Energy & Fuels, Vol.34, No.4, 4106-4115, 2020
Pore Characterization and Inner Adsorption Mechanism Investigation for Methane in Organic and Inorganic Matters of Shale
The pore characterization and the adsorption property for gas shale have been studied widely due to the vigorous exploration of shale gas reservoirs. However, for a particular shale sample, few research studies have focused on the pore characterizations and inner adsorption mechanisms for different types of pores in organic and inorganic matters. In this research, a low-pressure N-2/CO2 adsorption method with a novel analysis and a simplified local density (SLD) method with a particular regression were utilized to investigate the pore characteristics and inner adsorption mechanisms for methane in organic micropores and inorganic micropores and nonmicropores. Effective pore characterizations were acquired for these three types of pores. Furthermore, based on the obtained adsorption proportion of each type of pore to the total adsorption of all the pores, the adsorptions in inorganic micropores and nonmicropores were both essential and nonnegligible. Organic micropores are more competitive than inorganic micropores for adsorption owing to their stronger fluid-wall interaction. Due to the variation in density distribution in the pores, excess adsorption possesses positive and negative relationships with micropore size at high and low pressures, respectively, and slightly negative relationship with nonmicropore size. Besides, strong solid-solid molecule interactions and small pores could bring about a high sensitivity of adsorption to the specific surface area (SSA).