Introduction to Special Issue on Gas Hydrate in Porous Media: Linking Laboratory and Field‐Scale Phenomena

Abstract

The proliferation of drilling expeditions focused on characterizing natural gas hydrate as a potential energy resource has spawned widespread interest in gas hydrate reservoir properties and associated porous media phenomena. Between 2017 and 2019, a Special Section of this journal compiled contributed papers elucidating interactions between gas hydrate and sediment based on laboratory, numerical modeling, and field studies. Motivated mostly by field observations in the northern Gulf of Mexico and offshore Japan, several papers focus on the mechanisms for gas hydrate formation and accumulation, particularly with vapor phase gas, not dissolved gas, as the precursor to hydrate. These studies rely on numerical modeling or laboratory experiments using sediment packs or benchtop micromodels. A second focus of the Special Section is the role of fines in inhibiting production of gas from methane hydrate, controlling the distribution of hydrate at a pore scale, and influencing the bulk behavior of seafloor sediments. Other papers fill knowledge gaps related to the physical properties of hydrate‐bearing sediments and advance new approaches in coupled thermal‐mechanical modeling of these sediments during hydrate dissociation. Finally, one study addresses the long‐standing question about the fate of methane hydrate at the molecular level when CO2 is injected into natural reservoirs under hydrate‐forming conditions.

Timescales and Processes of Methane Hydrate Formation and Breakdown, With Application to Geologic Systems

“…The absence of water that can be used for additional gas hydrate formation may then make it possible to pass gas through migration pathways within the hydrate stability zone without forming additional gas hydrate (Liu & Flemings, 2006; Smith et al, 2014). After many years in which the natural hydrates community focused primarily on formation of hydrate from aqueous phase gas in porous media (see discussion in Ruppel et al, 2019), more research is now being undertaken on hydrate formation from vapor phase. On the other hand, some researchers (e.g., VanderBeek & Rempel, 2018) have challenged the need to routinely invoke hydrate formation from vapor phase gas within the stability zone to explain high‐saturation hydrate‐bearing deposits.…”