探讨CO2注入深煤层提高煤层气采收率可行性对于解放我国丰富深部煤层气资源具有积极意义。分析了沁水盆地不同深度条件下储层参数的变化规律,开展了CO2注入煤层增产效应的数值模拟研究。结果显示,煤储层参数随埋深呈非线性变化且各参数显著变化深度具有较好的对应性,存在500~600 m,950~1 150 m两个关键转折界限,据此将煤层划分为浅部、过渡、深部三带。随着埋深增加煤储层强非均质向均质转换,即所有参数在浅部较为离散而深部收敛。通过不同深度煤层的CO2注入生产效果模拟显示,注入CO2后煤层气采收率均得到不同幅度提高;注入CO2提高煤层气采收率效果由过渡带、浅部、深部逐步递减;注入时间越早和越长,提高采收率效果越显著;要实现深部煤层气采收率显著增加必须保证一定的CO2注入量;深部CO2封存优势显著。

Feasibility analysis of enhanced coalbed methane recovery by CO2 sequestration is important for the develop- ment of abundant deep coalbed methane resource in China. In this study,the relationships between reservoir parame- ters and burial depth were analyzed,and the simulation on CO2 sequestration into coal were carried out. The results show that reservoir parameters vary nonlinearly with the increase of burial depth and their transition burial depths are close. The coalbed in Qinshui Basin are divided into shallow,transition and deep part according to two key proposed transition burial depth of 500-600 m and 950-1 150 m. Strongly heterogeneous of reservoir parameters in shallow coal seams transform into homogeneous in deep coal seams. Through the contrasting simulations of CO2 sequestration into different burial depth coal seams,the coalbed methane recoveries are enhanced in all the cases,and the increments of coalbed methane recovery comparing with none injection decrease in the order of transition,shallow and deep coal seams. More early and longer injection time have higher improvement on coalbed methane recovery. To achieve an ob- vious coalbed methane recovery,a certain amount of CO2 should be sequestrated into coal seams. Deep coalbed has higher CO2 storage capacity than shallow and transition part coal seams.