Effect of phase change fracturing of liquid CO2 in coal seams under geostress action
Based on the TNT equivalent conversion of liquid CO2 gas burst energy,LS-DYNA software is used to analyze the influence of blasting parameters(load volume,peak pressure relief and fracture hole diameter)and the effect of geostress on liquid CO2 phase change fracturing,and to carry out the liquid CO2 phase change fracturing engineering tests.The simulation results show that the effect of liquid CO2 phase change fracturing is positively correlated with the changes of load volume,peak pressure relief and fracture hole diameter,and negatively correlated with the ground stress,and the load volume and fracture hole diameter should not be too large;the test results show that the effective fracture radius of the coal seam is close to that of the test results(3.62 m)and simulation results(3.47 m),which verifies the reliability of the numerical model of blasting.After the application of liquid CO2 phase change fracturing technology to increase the permeability,the permeability coefficient of the observation holes at a distance of 1m from the fracturing holes is increased by 34 times,the gas outflow intensity of the observation holes at a distance of 2.5 m from the fracturing holes is increased by 3.23 times and the attenuation intensity is reduced by 87.93%,and the average gas extraction concentration of the observation holes at a distance of 1～1.5 m from the fracturing holes is increased by 64.38%.
CO2 phase change fracturingTNT equivalent conversiongeostressblasting parametersengineering test
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NSTL
万方数据
