Thermal properties of methane hydrate‐bearing sediments and surrounding mud recovered from Nankai Trough wells

Abstract

This paper presents the measurement of the thermal constants of natural methane hydrate-bearing sediments and mud layer samples recovered from wells. Core samples were recovered from the Tokai-oki test wells (Nankai Trough, Japan) in 2004. The thermal conductivity, thermal diffusivity, and specific heat of the samples were simultaneously determined using the hot-disk transient method. The thermal conductivity of natural hydrate-bearing sediments decreased slightly with increasing porosity. In addition, the thermal diffusivity of hydrate-bearing sediments decreased as the porosity increased. Moreover, we also used simple models to calculate the thermal conductivity and diffusivity. Estimations of the distribution model (geometric mean model) were relatively consistent with the measured results, suggesting that sand grains and hydrates should be independently distributed for hydrate-bearing sediments, which exhibit a pore-filling pattern. The measurement results were also consistent with the thermal diffusivity, which was estimated by dividing the thermal conductivity obtained from the distribution model by the specific heat taken from the arithmetic mean. Finally, our estimate of the thermal conductivity of silt soil was much lower than that for sand soil in hydrate-bearing sediment, which suggests that the small grains influence thermal conductivity.

Bulk sediment mineralogy of gas hydrate reservoir at the East Nankai offshore production test site

“…Goto and Matsubayashi (2009) suggested that each rock-forming mineral has its own thermal characteristics and the thermal properties of bulk sediments can be estimated by using mineral contents and porosity. However, the semi-quantitative evaluation in this study did not include the amount of unidentified minerals, glassy matrix, and humic substances, and thus it is further required to quantitatively measure these contents, together with the direct measurement of sediment thermal properties for data calibration (e.g., Muraoka et al, 2014).…”

Thermal Properties of a Supercooled Synthetic Sand–Water–Gas–Methane Hydrate Sample

“…Muraoka et al 16 measured natural hydrate-bearing sediment cores recovered from Nankai Trough wells. They tested simple thermophysical models and concluded that the distribution model (geometric mean model) is suitable for estimating the thermal conductivity of hydrate-bearing sediments comprising sand, water, and MH.…”

Conditions for the Long‐Term Preservation of a Deep Brine Reservoir in Ceres

“…Freezing occurs top down and results in the development of a crust that is ice rich. Silicates are a minor component of the mixture, and thus their impact on the thermal conductivity is small; see the supporting information, for example,Dai et al (2015),Durham et al (2010),Grimm and Mcween Jr (1989),Grindrod et al (2008),Muraoka et al (2014),Opeil et al (2010),Schofield et al (2014), Clathrates may represent the dominant form of water at pressures of a few MPa.…”