第37卷第6期 2016年12月
文章编号：10013873(2016)06-065406
新疆石油地质
XINJIANG PETROLEUMGEOLOGY D0I:10.7657/XJPG20160605
Vol.37,No.6 Dec.2016
异常热作用对原油正构烷烃碳同位素特征的影响
一以塔里木盆地为例
李迪"，郑朝阳"，王字？，周文喜"苏劲”，蔡郁文
（1.贵州大学资源与环境工程学院，贵阳550025;2.中国石油勘探开发研究院石油地质实验研究中心，北京100083）摘要：原油正构烷烃碳同位素曲线特征分析是油-油、油-源对比的重要手段，研究发现，正构烷烃碳同位素曲线会受多种次生作用的改造而改变原始面貌。二叠纪发生的地慢柱事件不仅改造了塔里木盆地早期油气的储集条件，伴随的异常热作用对油气的地球化学特征和物理-化学性质也产生了较大影响。通过导找TZ421井、TD2井、ZS1(ZS1c)并、TZ62井等受异常热作用改造的证据以及分析其原油正构烷烃碳同位素曲线的变化，发现原油正构烷烃碳同位素曲线特征记录了塔里木盆地存在的多种类型的异常热事件，反映了原油原始碳同位素特征经历的改造。通过分析异常热作用改造的正构烷烃碳同位素曲线特征，将其划分为3种类型，分别反映了热液和岩浆热作用、硫酸盐热化学还原反应以及热蚀变作用对正构烷烃碳同位素特征产生的差异性改造，揭示了不同类型异常热作用对正构烷烃单体碳同位素分馏的影响。正构烷烃碳同位素曲线特征在作为塔里木海相原油端元油划分的依据时还需谨慎考虑。关键调：塔里木盆地；正构烷烃；碳同位素；异常热作用；油-源对比；地慢柱；次生改造作用
中图分类号：TE112.113
文献标识码：A
InfluenceofAbnormalThermalEffectonCarbonIsotopeCharacteristicsofN-Alkanesin
CrudeOil:ACasefromTarimBasin
LI Di',ZHENG Zhaoyang',WANG Yu',ZHOU Wenxi',SU Jin",CAI Yuwen
(1.School of Resources and Environment Engineering, Guizhou University, Guiyang, Guizhou 550003, China; 2.Experimental Research Center of Petroleum Geology, Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China)
Abstract: Analysis on n-alkane carbon isotope curves of oil is an important method for oil-oil and oil-source correlation. The study shows that n-alkane carbon isotope curves tend to be changed due to several secondary actions, Mantle plume event in Permian reformed the oil accumulation conditions, meanwhile the associated abnormal thermal effect brought significant influences to geochemical features and physical-chemical properties of the oil in Tarim basin. Based on the evidences of abnormal thermal effect in Well TZ421, TD2, ZS1(ZS1c) and TZ62 and the analysis of the changes of n-alkane carbon isotope curves of the oil in these wells, it is found that the curves record vari-ous abnormal thermal events occurred in Tarim basin and could reflect the reformation of the original carbon isotope characteristics of oil. Through the analysis on the changed n-alkane carbon isotope characteristics caused by abnormal thermal effects, 3 characteristics can be identified, which reflects their differential reformations caused by thermal effects of hydrothermal solution and magma, sulfate thermochemi-cal reduction reaction and thermal alteration, respectively, and reveals the influences of different thermal effects on n-alkane free-carbon isotope fractionation. Using n-alkane carbon isotope characteristics as the basis for marine end-member oil division should be carefully con-sidered in Tarim basin.
Keywords: Tarim basin; n-alkane; carbon isotope; abnomal thermal effect; oil-source correlation; mantle plume; secondary reformation
原油中的正构烷烃能够在很大程度上反映原油的演化特征。早在20世纪90年代初，文献[1]就将原油中有机分子化合物的碳同位素组成特征应用于油一源对比研究，正构烷烃的碳同位素特征可用于鉴别混合油-,区分"煤成油"或“非煤成油"。文献[5]利用正构烷烃的单体碳、氢同位素特征进行较高成熟度原油的油-源对比，推断生烃母质的古环境特征。原油正构烷烃的碳同位素特征会因原油经历的后期改造而发生明显变化，其中生物降解作用的影响较为明
收稿日期：2016-05-05
修订日期：2016-06-30
显，因此，正构烷烃单体碳同位素曲线特征仅适用于对生物降解程度较低的原油进行油-源对比。正构烷烃碳同位素特征随裂解程度发生改变，可以反映出原油的裂解程度"。因此发生过裂解的原油不能单纯的通过曲线形态对比来寻找油-油、油-源之间的联系。文献[8]通过沥青砂中沥青干馏物的正构烷烃碳同位素特征，推测出生物降解后的古油藏发生了二次充注，并判断出油源。文献[9]以正构烷烃碳同位素曲线特征作为依据划分的塔里木盆地寒武系端元油
基金项目：国家自然科学基金（41273062)；国家科技重大专项（2008ZX05007-001）
作者简介：李迪（1989-），男，新疆乌鲁木齐人，硕士研究生，油气地球化学，（Tel)18096193807(E-mail)lidi009@126.com 万方数据