SS - Gas Hydrate : Study for the Estimation of Seabed Stratum Deformation in Methane Hydrate Production

2010 ◽  
Author(s):  
Eiji Ogisako ◽  
Shinya Nishio ◽  
Atsushi Denda ◽  
Fusao Oka ◽  
Sayuri Kimoto
Keyword(s):  
Gas Hydrate ◽  
Methane Hydrate ◽  
Stratum Deformation

SS - Gas Hydrate: Gas production from methane hydrate sediment layer by thermal stimulation with hot water injection

2010 ◽  
Author(s):  
Kyuro Sasaki ◽  
Shinzi Ono ◽  
Yuichi Sugai ◽  
Norio Tenma ◽  
Takao Ebinuma ◽  
...  
Keyword(s):  
Gas Hydrate ◽  
Methane Hydrate ◽  
Water Injection ◽  
Gas Production ◽  
Hot Water ◽  
Thermal Stimulation ◽  
Sediment Layer

Influence of a Combined Low Dosage Gas Hydrate Inhibitor on Methane Hydrate Surface

2014 ◽  
Vol 1008-1009 ◽  
pp. 300-306
Author(s):  
Cui Ping Tang ◽  
Dong Liang Li ◽  
De Qing Liang
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Gas Hydrate ◽  
Methane Hydrate ◽  
Md Simulation ◽  
Side Group ◽  
Large Space ◽  
Surface Molecules ◽  
Low Dosage

According to analysis of the gas hydrate cage and structure of the inhibitor and simulation of molecular dynamics, the interaction between GHI1 and hydrates was discussed. The structure analysis indicated the side group of PVP can insert into the open hydrate cage, and force the hydrate growing along the polymer chain, which results in a large space resistance and inhibits gas hydrate agglomerating. The results of MD simulation show GHI1 can damage the surface cage in hydrate lattice; the hydrogen and oxygen in GHI1 can form hydrogen bonds respectively with oxygen and hydrogen in hydrates, which makes the surface molecules of the cages unstable and distorts the cages; Synergist diethylene glycol ether increases strength and range of length of hydrogen bond.

scholarly journals Numerical Investigation into the Development Performance of Gas Hydrate by Depressurization Based on Heat Transfer and Entropy Generation Analyses

Entropy ◽  
2020 ◽  
Vol 22 (11) ◽  
pp. 1212 ◽  
Author(s):  
Bo Li ◽  
Wen-Na Wei ◽  
Qing-Cui Wan ◽  
Kang Peng ◽  
Ling-Ling Chen
Keyword(s):  
Heat Transfer ◽  
Energy Loss ◽  
Entropy Production ◽  
Entropy Generation ◽  
Gas Hydrate ◽  
Methane Hydrate ◽  
Dynamic Properties ◽  
Entropy Production Rate ◽  
Entropy Flow ◽  
Hydrate Reservoir

The purpose of this study is to analyze the dynamic properties of gas hydrate development from a large hydrate simulator through numerical simulation. A mathematical model of heat transfer and entropy production of methane hydrate dissociation by depressurization has been established, and the change behaviors of various heat flows and entropy generations have been evaluated. Simulation results show that most of the heat supplied from outside is assimilated by methane hydrate. The energy loss caused by the fluid production is insignificant in comparison to the heat assimilation of the hydrate reservoir. The entropy generation of gas hydrate can be considered as the entropy flow from the ambient environment to the hydrate particles, and it is favorable from the perspective of efficient hydrate exploitation. On the contrary, the undesirable entropy generations of water, gas and quartz sand are induced by the irreversible heat conduction and thermal convection under notable temperature gradient in the deposit. Although lower production pressure will lead to larger entropy production of the whole system, the irreversible energy loss is always extremely limited when compared with the amount of thermal energy utilized by methane hydrate. The production pressure should be set as low as possible for the purpose of enhancing exploitation efficiency, as the entropy production rate is not sensitive to the energy recovery rate under depressurization.

