Three-dimensional simulation method of gas enrichment and transportation in goaf

Abstract

The invention discloses a three-dimensional simulation method of gas enrichment and transportation in a goaf. The method comprises the steps that a three-dimensional analogical simulation experiment is conducted according to an on-site working condition, and stress strain data of three-dimensional fracture form distribution distribution of overlying rock strata in the goaf are obtained; a true-triaxial fluid-solid coupling experiment is conducted on on-site coal rock samples, and basic parameters of numerical simulation are obtained; according to simulation experimental body fracture data after the simulation experiment, the data are converted into a digital model through three-dimensional drawing software, and quantitative description is conducted on a fracture form in the goaf; by means of the digital model, by combining COMSOL numerical simulation software, the gas permeability is calculated by means of a fluid-solid coupling experiment result and stress change data in the simulation experiment, a simultaneous solution is conducted on an air flow model and a gas diffusion model, and the gas transportation and enrichment range of the goaf is obtained. The three-dimensional simulation method of the gas enrichment and transportation in the goaf has the advantages that the gas enrichment and transportation range in the goaf is obtained through the three-dimensional simulation experiment, the true-triaxial fluid-solid coupling experiment and the COMSOL numerical simulation software, and the exhausting and mining hole position is determined accurately.

Description

technical field [0001] The invention belongs to the field of gas drainage, in particular to a three-dimensional simulation method for gas enrichment and migration in a goaf. Background technique [0002] As a new energy gas that can be used, coal seam gas is also a threat to the safe production of coal mines. In order to better solve the problem of gas disasters in mine production, my country mainly adopts drainage technology to deal with the gas existing in coal seams. Extraction and utilization to a certain extent have played a role in turning waste into treasure. However, the existing gas drainage technology has encountered many problems, such as low gas permeability of coal seams, great difficulty in gas extraction, unstable gas volume in drilling holes, and so on. Pre-drainage of unmined coal seams in high-stress environments has low gas permeability, difficulty in gas extraction, and small gas extraction volume; compared with pre-drainage of coal seam gas, the goaf wit...

AI Technical Summary

Problems solved by technology

However, the law of gas migration and enrichment in the working face and goaf is not very clear, and traditional drilling methods often cannot determine the correct drilling position

[0005] For high-gas mines, the common practice in China is to drain first and then mine. However, the existing gas drainage technology has encountered many problems; The drainage effect is relatively good, but the management is complicated

Therefore, it is very important to determine the law of gas migration and enrichment in the working face and goaf; because the existing numerical simulation software cannot solve the problem of gas migration under the deformation of rock formations and the coupling of multi-physics fields at the same time, There is also a lack of research on the change law of rock formation permeability under different beddings and different intermediate principal stresses. Calculating the gas migration and enrichment range simply by numerical simulation will bring large errors

At the same time, the existing experimental methods are difficult to inject gas during the simulated excavation process and monitor the gas concentration and flow rate in real time

Existing experimental and simulation methods are difficult to accurately reflect the distribution of fissures in goafs, so it is difficult to determine the migration and enrichment areas of gas goafs, and there is limited guidance for the determination of drilling positions in goafs

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