古地理学报2024，Vol.26Issue(4)：816-833,18.DOI:10.7605/gdlxb.2024.04.050
断陷湖盆陡坡带早期斜向扇三角洲形成机制、发育规律及勘探启示:以东营凹陷北带为例
Formation mechanism,development regularity and exploration implica-tion of oblique fan delta in steep slope zone of rift lacustrine basin in the early stage of rifting:a case from northern belt of Dongying sag
摘要
Abstract
As one of the most important types of oil and gas basins in the world,the rift lacustrine basin can often form glutenite sedimentary formations with a thickness of thousands of meters in the early stage of filling and evolution process,which has become an important field of oil and gas exploration.However,there are still many controversies regarding the sedimentary genesis of this extremely thick glu-tenite.In this study,Yanjia area in the steep slope zone of the Dongying sag,a typical rift lacustrine ba-sin in Jiyang Depression,is selected as an example.Utilizing high-resolution 3D seismic data,core sam-ples,logging,and well logging,we conduct a systematic analysis of the glutenite sedimentary formations in the steep slope zone during the early rifting stage.This study applies seismic stratigraphy,structural geology,sedimentology,and rheology analysis methods comprehensively.The following understandings have been obtained:(1)The gravel content in the sediments of oblique fan delta is relatively high,which is formed by traction flow and gravity flow.The average quartz content is about 40％-55％.Fan delta plain,fan delta front and pre-fan delta subfacies are developed.The seismic response characteristics in-clude(oblique,imbricate and broom-shaped)progradation facies along the direction of sediment source,and filling facies perpendicular to the sediment source direction.(2)The oblique fan delta mainly deve-loped in the early stage of rifting,and disappeared in the middle stage of rifting.The fan and the boundary fault are obliquely intersected at a low angle,typically not exceeding than 45°.The development scale of the fan is affected by the location of its root,and its disappearance is not isochronous.(3)A new mecha-nism for the formation of the large-scale oblique fan delta in the steep slope zone of the rift lacustrine basin during the early stage of rifting is proposed.Relay structures related to the segmentation characteristics of boundary faults provide transport conduits for the development of oblique fan deltas.The paleo-troughs con-trolled by the boundary fault activity provide new accommodation for the development of oblique fan deltas during the early stage of rifting.The fracture zone formed by the interaction between faulted blocks provide material basis for the development of oblique fan deltas,and the connection of the faulted block leads to the disappearance of the oblique fan delta and the transformation to the nearshore subaqueous fan.(4)It has been found that most of the deep glutenite reservoirs in the steep slope zone of the rift lacustrine basin belong to the oblique fan deltas.This study points out that the relay zones at all levels in the steep slope zone can be key target areas for exploration,and the well layout direction follow the oblique boundary fault.This study not only enriches the sedimentary theory of steep slope zone in rift lacustrine basin,but also provided a new idea and theoretical basis for deep petroleum exploration of the continental rift lacus-trine basin in China.关键词
断陷湖盆陡坡带/斜向扇三角洲/演化/展布特征/深层油气/东营凹陷Key words
steep slope zone of rift lacustrine basin/oblique fan delta/evolutionary/distribution feature/deep petroleum exploration/Dongying sag分类
天文与地球科学引用本文复制引用
李晋,肖洪,刘震,张忠民,刘建平,孙笑凡,刘惠民,杨光,朱茂林,王文彬..断陷湖盆陡坡带早期斜向扇三角洲形成机制、发育规律及勘探启示:以东营凹陷北带为例[J].古地理学报,2024,26(4):816-833,18.基金项目
国家自然科学基金青年科学基金项目(编号:42302185)和中国博士后科学基金面上项目(编号:2023M743884)联合资助.[Co-funded by the Young Scientists Fund of the National Natural Science Foundation of China(No.42302185)and the China Postdoctoral Science Founda-tion(No.2023M743884)] （编号:42302185）
