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如何提高煤层气采收率是目前煤层气开发的重点课题。通过实验揭示了温度是影响煤层气渗透率及解吸渗流量的关键因素之一,得到了非等温条件下煤层气解吸-渗流规律。实验通过自制的温控三轴煤层气解吸渗透仪进行规律探究。经数据拟合,分析得出:不同温度条件下,渗透率随孔隙压力的增加以指数形式递增;在相同围压、轴压和孔隙压力条件下,等温解吸时,煤样瓦斯渗流量随温度的增加而呈现指数递减规律;升温解吸时,解吸量比低温下的渗流量增加,孔隙压力越大,渗流量增加越明显。根据试验结果,认为在注热开采煤层气时,通过间歇式注热(蒸汽吞吐)使煤层温度梯度不断变化,煤层发生升温解吸,有利于煤层气的产出。对低渗透煤层瓦斯开采提出新的思路。
How to improve CBM recovery rate is the key issue of CBM development at present. Experiments show that the temperature is one of the key factors that affect CBM permeability and desorbed seepage flux. The desorption-seepage law of CBM under non-isothermal condition is obtained. The experiments were conducted by self-made temperature controlled triaxial coalbed methane desorption and permeation apparatus. Through data fitting, the analysis shows that under different temperature conditions, the permeability increases exponentially with the increase of pore pressure. Under isothermal desorption under the same confining pressure, axial pressure and pore pressure, The descending rate of desorption is higher than that of low temperature, and the larger the pore pressure is, the more obvious the increase of seepage will be. According to the test results, it is considered that when the coal seam gas is extracted by heat injection, the temperature gradient of the coal seam continuously changes through intermittent heat injection (steam huff and puff), and the coal seam heats up and desorbs, which is in favor of the output of coalbed methane. Propose new ideas for gas production in low permeability coal seam.