Relations between methane venting, geological structure and seismo-tectonics in the Okhotsk Sea

Obzhirov, A.; Shakirov, R. B.; Salyuk, A.; Suess, Erwin; Biebow, Nicole; Salomatin, A.

doi:10.1007/s00367-004-0175-0

Cited by 77 publications

(60 citation statements)

References 2 publications

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“…Such structures are predominantly found in the Arctic (Kvenvolden et al 1993;Shakhova et al 2009). The molecule can move rapidly upward from sediments in the bubble phase (Obzhirov et al, 2004;Shakhova et al 2009). Therefore, concentrations build up beneath the ice pack, both in solution and as trapped pockets of vapor.…”

Section: Simulating Volatile Gas Productionmentioning

confidence: 99%

Sea Ice Biogeochemistry and Material Transport Across the Frozen Interface

Loose¹,

Miller²,

Elliott³

et al. 2011

Oceanog.

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Section: Simulating Volatile Gas Productionmentioning

confidence: 99%

Sea Ice Biogeochemistry and Material Transport Across the Frozen Interface

Loose¹,

Miller²,

Elliott³

et al. 2011

Oceanog.

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“…In period this investigation the first methane flux (1988) and gas hydrate (1991) was found [3,8]. After it many international expedition were provided on the Sakhalin shelf and slope of the Okhotsk Sea to search methane fluxes and gas hydrates [6,10,14].…”

Section: Results Of Investigation and Discussionmentioning

confidence: 97%

“…Geological, geophysical, gas geochemical, hydro-acoustic, morpho-structure surveys are very important indicators to search gas hydrates and to understand regularity forming and destroying of gas hydrates [10,11,12,14,16]. Thus, integrated complex of investigations with international cooperation allow us to discover methane fluxes, gas hydrates and to understand formation/dissociation gas hydrates in the Okhotsk Sea.…”

Section: Resultsmentioning

confidence: 99%

“…Multidisciplinary data were obtained during these expeditions: hydro-acoustic profiling using single-beam echosounders, seafloor imaging using side-scan sonar (SSS), seismic reflection profiling using a sub-bottom profiler and sparker-source seismic system, CTD profiling, water column sampling from bottom to surface using a Rosette sampler and near-bottom sediment and gas hydrate sampling using a gravity and hydro corer Gas bubbles in the water column have high impedance contrast relative to water and appear on echograms as hydro-acoustic sound-scattering anomalies like vertical flux (gas "flares") in water column from Sea floor to up in surface (figures 1a and 1b). The hydroacoustic systems 'ELAC' and/or 'Sargan-EM' were used simultaneously with frequencies of 12, 20, and 135 kHz to detect gas flares [2,10,14]. a b Deep-tow side-scan sonar surveys were conducted using the 'SONIC-3' system with a frequency of 30 kHz in a medium-range mode and a swath range of 800-3200 m. Width range is 500-2,000 m, and the best resolution is 2.0 m. The 'SONIC-3M' system is also equipped with a sub-bottom profiler with a frequency of 8 kHz (maximum resolution = 0.3 m).…”

Section: Methods Of Investigationsmentioning

confidence: 99%

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Gasgeochemical indicators seismic activity

Obzhirov

2017

E3S Web Conf.

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Abstract. Laboratory of Gasgeochemistry of POI FEB RAS is studying gas distribution in lithosphere, hydrosphere and atmosphere from 1977 years. Method consist is sampling from its in expedition, take gas from samples of sediment, water and atmosphere to use method degassing and analysis gas in chromatograph, to measure CH4, C2-C4, O2, N2, H2, He and some time Rn. Gas is using like indicators to search oil-gas deposits, gas hydrate, mapping zones faults, to determine seismic activity, to calculate green house gas (CH4, CO2). The next geological, geophysics and hydro-acoustics characteristics assist which help to explain to form methane bubbles fluxes and gas hydrate in the Okhotsk Sea. The methane fluxes are mostly located in the zones faults and it increase in period seismic activity.

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“…It has been proposed that free gas accumulation beneath the HSZ may reach a critical thickness to dilate fractures or activate pre-existing faults that will serve as conduits for fast upwards gas migration [Wood et al, 2002;Flemings et al, 2003;Trehu et al, 2004a;Hornbach et al, 2004;Zühlsdorff and Spiess, 2004;Obzhirov et al, 2004;Netzeband et al, 2005;Weinberger and Brown, 2006; Flemings, 2006, 2007]. Although they did not address the problem at the grain scale, Liu and Flemings [2007] also predicted that at fine grain size and high capillary entry pressure, fracture propagation would dominate the process as gas pressure exceeded the horizontal stress.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms Leading to Co-Existence of Gas Hydrate in Ocean Sediments [Part 2 of 2]

Bryant¹,

Juanes²

2011

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The experimental boundary conditions do not replicate the situation in gas reservoirs converted to hydrate in the Arctic. The key differences are that in the experiment water can move 117 to the hydrate stability zone only from below, while in nature water can move from below and from above. In experiment gas can move to the hydrate stability zone from below and from above, while in nature it can move only from below. Finally, the fluid phase pressures decrease with time in the experiment (though the conditions remain within the hydrate stability field throughout), while the water phase pressure does not change with time in nature. These differences are minor and do not alter the essential similarities to the natural situation. In the experiment and in nature, the base of the gas hydrate stability zone descends gradually through an existing gas accumulation, and fluid phases are free to move in response to any gradients that arise as hydrate forms. The latter point is important: no fluid flow (neither pressure-driven nor capillarity-driven) is imposed in the experiment. Instead the system evolves a combination of buoyancy-, pressure-and capillarity-driven fluxes of the gas and water phases, and these fluxes balance the various resistances to transport.The model predicts that the contribution of capillarity-driven flux is significant in these experiments. In fact R v~0 .69 when capillary-dominated flow is taken into account while R v~1 when only the viscous dominated portion of the flow was considered. This is consistent with our findings in previous sections of this report, namely, pressure-driven flow cannot supply water from below the BGHSZ fast enough to sustain hydrate formation. Moreover the model predicts that the amount of gas flows to the GHSZ from above quickly diminishes as both the effective permeability, due to hydrate formation within the GHSZ, and gaseous phase relative permeability, due to decrease in gas saturation within the GHSZ, decrease. Therefore, the main contribution for gas flow would be flow from the middle gas inlet. While the gas flux from above and from below could not be independently measured in this experiment, the consistency of the model with other observations suggests that all the fluids needed during conversion to hydrate can be supplied from below. But this is possible only if capillarity-driven flux is accounted for.The consistency of the capillarity-driven flux model with the experimental observations suggests that the finding in the previous section, viz. that the observed hydrate saturation profile in Mt. Elbert arises naturally from the capillarity-driven fluxes, is not a coincidence. That is, these findings suggest that the gas reservoir conversion process is slow, that it introduces modest, even negligible pressure gradients but impose significant gradients in saturation which, along with gas buoyancy, feed the appropriate volumes of fluids to the GHSZ.A complete validation of the model would compare the predicted hydrate saturation profile to the observed profile in F...

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Relations between methane venting, geological structure and seismo-tectonics in the Okhotsk Sea

Cited by 77 publications

References 2 publications

Sea Ice Biogeochemistry and Material Transport Across the Frozen Interface

Sea Ice Biogeochemistry and Material Transport Across the Frozen Interface

Gasgeochemical indicators seismic activity

Mechanisms Leading to Co-Existence of Gas Hydrate in Ocean Sediments [Part 2 of 2]

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