A multi-scale numerical simulation method of fluid-solid coupling in shale gas reservoirs

Abstract

The invention discloses a multi-scale numerical simulation method of fluid-solid coupling in shale gas reservoirs, which includes: obtaining the spatial distribution and physical property parameters of organic matter and inorganic matter, constructing a physical model of micro-scale shale matrix, solving micro-scale seepage auxiliary equations and Auxiliary mechanics equations to calculate the equivalent seepage and mechanical parameters of the shale matrix core scale; obtain the distribution of natural fractures, construct a core-scale physical model including shale matrix and natural fractures, and solve the core-scale seepage auxiliary equations and mechanical auxiliary equations, Calculate the macro-scale equivalent seepage and mechanical parameters of shale gas reservoirs; on this basis, the embedded discrete fracture model is used to simulate hydraulic fractures, and the macroscopic fluid-solid coupling model of shale gas reservoirs is established; finally, based on the structured grid, the The hybrid numerical discretization method combining finite difference simulation and extended finite element method solves the fluid-solid coupling model of shale gas reservoirs, and realizes the fluid-solid coupling numerical simulation of shale gas reservoirs with high simulation accuracy and small calculation amount.

Description

technical field [0001] The invention relates to the field of reservoir numerical simulation, in particular to a multi-scale numerical simulation method for fluid-solid coupling of shale gas reservoirs Background technique [0002] Shale gas resources are widely distributed and have large reserves, but the permeability of the reservoir matrix is ​​extremely low, and hydraulic fracturing is usually required for commercial exploitation. After fracturing, shale gas reservoirs develop a large number of fractures and are in a complex in-situ stress field In the joint action of the seepage field and the seepage field, the fluid-solid coupling effect is significant. At the same time, shale gas reservoirs contain multi-scale storage and seepage spaces: micro-scale organic and inorganic pores, core-scale natural fractures, and macro-scale artificial fractures. However, the current macroscopic numerical simulation methods for shale gas reservoirs are difficult to accurately capture th...

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Problems solved by technology

However, the current macroscopic numerical simulation methods for shale gas reservoirs are difficult to accurately capture the mechanical and seepage characteristics of micro-scale organic matter and inorganic matter and core-scale natural fractures, and based on lattice Boltzmann, directly solving N-S equations and discrete elements, etc. The calculation area of ​​the micro-scale numerical simulation method of the method is too small to be directly used for large-scale actual reservoir-scale problems

In addition, the existing fluid-solid interaction model solution methods usually use the finite volume method and finite element method to discretize the seepage field equation and the stress field equation. This method needs to be based on an unstructured grid or a locally refined grid to explicitly simulate the seepage of hydraulic fractures. and deformation features, so there are problems of difficult mesh division and large amount of calculation

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