Application of horizontal well to gas production from a hydrate reservoir with free gas and high irreducible water

Shang, Siyuan; Gu, Lijuan; Zhan, Li; Qiu, Haijun; Lu, Hailong

doi:10.1016/j.jngse.2021.104102

Cited by 18 publications

(10 citation statements)

References 33 publications

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“…Correspondingly, the R GW of the latter is always greater than that of the former. Therefore, from the perspective of wellhead water production and the gas− liquid ratio, the presence of underlying free gas is conducive to the production of the hydrate reservoir, this is consistent with the results of Lu et al 30 3.2. Application of Hydraulic Fracturing.…”

Section: Resultsmentioning

confidence: 99%

“…Through experiments, Yang et al 29 found that the hydrate dissociation rate and the cumulative gas/water production are positively correlated with the pressure of the underlying free gas layer. Lu et al 30 indicated that the contribution of underlying free gas to production is mainly concentrated in the initial stage. Song et al 32 compared the production behaviors of hydrate reservoirs with excess gas and excess water using magnetic resonance imaging (MRI) technology.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Evaluation of Long-Term Depressurization Production of a Multilayer Gas Hydrate Reservoir and Its Hydraulic Fracturing Applications

Cai

Ding

et al. 2022

Energy Fuels

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In this study, a multilayer gas hydrate reservoir model was implemented based on the geological conditions of the Shenhu area in the South China Sea (SHCS) to predict the production performance of the reservoir during long-term depressurization. Hydraulic fracturing technology was introduced to boost production, and its positive/negative impact on the production behavior of the hydrate reservoir was evaluated. Results show that hydrate dissociation is severely constrained by pressure propagation and fluid flow in the low reservoir. During production, almost half of the wellhead gas production is from the dissolved gas in seawater and the free gas contained in sediments. Massive secondary hydrate forms and gathers in the hydrate layer I and near the interface of hydrate layers. Underlying free gas is conducive to reservoir production, in which the cumulative wellhead gas production can be increased by ∼59% compared to the reservoir lacking underlying free gas. On one hand, hydraulic fracturing can significantly promote hydrate dissociation and increase the capacity of production, especially for long-distance fracture implemented in the middle part of the hydrate layer. On the other hand, high permeability in the fractured zone also provides a convenient channel for water in the sedimentary layer. After hydraulic fracturing, the production efficiency of the reservoir is still low due to the involvement of more pore water. In future, the combination of hydraulic fracturing and other auxiliary means can be considered to develop hydrate reservoirs.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical Evaluation of Long-Term Depressurization Production of a Multilayer Gas Hydrate Reservoir and Its Hydraulic Fracturing Applications

Cai

Ding

et al. 2022

Energy Fuels

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“…No flow is assumed across the boundaries x = −100 m and x = 100 m, indicating that the domain is a closed system with a well spacing of 200 m in this direction. Following our previous study, 29 the key simulation parameters are summarized in Table 2.…”

Section: Methodsmentioning

confidence: 99%

“…The scope of this study is to investigate the feasibility and mechanism of gas production from a marine MH reservoir with a configuration of two horizontal wells by hot water injection combined with depressurization. Compared with a vertical well, a horizontal well is more favorable for hydrate dissociation and may be suitable for commercial gas production. − Therefore, a 2D Cartesian hydrate reservoir model that consists of multiple layers and two parallel horizontal wells is established. Through numerical simulation, the production performance and reservoir response of the MH reservoir are investigated under different production conditions.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of the Effect of Thermal Stimulation on Gas Production from Marine Hydrate Reservoirs

Shang

Zhan

et al. 2022

Energy Fuels

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The temperature of hydrate reservoirs will decrease in a gas production process because gas hydrate dissociation is endothermic, leading to a decrease in the gas production rate as sensible heat is exhausted. Heat supply should be an effective way to alleviate the effect of temperature decrease on the production rate, by thermal stimulation, such as hot water injection into a hydrate reservoir. However, the feasibility of thermal stimulation combined with depressurization is controversial. Hence, to investigate the effect of this combined strategy, gas production performance is studied by numerical simulation based on a 2D Cartesian hydrate reservoir model with a two parallel horizontal well configuration. One of the two horizontal wells, at the top of the hydrate-bearing layers, is for gas production, and the other at the bottom of the hydrate-bearing layers is for hot water injection. The influence of the injection rate, temperature of hot water, and permeability of hydrate-bearing layers on gas production is investigated. When only the hot water injection is applied, the released gas, which originates from the dissociation of hydrates around the injection well, tends to be trapped and forms hydrates again. When the production strategy of hot water injection combined with depressurization is engaged, the hydrate dissociation shows a depressurization-dominant feature, and the production is at a relatively high rate, but it seems the hot water injection is still a negative factor in gas production. Because the hot water injection will replenish reservoir pressure and increase the water production rate, the feasibility of depressurization will be compromised. Sensitivity analyses reveal that the increased permeability of hydratebearing layers can enhance gas production almost proportionally. It is also found that increasing the temperature of the injected hot water only has a very limited effect on gas production.

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“…As a result, further understanding of the interaction between the artificial fracture and the gas production process should be investigated through numerical and practical approaches. Furthermore, horizontal wells [49] and multi-well [50] configurations can be employed to enhance gas production rate to achieve commercial exploitation of hydrate reservoir.…”

Section: Effect Of Fracture Conductivity On Production Performancementioning

confidence: 99%

The Effects of the Length and Conductivity of Artificial Fracture on Gas Production from a Class 3 Hydrate Reservoir

Shang

2021

Energies

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Natural gas hydrate is considered as a potential energy resource. To develop technologies for the exploitation of natural gas hydrate, several field gas production tests have been carried out in permafrost and continental slope sediments. However, the gas production rates in these tests were still limited, and the low permeability of the hydrate-bearing sediments is identified as one of the crucial factors. Artificial fracturing is proposed to promote gas production rate by improving reservoir permeability. In this research, numerical studies about the effect of fracture length and fluid conductivity on production performance were carried out on an artificially fractured Class 3 hydrate reservoir (where the single hydrate zone is surrounded by an overlaying and underlying hydrate-free zone), in which the equivalent conductivity method was applied to depict the artificial fracture. The results show that artificial fracture can enhance gas production by offering an extra fluid flow channel for the migration of gas released from hydrate dissociation. The effect of fracture length on production is closely related to the time frame of production, and gas production improvement by enlarging the fracture length is observed after a certain production duration. Through the production process, secondary hydrate formation is absent in the fracture, and the high conductivity in the fracture is maintained. The results indicate that the increase in fracture conductivity has a limited effect on enhancing gas production.

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Application of horizontal well to gas production from a hydrate reservoir with free gas and high irreducible water

Cited by 18 publications

References 33 publications

Numerical Evaluation of Long-Term Depressurization Production of a Multilayer Gas Hydrate Reservoir and Its Hydraulic Fracturing Applications

Numerical Evaluation of Long-Term Depressurization Production of a Multilayer Gas Hydrate Reservoir and Its Hydraulic Fracturing Applications

Numerical Study of the Effect of Thermal Stimulation on Gas Production from Marine Hydrate Reservoirs

The Effects of the Length and Conductivity of Artificial Fracture on Gas Production from a Class 3 Hydrate Reservoir

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