An Application of the Results from the Large-Scale Thermal Stimulation Method of Methane Hydrate Dissociation to the Field Tests

Abstract

Methane hydrate formation and the gas recovery from the hydrates using the thermal stimulation method was studied in a large-scale laboratory reactor. A large-scale laboratory reactor (59 L volume) was used in this study. The efficiencies of gas recovery and energy utilization were studied over two different values of initial hydrate saturation (30% and 50%) and three different values of heating rates (20, 50, and 100 W). Results obtained from the tests demonstrate that with the initial hydrate saturation (SH) remaining constant (50% SH); total recovery of methane increases from 40% to 52% to 73% with a heating rate increase from 20 W to 50 W to 100 W. The average thermal efficiency, however, decreases from 86% to 84% to 82% over the same heating rate range. Alternately at a constant heating rate (100 W), total recovery of methane increased from 67% to 74% when an initial hydrate saturation was increased from 30% to 50%. We show that maintaining a constant heating rate throughout the dissociation is not the most efficient procedure. Instead, starting with a low heating rate then increasing it when methane output starts to decrease will be more effective. This suggests that accurate knowledge of the saturation percentage of a chosen hydrate reservoir will enable efficient energy use when recovering methane. We also found that the free water generated during the dissociation and the free water present initially in the reservoir play a major role in carrying the heat front to distant locations in the reservoir hence increasing the gas recovery. We recommend that in the higher hydrate saturation reservoirs, which may lack the free water; the down-hole combustion method will benefit from an injection of hot water in the initial stages, supplying a small amount of heat for the dissociation but providing the free water for convection of heat to the outer regions.

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).…”

Impact of Modified Silica Beads on Methane Hydrate Formation in a Fixed-Bed Reactor

“…Previous gas hydrate research has focused on the exploitation of natural gas hydrate reservoirs − and on the field of flow assurance. Here, unintentional gas hydrate formation in pipelines results in unsafe operating conditions, defects, and annual economic costs in the range of millions of dollars. − Nowadays, new application possibilities, where targeted formation is favored, have been introduced in the fields of gas storage and transport, , carbon dioxide sequestration, , gas separation, − desalination, , biotechnology, , food engineering, , and phase-change materials. , Thus, the use of gas hydrate storage seems to be a very promising approach, as gas hydrate storage is capable of storing approximately 170 N m 3 /m 3 of natural gas but at more moderate conditions compared to compressed or liquefied natural gas while providing low safety risks toward explosions …”

Numerical Investigation into the Development Performance of Gas Hydrate by Depressurization Based on Heat Transfer and Entropy Generation Analyses

“…According to the analyses of six hydrate exploitation experiments with a variety of methods and wellbore layouts, Liu et al [ 38 ] concluded that it was especially important to take advantage of the heat provided by the outside environment as much as possible for raising the energy efficiency. Tupsakhare et al [ 39 ] discovered that the transportation of the liquid water could carry more heat to distant areas through convection and thus enhance the gas recovery. By conducting numerical analyses of the dissociation properties of gas hydrate around ice point, Li et al [ 29 ] arrived at a conclusion that the released latent heat during ice generation could promote the dissociation rate to some extent when the blockage effect of ice was not pronounced.…”