This study was financially supported by the MH21 Research Consortium for Methane Hydrate Resources in Japan and the National Methane Hydrate Exploitation Program by the Ministry of Economy, Trade, and Industry. The authors would like to thank T. Maekawa and S. Goto for their assistance with the experiments.
Reprinted figures with permission from (Muraoka, M., Susuki, N., Yamaguchi, H., Tsuji, T., Yamamoto, Y., Energy Fuels, 29(3), 2015, 1345-1351., 2015, DOI: 10.1021/ef502350n). Copyright (2015) American Chemical Society.

Note: Please consult all relevant material safety data sheets as this study uses high-pressure flammable methane gas and a large high-pressure vessel. Wear a helmet, safety glasses, and safety boots. If the temperature control system stops, the pressure in the vessel increases with MH dissociation. To prevent accidents, the use of a safety valve system is strongly recommended to automatically release the methane gas to the atmosphere. The safety valve system can work without electrical power supply.
1. Preparation of the Sand-water-methane Gas Samples9
<ol>
	<li>Place the high-pressure vessel on the vibrating table.</li>
	<li>Pour 1.5 L of pure water in a water bottle and 4,000 g silica sand in a sand bottle. Accurately weigh the masses of sand and water in the sand and water bottles, respectively.</li>
	<li>Pour 1 L of pure water in the high-pressure vessel with an inner volume of 2,110 cm3 from a water bottle until the water fills half the inner vessel.</li>
	<li>Turn on the vibrating table to vibrate the entire vessel. Set the vibration rate and the power supply to 50 Hz and 220 W, respectively. Apply the vibration until the completion of step 1.5. Remove the residual air in the drain line and sintered metallic filter at the bottom of the vessel by vibrating the vessel.</li>
	<li>Pour 3,300 g silica sand from a sand bottle into the vessel at a constant rate of approximately 1 g sec&#8722;1 using a funnel held near the water surface while the entire vessel is vibrated to ensure uniform packing.</li>
	<li>Stop the vibration when the water reaches the rim of the vessel.</li>
	<li>Place a ring as a temporary wall on the rim of the vessel to prevent water from spilling.</li>
	<li>Vibrate the vessel again at 50 Hz and 220 W.</li>
	<li>When the sand reaches the rim of the vessel (height 140 mm), turn off the vibration.</li>
	<li>Remove the temporary wall and excess pore water using the drain line. Pour the excess pore water back into the water bottle.</li>
	<li>Pack the sand by vibrating the vessel once or twice at 50 Hz and 300 W for 1 sec and add more sand if necessary.</li>
	<li>Weigh the masses of sand and water in the sand and water bottles. Calculate the sand and water masses in the vessel from the mass differences in the sand and water bottles. In this experiment, the masses of sand and water in the vessel were 3,385 g and 823.6 g, respectively. The mass of water in the vessel is denoted as wtotal.</li>
	<li>Cover the high-pressure vessel with a stainless steel lid and tighten the bolts of diagonally opposite pairs in sequence.</li>
	<li>Move the high-pressure vessel from the vibrating table to the table intended for the experiment.</li>
	<li>Cover the high-pressure vessel with the heat insulator for controlling the temperature.</li>
	<li>Connect the high-pressure pipelines and the cooling water flow lines to the high-pressure vessel.</li>
	<li>Open the valves of the input and output gas pipelines. Ventilate 10 L methane at a rate of 800 ml min&#8722;1 until no excess water discharges into the trap under atmospheric pressure. The sand discharge is prevented by a sintered metallic filter fixed on the bottom of the vessel. The residual water remains on the sand surface because the hydrophilic silica sand adsorbs the water molecules.</li>
	<li>Weigh the mass of water in the trap, wtrap, to determine the gas volume in the vessel. Determine the mass of residual water, wres, in the vessel using the equation wres = wtotal &#8722; wtrap. In this case, wres and wtrap was 360.6 g and 463.0 g, respectively.</li>
	<li>Determine the sample porosity using the formula &#1136; = 1 - Vsand / Vcell, where Vsand is the volume of the sand determined by the ratio of sand mass to sand density (i.e., &#961;s = 2,630 kg m&#8722;3), and Vcell is the inner volume of the vessel. The porosity&#160;&#1136; of the sample was 0.39.</li>
	<li>Close the valve of the output gas line. Inject methane to increase the pore pressure of methane in the vessel to approximately 12.1 MPa at room temperature (i.e., 31.6 &#176;C).</li>
	<li>Close the valve of the input gas line.</li>
	<li>Start recording the pressure and temperature in the vessel during the experiment using the data logger. The data sampling interval is 5 sec. The total experimental time is approximately 3,000 min.</li>
</ol>
2. MH Synthesis and Thermal Properties&#39; Measurement of the Supercooled Sample9
<ol>
