Numerical analysis of methane hydrate decomposition experiments by depressurization around freezing point in porous media

Li, Bo; Liang, Yunpei; Li, Xiao-Sen; Wu, Huayue

doi:10.1016/j.fuel.2015.07.048

Cited by 60 publications

(21 citation statements)

References 34 publications

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“…In the early stage of the production (Figure 12a), large amount of sensible heat of the hydrate deposit is consumed by the hydrate dissociation under the sharp depressurization driving force. Then some of the water in the pores is transformed into solid ice near the production wells to provide additional latent heat for further hydrate dissociation [37]. The ice transition process gets more severe until the injected heat is successfully transferred to these areas, as shown in Figure 12b.…”

Section: Comparison Of the 5s And 2s Systemsmentioning

confidence: 99%

Assessment of Gas Production Potential from Hydrate Reservoir in Qilian Mountain Permafrost Using Five-Spot Horizontal Well System

2015

Energies

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Abstract:The main purpose of this study is to investigate the production behaviors of gas hydrate at site DK-2 in the Qilian Mountain permafrost using the novel five-spot well (5S) system by means of numerical simulation. The whole system is composed of several identical units, and each single unit consists of one injection well and four production wells. All the wells are placed horizontally in the hydrate deposit. The combination method of depressurization and thermal stimulation is employed for hydrate dissociation in the system. Simulation results show that favorable gas production and hydrate dissociation rates, gas-to-water ratio, and energy ratio can be acquired using this kind of multi-well system under suitable heat injection and depressurization driving forces, and the water production rate is manageable in the entire production process under current technology. In addition, another two kinds of two-spot well (2S) systems have also been employed for comparison. It is found that the 5S system will be more commercially profitable than the 2S configurations for gas production under the same operation conditions. Sensitivity analysis indicates that the gas production performance is dependent on the heat injection rate and the well spacing of the 5S system. OPEN ACCESSEnergies 2015, 8 10797

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Section: Comparison Of the 5s And 2s Systemsmentioning

confidence: 99%

Assessment of Gas Production Potential from Hydrate Reservoir in Qilian Mountain Permafrost Using Five-Spot Horizontal Well System

2015

Energies

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“…As the sensible heat consumption of the system is the main source for hydrate dissociation under sharp depressurization in the initial exploitation period ( Figure 12 a), a small quantity of ice is formed near the production wells. The transformation of aqueous water into solid ice could provide a certain amount of latent heat for promoting hydrate dissociation [ 39 ]. Figure 12 b shows that the ice transition phenomenon becomes more severe before the injected hot water can be effectively transferred to these zones.…”

Section: Resultsmentioning

confidence: 99%

Numerical Investigation into the Gas Production from Hydrate Deposit under Various Thermal Stimulation Modes in a Multi-Well System in Qilian Mountain

Yuan

Zhang

et al. 2021

Entropy

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The primary objective of this study was to investigate the energy recovery performance of the permafrost hydrate deposit in the Qilian Mountain at site DK-2 using depressurization combined with thermal injection by the approach of numerical simulation. A novel multi-well system with five horizontal wells was applied for large-scale hydrate mining. The external heat is provided by means of water injection, wellbore heating, or the combinations of them through the central horizontal well, while the fluids are extracted outside from the other four production wells under constant depressurization conditions. The injected water can carry the heat into the hydrate deposit with a faster rate by thermal convection regime, while it also raises the local pressure obviously, which results in a strong prohibition effect on hydrate decomposition in the region close to the central well. The water production rate is always controllable when using the multi-well system. No gas seepage is observed in the reservoir due to the resistance of the undissociated hydrate. Compared with hot water injection, the electric heating combined with normal temperature water flooding basically shows the same promotion effect on gas recovery. Although the hydrate regeneration is more severe in the case of pure electric heating, the external heat can be more efficiently assimilated by gas hydrate, and the efficiency of gas production is best compared with the cases involving water injection. Thus, pure wellbore heating without water injection would be more suitable for hydrate development in deposits characterized by low-permeability conditions.

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“…The interdependent physical and chemical processes of heat and four substances, including hydrate, methane, water, and chemical inhibitors, can be described by this code in four kinds of states (i.e., aqueous liquid, gas, hydrate, and ice). Confidence in the adoption of this code for the modeling and forecasting of methane hydrate phase transition properties grows with successful experimental validations in various laboratory-scale hydrate deposits [ 15 , 16 , 22 , 28 ]. However, the irreversibilities during hydrate development have not been considered in this code due to the absence of a reliable entropy production model.…”

Section: Experimental and Numerical Simulationsmentioning

confidence: 99%

“…For the sake of efficient energy recovery from gas hydrates, several solutions have been suggested based on the principle of destructing the stability situations of NGH systems for fluid extraction [ 15 ], including the depressurization [ 16 , 17 , 18 , 19 ], the thermal stimulation [ 20 , 21 , 22 ], the inhibitor injection [ 23 , 24 , 25 ], and the gas exchange method [ 26 , 27 ]. Due to the technical simplicity and the low external energy demand of the depressurization method, it is widely recognized as the simplest and most promising strategy for hydrate exploitation [ 28 , 29 ]. The enthalpy of hydrate decomposition under depressurization is primarily originated from two aspects: the continuous heat supply from the external environment and the sensible heat of the hydrate deposit [ 16 , 30 ].…”

Section: Introductionmentioning

confidence: 99%

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

Wei

Wan

et al. 2020

Entropy

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The purpose of this study is to analyze the dynamic properties of gas hydrate development from a large hydrate simulator through numerical simulation. A mathematical model of heat transfer and entropy production of methane hydrate dissociation by depressurization has been established, and the change behaviors of various heat flows and entropy generations have been evaluated. Simulation results show that most of the heat supplied from outside is assimilated by methane hydrate. The energy loss caused by the fluid production is insignificant in comparison to the heat assimilation of the hydrate reservoir. The entropy generation of gas hydrate can be considered as the entropy flow from the ambient environment to the hydrate particles, and it is favorable from the perspective of efficient hydrate exploitation. On the contrary, the undesirable entropy generations of water, gas and quartz sand are induced by the irreversible heat conduction and thermal convection under notable temperature gradient in the deposit. Although lower production pressure will lead to larger entropy production of the whole system, the irreversible energy loss is always extremely limited when compared with the amount of thermal energy utilized by methane hydrate. The production pressure should be set as low as possible for the purpose of enhancing exploitation efficiency, as the entropy production rate is not sensitive to the energy recovery rate under depressurization.

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Numerical analysis of methane hydrate decomposition experiments by depressurization around freezing point in porous media

Cited by 60 publications

References 34 publications

Assessment of Gas Production Potential from Hydrate Reservoir in Qilian Mountain Permafrost Using Five-Spot Horizontal Well System

Assessment of Gas Production Potential from Hydrate Reservoir in Qilian Mountain Permafrost Using Five-Spot Horizontal Well System

Numerical Investigation into the Gas Production from Hydrate Deposit under Various Thermal Stimulation Modes in a Multi-Well System in Qilian Mountain

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

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