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Special Issue "Natural Gas Hydrate 2013"

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A special issue of Energies (ISSN 1996-1073).

Deadline for manuscript submissions: closed (31 March 2013)

Special Issue Editor

Guest Editor
Prof. Richard B. Coffin (Website)

Department of Physical and Environmental Sciences, Texas A&M University - Corpus Christi, 6300 Ocean Drive, Corpus Christi, TX 78421, USA
Interests: variation in methane hydrate abundance in world ocean coastal regions; shallow sediment methane cycling; methane flux to the atmosphere; elemental isotope analyses

Special Issue Information

Dear Colleagues,

Gas hydrates are recognized an opportunity for new energy, a contribution to climate change, a significant factor in coastal stability and a potential approach to reduce carbon dioxide emissions. State of the art field and laboratory research requires integration of geophysics, geology, biology and geochemistry in field and laboratory to assess sediment methane hydrate loadings, predict carbon dioxide and methane hydrate stability, understand the hydrate role in ocean cycles, global economy, and reducing greenhouse gas emissions. Over the past years publications in this special issue have presented science on key issues lead by world leaders in gas hydrate research. This special issue invites papers on methane hydrate exploration and methane - carbon dioxide hydrate exchange related to alternate energy, carbon sequestration and climate change.

Dr. Richard B. Coffin
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed Open Access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs).

Published Papers (7 papers)

