Research On The Effective Electrical Model With Geometry Factor For Three-phase Composite

Underground resources can be considered as composites.Taking the oil and gas stored in rocks as an example,it can be simplified as a three-phase composite mixed with rock matrix,water,and oil(or gas).By studying the effective electrical model of three-phase composite,this thesis provides a theoretical reference for accurately predicting the range of water and oil(or gas)content in underground space.Researchers have proposed a variety of classical theoretical models for the effective electrical characteristics of composite,yet few have studied the effect of inclusion microgeometry on the effective electrical model.In this thesis,numerical simulation is carried out to compare with the theoretical models so the geometrical effect of inclusion variation can be investigated.A geometry factor is introduced to capture the influence of different inclusion arrangements,thus a new effective electrical model for the three-phase composite is established.The thesis work is carried out as follows:(1)The effects of inclusion microgeometry on the effective electrical characteristics of three-phase composite are studied by numerical simulation methods.In this thesis,COMSOL Multiphysics? numerical simulation software based on the Finite Element Method(FEM)is used to construct four inclusion geometric models and six three-phase models with different phase distribution.The effective electrical characteristics of the composite are obtained by numerically solving the partial differential equations of the electromagnetic field and the medium equation,and the effects of different inclusion geometries on the effective electrical characteristics of the three-phase composite are discussed.(2)Starting from the classical theoretical model of composite,the effect of inclusion microgeometry on the effective electrical characteristics of three-phase composite is studied analytically.By analyzing the assumptions of various classic models,a theoretical model consistent with the characteristics of the numerical model in this thesis is selected.Compare the numerical simulation results of effective electrical characteristics of three-phase composite with those of classical theoretical formulas,the change law of effective electric characteristics of three-phase composite with model structure is summarized.Because theclassical theoretical model does not consider the influence of the microgeometric structure of each component on the effective electrical characteristics of the composite,the analytical results of the theoretical model differ greatly from the numerical simulation results.This thesis introduces the idea of geometric factor modification,and revises the theoretical analytical formulas for the different geometric structures of the inclusions,so that the modified effective electrical characteristics model of the composite suitable for different phase distributions and inclusion microgeometry.(3)Construct a more complex eigenmodel of composite to make it closer to the actual distribution of underground resources such as water,and oil(or gas).The numerical calculation of the effective electrical characteristics of this eigenmodel is carried out by numerical methods and compared with the theoretical formula containing geometric factors proposed by the thesis to verify the modification effect of the formula.And use this modified theoretical formula to predict the content range of water,and oil(or gas)and other resources in the three-phase composite.The results show that the modified model of effective electrical characteristics of composite is suitable for different phase distribution and inclusion microgeometry,and the range of water and oil content in the eigen model can be directly predicted using the modified theoretical formula,the revised theoretical formula provides a theoretical reference for predicting the range of water,and oil(or gas)resources in underground space.