抽采瓦斯过程中煤层温度演化规律的物理模拟试验研究

 煤层瓦斯作为一种非常规天然气，对其进行开发利用具有一举多得的功效，越来越受到各国重视。为了研究煤层瓦斯解吸过程中煤层温度的演化规律，利用自主研发的多场耦合煤层气开采物理模拟试验系统，开展了不同初始瓦斯压力和不同地应力水平下抽采瓦斯的物理模拟试验。研究结果表明：(1) 煤层瓦斯解吸吸热导致煤层温度下降，且温度和流量具有很好的相关性，都表现出在抽采初期下降较快，后期下降缓慢，其中温度随时间的下降量符合对数函数关系；(2) 距抽采钻孔越近，瓦斯解吸速度及温度下降越快、温度下降量越大，且垂直钻孔方向的温度梯度大于平行钻孔方向的温度梯度；(3) 初始瓦斯压力越大，瓦斯解吸速度及煤层温度下降越快、温度下降量越大，而地应力越大，瓦斯解吸速度及温度下降越慢、温度下降量越小，表明初始瓦斯压力对解吸过程中煤层温度的影响效果较地应力更加显著。

PHYSICAL SIMULATION EXPERIMENT ON THE EVOLUTION OF TEMPERATURE DURING CBM DRAINAGE

Coal-bed methane (CBM) is an unconventional gas，its exploitation has fully staffed effect and gets more and more national attention. In order to research the evolution of temperature during gas desorption，the physical simulation of CBM drainage under different gas pressure and in-situ stress was determined based on self-developed multi-field coupling test system for CBM drainage. The results showed as follows：(1) During the drainage process，the coal seam temperature decreased because of gas desorption. As a result，temperature and flow had close correlation，which showed that they decreased rapidly in the early stage，and then declined steadily after a period of drainage. Relationships between temperature dropping and time were logarithmic regression；(2) The closer to the borehole the faster temperature dropped at the same time，the temperature gradient of vertical plane was greater than horizontal plane；(3) The larger the gas pressure，the faster temperature dropped and the greater amount it dropped，while the larger in-situ stress and the slower temperature dropped，the smaller amount it dropped. It can be concluded that the effect of temperature on gas pressure was more significant during gas desorption.