Study On Sedimentary Characteristics And Reservoir Architecture Of The Es₁s Formation,Liu70 Fault Block,Raoyang Depression

After more than 40 years of exploration and development,the Liu70 fault block in Dawangzhuang Oilfield has a geological reserves recovery of only 13.5%,which shows poor utilization of the oil layer,low oil recovery rate,and difficulty in tapping potential.During the development process,it was found that the spatial distribution characteristics of the target layer sand bodies and the unclear understanding of the superposition relationship of sand bodies are the main factors restricting the low efficiency of oilfield exploitation.Therefore,the study of sedimentary facies and sedimentary microfacies in the study area and the evaluation of the contact relationship between sand bodies are of practical significance for the subsequent formulation of adjustment and development plans for the oilfield.This study is guided by the high-resolution sequence stratigraphy study,taking into account factors such as sand body superposition and lateral sedimentary phase transition in the stratigraphic correlation process,and established an isochronous stratigraphic framework and divided and compared the single layers in the study area for Liu70 fault block of Dawangzhuang oilfield.Based on the division of single layers,applying theories such as sedimentology,structural geology,and logging geology,and relying on the study of the regional sedimentary model in the Dawangzhuang oilfield,using data such as cores,cuttings,logging curves,analytical tests,etc.The sedimentary facies and sedimentary microfacies in the study area were studied.The results show that:the Es1s formation in the Liu70 fault block of Dawangzhuang oilfield is mainly controlled by provenances in the southwest,and delta front sedimentary subfacies are developed and subdivided into sedimentary microfacies such as underwater distributary channels,matte sands,mouth bars,diversion channel,etc.Among them,mouth bar sand bodies are the main reservoir sand bodies in the study area.Based on the study of sedimentary facies and sand body distribution characteristics,through the dissection of the internal structure of the sand body,the evaluation of the sand body superposition relationship and the sand body contact relationship was carried out,and the combination of "analytic hierarchy" and "model fitting" was used.The research idea is to divide the mouth bar reservoir sand body into three stages:composite mouth bar,single mouth bar and its internal accretion bodies.The length and width of the single bar sand body have obvious positive correlation;the single bar sand body develops 1-3 stage of hyperplasia,0.1-0.8m thick muddy interlayers were developed between the hyperplasias.The interlayers were approximately horizontally distributed in the direction of the single bar sand body near the lake shoreline,and inclined at a low angle toward the object edge in the center of the single bar sand body.The research on the scale and distribution characteristics of the internal structural elements of the reservoir shows that the distribution of the single bar sand body in the lateral side of the Liu 70 fault block includes two types of "butting" and "cutting",and the vertical is divided into "superimposed" and "cutting" with two contact types of "stacked type",each type of sandbody exhibits different connectivity characteristics;These achievements and knowledge have important guiding significance for the fine development of oil fields.