In Situ Observations of Methane Hydrate Formation Mechanisms by Raman Spectroscopy

2006 ◽  
Vol 912 (1) ◽  
pp. 593-601 ◽  
Author(s):  
T. UCHIDA ◽  
R. OKABE ◽  
S. MAE ◽  
T. EBINUMA ◽  
H. NARITA
Keyword(s):  
Raman Spectroscopy ◽  
Methane Hydrate ◽  
Hydrate Formation ◽  
Formation Mechanisms ◽  
In Situ Observations

Measurements of physical properties of gas hydrates and in situ observations of formation and decomposition processes via Raman spectroscopy and X-ray diffraction

2003 ◽  
Vol 81 (1-2) ◽  
pp. 351-357 ◽  
Author(s):  
T Uchida ◽  
S Takeya ◽  
L D Wilson ◽  
C A Tulk ◽  
J A Ripmeester ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Physical Properties ◽  
Gas Hydrates ◽  
Hydrate Formation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrate Layer ◽  
Decomposition Processes ◽  
In Situ Observations

Gas hydrate properties and phase transition kinetics were studied using Raman spectroscopic and X-ray diffraction methods. These techniques have the advantage of measuring physical properties such as crystal structure, gas composition, and cage occupancy of gas molecules without decomposing the sample. In situ observations using these techniques are indicative of formation and decomposition processes in gas hydrates. Raman spectroscopy is used for the analysis of gas concentrations and gas compositions of gas hydrates. The ν1 symmetrical C–H stretching vibration mode of methane molecules in the hydrate phase shows a doublet, and the relative intensity of the peaks determines the cage-occupancy ratio. However, as the Raman method is not standard for this application, we evaluated the method by analyzing the same methane hydrate sample using NMR and Raman scattering in a laboratory in Canada and also comparing the data with the Raman measurements made on the same sample in a laboratory in Japan. The data were consistent with all three measurements. In addition, in situ measurements of hydrate formation and decomposition were done by X-ray diffraction. The transformation of ice into CO2 hydrates occurred in two steps: at first a CO2 hydrate layer rapidly formed a coating on the ice surface and then the CO2 hydrate slowly grew according to the diffusion rates of CO2 and H2O molecules through the hydrate layer to the reaction sites. The same methods were used to observe the self-preservation effect of methane hydrates. PACS Nos.: 82.80Ch, 61.10Nz

Insights into the Kinetics of Methane Hydrate Formation in a Stirred Tank Reactor by In Situ Raman Spectroscopy

2015 ◽  
Vol 3 (9) ◽  
pp. 925-934 ◽  
Author(s):  
Jong Min Lee ◽  
Seong Jun Cho ◽  
Ju Dong Lee ◽  
Praveen Linga ◽  
Kyung Chan Kang ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Methane Hydrate ◽  
Hydrate Formation ◽  
Stirred Tank ◽  
In Situ Raman Spectroscopy ◽  
Stirred Tank Reactor ◽  
Tank Reactor ◽  
In Situ Raman ◽  
Kinetics Of

In Situ Observations of High-Pressure Phase Transformations in a Synthetic Methane Hydrate

2002 ◽  
Vol 106 (1) ◽  
pp. 30-33 ◽  
Author(s):  
Hiroyasu Shimizu ◽  
Tatsuya Kumazaki ◽  
Tetsuji Kume ◽  
Shigeo Sasaki
Keyword(s):  
High Pressure ◽  
Phase Transformations ◽  
Methane Hydrate ◽  
High Pressure Phase ◽  
In Situ Observations ◽  
Pressure Phase

scholarly journals Homogenization Experiments of Crystal-Rich Inclusions in Spodumene from Jiajika Lithium Deposit, China, under Elevated External Pressures in a Hydrothermal Diamond-Anvil Cell

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Jiankang Li ◽  
I-Ming Chou
Keyword(s):  
Diamond Anvil Cell ◽  
Aqueous Fluid ◽  
Formation Mechanisms ◽  
External Pressures ◽  
Sample Chamber ◽  
New Type ◽  
Diamond Anvil ◽  
In Situ Observations ◽  
Total Dissolution

Extensive studies of the crystal-rich inclusions (CIs) hosted in minerals in pegmatite have resulted in substantially different models for the formation mechanism of the pegmatite. In order to evaluate these previously proposed formation mechanisms, the total homogenization processes of CIs hosted in spodumene from the Jiajika pegmatite deposit in Sichuan, China, were observed in situ under external H2O pressures in a new type of hydrothermal diamond-anvil cell (HDAC). The CIs in a spodumene chip were loaded in the sample chamber of HDAC with water, such that the CIs were under preset external H2O pressures during heating to avoid possible decrepitation. Our in situ observations showed that the crystals within the CIs were dissolved in carbonic-rich aqueous fluid during heating and that cristobalite was usually the first mineral being dissolved, followed by zabuyelite and silicate minerals until their total dissolution at temperatures between 500 and 720°C. These observations indicated that the minerals within the CIs were daughter minerals crystallized from an entrapped carbonate- and silica-rich aqueous solution and therefore provided useful information for evaluating the formation models of granitic pegmatites.

Effects of Cyclodextrin Solutions on Methane Hydrate Formation

2007 ◽  
Author(s):  
Ryo Nozawa ◽  
Mohammad Ferdows ◽  
Kazuhiko Murakami ◽  
Masahiro Ota
Keyword(s):  
Raman Spectroscopy ◽  
Induction Time ◽  
Methane Hydrate ◽  
Methane Concentration ◽  
Formation Rate ◽  
Hydrate Formation ◽  
Formation Water ◽  
Advanced Method

In this paper, we suggest the advanced method of methane hydrate formation by cyclodextrin solutions. The structures of the methane hydrate were experimentally investigated by Raman spectroscopy. The induction time of the methane hydrate formation becomes by shorter 10–30 times and formation rate become by faster 2–4 times originated in the increased methane concentration of hydrate formation water by adding cyclodextrins. The results by the Raman spectroscopy indicate that the structure I methane hydrate is produced and methane molecules exist in both Large and Small cages.

Methane-Hydrate-Formation Processes in Methane/Water Bubbly Flows

SPE Journal ◽  
2016 ◽  
Vol 22 (03) ◽  
pp. 746-755 ◽  
Author(s):  
T.. Shimizu ◽  
Y.. Yamamoto ◽  
N.. Tenma
Keyword(s):  
Methane Hydrate ◽  
Hydrate Formation ◽  
Production Method ◽  
Gas Production ◽  
Bubbly Flows ◽  
Turbulent Shear ◽  
Formation Processes ◽  
Flow Loop ◽  
Offshore Production

Summary Offshore natural-gas production from methane-hydrate (MH) reservoirs has received considerable attention. In this study, the offshore production method is briefly described, followed by the flow loop experiments performed to investigate the formation processes of MH in methane-in-water bubbly flows. Transient processes of phase transformation are characterized by phase paths, flow morphologies, pump heads, and in-situ particle-size measurements. It is realized that an MH slurry is generated by MH shells covering unconverted bubbles, whereas it can be transformed into a colloidal flow with fine crystalline particles under an intense turbulent shear. This study suggests that, in practice, the flow pattern under MH formation would be determined by the phase path and the flow velocity in the pipeline, which is one of the important factors considered in the evaluation of flow-assurance risks.

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