SS - Gas Hydrate: Microscale Modelling of Dissociation and Formation of Methane Hydrate in Sediment

2010 ◽  
Author(s):  
Ayako Fukumoto ◽  
Toru Sato ◽  
Shinichiro Hirabayashi ◽  
Paul Brumby ◽  
Fumio Kiyono ◽  
...  
Keyword(s):  
Gas Hydrate ◽  
Methane Hydrate ◽  
Microscale Modelling

Methane hydrate mobilization by ice stream erosion during the last glacial

2020 ◽  
Author(s):  
Pavel Serov ◽  
Henry Patton ◽  
Malin Waage ◽  
Calvin Shackleton ◽  
Jurgen Mienert ◽  
...  
Keyword(s):  
Gas Hydrate ◽  
Methane Hydrate ◽  
Barents Sea ◽  
Ice Sheet ◽  
Permafrost Degradation ◽  
Last Glacial ◽  
The Barents Sea ◽  
Ice Stream ◽  
Geophysical Imaging ◽  
The Last Glacial

<p>During the past ~2.6 Ma, some 30 glaciations have caused episodic high pressure and low temperature conditions and forced growth and decay of extensive subglacial methane hydrate accumulations globally. Research on Arctic methane release has primarily focused on warm, interglacial episodes when hydrates became unstable across territories either abandoned by former ice sheets or affected by permafrost degradation. Here we present a new mechanism – the subglacial erosion of gas hydrate-bearing sediments – that actively mobilizes methane in hydrate and dissolved form and delivers it to the ice sheet margin. We investigate this mechanism using geophysical imaging and ice sheet/gas hydrate modeling focused on a study site in Storfjordrenna, that hosted large ice stream draining the Barents Sea ice sheet. During the last glacial, we find that this ice stream overrode an extensive cluster of conduits that supplied a continuous methane flux from a deep, thermogenic source and delivered it to the subglacial environment. Our analysis reveals that 15,000 to 44,000 m<sup>3</sup> of gas hydrates were subglacially eroded from the 17 km<sup>2</sup> study site and transported to the shelf-edge. Given the abundance of natural gas reservoirs across the Barents Sea and marine-based glaciated petroleum provinces elsewhere, we propose that this mechanism had the potential to mobilize a substantial flux of subglacial methane throughout multiple Quaternary glacial episodes.</p>

MRI Visualization of Spontaneous Methane Production From Hydrates in Sandstone Core Plugs When Exposed to CO2

SPE Journal ◽  
2008 ◽  
Vol 13 (02) ◽  
pp. 146-152 ◽  
Author(s):  
Arne Graue ◽  
B. Kvamme ◽  
Bernie Baldwin ◽  
Jim Stevens ◽  
James J. Howard ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Hydrates ◽  
Gas Hydrate ◽  
Methane Production ◽  
Methane Hydrate ◽  
Co2 Storage ◽  
Natural Gas Hydrate ◽  
Hydrate Dissociation ◽  
Natural Gas Hydrates ◽  
The Stability

