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针对低透气性煤层瓦斯抽采难度大、工作量大、效率低等问题,采用水力压裂技术促进煤层瓦斯抽采。在多场耦合和弹性损伤理论基础上,建立煤层损伤-应力-渗流耦合模型,数值模拟马堡煤矿15108工作面水力压裂及瓦斯抽采过程,分析煤层弹性模量、渗透率和瓦斯压力的变化规律,确定压裂和抽采关键参数,并据此开展工程试验,对模拟结果进行验证。结果表明:高能压裂液能使煤层破裂,渗透率急剧升高,加快瓦斯向抽采钻孔运移;随着压裂时间增加,压裂损伤范围逐渐扩大;模拟得出水力压裂10 000 s时,2个压裂孔间的损伤区在抽采孔处贯通,压裂损伤范围达14 m;现场压裂试验后,瓦斯抽采平均和最高纯量分别达到63.79和126.57 m3/d,是未压裂的9.65倍和7.23倍,透气性升高了67倍。
In view of the difficulty of gas drainage in low permeability coal seam, such problems as heavy workload and low efficiency, hydraulic fracturing technology is used to promote gas drainage in coal seam. Based on the theories of multiple couplings and elastic damage, a coal seam damage-stress-seepage coupling model is established to simulate the hydraulic fracturing and gas drainage process of No.15108 face in Marburg coal mine, and to analyze the elastic modulus, permeability and gas pressure of coal seam Change law, determine the key parameters of fracturing and extraction, and carry out engineering tests accordingly to verify the simulation results. The results show that the high-energy fracturing fluid can rupture the coal seam and increase the permeability rapidly, which can speed up the gas migration to the borehole. As the fracturing time increases, the range of fracturing damage gradually increases. The simulation results show that the hydraulic fracturing s, the damage zone between the two fracturing holes penetrates through the extraction hole with the fracturing damage range of 14 m. After the field fracturing test, the average and maximum gas drainage capacities reach 63.79 and 126.57 m3 / d, respectively, 9.65 times and 7.23 times that of non-fracturing, and the air permeability increased 67 times.