Mass transfer study on CO₂ penetration through methane hydrates using CO₂ vapor and a CO₂ nucleated micro-emulsion

Abstract

Gas hydrates are solid inclusion compounds that are made up of ice and large amounts of guest gas molecules. Due to their abundance in nature and the ability to entrap large amounts of natural gas, progress towards tapping this energy resource is on the forefront of research. Much research on the kinetics of formation and decomposition needs to be completed. This study was comprised of the identification of CH₄ and CO₂ through their characteristic Peak Raman shifts, the determination of the mass transfer rates of CO₂ through pre-formed methane hydrate, and an experimental injectant using a dissociated CO₂ micro-emulsion to help destabilize the CH₄ hydrate zone. Identification experiments showed that characteristic peak locations were instrument dependent and that O-H stretch analysis could help in the determination of the phase gas was in. Mass transfer rates were obtained for CO₂ penetration through methane hydrates by a headspace swap in an associated free gas zone. Experimental temperatures of the hydrate zone were 0, 2.5, and 4.5°C. Results indicate that CO₂ can penetrate into CH₄ hydrate zone by dissociating the CH4 from a hydrate phase and stabilizing the mixed CO₂-CH₄ hydrates. The process is slow in the magnitude of 10⁻⁸ meters per second.