Laboratory Strategies for Hydrate Formation in Fine‐Grained Sediments

Abstract

Fine‐grained sediments limit hydrate nucleation, shift the phase boundary, and hinder gas supply. Laboratory experiments in this study explore different strategies to overcome these challenges, including the use of a more soluble guest molecule rather than methane, grain‐scale gas‐storage within porous diatoms, ice‐to‐hydrate transformation to grow lenses at predefined locations, forced gas injection into water saturated sediments, and long‐term guest molecule transport. Tomographic images and thermal and pressure data provide rich information on hydrate formation and morphology. Results show that hydrate formation is inherently displacive in fine‐grained sediments; lenses are thicker and closer to each other in compressible, high specific surface area sediments subjected to low effective stress. Temperature and pressure trajectories follow a shifted phase boundary that is consistent with capillary effects. Exo‐pore growth results in freshly formed hydrate with a striped and porous structure; this open structure becomes an effective pathway for gas transport to the growing hydrate front. Ice‐to‐hydrate transformation goes through a liquid stage at premelt temperatures; then, capillarity and cryogenic suction compete, and some water becomes imbibed into the sediment faster than hydrate reformation. The geometry of hydrate lenses and the internal hydrate structure continue evolving long after the exothermal response to hydrate formation has completely decayed. Multiple time‐dependent processes occur during hydrate formation, including gas, water and heat transport, sediment compressibility, reaction rate, and the stochastic nucleation process. Hydrate formation strategies conceived for this study highlight the inherent difficulties in emulating hydrate formation in fine‐grained sediments within the relatively short time scale available for laboratory experiments.

Methane Hydrate Film Thickening in Porous Media

“…This work was funded by the Department of Energy, National Energy Technology Laboratory, an agency of the United States Government, through a support contract with Leidos Research Support Team (LRST). Lei & Santamarina, 2018). The specimen diameter in Figure 1b is 33 mm.…”

Xenon Hydrate as an Analog of Methane Hydrate in Geologic Systems Out of Thermodynamic Equilibrium

“…Slow diffusion through interfacial hydrate significantly impacts how gas is transported through the water column or within sediments. The phenomena of hydrate‐crusted gas bubbles in the water column (Warzinski et al, ; Wang et al, ; Waite et al, ) or crustal gas pockets in the sediment (Chen et al, ; Lei & Santamarina, ; Meyer, Flemings, & DiCarlo ; Meyer, Flemings, DiCarlo, et al, ; Sahoo, Marín‐Moreno, et al, ; Sahoo, Madhusudhan, et al, ) have been widely observed and allude to the prolonged coexistence of gas, liquid, and hydrate phases (three‐phase coexistence) that is not predicted by the equilibrium‐phase diagram (Fu et al, ). Although the three‐phase configuration across the interface is out of equilibrium, the two boundaries of the growing hydrate layer can independently approach local equilibria with the phase it contacts (gas or liquid).…”

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

“…Difficulties forming hydrate from dissolved phase methane in porous media on reasonable timescales are particularly pronounced for fine‐grained sediments owing to high capillary pressures (Clennell et al, ), low permeability, and electrical charges that interfere with hydrate nucleation (Lei & Santamarina, ). Waite and Spangenberg () proposed changes in the process for supersaturating water with methane prior to its being circulated through the porous media pack.…”

“…Fine-grained particles that are mixed with coarser sediments can be mobilized under certain conditions and are also considered a component of pore fill in some cases. (2018) On the importance of advective versus diffusive transport in controlling the distribution of methane hydrate in heterogeneous marine sediments Lei and Santamarina (2018) Laboratory strategies for hydrate formation in fine-grained sediments (also fines) You and Flemings (2018) Methane hydrate formation in thick sandstones by free gas flow Effect of gas flow rate on hydrate formation within the hydrate stability zone Meyer, Flemings, DiCarlo, You, et al (2018) Experimental investigation of gas flow and hydrate formation within the hydrate stability zone Sahoo et al (2018) Presence and consequences of coexisting methane gas with hydrate under two phase water-hydrate stability conditions Almenningen et al (2018) Upscaled anisotropic methane hydrate critical state model for turbidite hydrate-bearing sediments at East Nankai Trough Ge et al (2018) Laboratory investigation into the formation and dissociation process of gas hydrate by low-field nuclear magnetic resonance technique Role of fines Han et al (2018) Depressurization-induced fines migration in sediments containing methane hydrate: X-Ray computed tomography imaging experiments Hyodo et al (2017) Influence of fines content on the mechanical behavior of methane hydrate-bearing sediments Jang et al (2018) Impact of pore fluid chemistry on fine-grained sediment fabric and compressibility Taleb et al (2018) Hydromechanical properties of gas hydrate-bearing fine sediments from in situ testing Geomechanical and hydraulic properties Spangenberg et al (2018) A quick look method to assess the dependencies of rock physical sediment properties on the saturation with pore-filling hydrate Madhusudhan et al (2019) The effects of hydrate on the strength and stiffness of some sands Kossel et al (2018) The dependence of water permeability in quartz sand on gas hydrate saturation in the pore space Gil et al (2019) Numerical analysis of dissociation behavior at critical gas hydrate saturation using depressurization method Cook and Waite (2018) Archie's saturation exponent for natural gas hydrate in coarse-grained reservoirs Zhou et al (2018) Upscaled anisotropic methane hydrate critical state model for turbidite hydrate-bearing sediments at East Nankai Trough Coupled numerical modeling Sánchez et al (2018) Coupled numerical modeling of gas hydrate-bearing sediments: From laboratory to field-scale analyses Kim et al (2018) Methane production from marine gas hydrate deposits in Korea: Thermal-hydraulic-mechanical simulation on production wellbore stabilit...…”