Effect of Multicomponent Adsorption/Desorption Behavior on Gas-In-Place (GIP) Calculations and Estimation of Free and Adsorbed CH4 and CO2 in Shale Gas Systems

Abstract

Abstract Unconventional shale gas resources have become a major component of the energy mix in North America, with future growth projected globally. The nature of storage and transport of hydrocarbon gas are not yet fully understood in these plays. Adsorption in gas shales is expressed by the Langmuir isotherm, which is the capacity of the rock to adsorb gas at any given temperature. The Langmuir isotherm is generally measured in the laboratory with crushed rock samples. In the presence of CO2 with CH4 in the free gas state, the desorption behavior and measurement becomes more complex. There are significant differences in sorption experimental procedures and results reported by different vendors. This study addresses the challenges in data variability in sorption measurement, the differences in EUR and GIP calculations, including existing limitations on adsorption measurement and reporting techniques. The results and implications of round- robin experiments with four different samples across four vendor laboratories are shown with multi-component adsorption isotherm analysis. The limitations and variations based on vendor data measurement techniques for accurately calculating GIP and EUR in the case of multi-component adsorption are discussed.