In Situ Raman Spectroscopy Investigation of the Dissociation of Methane Hydrate at Temperatures Just below the Ice Point

Komai, Takeshi; Kang, Seong-Pil; Yoon, Ji-Ho; Yamamoto, Yoshitaka; Kawamura, Taro; Ohtake, Mitsuru

doi:10.1021/jp0310955

Cited by 61 publications

(47 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…When hydrate dissociates at temperatures below the freezing point of ice (<273.2 K) yet outside the hydrate region of stability, unexpectedly slow rate of hydrate dissociation is observed, which is a phenomenon termed as ''self-preservation'' or ''anomalous preservation'' in the literature [85][86][87]. The most popular explanation for the phenomenon is that the endothermic heat of dissociation causes the dissociated water to form ice, preventing further dissociation within the hydrate region.…”

Section: Self-preservation Phenomenamentioning

confidence: 99%

Review of natural gas hydrates as an energy resource: Prospects and challenges

et al. 2016

View full text Add to dashboard Cite

Section: Self-preservation Phenomenamentioning

confidence: 99%

Review of natural gas hydrates as an energy resource: Prospects and challenges

et al. 2016

View full text Add to dashboard Cite

“…Methane gas release from hydrate decomposition was also observed with high-resolution optical microscopy, which offered some information on 2-D gas/water rearrangements during hydrate decomposition [Katsuki et al, 2008]. In-situ Raman spectroscopy was found helpful in observing the decomposition of hydrates by providing time-resolved spectra for CH 4 molecules encaged in hydrate cavities during hydrate decomposition [Komai et al, 2004;Liu et al, 2008], but powerless in illustrating Geochemistry, Geophysics, Geosystems 10.1002/2016GC006521 detailed morphological characteristics of decomposing hydrates in pores. Cryo scanning electron microscopy (cryo-SEM) allows a more detailed access of surface properties down to the nanometer scale on recovered samples, which has been extremely useful for the observation of GHs and ice surfaces [Falenty et al, 2014;Kuhs et al, 2000].…”

Section: Introductionmentioning

confidence: 99%

Synchrotron X-ray computed microtomography study on gas hydrate decomposition in a sedimentary matrix

Yang

Falenty

Chaouachi

et al. 2016

Geochem. Geophys. Geosyst.

198

109

View full text Add to dashboard Cite

In-situ synchrotron X-ray computed microtomography with sub-micrometer voxel size was used to study the decomposition of gas hydrates in a sedimentary matrix. Xenon-hydrate was used instead of methane hydrate to enhance the absorption contrast. The microstructural features of the decomposition process were elucidated indicating that the decomposition starts at the hydrate-gas interface; it does not proceed at the contacts with quartz grains. Melt water accumulates at retreating hydrate surface. The decomposition is not homogeneous and the decomposition rates depend on the distance of the hydrate surface to the gas phase indicating a diffusion-limitation of the gas transport through the water phase. Gas is found to be metastably enriched in the water phase with a concentration decreasing away from the hydrate-water interface. The initial decomposition process facilitates redistribution of fluid phases in the pore space and local reformation of gas hydrates. The observations allow also rationalizing earlier conjectures from experiments with low spatial resolutions and suggest that the hydrate-sediment assemblies remain intact until the hydrate spacers between sediment grains finally collapse; possible effects on mechanical stability and permeability are discussed. The resulting time resolved characteristics of gas hydrate decomposition and the influence of melt water on the reaction rate are of importance for a suggested gas recovery from marine sediments by depressurization.

show abstract

“…Komai et al 37 performed a series of experiments to analyze the kinetics of MH dissociation via in situ Raman spectroscopy. Several methods have recently been used to monitor methane hydrate (MH) dissociation directly, such as magnetic resonance imaging (MRI), Raman spectroscopy, scanning electron microscopy (SEM), and X-ray computed tomography (CT).…”

Section: Introductionmentioning

confidence: 99%

Assessment of gas production from natural gas hydrate using depressurization, thermal stimulation and combined methods

Song

Zhang

et al. 2016

RSC Adv.

View full text Add to dashboard Cite

The largest sources of hydrocarbons worldwide are distributed in the permafrost and submarine sediments in the form of methane hydrates, but exploitation of these hydrocarbons is still years away from being economical, safe, and commercially viable; thus, further research is needed. To analyze the characteristics of methane hydrate (MH) dissociation and evaluate the gas production during the application of different MH decomposition methods, this study firstly compared MH dissociation during depressurization, thermal stimulation, and combined method (depressurization + thermal stimulation) treatments using magnetic resonance imaging (MRI) in situ observation. In particular, the influences of back-pressure and temperature on hydrate dissociation, the hydrate saturation, the rate of hydrate dissociation and MRI images from each of the three methods were investigated. The results proved that during application of the depressurization and combined methods at different back-pressures (2.2-2.6 MPa), the MH dissociation proceeded via radial dissociation rather than axial dissociation; moreover, during the application of the thermal stimulation method at different dissociation temperatures (278.15-288.15 K), the MH dissociated uniformly. Overall, a combination of depressurization and thermal stimulation at the initial stage of hydrate decomposition was proposed and comparison of the three methods demonstrated that the combined method had obvious advantages for methane treatment.Specifically, the combined method was capable of solving the problems related to low gas production and poor energy efficiency that were encountered when using either the depressurization or thermal stimulation method alone.

show abstract

In Situ Raman Spectroscopy Investigation of the Dissociation of Methane Hydrate at Temperatures Just below the Ice Point

Cited by 61 publications

References 30 publications

Review of natural gas hydrates as an energy resource: Prospects and challenges

Review of natural gas hydrates as an energy resource: Prospects and challenges

Synchrotron X-ray computed microtomography study on gas hydrate decomposition in a sedimentary matrix

Assessment of gas production from natural gas hydrate using depressurization, thermal stimulation and combined methods

Contact Info

Product

Resources

About