渤海海域明化镇组下段砂体构型与连通性分析

Analysis of sand architecture and connectivity in lower member of Minghuazhen Formation in Bohai Sea

渤海海域浅层明化镇组下段时期,沉积体系复杂、类型多样,已发现的岩性油藏主要发育在曲流河和浅水三角洲中,砂体横向变化快,接触关系复杂,形成了储层空间展布及内部结构复杂的砂体,砂体构型及连通性决定了砂体发育规模及其展布范围,控制了岩性圈闭的大小及其油气分布。根据岩心、测井和地震等资料,对渤海海域浅层明化镇组下段砂体构型开展精细解剖,建立复杂沉积体系砂体构型模式,开展储层构型控制的砂体分布及演变特征研究,分析单砂体内部连通性。结果表明:曲流河砂体之间垂向叠置关系包括独立型、叠加型与切叠型,平面叠置关系主要以侧接型为主,以条带状展布为典型特征;浅水三角洲砂体构型要素主要由分流河道、河口坝和席状砂组成,垂向上以对接型、切叠型为主,平面上呈现枝状、朵状和片状展布。在砂体构型样式分析的基础上,运用三维地震、地球化学等资料和手段,结合构造和沉积特征,通过砂体叠置模式对比、原油运移充注分析和三维地震储层预测技术等方法,有效判识了明下段砂体的连通性,为浅层岩性圈闭落实和大面积岩性勘探提供借鉴。

In the lower member of the Minghuazhen Formation in the shallow Bohai Sea,the sedimentary system is complex and diverse in types.The discovered lithological reservoirs are mainly developed in meandering rivers and shallow water deltas.The sand undergoes rapid lateral changes and complex contact relationships,forming a sand with complex spatial distribution and internal structure of reservoirs.Sand architecture and connectivity determine their development scale and distribution range and control the size of lithological traps and the hydrocarbon distribution degree.Based on core,logging,and seismic data,a detailed dissection of the sand architecture in the lower member of the Minghuazhen Formation in the shallow Bohai Sea was conducted,and a sand architecture model with a complex sedimentary system was established.The distribution and evolution characteristics of sand controlled by reservoir architecture were studied,and the internal connectivity of sand was analyzed.The results indicate that the vertical stacking relationship of meandering river sand includes independent type,superimposed type,and cut-overlap type.The planar stacking relationship is mainly dominated by lateral connection type,with strip-shaped distribution and development as the typical characteristics.The architecture elements of shallow water delta sand is mainly composed of distributary channels,mouth bars,and sheet-like sand.Vertically,they are mainly of butt and cut-overlap types.Horizontally,they exhibit branch,lobe,and sheet-like distribution and development.On the basis of analyzing the architecture style of sand,seismic,geochemical,and other data and methods were used.Combined with structural and sedimentary characteristics,the connectivity of sand was analyzed through methods such as superimposed sand pattern comparison,crude oil migration and filling analysis,and 3D seismic reservoir prediction technology,providing a reference for the implementation of shallow lithological traps and large-scale lithological exploration。