石油与天然气地质 ›› 2018, Vol. 39 ›› Issue (6): 1280-1292.doi: 10.11743/ogg20180617

• 油气勘探 • 上一篇    下一篇

渤海湾盆地渤中凹陷埕岛东坡古近系东营组二段下部源-汇系统

杨棵1,2, 董艳蕾1,2, 朱筱敏1,2, 潘荣1,2, 张梦瑜1,2, 伍炜1,2, 王珩1,2   

  1. 1. 中国石油大学(北京) 油气资源与探测国家重点实验室, 北京 102249;
    2. 中国石油大学(北京) 地球科学学院, 北京 102249
  • 收稿日期:2018-06-13 修回日期:2018-08-20 出版日期:2018-12-28 发布日期:2018-10-22
  • 通讯作者: 朱筱敏(1960-),男,教授、博士生导师,沉积学和层序地层学。E-mail:xmzhu@cup.edu.cn。 E-mail:xmzhu@cup.edu.cn
  • 作者简介:杨棵(1993-),男,硕士研究生,层序地层学与地震沉积学。E-mail:1448019312@qq.com。
  • 基金资助:
    国家自然科学基金项目(41202078)。

Analysis of the “Source-to-Sink” system in the 2nd member of the Paleogene Dongying Formation in the eastern slope of Chengdao in Bozhong Say,Bohai Bay Basin

YangKe1,2, DongYanlei1,2, Zhu Xiaomin1,2, Pan Rong1,2, Zhang Mengyu1,2, Wu Wei1,2, Wang Heng1,2   

  1. 1. State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum(Beijing), Beijing 102249, China;
    2. College of Geosciences, China University of Petroleum(Beijing), Beijing 102249, China
  • Received:2018-06-13 Revised:2018-08-20 Online:2018-12-28 Published:2018-10-22

摘要: 源汇系统是当今沉积学领域研究的热点。埕岛东坡位于渤海湾盆地,是埕北低凸起向沙南凹陷、渤中凹陷过渡的斜坡带,与埕北低凸起及其沉积区组成完整的源-汇系统。基于岩心、测井和三维地震等资料,明确物源区基岩类型、恢复东(东营组)二段古地貌格局、定量分析源-汇要素,精细刻画沉积区砂体的展布,建立研究区源-汇系统耦合模式。研究表明,研究区东二段下部主要发育的孤立洪水湖底扇沉积物均来自埕北低凸起,物源区基岩组成为碎屑岩和火山碎屑岩。砂体在沉积区的展布和规模主要受物源类型、垂向高差、汇水单元面积、搬运通道规模、坡折带、沉积区古地貌等因素影响。其中,沉积区沉积物总量与物源区垂向高差及汇水单元面积密切相关,即垂向高差大(平均垂向高差约1 280 m)、汇水单元面积大(平均汇水面积约7 km2),沉积区形成的扇体规模越大;反之,沉积扇体规模越小。此外,坡折带和沉积区古地貌也控制着扇体规模。文中划分出了地形坡折和断裂坡折两种坡折带类型,并定量统计坡折带坡角参数(最小为3.9°,最大为9.8°),数据反映坡折角度与扇体厚度和面积均呈正相关。同时,搬运通道的规模(宽深比和截面积)也影响着砂体展布。总体而言,研究区东二段沉积时期的源-汇系统配置关系较为稳定,并最终构建了多岩性源区(物源区)-古沟谷或断槽的物源通道-地形坡折/断裂坡折搬运通道(搬运区)-孤立洪水湖底扇(沉积区)-源沟坡多元耦合模式,将砂体规模与其来源形成了对应关系,为油气勘探中的砂体寻找提供了思路。

关键词: 源-汇系统, 东营组, 埕岛东坡, 济阳坳陷, 渤海湾盆地

Abstract: “Source-to-Sink” system is a hot topic in recent sedimentology research.The eastern slope of Chengdao,which constitutes a complete “Source-to-Sink” system together with Chengbei low salient and its surrounding depositional areas,is a transitional slope zone from Chengbei low salient to Shanan and Bozhong Sags,and located in Bohai Bay Basin.Based on the core,logging and 3D seismic data,we defined the basement rock types of provenance,reconstructed the palaeogeomorphology of the 2nd member of Dongying Formation(Dong 2 member),made a quantitative analysis of elements in the “Source-to-Sink” system,finely mapped the sand bodies within the depositional area,and established the coupling model of the “Source-to-Sink” system in the eastern slope of Chengdao.The results show that the isolated flood sublacustrine fan deposits,being predominant in the Dong 2 member,are all sourced from Chengbei low salient,and their basement rocks are composed mainly of clastic and pyroclastic rocks.The distribution patterns and scales of sand bodies in depositional areas are mainly controlled by source type,relief,area of catchment,size of transportation pathways,slope break zone,palaeomorphology of depositional area and so on.Among them,the total volume of sediments imputing into the depositional area is closely related to the relief and the catchment area.The larger the relief(averaging at about 1 280 m)and catchment area(averaging at around 7 km2)are,the larger the scale of the fan system will be;on the contrary,the fan system contracts accordingly.In addition,the palaeogeomorphology in the depositional area and slope break zone also exert an important control on the size of fan system.Two types of slope break zones were recognized in this study,namely the topographic and fault slope break zones.The angles of the slope break zones range between 3.9° and 9.8°,and show a positive correlation with both the fan body thickness and area.Meanwhile,the size of transportation channels(width/depth ratio and cross-sectional area)also determines the distribution characteristics of sand bodies.In summary,the elements in the “Source-to-Sink” system in the study area are relatively stable during the deposition of the study interval.Finally,we proposed a multi-factor coupling model of source areas with multiple lithologies(provenances)-channels of paleo-ravines or fault troughs within provenance-transportation pathways of topographic/fault slope break zones(transportational area)- isolated flood sublacustrine fan(sinks).This model establishes the relationship between the size of sand bodies and their provenances,and provides potential implications for predicting favorable sand bodies in future oil and gas exploration.

Key words: “Source-to-Sink” system, Dongying Formation, eastern slope of Chengdao, Jiyang Depression, Bohai Bay Basin

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