阜新煤田注二氧化碳提高煤层甲烷的研究

Preliminary study on coal bed methane displacement with carbon dioxide injection in Fuxin Coalfields

针对阜新煤田煤储层的地质特征,选取了刘家煤层气勘探区和东梁矿2个地点,开展了注二氧化碳置换煤层甲烷的试验模拟研究。试验结果表明,二氧化碳的吸附能高于甲烷的吸附能,它可以将甲烷从煤的微表面置换出来,从而提高煤层甲烷的采出率。在置换过程中总是吸附能力弱的甲烷首先解吸,而吸附能力强的二氧化碳最后解吸,而且较高压力下的置换效果总比低压下的好。与东梁矿煤样相比,刘家煤样具有较强的吸附能力和较高的单位压降下的解吸率,但置换效率相差不大,主要原因是二者的二氧化碳对甲烷分离因子差别较小。注气试验时应该充分考虑注入压力点和气体注入量才能保证满意的置换效果。

Based on the reservoir geological characteristics in Fuxin Coalfield, Liujia CBM pilot-test area and Dongliang mine were selected and a preliminary laboratory experiment on coal bed methane （CBM） displacement with carbon dioxide injection was conducted. The results showed that due to the adsorption capacity of CO2 higher than CH4 , CH4 can be displaced by CO2 from the surface of the coal. Therefore the methane recovery rate can be improved. During the displacement, the low adsorption methane was always first to be desorbed and the high adsorption CO2 was late to be desorbed. The displacement results under the high pressure is always better than the low pressure. In comparing with Dongliang, the Liujia coal samples had a higher absorption capacity and a high unit pressure drop desorption ratio. But there was no big difference between the two in the displacement rate. The main causes are that the difference in the separatefactor of CO2vs CH4 was negligible between two samples. During the air injection period, it shall fully consider the injected pressure and the injected quantity in order to have a satisfied displaced result.