塔里木盆地顺北地区深部油藏轻烃地球化学特征及其指示意义  

Molecular carbon isotopic compositions of light hydrocarbons in crude oils from deep buried reservoirs in the Shunbei area,Tarim Basin,and implications for oil genetic types

作　　者：孔丽姝 路清华 何毓新 顾忆[2] 孙永革[1] KONG Li-shu;LU Qing-hua;HE Yu-xin;GU Yi;SUN Yong-ge(Organic Geochemistry Unit,School of Earth Sciences,Zhejiang University,Hangzhou 310027,China;Wuxi Institute of Petroleum Geology,Petroleum Exploration and Production Research Institute,SINOPEC,Wuxi 214126,China)

机构地区：[1]浙江大学地球科学学院有机地球化学研究组,浙江杭州310027 [2]中国石油化工集团公司石油勘探开发研究院无锡石油地质研究所,江苏无锡214126

出　　处：《地球化学》2021年第3期261-272,共12页Geochimica

基　　金：国家自然科学基金(42030803)。

摘　　要：深部高温高压环境下原油的成因类型判识一直是深部油气勘探评价中的关键问题之一。塔里木盆地顺北地区7300~8000 m埋深奥陶系鹰山组以及一间房组轻质油藏的发现为研究其成因提供了一个很好的契机。本研究以原油轻烃及其分子稳定碳同位素地球化学组成为基础,系统探讨了塔里木盆地顺北地区深层原油成因特征。研究结果表明,顺北深层原油热演化程度高,为轻质油-凝析油阶段成烃产物。通过与邻区典型油藏热裂解成因原油对比,揭示顺北深层原油总体未受或经历轻微热改造影响,但不同井区存在一定差异性。顺北1井区(SB1井区)、顺北2井(SB2井)和顺北5井区(SB5井区)原油属于正常干酪根热降解成烃产物,未受显著热改造作用影响;顺北3井(SB3井)原油可能受轻微热改造作用影响;顺北7井(SB7井)原油高的姥植比、甲基环己烷重碳同位素、低的芳构化特征,指示可能具有特殊的成烃来源或成藏改造过程。Assessment of oil genetic types in deep buried reservoirs,which are under high temperature and pressure,has been one of the main challenges in deep petroleum exploration.Ordovician oils,found at a depth of 7300–8000 m in the Yingshan Formation and the Yijianfang Formation in the Shunbei area of the Tarim Basin in northwest China,provide an opportunity to probe the genetic types within a geochemical background.We systematically examined the compositions of the light hydrocarbons and the stable carbon isotopes of individual compounds in the crude oils from the Shunbei area.The results showed that the deep-buried oils were light oils and condensates,and had experienced high thermal maturation.We showed that the crude oils in the Shunbei area were either not affected or slightly affected by thermal alteration,in comparison with thermal cracking oils in adjacent areas.However,there were differences among the crude oils from the Shunbei area.The crude oils from the Shunbei 1,Shunbei 2,and Shunbei 5 Wells were kerogen thermally degraded products,whereas the oil from the Shunbei 3 Well probably experienced slight thermal alteration.As indicated by a relatively high pristane/phytane ratio,heavy carbon isotopic compositions of methylcyclohexane,and low aromatization characteristics,the crude oils from the Shunbei 7 Well might be from a special source and/or have experienced secondary alterations.

关 键 词：轻烃分子碳同位素 深部油藏 原油热裂解 顺托果勒 塔里木盆地 

分 类 号：P593[天文地球—地球化学] TE122[天文地球—地质学]