摘要
深层-超深层油气已成为新的勘探风向,越来越多的证据表明鄂尔多斯盆地中-新元古代地层的油气资源拥有巨大潜力,而沉积充填特征的研究有利于探明区域内优质烃源岩的分布,寻找良好的生-储-盖组合。本文依据盆地南缘陇东地区完整的野外露头观察结果,与研究区内钻入元古宇的探井进行岩性对比,结合清晰的地震资料,对陇东裂谷系中元古界的岩性、地震相及沉积充填序列进行分析,研究表明:1)鄂尔多斯盆地中元古代陇东裂谷系沉积充填过程主要为裂陷早期火山岩沉积、裂陷晚期陆源碎屑岩沉积及陆表海期碳酸盐岩沉积;2)明确了陇东裂谷系演化各阶段的沉积相类型:裂陷早期(Pt_(2)Ch_Ⅰ期-Pt_(2)Ch_Ⅳ期),以陆源碎屑岩(辫状河-三角洲相)与火山岩(浅湖-深湖相)为主,伴随枕状玄武岩(浅海相)发育,反映强烈伸展背景下的火山-沉积响应;裂陷晚期(Pt_(2)Ch_Ⅴ期),滨浅海石英砂岩沉积,水动力增强,物源供给充足;坳陷期(Pt_(2)Ch_Ⅵ期),沉积浅海相页岩与粉砂岩;陆表海期(Pt_(2)Jx期),沉积碳酸盐岩台地相白云岩,叠层石发育,指示稳定海侵环境。
Exploration of deep to ultra-deep oil and gas has become a new trend.Growing evidence indicates that the Meso-Neoproterozoic strata in the Ordos Basin hold significant hydrocarbon potential.The study of sedimentary filling characteristics facilitates the delineation of high-quality source rock distribution and the identification of favorable source-reservoir-cap assemblages.Based on comprehensive field outcrop observations in the Longdong area along the southern margin of the basin,this study conducts lithological comparisons with exploration wells penetrating the Proterozoic strata in the study area.Integrated with high-quality seismic data,our analysis examines the lithology,seismic facies,and sedimentary filling sequences of the Mesoproterozoic Longdong rift system.The research reveals that:1)the sedimentary filling process of the Mesoproterozoic Longdong rift system in the Ordos Basin primarily involved early rift-stage volcanic deposits,late rift-stage terrigenous clastic sediments,and epicontinental-sea-stage carbonate deposition.2)The sedimentary facies types at various evolutionary stages of the Longdong rift system were clarified:during the early rift stage(Pt_(2)Ch_Ⅰ-Pt_(2)Ch_Ⅳ),terrigenous clastic rock(braided river-delta facies)and volcanic rock(shallow to deep lacustrine facies)dominated,accompanied by well-developed pillow basalts(shallow marine facies),reflecting a volcanic-sedimentary response under intense extension;in the late rift stage(Pt_(2)Ch_Ⅴ),shallow marine quartz sandstones were deposited,indicating enhanced hydrodynamic conditions and sufficient sediment supply;during the depression stage(Pt_(2)Ch_Ⅵ),shallow marine shales and siltstones were deposited;in the epicontinental sea stage(Pt_(2)Jx),carbonate platform dolostones were formed,with well-developed stromatolites,suggesting a stable transgressive environment.
作者
成昌宇
何登发
Cheng Changyu;He Dengfa(Exploration and Development Research Institute,Zhongyuan Oilfield Company,SINOPEC,Puyang,Henan 457001;School of Energy Resources,China University of Geosciences(Beijing),Beijing 100083)
出处
《地质科学》
北大核心
2025年第6期1661-1673,共13页
Chinese Journal of Geology(Scientia Geologica Sinica)
基金
中国石油长庆油田公司科技攻关项目“鄂尔多斯盆地中元古界—奥陶系构造沉积演化、成源机制与勘探新领域”(编号:ZDZX2021-01)
国家自然科学基金企业创新发展联合基金项目“海相深层油气富集机理与关键工程技术基础研究”(编号:U19B6003)资助。
关键词
鄂尔多斯盆地
中元古界
沉积充填
Ordos Basin
Middle Proterozoic
Sedimentary filling
