页岩气与煤层气吸附/解吸热力学特征对比
Comparison on adsorption and desorption thermodynamics features between shale gas and coalbed methane
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摘要: 为了促进煤层气与页岩气在储层评价与开发方式选择上的相互借鉴,进行了煤与页岩吸附甲烷的对比试验。通过多温度点页岩气和煤层气吸附/解吸试验,计算升压过程与解吸过程吸附热差异,发现热演化程度基本一致时,极限吸附热计算结果表明:煤层气在升压吸附时放热量19.148k J/mol,小于降压过程吸热量23.966 k J/mol,降压解吸难以持续;页岩气在升压吸附时放热量44.624k J/mol,大于降压过程吸热量32.656 k J/mol,降压促进吸附/解吸平衡向解吸方向移动。因此,利用排水降压进行煤层气开采时,应重视持续解吸技术的研究。Abstract: In order to promote the reservoir assessment of coalbed methane and shale gas ,and the mutual reference of their development modes,a comparative experi ment was conducted on coal and shale absorbing methane. With multi temperature points shale gas and coalbed methane adsorption and desorption test,the adsorption he at difference during the pressure increasing process and desorption process was calculated. When the thermal evolution degrees were basically the same,the calculate res ults of the limit adsorption heat showed that during the pressure increasing and adsorption period,the 19.148 k J 1 mol heat released value of the coalbed methane during t he pressure increasing and adsorption period would be less than 23.966 k J 1 mol absorbed heat value during the pressure declining process. The pressure declining desor ption would be hard to be sustainable. During the pressure increased adsorption period,44. 624 k J 1 mol heat released value of the shale gas would be higher than the 32. 656 k J 1 mol absorbed heat value during the pressure declining process.The pressure declining could promote the adsorption and desorption moving forward to the desorp tion direction in balance. Therefore,when the water drainage and pressure declining was applied to the coalbed methane mining,the study on the continuous desorption tech nology should be highly concerned.