http://www.mdpi.com/journal/energies/special_issues/methane-clathrate/ Dear Colleagues, Gas hydrates, recognized to be distributed through the world coastal oceans, are a significant energy source, have potential to influence coastal ocean platform stability, are an important component in climate change, and may contribute significantly to the overlying water column carbon cycles. Large investments for evaluation of methane hydrates as an energy source are ongoing at the Mackenzie Delta and Prudhoe Bay in the Arctic, the Nankai Trough off Japan, the Bay of Bengal near India, and on the Texas-Louisiana Shelf in the Gulf of Mexico. In addition to these large scale efforts, preliminary investigation of hydrate as a resource has started off on the coasts of New Zealand, Korea, Russia, Norway, Chile and other countries. Methane in hydrates is also being studied in Arctic coastal permafrost as a contribution to climate change. Addressing the development of this resource requires integration of a wide array of chemical, physical, geophysical and biological laboratory and field data. This special issue will combine papers on methods for evaluating deep sediment hydrate quantities, regional resource characterization, the methane contribution to shallow sediment and overlying water column carbon cycling, and predicted contributions to climate change. A primary goal is to share a thorough global overview of the current activity related to methane hydrate research. Richard B. Coffin, Ph. D. Prof. Dr. Ross Chapman Guest Editors {snippet name="submission_info"} http://www.mdpi.com/1996-1073/4/2/294/ Gas hydrates have been attracted a great deal of attention because of their potential as an energy substitute and the climate implications. Drilling and sampling research on the hydrate deposit in the Shenhu Area on the northern continental slope of the Southern China Sea was a big breakthrough for hydrate investigation in China, but as a new potential energy source, how the gas can be effectively produced from hydrate deposits has become a hot research topic. Besides depressurization heat stimulation is regarded as another important means for producing hydrate-derived gas, however, the production efficiency and economic feasibility of producing gas by heat stimulation have not been clearly understood. In this paper, a simplified model for predicting gas production from hydrate deposits by heat stimulation is developed. The model ideally neglects the effects of heat convection and pressure regime in the sediments for simplicity. We compute the heat consumption efficiency and gas energy efficiency of gas production from hydrate deposits by heat stimulation, only considering effect of hydrate dissociation due to heat input. This model is for predicting the maximum production efficiency. By studying the hydrate reservoirs and significant parameters collected from drilling and sampling researches, we calculate the production potential of the Shenhu hydrate deposits and investigate the production efficiency and feasibility. Our research shows that the maximum amount of cumulative gas production at Shenhu is ~509 m3 per meter in three years. The production potential is much lower than the industrial criterion for marine production. In our discussion the numerical simulations show that a practical potential of the gas production is merely 25 m3/m in 3 years and contribution of thermal stimulation is very small in joint-production schemes. We conclude that production cost is quite high and the economic value of producing gas from the hydrate through a vertical well is not attractive, even though the production by heat stimulation theoretically has a very high heat consumption rate and energy efficiency. http://www.mdpi.com/1996-1073/4/2/294/ Mon, 14 Feb 2011 00:00:00 CET Energies 2011-02-14 4 2 Article 294 313 1996-1073 Numerical Analysis on Gas Production Efficiency from Hydrate Deposits by Thermal Stimulation: Application to the Shenhu Area, South China Sea 2011-02-14 doi: 10.3390/en4020294 Zheng Su Yuncheng Cao Nengyou Wu Yong He http://www.mdpi.com/1996-1073/4/2/215/ Over the last decade global natural gas consumption has steadily increased since many industrialized countries are substituting natural gas for coal to generate electricity. There is also significant industrialization and economic growth of the heavily populated Asian countries of India and China. The general consensus is that there are vast quantities of natural gas