scholarly journals Effect of hydrate saturation on the shear bands of methane hydrate-bearing sediments based on the DEM simulation

2019 ◽  
Vol 376 ◽  
pp. 012048
Author(s):  
Hui Wang ◽  
Bo Zhou ◽  
Shifeng Xue
Keyword(s):  
Methane Hydrate ◽  
Shear Bands ◽  
Dem Simulation ◽  
Hydrate Saturation ◽  
Hydrate Bearing Sediments

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.

scholarly journals Effect of Permeability on Hydrate-Bearing Sediment Productivity and Stability in Ulleung Basin, East Sea, South Korea

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1752
Author(s):  
Jung-Tae Kim ◽  
Chul-Whan Kang ◽  
Ah-Ram Kim ◽  
Joo Yong Lee ◽  
Gye-Chun Cho
Keyword(s):  
Numerical Analysis ◽  
Methane Hydrate ◽  
Input Parameter ◽  
Ulleung Basin ◽  
Optimal Method ◽  
Permeability Model ◽  
Proposed Model ◽  
Hydrate Saturation ◽  
Ground Stability ◽  
Hydrate Bearing Sediments

Methane hydrate has attracted attention as a next-generation resource, and many researchers have conducted various studies to estimate its productivity. Numerical simulation is the optimal method for estimating methane gas productivity. Meanwhile, using a reasonable input parameter is essential for obtaining accurate numerical modeling results. Permeability is a geotechnical property that exhibits the greatest impact on productivity. The permeability of hydrate-bearing sediment varies based on the sediment pore structure and hydrate saturation. In this study, an empirical permeability model was derived from experimental data using soil specimens from the Ulleung Basin, and the model was applied in numerical analysis to evaluate the sediment gas productivity and ground stability. The gas productivity and stability of hydrate-bearing sediments were compared by applying a widely used permeability model and the proposed model to a numerical model. Additionally, a parametric study was performed to examine the effects of initial hydrate saturation on the sediment gas productivity and stability. There were significant differences in the productivity and stability analysis results according to the proposed permeability model. Therefore, it was found that for accurate numerical analysis, a regional permeability model should be applied.

Experimental Study on the In Situ Mechanical Properties of Methane Hydrate-Bearing Sediments

2013 ◽  
Vol 275-277 ◽  
pp. 326-331 ◽  
Author(s):  
Zhong Ming Sun ◽  
Jian Zhang ◽  
Chang Ling Liu ◽  
Shi Jun Zhao ◽  
Yu Guang Ye
Keyword(s):  
Shear Strength ◽  
Methane Hydrate ◽  
Failure Time ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
Hydrate Saturation ◽  
Confining Pressures ◽  
Coulomb Failure Criterion ◽  
Hydrate Bearing Sediments

TDR was introduced to solve the problem of how to measure hydrate saturation accurately. Then a series of un-drained triaxial tests were carried out on methane hydrate-bearing sediments under various conditions with effective confining pressures at 1, 2 and 4 MPa, average hydrate saturations at 15.71, 35.7 and 56.49% and strain rate at 0.8%/min. The results indicate that the shear strength increases with the increases of effective confining pressure and hydrate saturation, but the maximum failure time decreases with the increasing effective confining pressures. According to Mohr-Coulomb failure criterion, the shear strength of methane hydrate-bearing sediments was analyzed. It can be found that the internal friction angles are not sensitive to hydrate saturation, but the cohesion shows a high hydrate saturation dependency.

scholarly journals Thermo-Hydro-Mechanical Coupled Modeling of Methane Hydrate-Bearing Sediments: Formulation and Application

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2178 ◽  
Author(s):  
Maria De La Fuente ◽  
Jean Vaunat ◽  
Héctor Marín-Moreno
Keyword(s):  
Methane Hydrate ◽  
Mechanical Response ◽  
Solid Phase ◽  
Production Method ◽  
Triaxial Tests ◽  
Coupled Modeling ◽  
Mechanical Formulation ◽  
Hydrate Saturation ◽  
Sediment Deformation ◽  
Hydrate Bearing Sediments

