A State-Dependent Constitutive Model for Gas Hydrate-Bearing Sediments Considering Cementing Effect

Abstract

This paper presents a state-dependent constitutive model for gas hydrate-bearing sediments (GHBS), considering the cementing effect for simulating the stress–strain behavior of GHBS. In this work, to consider the influence of hydrate on matrix samples in theory, some representative GHBS laboratory tests were analyzed, and it was found that GHBS has obvious state-related characteristics. At the same time, it was found that GHBS has high bonding strength. In order to describe these characteristics of GHBS, the cementation strength related to hydrate saturation is introduced in the framework of a sand state correlation model. In addition, in order to accurately reflect the influence of cementation on the hardening law of GHBS, the degradation rate of cementation strength is introduced, and the mixed hardening theory is adopted to establish the constitutive model. The model presented in this paper reproduces the experimental results of Masui et al. and Miyazaki et al., and the prediction performance of the model is satisfactory, which proves the rationality of this work.

Recent Advances in Methods of Gas Recovery from Hydrate-Bearing Sediments: A Review

“…The above key challenges are rooted in the existing research gaps on the strong multiphysics coupling relationship of thermal–hydraulic–mechanical–chemical (THMC) aspects in HBS during gas recovery (shown in Figure ). However, the multifield relationship is in the weak coupling stage, which simplifies the nonlinearity degree of HBS and makes the NGH development idealized. ,,, Moreover, given the unconsolidated nature of HBS, a complexly disturbed situation near the wellbore, vertical and horizontal heterogeneities of HBS, and weak coupling of THMC could be determined as the leading causes for the discrepancy in production behavior predicted by the THMC model and actual monitoring in the field. , The powerful interactions among THMC can be described as follows briefly: interactions between chemical and hydraulic fields The NGH dissociation/formation and water–ice phase transition under certain P – T are guaranteed to change the fluid flow parameters (e.g., porosity, the permeability of HBS). However, the variations in the pressure of HBS, in turn, affect their transition rate. interactions between chemical and thermal fields NGH formation/dissociation are exothermic/endothermic reactions, and ice formation and ice ablation are exothermic/endothermic reactions, respectively, directly determining the temporal and spatial distribution of the thermal field in HBS.…”

“…However, the multifield relationship is in the weak coupling stage, which simplifies the nonlinearity degree of HBS and makes the NGH development idealized. 140,386,396,397 Moreover, given the unconsolidated nature of HBS, a complexly disturbed situation near the wellbore, vertical and horizontal heterogeneities of HBS, and weak coupling of THMC could be determined as the leading causes for the discrepancy in production behavior predicted by the THMC model and actual monitoring in the field. 398,399 The powerful interactions among THMC can be described as follows briefly:…”

Acoustic Wave Propagation in a Borehole with a Gas Hydrate-Bearing Sediment

“…Natural gas hydrate is globally widespread in continental margin sediments and permafrost regions, it has been recognized as a potential energy source in the 21st century [1,2]. The exploration and development technology of natural gas hydrate has been a research hotspot in recent years [3][4][5][6][7]. Acoustic logging is one of the promising technologies in the interpretation of formations parameters underground [5,8], where the velocity from acoustic well logs can be used to distinguish gas hydrate layers along the depth of the borehole.…”

Physio-Chemical and Mineralogical Characteristics of Gas Hydrate-Bearing Sediments of the Kerala-Konkan, Krishna-Godavari, and Mahanadi Basins

“…An increase in the saturation of hydrate can increase the strength of sediments. The stability of gas hydrates can be affected by the salinity of pore water [25]. Increase in the salinity of pore water can decrease the hydrate formation temperature.…”