Research Of Sedimentary Facies And Reservoir Of Jurassic Qigu Formation J₃q₃ In Zhong 18 Wells Block In Fengcheng Oilfield

Fengcheng oilfield is located in the northwestern margin of Junggar basin,belonging to shallow super heavy oil reservoir,reservoir is the main period of J₃q₃member.The regional capacity building is of positive significance for the stable and stable development of the Xinjiang oilfield and the development of the west strategy..In this paper,based on the former research results,combined with geological conditions in the study area,under the guidance of sedimentary petrology,reservoir geology,combined with core observation and description,well logging,logging and core sample analysis of experimental data analysis of 18 wellblock sedimentary facies analysis,reservoir research and reservoir classification and evaluation,research and provide scientific basis for later exploration of reservoir deployment.The main recognition is as follows:On the basis of regional geological background,combined with feldspar content level changes and ZTR index plane distribution and identify the J₃q₃ provenance direction mainly composed of northwest to southeast direction.The main lithology is fine sandstone,middle and fine sandstone,gravel bearing sandstone,sandy gravel,mudstone and sandy mudstone..Sandstone components are mainly volcanic detritus,quartz,feldspar,miscellaneous base is mainly mud and kaolinite,calcite is the main cementing material,containing trace amounts of siderite,sorting good to poor,grinding roundness sub angular to sub rounded mainly,contact to line contact,degree of cementation of loose medium,type of cementation mainly pore type.The probability granularity curve is mainly composed of two stages,which is composed of the suspended population and the jumping population..Core observation visible horizontal bedding,parallel bedding,cross bedding scouring surface sedimentary structure.Combination of logging facies analysis,objective sedimentary facies is braided fluvial and identify the riverbed lag deposits,beach,braided shaped channel,and floodplain sedimentary microfacies types.The purpose of the study area is mainly debris sandstone,the structure maturityand composition maturity are relatively low.The main pore types are primary intergranular pores,intergranular pores,intergranular dissolution pores,dissolution pores and fractures,etc..Which is the primary porosity,the dissolution porosity and the micro fissure are less..The average porosity and permeability of reservoir are both high,and the reservoir is high porosity and permeability..Considering the factors of reservoir physical property and sand body size,reservoir is divided into three categories:Ⅰ1 good reservoir,Ⅰ2 medium reservoir and class II difference reservoir..