The Theory And Application Research Of Fluid-solid Coupling Percolation In Deformed Media Gas Reservoir

In the developing of the deformed media gas reservoir, the change of pore fluid pressure will bring the deformation of rock matrix. On the contrary, the deformation will bring the change of pore volume, which can lead to the change of the physical parameters, such as porosity, permeability and pore compressibility. Thus, it will influence the percolation of pore fluid and the exploitation of the gas reservoir. Therefore, the percolation of the deformed media gas reservoir is a process with the strong dynamic coupling between the fluid percolation and the rock deformation.On the base of the studies of the deformation of reservoir rock matrix and the fluid percolation, and using many kinds of subjects and methods, such as gas reservoir engineering, fluid mechanics in porous medium, rock mechanics, computing mathematics, etc al., this paper firstly establishes a new and rounded mathematical and numerical model of fluid-solid coupling for deformed media gas reservoir. The model considers the influence of the rock deformation and the choice of rock constitutive model on the percolation. Subsequently, the fluid-solid coupling numerical simulation software according to the above model is successfully developed. And with this software, the simulation evaluation has been conducted on the actual deformed media gas reservoir.The study of this paper has prodigious difficulty and profundity. Through the studies in this paper, the acquired achievements are as follows:1) Based on the analysis of rock stress and strain, with the effective stress principle and rock matrix constitutive relation, the mathematical model of rock deformation of fluid-solid coupling has been established for the deformed media gas reservoir.2) According to the basic conception of fluid-solid coupling percolation theory and considering the basic character of deformed media gas reservoir percolation, the mathematical model of fluid percolation of fluid-solid coupling has been established for the deformed media gas reservoir in conjunction with the percolation mechanics, rock mechanics and geomechanics. Thus, the fluid-solid coupling model of gas-water percolation is composed of the rock matrix balance equation and the fluid flow continuity equation. They contains coupling factors each other and also depend on each other, which are a group of partial differential equations solved by coupling with numerical methods.3) Through summarizing former results of physical parameters dynamic model, the calculation models of dynamic variation on porosity, permeability, pore compressibility andsimilar physical parameters needed when solving fluid-solid numerical simulation in deformed media gas reservoir are given.4) The mathematical model of fluid percolation and rock deformation of fluid-solid coupling is solved with the finite difference method and the finite element method respectively. With the above two model combination, based on the basic conception of iterative coupling solution, the coupling calculation software is developed with Visual Fortran.5) With the above software, the actual simulation study has been made on the fluid-solid coupling percolation of deformed media gas reservoir.In this paper, the established fluid-solid coupling theoretical study method, mathematical model and developed numerical simulation software can be available to analyze the effects of rock deformation on the development index and of model selection on the production performance. The tests and practical application of this model have proved that it is correct and reliable. And it plays a significant role in actually simulating the development in deformed media gas reservoir and guiding its production.