Reservoir Geological Modeling And Evaluation Of Es₃ In Chengbei Sag

The Es₃ sedimentary period is in the midst of a downfaulted lake basin expansion of Chengbei Sag,there has many types,multiple sedimentary body,and has the geological conditions of forming large reservoir.But the drilling mainly concentrated in the gentle slope,sub-sag,it is difficult to analyze accurately by conventional geological methods.In order to solve the problem of shortage of well data,this paper research the reservoir geologic modeling.The method can directly reflect the reservoir of the three dimensional spatial distribution characteristics and made it possible to accurately forecast favorable reservoir.In order to improve the modeling accuracy,this study integrated use well data and seismic data,give full play to the high longitudinal resolution of well data and the advantage of lateral prediction of seismic data.First of all,on the basis of preliminary study of geology,this paper establish the time domain structural framework model based on accurate structure interpretation,and then transform time domain structural framework model to depth domain model;Then,single well data as the first variable,variogram and seismic data as the second variable,using sequential indicator simulation method establish the distribution of facies model.This study use the qualitative geological concept model test and thin well test to check accuracy.In the thin well test,each lithofacies distribution probability and original analog probability value,and smoke sparse wells in different lithofacies distribution and the distribution of degree is high;With well data drew sandstone isopach map,and the sand body distribution trend of the scope and the theoretical results fit well with 3D facies model.Verification results show that the 3D facies model has high accuracy,and can reflect the reservoir features of the study area,and it also has good interwell prediction.On the basis of the study,this paper evaluate the reservoir and found that the gentle slope belt of reservoir physical property is best.At the same time,point out that pore porosity is greater than 8%,permeability is greater than 2×10^-33 um² for effective reservoir.Then determine the different structural belt of effective reservoir lower limit depth,steep slope zone depth limit is 3650m,depression zone depth limit is 3950m,gentle slope zone depth limit is3700 m.According to the results of modeling and reservoir evaluation results,this paper choose oil-bearing layer 6-8 sand groups to reservoir prediction.The result show that the facies less than 3950 m of sandstone facies in steep slope zone and less than 3700 m of sandstone facies in gentle slope are the favorable sand body for study.