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

Li, Bo; Wei, Wen-Na; Wan, Qing-Cui; Peng, Kang

doi:10.3390/e22111212

Cited by 16 publications

(12 citation statements)

References 46 publications

(71 reference statements)

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“…The guest gases, such as methane molecules, are trapped in the water cavities at a low temperature and high pressure. − With the increasing demand of oil and nature gas resources, there is an urgent need to search for an alternative energy. Nature gas hydrates (NGHs) found in permafrost and deep ocean sediments are of significant potential due to their enormous reserves. − Different exploitive methods of nature gas hydrate from hydrate deposits have been proposed, namely, depressurization, − thermal stimulation, , as well as thermodynamic inhibitor injection. , The depressurization method is considered the most promising in terms of economic efficiency. , …”

Section: Introductionmentioning

confidence: 99%

“…4−6 Different exploitive methods of nature gas hydrate from hydrate deposits have been proposed, namely, depressurization, 7−9 thermal stimulation, 10,11 as well as thermodynamic inhibitor injection. 12,13 The depressurization method is considered the most promising in terms of economic efficiency. 14,15 The deposits of methane hydrate are generally divided into three classes, Class I (with underling free gas), Class II (with underling free-water), and Class III (single hydrate zone), 16,17 as shown in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

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Enhanced Gas Production from Hydrate Reservoirs with Underlying Water Layer

Shi

et al. 2021

Energy Fuels

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The recovery of natural gas from a marine hydrate reservoir is a complicated geological process, involving heat and mass transfer inside hydrate-bearing sediments as well between the overburden and underlying layers. Yet, most attention has been paid merely to the evolution of the hydrate reservoir itself. The idea has been proposed to consider as a whole the hydrate layer together with the overburden and underlying layers. In this work, the enhanced gas production behavior from the hydrate reservoir with an underlying water layer was specifically studied. It is found that the initial pressure propagation from the hydrate layer to the free water layer was very difficult; this thereby dominated the early stage of hydrate dissociation. The following dissociation of hydrate was majorly controlled by the heat supply from the sensible heat of the water layer and the resulting temperature distribution. A stepwise depressurization could significantly help enable a stable production rate, and the accumulative water yield depended strongly on the overall pressure drop, regardless of the process of depressurizing. Injecting heat was limited by the low efficiency of horizontal heat transfer resulting from the long distance and low thermal conductivity. The results are helpful in terms of providing guidance to field tests where there is commonly an underlying water layer and water production is frequently encountered.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Enhanced Gas Production from Hydrate Reservoirs with Underlying Water Layer

Shi

et al. 2021

Energy Fuels

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“…Yang et al [92] studied the heat transfer process and EGR of the two-layer porous media tube, and analyzed the local EGR under different parameters. Li et al [93] simulated the decomposition process of methane hydrate and analyzed the heat transfer characteristics and entropy generation under different pressure conditions. Under the constraint of fixed hydrogen PR, the EGRM was taken as the objective to optimize the HI decomposition reaction process, and the ultimate goal was to reduce the irreversibility of the reaction process and reduce the energy quality loss.…”

Section: Introductionmentioning

confidence: 99%

Minimization of Entropy Generation Rate in Hydrogen Iodide Decomposition Reactor Heated by High-Temperature Helium

Kong

Chen

Xia

et al. 2021

Entropy

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The thermochemical sulfur-iodine cycle is a potential method for hydrogen production, and the hydrogen iodide (HI) decomposition is the key step to determine the efficiency of hydrogen production in the cycle. To further reduce the irreversibility of various transmission processes in the HI decomposition reaction, a one-dimensional plug flow model of HI decomposition tubular reactor is established, and performance optimization with entropy generate rate minimization (EGRM) in the decomposition reaction system as an optimization goal based on finite-time thermodynamics is carried out. The reference reactor is heated counter-currently by high-temperature helium gas, the optimal reactor and the modified reactor are designed based on the reference reactor design parameters. With the EGRM as the optimization goal, the optimal control method is used to solve the optimal configuration of the reactor under the condition that both the reactant inlet state and hydrogen production rate are fixed, and the optimal value of total EGR in the reactor is reduced by 13.3% compared with the reference value. The reference reactor is improved on the basis of the total EGR in the optimal reactor, two modified reactors with increased length are designed under the condition of changing the helium inlet state. The total EGR of the two modified reactors are the same as that of the optimal reactor, which are realized by decreasing the helium inlet temperature and helium inlet flow rate, respectively. The results show that the EGR of heat transfer accounts for a large proportion, and the decrease of total EGR is mainly caused by reducing heat transfer irreversibility. The local total EGR of the optimal reactor distribution is more uniform, which approximately confirms the principle of equipartition of entropy production. The EGR distributions of the modified reactors are similar to that of the reference reactor, but the reactor length increases significantly, bringing a relatively large pressure drop. The research results have certain guiding significance to the optimum design of HI decomposition reactors.

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“…Because the occurrence environment of hydrate (high pressure and low temperature) is different from the conventional petroleum geology environment, once the balance is being destroyed, the gas hydrates become instable and decompose [18,19]. Moreover, it should be noted that ice and hydrate in the permafrost maintain the stability of the skeleton under the condition of perennial low temperature [20]. The original balance of permafrost reservoir will be broken by operation of the drilling, well completion, well cementation process, and production, like operation fluids will increase the temperature of reservoirs and melt the ice skeleton [19,[21][22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Thermal Diffusion Characteristics in Permafrost during the Exploitation of Gas Hydrate

et al. 2021

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Methane hydrate is the vast potential resources of natural gas in the permafrost and marine areas. Due to the occurrence of phase transition, the gas hydrate is dissociated into gas and water and absorbs lots of heat. The incomprehensive knowledge of endothermic reaction in permafrost sediments still restricted the production efficiency of hydrate commercial development. This endothermic reaction leads to a complex thermal diffusion in permafrost, which directly influences the phase transition in turn. In this research, the heat during the exploitation is transferred in two forms (specific heat and latent heat). Besides, the melting point is not constant but depends on the pore size of the reservoir rock. According to these features, a thermal diffusion model with phase transition is established. To calculate the governing equation, the pore size distribution is obtained by using the nuclear magnetic resonance (NMR) method. The heating tests are conducted and simulated to calibrate the coefficient (i.e., transverse surface relaxivity) of NMR. Then, the temperature field evolution of the hydrate reservoir during the exploitation is simulated by using the calibrated values. The results show that the temperature curves have a typical plateau related to the pore size distribution, which is effective to obtain the surface relaxivity. The heat transfer is remarkably limited by the endothermic effect of the phase transition. The hydrate recovery efficiency may depend largely on the heating capacity of the engineering operation and the rate of gas production. Compared to the conventional petroleum industry, it is significant to control the maximum temperature and temperature distribution in engineering operations during hydrate development. This research on the temperature behavior during onshore permafrost hydrate production could provide the theoretical support to control heat behavior of offshore hydrate production.

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

Cited by 16 publications

References 46 publications

Enhanced Gas Production from Hydrate Reservoirs with Underlying Water Layer

Enhanced Gas Production from Hydrate Reservoirs with Underlying Water Layer

Minimization of Entropy Generation Rate in Hydrogen Iodide Decomposition Reactor Heated by High-Temperature Helium

Thermal Diffusion Characteristics in Permafrost during the Exploitation of Gas Hydrate

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