A Numerical Simulation Method for Coal Seam High Pressure Water Injection Fracture-Seepage Flow

Abstract

The invention discloses a coal seam high-pressure water injection fracturing-seepage numerical simulation method based on the least pressure relief path algorithm. The coal body geometric model is established according to the water injection coal seam height, the direction length and the inclination length, and on this basis according to the diameter of the water injection hole , length, inclination and sealing length parameters to add the water injection hole model, add the fracture model according to the width, distribution and direction of the original fracture, and finally make it form a union through Boolean operations, carry out tetrahedral mesh division on the coal geometric model, and find The grid set that is most vulnerable to damage is considered as having generated fractures and marked as "calculation cracks" in the original geometric model, and the above algorithm steps for finding "calculation cracks" are repeated until the strength parameters of all grids are not low Based on the stress it receives, the path formed by the combination of the obtained grids is the most economical pressure relief path, that is, the path of fracture generation and development. Accurately simulate hydraulic fracturing and provide relevant data for decision makers on the law of water migration in coal.

Description

technical field [0001] The invention relates to the field of mine safety, in particular to a coal seam high-pressure water injection fracturing-seepage numerical simulation method based on the least pressure relief path algorithm. Background technique [0002] Coal seam water injection can effectively wet the coal body, release the elastic energy of the coal body, increase its plasticity, change the adsorption-desorption gas characteristics of the coal body, and have the effect of displacing gas. One of the common methods of highlighting with gas. However, due to the complex structure of pores and fissures in the coal body and the inability to effectively monitor the water seepage process, it is difficult to carry out experimental research on the law of water migration in the coal body. At the same time, with the rapid development of modern computing technology and the gradual maturity of rock mechanics and computational fluid dynamics, simulation has become an important me...

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Problems solved by technology

[0003] However, in the process of high-pressure water injection in coal seams, the coal body is prone to cracking and cracks under the action of water pressure, and the existing simulation software based on the finite element method is difficult to simulate the coupling flow field while calculating the development of cracks, that is, the model The fissures in must be preset and cannot be changed, which is seriously inconsistent with the actual project

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