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 Consolidation of gas hydrate-bearing sediments with hydrate dissociation

2020 ◽  
Vol 205 ◽  
pp. 11007
Author(s):  
Maria De La Fuente ◽  
Jean Vaunat ◽  
Hector Marín-Moreno
Keyword(s):  
Effective Stress ◽  
Gas Hydrate ◽  
Hydrate Dissociation ◽  
Economic Production ◽  
Mechanical Formulation ◽  
Sediment Consolidation ◽  
Hydrate Saturation ◽  
Sediment Deformation ◽  
Hydrate Bearing Sediments ◽  
Hydrate Reservoirs

Quantifying sediment deformation induced by depressurization of gas hydrate reservoirs and hydrate dissociation is crucial for the safe and economic production of natural gas from hydrates, and for understanding hydrate-related natural geological risks. This study uses our recently developed fully-coupled Thermo-Hydro-Mechanical formulation for gas hydrate-bearing geological systems implemented in the 3D Code_Bright simulator. First, the model formulation is briefly presented. Then, the model is applied to reproduce published experimental consolidation tests performed on hydrate-bearing pressure-core sediments recovered from the Krishna–Godavari Basin (offshore of India) during the India National Gas Hydrate Project Expedition 02 (NGHP02). The numerical simulation reproduces the tests in which the sediment is loaded and unloaded prior and after hydrate dissociates via depressurization at constant effective stress. Our results successfully capture sediment collapse when hydrate dissociates at a mean effective stress above that of the host sediment consolidation curve. The mechanical constitutive model Hydrate-CASM also allows reproducing the experimentally observed changes in sediment swelling index with changes in hydrate saturation.

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 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.

scholarly journals The Distinct Elemental Analysis of the Microstructural Evolution of a Methane Hydrate Specimen under Cyclic Loading Conditions

Energies ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3694 ◽  
Author(s):  
Dong Wang ◽  
Bin Gong ◽  
Yujing Jiang
Keyword(s):  
Cyclic Loading ◽  
Methane Hydrate ◽  
Mechanical Response ◽  
Distinct Element ◽  
Constitutive Models ◽  
Slope Instability ◽  
Loading Conditions ◽  
Shear Process ◽  
Hydrate Saturation ◽  
Dynamic Loading Conditions

Submarine slope instability may be triggered by earthquakes and tsunamis. Methane hydrate sediments (MHS) are commonly buried under submarine slopes. Submarine slides would probably be triggered once the MHS are damaged under cyclic loading conditions. For this reason, it is essential to research the mechanical response of MHSs under dynamic loading conditions. In this study, a series of drained cyclic biaxial compressive tests with constant stress amplitudes were numerically carried out with the distinct element method (DEM). The cyclic loading number decreased as the hydrate saturation (Sh) increased when the MHS were damaged. The failure mode of the MHS was shown to be dependent on the dynamic stress amplitude and hydrate saturation. The microstructure of MHS during the cyclic loading shear process was also analyzed. The results can help us to understand the mechanical behavior of MHS during the cyclic loading process and develop micromechanical-based constitutive models.

Applicability of Duncan-Chang Model and its Modified Versions to Methane Hydrate-Bearing Sands

2011 ◽  
Vol 347-353 ◽  
pp. 3384-3387 ◽  
Author(s):  
Ju Hua Xiong ◽  
Xiao Yong Kou ◽  
Fang Liu ◽  
Ming Jing Jiang
Keyword(s):  
Methane Hydrate ◽  
Constitutive Models ◽  
Constitutive Law ◽  
Triaxial Tests ◽  
Elastic Model ◽  
Clathrate Compound ◽  
Constitutive Response ◽  
Nonlinear Elastic ◽  
Hydrate Bearing Sediments ◽  
Chang Model

Methane hydrate is ice-like clathrate compound that attracts global attention due to its huge potential as a future energy source. The constitutive law of methane hydrate-bearing sediments remains unknown and becomes a barrier in sustainable exploitation of methane hydrate from marine sediments. The Duncan-Change model is a nonlinear elastic model which was widely accepted by the geotechnical community in approximating the constitutive response of geo-materials. This model and its evolved versions were employed in this study to model the stress-strain response observed in triaxial tests on methane hydrate-bearing sands. Duncan-Chang type models capture well the strain hardening behaviors. However, they fall short of incorporating the dependency of temperature and saturation degree of methane hydrate, which have to be taken into account in future constitutive models of methane hydrate-bearing deposits.

scholarly journals Multistage Triaxial Tests on Laboratory‐Formed Methane Hydrate‐Bearing Sediments

2018 ◽  
Vol 123 (5) ◽  
pp. 3347-3357 ◽  
Author(s):  
Jeong‐Hoon Choi ◽  
Sheng Dai ◽  
Jeen‐Shang Lin ◽  
Yongkoo Seol
Keyword(s):  
Methane Hydrate ◽  
Triaxial Tests ◽  
Hydrate Bearing Sediments

scholarly journals Formation of a Low-Density Liquid Phase during the Dissociation of Gas Hydrates in Confined Environments

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 590
Author(s):  
Lihua Wan ◽  
Xiaoya Zang ◽  
Juan Fu ◽  
Xuebing Zhou ◽  
Jingsheng Lu ◽  
...  
Keyword(s):  
Natural Gas ◽  
Methane Hydrate ◽  
Phase State ◽  
Solid Phase ◽  
Potential Method ◽  
Methane Hydrates ◽  
Low Density ◽  
Hydrate Dissociation ◽  
State Of Water ◽  
Confined Environment

The large amounts of natural gas in a dense solid phase stored in the confined environment of porous materials have become a new, potential method for storing and transporting natural gas. However, there is no experimental evidence to accurately determine the phase state of water during nanoscale gas hydrate dissociation. The results on the dissociation behavior of methane hydrates confined in a nanosilica gel and the contained water phase state during hydrate dissociation at temperatures below the ice point and under atmospheric pressure are presented. Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffraction (PXRD) were used to trace the dissociation of confined methane hydrate synthesized from pore water confined inside the nanosilica gel. The characterization of the confined methane hydrate was also analyzed by PXRD. It was found that the confined methane hydrates dissociated into ultra viscous low-density liquid water (LDL) and methane gas. The results showed that the mechanism of confined methane hydrate dissociation at temperatures below the ice point depended on the phase state of water during hydrate dissociation.

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%.

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