Study On The Distribution Characteristics Of Base Rock Weathered Crust Reservoir In The West Belt Of Chenjiazhuang Uplift In Dongying Depression

Base rock reservoir is one of the most important types of oil and gas reservoir.Medium and large-scale bedrock reservoir has been found in the western belt of Chenjiazhuang Uplift.Base rock reservoir is an important area for further exploration in Jiyang Depression.Due to the lack of dynamic process analysis on the formation and evolution of weathered crust of base rock and the lack of research on the transformation and preservation of base rock reservoir,the existing geological distribution model of base rock reservoir is difficult to apply in the work area,which makes it very difficult to predict the distribution of weathered crust of base rock reservoir.In this paper,through rock observation,thin section analysis and outcrop analysis,combined with logging,logging and seismic data,the comprehensive research method of Geology and geophysics is adopted to study the structural characteristics,formation mechanism and main control factors.The types of effective reservoir in bedrock are determined,the distribution model of bedrock reservoir is established,and the distribution of favorable reservoir in bedrock is predicted.Firstly,a double-layer structure of weathered crust of base rock in the work area is put forward,in which the upper part of weathered crust develops dissolution layer or residual layer,and the lower part of weathered crust develops disintegrated layer.It is considered that the formation and evolution of weathered crust of base rock is a geodynamic process.The initial stage of weathering is the formation stage of disintegrated layer,and then the top of disintegrated layer develops dissolution layer in the middle and later stage of weathering.The dissolution layer evolves into residual layer,and the completely weathered layer disappears at the end of weathering,and only the disintegrated layer remains.Secondly,it is proposed that the present weathering crust has undergone a process of the formation,transformation and preservation.While the weathering crust is formed,it undergoes transformation and preservation.The distribution of the weathering crust in the working area is different.The disintegrated layer of the weathering crust is developed in the high part of the structural bulge.The residual layer is developed in the gentle slope area at the edge of the bulge.The dissolution layer is developed in the low part.Besides,seismic facies model of weathered crust of bedrock is established,and the distribution of base rock reservoir in the working area is predicted by using seismic data.Finally,the favorable distribution block of base rock reservoir is pointed out,and the favorable exploration direction of bedrock is predicted.It is considered that the middle and low part of the structure is the favorable weathering crust development zone.The medium amplitude phase is the favorable bedrock reservoir development zone,and the weathering crust reservoir in the low part of the structure is the favorable weathering crust development zone.Three favorable exploration targets of weathering crust reservoir are proposed.The development model of weathered crust of bedrock proposed in this paper is widely representative in Bohai Bay Basin and even fault basin,which has important guiding significance for the formation and distribution of base rock oil and gas reservoir.