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.

scholarly journals Wave Propagation Characteristics in Gas Hydrate-Bearing Sediments and Estimation of Hydrate Saturation

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 804
Author(s):  
Lin Liu ◽  
Xiumei Zhang ◽  
Xiuming Wang
Keyword(s):  
Gas Hydrate ◽  
Clay Content ◽  
Clean Energy ◽  
Compressional Wave ◽  
Physical Parameters ◽  
Well Log ◽  
Log Data ◽  
Phase Velocities ◽  
Hydrate Saturation ◽  
Hydrate Bearing Sediments

Natural gas hydrate is a new clean energy source in the 21st century, which has become a research point of the exploration and development technology. Acoustic well logs are one of the most important assets in gas hydrate studies. In this paper, an improved Carcione–Leclaire model is proposed by introducing the expressions of frame bulk modulus, shear modulus and friction coefficient between solid phases. On this basis, the sensitivities of the velocities and attenuations of the first kind of compressional (P1) and shear (S1) waves to relevant physical parameters are explored. In particular, we perform numerical modeling to investigate the effects of frequency, gas hydrate saturation and clay on the phase velocities and attenuations of the above five waves. The analyses demonstrate that, the velocities and attenuations of P1 and S1 are more sensitive to gas hydrate saturation than other parameters. The larger the gas hydrate saturation, the more reliable P1 velocity. Besides, the attenuations of P1 and S1 are more sensitive than velocity to gas hydrate saturation. Further, P1 and S1 are almost nondispersive while their phase velocities increase with the increase of gas hydrate saturation. The second compressional (P2) and shear (S2) waves and the third kind of compressional wave (P3) are dispersive in the seismic band, and the attenuations of them are significant. Moreover, in the case of clay in the solid grain frame, gas hydrate-bearing sediments exhibit lower P1 and S1 velocities. Clay decreases the attenuation of P1, and the attenuations of S1, P2, S2 and P3 exhibit little effect on clay content. We compared the velocity of P1 predicted by the model with the well log data from the Ocean Drilling Program (ODP) Leg 164 Site 995B to verify the applicability of the model. The results of the model agree well with the well log data. Finally, we estimate the hydrate layer at ODP Leg 204 Site 1247B is about 100–130 m below the seafloor, the saturation is between 0–27%, and the average saturation is 7.2%.

Geomechanical Responses During Gas Hydrate Production Induced by Depressurization

2016 ◽  
Author(s):  
Ah-Ram Kim ◽  
Gye-Chun Cho ◽  
Joo-Yong Lee ◽  
Se-Joon Kim
Keyword(s):  
Methane Hydrate ◽  
Fossil Fuel ◽  
Gas Production ◽  
Field Scale ◽  
Production Well ◽  
Physical Processes ◽  
Hydrate Dissociation ◽  
Thermal Changes ◽  
New Energy ◽  
Hydrate Bearing Sediments

Methane hydrate has been received large attention as a new energy source instead of oil and fossil fuel. However, there is high potential for geomechanical stability problems such as marine landslides, seafloor subsidence, and large volume contraction in the hydrate-bearing sediment during gas production induced by depressurization. In this study, a thermal-hydraulic-mechanical coupled numerical analysis is conducted to simulate methane gas production from the hydrate deposits in the Ulleung basin, East Sea, Korea. The field-scale axisymmetric model incorporates the physical processes of hydrate dissociation, pore fluid flow, thermal changes (i.e., latent heat, conduction and advection), and geomechanical behaviors of the hydrate-bearing sediment. During depressurization, deformation of sediments around the production well is generated by the effective stress transformed from the pore pressure difference in the depressurized region. This tendency becomes more pronounced due to the stiffness decrease of hydrate-bearing sediments which is caused by hydrate dissociation.

