Methane Hydrate in Marine Sands: Its Reservoir Properties, Gas Production Behaviors, and Enhanced Recovery Methods

Konno, Yoshihiro; Nagao, Jiro

doi:10.1627/jpi.64.113

Cited by 10 publications

(8 citation statements)

References 49 publications

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“…The Tokyo model is expressed as where k d , k d0 , S h , and N are effective permeability, absolute permeability, hydrate saturation, and permeability reduction index, respectively . The permeability reduction index N is an empirical parameter and ranges from approximately 2 to 7 . Effective permeability to water and gas is expressed by multiplying k d by relative permeability to water and gas, respectively.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, enhanced recovery or well stimulating methods, such as hydraulic fracturing, will be necessary to mitigate gas production stagnation and ensure stable production . These attempts increase the viability of the commercialization of MH development …”

Section: Discussionmentioning

confidence: 99%

“…19 The permeability reduction index N is an empirical parameter and ranges from approximately 2 to 7. 20 Effective permeability to water and gas is expressed by multiplying k d by relative permeability to water and gas, respectively. The Tokyo model and the other proposed models presuppose that effective permeability increases with hydrate dissociation.…”

Section: ■ Discussionmentioning

confidence: 99%

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Influence of Flow Properties on Gas Productivity in Gas-Hydrate Reservoirs: What Can We Learn from Offshore Production Tests?

et al. 2021

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Gas hydrates are expected to be an energy resource in this century. Many countries, such as the United States, China, India, and Japan, have explored potential reservoirs and promising production methods. During the past decade, Japan has conducted the world’s first offshore production test in the eastern Nankai Trough, followed by China in the South China Sea. These offshore production tests have demonstrated that gas can be produced continuously from hydrate-bearing sand or silt-rich sediments. However, production tests in the eastern Nankai Trough have shown that gas production declines for a few days and then remains constant at a constant pressure in the bottom hole for at least a period of 4 days. This result is different from predicted behaviors by numerical simulations, showing a gradual increase in the gas production rate with time. The discrepancy between actual data and numerical simulations indicates that numerical simulators overestimate the response as a result of the lack of a proper system description in the models. Numerical simulation can reproduce the tendency of gas production stagnation by considering hydrate reformation in the reservoir. However, hydrate reformation is not expected to occur during the early stages of tests. Recent experimental and numerical studies have shown that sediment compaction and particle crushing by high effective stress, migration of fines leading to the formation of a skin, and changes in relative permeability are induced by depressurization during gas production. These phenomena result in dynamic permeability changes that can lead to gas production stagnation in the early stages.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: ■ Discussionmentioning

confidence: 99%

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Influence of Flow Properties on Gas Productivity in Gas-Hydrate Reservoirs: What Can We Learn from Offshore Production Tests?

et al. 2021

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“…Hydraulic fracturing technologies have proved to be successful and efficient in the development of unconventional oil, gas in shale with artificially established fractures increases the contact area in the reservoir, and hydrocarbon flow diffusivity is consequently enhanced . As a result, many researchers have entertained the possibility of using hydraulic fracturing in hydrate-bearing sediments to improve gas productivity . Both Feng et al and Ma et al used the widely recognized Tough+Hydrate simulator to study the gas production efficiency of depressurization in hydraulic fractures in methane hydrate reservoirs.…”

Section: Introductionmentioning

confidence: 99%

“…15 As a result, many researchers have entertained the possibility of using hydraulic fracturing in hydrate-bearing sediments to improve gas productivity. 16 Both Feng et al 17 and Ma et al 18 used the widely recognized Tough+Hydrate simulator to study the gas production efficiency of depressurization in hydraulic fractures in methane hydrate reservoirs. Feng et al 17 concluded that although the initial gas productivity is enhanced, long-term cumulative gas production is not drastically improved, while Ma et al 18 emphasized that fracture length and horizontal well location jointly affected the enhanced ultimate recovery, and an increase in fracture length actually has no impact on gas production from the fracture.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of the Gas Production Efficiency and Induced Geomechanical Responses in Marine Methane Hydrate-Bearing Sediments Exploited by Depressurization through Hydraulic Fractures

Guo

Jin

et al. 2021

Energy Fuels

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Methane hydrates are a promising source of natural gas. Several field tests have validated the feasibility of gas production from marine methane hydrate-bearing sediments. However, sustained and commercial production has not been obtained due to limited gas production efficiency and production-induced damage to the mechanical properties in the sediments. This study investigates the gas production efficiency and the geomechanical responses in hydrate-bearing sediments developed by depressurization in hydraulic fractures. A numerical model for the simulation of coupled thermal–hydraulic–mechanical–chemical behaviors is described. The model considers three phases of water, gas, and hydrate in the sediments. Heat transport and the kinetics for hydrate dissociation are also taken into account. A Mohr–Coulomb criterion for marine methane hydrate-bearing reservoirs is employed to describe the shear failure and damaged rock strength caused by depressurization in hydraulic fractures. Then, a base case for a 750-day depressurization in a hydraulic fracture is presented. The spatial and temporal evolutions of the pore pressure, temperature, hydrate dissociation, principal stress, and shear failure are described. Parametric studies for reservoir permeability, depressurization pressure, and fracture number are also presented. The results indicate that early-stage gas rates are high, while they drop significantly with time. At late stages, shear failure is highly correlated with the reduced rock strength, and stress concentrations are obtained near fracture tips. The evolution of strength is correlated with hydrate dissociation as dissociated hydrates weaken the mechanical properties in sediments, which is also time dependent. Local stress concentrations are observed around fracture tips as well. Higher reservoir permeabilities lead to greater early-stage production and lower late-stage production, indicating that the use of hydraulic fractures is preferable in low-permeability reservoirs. Also, increasing the hydraulic fracture number can improve the overall gas production efficiency, while the average gas production efficiency from individual fractures is decreased.

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Studies on micromorphology and permeability of hydrate-bearing porous media

Weng²,

Li³

et al. 2023

Fuel

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Methane Hydrate in Marine Sands: Its Reservoir Properties, Gas Production Behaviors, and Enhanced Recovery Methods

Cited by 10 publications

References 49 publications

Influence of Flow Properties on Gas Productivity in Gas-Hydrate Reservoirs: What Can We Learn from Offshore Production Tests?

Influence of Flow Properties on Gas Productivity in Gas-Hydrate Reservoirs: What Can We Learn from Offshore Production Tests?

Numerical Investigation of the Gas Production Efficiency and Induced Geomechanical Responses in Marine Methane Hydrate-Bearing Sediments Exploited by Depressurization through Hydraulic Fractures

Studies on micromorphology and permeability of hydrate-bearing porous media

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