Numerical simulations for analyzing deformation characteristics of hydrate-bearing sediments during depressurization

Abstract

Natural gas hydrates have been treated as a potential energy resource for decades. Understanding geomechanical properties of hydrate-bearing porous media is an essential to protect the safety of individuals and devices during hydrate production. In this work, a numerical simulator named GrapeFloater is developed to study the deformation behavior of hydrate-bearing porous media during depressurization, and the numerical simulator couples multiple processes such as conductive-convective heat transfer, two-phase fluid flow, intrinsic kinetics of hydrate dissociation, and deformation of solid skeleton. Then, a depressurization experiment is carried out to validate the numerical simulator. A parameter sensitivity analysis is performed to discuss the deformation behavior of hydrate-bearing porous media as well as its effect on production responses. Conclusions are drawn as follows: the numerical simulator named GrapeFloater predicts the experimental results well; the modulus of hydrate-bearing porous media has an obvious effect on production responses; final deformation increases with decreasing outlet pressure; both the depressurization and the modulus decrease during hydrate dissociation contribute to the deformation of hydrate-bearing porous media.

Cementation Failure Behavior of Consolidated Gas Hydrate‐Bearing Sand

“…On the other hand, a cubic unit of NGHs can contain approximately 180 cubic units of natural gas at standard temperature and pressure (Servio & Englezos, 2002). Therefore, NGHs have attracted much attention from academia, the industry, and the government, which has resulted in great research efforts on exploitation technology (depressurization, thermal stimulation, chemical inhibitor injection, CH 4 -CO 2 replacement, and fluidization mining method; Koh et al, 2016;Liu et al, 2017;Rutqvist et al, 2009;Tupsakhare et al, 2017;Wallmann et al, 2018;Wang et al, 2014), flow assurance (Gao, 2008;Gbaruko et al, 2007;Zerpa et al, 2011), and energy conversion (Yoneda et al, 2015).…”

Laboratory Investigation Into the Formation and Dissociation Process of Gas Hydrate by Low‐Field NMR Technique

“…The most common guest molecule in naturally occurring gas hydrate is methane (Waite et al, ). Gas hydrate bearing formations in nature are generally multiphase systems consisting of a formation grain matrix with water, gas, and hydrate occupying the pore space (Liu et al, ; Sun & Goldberg, ). Scientific interest in gas hydrate has increased tremendously in recent decades due to the decline of conventional fossil fuel resources.…”

Maximum Sizes of Fluid-Occupied Pores within Hydrate-Bearing Porous Media Composed of Different Host Particles

“…It is shown that c ic * values generally stay close to the horizontal red line c ic * = 1 (Figure 7(c)), and c if * values go through an evolutionary process from below to above the red curve c if (Figure 7(d)). These discrepancies between numerical simulated c ic,f * data and corresponding theoretical models (i.e., Equations (8) and (12)) are mainly due to differences in hydrate pore habits since grain-coating and pore-filling hydrate growths can hardly follow the uniform and self-similar way ( Figure 5 Figure 8. It is obvious that hydrate saturation and morphology effects on c i and c i * values are similar with those on c h and c h * values.…”

“…Currently, the exploitation of this potential energy resource is still not economically feasible and requires innovative production methods and techniques [4,5]. New methods and techniques should be well evaluated by numerical simulators prior to field applications, and results of these numerical evaluations largely depend on proper characterizations of coupled processes and appropriate quantifications of physical properties of hydrate-bearing sediments [6][7][8][9].…”