CO_2分子置换法开采页岩气实验

Experimental study on CO_2 replacement method used in shale gas exploration

从CO2置换页岩气吸附气开采机理入手,通过页岩等温吸附、直接降压解析、注CO2置换解析实验评价方法,探讨利用CO2分子置换页岩气吸附气提高采收率的方法。实验结果表明,富县页岩注CO2置换法开采页岩气比直接降压开采的采收率提高了7.66%,地层压力衰竭到6.559 MPa时,注CO2效果最好,最佳的CO2注入量为0.22倍的孔隙体积。注CO2分子置换法开采页岩气是可行的,不仅能提高页岩气的采收率,而且可以缩短开采周期。

This paper approaches a new method to promote the recovery by using CO2 to take the place of adsorption shale gas. The method proceeds from the perspective of exploitation mechanism of CO~ molecular replacement, by means of experiment evaluation methods of shale adsorption isotherms, direct depressurization and desorption, desorption by injecting CO2 replacement. The experiment results in labs of Fuxian suggest that the recovery by injecting CO2 increases by 7.66 % and is higher than that by the way of direct depressurization and desorption. It is more suitable to inject CO2 when the reservoir pressure exhausts to 6. 559 MPa, and the proper volume of the injecting CO2 is 0.22 times its pore volume. The CO2 molecular replacement method is feasible. It can improve the shale gas recovery and shorten the exploration cycle.