Special Issue "Advances in Natural Gas Hydrates"

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "Geo-Energy".

Deadline for manuscript submissions: 31 January 2020.

Special Issue Editor

Guest Editor
Assoc. Prof. Nicolas von Solms Website E-Mail
Department of Chemical and Biochemical Engineering, Technical University of Denmark, Lyngby, Denmark
Phone: +45 45 25 28 67
Interests: gas hydrates; thermodynamics and phase equilibrium; statistical mechanics; CO2 capture

Special Issue Information

Dear Colleagues,

For this Special Issue we solicit contributions in the area “Advances in Natural Gas Hydrates”. Subtopics of interest could include: the production of natural gas hydrate, gas hydrates for greenhouse gas mitigation, hydrates as separation agents, gas hydrates as gas transport agents, and hydrate inhibition in oil and gas production. In particular, quantitative engineering studies are sought: for example, thermodynamics and phase equilibrium of gas hydrate systems, kinetics of gas hydrate processes, and molecular simulation of gas hydrate processes and systems.

Prof. Nicolas von Solms
Guest Editor

Manuscript Submission Information

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. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short 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 thoroughly refereed through a single-blind 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 semimonthly 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 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • natural gas hydrates
  • methane hydrates
  • energy
  • carbon capture
  • thermodynamics
  • climate change
  • gas transport
  • hydrate inhibition

Published Papers (9 papers)