trapped in hydrate deposits in geological systems, and this has resulted in the emerging importance of hydrates as a potential energy resource and an accompanying proliferation of recent studies on the technical and economic feasibility of gas production from hydrates. There are then the associated environmental concerns. This study reviews the state of knowledge with respect to natural gas hydrates and outlines remaining challenges and knowledge gaps. http://www.mdpi.com/1996-1073/4/2/215/ Tue, 25 Jan 2011 00:00:00 CET Energies 2011-01-25 4 2 Review 215 238 1996-1073 Towards Commercial Gas Production from Hydrate Deposits 2011-01-25 doi: 10.3390/en4020215 Jill Marcelle-De Silva Richard Dawe http://www.mdpi.com/1996-1073/4/1/151/ The presence of natural gas hydrates at all active and passive continental margins has been proven. Their global occurrence as well as the fact that huge amounts of methane and other lighter hydrocarbons are stored in natural gas hydrates has led to the idea of using hydrate bearing sediments as an energy resource. However, natural gas hydrates remain stable as long as they are in mechanical, thermal and chemical equilibrium with their environment. Thus, for the production of gas from hydrate bearing sediments, at least one of these equilibrium states must be disturbed by depressurization, heating or addition of chemicals such as CO2. Depressurization, thermal or chemical stimulation may be used alone or in combination, but the idea of producing hydrocarbons from hydrate bearing sediments by CO2 injection suggests the potential of an almost emission free use of this unconventional natural gas resource. However, up to now there are still open questions regarding all three production principles. Within the framework of the German national research project SUGAR the thermal stimulation method by use of in situ combustion was developed and tested on a pilot plant scale and the CH4-CO2 swapping process in gas hydrates studied on a molecular level. Microscopy, confocal Raman spectroscopy and X-ray diffraction were used for in situ investigations of the CO2-hydrocarbon exchange process in gas hydrates and its driving forces. For the thermal stimulation a heat exchange reactor was designed and tested for the exothermal catalytic oxidation of methane. Furthermore, a large scale reservoir simulator was realized to synthesize hydrates in sediments under conditions similar to nature and to test the efficiency of the reactor. Thermocouples placed in the reservoir simulator with a total volume of 425 L collect data regarding the propagation of the heat front. In addition, CH4 sensors are placed in the water saturated sediment to detect the distribution of CH4 in the sample. These data are used for numerical simulations for up-scaling from laboratory to field conditions. This study presents the experimental set up of the large scale reservoir simulator and the reactor design. Preliminary results indicate that the catalytic oxidation of CH4 operated as a temperature controlled, autothermal reaction in a countercurrent heat exchange reactor is a safe and promising tool for the thermal stimulation of hydrates. In addition, preliminary results from the laboratory studies on the CO2-hydrocarbon swapping process in simple and mixed gas hydrates are presented. http://www.mdpi.com/1996-1073/4/1/151/ Wed, 19 Jan 2011 00:00:00 CET Energies 2011-01-19 4 1 Article 151 172 1996-1073 New Approaches for the Production of Hydrocarbons from Hydrate Bearing Sediments 2011-01-19 doi: 10.3390/en4010151 Judith M. Schicks Erik Spangenberg Ronny Giese Bernd Steinhauer Jens Klump Manja Luzi http://www.mdpi.com/1996-1073/4/1/140/ Shale inhibition, low-temperature performance, the ability to prevent calcium and magnesium-ion pollution, and hydrate inhibition of polyethylene glycol drilling fluid were each tested with conventional drilling-fluid test equipment and an experimental gas-hydrate integrated simulation system developed by our laboratory. The results of these tests show that drilling fluid with a formulation of artificial seawater, 3% bentonite, 0.3% Na2CO3, 10% polyethylene glycol, 20% NaCl, 4% SMP-2, 1% LV-PAC, 0.5% NaOH and 1% PVP K-90 performs well in shale swelling and gas hydrate inhibition. It also shows satisfactory rheological properties and lubrication at temperature ranges from −8 °C to 15 °C. The PVP K-90, a kinetic hydrate inhibitor, can effectively inhibit gas hydrate aggregations at a dose of 1 wt%. This