	<li>Turn on the chiller for cooling the vessel from room temperature to 2.0 &#176;C by circulating the coolant. Let the coolant circulate from the chiller to the bottom of the vessel, from there to the lid of the vessel, and finally back to the chiller. The temperature change rate in the vessel was approximately 0.001 &#176;C sec&#8722;1.</li>
	<li>Set the measurement parameters using the TPS analyzer software. Set the sensor type to sensor design #7577. Set the output power W0 to 30 mW and the measuring time to 5 sec. Note that the appropriate parameters should be changed if the sensor type or sample conditions change. Set the parameters to increase the temperature from 1 &#176;C to 1.5 &#176;C.</li>
	<li>Calculate the degree of supercooling, &#916;Tsup, with the following equation: 
	&#916;Tsup = Teq(P) &#8722; T. (3) 
	Teq(P) is the equilibrium temperature of MH as a function of pressure P. Teq(P) is calculated using the CSMGem software1.&#160; P and T are the pressure and temperature in the vessel measured by using pressure and temperature gauges, respectively.</li>
	<li>Simultaneously measure the thermal conductivity, thermal diffusivity, and volumetric specific heat using the TPS analyzer after &#916;Tsup is greater than 2 &#176;C.</li>
	<li>Switch the TPS probe connected to the thermal properties analyzer after each measurement. Switch the cables between the TPS probes and the analyzer manually during the experiment9. The connection diagram is shown in Figure S2 in reference9. The switching sequence for each sensor is no. 6 &#8594; 2 &#8594; 7 &#8594; 5 &#8594; 1 &#8594; 9 &#8594; 4 &#8594; 3 &#8594; 8 &#8594; 6&#8230;. The sequence is based on the distance between the sensors, which is set as far as possible to prevent the residual heat from affecting the measurements. Collect data every 3-5 min.</li>
	<li>Repeat the measurements until &#916;Tsup reaches 2 &#176;C again. In this experiment, &#916;Tsup initially increases with time. After &#916;Tsup reaches the maximum value, &#916;Tsup gradually decreases to 0 &#176;C because the pressure decreases with the formation of MH. Check if &#916;Tsup is greater than 2 &#176;C prior to the TPS measurements using equation 3.</li>
	<li>Ensure that the temperature profile is not affected by MH melting. If MH melts during the measurements, the temperature will not increase because melting of MH is an endothermic reaction. Check the temperature profile during the measurements, and is discussed in the results section.</li>
	<li>Perform the thermal properties&#39; analysis for all temperature profile data using the TPS technique.</li>
</ol>
3. Calculation of the Saturation Change of the Sample9,11
Note: The degree of saturation for MH, water, and gas in the sample as a function of time t is calculated using the equation of state of the gas. The calculation details and equations used are previously described11.
<ol>
	<li>Calculate the methane gas volume Vgas,t at time t 
	<img alt="Equation 4" src="/files/ftp_upload/53956/53956eq4.jpg" /> 
	where Q is the initial volume of gas in the vessel, VMH,t &#8722; 1 is the volume of MH at time t &#8722; 1, and RVhw is the volume ratio of water and MH. 
	<img alt="Equation 5" src="/files/ftp_upload/53956/53956eq5.jpg" /> 
	In Equation 5, n is the hydration number of MH (~6), &#961;MH and &#961;water correspond to the density of MH and water, respectively, and wMH and wwater denote the molecular mass of MH and water, respectively.</li>
	<li>Calculate the amount &#916;Mt (mol) of MH formed from t &#8722; 1 to t 
	<img alt="Equation 6" src="/files/ftp_upload/53956/53956eq6.jpg" /> 
	where R is the gas constant, P is the pressure of the methane gas, and Zt (Tgas,t, Pgas,t) is the compression coefficient of methane at time t. We9 and Sakamoto et al.11 have used the Benedict&#8211;Webb&#8211;Rubin (BWR) equation, as modified by Lee and Kesler, for calculating Zt12,13. For this calculation, the formulas (3&#8211;7.1)&#8211;(3&#8211;7.4) of the BWR equation13 and the Lee&#8211;Kesler constants are used in Tables 3&#8211;7 of reference13.</li>
	<li>Calculate the volume change &#916;VMH,t of MH from t &#8722; 1 to t 
	<img alt="Equation 7" src="/files/ftp_upload/53956/53956eq7.jpg" /> 
	where Ps is the reference pressure of 101325 Pa, Ts is the reference temperature of 273.15 K, Zs is the compression coefficient at Ps and Ts (Zs ~1), and VCH4 is the ratio of the methane gas volume in the unit volume of MH [Nm3 m&#8722;3]. Use a VCH4 value of 165.99 [Nm3 m&#8722;3].</li>
	<li>Calculate the volume VMH,t of MH at time t 
	<img alt="Equation 8" src="/files/ftp_upload/53956/53956eq8.jpg" /></li>
	<li>Calculate the volume of water Vwater,t in the pressure vessel at time t 
	<img alt="Equation 9" src="/files/ftp_upload/53956/53956eq9.jpg" /> 
	where Vwater,1 is the initial volume of water.</li>
	<li>Repeat the calculations using Equations. 4&#8211;9 at time t = 2, 3, &#8230; to determine the change in the saturation of water, methane, and MH11. The initial condition is t = 1, i.e., Vgas,1 = Q. The P and T at time t are taken from the data logs9. The calculation results are shown in the following section.</li>
</ol>

