【目的】增加煤储层渗透性是提高煤层气采收率的关键技术,原位注热开采是强化煤层气开采的有效方法。【方法】为了探索热流固耦合作用下煤储层渗透率的变化规律,进行了不同埋深不同温度无烟煤渗流试验,并对结果进行理论分析研究。【结果】1)三维有效应力作用下,无烟煤渗透率随温度和孔隙压力的变化呈“V”形,具有明显的回弹现象,随埋深的增加而减小。当孔隙压力小于临界孔隙压力,温度小于70℃时,煤体渗透性主要取决于滑脱效应。当孔隙压力大于临界孔隙压力,温度大于70℃时渗透性主要取决于热膨胀和孔隙压力对裂隙的张开程度,热刺激对渗透率的影响远大于孔隙压力。2)临界孔隙压力介于1~1.5MPa之间,滑脱效应随温度的升高对渗透率的影响在逐渐减小,而且影响减小的梯度随埋深的增加而增大。3)裂隙张开度系数随温度升高和埋深增加而增加,但温度越高,不同埋深下渗透性对孔隙压力作用的敏感程度变化越小。【结论】这些研究结果进一步丰富了原位注热开采煤层气理论,并对煤层气的强化增渗开采提供有价值的参考数据。

【Purposes】Increasing the permeability of coal reservoirs is a key technology to improve the recovery rate of coalbed methane, and in-situ thermal injection mining is an effective method to en-hance coalbed methane production.【Methods】In order to explore the change rule of coal reservoir permea-bility under the coupling of heat, fluid, and solid, pyrolysis seepage experiments of anthracite with differ-ent burial depths and temperatures were conducted, and theoretical analysis and research were conducted on the experimental results.【Findings】The results showed that: 1) Under three-dimensional effective stress, the permeability of pyrolysis anthracite varies with temperature and pore pressure in a "V" shape, with a significant rebound phenomenon, which decreases with the increase of burial depth.  When the pore pressure is less than the critical pore pressure and the temperature is lower than 70 ℃, the permeability of the coal body mainly depends on the slippage effect.  When the pore pressure is greater than the critical pore pressure and the temperature is higher than 70 ℃, the permeability mainly depends on thermal expan-sion and the opening degree of pore pressure on the fracture, and the impact of thermal stimulation on the permeability is much greater than that of pore pressure.  2) The critical pore pressure is between 1 and 1. 5 MPa, the influence of slippage effect on permeability gradually decreases with the increase of tempera-ture, and the gradient of influence reduction increases with the increase of burial depth.  3) The fracture opening coefficient increases with the increase of temperature and burial depth, but the higher the tempera-ture, the smaller the change in the sensitivity of permeability to pore pressure under different burial depths.  【Conclusions】These research results further enrich the theory of in-situ thermal injection mining of coal-bed methane, and provide valuable data reference for enhanced permeability of coalbed methane.