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Research

Open AccessArticle Sensitivity Analysis of Parameters Governing the Recovery of Methane from Natural Gas Hydrate Reservoirs
Energies 2014, 7(4), 2148-2176; doi:10.3390/en7042148
Received: 27 November 2013 / Revised: 3 March 2014 / Accepted: 13 March 2014 / Published: 1 April 2014
Cited by 1 | PDF Full-text (2528 KB) | HTML Full-text | XML Full-text
Abstract
Naturally occurring gas hydrates are regarded as an important future source of energy and considerable efforts are currently being invested to develop methods for an economically viable recovery of this resource. The recovery of natural gas from gas hydrate deposits has been [...] Read more.
Naturally occurring gas hydrates are regarded as an important future source of energy and considerable efforts are currently being invested to develop methods for an economically viable recovery of this resource. The recovery of natural gas from gas hydrate deposits has been studied by a number of researchers. Depressurization of the reservoir is seen as a favorable method because of its relatively low energy requirements. While lowering the pressure in the production well seems to be a straight forward approach to destabilize methane hydrates, the intrinsic kinetics of CH4-hydrate decomposition and fluid flow lead to complex processes of mass and heat transfer within the deposit. In order to develop a better understanding of the processes and conditions governing the production of methane from methane hydrates it is necessary to study the sensitivity of gas production to the effects of factors such as pressure, temperature, thermal conductivity, permeability, porosity on methane recovery from naturally occurring gas hydrates. A simplified model is the base for an ensemble of reservoir simulations to study which parameters govern productivity and how these factors might interact. Full article
(This article belongs to the Special Issue Natural Gas Hydrate 2013)
Open AccessArticle Formation and Dissociation of Methane Hydrates from Seawater in Consolidated Sand: Mimicking Methane Hydrate Dynamics beneath the Seafloor
Energies 2013, 6(12), 6225-6241; doi:10.3390/en6126225
Received: 5 September 2013 / Revised: 15 November 2013 / Accepted: 18 November 2013 / Published: 28 November 2013
Cited by 2 | PDF Full-text (8238 KB) | HTML Full-text | XML Full-text
Abstract
Methane hydrate formation and dissociation kinetics were investigated in seawater-saturated consolidated Ottawa sand-pack under sub-seafloor conditions to study the influence of effective pressure on formation and dissociation kinetics. To simulate a sub-seafloor environment, the pore-pressure was varied relative to confining pressure in [...] Read more.
Methane hydrate formation and dissociation kinetics were investigated in seawater-saturated consolidated Ottawa sand-pack under sub-seafloor conditions to study the influence of effective pressure on formation and dissociation kinetics. To simulate a sub-seafloor environment, the pore-pressure was varied relative to confining pressure in successive experiments. Hydrate formation was achieved by methane charging followed by sediment cooling. The formation of hydrates was delayed with increasing degree of consolidation. Hydrate dissociation by step-wise depressurization was instantaneous, emanating preferentially from the interior of the sand-pack. Pressure drops during dissociation and in situ temperature controlled the degree of endothermic cooling within sediments. In a closed system, the post-depressurization dissociation was succeeded by thermally induced dissociation and pressure-temperature conditions followed theoretical methane-seawater equilibrium conditions and exhibited excess pore pressure governed by the pore diameter. These post-depressurization equilibrium values for the methane hydrates in seawater saturated consolidated sand-pack were used to estimate the enthalpy of dissociation of 55.83 ± 1.41 kJ/mol. These values were found to be lower than those reported in earlier literature for bulk hydrates from seawater (58.84 kJ/mol) and pure water (62.61 kJ/mol) due to excess pore pressure generated within confined sediment system under investigation. However, these observations could be significant in the case of hydrate dissociation in a subseafloor environment where dissociation due to depressurization could result in an instantaneous methane release followed by slow thermally induced dissociation. The excess pore pressure generated during hydrate dissociation could be higher within fine-grained sediments with faults and barriers present in subseafloor settings which could cause shifting in geological layers. Full article
(This article belongs to the Special Issue Natural Gas Hydrate 2013)
Open AccessArticle Methane Gas Hydrate Stability Models on Continental Shelves in Response to Glacio-Eustatic Sea Level Variations: Examples from Canadian Oceanic Margins
Energies 2013, 6(11), 5775-5806; doi:10.3390/en6115775
Received: 29 August 2013 / Revised: 16 October 2013 / Accepted: 30 October 2013 / Published: 6 November 2013
Cited by 1 | PDF Full-text (4400 KB) | HTML Full-text | XML Full-text
Abstract
We model numerically regions of the Canadian continental shelves during successive glacio-eustatic cycles to illustrate past, current and future marine gas hydrate (GH) stability and instability. These models indicated that the marine GH resource has dynamic features and the formation age and [...] Read more.
We model numerically regions of the Canadian continental shelves during successive glacio-eustatic cycles to illustrate past, current and future marine gas hydrate (GH) stability and instability. These models indicated that the marine GH resource has dynamic features and the formation age and resource volumes depend on the dynamics of the ocean-atmosphere system as it responds to both natural (glacial-interglacial) and anthropogenic (climate change) forcing. Our models focus on the interval beginning three million years ago (i.e., Late Pliocene-Holocene). They continue through the current interglacial and they are projected to its anticipated natural end. During the current interglacial the gas hydrate stability zone (GHSZ) thickness in each region responded uniquely as a function of changes in water depth and sea bottom temperature influenced by ocean currents. In general, the GHSZ in the deeper parts of the Pacific and Atlantic margins (≥1316 m) thinned primarily due to increased water bottom temperatures. The GHSZ is highly variable in the shallower settings on the same margins (~400–500 m). On the Pacific Margin shallow GH dissociated completely prior to nine thousand years ago but the effects of subsequent sea level rise reestablished a persistent, thin GHSZ. On the Atlantic Margin Scotian Shelf the warm Gulf Stream caused GHSZ to disappear completely, whereas in shallow water depths offshore Labrador the combination of the cool Labrador Current and sea level rise increased the GHSZ. If future ocean bottom temperatures remain constant, these general characteristics will persist until the current interglacial ends. If the sea bottom warms, possibly in response to global climate change, there could be a significant reduction to complete loss of GH stability, especially on the shallow parts of the continental shelf. The interglacial GH thinning rates constrain rates at which carbon can be transferred between the GH reservoir and the atmosphere-ocean system. Marine GH can destabilize much more quickly than sub-permafrost terrestrial GHs and this combined with the immense marine GH reservoir suggests that GH have the potential to affect the climate-ocean system. Our models show that GH stability reacts quickly to water column pressure effects but slowly to sea bottom temperature changes. Therefore it is likely that marine GH destabilization was rapid and progressive in response to the pressure effects of glacial eustatic sea level fall. This suggests against a catastrophic GH auto-cyclic control on glacial-interglacial climate intervals. It is computationally possible but, unfortunately in no way verifiably, to analyze the interactions and impacts that marine GHs had prior to the current interglacial because of uncertainties in temperature and pressure history constraints. Thus we have the capability, but no confidence that we can contribute currently to questions regarding the relationships among climate, glacio-eustatic sea level fluctuations and marine GH stability without improved local temperature and water column histories. We infer that the possibility for a GH control on climate or oceanic cycles is speculative, but qualitatively contrary to our model results. Full article