<ol>
	<li>Sloan, E. D., Koh, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Clathrate Hydrates of Natural Gases, 3rd ed. , (2007).</li><li>Hatzikiriakos, S. G., Englezos, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+relationship+between+global+warming+and+methane+gas+hydrates+in+the+earth.">The relationship between global warming and methane gas hydrates in the earth.</a> Chem. Eng. Sci. 48 (23), 3963-3969 (1993).</li><li>Yamamoto, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Overview+and+introduction:+pressure+core-sampling+and+analyses+in+the+2012-2013+MH21+offshore+test+of+gas+production+from+methane+hydrates+in+the+eastern+Nankai+Trough.">Overview and introduction: pressure core-sampling and analyses in the 2012-2013 MH21 offshore test of gas production from methane hydrates in the eastern Nankai Trough.</a> Mar. Petrol. Geol. 66 (Pt 2), 296 (2015).</li><li>Fujii, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Geological+setting+and+characterization+of+a+methane+hydrate+reservoir+distributed+at+the+first+offshore+production+test+site+on+the+Daini-Atsumi+Knoll+in+the+eastern+Nankai+Trough,+Japan.">Geological setting and characterization of a methane hydrate reservoir distributed at the first offshore production test site on the Daini-Atsumi Knoll in the eastern Nankai Trough, Japan.</a> Mar. Petrol. Geol. 66 (Pt 2), 310 (2015).</li><li>Mao, W. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrogen+clusters+in+clathrate+hydrate.">Hydrogen clusters in clathrate hydrate.</a> Science. 297 (5590), 2247-2249 (2002).</li><li>Lee, S., Liang, L., Riestenberg, D., West, O. R., Tsouris, C., Adams, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CO2+hydrate+composite+for+ocean+carbon+sequestration.">CO2 hydrate composite for ocean carbon sequestration.</a> Environ. Sci. Technol. 37 (16), 3701-3708 (2003).</li><li>Muromachi, S., Ohmura, R., Takeya, S., Mori, H. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clathrate+Hydrates+for+Ozone+Preservation.">Clathrate Hydrates for Ozone Preservation.</a> J. Phys. Chem. B. 114, 11430-11435 (2010).</li><li>Waite, W. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Physical+properties+of+hydrate-bearing+sediments.">Physical properties of hydrate-bearing sediments.</a> Rev. Geophys. 47 (4), (2009).</li><li>Muraoka, M., Susuki, N., Yamaguchi, H., Tsuji, T., Yamamoto, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermal+properties+of+a+supercooled+synthetic+sand-water-gas-methane+hydrate+sample.">Thermal properties of a supercooled synthetic sand-water-gas-methane hydrate sample.</a> Energy Fuels. 29 (3), 1345-1351 (2015).</li><li>Gustafsson, S. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transient+plane+source+techniques+for+thermal+conductivity+and+thermal+diffusivity+measurements+of+solid+materials.">Transient plane source techniques for thermal conductivity and thermal diffusivity measurements of solid materials.</a> Rev. Sci. Instrum. 62 (3), 797-804 (1991).</li><li>Sakamoto, Y., Haneda, H., Kawamura, T., Aoki, K., Komai, T., Yamaguchi, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+Study+on+a+New+Enhanced+Gas+Recovery+Method+by+Nitrogen+Injection+from+a+Methane+Hydrate+Reservoir.">Experimental Study on a New Enhanced Gas Recovery Method by Nitrogen Injection from a Methane Hydrate Reservoir.</a> J. MMIJ. 123 (8), 386-393 (2007).</li><li>Lee, B. I., Kesler, M. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+generalized+thermodynamic+correlation+based+on+three-parameter+corresponding+states.">A generalized thermodynamic correlation based on three-parameter corresponding states.</a> AIChE J. 21 (3), 510-527 (1975).</li><li>Reid, R. C., Prausnitz, J. M., Poling, B. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chapter+3,+Unit+3,+7.">Chapter 3, Unit 3, 7.</a> The properties of gases and liquids. , 47-49 (1987).</li><li>Anderson, G. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enthalpy+of+dissociation+and+hydration+number+of+methane+hydrate+from+the+Clapeyron+equation.">Enthalpy of dissociation and hydration number of methane hydrate from the Clapeyron equation.</a> J. Chem. Thermodyn. 36 (12), 1119-1127 (2004).</li><li>Waite, W. F., deMartin, B. J., Kirby, S. H., Pinkston, J., Ruppel, C. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermal+conductivity+measurements+in+porous+mixtures+of+methane+hydrate+and+quartz+sand.">Thermal conductivity measurements in porous mixtures of methane hydrate and quartz sand.</a> Geophys. Res. Lett. 29 (24), 82-1-82-4 (2002).</li><li>Kumar, P., Turner, D., Sloan, E. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermal+diffusivity+measurements+of+porous+methane+hydrate+and+hydrate-sediment+mixtures.">Thermal diffusivity measurements of porous methane hydrate and hydrate-sediment mixtures.</a> J. Geophys. Res. 109 (B1), (2004).</li><li>Huang, D., Fan, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+and+modeling+thermal+conductivity+of+gas+hydrate-bearing+sand.">Measuring and modeling thermal conductivity of gas hydrate-bearing sand.</a> J. Geophys. Res. 110 (B1), (2005).</li></ol>

The authors have nothing to disclose.

