(74a) Electrical Resistance Measurement during CH4-CO2 Mixed Hydrate Formation and Dissociation in Sandstone

A better understanding of formation, dissociation and stability of CH₄ gas hydrate and CO₂ gas hydrate in porous medium via electrical resistance measurement is essential to understand the physical process taking place during the CO₂ injection into the CH₄ hydrate system that results in CH₄-CO₂ mixed hydrates. Effect of guest molecules on mixed hydrate stability and dissociation requires further investigation to understand issues (including characterization, identification and stability) associated with CO₂ capture in CH₄ hydrate reservoir.

In this study, we have performed a core scale (using sandstone) experiments under high pressure and low-temperature conditions using pure CH₄ and CO₂ and CH₄/CO₂ gas mixture with different compositions. During the core scale experiments, the electrical resistance (conductivity) variation during hydrate formation and dissociation was studied to compare the resistance behavior of CO₂ and CH₄ and CH₄-CO₂ mixed hydrate in a consolidated porous medium.

The study shows a difference in resistance variation due to a difference in guest molecules. CO₂ rich hydrates had a lower resistance value compared with CH₄ rich hydrates. This suggests guest molecule effect on the resistance value of gas hydrate-bearing sediments. The difference in resistivity between two gas hydrates can be utilized to monitor CO₂ formation and stability in hydrate-bearing or water-bearing sediments within the hydrate stability zone.