煤层处置二氧化碳模拟实验研究

Simulation experiment of carbon dioxide storage in coal seam

为了研究CO2在煤层中的储存能力与置换驱替CH4特性,利用沁水煤田潞安矿区3号煤层大尺寸(100 mm×100 mm×200 mm)煤样,在确定应力约束条件下,开展了CO2在煤体中的吸附特性与其在含甲烷煤试样中的驱替实验,并对含甲烷煤和不含甲烷煤中CO2的储存特性做了对比分析。结果表明:在模拟真实地应力(围压=轴压=8 MPa)条件与0.5 MPa注入压力作用下,180min内试验煤样中储存CO2量达11.03 L,CO2在测试煤体中的渗透率随其吸附量的增加而减小;在既定的地应力条件和近于14.93 cm3/g煤层平均瓦斯含量条件下,当CO2注入压力由0.5 MPa提高到1.0 MPa时,CO2在试验煤体中的储存量可提高93.00%、储存率提高13.50%、相应CH4的解吸量提高了18.13%;在实验初期,CH4的解吸量高于CO2的吸附量,随注入过程的持续,煤体中CH4的解吸量逐渐趋于平缓且远小于CO2的吸附量;同等条件下,含CH4煤比不含CH4煤可多储存59.29%的CO2,储存率提高了12.51%。

In order to study the capacity of CO2 storage in coal bed and the displacement of methane CH4 in coal by CO2 injection, an experiment about the CO2 adsorption and coalbed methane（CBM） replacement in coal under given pressure was carried out with coal specimens of large size（ 100 mm× 100 mm×200 mm） from the No. 3 coal seam, Qin- shui Basin, China. Based on the experiment, the CO2 storage capacity difference between coal containing CH4 and coal without CH4 was contrastively analyzed. The experimental results demonstrate that, the storage of CO2 in the coal speci- men can amount to 11.03 L under the in-situ stress condition of the coal bed and injection pressure of 0.5 MPa. CO2 permeability through the coal decreases with the increase of its adsorption amount during the experiment duration of 180 min. When the CO2 injection pressure increases to 1.0 MPa from 0.5 MPa under the same confining stresses,the CO2 storage amount in the coal increases by 93.00%, the storage rate increases by 13.50% and the amount of CH4 desorption increases by 18.13%. It is found that the amount of CH4 desorption is larger than CO2 adsorption in the ini- tial experimental stage. After that, the amount of CH4 desorption tends to be stable but far less than CO2 adsorption amount. Under the similar experimental condition, the CO2 storage capacity in coal containing CH4 is 59.29% more than that of coal without CH4 ,and the storage rate in coal containing CH4 increases by 12. 51% compared that in coal without CH4.