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Research

Open AccessArticle
Thermal State of the Blake Ridge Gas Hydrate Stability Zone (GHSZ)—Insights on Gas Hydrate Dynamics from a New Multi-Phase Numerical Model
Energies 2019, 12(17), 3403; https://doi.org/10.3390/en12173403 - 03 Sep 2019
Abstract
Marine sediments of the Blake Ridge province exhibit clearly defined geophysical indications for the presence of gas hydrates and a free gas phase. Despite being one of the world’s best-studied gas hydrate provinces and having been drilled during Ocean Drilling Program (ODP) Leg [...] Read more.
Marine sediments of the Blake Ridge province exhibit clearly defined geophysical indications for the presence of gas hydrates and a free gas phase. Despite being one of the world’s best-studied gas hydrate provinces and having been drilled during Ocean Drilling Program (ODP) Leg 164, discrepancies between previous model predictions and reported chemical profiles as well as hydrate concentrations result in uncertainty regarding methane sources and a possible co-existence between hydrates and free gas near the base of the gas hydrate stability zone (GHSZ). Here, by using a new multi-phase finite element (FE) numerical model, we investigate different scenarios of gas hydrate formation from both single and mixed methane sources (in-situ biogenic formation and a deep methane flux). Moreover, we explore the evolution of the GHSZ base for the past 10 Myr using reconstructed sedimentation rates and non-steady-state P-T solutions. We conclude that (1) the present-day base of the GHSZ predicted by our model is located at the depth of ~450 mbsf, thereby resolving a previously reported inconsistency between the location of the BSR at ODP Site 997 and the theoretical base of the GHSZ in the Blake Ridge region, (2) a single in-situ methane source results in a good fit between the simulated and measured geochemical profiles including the anaerobic oxidation of methane (AOM) zone, and (3) previously suggested 4 vol.%–7 vol.% gas hydrate concentrations would require a deep methane flux of ~170 mM (corresponds to the mass of methane flux of 1.6 × 10−11 kg s−1 m−2) in addition to methane generated in-situ by organic carbon (POC) degradation at the cost of deteriorating the fit between observed and modelled geochemical profiles. Full article
(This article belongs to the Special Issue Advances in Natural Gas Hydrates)
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Open AccessArticle
Magnetic Resonance Imaging of Methane Hydrate Formation and Dissociation in Sandstone with Dual Water Saturation
Energies 2019, 12(17), 3231; https://doi.org/10.3390/en12173231 - 22 Aug 2019
Abstract
This paper reports formation and dissociation patterns of methane hydrate in sandstone. Magnetic resonance imaging spatially resolved hydrate growth patterns and liberation of water during dissociation. A stacked core set-up using Bentheim sandstone with dual water saturation was designed to investigate the effect [...] Read more.
This paper reports formation and dissociation patterns of methane hydrate in sandstone. Magnetic resonance imaging spatially resolved hydrate growth patterns and liberation of water during dissociation. A stacked core set-up using Bentheim sandstone with dual water saturation was designed to investigate the effect of initial water saturation on hydrate phase transitions. The growth of methane hydrate (P = 8.3 MPa, T = 1–3 °C) was more prominent in high water saturation regions and resulted in a heterogeneous hydrate saturation controlled by the initial water distribution. The change in transverse relaxation time constant, T2, was spatially mapped during growth and showed different response depending on the initial water saturation. T2 decreased significantly during growth in high water saturation regions and remained unchanged during growth in low water saturation regions. Pressure depletion from one end of the core induced a hydrate dissociation front starting at the depletion side and moving through the core as production continued. The final saturation of water after hydrate dissociation was more uniform than the initial water saturation, demonstrating the significant redistribution of water that will take place during methane gas production from a hydrate reservoir. Full article
(This article belongs to the Special Issue Advances in Natural Gas Hydrates)
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Open AccessArticle
High-Pressure and Automatized System for Study of Natural Gas Hydrates
Energies 2019, 12(16), 3064; https://doi.org/10.3390/en12163064 - 09 Aug 2019
Abstract
Due to the declining of oil reserves in the world in the coming decades, gas hydrate (GH) is seen as the great promise to supply the planet’s energy demand. With this, the importance of studying the behavior of GH, several researchers have been [...] Read more.
Due to the declining of oil reserves in the world in the coming decades, gas hydrate (GH) is seen as the great promise to supply the planet’s energy demand. With this, the importance of studying the behavior of GH, several researchers have been developing different systems that allow greater truthfulness in relation to the conditions where GH is found in nature. This work describes a new system to simulate formation (precipitation) and dissociation of GH primarily at natural conditions at deep-sea, lakes, and permafrost, but also applied for artificial gas hydrates studies (pipelines, and transport of hydrocarbons, CO2, and hydrogen). This system is fully automated and unique, allowing the simultaneous work in two independent reactors, built in Hastelloy C-22, with a capacity of 1 L and 10 L, facilitating rapid analyses when compared to higher-volume systems. The system can operate using different mixtures of gases (methane, ethane, propane, carbon dioxide, nitrogen, ammonia), high pressure (up to 200 bar) with high operating safety, temperature (−30 to 200 °C), pH controllers, stirring system, water and gas samplers, and hyphenated system with gas chromatograph (GC) to analyze the composition of the gases formed in the GH and was projected to possibility the visualizations of experiments (quartz windows). Full article
