渤海湾盆地东营凹陷始新世三角洲供给型重力流地震沉积学研究  

Seismic sedimentology of delta-fed turbidites of the Eocene in Dongying sag,Bohai Bay Basin

作　　者：刘建平[1] 鲜本忠[1,2] 王璐[1,3] 路智勇[4] 李宇志[4] 刘赛君[1] 蒋健[1] 

机构地区：[1]中国石油大学(北京)地球科学学院,北京102249 [2]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 [3]中国石油集团测井有限公司长庆事业部,陕西西安710201 [4]中国石化胜利油田东辛采油厂,山东东营207015

出　　处：《古地理学报》2016年第6期961-975,共15页Journal of Palaeogeography：Chinese Edition

基　　金：国家自然科学基金项目(编号:41172104;41272133;41372117);国家科技重大专项(编号:2011ZX05009-002;2011ZX05014-001)联合资助~~

摘　　要：陆相盆地三角洲前端滑塌型重力流砂岩因富含油气而广受关注,其厚度薄、面积较小、期次多,储集层预测难度大,长期以来制约了油气的精细勘探开发。利用全覆盖三维地震资料和已有钻孔信息,对东营凹陷东辛地区始新世三角洲—重力流沉积体系开展了以层序地层学和沉积学研究为基础的地震沉积学研究。研究表明,沙三中亚段对应二级基准面下降背景的三级层序,以6期大规模高位域三角洲(第5准层序组—第10准层序组)的发育为特征。以第8准层序组为例,以四级层序为研究单元落实了来自不同物源的3个三角洲—重力流沉积体系;再根据地层切片进一步分期落实了其内部薄砂岩储集层的空间分布。地层接触关系特殊,地层厚度和岩性的横向变化剧烈,导致三角洲—重力流发育区地震波速纵横向变化较大。基于目的层精细标定的相位调整成为地震沉积学研究的基础,四级层序(而不是体系域或层序)的约束成为保障地层切片等时性的关键。研究结果表明,四级层序约束下的地震沉积学研究,为三角洲前端滑塌型重力流薄砂岩储集层的横向预测提供了有效的技术支撑,也为恢复深水重力流发育区沉积过程、深化重力流沉积规律奠定了基础。Gravity-flow sandstones fed by sediment slumping on the delta front in lacustrine basin is widely concerned due to their huge oil-gas exploration potential. Lacustrine turbidite reservoirs with small thickness,small scale and multi-layer limited the fine hydrocarbon exploration and development of gravityflow deposits. Based on studies of sequence stratigraphy,sedimentology,drilling and logging data,and full-covered 3D seismic data,seismic sedimentology of the Eocene delta-turbidite sedimentary system was studied in Dongxin area,Dongying sag. The research shows that the middle sub-member of Member 3 of Shahejie Formation corresponds to a 3rd order sequence that formed under declining base level,and the highstand system tract is characterized by six phases of delta progradations（ parasequence sets 5 to parasequence sets 10）. According to a case study from parasequence sets 8,three delta-turbidite sedimentary systems from different provenances were confirmed within the 4th order sequence,and the distribution of thin sandstone were identified by strata slices. Seismic velocity heterogeneity in delta-turbidite areas is resulted from particular strstigraphic contact and sharply lateral changes in strata thickness and lithology.Phase adjustment after fine well-seismic calibrating for the target reservoir is the foundation of seismic sedimentology in delta-turbidite system, and restriction from the 4th order sequence（ rather than systems tracts or the 3rd sequence boundaries） is the key of ensuring the isochronism certainty of strata slicing.This study shows that seismic sedimentological study restricted by the 4th order sequence provided a powerful technical support for lateral reservoir prediction of thin gravity-flow sandstones fed by delta,and provided a foundation for reconstruction of depositional process and deepening the understanding of depositional rules of deep-water gravity flows.

关 键 词：重力流 储集层预测 层序地层学 地震沉积学 东营凹陷 渤海湾盆地 

分 类 号：P618.13[天文地球—矿床学]