摘要
Abstract
In order to investigate the effect of temperature conditions on CO2-ECBM(CO2-enhanced coalbed methane),this study constructed a fully coupled model of CO2-ECBM considering the non-isothermal adsorption effect based on the theories of adsorp-tion thermodynamics and seepage mechanics,and systematically investigated the effect of different temperature conditions on the dy-namic evolution of multi-physical fields in the CO2-ECBM process.The results show that the desorption of CH4 and adsorption of CO2 in the CO2-ECBM process are adsorptive and exothermic reactions,respectively,which will lead to significant changes in the temperature of the coal reservoir.With the extension of injection time,the coal reservoir temperature can be divided into four stages:slight decrease,sharp increase,sharp decrease and gradual stabilization,and the extension of injection time will lead to the gradual expansion of the temperature anomaly region in the coal reservoir.At the same time,the change of coal reservoir permeability is af-fected by the contraction/expansion of coal matrix due to gas desorption/adsorption and thermal expansion which compete with each other to determine the final evolution of coal reservoir permeability.In the area where CO2 has not yet infiltrated into the coal reser-voir,the contraction of the coal matrix due to CH4 desorption dominates the evolution of the permeability of the coal reservoir,and the injection temperature is positively correlated with the permeability of the coal reservoir,while the initial temperature of the coal reservoir is negatively correlated with the permeability.After the intersection of CO2 and CH4 in the coal reservoir,the permeability of the coal reservoir is dominated by the net effect of gas competition adsorption and thermal expansion,and the relationship between the injection temperature and the permeability of the coal reservoir changes to a negative correlation,while the relationship between the initial temperature of the coal reservoir and the permeability changes to a positive correlation.In addition,the increase of injec-tion temperature can effectively improve the CH4 production efficiency and CO2 storage efficiency,while the increase of initial tem-perature of coal reservoir can reduce the CH4 production efficiency and CO2 storage efficiency.关键词
煤层气开采/竞争吸附/热效应/CO2封存/数值模拟Key words
coalbed methane extraction/competitive adsorption/thermal effect/CO2 sequestration/numerical simulation分类
矿业与冶金