(This article belongs to the Special Issue Advances in Natural Gas Hydrates)
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Open AccessArticle
Dilation Behavior of Gas-Saturated Methane-Hydrate Bearing Sand
Energies 2019, 12(15), 2937; https://doi.org/10.3390/en12152937 - 31 Jul 2019
Abstract
The geotechnical properties of methane-hydrate-bearing sediments (MHBS) are commonly investigated in the laboratory by using artificial hydrate formations in sandy specimens. Analyses of MHBS saturated with gas or water (in addition to methane-hydrate) showed significant mechanical differences between the two pore-filling states. This [...] Read more.
The geotechnical properties of methane-hydrate-bearing sediments (MHBS) are commonly investigated in the laboratory by using artificial hydrate formations in sandy specimens. Analyses of MHBS saturated with gas or water (in addition to methane-hydrate) showed significant mechanical differences between the two pore-filling states. This paper discusses the unique dilatancy behavior of gas-saturated MHBS, with comparison to water-saturated test results of previously-published works. It is shown that the significant compaction of gas-saturated samples is related to internal tensile forces, which are absent in water-saturated samples. The conceptual link between the internal tensile forces and the compaction characteristics is demonstrated through mechanical differences between pure sand and cemented sand. The paper establishes the link between internal adhesion in gas-saturated MHBS and the unique dilation response by using a stress–dilatancy analysis. Full article
(This article belongs to the Special Issue Advances in Natural Gas Hydrates)
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Open AccessArticle
A 3-In-1 Approach to Evaluate Gas Hydrate Inhibitors
Energies 2019, 12(15), 2921; https://doi.org/10.3390/en12152921 - 29 Jul 2019
Abstract
With a single apparatus and very short experimentation times, we have assessed phase equilibria, apparent kinetics and morphology of methane gas hydrates in the presence of thermodynamic inhibitors ethane-1,2-diol (MEG) and sodium chloride (NaCl); and kinetic hydrate inhibitor polyvinyl-pyrrolidone (PVP). Tight, local temperature [...] Read more.
With a single apparatus and very short experimentation times, we have assessed phase equilibria, apparent kinetics and morphology of methane gas hydrates in the presence of thermodynamic inhibitors ethane-1,2-diol (MEG) and sodium chloride (NaCl); and kinetic hydrate inhibitor polyvinyl-pyrrolidone (PVP). Tight, local temperature control produced highly repeatable crystal morphologies in constant temperature systems and in systems subject to fixed temperature gradients. Hydrate-Liquid-Vapor (HLV) equilibrium points were obtained with minimal temperature and pressure uncertainties (u T avg = 0.13 K and u p = 0.005 MPa). By applying a temperature gradient during hydrate formation, it was possible to study multiple subcoolings with a single experiment. Hydrate growth velocities were determined both under temperature gradients and under constant temperature growth. It was found that both NaCl and MEG act as kinetic inhibitors at the studied concentrations. Finally, insights on the mechanism of action of classical inhibitors are presented. Full article
(This article belongs to the Special Issue Advances in Natural Gas Hydrates)
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Open AccessArticle
Hydrate Stability and Methane Recovery from Gas Hydrate through CH4–CO2 Replacement in Different Mass Transfer Scenarios
Energies 2019, 12(12), 2309; https://doi.org/10.3390/en12122309 - 17 Jun 2019
Abstract
CH4–CO2 replacement is a carbon-negative, safer gas production technique to produce methane gas from natural gas hydrate reservoirs by injecting pure CO2 or other gas mixtures containing CO2. Laboratory-scale experiments show that this technique produces low methane [...] Read more.
CH4–CO2 replacement is a carbon-negative, safer gas production technique to produce methane gas from natural gas hydrate reservoirs by injecting pure CO2 or other gas mixtures containing CO2. Laboratory-scale experiments show that this technique produces low methane volume and has a slow replacement rate due to the mass transfer barrier created due to impermeable CO2 hydrate layer formation, thus making the process commercially unattractive. This mass-transfer barrier can be reduced through pressure reduction techniques and chemical techniques; however, very few studies have focused on depressurization-assisted and chemical-assisted CH4–CO2 replacement to lower mass-transfer barriers and there are many unknowns. In this work, we qualitatively and quantitatively investigated the effect of the pressure reduction and presence of a hydrate promoter on mixed hydrate stability, CH4 recovery, and risk of water production during CH4–CO2 exchange. Exchange experiments were carried out using the 500 ppm sodium dodecyl sulfate (SDS) solution inside a high-pressure stirred reactor. Our results indicated that mixed hydrate stability and methane recovery depends on the degree of pressure reduction, type, and composition of injected gas. Final selection between CO2 and CO2 + N2 gas depends on the tradeoff between mixed hydrate stability pressure and methane recovery. Hydrate morphology studies suggest that production of water during the CH4–CO2 exchange is a stochastic phenomenon that is dependent on many parameters. Full article
(This article belongs to the Special Issue Advances in Natural Gas Hydrates)
