Modeling the mechanical response of gas hydrate reservoirs in triaxial stress space

Wu, Yang; Li, Neng; Hyodo, Masayuki; Gu, M.; Cui, Jie; Spencer, Billie F.

doi:10.1016/j.ijhydene.2019.08.119

Cited by 52 publications

(16 citation statements)

References 48 publications

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“…Several related studies [41][42][43][44][45][46][47][48][49][50] have shown that particle breakage is an energy dissipation process. Therefore, this paper analyzes the variation in the particle breakage of coral gravelly sand under different water contents from the perspective of energy.…”

Section: Relationship Between Particle Breakage and Plastic Workmentioning

confidence: 99%

Experimental Study on the Impact of Water Content on the Strength Parameters of Coral Gravelly Sand

Wang

Shen

et al. 2020

JMSE

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The effect of capillary water caused by heavy rainfall and groundwater level fluctuations can induce the erosion and collapse of island reef coral sand foundations. Here, the effects of water content (ω) on the shear strength parameters of coral gravelly sand are analyzed at the macro and micro scales by laboratory consolidated-drained triaxial compression and nuclear magnetic resonance tests. Furthermore, particle breakage characteristics of coral gravelly sand under the static load are discussed. With increasing ω, (1) the internal friction angle increases slightly (<1°) then decreases; (2) the apparent cohesion is more sensitive to the change in the ω; (3) with an increase from 5.4% to 21.3%, the bound water content remains almost unchanged; (4) the capillary water content is the main factor impacting the apparent cohesion; (5) the increase in free water content is the internal cause of the decreasing internal friction angle of coral gravelly sand with ω > 11.1%; and (6) the particle breakage increases, and there is an approximately linear relationship between the median particle diameter (d50) and relative breakage index (Br). The established physical model can reflect the influence of water content and plastic work and describe the evolution law of particle breakage.

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Section: Relationship Between Particle Breakage and Plastic Workmentioning

confidence: 99%

Experimental Study on the Impact of Water Content on the Strength Parameters of Coral Gravelly Sand

Wang

Shen

et al. 2020

JMSE

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“…By assuming c k � k/(1 + e 0 ) and substituting equation (26) into equations (24) and (25), we obtain…”

Section: Hardening Parametermentioning

confidence: 99%

“…e foregoing constitutive models are widely used in simulating the stress-strain characteristics and dilatancy of sandy soil. ey also provide ideas for other scholars to establish constitutive model of sand soil considering various influencing factors [24].…”

Section: Introductionmentioning

confidence: 99%

A Constitutive Model for Saturated Gravelly Sand Based on Higher‐Order Dilatancy Equation

Zhang

Luo

Zhu

et al. 2020

Advances in Civil Engineering

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A standard stress path triaxial test system was applied to carry out conventional triaxial shearing tests for gravelly sands under confining pressures ranging from 50 kPa to 400 kPa at the initial relative densities of 0.15, 0.35, 0.55, and 0.75, respectively. The test results show that all the samples of gravelly sand present strain hardening and shear contraction during the process of shearing test. Additionally, gravelly sands are significantly affected by the initial relative density. The hardening degree of gravelly sand samples rises in line with increasing initial relative densities during shearing tests. When initial relative densities Dr are at 0.15 and 0.35, the volume shrinkage of samples decreases with the increasing confining pressures. Instead, when initial relative densities Dr are at 0.55 and 0.75, the volume shrinkage of samples increases with the growth of confining pressures. To describe these triaxial shearing mechanical properties of gravelly sands, a higher-order dilatancy equation was proposed based on the concept of a super yield surface. A constitutive model which can describe the mechanical properties of gravelly sand was established when the associated flow laws were applied to compare with the results of the triaxial shearing test under the consolidated drained condition. The comparison results showed that the proposed model can reflect the strain hardening and shear contraction characteristics of gravelly sands from low to high confining pressures under different initial relative densities.

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“…Moreover, it should be noted that ice and hydrate in the permafrost maintain the stability of the skeleton under the condition of perennial low temperature [20]. The original balance of permafrost reservoir will be broken by operation of the drilling, well completion, well cementation process, and production, like operation fluids will increase the temperature of reservoirs and melt the ice skeleton [19,[21][22][23][24][25]. The dissociation of hydrate skeleton by increased temperature and production also will reduce the strength of the soil skeleton.…”

Section: Introductionmentioning

confidence: 99%

Thermal Diffusion Characteristics in Permafrost during the Exploitation of Gas Hydrate

et al. 2021

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Methane hydrate is the vast potential resources of natural gas in the permafrost and marine areas. Due to the occurrence of phase transition, the gas hydrate is dissociated into gas and water and absorbs lots of heat. The incomprehensive knowledge of endothermic reaction in permafrost sediments still restricted the production efficiency of hydrate commercial development. This endothermic reaction leads to a complex thermal diffusion in permafrost, which directly influences the phase transition in turn. In this research, the heat during the exploitation is transferred in two forms (specific heat and latent heat). Besides, the melting point is not constant but depends on the pore size of the reservoir rock. According to these features, a thermal diffusion model with phase transition is established. To calculate the governing equation, the pore size distribution is obtained by using the nuclear magnetic resonance (NMR) method. The heating tests are conducted and simulated to calibrate the coefficient (i.e., transverse surface relaxivity) of NMR. Then, the temperature field evolution of the hydrate reservoir during the exploitation is simulated by using the calibrated values. The results show that the temperature curves have a typical plateau related to the pore size distribution, which is effective to obtain the surface relaxivity. The heat transfer is remarkably limited by the endothermic effect of the phase transition. The hydrate recovery efficiency may depend largely on the heating capacity of the engineering operation and the rate of gas production. Compared to the conventional petroleum industry, it is significant to control the maximum temperature and temperature distribution in engineering operations during hydrate development. This research on the temperature behavior during onshore permafrost hydrate production could provide the theoretical support to control heat behavior of offshore hydrate production.

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Modeling the mechanical response of gas hydrate reservoirs in triaxial stress space

Cited by 52 publications

References 48 publications

Experimental Study on the Impact of Water Content on the Strength Parameters of Coral Gravelly Sand

Experimental Study on the Impact of Water Content on the Strength Parameters of Coral Gravelly Sand

A Constitutive Model for Saturated Gravelly Sand Based on Higher‐Order Dilatancy Equation

Thermal Diffusion Characteristics in Permafrost during the Exploitation of Gas Hydrate

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