邛西地区邛西构造须二段气藏流体地球化学特征及连通性研究

STUDY ON GEOCHEMICAL CHARACTERISTICS OF FLUIDS AND RESERVOIR CONNECTIVITY OF XUJIAHE FORMATION IN QIONGXI GAS FIELD,SICHUAN BASIN

邛西地区邛西构造须二段的天然气因来源相同而具有相同或相似的地球化学特征,但由于天然气聚集时间上的不同,在烃类的指纹特征上仍然存在一些可检测的细微的地球化学差异。通过天然气的组分、C3—C8轻烃指纹、碳同位素单体烃组成和抽提物的分子地球化学特征综合分析,指出了不同井间流体的地球化学特征和不同井间的连通性,连通情况是:邛西构造须二段气藏整体分为连通性较差的4个区块,即构造西翼鼻突(邛西5井区)、北断垒区、南断高区和邛西12井区,其中构造北断垒区须二段气藏具有较好的内部连通性,南断高区须二段气藏内部连通也较好,二者与西翼鼻突和邛西12井区的连通性均较差。

Natural gases of the T3x^2 reservoir in Qiongxi structure have the same or similar geochemical characteristics because of the same source, but due to different time of gas accumulation, some subtle geochemical differences in the hydrocarbon fingerprint characteristics can still be detected. Based on the comprehensive analysis of gas composition, C3-C8 light hydrocarbon fingerprint, carbon isotope monomer composition and biomarkers of reservoir extract, this paper identifies the fluid geochemical characteristics of different wells and examines the reservoir connectivity. The results show that the T3x^2 reservoir consists of four poor-connectivity blocks, including uplift tectonic West Wing （Qiongxi 5 well）, horst fault block in the North, fault block in the South and Qiongxi 12 well. The North horst fault block and the fault block in the South have better internal connectivity. They are poorly connected to the uplift tectonic West Wing and the Qiongxi 12 well.