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Open AccessArticle
Thermo-Hydro-Mechanical Coupled Modeling of Methane Hydrate-Bearing Sediments: Formulation and Application
Energies 2019, 12(11), 2178; https://doi.org/10.3390/en12112178 - 07 Jun 2019
Cited by 2
Abstract
We present a fully coupled thermo-hydro-mechanical formulation for the simulation of sediment deformation, fluid and heat transport and fluid/solid phase transformations occurring in methane hydrate geological systems. We reformulate the governing equations of energy and mass balance of the Code_Bright simulator to incorporate [...] Read more.
We present a fully coupled thermo-hydro-mechanical formulation for the simulation of sediment deformation, fluid and heat transport and fluid/solid phase transformations occurring in methane hydrate geological systems. We reformulate the governing equations of energy and mass balance of the Code_Bright simulator to incorporate hydrate as a new pore phase. The formulation also integrates the constitutive model Hydrate-CASM to capture the effect of hydrate saturation in the mechanical response of the sediment. The thermo-hydraulic capabilities of the formulation are validated against the results from a series of state-of-the-art simulators involved in the first international gas hydrate code comparison study developed by the NETL-USGS. The coupling with the mechanical formulation is investigated by modeling synthetic dissociation tests and validated by reproducing published experimental data from triaxial tests performed in hydrate-bearing sands dissociated via depressurization. Our results show that the formulation captures the dominant mass and heat transfer phenomena occurring during hydrate dissociation and reproduces the stress release and volumetric deformation associated with this process. They also show that the hydrate production method has a strong influence on sediment deformation. Full article
(This article belongs to the Special Issue Advances in Natural Gas Hydrates)
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Open AccessArticle
Micromechanical Investigation of Stress Relaxation in Gas Hydrate-Bearing Sediments Due to Sand Production
Energies 2019, 12(11), 2131; https://doi.org/10.3390/en12112131 - 04 Jun 2019
Abstract
Past experience of gas production from methane-hydrate-bearing sediments indicates that sand migration is a major factor restricting the production of gas from methane-hydrate reservoirs. One important geotechnical aspect of sand migration is the influence of grain detachment on the existing stresses. This paper [...] Read more.
Past experience of gas production from methane-hydrate-bearing sediments indicates that sand migration is a major factor restricting the production of gas from methane-hydrate reservoirs. One important geotechnical aspect of sand migration is the influence of grain detachment on the existing stresses. This paper focuses on understanding and quantifying the nature of this aspect using different approaches, with a focus on discrete element method (DEM) simulations of sand detachment from hydrate-bearing sand samples. The investigation in the paper reveals that sand migration affects isotropic and deviatoric stresses differently. In addition, the existence of hydrate moderates the magnitude of stress relaxation. Both of these features are currently missing from continuum-based models, and therefore, a new constitutive model for stress relaxation is suggested, incorporating the research findings. Model parameters are suggested based on the DEM simulations. The model is suitable for continuum mechanics-based simulations of gas production from hydrate reservoirs. Full article
(This article belongs to the Special Issue Advances in Natural Gas Hydrates)
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Open AccessArticle
The Study of Flow Characteristics During the Decomposition Process in Hydrate-Bearing Porous Media Using Magnetic Resonance Imaging
Energies 2019, 12(9), 1736; https://doi.org/10.3390/en12091736 - 08 May 2019
Abstract
The flow characteristics during decomposition of hydrate-bearing sediments are the most critical parameters for the gas recovery potential from natural gas hydrate reservoirs. The absolute and relative permeability and the flow field distribution during the decomposition process of hydrate-bearing porous media synthetically created [...] Read more.
The flow characteristics during decomposition of hydrate-bearing sediments are the most critical parameters for the gas recovery potential from natural gas hydrate reservoirs. The absolute and relative permeability and the flow field distribution during the decomposition process of hydrate-bearing porous media synthetically created by glass beads are in-situ measured by using magnetic resonance imaging. The absolute permeability value increased slowly, then became stable after the decomposition amount was 50%. The relative permeability change curve is a typical X-shaped cross curve. As the hydrate decomposed, the relative permeability values of the two phases increased, the range of the two-phase co-infiltration zone increased with the increase of relative permeability at the endpoint, and the coexistence water saturation decreased. At the beginning of the decomposition, (hydrate content 100% to 70%), the relative permeability of methane and water rose rapidly from 22% to 51% and from 58% to 70%, respectively. When the amount of the remaining hydrate was less than 50%, the relative permeability curve of the hydrate-bearing glass beads almost kept unchanged. During the hydrate decomposition process, the velocity distribution was very uneven and coincided with the porous media structure. Full article
(This article belongs to the Special Issue Advances in Natural Gas Hydrates)
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