Determination of the absolute CH adsorption using simplified local density theory and comparison with the modified Langmuir adsorption model

• Published in: RSC advances 2018-12, Vol.8 (72), p.4159-41516
• Main Authors: Zhang, Yeyu, Zhang, Shaonan, Wang, Zhicheng, Deng, Hucheng, Qi, Minghui, Peng, Xianfeng, Liu, Yueliang
• Format: Article
• ISSN: 2046-2069
• DOI: 10.1039/c8ra08586b

Accurately determining the adsorbed amount of CH 4 on shale is significant for understanding the mechanisms of shale gas storage and shale methane recovery from shale gas reservoirs. Excess CH 4 adsorption is measured using the thermogravimetric method. Simplified local density (SLD) theory is applied to calculate the adsorbed CH 4 density to obtain the absolute adsorption. Moreover, the modified Langmuir adsorption model is employed to fit the excess adsorption to describe the absolute adsorption. The adsorbed CH 4 density from the SLD model is affected by the system pressure and temperature, while such density obtained from the modified Langmuir model is only a function of temperature. Compared to the modified Langmuir model, the SLD model can better capture the adsorbed CH 4 density, which allows accurate determination of the absolute CH 4 adsorption. Accurately determining the adsorbed amount of CH 4 on shale is significant for understanding the mechanisms of shale gas storage and shale methane recovery from shale gas reservoirs.