混合气体驱替煤层气技术的可行性研究

气体驱替煤层气技术是近年来发展起来的具有温室气体减排和提高煤层气采收率双赢效果的新兴技术,相关研究受到世界主要发达国家的广泛重视。对于温室气体减排的压力,发达国家的研究主要着眼于该技术在高渗透、不可采煤层中的应用,注入气体主要为CO2,目的是尽可能多地封存CO2,同时提高煤层气采收率。目前,国内在这方面的研究刚刚起步。国内煤层具有渗透率普遍较低、不开采煤层与要开采煤层难以界定的特点,注CO2气体驱替煤层气在这种煤层中的可行性值得商榷。针对国内煤层特点和煤矿瓦斯抽采率低的现状,建议采用富N2混合气体驱替煤层气技术,以提高煤层气产采收率。通过理论分析、数值模拟和现场试验研究分析了实施混合气体驱替煤层气技术的可行性。研究结果表明,混合气体驱替煤层气技术适用于国内低渗透、可开采煤层,可以提高煤层气采收率和单产量。

Feasibility study of gas mixture enhanced coalbed methane recovery technology

Gas enhanced coalbed methane recovery technology (ECBM), which has the win-win effects on reducing the greenhouse gas emissions and improving coalbed methane recovery ratio, is an emerging technology in recent years. Related research of ECBM has been paid the extensive attentions by major developed countries. Because of the pressure from greenhouse gas emissions reduction, up to now, the developed countries are focusing on studying the application of CO2-ECBM technology in high permeability and unminable coal, for the purpose of permanently storing CO2 as more as possible and enhancing CBM recovery ratio at the same time. Currently, research of this aspect is started just now in China. Most coal in China has the characteristics of low permeability and it is difficult to define unminable coal or minable coal, so it is questionable to apply CO2-ECBM in these coalbed. In view of the characteristics of coal and the present situation of coal mine gas drainage in China, the gas mixture enhanced coalbed methane (G-ECBM) technology has been suggested for the purpose of enhancing coalbed methane recovery ratio. The feasibility of G-ECBM in China has been analyzed by theoretical analysis, numerical simulation and field test study. The results show that G-ECBM technology is applicable to the low permeability and minable coal in China; and it can enhance the coalbed methane recovery ratio and single well production.