不同状态CO2驱替页岩吸附CH4的动态特性研究

Study on dynamic characteristics about the displacement of adsorbed CH4 on shale by injecting different states of CO2

为了研究不同状态CO2驱替页岩吸附CH4的动态特性,以鄂尔多斯盆地陆相延长组页岩为研究对象,开展了不同状态CO2驱替页岩吸附CH4的柱动态学实验,并采用Coats-Smith两区模型模拟了储层内CO2驱替吸附CH4的动态过程。研究结果表明:随着CO2注入压力的提高,穿透曲线的拖尾现象更加明显,实验初期流出的纯CH4的量逐渐降低且CO2的封存量逐渐增大;当CO2注入压力为8.0 MPa时,不同温度下的穿透曲线不重合,超临界态CO2更容易扩散进入不可动区内去置换吸附的CH4;液态和超临界态CO2在页岩上的吸附性强于气态CO2。

In order to study the dynamics of the displacement of adsorbed CH4 on shale by injecting different states of CO2,the continental Yanchang formation shale in Ordos basin were chosen as research object.Coats-Smith dispersion-capacitance model was used to simulate the migration of CO2 in the reservoir during injecting CO2 into shale preadsorbed by CH4.Experimental results show that,as the CO2 injection pressure increases,the amount of pure CH4 at the beginning of the experiment gradually decreases,the tailing phenomenon of the breakthrough curves become more obvious and CO2 storage increases.When the injection pressure of CO2 is 8.0 MPa,the breakthrough curves at different temperatures are not coincident.Supercritical CO2 is more likely to enter the stagnant region to replace adsorbed CH4.The adsorption of gaseous CO2 is weak,and the adsorption of liquid and supercritical CO2 is stronger on shale.