The Study Of Fluid Flow Mechanism With Sand Erosion And Sand Particulates Migration In The Reservoir And Fluid-Solid Coupling Single-Well Numerical Simulation

In this thesis, a new concept, reservoir numerical simulation of fluid-solid coupling flow with sand erosion and sand particulates migration, has been put forward, based on mechanisms of dynamic coupling of fluid flow and sand particulates erosion, migration, deposition, bridge plug and wall rock elasto-plastic deformation in recovery process of oil well. A study has been conducted for the first time on the theory of fluid-solid coupling flow with sand erosion and sand particulates migration and methods involved in the simulation, which resulted in creative achievements which have great significance on guiding formation development with sand production.On the basis of existing experimental and theoretical research results, a novel and complete set of theoretical models on single-well numerical simulation of fluid-solid coupling flow with sand erosion and sand particulates migration has been established for the first time through comprehensive research of multi-discipline, combining mechanics of flow through porous media, geomechanics and elasto-plastic mechanics. A series of techniques and methods for implementing such simulation have been sought out, and a single-well numerical simulator, which can be run on PC and based on the theory of fluid-solid coupling flow with sand erosion and sand particulates migration, has been developed. A case study has been conducted to verify the correctness and validity of the theory and methods presented in the thesis, and to verify the validity of the simulator developed.About models establishment: New criteria for the damage of the rock skeleton and startup of movable sand have been set up through comprehensive research of multi-discipline and provide solid basis for the establishment of single-well numerical simulation models of fluid-solid coupling flow with sand erosion and sand particulates migration. On the basis, motion equation of fluid and movable sand, constitutive equation of the rock skeleton sand erosion, deposition equation of movable sand on the pore surfaces and block equation of movable sand at pore throats have been set up through the research in which movable sand is viewed as one phase of fluid for the first time. In the light of principle of mass conservation, single-well black oil model with three dimensions, four phases of fluid-solid coupling flow considering sand erosionand sand particulates migration has been established. Then, according to the property oi elasto-plastic deformation of oil well wall rock, constitutive model of elasto-plastic deformation of oil well wall rock has been established. In the light of the effective stress principle and static equilibrium condition, the equilibrium differential equation for elasto-plastic deformation of oil well wall rock has been established. About the dynamic models of physical property parameters, considering the effect of volumetric strain, skeleton sand erosion, movable sand deposition on the pore surfaces and movable sand block at pore throats, they have been established for single-well numerical simulation of fluid-solid coupling flow with sand erosion and sand particulates migration. The criteria and models, which have been established, are made of complete single-well numeric simulation model of fluid-solid coupling flow considering sand erosion and sand particulates migration.About the solution to the model: According to the basic principle of finite difference, the finite difference methods for solving single-well model of fluid-solid coupling flow considering sand erosion and sand particulates migration have been studied. According to the basic principle of finite element, the finite element methods for solving elasto-plastic deformation model of oil well wall rock of fluid-solid coupling flow considering sand erosion and sand particulates migration have been studied. According to the relationship between the finite difference methods solving the model of fluid flow considering sand erosion and sand particulates migration and finite element methods solving the model of elasto-plastic deformation of oi...