Geochemical Characteristics and Source of Crude Oil in Shawan Depression,Junggar Basin
As an important oil and gas enrichment depression in the northwestern margin of Junggar basin,Shawan depression has significant oil and gas discoveries in Hongche fault zone and slope area.In order to clarify the source of crude oil in the structural periphery of Shawan depression,the geochemical indexes of four sets of hydrocarbon source rocks and crude oil in the northwestern margin of Junggar basin were analyzed,and the oil-source correlation was studied using the whole-hydrocarbon geochemistry.It is believed that the crude oil in Shawan depression can be divided into five types with different characteristics in biomarkers and carbon isotopes.Based on the geochemical characteristics of each set of hydrocarbon source rocks,it is considered that the Subtype A1 of crude oil in Shawan depression origins from the high matured source rocks of the Xiawuerhe Formation of Permian,the Subtype A2 of crude oil comes from the normal matured source rocks of the Xiawuerhe Formation,the Type B of crude oil derives from the intermixture of the products of the source rocks of the Fengcheng Formation and the Xiawuerhe Formation,the Type C of crude oil originates from the normal to high matured source rocks of the Fengcheng Formation of Permian,and the Type D of crude oil are the product of the Jurassic source rocks.
Shawan depressionsource rockoil-source correlationgeochemical characteristics of crude oilcarbon isotope of n-alkanes