Permeability of Laboratory-Formed Methane-Hydrate-Bearing Sand: Measurements and Observations Using X-Ray Computed Tomography

Abstract

Methane hydrate was formed in two moist sands and a sand-silt mixture under a confining stress in an x-ray transparent pressure vessel. Three initial water saturations were used to form three different methane hydrate saturations in each medium. X-ray computed tomography (CT) was used to observe locationspecific density changes caused by hydrate formation and flowing water. Gas permeability measurements in each test for the dry, moist, frozen, and hydrate-bearing states are presented. As expected, the effective permeabilities (intrinsic permeability of the medium multiplied by the relative permeability) of the moist sands decreased with increasing moisture content. In a series of tests on a single sample, the effective permeability typically decreased as the pore space became more filled, in the order of dry, moist, frozen, and hydrate-bearing. In each test, water was flowed through the hydrate-bearing medium, and we observed the location specific changes in water saturation using CT scanning. We compared our data to a number of models, and our relative permeability data compare most favorably with models in which hydrate occupies the pore bodies rather than the pore throats. Inverse modeling (using the data collected from the tests) will be performed to extend the relative permeability measurements.

Permeability of sediment cores from methane hydrate deposit in the Eastern Nankai Trough

“…To date, experimental studies have evaluated the effective permeability of hydrate-bearing sediments using cores with synthetic methane hydrate (Kleinberg et al, 2003;Kneafsey et al, 2011b;Liang et al, 2011;Seol and Kneafsey, 2011;Konno et al, 2013) and CO 2 hydrate (Kumar et al, 2010). In order to characterize methane hydrate-bearing sediment, proton nuclear magnetic resonance (NMR) is applied to measure pore size distribution of unconsolidated sediment (e.g., Minagawa et al, 2008).…”

Prediction Performance of Permeability Models in Gas-Hydrate-Bearing Sands

“…Growth habits of hydrate within pore spaces greatly influence the resulting permeability of GHBS (Nimblett and Ruppel 2003). Understanding how growth habit affects the gas and water relative permeability is important for accurate gas-production estimates and economic viability (Moridis et al 2011, Kneafsey et al 2011. Several investigations have been carried out on hydrateformation habits of laboratory synthesized samples (Moridis et al 2011); formation habit is influenced by several factors including sediment mineralogy, texture, water salinity, gas composition, whether hydrate forms from free or dissolved gas, and pore-space microgeometry (Kleinberg et al 2003).…”

“…Hence, permeability measurements in the presence of GHs have been carried out using laboratory synthesized samples (Jaiswal 2004;Kumar et al 2010;Kneafsey et al 2011;Liang et al 2011). In laboratory synthesized samples, hydrate growth habit is strongly governed by the underlying preparation method.…”

Advances in Study of Mechanical Properties of Gas Hydrate-Bearing Sediments

“…More investigated work is required to clarify how gas hydrate occupies the pore space in natural porous media and in laboratory samples and how this affects transport parameters. For this target, some imaging techniques such as X-ray computed tomography (CT), nuclear magnetic resonance (NMR) should be used in measurements [59,77].…”