Estimation of Gas Hydrates in the Pore Space of Sediments Using Inversion Methods

Equilibrium Conditions of the Natural Gas Hydrates Formation in the Pore Space of Dispersed Rocks

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/666/4/042062 ◽

2021 ◽

Vol 666 (4) ◽

pp. 042062

Author(s):

L P Kalacheva ◽

I K Ivanova ◽

A S Portnyagin

Keyword(s):

Natural Gas ◽

Gas Hydrates ◽

Pore Space ◽

Equilibrium Conditions ◽

Natural Gas Hydrates

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Formation and Accumulation of Pore Methane Hydrates in Permafrost: Experimental Modeling

Geosciences ◽

10.3390/geosciences8120467 ◽

2018 ◽

Vol 8 (12) ◽

pp. 467 ◽

Cited By ~ 10

Author(s):

Evgeny Chuvilin ◽

Dinara Davletshina

Keyword(s):

Gas Hydrates ◽

Gas Hydrate ◽

Pore Space ◽

Hydrate Formation ◽

Methane Hydrates ◽

Frozen Soils ◽

Geological Models ◽

Negative Temperatures ◽

Thermobaric Conditions ◽

Ice Content

Favorable thermobaric conditions of hydrate formation and the significant accumulation of methane, ice, and actual data on the presence of gas hydrates in permafrost suggest the possibility of their formation in the pore space of frozen soils at negative temperatures. In addition, today there are several geological models that involve the formation of gas hydrate accumulations in permafrost. To confirm the literature data, the formation of gas hydrates in permafrost saturated with methane has been studied experimentally using natural artificially frozen in the laboratory sand and silt samples, on a specially designed system at temperatures from 0 to −8 °C. The experimental results confirm that pore methane hydrates can form in gas-bearing frozen soils. The kinetics of gas hydrate accumulation in frozen soils was investigated in terms of dependence on the temperature, excess pressure, initial ice content, salinity, and type of soil. The process of hydrate formation in soil samples in time with falling temperature from +2 °C to −8 °C slows down. The fraction of pore ice converted to hydrate increased as the gas pressure exceeded the equilibrium. The optimal ice saturation values (45−65%) at which hydrate accumulation in the porous media is highest were found. The hydrate accumulation is slower in finer-grained sediments and saline soils. The several geological models are presented to substantiate the processes of natural hydrate formation in permafrost at negative temperatures.

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Modeling of stability of gas hydrates under permafrost in an environment of surface climatic change – terrestrial case, Beaufort-Mackenzie basin, Canada

Climate of the Past Discussions ◽

10.5194/cpd-7-2863-2011 ◽

2011 ◽

Vol 7 (5) ◽

pp. 2863-2891

Author(s):

J. Majorowicz ◽

J. Šafanda ◽

K. Osadetz

Keyword(s):

Surface Temperature ◽

Gas Hydrates ◽

Gas Hydrate ◽

Pore Space ◽

Hydrate Formation ◽

Type I ◽

Depth Range ◽

Mackenzie Basin ◽

Gas Hydrate Formation ◽

Heat Effects

Abstract. Modeling of the onset of permafrost formation and succeeding gas hydrate formation in the changing surface temperature environment has been done for the Beaufort-Mackenzie Basin (BMB). Numerical 1-D modeling is constrained by deep heat flow from deep well bottom hole temperatures, deep conductivity, present permafrost thickness and thickness of Type I gas hydrates. Latent heat effects were applied to the model for the entire ice bearing permafrost and Type I hydrate intervals. Modeling for a set of surface temperature forcing during the glacial-interglacial history including the last 14 Myr was performed. Two scenarios of gas formation were considered; case 1: formation of gas hydrate from gas entrapped under deep geological seals and case 2: formation of gas hydrate from gas in a free pore space simultaneously with permafrost formation. In case 1, gas hydrates could have formed at a depth of about 0.9 km only some 1 Myr ago. In case 2, the first gas hydrate formed in the depth range of 290–300 m shortly after 6 Myr ago when the GST dropped from −4.5 °C to −5.5. °C. The gas hydrate layer started to expand both downward and upward subsequently. These models show that the gas hydrate zone, while thinning persists under the thick body of BMB permafrost through the current interglacial warming periods.

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Correlation of Pore Structure and Permeability by SEM-Image Analysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100180896 ◽

1990 ◽

Vol 48 (1) ◽

pp. 428-429

Author(s):

C. A. Callender ◽

Wm. C. Dawson ◽

J. J. Funk

Keyword(s):

Image Analysis ◽

Pore Structure ◽

Imaging System ◽

Pore Space ◽

Simulation Models ◽

Image Analyzer ◽

Imaging Data ◽

Sem Images ◽

Thin Sections ◽

Rock Types

The geometric structure of pore space in some carbonate rocks can be correlated with petrophysical measurements by quantitatively analyzing binaries generated from SEM images. Reservoirs with similar porosities can have markedly different permeabilities. Image analysis identifies which characteristics of a rock are responsible for the permeability differences. Imaging data can explain unusual fluid flow patterns which, in turn, can improve production simulation models.Analytical SchemeOur sample suite consists of 30 Middle East carbonates having porosities ranging from 21 to 28% and permeabilities from 92 to 2153 md. Engineering tests reveal the lack of a consistent (predictable) relationship between porosity and permeability (Fig. 1). Finely polished thin sections were studied petrographically to determine rock texture. The studied thin sections represent four petrographically distinct carbonate rock types ranging from compacted, poorly-sorted, dolomitized, intraclastic grainstones to well-sorted, foraminiferal,ooid, peloidal grainstones. The samples were analyzed for pore structure by a Tracor Northern 5500 IPP 5B/80 image analyzer and a 80386 microprocessor-based imaging system. Between 30 and 50 SEM-generated backscattered electron images (frames) were collected per thin section. Binaries were created from the gray level that represents the pore space. Calculated values were averaged and the data analyzed to determine which geological pore structure characteristics actually affect permeability.

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