叶城凹陷柯东1井凝析油及柯克亚原油的油源分析

塔里木盆地叶城凹陷拥有多套烃源岩层，主要为石炭系卡拉乌依组、二叠系棋盘组与普司格组2-3段、侏罗系煤系地层与叶尔羌群等，这些烃源岩都可能是柯东1井凝析油和柯克亚第三系原油的母源。在这一地区，油源一直是一个很具争议性的问题。选取了叶城凹陷克里阳构造带柯东1井2个凝析油、柯克亚构造带7个第三系原油，以及叶城凹陷各烃源岩层具有代表性的17个烃源岩样品，对其生物标志物及正构烷烃单体烃稳定碳同位素比值等参数进行了详细的测试分析。油油对比揭示，柯东1井原油与柯克亚第三系原油在正构烷烃组分、成熟度与稳定碳同位素组成等特征上具有明显的相似性，显示同源的特征。油源对比显示，普司格组2-3段下部是这些原油的源岩。这一烃源岩层具有与柯克亚地区原油一致的成熟度和相似的特征性生物标志物，即高含量的重排藿烷、Ts和 C27-C29重排甾烷等，而其他烃源岩层则不具备这类特征。较高成熟阶段形成的原油，解释了普司格组2-3段烃源岩可溶有机质与柯东1井等原油在单体烃稳定碳同位素比值上具有2‰~3‰的差别。

Oil source of condensates from Well Kedong 1 and crude oil from Kekeya in Yecheng depression

Yecheng depression in Tarim Basin developed several layers of source rocks, including Carboniferous Kalawuyi formation, Permian Qipan formation and Pusige formation 2-3 parts, Jurassic Yarkant formation and coal measure strata. These source rocks may be the origin of condensates from Well Kedong 1 and crude oil from Kekeya Tertiary strata. The origin of crude oil in this area has been controversial for a long time. We selected 2 condensate samples from Well Kedong 1,7 Tertiary crude oil samples from Keliyang tectonic belt of Yecheng depression, 17 representative source rock samples, and finished a series of measuring-analysis work on geochemistry parameters of these samples, such as biomarkers and individual hydrocarbon isotopic composition ratio. Oil-oil correlation shows that condensates from Well Kedong 1 and Kekeya Tertiary strata have much in common in n-alkanes component, maturity and stable carbon isotope, indicating their same-origin characteristics. Oil-source correlation shows that source rocks from underpart of 2-3 sections of Pusige formation may be origin of crude oil in the research area. Pusige formation source rock strata and crude oil from Kekeya area have the same maturity and similar characteristic biomarkers, that is high content of C30 rearrangement hopane, Ts, C27-C29 diasteranes, etc, while other source rocks strata don’t have this feature. The crude oil’s high maturity may explain＆amp;nbsp;why there is a 2‰-3‰ difference in stable carbon isotope ratio between condensates from Well Kedong 1 and soluble organic matters from Pusige formation 2-3 section’s underpart source rocks.