Experimental Techniques for Mechanical Properties of Gas Hydrate-Bearing Sediments

2013 ◽  
Vol 275-277 ◽  
pp. 316-321 ◽  
Author(s):  
Jian Zhang ◽  
Yu Guang Ye ◽  
Chang Ling Liu ◽  
Zhong Ming Sun ◽  
Lei Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Gas Hydrate ◽  
Experimental Techniques ◽  
Marine Geology ◽  
Natural Gas Hydrate ◽  
Hydrate Saturation ◽  
Basic Parameters ◽  
National Patent ◽  
The Stability ◽  
Hydrate Bearing Sediments

The mechanical properties of gas hydrate-bearing sediments are important basic parameters during natural gas hydrate drilling and exploitation. It’s very hard to get and preserve the actual gas hydrate specimens for the measurements of these characteristics. Experimental techniques for mechanical properties of gas hydrate-bearing sediments are essential and unique because of the special high pressure and low temperature conditions for the stability of gas hydrate. Qingdao Institute of Marine Geology has developed an experimental equipment (Chinese National patent No. ZL 2010 2 0253067.3) to study the variation of mechanical properties along with gas hydrate saturation in different sediments. The combination, configuration and advantages of the equipment, as well as some preliminary experimental results were introduced in this article.

scholarly journals Stability Analysis of Near-Wellbore Reservoirs Considering the Damage of Hydrate-Bearing Sediments

2019 ◽  
Vol 7 (4) ◽  
pp. 102 ◽  
Author(s):  
Zhang ◽  
Xia ◽  
Xu ◽  
Han
Keyword(s):  
Gas Hydrate ◽  
Structural Damage ◽  
Coupled Model ◽  
Damage Variable ◽  
Field Coupling ◽  
Mechanical Field ◽  
Hydrate Saturation ◽  
Key Issues ◽  
The Stability ◽  
Hydrate Bearing Sediments

The stability of hydrate-bearing near-wellbore reservoirs is one of the key issues in gas hydrate exploitation. In most previous investigations, the damage evolution process of the sediment structure and its effect on near-wellbore reservoir stability have been neglected. Therefore, the damage variable is introduced into a multi-field coupled model based on continuous damage theory and multi-field coupling theory. A thermo-hydro-mechanical-chemical (THMC) multi-field coupling mathematical model considering damage of hydrate-bearing sediments is established. The effects of damage of hydrate-bearing sediments on the thermal field, seepage field, and mechanical field are considered. Finally, the distributions of hydrate saturation, pore pressure, damage variable, and effective stress of a near-wellbore reservoir in gas hydrate exploitation by depressurization are calculated, and the stability of a hydrate-bearing near-wellbore reservoir is analyzed using the model. Through calculation and analysis, it is found that structural damage of hydrate-bearing sediments has an adverse effect on the stability of hydrate-bearing near-wellbore reservoirs. The closer to the wellbore, the worse the reservoir stability, and the near-wellbore reservoir stability is the worst in the direction of minimum horizontal ground stress.

A Study on the Differences of Mechanical Properties between CH4 and CO2 Hydrate-Bearing Sediments

2013 ◽  
Vol 353-356 ◽  
pp. 1240-1244 ◽  
Author(s):  
Yuan Luo ◽  
Yong Chen Song ◽  
Wei Guo Liu ◽  
Jia Fei Zhao ◽  
Yun Fei Chen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Gas Hydrate ◽  
Triaxial Compression ◽  
Triaxial Tests ◽  
Long Term Storage ◽  
Replacement Method ◽  
Three Stages ◽  
The Stability ◽  
Hydrate Bearing Sediments

The CH4-CO2replacement method to recover CH4from hydrate-bearing sediments has received great attention because it enables the long term storage of CO2and is expected to maintain the stability of gas hydrate-bearing sediments. This paper extends our previous study of the stability of CH4hydrate-bearing sediments to CO2hydrate-bearing sediments to evaluate the safety of the CH4-CO2replacement method. Low temperature, high pressure triaxial compression apparatus was used to measure the mechanical properties of CO2hydrate-bearing sediments. The triaxial tests results for CH4and CO2hydrate-bearing sediments were then compared. It was found that the failure mode of both the CO2and CH4hydrate-bearing sediments was a bulging deformation at mid-height on the samples. Moreover, the stress-strain curves of both the CO2and CH4hydrate-bearing sediments appear to be hyperbolic in shape, and could be divided into three stages: the quasi-elastic stage, the hardening stage and the yield stage. However, the strength of the CO2hydrate-bearing sediments was approximately 15% larger than that of the CH4hydrate-bearing sediments under the same conditions. The results imply that the stability of gas hydrate-bearing sediments could be maintained using the CH4-CO2replacement method to recover CH4from these sediments.

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%.

New Predictive Model for Relative Permeability of Deformable Gas Hydrate-Bearing Sediments

2020 ◽  
Author(s):  
Gang Lei ◽  
Qinzhuo Liao ◽  
Patil Shirish
Keyword(s):  
Relative Permeability ◽  
Gas Hydrate ◽  
Water Phase ◽  
Flow In Porous Media ◽  
World Population ◽  
Water Mixture ◽  
Gas Saturation ◽  
Hydrate Saturation ◽  
Stress Dependent ◽  
Hydrate Bearing Sediments

<p>Global energy demand is expected to grow significantly as the world population and the standard of living increase in the coming decades. As a potential source of energy, gas hydrate, which is a crystalline compound of gas-water mixture formed in stable of high pressure and low temperature, has been intensively investigated in the past few decades. In this work, a new analytical model is derived to study the effect of hydrate saturation on stress-dependent relative permeability behavior of hydrate-bearing sediments. The proposed relative permeability model solves the steady-state Navier-Stokes equations for gas-water two-phase flow in porous media with hydrates. It considers water saturation, hydrate saturation, viscosity ratio and hydrate-growth pattern, and is adequately validated with the experimental results in existing literatures. The model demonstrates that gas-water relative permeability in wall coating hydrates (WC hydrates) is larger than that in pore filling hydrates (PF hydrates). For WC hydrates, water phase relative permeability monotonically decreases as gas saturation increases. However, for PF hydrates, water phase relative permeability firstly increases and then decreases with the increase of gas saturation, which can be explained by the “lubricative” effect of the gas phase that exists between the water phase and hydrates. This work constitutes a comprehensive investigation of stress-dependent relative permeability in deformable hydrate-bearing sediments, which is a key issue for sustainable gas production. It not only provides theoretical foundations for quantifying relative permeability in hydrate-bearing sediments, but also can be used to estimate pore-scale parameters and rock lithology of gas hydrate-bearing sediments using inverse modeling.</p>

A new low-cost drilling fluid for drilling in natural gas hydrate-bearing sediments

2016 ◽  
Vol 33 ◽  
pp. 934-941 ◽  
Author(s):  
Tianle Liu ◽  
Guosheng Jiang ◽  
Ping Zhang ◽  
Jiaxin Sun ◽  
Huicui Sun ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Hydrate ◽  
Drilling Fluid ◽  
Low Cost ◽  
Natural Gas Hydrate ◽  
Hydrate Bearing Sediments
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