The effect of the formation heat of MH on measurement was estimated. The formation heat of MH was estimated from products of change rate of Sh as shown in Figure 3b and the enthalpy of formation H = 52.9 kJ mol&#8722;1 for MH14. Consequently, the maximum temperature change was 0.00081 &#176;C sec&#8722;1. This was much lower than the temperature increase &#916;Tc of the TPS sensor between 1 &#176;C and 1.5 &#176;C during th...

Gas hydrates are crystalline compounds that comprise cage structures of hydrogen-bonded water molecules containing guest molecules in the cage1. Large amounts of methane hydrates (MHs) in the ocean floor and permafrost regions are interesting future energy resources but may affect global climate conditions2.
In March 2013, the Japan Oil, Gas, and Metals National Corporation conducted the world&#39;s first offshore production test to extract gas from natural MH-bearing sediments in the eastern Nankai Trough using the &#34;depressurization method&#34; 3,4.
Gas hydrates can store gases such as methane1, hydrogen5, CO21,6, and ozone7. Hence, methane and hydrogen hydrates are studied as potential energy storage and transportation media. To reduce the CO2 emissions released into the atmosphere, CO2 sequestration using CO2 hydrates in deep-ocean sediments have been studied6. Ozone is currently used in water purification and food sterilization. Studies of ozone preservation technology have been conducted because it is chemically unstable7. The ozone concentration in hydrates is much higher than that in ozonized water or ice7.
To develop gas production from natural MH-bearing sediments and hydrate-based technologies, it is imperative to understand the thermal properties of gas hydrates. However, the thermal properties data and model studies of gas hydrate-bearing sediments are scarce8.
The &#34;depressurization method&#34; can be used to dissociate MH in the sediment pore space by decreasing the pore pressure below the hydrate stability. In this process, the sediment pore space components change from water and from MH to water, MH, and gas. The thermal properties&#39; measurement of the latter condition is difficult because the melting heat of MH may affect the measurements. To solve this problem, Muraoka et al. performed the thermal properties&#39; measurement at supercooled conditions during MH formation9.
With this video protocol, we explain the measuring method of supercooled synthetic sand-water-gas-MH sample.
Figure 1 shows the experimental setup for measuring the thermal properties of the artificial methane hydrate-bearing sediment. The setup is the same as shown in reference9. The system mainly comprises a high-pressure vessel, pressure and temperature control, and thermal properties of the measurement system. The high-pressure vessel is composed of cylindrical stainless steel with an internal diameter of 140 mm and a height of 140 mm; its inner volume with the dead volume removed is 2,110 cm3, and its pressure limit is 15 MPa. The transient plane source (TPS) technique is used to measure the thermal properties10. Nine TPS probes with individual radii of 2.001 mm are placed inside the vessel. The layout of the nine probes9 is shown in Figure 2 in reference9. The TPS probes are connected to the thermal properties&#39; analyzer with a cable and switched manually during the experiment. The details of the TPS sensor, connection diagram, and setup in the vessel are shown in Figures S1, 2, and 3 of the supporting information in reference9.
<img alt="Figure 1" src="/files/ftp_upload/53956/53956fig1.jpg" /> 
Figure 1: The experimental setup for measuring the thermal properties of the artificial methane hydrate-bearing sediment. The figure is modified from&#160;reference9. <a href="https://www.jove.com/files/ftp_upload/53956/53956fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
The TPS method was used to measure the thermal properties of each sample. The method principles are described in reference10. In this method, the time-dependent temperature increase, &#916;Tave, is
<img alt="Equation 1" src="/files/ftp_upload/53956/53956eq1.jpg" />
where
<img alt="Equation 2" src="/files/ftp_upload/53956/53956eq2.jpg" />
In Equation 1, W0 is the output power from the sensor, r is the radius of the sensor probe, &#955; is the thermal conductivity of the sample, &#945; is the thermal diffusivity, and t is the time from the start of the power supply to the sensor probe. D(&#964;) is a dimensionless time dependent function. &#964; is given by (&#945;t/r)1/2. In Equation 2, m is the number of concentric rings of the TPS probe and I0 is a modified Bessel function. The thermal conductivity, thermal diffusivity, and specific heat of the sample are simultaneously determined by inversion analysis applied to the temperature increase as power is supplied to the sensor probe.

