Study On Geological Modeling Of Huagang Formation Gas Reservoir In Xihu Sag

X gas field is located in the Xihu sag of the East China Sea Basin.The X gas field is a low permeability reservoir at sea with a deep depth and little wells which has a characteristics of strong heterogeneity.The distribution of the dominant reservoir is still unclear and the model has a low precision and a poor development of gas reservoir.In order to solve these problems,this paper starts from the sedimentary characteristics of this area and the distribution of the dominant reservoirs.On this basis,the quantitative criteria and distribution of " sweet point " are determined,and establishing the model constrainted by the probabilistic volume on the basis of it which can provide foundation for gas reservoir development.In this paper,the geological results including the core,logging and seismic data are used to study the sedimentary characteristics of this area which determine the quantitative criteria of "sweet point ".indicating the elastic parameters and physical parameters are the main criteria for dividing the " sweet point " Based on the study,it is considered that the " sweet point " is mainly developing in the underwater distributary channel microfacies,and the distribution of " sweet point " is completed with the seismic attributes results.On the basis of geological studying,combining well and sesmic to establish reservoir geological model.Using fault interpretation and seismic inversion structural surface to establish structural model.Facies modeling of tight gas reservoir in less well area on the sea is one of problems which are eager to overcome.Aiming at solving high heterogeneity of tight sandstone gas reservoirs in braided river deposits,it is difficult to accurately characterize reservoir's distribution of "sweet point" and properties using conventional geological modeling method.In this paper,using "sweet point" controlling,multiple-point geo-statistics and probabilistic volume constraint on thick layer Reservoirs in the East China Sea,we have innovatively modeled using "sweet point" in a form of facies and generated training image in different ways considering different kinds of "sweet point" and simulated facies based on Poisson's ratio volume and "sweet point" probabilistic volume as a second constraint.The results shows that simulating "sweet point" in the form of facies by using multiple-point can overcome limitation of single facies and characterize the spatial structure of "sweet point".The result is in line with geological knowledge by using different training images in different members.The prediction accuracy of distribution of "sweet point" has been improved under the constraint of probabilistic volume.According to the principle of facies modeling,under the constraint of seismic inversion porosity,porosity parameters are taken into account for sequential Gaussian simulation,and porosity model acts as the second variable constraint on permeability parameters sequential Gaussian co-simulation.The models are fitted with reserves and tested by models comparison and probability distribution consistency whose results demonstrate the geological models are of high precision.