Numerical simulations of depressurization‐induced gas production from hydrate reservoirs at site GMGS3‐W19 with different free gas saturations in the northern South China Sea

Mao, Peixiao; Wu, N.; Sun, Jiaxin; Ning, Fulong; Chen, Lin; Wan, Yizhao; Hu, Gaowei; Cao, Xinxin

doi:10.1002/ese3.903

Cited by 11 publications

(4 citation statements)

References 71 publications

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“…The initial conditions of the hydrate reservoir are determined according to the process described by Moridis et al , The top and bottom boundaries of the simulated domain (corresponding to the uppermost and lowermost grid block layers, respectively) are set as a constant pressure and temperature. , The geothermal gradient at this site is 0.0443 °C/m with a seabed temperature of 3.7 °C, and the pressure in the sediments is considered to follow a hydrostatic distribution. Then, the temperature and pressure of the boundary layers can be determined, where the pressure is calculated using the pressure, temperature, and salinity-adjusted water density .…”

Section: Methodsmentioning

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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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: Methodsmentioning

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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“…To assess the efficiency of gas production and energy loss in coproduction of NGH-SG reservoirs, we have established an evaluation panel for the gas−water ratio and yield-loss ratio under different reservoir conditions at 60 days and 3000 days of CP, as illustrated in Figure 12. The gas−water ratio (R GW = V G /V W ) is a critical indicator for evaluating gas production efficiency, 48 and a higher R GW signifies favorable economic feasibility of gas production. 40 During the development of NGH and SG, a unique phenomenon of cross-flow gas loss may occur.…”

Section: Evaluation Of the Energy Recovery Of Ngh-sg Reservoirsmentioning

confidence: 99%

Energy Recovery from Natural Gas Hydrate and Shallow Gas Reservoirs: Exploring the Impact of Interlayer Gas Cross-Flow Behaviors

Zhao,

Li,

Chen

et al. 2024

Energy Fuels

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The coproduction of natural gas hydrate (NGH) and shallow gas (SG) represents a promising pathway toward the commercialization of marine hydrate resources. However, there is still a gap in exploring the impact of interlayer gas cross-flow behaviors on the energy recovery from NGH-SG reservoirs and coproduction characteristics with different reservoir properties. In order to address the gap, we conducted numerical simulations to study the production characteristics and interlayer gas cross-flow behaviors based on an NGH-SG reservoir model. The results demonstrate that reservoir properties affect both gas production and interlayer gas cross-flow. Interlayer gas cross-flow during the production process reduces production efficiency. The increase in permeability of shallow gas layer (SGL) is more favorable to improve the gas yield of coproduction compared with the increase in permeability of hydrate-bearing layer (HBL) and thickness of interlayer. Higher HBL permeability improves the gas cross-flow, while increased SGL permeability accelerates gas cross-flow during the early stages of production. Nevertheless, the increase in interlayer thickness mitigates interlayer gas cross-flow. The low-pressure zone of the HBL under the depressurization effect of the wellbore during coproduction is more extensive than that of the SGL, leading to the formation of a large interlayer pressure difference between the two layers. The pressure difference serves as a decisive factor in determining the occurrence of gas cross-flow, in addition to gas permeability, which significantly influences cross-flow velocity. To assess the efficiency of gas production and energy loss during coproduction of NGH-SG reservoirs, we have established an evaluation panel based on the gas−water ratio and yield-loss ratio. Combined energy recovery efficiency and economic efficiency, high SGL permeability is more favorable for coproduction. The findings of this study significantly enhance our understanding of interlayer gas cross-flow behaviors during the development of multilayer reservoirs and provide valuable guidance for the efficient coproduction of NGH-SG reservoirs.

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“…Case 1-4 is selected as the control group, and its injection–production parameters (T i , P p , and P i are 90 °C, 6 MPa, and 18 MPa, respectively) are used in case 0. Mao et al and Moridis et al , set the thickness of the overlying layer as the distance from the upper boundary of the HBS to the seafloor (136.4 and 217 m, respectively), and the thicknesses of the underlying layer are 200 and 330 m, respectively. Their results determined that those thicknesses are enough to provide a reliable model of pressure and temperature distribution.…”

Section: Numerical Model and Simulation Schemementioning

confidence: 99%

Research on the Influence of Injection–Production Parameters on Challenging Natural Gas Hydrate Exploitation Using Depressurization Combined with Thermal Injection Stimulated by Hydraulic Fracturing

et al. 2021

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The development of low-permeability hydrate reservoirs is facing serious problems. Our previous studies determined that depressurization combined with hot water injection stimulated by hydraulic fracturing (D + Tiw + HF) development mode has an excellent production potential in low-permeability hydrate reservoirs. Based on these, this study further explored the influences of injection–production parameters including injection temperature (T i), injection pressure (P i), and production pressure (P p) on D + Tiw + HF through single-factor and multivariate sensitivity analysis. Results show that the influence of T i, P i, and P p on D + Tiw + HF was divided into two opposite stages by the water breakthrough of production wells (t wb). The hydrate decomposition rate and CH4 production rate increase linearly with the increase in T i and P i and decrease in P p before t wb; however, they decrease gradually with the increase in T i and P i and decrease in P p after t wb. The sensitivity ranges of cumulative CH4 production (V P) to P p, T i, and P i are (3, 4.5), (0, 1.5), and (0, 1) in the first year and (1, 5), (0.5, 3), and (1, 2) in the fifth year, respectively. The sensitivity ranges of the energy ratio (ER) to P p, T i, and P i are (−2, −1), (−6, 0), and (−2.5, −1.5) in the first year and (−1.5, −1), (−7, 0), and (−2, 1) in the fifth year, respectively. This determines that V P is most sensitive to Pp , and the ER is most sensitive to T i. Furthermore, the ER is more sensitive to smaller T i. The V P is more sensitive to smaller P p in the early development stage (1 year, before t wb), while it is more sensitive to lager P p in the later development stage (5 years, after t wb). As a result, an as low as possible P p, low T i, and higher P i is suggested in the early development stage, while low T i and higher P i are suggested in the later development stage, and too small P p is unnecessary.

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Numerical simulations of depressurization‐induced gas production from hydrate reservoirs at site GMGS3‐W19 with different free gas saturations in the northern South China Sea

Abstract: This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Cited by 11 publications

References 71 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

Energy Recovery from Natural Gas Hydrate and Shallow Gas Reservoirs: Exploring the Impact of Interlayer Gas Cross-Flow Behaviors

Research on the Influence of Injection–Production Parameters on Challenging Natural Gas Hydrate Exploitation Using Depressurization Combined with Thermal Injection Stimulated by Hydraulic Fracturing

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