<table><tbody><tr><td>TPS thermal probe, Hot disk sensor</td><td>Hot Disk AB Co., Sweden</td><td>#7577</td><td>Kapton sensor type, sensor radius 2.001 mm</td></tr><tr><td>Hot disk thermal properties analyzer</td><td>Hot Disk AB Co., Sweden</td><td>TPS 2500&amp;nbsp;</td><td></td></tr><tr><td>Toyoura standard silica sand</td><td>Toyoura Keiseki Kogyo Co., Ltd., Japan</td><td>N/A</td><td></td></tr><tr><td>Methane gas, 99.9999%</td><td>Tokyo Gas Chemicals Co., Ltd., Japan</td><td>N/A</td><td>Grade 6&amp;nbsp;N, Volume 47&amp;nbsp;L, Charging pressure 14.7&amp;nbsp;MPa</td></tr><tr><td>Water Purification System, Elix Advantage 3</td><td>Merck Millipore., U.S.</td><td>N/A</td><td>5 M&amp;Omega; cm (at 25&amp;nbsp;&amp;deg;C) resistivity</td></tr><tr><td>Vibrating table, Vivratory packer</td><td>Sinfonia Technology Co. Ltd., Japan</td><td>VGP-60</td><td></td></tr><tr><td>Chiller, Thermostatic Bath Circulator&amp;nbsp;</td><td>THOMAS KAGAKU Co., Ltd., Japan</td><td>TRL-40SP</td><td></td></tr><tr><td>Coorant, Aurora brine</td><td>Tokyo Fine Chemical Co.,Ltd., Japan</td><td>N/A</td><td>ethylene glycol 71&amp;nbsp;wt%</td></tr><tr><td>Temparature gage</td><td>Nitto Kouatsu., Japan</td><td>N/A</td><td>Pt 100, sheath-type platinum resistance temperature detector</td></tr><tr><td>Pressure gage</td><td>Kyowa Electronic Instruments., Japan</td><td>PG-200 KU</td><td></td></tr><tr><td>Data logger</td><td>KEYENCE., Japan</td><td>NR-500</td><td></td></tr><tr><td>Mass flow controller</td><td>OVAL Co., Japan</td><td>F-221S-A-11-11A</td><td>Maximum flow 2,000&amp;nbsp;N&amp;nbsp;ml&amp;#8288;/&amp;#8288;M, maximum design pressure 19.6&amp;nbsp;MPa</td></tr></tbody></table>

protocol for measuring the thermal properties of a supercooled synthetic sand-water-gas-methane hydrate sample

Methane hydrates (MHs) are present in large amounts in the ocean floor and permafrost regions. Methane and hydrogen hydrates are being studied as future energy resources and energy storage media. To develop a method for gas production from natural MH-bearing sediments and hydrate-based technologies, it is imperative to understand the thermal properties of gas hydrates.
The thermal properties' measurements of samples comprising sand, water, methane, and MH are difficult because the melting heat of MH may affect the measurements. To solve this problem, we performed thermal properties' measurements at supercooled conditions during MH formation. The measurement protocol, calculation method of the saturation change, and tips for thermal constants' analysis of the sample using transient plane source techniques are described here.
The effect of the formation heat of MH on measurement is very small because the gas hydrate formation rate is very slow. This measurement method can be applied to the thermal properties of the gas hydrate-water-guest gas system, which contains hydrogen, CO2, and ozone hydrates, because the characteristic low formation rate of gas hydrate is not unique to MH. The key point of this method is the low rate of phase transition of the target material. Hence, this method may be applied to other materials having low phase-transition rates.

Figure 2a shows the temperature profile that is not affected by MH melting. &#916;Tc is the temperature change due to thermal constants&#39; measurement. Figure 2b shows the temperature profile that is affected by MH melting. The profile in Figure 2b cannot be analyzed through Equations 1 and 2 because these equations are derived by assuming stable sample conditions.
<p class="jove_content" fo:keep-together.within-...

Watch this Scientific Journal Video about Protocol for Measuring the Thermal Properties of a Supercooled Synthetic Sand-water-gas-methane Hydrate Sample at JoVE.com

Protocol for Measuring the Thermal Properties of a Supercooled Synthetic Sand-water-gas-methane Hydrate Sample

We present a protocol for measuring the thermal properties of synthetic hydrate-bearing sediment samples comprising sand, water, methane, and methane hydrate.

Methane hydrates (MHs) are present in large amounts in the ocean floor and permafrost regions. Methane and hydrogen hydrates are being studied as future ...

protocol-for-measuring-thermal-properties-supercooled-synthetic-sand

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8.8K Views.  National Institute of Advanced Industrial Science and Technology (AIST). We present a protocol for measuring the thermal properties of synthetic hydrate-bearing sediment samples comprising sand, water, methane, and methane hydrate.

Video: Protocol for Measuring the Thermal Properties of a Supercooled Synthetic Sand-water-gas-methane Hydrate Sample

Metal-silicate Partitioning at High Pressure and Temperature: Experimental Methods and a Protocol to Suppress Highly Siderophile Element Inclusions

Estimates of the primitive upper mantle (PUM) composition reveal a depletion in many of the siderophile (iron-loving) elements, thought to result from their extraction to the core during terrestrial accretion. Experiments to investigate the partitioning of these elements between metal and silicate melts suggest that the PUM composition is best matched if metal-silicate equilibrium occurred at high pressures and temperatures, in a deep magma ocean environment. The behavior of the most highly siderophile elements (HSEs) during this process however, has remained enigmatic. Silicate run-products from HSE solubility experiments are commonly contaminated by dispersed metal inclusions that hinder the measurement of element concentrations in the melt. The resulting uncertainty over the true solubility and metal-silicate partitioning of these elements has made it difficult to predict their expected depletion in PUM. Recently, several studies have employed changes to the experimental design used for high pressure and temperature solubility experiments in order to suppress the formation of metal inclusions. The addition of Au (Re, Os, Ir, Ru experiments) or elemental Si (Pt experiments) to the sample acts to alter either the geometry or rate of sample reduction respectively, in order to avoid transient metal oversaturation of the silicate melt. This contribution outlines procedures for using the piston-cylinder and multi-anvil apparatus to conduct solubility and metal-silicate partitioning experiments respectively. A protocol is also described for the synthesis of uncontaminated run-products from HSE solubility experiments in which the oxygen fugacity is similar to that during terrestrial core-formation. Time-resolved LA-ICP-MS spectra are presented as evidence for the absence of metal-inclusions in run-products from earlier studies, and also confirm that the technique may be extended to investigate Ru. Examples are also given of how these data may be applied.

