CO2强化煤层气产出与其同步封存实验研究

长期以来针对CO₂-ECBM已做了大量研究工作,然而有限的工业试验没能达到预期目的,使得这一煤层气强化技术推广应用欠缺。近些年随着各国碳中和路线的制定,CO₂封存逐渐受到重视,煤储层可否作为CO₂的封存空间、可否实现CO₂驱替CH₄和封存同步进行,又重新回归人们的视野。为此,以新疆准南区块目标煤层样为研究对象,采用不同CO₂与CH₄混合比例气体进行煤的吸附/解吸实验,探索混合气体比例对CO₂-ECBM和CO₂吸附封存潜力的影响。结果表明,随着混合气体CO₂比例减少,CH₄驱替效果降低,其中40%CH₄+60%CO₂混合气体的CO₂残余量最多,在解吸至0.7 MPa时已有83.05%的CH₄产出,而83.62%的CO₂吸附残余在煤中,表明其C...

Experimental study on CO2-enhanced coalbed methane production and its simultaneous storage

Abstract: Experimental study on CO₂-enhanced coalbed methane production and its simultaneous storage Abstract: For a long time, a lot of work has been done on CO₂-enhanced coalbed methane (CO₂-ECBM), but the limited industrial trials failed to achieve the expected purpose, which prevented the promotion and application of CBM enhancement technology. In recent years, with the establishment of carbon neutrality routes in different countries, CO₂ geological storage has gradually gained attention, and the questions of whether coal reservoirs can be treated as CO₂ storage space and whether simultaneous CO₂ displacing CH₄ and storage can be achieved have returned to the spotlight. In this study, using the coal samples from Xinjiang Zhunnan coal region, the adsorption/desorption experiments of coal were carried out with different mixture ratios of CO₂ and CH₄ to explore the effects of gas composition on CO₂-ECBM, as well as CO₂ adsorptive storage potential. The results show that, the CH₄ displacement effect decreases as the CO₂ ratio of the mixed gas decreasing, among which the CO₂ residual volume of 40% CH₄+60% CO₂ mixture is the highest, corresponding to 83.05% CH₄ production and 83.62% CO₂ storage by adsorption as the experimental pressure drops to 0.7 MPa during desorption processes. This indicates that its CO₂ adsorptive storage potential is the best. The desorption volume and rate of each mixed gas during different depressurization and desorption stages were calculated according to the Dalton’s law for partial pressure and partial volume, as well as the Langmuir’s equation. The results indicate that, as the CO₂ ratio of the mixed gas decreases, the CO₂ residual rate and volume, as well as the final CH₄ desorption rate, were decrease. The predicted trends of CH₄ desorption rate and CO₂ residual volume with gas mixture composition are generally consistent with those obtained by the experiments, indicating that high proportion of CO₂ in the gas mixture enhances CH₄ recovery, as well as CO₂ adsorptive storage potential of the coal reservoir. This study can provide not only theoretical basis for the field application of CO₂-ECBM and CO₂ storage, but also experimental supports for the promotion of this technology.