Quantification of methane hydrate formation in the Large-scale Reservoir Laboratory Simulator (LARS) by numerical simulations

2021 ◽  
Author(s):  
Zhen Li ◽  
Thomas Kempka ◽  
Erik Spangenberg ◽  
Judith Schicks
Keyword(s):  
Gas Hydrates ◽  
Methane Hydrate ◽  
Large Scale ◽  
Hydrate Formation ◽  
Simulation Environment ◽  
Transport Simulation ◽  
Chemistry Research ◽  
Research Activities ◽  
In Situ Conditions ◽  
Hydrate Bearing Sediments

<p>Natural gas hydrates are considered as one of the most promising alternatives to conventional fossil energy sources, and are thus subject to world-wide research activities for decades. Hydrate formation from methane dissolved in brine is a geogenic process, resulting in the accumulation of gas hydrates in sedimentary formations below the seabed or overlain by permafrost. The LArge scale Reservoir Simulator (LARS) has been developed (Schicks et al., 2011, 2013; Spangenberg et al., 2015) to investigate the formation and dissociation of gas hydrates under simulated in-situ conditions of hydrate deposits. Experimental measurements of the temperatures and bulk saturation of methane hydrates by electrical resistivity tomography have been used to determine the key parameters, describing and characterising methane hydrate formation dynamics in LARS. In the present study, a framework of equations of state to simulate equilibrium methane hydrate formation in LARS has been developed and coupled with the TRANsport Simulation Environment (Kempka, 2020) to study the dynamics of methane hydrate formation and quantify changes in the porous medium properties in LARS. We present our model implementation, its validation against TOUGH-HYDRATE (Gamwo & Liu, 2010) and the findings of the model comparison against the hydrate formation experiments undertaken by Priegnitz et al. (2015). The latter demonstrates that our numerical model implementation is capable of reproducing the main processes of hydrate formation in LARS, and thus may be applied for experiment design as well as to investigate the process of hydrate formation at specific geological settings.</p><p>Key words: dissolved methane; hydrate formation; hydration; python; permeability.</p><p>References</p><p>Schicks, J. M., Spangenberg, E., Giese, R., Steinhauer, B., Klump, J., & Luzi, M. (2011). New approaches for the production of hydrocarbons from hydrate bearing sediments. Energies, 4(1), 151-172, https://doi.org/10.3390/en4010151</p><p>Schicks, J. M., Spangenberg, E., Giese, R., Luzi-Helbing, M., Priegnitz, M., & Beeskow-Strauch, B. (2013). A counter-current heat-exchange reactor for the thermal stimulation of hydrate-bearing sediments. Energies, 6(6), 3002-3016, https://doi.org/10.3390/en6063002</p><p>Spangenberg, E., Priegnitz, M., Heeschen, K., & Schicks, J. M. (2015). Are laboratory-formed hydrate-bearing systems analogous to those in nature?. Journal of Chemical & Engineering Data, 60(2), 258-268, https://doi.org/10.1021/je5005609</p><p>Kempka, T. (2020) Verification of a Python-based TRANsport Simulation Environment for density-driven fluid flow and coupled transport of heat and chemical species. Adv. Geosci., 54, 67–77, https://doi.org/10.5194/adgeo-54-67-2020</p><p>Gamwo, I. K., & Liu, Y. (2010). Mathematical modeling and numerical simulation of methane production in a hydrate reservoir. Industrial & Engineering Chemistry Research, 49(11), 5231-5245, https://doi.org/10.1021/ie901452v</p><p>Priegnitz, M., Thaler, J., Spangenberg, E., Schicks, J. M., Schrötter, J., & Abendroth, S. (2015). Characterizing electrical properties and permeability changes of hydrate bearing sediments using ERT data. Geophysical Journal International, 202(3), 1599-1612, https://doi.org/10.1093/gji/ggv245</p>

scholarly journals Impact of hydrate saturation on water permeability in hydrate-bearing sediments

2019 ◽  
Vol 174 ◽  
pp. 696-703 ◽  
Author(s):  
Nariman Mahabadi ◽  
Sheng Dai ◽  
Yongkoo Seol ◽  
Jaewon Jang
Keyword(s):  
Water Permeability ◽  
Hydrate Saturation ◽  
Hydrate Bearing Sediments
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