Year: 2021
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide This paper reports the formation and dissociation pattern of hydrate crystals with varying compositions of CH 4 and CO 2 in porous media. Direct visualization was carried out using a high-pressure, water-wet, silicon wafer-based micromodel with a pore network resembling sandstone rock. Hydrate crystals were formed under reservoir conditions ( P = 45–65 bar and T = 1.7–3.5 °C) from either a two-phase system consisting of liquid water and a CH 4 –CO 2 gas mixture or a three-phase system consisting of liquid water, CH 4 -rich gas, and CO 2 -rich liquid. A stepwise pressure reduction method was later applied to visualize multiple dissociation events occurring between the equilibrium pressures of pure CH 4 hydrates and pure CO 2 hydrates. The results showed that liberated gas from the initial dissociation became trapped and immobilized by surrounding undissociated hydrate crystals when the initial hydrate saturation was high. Mixing of liberated gas with liquid water led to rapid reformation of hydrates during the stepwise pressure reduction; the reformed hydrate crystals dissociated at a lower pressure close to the equilibrium pressure of pure CO 2 hydrates. The results demonstrate the possibility of producing gas liberated from local hydrate dissociation while simultaneously reforming hydrates in other parts of the sediments. This is relevant for the proposed production method where CO 2 injection in CH 4 hydrate reservoirs is followed by pressure depletion to enhance the CH 4 gas recovery.
Source: Crystal Growth & Design
Institutions: Technical University of Denmark, University of Bergen
Language: English
Subfield: Environmental Chemistry
Field: Environmental Science
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $5,000
OpenAlex ID: W3146901141