松辽盆地梨树断陷原油高碳数三环萜烷分布特征及主控因素  

Distribution and Main Controlling Factors of High Carbon Tricyclic Terpanes in Crude Oils in the Lishu Fault Depression,Songliao Basin,China

作　　者：罗雨婷 张敏 LUO YuTing;ZHANG Min(Hubei Key Laboratory of Petroleum Geochemistry and Environment(School of Resources and Environment,Yangtze University),Wuhan 430100,China;Key Laboratory of Exploration Technologies for Oil and Gas Resources(Yangtze University),Ministry of Education,Wuhan 430100,China)

机构地区：[1]油气地球化学与环境湖北省重点实验室(长江大学资源与环境学院),武汉430100 [2]油气资源与勘探技术教育部重点实验室(长江大学),武汉430100

出　　处：《沉积学报》2023年第2期569-583,共15页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(42072165);中石油天然气集团公司科技专项(2019E2601)。

摘　　要：对梨树断陷71个湖相原油样品的饱和烃和芳烃进行了气相色谱和色谱—质谱(GC-MS)分析,根据其生物标志化合物组合特征的差异将梨树断陷的原油划分为三种类型,不同成因类型的原油样品中三环萜烷的分布特征差异明显,其中Ⅰ类原油三环萜烷的浓度明显高于Ⅱ类原油,而Ⅱ类原油Σ三环萜烷/17α(H)-藿烷比值明显高于Ⅰ类原油,但不同类型原油中均存在较高含量的高碳数三环萜烷(C28TT-C29TT),其相对百分含量均高于低碳数三环萜烷(C19TT-C20TT、C21TT、C23TT)。从沉积环境、母质来源和成熟度三方面对高碳数三环萜烷的主控因素进行了探讨,结果表明,梨树断陷不同类型原油的母质来源都是以细菌及低等水生生物为主,(C28TT-C29TT)/17α(H)-藿烷与伽马蜡烷指数有一定的正相关性,说明偏还原性的咸水环境是高碳数三环萜烷富集的次要影响因素。就该研究区而言,Σ三环萜烷/17α(H)-藿烷比值与成熟度参数Ts/(Ts+Tm)、C29-αββ/(αββ+ααα)和MDR均有良好的正相关性,表明热演化程度越高的原油越有利于高碳数三环萜烷的富集。由此可见,成熟度是梨树断陷不同类型原油高碳数三环萜烷相对丰度产生差异的主控因素。The Songliao Basin is one of the largest continental oil and gas basins in China;the Lishu Fault Depres⁃sion is a secondary tectonic unit of the Songliao Basin.In this study,71 lacustrine Lishu Fault oil samples were ana⁃lyzed for saturated hydrocarbons and aromatics.The different compositions indicated by the gas chromatography and gas chromatography-mass spectrometry(GC-MS)data indicated three types of crude oil from the Lishu Fault,each with quite different distributions of tricyclic terpanes.The absolute concentration of tricyclic terpanes in type I oil is obviously higher than in type II;however,theΣtricyclic terpanes/17α(H)-hopanes ratio in type I crude oil is signifi⁃cantly higher than in type II,but it is enriched in high carbon-number tricyclic terpane(C28TT-C29TT)compounds,with higher relative percentages than in low carbon tricyclic terpenes(C19TT-C20TT,C21TT,C23TT).The main influ⁃ences affecting high carbon number C28TT-C29TT in the Lishu Fault crude oil are discussed from three aspects:deposi⁃tion environment,organic matter source,and maturity of the crude oils.It was found that,in the organic matter sourc⁃es of the different genetic types of crude oil(mainly bacteria and low-grade aquatic organisms),the(C28TT-C29TT)/17α(H)-hopanes ratio is positively correlated with the gammacerane index,indicating that a more reductant salt wa⁃ter environment is another factor affecting the enrichment of tricyclic terpane with high carbon number.In the study area,theΣtricyclic terpanes/17α(H)-hopanes ratio is positively correlated with thermal maturity,indicating that a high degree of thermal evolution of the crude oil is more conducive to enrichment in high carbon number tricyclic ter⁃panes.It follows that thermal maturity is the main influence on the different relative abundances of high-carbon tricy⁃clic terpenes in the Lishu Fault Depression.

关 键 词：高碳数三环萜烷 主控因素 成熟度 梨树断陷 原油 

分 类 号：P618.13[天文地球—矿床学]