Natural Gas Hydrates—Energy Resource Potential and Associated Geologic Hazards

Collett, Timothy S.; Johnson, Arthur H.; Knapp, C. C.; Boswell, Ray

doi:10.1306/m891320

Cited by 110 publications

(76 citation statements)

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“…The impact of hydrate destabilization on climate change and its role as a future energy resource are widely debated Boswell and Collettt, 2011;Dickens, 2011;Ruppel, 2011;Hunter et al, 2013]. The origin of the gas-forming hydrates can be biogenic, thermogenic, or abiotic [Milkov, 2005;Collettt et al, 2009;Johnson et al, 2015].…”

Section: Introductionmentioning

confidence: 99%

Structure II gas hydrates found below the bottom‐simulating reflector

Paganoni

Cartwright

Foschi

et al. 2016

Geophysical Research Letters

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Gas hydrates are a major component in the organic carbon cycle. Their stability is controlled by temperature, pressure, water chemistry, and gas composition. The bottom‐simulating reflector (BSR) is the primary seismic indicator of the base of hydrate stability in continental margins. Here we use seismic, well log, and core data from the convergent margin offshore NW Borneo to demonstrate that the BSR does not always represent the base of hydrate stability and can instead approximate the boundary between structure I hydrates above and structure II hydrates below. At this location, gas hydrate saturation below the BSR is higher than above and a process of chemical fractionation of the migrating free gas is responsible for the structure I‐II transition. This research shows that in geological settings dominated by thermogenic gas migration, the hydrate stability zone may extend much deeper than suggested by the BSR.

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Section: Introductionmentioning

confidence: 99%

Structure II gas hydrates found below the bottom‐simulating reflector

Paganoni

Cartwright

Foschi

et al. 2016

Geophysical Research Letters

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“…Naturally occurring methane hydrate has been the subject of extensive research for many years due to its enormous potential as an unconventional gas resource [ Collett et al , 2009; Kvenvolden and Lorenson , 2001]. Recent field programs in the Nankai Trough [ Tsujii et al , 2009], Gulf of Mexico [ Boswell et al , 2010], and Alaska North Slope [ Hunter et al , 2011] have reported sand‐rich layers containing high saturations of methane hydrate.…”

Section: Introductionmentioning

confidence: 99%

Methane hydrate induced permeability modification for multiphase flow in unsaturated porous media

Seol

Kneafsey

2011

J. Geophys. Res.

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[1] An experimental study was performed using X-ray computed tomography (CT) scanning to capture three-dimensional (3-D) methane hydrate distributions and potential discrete flow pathways in a sand pack sample. A numerical study was also performed to develop and analyze empirical relations that describe the impacts of hydrate accumulation habits within pore space (e.g., pore filling or grain cementing) on multiphase fluid migration. In the experimental study, water was injected into a hydrate-bearing sand sample that was monitored using an X-ray CT scanner. The CT images were converted into numerical grid elements, providing intrinsic sample data including porosity and phase saturations. The impacts of hydrate accumulation were examined by adapting empirical relations into the flow simulations as additional relations governing the evolution of absolute permeability of hydrate bearing sediment with hydrate deposition. The impacts of pore space hydrate accumulation habits on fluid migration were examined by comparing numerical predictions with experimentally measured water saturation distributions and breakthrough curves. A model case with 3-D heterogeneous initial conditions (hydrate saturation, porosity, and water saturation) and pore body-preferred hydrate accumulations best captured water migration behavior through the hydrate-bearing sample observed in the experiment. In the best matching model, absolute permeability in the hydrate bearing sample does not decrease significantly with increasing hydrate saturation until hydrate saturation reaches about 40%, after which it drops rapidly, and complete blockage of flow through the sample can occur as hydrate accumulations approach 70%. The result highlights the importance of permeability modification due to hydrate accumulation habits when predicting multiphase flow through high-saturation, reservoir quality hydrate-bearing sediments.Citation: Seol, Y., and T. J. Kneafsey (2011), Methane hydrate induced permeability modification for multiphase flow in unsaturated porous media,

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“…This indicates that aqueous solubility is significantly altered in the presence of hydrate, where it decreases sharply with decreasing temperature once the temperature is below the triple point. The sudden decrease in solubility around the triple point allows hydrate to form directly from an aqueous solution without free gas present (Collett et al, 2009), a feature that can be exploited in the laboratory to mimic naturally-occurring hydrate in sediment (Buffett & Zatsepina, 2000;Priegnitz et al, 2015;Spangenberg & Kulenkampff, 2006;Waite & Spangenberg, 2013).…”

Section: Solubility In the Presence Of Hydratesmentioning

confidence: 99%

Xenon Hydrate as an Analog of Methane Hydrate in Geologic Systems Out of Thermodynamic Equilibrium

Waite

Cueto‐Felgueroso

et al. 2019

Geochem Geophys Geosyst

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Methane hydrate occurs naturally under pressure and temperature conditions that are not straightforward to replicate experimentally. Xenon has emerged as an attractive laboratory alternative to methane for studying hydrate formation and dissociation in multiphase systems, given that it forms hydrates under milder conditions. However, building reliable analogies between the two hydrates requires systematic comparisons, which are currently lacking. We address this gap by developing a theoretical and computational model of gas hydrates under equilibrium and nonequilibrium conditions. We first compare equilibrium phase behaviors of the Xe·H2O and CH4·H2O systems by calculating their isobaric phase diagram, and then study the nonequilibrium kinetics of interfacial hydrate growth using a phase field model. Our results show that Xe·H2O is a good experimental analog to CH4·H2O, but there are key differences to consider. In particular, the aqueous solubility of xenon is altered by the presence of hydrate, similar to what is observed for methane; but xenon is consistently less soluble than methane. Xenon hydrate has a wider nonstoichiometry region, which could lead to a thicker hydrate layer at the gas‐liquid interface when grown under similar kinetic forcing conditions. For both systems, our numerical calculations reveal that hydrate nonstoichiometry coupled with hydrate formation dynamics leads to a compositional gradient across the hydrate layer, where the stoichiometric ratio increases from the gas‐facing side to the liquid‐facing side. Our analysis suggests that accurate composition measurements could be used to infer the kinetic history of hydrate formation in natural settings where gas is abundant.

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Natural Gas Hydrates—Energy Resource Potential and Associated Geologic Hazards

Cited by 110 publications

References 0 publications

Structure II gas hydrates found below the bottom‐simulating reflector

Structure II gas hydrates found below the bottom‐simulating reflector

Methane hydrate induced permeability modification for multiphase flow in unsaturated porous media

Xenon Hydrate as an Analog of Methane Hydrate in Geologic Systems Out of Thermodynamic Equilibrium

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