We present a procedure to determine the metal-silicate partitioning of siderophile elements, emphasizing techniques that suppress the formation of metal inclusions in experiments for the noble metals. The results of these experiments are used to demonstrate the effect of core-formation on the highly siderophile element composition of the mantle.

Estimates of the primitive upper mantle (PUM) composition reveal a depletion in many of the siderophile (iron-loving) elements, thought to result from ...

Chemistry

Thermal Scanning Conductometry (TSC) as a General Method for Studying and Controlling the Phase Behavior of Conductive Physical Gels

The thermal scanning conductometry protocol is a new approach in studying ionic gels based on low molecular weight gelators. The method is designed to follow the dynamically changing state of the ionogels, and to deliver more information and details about the subtle change of conductive properties with an increase or decrease in the temperature. Moreover, the method allows the performance of long term (i.e. days, weeks) measurements at a constant temperature to investigate the stability and durability of the system and the aging effects. The main advantage of the TSC method over classical conductometry is the ability to perform measurements during the gelation process, which was impossible with the classical method due to temperature stabilization, which usually takes a long time before the individual measurement. It is a well-known fact that to obtain the physical gel phase, the cooling stage must be fast; moreover, depending on the cooling rate, different microstructures can be achieved. The TSC method can be performed with any cooling/heating rate that can be assured by the external temperature system. In our case, we can achieve linear temperature change rates between 0.1 and approximately 10 &#176;C/min. The thermal scanning conductometry is designed to work in cycles, continuously changing between heating and cooling stages. Such an approach allows study of the reproducibility of the thermally reversible gel-sol phase transition. Moreover, it allows the performance of different experimental protocols on the same sample, which can be refreshed to initial state (if necessary) without removal from the measuring cell. Therefore, the measurements can be performed faster, in a more efficient way, and with much higher reproducibility and accuracy. Additionally, the TSC method can be also used as a tool to manufacture the ionogels with targeted properties, like microstructure, with an instant characterization of conductive properties.

Thermal Scanning Conductometry TSC as a General Method for Studying and Controlling the Phase Behavior of Conductive Physical Gels

The kinetics of the cooling process defines the properties of ionic gels based on low molecular weight gelators. This manuscript describes the usage of thermal scanning conductometry (TSC), which obtains full control over the gelation process, along with in situ measurements of the samples' temperature and conductivity.

The thermal scanning conductometry protocol is a new approach in studying ionic gels based on low molecular weight gelators. The method is designed to ...

Experimental Study of the Relationship Between Particle Size and Methane Sorption Capacity in Shale

The amount of adsorbed shale gas is a key parameter used in shale gas resource evaluation and target area selection, and it is also an important standard for evaluating the mining value of shale gas. Currently, studies on the correlation between particle size and methane adsorption are controversial. In this study, an isothermal adsorption apparatus, the gravimetric sorption analyzer, is used to test the adsorption capacity of different particle sizes in shale to determine the relationship between the particle size and the adsorption capacity of shale. Thegravimetric method requires fewer parameters and produces better results in terms of accuracy and consistency than methods like the volumetric method. Gravimetric measurements are performed in four steps: a blank measurement, preprocessing, a buoyancy measurement, and adsorption and desorption measurements. Gravimetric measurement is presently considered to be a more scientific and accurate method of measuring the amount of adsorption; however, it is time-consuming and requires a strict measuring technique. A Magnetic Suspension Balance (MSB) is the key to verify the accuracy and consistency of this method. Our results show that adsorption capacity and particle size are correlated, but not a linear correlation, and the adsorptions in particles sieved into 40 - 60 and 60 - 80 meshes tend to be larger. We propose that the maximum adsorption corresponding to the particle size is approximately 250 &#181;m (60 mesh) in the shale gas fracturing.

We use an isothermal adsorption apparatus, the gravimetric sorption analyzer, to test the adsorption capacity of different particle sizes of shale, in order to find out the relationship between particle size and the adsorption capacity of shale.

The amount of adsorbed shale gas is a key parameter used in shale gas resource evaluation and target area selection, and it is also an important standard ...

An Experimental Protocol for Studying Mineral Effects on Organic Hydrothermal Transformations

Organic-mineral interactions are widely occurring in hydrothermal environments, such as hot springs, geysers on land, and the hydrothermal vents in the deep ocean. Roles of minerals are critical in many hydrothermal organic geochemical processes. Traditional hydrothermal methodology, which includes using reactors made of gold, titanium, platinum, or stainless-steel, is usually associated with the high cost or undesired metal catalytic effects. Recently, there is a growing tendency for using the cost-effective and inert quartz or fused silica glass tubes in hydrothermal experiments. Here, we provide a protocol for carrying out organic-mineral hydrothermal experiments in silica tubes, and we describe the essential steps in the sample preparation, experimental setup, products separation, and quantitative analysis. We also demonstrate an experiment using a model organic compound, nitrobenzene, to show the effect of an iron-containing mineral, magnetite, on its degradation under a specific hydrothermal condition. This technique can be applied to study complex organic-mineral hydrothermal interactions in a relatively simple laboratory system.

