Hydrate morphology and mechanical behavior of hydrate-bearing sediments: a critical review

Abstract

and differences of the hydrate morphology in the HBS synthesized using the excess-gas and excess-water methods are highlighted. The available experimental data on the small-strain stiffness, strength, and stressstrain behavior are critically selected and grouped into two categories based on the synthesizing methods. It has been creatively discovered that most mechanical parameters (e.g., bulk modulus, shear modulus, cohesion, dilation angle) share a concave power relationship with the hydrate saturation S H for the HBS synthesized using the excess-water method. While it is a convex power relationship for the bulk modulus, shear modulus, and dilation angle, and a linear relationship for the cohesion c when the HBS is synthesized using the excess-gas method. These observations contribute to establishing the conceptual model reflecting the particle-level failure mechanism of the Abstract Natural gas hydrate is a promising energy resource in the future because of its little contamination and huge reserve. However, gas exploitation may induce large deformation and failure of the seabed due to a reduction in the stiffness and strength of the hydrate-bearing sediment (HBS). Therefore, it is essential to investigate the mechanical behavior of the HBS for safe and efficient gas exploitation. Additionally, it is widely acknowledged that the hydrate morphology inherently affects the mechanical behavior of the HBS. This paper aims to critically synthesize the information on the hydrate morphology and mechanical behavior of the HBS available in the literature to facilitate the application of the research result into engineering practice and provide guidance for future investigation. Hydrate morphology is identified firstly both in natural and synthesized HBS. The similarities

Mechanical Properties of Gas Hydrate-Bearing Sediments Influenced by Multiple Factors: A Comprehensive Review of Triaxial Tests

“…The cementation of the hydrate provides additional resistance to the rotational slip of the particles, so as the shear process proceeds the cementation of the hydrate decreases, and the specimen exhibits strain-softening behavior. 104 3.3. Factors Influencing Mechanical Properties of HBS.…”

“…(b) Undrained conditions: b 1 : Stress-axial strain curve, b 2 : Pore pressure-axial strain curve. Reproduced with permission from ref . Copyright 2022 Springer Nature Switzerland.…”

“…The shearing process is accompanied by the occurrence of shear expansion, which causes the pore pressure to change from positive to negative values. The cementation of the hydrate provides additional resistance to the rotational slip of the particles, so as the shear process proceeds the cementation of the hydrate decreases, and the specimen exhibits strain-softening behavior …”

Comprehensive Review and Perspectives of CO2 Hydrate Storage in Subseafloor Saline Sediments: Formation, Stability, and Optimization Strategies

“…Fine-grained sediments possess a larger surface area per unit volume, enabling more extensive contact between CO 2 and water molecules and expediting the nucleation and growth of hydrate crystals. 25 Conversely, coarser sediments might exhibit slower formation kinetics due to reduced interfacial contact between CO 2 and water molecules. 26,27 The presence and distribution of clay minerals within sediments also notably influence CO 2 hydrate pore-scale mechanisms�ranging from localized damage in low saturation to enhanced strength in highly saturated sediments.…”

“…Moreover, the grain size distribution within sediments significantly impacts CO 2 hydrate formation mechanisms. Fine-grained sediments possess a larger surface area per unit volume, enabling more extensive contact between CO 2 and water molecules and expediting the nucleation and growth of hydrate crystals . Conversely, coarser sediments might exhibit slower formation kinetics due to reduced interfacial contact between CO 2 and water molecules. , The presence and distribution of clay minerals within sediments also notably influence CO 2 hydrate formation.…”