埕海油田张东地区沙河街组沉积特征分析

摘要

本文通过粒度、岩性、沉积构造、测井曲线以及沉积微相平面图等资料的综合分析，结合区域地质背景，对埕海油田张东地区沙河街组沙三段、沙二段、沙一段进行了详细的划分、描述。研究区沙三段沉积呈典型的正粒序结构，上细下粗，为三角洲前缘亚相，主要砂体类型包括河口坝、水下分流河道及前缘席状砂。储层特征表现为中孔-中渗、中孔-低渗、低孔-特低渗，孔隙以粒间、颗粒和粒内溶孔为主，于晚成岩A阶段形成；沙二段形成于三角洲沉积环境（滨浅湖），属于低位体系域，砂体发育，规模大，为张东地区最为有利的储集层，是今后勘探的重点靶区；沙一段主要为白云岩、泥灰岩、和油页岩的互层沉积，局部地区发育薄层粉砂岩，可以作为很好的盖层和烃源岩，沉积环境为比较闭塞的静水！湖环境。%The Zhangdong district,Chenghai Oil Field,Hebei is very complicated in geological structures and thus less explored in petroleum exploration. The authors in the present paper give a detailed division and description for the Shahejie Formation as main oil-bearing rock series in the Zhangdong district on the basis of grain sizes, lithology,sedimentary structures, sedimentary microfacies and well logs. The third member of the Shahejie Formation displays the typical normal graded structures,and belongs to the delta front subfacies including the channel mouth bar,subaqueous distributary channel and delta front sheet sands microfacies. The sandstone reservoirs are characterized by moderate porosity to moderate permeability,moderate porosity to low permeability, low porosity to extra-low permeability,and intergranular,granular and intragranular solution openings generated during the A stage of late diagenesis. The second member of the Shahejie Formation is organized in the delta ( littoral to shallow-lake)environment in the lowstand tracts system,and occurs as the best favourable hydrocarbon reservoirs and target area in the Zhangdong district. The first member of the Shahejie Formation is built up of the dolostone-marl-oil shale couplets,locally with thin-bedded siltstones as good cap rocks and source rocks deposited in the relatively enclosed stationary lagoon environment.