Investigation of the Methane Adsorption Characteristics of Marine Shale: A Case Study of Lower Cambrian Qiongzhusi Shale in Eastern Yunnan Province, South China

Abstract

Marine organic-rich shale in South China has considerable exploration potential, and the shale adsorption capacity has a great impact on the accumulation of shale gas. To study the methane adsorption capacity of marine shale, ten shale samples from the Lower Cambrian Qiongzhusi Formation in eastern Yunnan province were investigated by organic geochemical analysis (total organic carbon content, thermal maturity, and kerogen type), X-ray diffraction (XRD) analysis, field emission scanning electron microscopy (FE-SEM), and low-pressure nitrogen adsorption and methane adsorption experiments. Based on the different adsorption mechanisms of various pores, the Dubinin–Radushkevich and Langmuir–Freundlich models were used to construct a supercritical adsorption model of shale. Combined with this model, the mechanisms and characteristics of shale adsorption under supercritical conditions were analyzed. The maximum absolute methane adsorption capacities of micropores (V1) and mesopores-macropores (V2) were also cal...