Summary Magnetic resonance imaging (MRI) of core samples in laboratory experiments showed that CO2 storage in gas hydrates formed in porous rock resulted in the spontaneous production of methane with no associated water production. The exposure of methane hydrate in the pores to liquid CO2 resulted in methane production from the hydrate that suggested the exchange of methane molecules with CO2 molecules within the hydrate without the addition or subtraction of significant amounts of heat. Thermodynamic simulations based on Phase Field Theory were in agreement with these results and predicted similar methane production rates that were observed in several experiments. MRI-based 3D visualizations of the formation of hydrates in the porous rock and the methane production improved the interpretation of the experiments. The sequestration of an important greenhouse gas while simultaneously producing the freed natural gas offers access to the significant amounts of energy bound in natural gas hydrates and also offers an attractive potential for CO2 storage. The potential danger associated with catastrophic dissociation of hydrate structures in nature and the corresponding collapse of geological formations is reduced because of the increased thermodynamic stability of the CO2 hydrate relative to the natural gas hydrate. Introduction The replacement of methane in natural gas hydrates with CO2 presents an attractive scenario of providing a source of abundant natural gas while establishing a thermodynamically more stable hydrate accumulation. Natural gas hydrates represent an enormous potential energy source as the total energy corresponding to natural gas entrapped in hydrate reservoirs is estimated to be more than twice the energy of all known energy sources of coal, oil, and gas (Sloan 2003). Thermodynamic stability of the hydrate is sensitive to local temperature and pressure, but all components in the hydrate have to be in equilibrium with the surroundings if the hydrate is to be thermodynamically stable. Natural gas hydrate accumulations are therefore rarely in a state of complete stability in a strict thermodynamic sense. Typically, the hydrate associated with fine-grain sediments is trapped between low-permeability layers that keep the system in a state of very slow dynamics. One concern of hydrate dissociation, especially near the surface of either submarine or permafrost-associated deposits, is the potential for the release of methane to the water column or atmosphere. Methane represents an environmental concern because it is a more aggressive (~25 times) greenhouse gas than CO2. A more serious concern is related to the stability of these hydrate formations and its impact on the surrounding sediments. Changes in local conditions of temperature, pressure, or surrounding fluids can change the dynamics of the system and lead to catastrophic dissociation of the hydrates and consequent sediment instability. The Storegga mudslide in offshore Norway was created by several catastrophic hydrate dissociations. The largest of these was estimated to have occurred 7,000 years ago and was believed to have created a massive tsunami (Dawson et al. 1988). The replacement of natural gas hydrate with CO2 hydrate has the potential to increase the stability of hydrate-saturated sediments under near-surface conditions. Hydrocarbon exploitation in hydrate-bearing regions has the additional challenge to drilling operations of controlling heat production from drilling and its potential risk of local hydrate dissociation (Yakushev and Collett 1992). The molar volume of hydrate is 25-30% greater than the volume of liquid water under the same temperature-pressure conditions. Any production scenario for natural gas hydrate that involves significant dissociation of the hydrate (e.g., pressure depletion) has to account for the release of significant amounts of water that in turn affects the local mechanical stress on the reservoir formation. In the worst case, this would lead to local collapse of the surrounding formation. Natural gas production by CO2 exchange and sequestration benefits from the observation that there is little or no associated liquid water production during this process. Production of gas by hydrate dissociation can produce large volumes of associated water, and can create a significant environmental problem that would severely limit the economic potential. The conversion from methane hydrate to a CO2 hydrate is thermodynamically favorable in terms of free energy differences, and the phase transition is coupled to corresponding processes of mass and heat transport. The essential question is then if it is possible to actually convert methane hydrate as found in sediments to CO2 hydrate. Experiments that formed natural gas hydrates in porous sandstone core plugs used MRI to monitor the dynamics of hydrate formation and reformation. The paper emphasizes the experimental procedures developed to form the initial natural gas hydrates in sandstone pores and the subsequent exchange with CO2 while monitoring the dynamic process with 3D imaging on a sub millimetre scale. The in-situ imaging illustrates the production of methane from methane hydrate when exposed to liquid CO2 without any external heating.

scholarly journals Experimental Study on the Shear Band of Methane Hydrate-Bearing Sediment

2021 ◽  
Vol 9 (11) ◽  
pp. 1158
Author(s):  
Xiaobing Lu ◽  
Xuhui Zhang ◽  
Fangfang Sun ◽  
Shuyun Wang ◽  
Lele Liu ◽  
...  
Keyword(s):  
Shear Band ◽  
Gas Hydrate ◽  
Methane Hydrate ◽  
Triaxial Compression ◽  
Shear Banding ◽  
Oblique Line ◽  
Shear Bands ◽  
Compression Tests ◽  
Computer Tomography Scan ◽  
Hydrate Saturation

The occurrence of a shear band is often thought as the precursor of failure. To study the initiation of shear banding in gas hydrate-bearing sediments, two groups of triaxial compression tests combined with a CT (computer tomography) scan were conducted by triaxial CT-integrated equipment under two confining pressures and seven hydrate saturations. The macro stress–strain curves and the corresponding CT scanning images of the micro-structure and the distribution of the components were obtained. The geometric parameters of the shear bands were measured based on the CT images at four typical axial strains, respectively. The distribution characteristics of soil particles, water, hydrate and gas were also analyzed. It is shown that the existence of methane hydrate changes the mechanical property of hydrate-bearing sediment from plastic failure to brittle failure when the hydrate saturation is over 13%, which occurs in the range of the tests in this paper. The peak of the deviatoric stress increases with the hydrate saturation. The shear band is in either a single oblique line or inter-cross lines depending on the hydrate saturation, the effective confining pressure and the initial distribution of the gas hydrate. Most of the shear band surfaces are not straight, and the widths of the shear bands are almost non-uniformly distributed.

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