph. Regular sterane is distributed in the shape of reverse L and the ratio of gammacerane/C31 hopane value is 0.1, suggesting its origin from source rocks at mature stage.