The first experience the transportation of deep-water methane hydrates in a container

Егоров, А. В.; Римский-Корсаков, Н.А.; Рожков, А. Н.; Chernyaev, E. S.

doi:10.1134/s0001437011020068

Cited by 5 publications

(10 citation statements)

References 1 publication

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“…At the temperature of the waters of Lake Baikal, that is, T = 3.5°C, the critical phase transition pressure p s is p s = p a + ρ gz s = 3.8278 MPa, where z s = 380 m is the upper boundary of the HSZ (Egorov et al . ). Substituting p 1 = p s (=ρ gz s , p a ≪ ρ gz s ) into (9) determines the maximum envelope radius R s at which further growth of the hydrate in the bubble stops due to thermodynamic instability:

R_{s} = {(false(1 - z_{0} false/ z^{*} false) / false(1 - z_{s} false/ z_{*} false))}^{1 / 3},

that is R s = R f /(1− z s / z * ) 1/3 = R f /0.9180 for the conditions of Lake Baikal.…”

Section: Discussionmentioning

confidence: 97%

“…At pressure p s , any additionally formed hydrate decreases the pressure in the bubble below p s , and therefore, the additional hydrate decomposes immediately. At the temperature of the waters of Lake Baikal, that is, T = 3.5°C, the critical phase transition pressure p s is p s = p a + qgz s = 3.8278 MPa, where z s = 380 m is the upper boundary of the HSZ (Egorov et al 2011). Substituting p 1 = p s (=qgz s , p a ( qgz s ) into (9) determines the maximum envelope radius R s at which further growth of the hydrate in the bubble stops due to thermodynamic instability:…”

Section: First Controlling Factor Of Bubble Transformationmentioning

confidence: 99%

“…Preliminary results were published by Egorov et al (2010), Egorov et al (2011) and Egorov et al (2012). Current paper presents only new photographs obtained from video records in other moments of time.…”

Section: Introductionmentioning

confidence: 99%

“…To collect the gas bubbles several versions of traps were used -Fig. 2 (Egorov et al 2010;Egorov et al 2011;Egorov et al 2012). Trap "Funnel" is an inverted glass, into which the funnel is inserted.…”

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confidence: 99%

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Transformation of deep‐water methane bubbles into hydrate

2014

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The paper is dedicated to the mechanics of the methane bubbles in the gas hydrate stability zone of the basin. Transformation of deep-water methane bubbles into solid hydrate was investigated in Lake Baikal in situ. Released from the bottom methane bubbles were caught by different traps with transparent walls. It was observed that when bubbles entered into internal space of the trap, the bubbles could be transformed into two different solid hydrate structures depending on ambient conditions. The first structure is hydrate granular matter consisted of solid fragments with sizes of order of 1 mm. The second structure is high porous solid foam consisted of solid bubbles with sizes of order of 5 mm. The formed granular matter did not change during trap lifting up to top border of gas hydrate stability zone, whereas free methane intensively released from solid foam sample during it lifting. It was concluded that the decrease of the depth of bubble sampling and the decrease of the bubble flux rate assist to formation of hydrate granular matter, whereas increase of the depth of bubble sampling and growth of bubble flux rate assist to conversation of bubbles into high porous solid hydrate foam.

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R_{s} = {(false(1 - z_{0} false/ z^{*} false) / false(1 - z_{s} false/ z_{*} false))}^{1 / 3},

that is R s = R f /(1− z s / z * ) 1/3 = R f /0.9180 for the conditions of Lake Baikal.…”

Section: Discussionmentioning

confidence: 97%

Section: First Controlling Factor Of Bubble Transformationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Transformation of deep‐water methane bubbles into hydrate

2014

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“…The samples (fragments) of hydrate were excavated from monolithic hydrate deposit by means of mechanical arm of manned submersible (MS) 'Mir'. The samples were placed in the non-sealed container and delivered to the surface (Egorov et al, 2011). The container had grid-like bottom, so the mass exchange between the container content and the ambient media could be possible only through grid-like bottom.…”

Section: Introductionmentioning

confidence: 99%

Temperature effects in deep-water gas hydrate foam

2018

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This study focuses on heat and mass exchange processes in hydrate foam during its formation from methane bubbles in gas hydrate stability zone (GHSZ) of the Lake Baikal and following delivery of it in open container to the lake surface. The foam was formed as a result of methane bubble collection with a trap/container. The trap was inverted glass beaker of diameter of 70 mm and 360 mm long. Open bottom end of the beaker used as enter for bubbles ascended from the lakebed. At a depth of 1400 m all bubbles which fed to the trap were transformed here into solid hydrate foam. The sensitive thermometer was mounted in the middle of the trap and recorded the temperature inside trap. The fate of the bubbles in the trap was recorded by video-camera. Hydrate front, i.e. the border between forming hydrate foam and pure water, propagated slowly from the top to the bottom of the trap during bubbles collection. The temperature in the trap was slightly larger (by 0.05 o C) than the temperature of ambient water.However as soon as the front crossed the location of temperature sensor, the temperature jump by ~+1.1 o C was recorded. After that during 3 hours the temperature exponentially relaxes to an asymptotic magnitude which however exceeded the temperature of ambient water by 0.3 o C. Thus hydrate foam formation occurs with heat dissipation with maximal intensity on hydrate front. The dissipation does not stop within hydrate volume at the constant depth of 1400 m during at least of 3 hours. After bubbles collection the trap with the foam was ascended from the lakebed to the surface, initially within GHSZ and then above GHSZ. During ascend within GHSZ with velocity about 0.375 m/s two remarkable features were observed. First one is displacement of the water from the trap by gas which was released from the foam sample under the decrease of the hydrostatic pressure. It was found that gas expansion follows to Boyle-Mariotte law in which initial volume of gas is equal approximately to volume of the foam sample. The second feature is continuous decrease of the temperature in the foam up to a level of negative magnitude in a depth interval of 1400 -750 meters. Above 750 m temperature decrease was changed by small growth. However once the trap ascended above top boundary of GHSZ at a depth of 380 m, the temperature fell sharply. Falling to a negative values -0.25 o C, the temperature sharply stabilized and did not changed further until the trap reached the surface. The decreasing of the temperature during the ascent is due to the cooling of gas as a result of the performing of the work against the forces of hydrostatic pressure. The temperature drop at the boundary of the GHSZ is due to the absorption of heat by the decomposition of hydrate. The keeping of the foam temperature at the constant level -0.25 o C above GHSZ reduces hydrate decomposition and is exhibition of effect of selfconservation of hydrate.

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