新疆准噶尔盆地南缘二叠系芦草沟组烃源岩生物标志化合物特征及意义

摘要

The accuracy of the evaluation result for the surface outcrop hydrocarbon source rock in the lower exploration degree area by using the traditional method is doubtful. Based on a study of such biomarkers as GC and GCMS, the authors evaluated the sedi-mentary environment, source rock kerogen type and maturity of the Permian Lucaogou Formation on the southern margin of the Junggar Basin.The Pr/Ph ratio of the hydrocarbon source rocks with an average of about 1 shows weak oxidation and weak reduction of sedimentary environments. The average value 0.15 for the gammacerane index and the high content of pregnanes indicate that the sedimentary environment was of high salinity, which was favorable for the enrichment of organic matter to a certain salinity for a weak redox sedimentary environment. The sterane C2920S(20S+20R) , C29αββ/(αββ+ααα) and C31 hopanes αβ22S/(22S+22R) values and some maturity parameter analysis show that the source rocks in the study area remain in the low mature to ma-ture stage. Emergence of tetracyclic terpane organic matter in source rocks and small regular sterane/17α(H)-hopane ratio parame-ters show that the early organic matter of the source rock was subjected to a certain degree of biodegradation.%通过地球化学分析测试技术对准噶尔盆地南缘芦草沟组烃源岩生物标志化合物特征进行研究,探讨其有机质的母质来源、沉积环境、有机质演化程度等方面的信息.芦草沟组烃源岩正构烷烃的轻碳优势和甾烷的C27-29含量关系等参数表明,母质来源主要为藻类等低等水生生物.平均1.0左右的烃源岩Pr/Ph值表明,弱氧化-弱还原的沉积环境,平均值为0.15的伽马蜡烷指数及较高含量的孕甾烷和升孕甾烷表明,沉积环境盐度较高,该沉积环境有利于有机质的富集.对甾烷的C2920S(20S+20R)和C29αββ/(αββ+ααα)值和C31藿烷αβ22S/(22S+22R)值等成熟度参数进行分析表明,研究区烃源岩处于低成熟-成熟阶段.烃源岩有机质中四环萜烷的出现及较小的规则甾烷/17α(H)-藿烷比值等参数表明,烃源岩成岩早期有机质受到一定程度的生物降解作用.