Numerical simulation on gas production from hydrate reservoir at the 1st offshore test site in the eastern Nankai Trough

Sun, Jiaxin; Ning, Fulong; Zhang, Ling; Liu, Tianle; Peng, Li; Liu, Zhichao; Li, Chenglong; Jiang, Guosheng

doi:10.1016/j.jngse.2016.01.036

Cited by 111 publications

(48 citation statements)

References 20 publications

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“…Because the radius distance of 1000 m can effectively avoid the boundary effects in 6-day production test, there is no flow of fluids and heat through the lateral boundary. The top of the silt-dominant zone and the bottom of the water-bearing zone are designed as constant temperature and pressure boundaries [17]. For simulation of the varied depressurization processes (Section 3.5), the time-independent Dirichlet boundary (e.g., constant pressure) conditions are applied to the production well.…”

Section: Model Geometry Boundaries and Spatial Discretizationmentioning

confidence: 99%

“…The initial reservoir pressure was assigned in line with the hydrostatic pressure, which was computed according to the water depth and a pressureadjusted saline water density [7,17]. The initial temperature was specified to be 4 ∘ C at the seafloor [11,17,23].…”

Section: Initial Conditionsmentioning

confidence: 99%

“…The initial temperature was specified to be 4 ∘ C at the seafloor [11,17,23]. The temperature profile was assigned to vary linearly as a function of depth with a geothermal gradient of 0.03 ∘ C/m.…”

Section: Initial Conditionsmentioning

confidence: 99%

“…Table 1 presents the main modeling parameters and physical properties for the AT1 site sediments at the Eastern Nankai Trough. These were based on the geophysical well logs and core samples analyses from published papers [4,17,22,23,27,28]. The permeability and porosity are based on the logging data of AT1-MC and the pressure core data of AT1-C as shown in Figure 3.…”

Section: Initial Conditionsmentioning

confidence: 99%

“…They indicated that the method combining depressurization and thermal stimulation can improve the hydrate production effectively. Based on the latest geological data in the Eastern Nankai Trough, the longterm production behavior was investigated by Sun et al [17] and Konno et al [4]. Both of their results indicated that the gas production rate is expected to increase with time and the simulated water recovery rate cannot match field measured data.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Multiphase Flow Behavior of Layered Methane Hydrate Reservoir Induced by Gas Production

Yuan¹,

Xu²,

Xin³

et al. 2017

Geofluids

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Gas hydrates are expected to be a potential energy resource with extensive distribution in the permafrost and in deep ocean sediments. The marine gas hydrate drilling explorations at the Eastern Nankai Trough of Japan revealed the variable distribution of hydrate deposits. Gas hydrate reservoirs are composed of alternating beds of sand and clay, with various conditions of permeability, porosity, and hydrate saturation. This study looks into the multiphase flow behaviors of layered methane hydrate reservoirs induced by gas production. Firstly, a history matching model by incorporating the available geological data at the test site of the Eastern Nankai Trough, which considers the layered heterogeneous structure of hydrate saturation, permeability, and porosity simultaneously, was constructed to investigate the production characteristics from layered hydrate reservoirs. Based on the validated model, the effects of the placement of production interval on production performance were investigated. The modeling results indicate that the dissociation zone is strongly affected by the vertical reservoir's heterogeneous structure and shows a unique dissociation front. The beneficial production interval scheme should consider the reservoir conditions with high permeability and high hydrate saturation. Consequently, the identification of the favorable hydrate deposits is significantly important to realize commercial production in the future.

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Section: Model Geometry Boundaries and Spatial Discretizationmentioning

confidence: 99%

Section: Initial Conditionsmentioning

confidence: 99%

Section: Initial Conditionsmentioning

confidence: 99%

Section: Initial Conditionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Multiphase Flow Behavior of Layered Methane Hydrate Reservoir Induced by Gas Production

Yuan¹,

Xu²,

Xin³

et al. 2017

Geofluids

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Gas production from a silty hydrate reservoir in the South China Sea using hydraulic fracturing: A numerical simulation

Sun

Ning

Liu

et al. 2019

Energy Science & Engineering

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108

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The low permeability of silty hydrate reservoirs in the South China Sea is a critical issue that threatens safe, efficient, and long‐term gas production from these reservoirs. Hydraulic fracturing is a potentially promising stimulation technology for such low‐permeability reservoirs. Here, we assess the gas production potential of a depressurization horizontal well that is assisted by the hydraulic fracturing using numerical simulation according to field data at site SH2 in this area. In addition, the number of horizontal wells drilled is discussed if commercial production is to be performed at this site. The results show that the production potential can be significantly stimulated at the early production stage by adopting hydraulic fracturing in this reservoir due to a better depressurization effect. However, the increase in gas recovery gradually decreases with the continuous dissociation of gas hydrates, and the evolution trend is similar to that in a reservoir without stimulation during later periods of gas production because the dissociation front gradually moves away from the fractures. From the perspective of production potential, using a horizontal well scheme assisted by the hydraulic fracturing technology for gas recovery from a hydrate deposit can sharply reduce the number of operation wells, shorten the drilling operation time, and boost the economic efficiency. The horizontal well scheme may be an effective way to increase the gas yield if the application of quickly deployed horizontal wells and hydraulic fracturing techniques in such hydrate reservoirs greatly increases in the near future.

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Effect of permeability anisotropy on depressurization‐induced gas production from hydrate reservoirs in the South China Sea

Mao

Sun

Ning

et al. 2020

Energy Science & Engineering

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The permeability anisotropy (ie, horizontal, kr, to vertical, kz, permeability ratio) of gas hydrate reservoirs may be a significant factor that affects hydrate dissociation and gas production. Here, site SH2, a candidate for field testing comprising a clayey silt gas hydrate reservoir in the Shenhu area in the South China Sea, was chosen to investigate the effect of permeability anisotropy on gas production behavior through numerical simulations. The spatial distribution of physical fields (ie, pressure, temperature, and saturation) and the evolution of gas and water recovery are comparatively analyzed. The simulation results show that permeability anisotropy has a significant impact on gas extraction, especially when the horizontal permeability is higher than the vertical one. The sensitivity analyses indicate that permeability anisotropy in both medium‐permeability (10‐100 mD) and low‐permeability (1‐10 mD) sediments are conducive to hydrate dissociation and that a higher horizontal permeability is more favorable for gas production. Comparatively, permeability anisotropy in low‐permeability sediments is not beneficial for improving production efficiency. In addition, our work also suggests that heterogeneous hydrate saturation in a reservoir‐scale model should be employed in future predictions because the gas production potential will be overestimated in a homogeneous reservoir under the same conditions. These findings contribute to a clear understanding of the influence of reservoir properties on gas hydrate dissociation processes and provide a reference for future field trials and commercial production.

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Numerical simulation on gas production from hydrate reservoir at the 1st offshore test site in the eastern Nankai Trough

Cited by 111 publications

References 20 publications

Multiphase Flow Behavior of Layered Methane Hydrate Reservoir Induced by Gas Production

Multiphase Flow Behavior of Layered Methane Hydrate Reservoir Induced by Gas Production

Gas production from a silty hydrate reservoir in the South China Sea using hydraulic fracturing: A numerical simulation

Effect of permeability anisotropy on depressurization‐induced gas production from hydrate reservoirs in the South China Sea

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