(This article belongs to the Special Issue Natural Gas Hydrate 2013)
Open AccessArticle Evolution of Hydrate Dissociation by Warm Brine Stimulation Combined Depressurization in the South China Sea
Energies 2013, 6(10), 5402-5425; doi:10.3390/en6105402
Received: 25 August 2013 / Revised: 9 October 2013 / Accepted: 11 October 2013 / Published: 21 October 2013
Cited by 10 | PDF Full-text (1587 KB) | HTML Full-text | XML Full-text
Abstract
To evaluate the gas production performance of the hydrate accumulations in the South China Sea, a numerical simulation with warm brine stimulation combined depressurization has been conducted. A dual horizontal well system is considered as the well configuration in this work. In [...] Read more.
To evaluate the gas production performance of the hydrate accumulations in the South China Sea, a numerical simulation with warm brine stimulation combined depressurization has been conducted. A dual horizontal well system is considered as the well configuration in this work. In order to reduce energy input and improve energy utilization, warm brine (<30 °C) instead of hot brine (>50 °C) is injected into the reservoir for hydrate dissociation. The effect of the intrinsic permeability of the hydrate reservoir, the salinity and the temperature of the injected brine to gas hydrate exploitation have been investigated. The numerical simulation results indicate that the average gas production rate Qavg is about 1.23 ´ 105 ST m3/day for the entire hydrate deposit, which has the same order of magnitude compared with the commercially viable production rate. The injected brine can be pumped out from the upper production well directly after the hydrate between the two wells is dissociated completely. Thus, the effective region of heat and inhibitor stimulation is limited. The sensitivity analyses indicate that the dissociation rate of hydrate can be enhanced by increasing the temperature of the injected brine and raising the salinity of the injected brine. The parametric study of permeability shows that the hydrate of the reservoir with the larger permeability has a higher dissociation rate. Full article
(This article belongs to the Special Issue Natural Gas Hydrate 2013)
Open AccessArticle Effects of Impermeable Boundaries on Gas Production from Hydrate Accumulations in the Shenhu Area of the South China Sea
Energies 2013, 6(8), 4078-4096; doi:10.3390/en6084078
Received: 6 May 2013 / Revised: 2 July 2013 / Accepted: 15 July 2013 / Published: 8 August 2013
Cited by 2 | PDF Full-text (1748 KB) | HTML Full-text | XML Full-text
Abstract
Based on currently available data from site measurements and the preliminary estimates of the gas production potential from the hydrate accumulations at the SH7 site in the Shenhu Area using the depressurization method with a single horizontal well placed in the middle [...] Read more.
Based on currently available data from site measurements and the preliminary estimates of the gas production potential from the hydrate accumulations at the SH7 site in the Shenhu Area using the depressurization method with a single horizontal well placed in the middle of the Hydrate-Bearing Layer (HBL), the dependence of production performance on the permeabilities of the overburden (OB) and underburden (UB) layers was investigated in this modeling study. The simulation results indicated that the temperature and the pressure of the HBL were affected by the permeabilities of OB and UB and the effect of depressurization with impermeable OB and UB was significantly stronger than that with permeable boundaries. Considering the percentage of hydrate dissociation, the gas production rate and the gas-to-water ratio, the hydrate deposit with impermeable OB and UB was expected to be the potential gas production target. Full article
(This article belongs to the Special Issue Natural Gas Hydrate 2013)
Open AccessArticle Similarity Analysis in Scaling a Gas Hydrates Reservoir
Energies 2013, 6(5), 2468-2480; doi:10.3390/en6052468
Received: 19 March 2013 / Revised: 27 April 2013 / Accepted: 6 May 2013 / Published: 13 May 2013
Cited by 2 | PDF Full-text (349 KB) | HTML Full-text | XML Full-text
Abstract
A complete set of scaling criteria for gas hydrate reservoir of five-spot well system case is derived from the 3D governing equations, involving the mass balance equation, the energy balance equation, the kinetic model, the endothermic model and the phase equilibrium model. [...] Read more.
A complete set of scaling criteria for gas hydrate reservoir of five-spot well system case is derived from the 3D governing equations, involving the mass balance equation, the energy balance equation, the kinetic model, the endothermic model and the phase equilibrium model. In the scaling criteria, the key parameters of the experiment are the water/gas production rates, the water injection rate, and the production time. By using the scaling criteria, the experimental results can be enlarged to a field scale. Therefore, the experimental results and the scaling criteria could be used to evaluate the hydrate dissociation strategies and the gas production potential of the hydrate reservoir. Full article
(This article belongs to the Special Issue Natural Gas Hydrate 2013)
Open AccessArticle Hydrate Formation/Dissociation in (Natural Gas + Water + Diesel Oil) Emulsion Systems
Energies 2013, 6(2), 1009-1022; doi:10.3390/en6021009
Received: 11 December 2012 / Revised: 19 January 2013 / Accepted: 1 February 2013 / Published: 18 February 2013
Cited by 6 | PDF Full-text (214 KB) | HTML Full-text | XML Full-text
Abstract
Hydrate formation/dissociation of natural gas in (diesel oil + water) emulsion systems containing 3 wt% anti-agglomerant were performed for five water cuts: 5, 10, 15, 20, and 25 vol%. The natural gas solubilities in the emulsion systems were also examined. The experimental [...] Read more.
Hydrate formation/dissociation of natural gas in (diesel oil + water) emulsion systems containing 3 wt% anti-agglomerant were performed for five water cuts: 5, 10, 15, 20, and 25 vol%. The natural gas solubilities in the emulsion systems were also examined. The experimental results showed that the solubility of natural gas in emulsion systems increases almost linearly with the increase of pressure, and decreases with the increase of water cut. There exists an initial slow hydrate formation stage for systems with lower water cut, while rapid hydrate formation takes place and the process of the gas-liquid dissolution equilibrium at higher water cut does not appear in the pressure curve. The gas consumption amount due to hydrate formation at high water cut is significantly higher than that at low water cut. Fractional distillation for natural gas components also exists during the hydrate formation process. The experiments on hydrate dissociation showed that the dissociation rate and the amount of dissociated gas increase with the increase of water cut. The variations of temperature in the process of natural gas hydrate formation and dissociation in emulsion systems were also examined. Full article
(This article belongs to the Special Issue Natural Gas Hydrate 2013)

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