Fluid-Solid Coupling Model Of Elasto-Plastic Porous Media And Its Application

Deep rocks usually have obvious plastic characteristics.Currently,research on porous media is mostly based on the elastic fluid-solid coupling model.The interaction between plastic deformation of rock and pore fluid cannot be ignored.Therefore,it is necessary to study fluid-solid coupling model of elasto-plastic porous media.In this paper,the theoretical model has be improved based on the elastic model,considering the plastic deformation of rock.At the same time,considering the yield of rock in the numerical simulation of hydraulic fracturing process.We study the influence of some parameters on the shape of hydraulic fracturing in elastoplastic formation.The influence of hydraulic fractures on long distance natural fractures is studied by analyzing the distribution of surrounding stress field and pore pressure field during the process of hydraulic fracture propagation.Studies have shown that decrease of the cohesive strength of the rock,increase of the initial pore pressure,increase of reservoir permeability,and increase of the liquid injection rate can lead to the increase of the plastic deformation of the rock near the fracture,resulting a wider and longer hydraulic fracture.Long-distance natural fractures will produce tensile or shear damage during hydraulic fracturing.And the distances between natural fractures and hydraulic fractures,stress differences,and permeability all affect the degree of interference.At the same time,creation of two or more concurrent hydraulic fractures cause less natural fracture activation between them.The above studies have important reference significance for the selection of the location of fracturing,the fracture spacing of horizontal well fracturing,and the design of fracturing time in the oil field.