Experimental Study Of Permeability Enhancements Mechanism Under High Pressure Water Jet Cutting In Low-Permeability Coal Bed

Coal is the main energy in our country to promote economic development. Gas is the major potential threat during coal mine production, but meanwhile is the high-quality and efficient clean energy. In our country, most of the coal bed is low-permeability. Especially in recent years, because of the deepening exploitation of the coal bed, gas contents and pressure is increasing with the increased Ground Stress, thus the prominent risk gets larger which needs the good gas control technology urgently. The gas drainage technology is one of the important ways to improve the low-permeability single coal bed gas drainage effect.This paper starts from the research of structure characteristic of low-permeability coal bed; with low-permeability coal bed pore fracture structure as objects, based on the aspects of in-situ stress, gas pressure and the pore structure, analyzes the influence on permeability coal bed. Aiming at characteristics of low-permeability coal bed gas, this paper dissertates the gas storage migration mechanism from the aspects of desorption, desorption, diffusion, seepage respectively.Based on the similarity theory, using the similar material model to simulate low-permeability coal bed, by high pressure water jet cutting, using pressure box embedded way to monitor stress variation in model at different sites before and after cutting, combining the displacement of the displacement meters and model permeability change, data analysis of the model stress, displacement, permeability variation rule before and after cutting, to provide experiment basis for enhancements mechanism of low-permeability coal bed.By analyzing experimental research, this paper gets the conclusion that based on the structure of coal bed cutting load relief under the status of confined, the coal on the both sides of slot will be deformation. The stress will be the complex status after stress redistribution. The upper coal displace downward due to slot pressure relief, the break zone produced around slot, coal bed gas appears the nonlinear seepage characteristics of partition area. From the aspect of cutting coal bed structure, dynamic mechanism and gas nonlinear seepage to reveal cutting permeability enhancements mechanism.