渤南洼陷沙四段膏泥岩中高丰度孕甾烷成因及其指示意义  

Origin and significance of high pregnane abundance in gypsum mudstone in the Fourth member of the Shahejie Formation in Bonan Sag,Jiyang Depression

作　　者：雷春生 杜振京 卢鸿[1] LEI Chunsheng;DU Zhenjing;LU Hong(State Key Laboratory of Organic Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;CAS Center for Excellence in Deep Earth Science,Guangzhou 510640,Guangdong,China;University of Chinese Academy of Sciences,Beijing 100049,China;College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China;Management Center of Oil and Gas Exploration,Shengli Oilfield Company,SINOPEC,Dongying 257000,Shandong,China)

机构地区：[1]中国科学院广州地球化学研究所,有机地球化学国家重点实验室,广东广州510640 [2]中国科学院深地科学卓越创新中心,广东广州510640 [3]中国科学院大学,北京100049 [4]中国石油大学(北京)地球科学学院,北京102249 [5]中国石化胜利油田油气勘探管理中心,山东东营257000

出　　处：《地球化学》2024年第2期183-194,共12页Geochimica

基　　金：国家重点研发计划“深地资源勘查开采”重点专项(2017YFC0603102);国家自然科学基金项目(41973069)联合资助

摘　　要：渤南洼陷沙四段膏泥岩样品中检出了高丰度孕甾烷(相对于规则甾烷),孕甾烷/规则甾烷值为0.52~7.88,平均值为3.12。这些膏泥岩样品具有指示性较强的盐湖相生物标志化合物分布特征,如较低的姥鲛烷/植烷值(Pr/Ph=0.12~0.76)、高伽马蜡烷指数(GI=0.04~1.45)、高升藿烷指数(HHI=0.03~0.22)和较高的二苯并噻吩/菲值(DBT/P多大于1),均指示了高盐度水体、强还原性和富硫沉积环境,生源输入主要为嗜盐菌和藻类等低等水生生物。根据渤南洼陷沙四段原油中检出丰富的含硫甾烷,推测渤南洼陷高丰度孕甾烷可能与含硫甾烷形成过程中的不完全硫化作用有关。通过剖面上各生物标志化合物参数随埋深的纵向变化特征发现,孕甾烷与Pr/Ph、HHI和GI值等呈现良好的相关性,它们均指示还原、高盐度以及富硫贫铁的沉积环境。High abundance of pregnane relative to regular sterane was determined in gypsum mudstone samples from the Fourth member of the Shahejie Formation in the Bonan Sag,Jiyang Depression.The ratios of pregnane and homopregnane relative to regular steranes ranged from 0.52 to 7.88,with an average of 3.12.The gypsum mudstone samples showed unique biomarker characteristics,such as low ratios of pristane/phytane(0.12 to 0.76),high gammacerane index(0.04 to 1.45),high homohopane index(0.03 to 0.22),and high ratio of DBT/P(dibenzothiophene/phenanthrene,mostly lager than 1.0).These biomarker ratio assemblages indicate the presence of stable oxic-anoxic stratification in the water column,sulfur-rich conditions,and blooms of heterotrophic bacteria.However,the causes of the high abundance of pregnane remain unresolved.Based on the abundant sulfur-containing steranes detected in the crude oils of the 4th member of the Shahejie Formation in the Bonan Sag,it is speculated that the high abundance of pregnane in the Bonan Sag may be related to the incomplete sulfurization during the formation of sulfur-containing steranes.The variation of biomarker parameters rations with the burial depth was analyzed,and the results showed that pregnane has a good correlation with other biomarker parameters,such as the ratio of pristane/phytane,the homohopane index,and the gammacerane index.These parameters can be combined and used as indicators of reduction,hypersaline,iron-poor,and sulfur-rich environments.

关 键 词：渤南洼陷 膏泥岩 孕甾烷 含硫甾烷 

分 类 号：P593[天文地球—地球化学]