CAJ | 학술논문

煤层中通常会通过注N2、CO2提高煤层气采收率或实现CO2埋存，注入的气体将使煤层中裂纹发生扩展，诱发煤层失稳。以宁武盆地9号煤层为研究对象，开展等温吸附实验定量研究了煤岩对N2、CO2的吸附量，并开展三轴压缩力学实验定量研究了N2、CO2吸附对煤岩力学强度的影响；分析了煤岩中裂纹扩展机理，根据断裂力学理论推导出含气煤岩中的裂纹扩展速度方程，并根据方程计算出注不同气体时煤岩中的裂纹扩展速度。研究表明，在相同平衡压力下，煤岩对CO2的吸附量是CH4的6倍；煤岩饱和CO2后的力学强度明显低于饱和N2的力学强度；煤层注CO2比注N2引起的裂纹扩展速度更大，并且注气压力越高扩展速度越大。该理论成果能够为优化注气的比例及注气压力提供理论指导，并且对防止煤层失稳，保障顺利注气具有重要意义。
매층중통상회통과주N2、CO2제고매층기채수솔혹실현CO2매존，주입적기체장사매층중렬문발생확전，유발매층실은。이저무분지9호매층위연구대상，개전등온흡부실험정량연구료매암대N2、CO2적흡부량，병개전삼축압축역학실험정량연구료N2、CO2흡부대매암역학강도적영향；분석료매암중렬문확전궤리，근거단렬역학이론추도출함기매암중적렬문확전속도방정，병근거방정계산출주불동기체시매암중적렬문확전속도。연구표명，재상동평형압력하，매암대CO2적흡부량시CH4적6배；매암포화CO2후적역학강도명현저우포화N2적역학강도；매층주CO2비주N2인기적렬문확전속도경대，병차주기압력월고확전속도월대。해이론성과능구위우화주기적비례급주기압력제공이론지도，병차대방지매층실은，보장순리주기구유중요의의。
N2 or CO2 is commonly injected into coal seam to enhance CBM recovery or realize CO2 storage. The injected gas will make crack growth occur in coal seam, which can induce instability. Taking the No. 9 coal seam in Ningwu basin as the research object, ifrstly, the isothermal adsorption experiment was carried out to study the adsorption capacity of coal rock for N2 and CO2 quantitatively and tri-axial compression mechanics experiment was carried out to study the inlfuence of N2 and CO2 adsorption on the mechanical strength of coal rock. The mechanism of crack propagation was analyzed and the crack propagation speed equation of coal seam containing gas was deduced according to the theory of fracture mechanics and, according to the equation, the crack propagation speed was calculated when different gases were injected. Studies show that the adsorption of coal rock for CO2 is six times larger than CH4 under the same equilibrium pressure, the mechanical strength of coal rock saturated by CO2 is signiifcantly lower than that of N2, The crack propagation speed of coal with CO2 injection is much bigger than that of N2, and the greater the gas injection pressure is, the higher the propagation speed will be. This theoretical result can not only provide a guidance for optimizing the proportion of gas injection and gas injection pressure, but also is of great signiifcance to prevent the instability of coal bed and ensure gas injection smoothly.