finding demonstrates that a drilling fluid with a high addition of NaCl and a low addition of PVP K-90 is suitable for drilling in natural marine gas-hydrate-bearing sediments. http://www.mdpi.com/1996-1073/4/1/140/ Wed, 19 Jan 2011 00:00:00 CET Energies 2011-01-19 4 1 Article 140 150 1996-1073 Polyethylene Glycol Drilling Fluid for Drilling in Marine Gas Hydrates-Bearing Sediments: An Experimental Study 2011-01-19 doi: 10.3390/en4010140 Guosheng Jiang Tianle Liu Fulong Ning Yunzhong Tu Ling Zhang Yibing Yu Lixin Kuang http://www.mdpi.com/1996-1073/4/1/39/ A gas hydrate reservoir, identified by the presence of the bottom simulating reflector, is located offshore of the Antarctic Peninsula. The analysis of geophysical dataset acquired during three geophysical cruises allowed us to characterize this reservoir. 2D velocity fields were obtained by using the output of the pre-stack depth migration iteratively. Gas hydrate amount was estimated by seismic velocity, using the modified Biot-Geerstma-Smit theory. The total volume of gas hydrate estimated, in an area of about 600 km2, is in a range of 16 × 109–20 × 109 m3. Assuming that 1 m3 of gas hydrate corresponds to 140 m3 of free gas in standard conditions, the reservoir could contain a total volume that ranges from 1.68 to 2.8 × 1012 m3 of free gas. The interpretation of the pre-stack depth migrated sections and the high resolution morpho-bathymetry image allowed us to define a structural model of the area. Two main fault systems, characterized by left transtensive and compressive movement, are recognized, which interact with a minor transtensive fault system. The regional geothermal gradient (about 37.5 °C/km), increasing close to a mud volcano likely due to fluid-upwelling, was estimated through the depth of the bottom simulating reflector by seismic data. http://www.mdpi.com/1996-1073/4/1/39/ Fri, 31 Dec 2010 00:00:00 CET Energies 2010-12-31 4 1 Article 39 56 1996-1073 Offshore Antarctic Peninsula Gas Hydrate Reservoir Characterization by Geophysical Data Analysis 2010-12-31 doi: 10.3390/en4010039 Maria Filomena Loreto Umberta Tinivella Flavio Accaino Michela Giustiniani http://www.mdpi.com/1996-1073/3/12/2001/ Gas hydrates have lately received increased attention as a potential future energy source, which is not surprising given their global and widespread occurrence. This article presents an integrated study of the Nyegga site offshore mid-Norway, where a gas hydrate prospect is defined on the basis of a multitude of geophysical models and one shallow geotechnical borehole. This prospect appears to hold around 625GSm3 (GSm3 = 109 standard cubic metres) of gas. The uncertainty related to the input parameters is dealt with through a stochastic calculation, giving a spread of in-place volumes of 183GSm3 (P90) to 1431GSm3 (P10). The resource density for Nyegga is found to be comparable to published resource assessments of other global hydrate provinces. http://www.mdpi.com/1996-1073/3/12/2001/ Wed, 22 Dec 2010 00:00:00 CET Energies 2010-12-22 3 12 Article 2001 2026 1996-1073 First-Order Estimation of In-Place Gas Resources at the Nyegga Gas Hydrate Prospect, Norwegian Sea 2010-12-22 doi: 10.3390/en3122001 Kim Senger Stefan Bünz Jürgen Mienert http://www.mdpi.com/1996-1073/3/12/1991/ The phase diagram for methane + water is explained, in relation to hydrate applications, such as in flow assurance and in nature. For natural applications, the phase diagram determines the regions for hydrate formation for two- and three-phase conditions. Impacts are presented for sample preparation and recovery. We discuss an international study for “Round Robin” hydrate sample preparation protocols and testing. http://www.mdpi.com/1996-1073/3/12/1991/ Tue, 21 Dec 2010 00:00:00 CET Energies 2010-12-21 3 12 Review 1991 2000 1996-1073 Gas Hydrate Stability and Sampling: The Future as Related to the Phase Diagram 2010-12-21 doi: 10.3390/en3121991 E. Dendy Sloan Carolyn A. Koh Amadeu K. Sum http://www.mdpi.com/1996-1073/3/12/1960/ Clathrate hydrates have recently received attention as novel storage and transportation materials for natural gases or hydrogen. These hydrates are treated as powders or particles, and moderate storage temperatures (around 253 K) are set for economic reasons. Thus, it is necessary to consider the sintering of hydrate particles for their easy handling because the hydrates have a framework similar to that of ice, even though their sintering would require guest