Gas Permeability of Sandy Sediments: Effects of Phase Changes in Pore Ice and Gas Hydrates

Abstract

The gas permeability of sandy porous sediments is studied in freezing/thawing and pore gas hydrate formation/dissociation experiments using a specially designed system. The permeability of sandy soil to gas is controlled by phase changes of the pore water components (water, ice, or gas hydrate) depending on temperature and pressure. The gas permeability of the sand samples decreases upon freezing and during the formation of pore gas hydrates but increases when pore gas hydrates dissociate upon pressure drop to below-equilibrium values. The magnitude of permeability decrease and increase varies as a function of the initial water–ice saturation and the pore space structure. Clay contents and mineralogy affect the behavior of gas permeability in frozen and thawed sand samples containing a clay component. The experimental results can have multiple uses: modeling and testing of economically feasible techniques for gas production from permafrost Arctic reservoirs, including hydrate-bearing sediments, or mapping of permeable zones for tracing methane emission in high latitudes.

Prospect and Challenges of Hydrate-Based Hydrogen Storage in the Low-Carbon Future

“…In addition to gas storage, − gas hydrates are relevant to other sectors of the environmental and energy industry such as a cleaner energy source, ,− gas separation and carbon capture, ,− carbon sequestration, − desalination of saline water, − and cold energy storage . Gas hydrates also present a long-standing hazard to the flow assurance in oil and gas industry as they tend to cause flow blockage. − Owing to such scientific and application significances, research in gas hydrates has grown strongly over recent decades.…”

Experimental Study On the Effect of Hydrate Filling On the Mechanical Properties of Marine Sediments in the Shenhu Area, South China Sea

“…With the increasing demand for energy, unconventional oil and gas are gradually becoming the focus of exploration and development, and natural gas hydrate is one such target. Natural gas hydrate is a cage-shaped crystalline compound formed by methane molecules (the main component) and water molecules under low-temperature and high-pressure conditions. − Due to the properties of wide distribution, abundant reserves, high energy density, and lack of subsequent pollution, − many countries, such as the United States, Canada, and China, have developed long-term research programs on natural gas hydrates. − However, hydrate is mainly present in shallow strata in deep water and permafrost because of the low temperature and high pore pressure generation conditions. − Due to the shallow depth, these formations are characterized by weak cementation, low permeability, and easy deformation. During drilling and production, hydrate formations are at great risk of borehole instability, sand production, and formation subsidence .…”

Understanding Hysteresis and Gas Trapping in Dissociating Hydrate-Bearing Sediments Using Pore Network Modeling and Three-Dimensional Imaging

“…Accordingly, different methods have been proposed to extract methane from these low-carbon energy reservoirs. The process of extracting natural gas from hydrate-bearing sediments (HBS) is described as a multiphase flow associated with chemical reactions within a porous medium, involving heat transfer, water and gas flow, , fine-particle migration, and hydrate phase transition. , To characterize multiphase flow properties in HBS, permeability measurement is needed, which is critical to understanding water and gas production , and methane releases from hydrates into the atmosphere and ocean …”

“…The process of extracting natural gas from hydrate-bearing sediments (HBS) is described as a multiphase flow associated with chemical reactions within a porous medium, involving heat transfer, 5 water and gas flow, 6,7 fineparticle migration, 8 and hydrate phase transition. 9,10 To characterize multiphase flow properties in HBS, permeability measurement is needed, which is critical to understanding water and gas production 11,12 and methane releases from hydrates into the atmosphere and ocean. 13 Hydrates occupy the pore space in HBS and influence the effective permeability, k eff (i.e., single-phase permeability), which is defined as the intrinsic (or absolute) permeability, k int , that reflects the intrinsic ability of sediments without hydrates to allow single-phase flow and does not depend on the fluid type.…”