北部湾盆地迈陈凹陷徐闻X3井原油地球化学特征及其成因

发布时间：2018-05-05 23:06

本文选题：生物标志化合物 + 原油　；参考：《天然气地球科学》2017年05期

【摘要】：徐闻X3井原油中出现了完整且丰富的nC_(11-39)正构烷烃系列和iC_(13-20)植烷系列与25-降藿烷系列并存现象,由此表明它是一个严重生物降解原油与正常原油的混源油。抗生物降解能力较弱的链烷烃系列和C_(14-16)二环倍半萜烷的特征可以表征晚期注入的正常原油的成因和来源。高的姥植比(Pr/Ph5.5)和明显富含陆源倍半萜烷这一特点与珠江口盆地白云凹陷和琼东南盆地所产煤成油十分吻合,表明晚期正常原油应该来源于北部湾盆地发育的涠洲组煤系烃源岩,在成因上属于煤成油。鉴于煤成油中甾烷、萜烷的浓度较湖相原油一般低1~2个数量级,其特征会被前期甾烷、萜烷浓度偏高的生物降解原油所掩盖。原油中三环萜烷系列、藿烷系列、伽马蜡烷、甾烷系列和β-胡萝卜烷及异常偏低的陆源三萜烷这一系列特征,既不同于北部湾盆地的湖相原油,也不同于相邻地区的煤成油,由此可以排除早期生物降解原油来源于盆地内发育的古近系烃源岩的可能性。鉴于北部湾盆地只有上古生界沉积有海相碳酸盐岩和碎屑岩地层,且还没有发生变质,它可以为确定徐闻X3井原油中生物降解油的来源和成因提供有用的地质和地球化学方面的信息,同时也表明北部湾盆地的上古生界沉积地层可能是值得关注的油气勘探新领域。
[Abstract]:The existence of complete and abundant n-alkane series and iCI-20) phytane series and 25-norbarane series in Xuwen X3 well crude oil shows that it is a mixture of serious biodegradable crude oil and normal crude oil. The characteristics of alkanes with weak biodegradability and C _ S _ (14-16) sesquiterpene can be used to characterize the origin and origin of normal crude oil injected in the late stage. The characteristics of high base-plant-ratio Pr-Ph5.5) and obviously rich continental sesquiterpene are in good agreement with the coal-formed oil produced in Baiyun sag of Pearl River mouth basin and Qiongdongnan basin, indicating that the late normal crude oil should come from the source rock of Weizhou formation coal series developed in Beibu Gulf basin. It belongs to coal oil in origin. Since the concentrations of steranes and terpenes in coal-derived oils are generally 1 to 2 orders of magnitude lower than those of lacustrine oils, their characteristics are masked by biodegradable oils with higher concentrations of steranes and terpenes. The series characteristics of tricyclic terpene series, cariane series, gamma wax alkane, sterane series and 尾 -carrot alkane in crude oil are different from the lacustrine oil of Beibu Gulf basin and coal-derived oil from adjacent areas. The possibility of early biodegradable crude derived from Paleogene source rocks developed in the basin can be excluded. Whereas only the Upper Paleozoic deposits in Beibu Gulf Basin contain marine carbonate and clastic strata, and no metamorphism has occurred, It can provide useful geological and geochemical information for determining the source and origin of biodegradable oil in Xuwen X3 well crude oil. It also indicates that the Upper Paleozoic sedimentary strata in Beibu Gulf Basin may be a new oil and gas exploration field worthy of attention.
【作者单位】：长江大学油气资源与勘探技术重点实验室地球化学系;中国石化江苏油田分公司地质科学研究院;
【基金】：国家自然科学基金项目(编号:41272169)资助
【分类号】：P618.13

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