Integrating NMR-Based Data with Theoretical Adsorption Models in Methane-Shale Systems

Understanding the gas sorption behavior is essential to accurately assess reservoir potential and optimize production strategies for these resources. Adsorption experiments are commonly employed to assess a rock's gas adsorption capacity. Adsorption isotherms quantify the relationship between gas absorbed onto a rock surface and the associated equilibrium conditions. This study focuses on investigating methane (CH₄) adsorption on shale under varying pressure and temperature conditions. The objective is to provide a theoretical analysis of methane adsorption on shale using representative models to evaluate the applicability of adsorption isotherms. Specifically, we utilized a modelling approach to assess the applicability of Langmuir and BET isotherms frameworks to a methane/shale system based on published NMR adsorption data. This research is novel in that it examines the predictive capabilities of established gas adsorption isotherms for NMR experimental methane/shale adsorption data, particularly considering pressures up to 150 bar and at 297 K. A significant challenge in unconventional reservoirs lies in the absence of a thorough comprehension of storage mechanisms and the complex characteristics of the formations. The findings will enhance our understanding of these isotherms' predictive abilities and supply essential numerical variables for modelling methane shale systems at a reservoir scale. This will aid in history matching and enable predictions of formation behavior.