Earth-abundant minerals play important roles in the natural hydrothermal systems. Here, we describe a reliable and cost-effective method for the experimental investigation of organic-mineral interactions under hydrothermal conditions.

Organic-mineral interactions are widely occurring in hydrothermal environments, such as hot springs, geysers on land, and the hydrothermal vents in the ...

Methane Hydrate Crystallization on Sessile Water Droplets

This paper describes a method to form methane hydrate shells on water droplets. In addition, it provides blueprints for a pressure cell rated to 10 MPa working pressure, containing a stage for sessile droplets, a sapphire window for visualization, and temperature and pressure transducers. A pressure pump connected to a methane gas cylinder is used to pressurize the cell to 5 MPa. The cooling system is a 10 gallon (37.85 L) tank containing a 50% ethanol solution cooled via ethylene glycol through copper coils. This setup enables the observation of the temperature change associated with hydrate formation and dissociation during cooling and depressurization, respectively, as well as visualization and photography of the morphologic changes of the droplet. With this method, rapid hydrate shell formation was observed at ~-6 &#176;C to -9 &#176;C. During depressurization, a 0.2 &#176;C to 0.5 &#176;C temperature drop was observed at the pressure/temperature (P/T) stability curve due to exothermic hydrate dissociation, confirmed by visual observation of melting at the start of the temperature drop. The "memory effect" was observed after repressurizing to 5 MPa from 2 MPa. This experimental design allows the monitoring of pressure, temperature, and morphology of the droplet over time, making this a suitable method for testing various additives and substrates on hydrate morphology.

We describe a method to form gas hydrate on sessile water droplets to study the effects of various inhibitors, promoters, and substrates on the hydrate crystal morphology.

This paper describes a method to form methane hydrate shells on water droplets. In addition, it provides blueprints for a pressure cell rated to 10 MPa ...

Surface Properties of Synthesized Nanoporous Carbon and Silica Matrices

In this work, we report the synthesis and characterization of ordered nanoporous carbon material (also called ordered mesoporous carbon material [OMC]) with a 4.6 nm pore size, and ordered silica porous matrix, SBA-15, with a 5.3 nm pore size. This work describes the surface properties of nanoporous molecular sieves, their wettability, and the melting behavior of D2O confined in the differently ordered porous materials with similar pore sizes. For this purpose, OMC and SBA-15 with highly ordered nanoporous structures are synthesized via impregnation of the silica matrix by applying a carbon precursor and by the sol-gel method, respectively. The porous structure of investigated systems is characterized by an N2 adsorption-desorption analysis at 77 K. To determine the electrochemical character of the surface of synthesized materials, potentiometric titration measurements are conducted; the obtained results for OMC shows a significant pHpzc shift toward the higher values of pH, relative to SBA-15. This suggests that investigated OMC has surface properties related to oxygen-based functional groups. To describe the surface properties of the materials, the contact angles of liquids penetrating the studied porous beds are also determined. The capillary rise method has confirmed the increased wettability of the silica walls relative to the carbon walls and an influence of the pore roughness on the fluid/wall interactions, which is much more pronounced for silica than for carbon mesopores. We have also studied the melting behavior of D2O confined in OMC and SBA-15 by applying the dielectric method. The results show that the depression of the melting temperature of D2O in the pores of OMC is about 15 K higher relative to the depression of the melting temperature in SBA-15 pores with a comparable 5 nm size. This is caused by the influence of adsorbate/adsorbent interactions of the studied matrices.

Here we report the synthesis and characterization of ordered nanoporous carbon (with a 4.6 nm pore size) and SBA-15 (with a 5.3 nm pore size). The work describes the surface and textural properties of nanoporous molecular sieves, their wettability, and the melting behavior of D2O confined in the materials.

In this work, we report the synthesis and characterization of ordered nanoporous carbon material (also called ordered mesoporous carbon material [OMC]) ...

Studying Surfactant Effects on Hydrate Crystallization at Oil-Water Interfaces Using a Low-Cost Integrated Modular Peltier Device

We introduce an approach to study the formation and growth of hydrates under the influence of nonionic surfactants. The experimental system includes a temperature regulator, visualization techniques, and inner pressure measurements. The temperature control system contains a low-cost, programmable temperature regulator made with solid-state Peltier components. Along with the temperature control system, we incorporated visualization techniques and internal pressure measurements to study hydrate formation and inhibition in the presence of nonionic surfactants. We studied the hydrate-inhibiting ability of nonionic surfactants (sorbitane monolaurate, sorbitane monooleate, PEG-PPG-PEG, and polyoxyethylenesorbitan tristearate) at low (i.e., 0.1 CMC), medium (i.e., CMC), and high (i.e., 10 CMC) concentrations. Two types of crystals were formed: planar and conical. Planar crystals were formed in plain water and low surfactant concentrations. Conical crystals were formed in high surfactant concentrations. The results of the study show that conical crystals are the most effective in terms of hydrate inhibition. Because conical crystals cannot grow past a certain size, the hydrate growth rate as a conical crystal is slower than the hydrate growth rate as planar crystal. Hence, surfactants that force hydrates to form conical crystals are the most efficient. The goal of the protocol is to provide a detailed description of an experimental system that is capable of investigating the cyclopentane hydrate crystallization process on the surface of a water droplet in the presence of surfactant molecules.