molecules in addition to water molecules. We observed the sintering process of clathrate hydrates to estimate the rate of sintering. Spherical tetrahydrofuran (THF) hydrate particles were used in observations of sintering under a microscope equipped with a CCD camera and a time-lapse video recorder. We found that THF hydrate particles stored at temperatures below the equilibrium condition sintered like ice particles. The sintering part was confirmed to be not ice, but THF hydrate, by increasing the temperature above 273 K after each experiment. The sintering rate was lower than that of ice particles under the normal vapor condition at the same temperature. However, it became of the same order when the atmosphere of the sample was saturated with THF vapor. This indicates that the sintering rate of THF hydrate was controlled by the transportation of guest molecules through the vapor phase accompanied with water molecules. http://www.mdpi.com/1996-1073/3/12/1960/ Mon, 13 Dec 2010 00:00:00 CET Energies 2010-12-13 3 12 Article 1960 1971 1996-1073 Observation of Sintering of Clathrate Hydrates 2010-12-13 doi: 10.3390/en3121960 Tsutomu Uchida Toshiki Shiga Masafumi Nagayama Kazutoshi Gohara http://www.mdpi.com/1996-1073/3/12/1934/ In this review, the intriguing, anomalous behaviour of hydrate thermal conductivity will be described, and progress in performing experimental measurements will be described briefly. However particular attention shall be devoted to recent advances in the development of detailed theoretical understandings of mechanisms of thermal conduction in clathrate hydrates, and on how information gleaned from molecular simulation has contributed to mechanistic theoretical models. http://www.mdpi.com/1996-1073/3/12/1934/ Fri, 10 Dec 2010 00:00:00 CET Energies 2010-12-10 3 12 Review 1934 1942 1996-1073 Perspectives on Hydrate Thermal Conductivity 2010-12-10 doi: 10.3390/en3121934 Niall J. English John S. Tse http://www.mdpi.com/1996-1073/3/12/1861/ A method is proposed that uses renewable solar energy to supply energy for the exploitation of marine gas hydrates using thermal stimulation. The system includes solar cells, which are installed on the platform and a distributor with electric heaters. The solar module is connected with electric heaters via an insulated cable, and provides power to the heaters. Simplified equations are given for the calculation of the power of the electric heaters and the solar battery array. Also, a case study for the Shenhu area is provided to illustrate the calculation of the capacity of electric power and the solar cell system under ideal conditions. It is shown that the exploitation of marine gas hydrates by solar energy is technically and economically feasible in typical marine areas and hydrate reservoirs such as the Shenhu area. This method may also be used as a good assistance for depressurization exploitation of marine gas hydrates in the future. http://www.mdpi.com/1996-1073/3/12/1861/ Thu, 02 Dec 2010 00:00:00 CET Energies 2010-12-02 3 12 Article 1861 1879 1996-1073 A Method to Use Solar Energy for the Production of Gas from Marine Hydrate-Bearing Sediments: A Case Study on the Shenhu Area 2010-12-02 doi: 10.3390/en3121861 Fulong Ning Nengyou Wu Guosheng Jiang Ling Zhang Jin’an Guan Yibing Yu Fenglin Tang http://www.mdpi.com/1996-1073/3/6/1154/ Researchers at DOE’s National Energy Technology Laboratory (NETL) have been investigating the formation of synthetic gas hydrates, with an emphasis on rapid and continuous hydrate formation techniques. The investigations focused on unconventional methods to reduce dissolution, induction, nucleation and crystallization times associated with natural and synthetic hydrates studies conducted in the laboratory. Numerous experiments were conducted with various high-pressure cells equipped with instrumentation to study rapid and continuous hydrate formation. The cells ranged in size from 100 mL for screening studies to proof-of-concept studies with NETL’s 15-Liter Hydrate Cell. Results from this work demonstrate that the rapid and continuous formation of methane hydrate is possible at predetermined temperatures and pressures within the stability zone of a Methane Hydrate Stability Curve (see Figure 1). http://www.mdpi.com/1996-1073/3/6/1154/ Mon, 07 Jun 2010 00:00:00 CEST Energies 2010-06-07 3 6 Article 1154 1175 1996-1073 Rapid Gas Hydrate Formation Processes: Will They Work? 2010-06-07 doi: 10.3390/en3061154 Brown Taylor Bernardo