川东龙马溪组页岩解吸滞后现象实验研究

Experimental Study on Desorption Hysteresis of Longmaxi Formation Shale in Eastern Sichuan

为了明确页岩气在大压力下的解吸滞后现象以及解吸滞后的影响因素,利用取自川东龙马溪组页岩露头的样品,进行页岩物性测试和吸附-解吸附实验测试。实验结果表明,页岩与甲烷的气固吸附和解吸附等温线不重合,存在明显的吸附滞后现象,且解吸滞后程度与页岩物性参数有关,页岩物性越差,孔隙结构越复杂,解吸滞后环越大。同时应用3种吸附理论模型对实测吸附和解吸附量数据进行拟合,拟合结果表明,相对于Langmuir方程和Freundlich方程,Langmuir-Freundlich方程能够更好地描述页岩气的吸附和解吸附特征。

The physical property and adsorption-desorption performance of the outcrop samples of Longmaxi Formation shale in eastern Sichuan were tested in order to understand the desorption hysteresis of shale gas in large pressure range and its influencing factors. The experimental results show that,the adsorption and desorption isotherms of methane to shale do not coincide,and there is desorption hysteresis. The desorption hysteresis is related to the physical parameters of shale,and the worse the physical property of shale,the more complex the pore structure of the shale,the larger the desorption hysteresis loop. The measured adsorption and desorption data of the shale samples were fitted using three kinds of adsorption models,the fitting results show that,compared with Langmuir equation and Freundlich equation,Langmuir-Freundlich equation can better describe the adsorption-desorption characteristics of the shale gas.