东非鲁伍马盆地下始新统深水沉积储层特征及沉积演化  

Reservoir characteristics and sedimentary evolution of deep water deposition of lower Eocene in Rovuma Basin,East Africa

作　　者：曹全斌 鲁银涛 陈宇航[2,3] 王瑞峰 曹旭文[5] 马宏霞 庞旭 CAO Quanbin;LU Yintao;CHEN Yuhang;WANG Ruifeng;CAO Xuwen;MA Hongxia;PANG Xu

机构地区：[1]中国石油杭州地质研究院 [2]中国科学院海洋地质与环境重点实验室 [3]西安石油大学 [4]中国石油勘探开发研究院 [5]国家海洋局第二海洋研究所

出　　处：《海相油气地质》2022年第4期396-404,共9页Marine Origin Petroleum Geology

基　　金：中国石油天然气集团有限公司科技项目“海洋油气勘探关键技术研究”(编号:2021DJ24);中国科学院海洋地质与环境重点实验室开放基金课题“海洋裂谷盆地深水沉积源-汇过程研究——以东非鲁伍马盆地为例”(编号:MGE2020KG10);国家自然科学基金项目“伸展构造对深水扇沉积的控制机理研究——以东非鲁武马盆地海底深水扇为例”(编号:41802128)联合资助

摘　　要：针对东非鲁伍马盆地深水沉积体系演化的复杂性,基于地震资料和钻井资料等资料,对古近系下始新统深水沉积特征及深水沉积体系演化期次进行分析研究。结果表明:下始新统深水沉积体系发育碎屑岩和碳酸盐岩两种岩石类型,天然气主要分布在泥质含量低、颗粒分选程度高的富砂岩相中;储层成岩作用不强,孔隙类型以原生粒间孔为主;岩相和岩石结构成熟度是影响储层质量的主要因素。下始新统深水沉积体系可以进一步细分为5期沉积。受重力流和底流共同作用,深水沉积体系总体表现为由北向南迁移的特点,主要为水道沉积,晚期受海底底形影响演化为朵体沉积。认为研究区内4口天然气发现井的储层属于3个不同期次的深水沉积砂体,气藏评价需考虑3个气藏砂体之间的连通性。In view of the complexity of the evolution of deep-water sedimentary system in Rovuma Basin,East Africa,based on seismic data and drilling data,the sedimentary characteristics and its evolutionary stages of the Paleogene lower Eocene deep-water sedimentary system are analyzed and studied.The results show that two rock types,i.e.clastic rocks and carbonate rocks,are developed in the target layer.Clastic rocks are divided into two types of lithofacies:sand-rich and mud-rich,and the natural gas was found in the sand-rich facies with low argillaceous content and high degree of particle sorting.The diagenesis of the reservoir is not strong,and the pore type is mainly primary intergranular pore.The lithofacies and rock texture maturity are the main factors affecting the quality of the reservoir.The lower Eocene deepwater sedimentary system can be further subdivided into five depositional stages(A,B,C,D,and E).Carbonate clastic flow depositions are developed at stage A,and clastic rocks are developed at stage B-E.The reservoir of stage B is tight because of high content of carbonate rock clasts,and the reservoir quality of stages C,D and E is good.Influenced by the interaction between gravity flows and bottom currents,the sedimentary system is characterized by migration from north to south and evolved from channels to lobes in the late stage when the channels are the main type of sedimentary structural unit.The reservoirs of four natural gas discovery wells in the study area belong to deep-water sedimentary sand bodies of three different stages,and the connectivity between the three sand bodies should be considered in gas reservoir evaluation.Development well locations should be rationally deployed to ensure full development of the gas reservoir.

关 键 词：深水沉积 沉积演化 沉积模式 鲁伍马盆地 东非 

分 类 号：TE121.32[石油与天然气工程—油气勘探]