鄂尔多斯盆地甘泉地区延长组长8段原油地球化学特征及来源  

Geochemical Characteristics and Source of Crude Oil in Chang 8 Member of Yanchang Formation, Ganquan Area, Ordos Basin

作　　者：朱必清 陈世加[1,2] 白艳军[3] 雷俊杰 尹相东[1,2] ZHU Biqing;CHEN Shijia;BAI Yanjun;LEI Junjie;YIN Xiangdong(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu,Sichuan 610500,China;School of Geosciences and Technology,Southwest Petroleum University,Chengdu,Sichuan 610500,China;Yanchang Oil Field Co.,Ltd.,Xi'an,Shaanxi 710000,China)

机构地区：[1]油气藏地质及开发工程国家重点实验室,西南石油大学,四川成都610500 [2]西南石油大学地球科学与技术学院,四川成都610500 [3]延长油田股份有限公司,陕西西安710000

出　　处：《现代地质》2022年第2期742-754,共13页Geoscience

基　　金：国家自然科学基金项目(41872165,42002176);中国石油-西南石油大学创新联合体科技合作项目(2020CX030000,2020CX050000)。

摘　　要：通过系统采集鄂尔多斯盆地东南部甘泉地区原油、砂岩和烃源岩样品,分析了延长组长8段原油地球化学特征,明确了原油成因和来源。研究表明:长8段原油为正常原油,具有低黏度、低初馏点、低凝点和低含硫量的特征;生物来源为混合型输入,形成于弱氧化-弱还原环境,是生油高峰阶段的产物。根据C_(30)重排藿烷和二环倍半萜类分布特征可将原油分为Ⅰ类和Ⅱ类原油,Ⅰ类原油主要分布于长8_(1)段,Ⅱ类原油主要分布于长8_(2)段。长9段和长8段烃源岩具低C_(24)TeT/C_(26)TT、高-异常高C_(30)重排藿烷含量、低8β(H)升补身烷和8β(H)补身烷含量的特征,长7段烃源岩与之相反。油源对比结果表明,Ⅰ类原油为长7烃源岩贡献,Ⅱ类原油为长8和长9段烃源岩贡献。甘泉地区主要发育长8_(2)油藏,其西部原油为长8和长9烃源岩贡献,而东部原油主要为长9烃源岩贡献,长7烃源岩次之。研究认识到长8和长9烃源岩的烃类贡献可能是促使长8_(2)段较长8_(1)段富集的重要因素,对下步勘探有指导意义。Through systematic collection of crude oil,sandstone and source rock samples from Ganquan in the southeastern Ordos Basin,the geochemical characteristics of Chang 8 crude oil in Yanchang Formation were characterized,and the origin and source of the crude oil clarified.We show that Chang 8 crude oil is the normal crude oil featured by low viscosity,initial boiling point,pour point and sulfur content.The Chang 8 crude oil have mixed organic matter sources,which were formed in a weakly reducing environment during the peak oil generation stage.According to the distribution characteristics of C_(30)DiaH and dicyclic sesquiterpenes,the crude oils can be divided into type I and II:Type I crude oil is mainly distributed in Chang 8_(1) reservoir,and type II crude oil is distributed in Chang 8_(2) reservoir.The Chang 9 and Chang 8 source rocks are featured by low C_(24)TeT/C_(26)TT,abnormally high C_(30)DiaH,high 8β(H)-homodrimane and 8β(H)-drimane,while Chang 7 source rock show the opposite features.Oil-source correlation shows that type I crude oil was sourced from Chang 7 source rock,whilst type II crude oil was sourced from Chang 8 and Chang 9 source rocks.The crude oils in Ganquan are mainly enriched in Chang 8_(2) member,and Chang 8_(2) reservoir in western Ganquan was contributed by Chang 8 and Chang 9 source rocks,while Chang 8_(2) reservoir in eastern Ganquan was mainly contributed by Chang 9(and minor Chang 7)source rocks.We recognize that the hydrocarbon contribution of the Chang 8 and Chang 9 source rocks may have been key to the crude oil enrichment in the Chang 8_(2) member,which has guiding significance for future exploration.

关 键 词：鄂尔多斯盆地 甘泉地区 长8段原油 原油地球化学特征 油源对比 

分 类 号：TE122.1[石油与天然气工程—油气勘探]