Supercritical high-pressure methane adsorption on the lower cambrian Shuijingtuo Shale in the Huangling Anticline Area, South China: Adsorption behavior, storage characteristics, and geological implications
Energy & Fuels
School of Engineering / Centre for Sustainable Energy and Resources
National Natural Science Foundation of China
National Science and Technology Major Project of China
China Geological Survey
Programme of Introducing Talents of Discipline to Universities
Supercritical high-pressure methane (CH4) adsorption analysis was performed to investigate the gas adsorption behavior and storage capacities of the Lower Cambrian Shuijingtuo Shale in the Huangling anticline area, South China. The parabolic-like shapes of the excess isotherms are ascribed to the relative increasing rate of the adsorbed gas density (∂ρads/∂P) and free gas density (∂ρfree/∂P). The maximum value occurs where the ∂ρads/∂P value is equal to that of the ∂ρfree/∂P value. The adsorption phase volumes (Vads) are approximately equal to the Dubinin–Radushkevich (DR) micropore volumes (VmicroP) but much lower than the Barrett–Joyner–Halenda (BJH) total pore volumes (VtotalP). Such a volume-sequence indicates that methane (CH4) molecules are preferentially filled in micropores and then adsorb on meso-/macropores. The strong positive relationship between the total organic carbon (TOC) content and the methane (CH4) adsorption capacity is the result of the abundant nanoscale organic matter (OM) pores, which can provide significant adsorption sites and space. The gas content calculated by burial depth shows that the shale gas at the burial depth of the Shuijingtuo Shale is mainly composed of adsorbed gas. The pore pressure can significantly increase the total gas content (TGC) and free gas content (FGC) but has a limited influence on the adsorbed gas content (AGC), indicating that at the initial gas development, free gas is the predominantly produced gas. Moreover, these findings further indicate that the operating pressure should be kept as low as possible to allow the adsorbed gas to be released from the shale matrix to improve shale gas recovery.
Wei, S., He, S., Hu, M., Yang, W., Guo, X., Iglauer, S., & Zhai, G. (2021). Supercritical high-pressure methane adsorption on the lower cambrian Shuijingtuo Shale in the Huangling Anticline Area, South China: Adsorption behavior, storage characteristics, and geological implications. Energy & Fuels, 35(24), 19973-19985.