Study On Core Structure Reconstruction And Mechanism Of Its Seepage Flow

As a kind of porous media,the reservoirs with large number of different sizes are usually complex and geometrically and spatially distributed,and they are connected to each other to form a complex pore network structure.The existence of complex pore structure inside the reservoir directly affects its physical and mechanical properties,and directly affects the reservoir energy storage and the internal fluid seepage behavior.The reservoir pore structure has an important influence on the exploitation of unconventional resources such as oil and gas and shale gas.It is helpful to evaluate the reservoir,and to improve the oil and gas production capacity and recovery rate by studying the characteristics of reservoir microcosmic pore shape,connectivity,pore size distribution and coordination number.According to the core microstructure CT images,the microscopic pore structure was studied by image processing method.Then,the parameters of the core image are reconstructed based on mathematical theory.Finally,the numerical simulation m ethod is used to study the relationship between the core structure parameters and th e leakage method.The main work of the paper is as follows:(1)The core microstructure of the core pore structure parameters(such as aper ture,throat radius,porosity,etc.)and pore structure connectivity were studied by us ing the core CT image processing software,and the core microcosmic pore structur e Statistical model.(2)Based on the established statistical model,the core image of sandstone is selected,and the maximum sphere theory of pore structure reconstruction is used to establish the pore structure network model,and the parameters of the network model are calculated.(3)Based on the established model of pore structure network,three-dimensional micro-pore structure model was reconstructed by three-dimensional microstructure reconstruction software Mimics,and a three-dimensional digital IGES model of core micro-pore structure was generated randomly.(4)The equivalent permeability of the core is calculated by using the Abaqus software to calculate the equivalent permeability of the reconstructed core.The relationship between the equivalent permeability of the core and its pore characteristic parameters is calculated,and the equivalent permeability coefficient and pore structure of the core are established.The relationship between the parameters is established,and the calculation model of the core equivalent permeability with the microscopic pore structure parameters of the core is established.