煤系烃源岩中四种类型高丰度重排藿烷组成特征及成因探讨——以鄂尔多斯盆地上古生界为例  

Composition Characteristics and Genesis of Four Types of High-Abundance Rearranged Hopanes in Coal Measure Source Rocks:A case study of Upper Paleozoic strata in the Ordos Basin

作　　者：张文俊 林舒敏 柯行 张敏 ZHANG WenJun;LIN ShuMin;KE Xing;ZHANG Min(Hubei Key Laboratory of Petroleum Geochemistry and Environment(School of Resources and Environment,Yangtze University),Wuhan 430100,China;Tianjin Branch of CNOOC Ltd,Tianjin 300459,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]中海石油(中国)有限公司天津分公司,天津300459

出　　处：《沉积学报》2025年第2期683-700,共18页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(42072165,41272170)。

摘　　要：【目的】探讨煤系烃源岩中四种类型高—异常高丰度重排藿烷的分布模式、组成特征及主控因素。【方法】利用色谱—质谱(GC-MS)分析技术,对鄂尔多斯盆地上古生界29个煤系烃源岩饱和烃和芳烃进行了详细剖析。【结果】检测到四种类型的重排藿烷,它们是17α(H)-重排藿烷系列(C_(30)^(*))、18α(H)-新藿烷系列(Ts和C_(29)Ts)、早洗脱重排藿烷系列(C_(30)E)和28,30-二降-21-甲基重排藿烷系列(29Nsp)。研究表明同一类型重排藿烷类化合物之间表现出良好的相关性;不同类型重排藿烷类化合物之间相关性有所不同,表现为C_(30)^(*)/C_(30)藿烷(C_(30)H)、C_(30)E/C_(30)H、29Nsp/C_(29)H这三者之间的相关性较好,C_(29)Ts/C_(29)H与上述三者的相关性均较差,说明不同类型重排藿烷类化合物形成机理可能有所差别。随着有机质热演化程度的增加,C_(30)^(*)、C_(30)E和29Nsp重排藿烷类化合物相对丰度呈现出近似正态分布,在生油高峰阶段(Ro为0.80%~0.90%),高—异常高重排藿烷类化合物相对丰度达到峰值。除此之外,具有高—异常高丰度藿烷样品的(C28+C_(29))三环萜烷(TT)/C_(30)H和规则甾烷/C_(30-35)H的比值与重排藿烷跟同碳数藿烷的比值(C_(30)^(*)/C_(30)H、C_(30)E/C_(30)H、29Nsp/C_(29)H)均具有明显的正相关性,揭示高—异常高重排藿烷类化合物的生源母质主要为低等水生生物和菌藻类化合物。【结论】通过同一类型重排藿烷类化合物具有相同演化路径与形成机制,推测煤系烃源岩中具有高—异常高丰度的17α(H)-重排藿烷、早洗脱重排藿烷、28,30-二降-21-甲基重排藿烷形成于Pr/Ph介于1.00~2.00,伽马蜡烷指数介于0.10~0.13的沉积环境,且生物前身物主要为细菌藿烷类化合物;而高—异常高丰度18α(H)-新藿烷的形成主要受控于有机质的生源母质,其生源母质可能为里白烯或C_(29)藿烷类化合物。[Objective]We explored the distribution pattern,composition characteristics,and main controlling factors of four types of high-abnormally high abundant rearranged hopanes in coal measure source rocks in the Ordos Basin.[Methods]The saturated hydrocarbons and aromatic hydrocarbons of 29 coal measure source rocks in the Upper Paleozoic of the Ordos Basin were analyzed in detail using gas chromatography-mass spectrometry(GC-MS).[Results]Based on the peak order and retention time of the compounds,GC-MS analysis of the coal measure source rocks in Ordos Basin was conducted.Four types of rearranged hopanes with different abundances were systematically identified:17α(H)-rearranged hopane series(C_(30)^(*)),18α(H)-neohopane series(Ts and C_(29)Ts),early-eluting rearranged hopane series(C_(30)E),and 28,30-dinor-21-methyl rearranged hopane series(29Nsp).The peak order of the four types of rearranged hopane compounds is:early-eluting rearranged hopane series>17α(H)-rearranged hopane series>18α(H)-neohopane series>28,30-dinor-21-methyl rearranged hopane series(29Nsp).The study of the internal composition of these four types of rearranged hopane compounds in the coal measure source rocks in the study area shows good correlation between the same types of rearranged hopane compounds;that is,there is a good correlation between C_(30)^(*)/C_(30) hopane and C_(29)*/C_(29) hopane,C_(29)Ts/C_(29) hopane and Ts/Tm.The correlation between different types of rearranged hopanes is different.The correlation between C_(30)^(*)/C_(30) hopane,C_(30)E/C_(30) hopane and 29Nsp/C_(29) hopane is good,but the correlation between C_(29)Ts/C_(29) hopane and the other three is poor,indicating that the formation mechanism of different types of rearranged hopanes may differ.In addition,the relative abundance of 17α(H)-diahopane series,early elution diahopane series,and 28,30-dinor-21-methyldiahopane series(29Nsp)in the coal measure source rock samples is significantly affected by water redox and salinity conditions.With the increase of thermal ev

关 键 词：重排藿烷 主控因素 沉积环境 煤系烃源岩 鄂尔多斯盆地 

分 类 号：P618.13[天文地球—矿床学]