We present a protocol to study the formation of hydrates in the presence of nonionic surfactants on the interface of a water droplet submerged in cyclopentane. The protocol consists of building a low-cost, programmable, temperature regulator. The temperature control system is combined with visualization techniques and internal pressure measurements.

We introduce an approach to study the formation and growth of hydrates under the influence of nonionic surfactants. The experimental system includes a ...

Measuring Electrical Conductivity to Study the Formation of Brines Under Martian Conditions

This paper describes a protocol to design experiments to study the formation of brines under Martian conditions and monitor the process with electrical conductivity measurements. We used the Engineering Qualification Model (EQM) of Habitability: Brines, Irradiation, and Temperature (HABIT)/ExoMars 2022 instrument for the experiment setup but we provide a brief account of constructing a simple and inexpensive electrical conductivity measurement setup. The protocol serves to calibrate the electrical conductivity measurements of the salt deliquescence into brine in a simulated Martian environment. The Martian conditions of temperature (-70 &#176;C to 20 &#176;C), relative humidity (0% to 100%) and pressure (7 - 8 mbar) with carbon-dioxide atmosphere were simulated in the SpaceQ Mars simulation chamber, a facility at the Lule&#229; University of Technology, Sweden. The hydrate form of the known amount of salt accommodated between a pair of electrodes and thus the electrical conductivity measured depends predominantly on its water content and the temperature and relative humidity of the system. Electrical conductivity measurements were carried out at 1 Hz while exposing salts to a continuously increasing relative humidity (to force transitioning through various hydrates) at different Martian temperatures. For demonstration, a day-night cycle at Oxia Planum, Mars (the landing site of ExoMars 2022 mission) was recreated.

The objective of the protocol is to monitor the hydration of salts and the brine formation process. Electrical conductivity is used as the measurement technique. The experiments are performed in a simulated Martian environment of temperature, relative humidity and carbon-dioxide atmosphere.

This paper describes a protocol to design experiments to study the formation of brines under Martian conditions and monitor the process with electrical ...

A Microfluidic Approach for the Study of Ice and Clathrate Hydrate Crystallization

An accurate mechanistic description of water crystallization is challenging and requires a few key elements: superb temperature control to allow the formation of single microscopic crystals and a suitable microscopy system coupled to the cold stage. The method described herein adds another important feature that includes exchanging solutions around ice and clathrate hydrate crystals. The described system comprises a combination of unique and home-developed instruments, including microfluidics, high-resolution cold stages, and fluorescence microscopy. The cold stage was designed for microfluidic devices and allows for the formation of micron-sized ice/hydrate crystals inside microfluidic channels and the exchange of solutions around them. The temperature resolution and stability of the cold stage is one millikelvin, which is crucial for controlling the growth of these small crystals. This diverse system is used to study the different processes of ice and hydrate crystallization and the mechanism by which the growth of these crystals is inhibited. The protocol describes how to prepare microfluidic devices, how to grow and control microscopic crystals in the microfluidic channels, and how the utilization of the flow of liquids around ice/hydrate crystals affords new insights into the crystallization of water.

The present protocol describes the crystallization of microscopic ice crystals and clathrate hydrates in microfluidic devices, enabling liquid exchange around the formed crystals. This provides unparalleled possibilities to examine the crystallization process and binding mechanisms of the inhibitors.

An accurate mechanistic description of water crystallization is challenging and requires a few key elements: superb temperature control to allow the ...

Impregnation and Grafting of Aminated Compounds onto Silica Substrates

A Synthetic Methodology for Preparing Impregnated and Grafted Amine-Based Silica Composites for Carbon Capture

Recently, there has been a significant effort towards reducing or mitigating CO2 emissions through the use of carbon capture materials for point source or direct air capture (DAC) methods. This work focuses on amine-functionalized CO2 adsorbents for DAC. These materials show promise for CO2 removal because they have low regeneration energy consumption and high adsorption capacity. The incorporation of amine species into a porous substrate combines the advantages of the amine species&#39; affinity to CO2 with the large pore volumes and surface areas of the porous substrate. There are three methods commonly used to prepare amine-based CO2 sorbents, depending on the selection of the amine species, material support, and preparation method. These methods are impregnation, grafting, or chemical synthesis. Silica is a prevalent choice of substrate material because of its adjustable pore size, moisture tolerance, temperature stability, and ability to adsorb CO2 in low concentrations for DAC applications. Typical synthetic procedures and primary attributes of both impregnated and grafted amine-silica composites are described herein.

Author Spotlight: Standardizing the Development of Amine-Based Silica Composites as CO2 Adsorbents for Direct Air Capture 

This work aims to facilitate the development of standardized techniques for impregnating or grafting aminated compounds onto silica substrates, which are often broadly described in the literature. Specific amounts of solvent, substrate, amines, and the values of other important experimental parameters will be discussed in detail.

Recently, there has been a significant effort towards reducing or mitigating CO2 emissions through the use of carbon capture materials for point source or ...

Protocol for Measuring the Thermal Properties of a Supercooled Synthetic Sand-water-gas-methane Hydrate Sample

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