Pore-level hydrate formation mechanisms using realistic rock structures in high-pressure silicon micromodels

Abstract

We report pore-level visualization of CO2 and CH4 gas hydrate formation with dynamic growth patterns within a 2D porous silicon wafer micromodel with realistic pore shapes and sizes. Direct observation of pore-scale hydrate growth patterns at reservoir conditions provides an improved framework for fundamental studies of sediment-hosted gas hydrates. The growth pattern and formation rate are discussed with respect to wetting films, fluid distribution, and PT conditions for CH4 and CO2 hydrate. Hydrates appeared initially on the interface between gas spheres and thin water films coating the grain surface, followed by a continuous hydrate growth throughout the pore space. Redistribution of hydrate was observed over several hours at stable conditions. Furthermore, repeated hydrate formation occurred more rapidly and at higher temperatures than during primary formation. The understanding of pore-scale growth of sedimentary gas hydrate has great value in describing hydrates in a geological setting and toward production of a vast energy resource. It may also be a key feature in CO2 storage schemes.