准噶尔盆地东南缘西大龙口梧桐沟组—锅底坑组烃源岩地球化学特征

Geochemical Characteristics of Hydrocarbon Source Rock in Wutonggou-Guodikeng Formation of West Dalongkou,Southeast of Junggar Basin

采用饱和烃GC-MS等地球化学测试技术,通过准噶尔盆地东南缘西大龙口梧桐沟组—锅底坑组烃源岩有机质丰度、有机质类型和有机质成熟度等参数的分析,对该套烃源岩的生烃能力进行初步评价。研究表明,该套烃源岩有机质丰度中等,有机质类型为Ⅱ型、Ⅲ型;梧桐沟组—锅底坑组烃源岩中藿烷/莫烷为2.47~7.27(平均4.74),有机质演化主体已进入成熟阶段;烃源岩中Pr/Ph为0.77~1.40(平均0.96),表明沉积水体为弱氧化-弱还原环境;C_(22)/C_(21)值较低,C_(24)/C_(23)值较高,介于0.45~0.72之间(平均0.59),表明该套烃源岩为湖泊相沉积;该套烃源岩有机质来源主要为陆生高等植物,同时也有水生生物。

Using geochemical testing technology such as the method of saturated hydrocarbon GC-MS（gas chromatography-mass spectrometer）in this paper,made a preliminary evaluation of the hydrocarbon generation capacity of the hydrocarbon source rock in Wutonggou-Guodikeng formation of west Dalongkou,southeast of Junggar basin,by analyzing parameters of its organic matter abundance,type and maturity.The results show that this set of hydrocarbon source rock is of medium organic matter abundance and Type Ⅱ and Type Ⅲ organic matter.The level of hopanoic/Mo alkane is 2.47-76.32（average is 4.74）in Wutonggou-Guodikeng formation source rock,indicating that the evolution of organic matter has mainly entered the mature stage.The level of Pr/Ph in the source rock is 0.77-1.40（average is 0.96）,indicating that the sedimentary water body is in the weak oxidation-weak reduction environment.The C22/C21 value is low and C24/C23 value is high,between 0.72 and 0.45（average is 0.59）,indicating that this set of source rock is of lacustrine facies deposits.The sources of organic matter are mainly terrestrial plants as well as aquatic organisms.