注入CO2提高煤层气产能的可行性研究

根据煤储层吸附一解吸机理，首次采用“解吸一注气一解吸”的实验方法，分别进行CH4，CO2的吸附一解吸和CO2注入置换煤层CH4实验，模拟了煤层气井“排采一注气一排采”的增产途径和效果。结果表明：在CH4和CO2二元体系的竞争吸附中，CO2组分的吸附速率是先快后慢，而CH4组分的吸附速率先慢后快，解吸时则相反，反映出CO2在竞争吸附中占据优势；注入CO2气体的数量越大和相对浓度越高，单位压降CH4解吸率和CO2吸附率就越高。实验结论对工业规模的煤层气开发试验具有指导意义。

A Feasibility Study on CO2 Injection for Enhancing the Coalbed Methane Recovery

The adsorption-desorption behavior of carbon dioxide and methane gases in coal samples were experimentally studied. The replacement experiments of methane by carbon dioxide for simulating the process of "CH_4 production-CO_2-injection-CH_4 production" were also made in order to enhance the coalbed methane recovery. The CO_2 and CH_4 composition variation and phase separation curves were obtained. The results show that with the proceeding time of experiments, the competition rate of adsorption for CO_2 decreases, while that for CH_4 increases. However, the reverse results were obtained for competition rate of desorption for these gas phases. It indicates that the adsorption of CO_2 is prior to that of CH_4. If the amount of injected CO_2 and/or the CO_2 concentration is higher, the rate of CH_4 desorption and CO_2 adsorption would be higher. The results of our experiments are significant to commercial production of coalbed methane.