Production potential and stability of hydrate-bearing sediments at the site GMGS3-W19 in the South China Sea: A preliminary feasibility study

Sun, Jiaxin; Zhang, Ling; Ning, Fulong; Lei, Hongwu; Liu, Tianle; Hu, Gaowei; Lu, Hailong; Lu, Jing; Liu, Changling; Jiang, Guosheng; Liang, Jin; Wu, N.

doi:10.1016/j.marpetgeo.2017.05.037

Cited by 154 publications

(62 citation statements)

References 43 publications

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“…In this work, TOUGH + HYDRATE 62 software was employed to address this issue because the software was generally used to simulate gas recovery from hydrate reservoirs in marine and permafrost regions, 27,28,30,[63][64][65] The geomechanical response was not considered because the influence of effective stress variation on the sediment and fracture properties in GHBS at this site during depressurization is currently unclear, even though the coupled thermo-hydro-mechanical model was proposed and used to perform the coupling processes during drilling and gas recovery. 25,29,[66][67][68][69][70][71][72] However, the assigned permeability of fractures takes the influence of the effective stress into account. The latter means that the value adopted is the experimental measurement in other sediments after which the bottom hole pressure remains constant after initially decreasing (i.e., the assigned fracture permeability is measured at the corresponding effective confining pressure condition).…”

Section: Numerical Simulation Codementioning

confidence: 99%

“…Consequently, many investigations (eg, Refs. [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] have been performed recently, and numerical simulations have still focused on depressurization that is aimed at commercial production from potential target areas. In practice, depressurization has also been widely adopted in field trials in Mallik, 34 the eastern Nankai Trough, 35,36 and the South China Sea.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Numerical Simulation Codementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Self Cite

108

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“…Earlier studies had shown the validity of this approximation [8,49]. The composite thermal conductivity, relative permeability, and capillary pressure models are employed commonly in numerical simulations on gas production from HBS [1,4,[30][31][32]50]. The corresponding parameters for relative permeability and capillary pressure were determined from the field test data by Moridis and Reagan [51].…”

Section: Model Geometry and Spatial Discretizationmentioning

confidence: 99%

“…They indicated that the balance between gas production and reservoir stability is needed to be optimized. The further investigation about the geomechanical behaviors of the HBS induced by gas production indicated that the spatial evolution of the temperature, pore pressure, hydrate saturation, and gas saturation are the most relevant factors [1,[30][31][32][33][34][35].…”

Section: Introductionmentioning

confidence: 99%

“…They indicated that permeability, porosity, and initial hydrate saturation have significant effects on gas production performance. Recently, on the basis of the available geological data from site GMGS3-W19 [20], the geomechanical behaviors for gas production in this area have been conducted and reported by Sun et al [30]. They indicated that the balance between gas production and reservoir stability is needed to be optimized.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Formation Dip on Gas Production from Unconfined Marine Hydrate-Bearing Sediments through Depressurization

Yuan

Xia

et al. 2018

Geofluids

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The effects of geologic conditions and production methods on gas production from hydrate-bearing sediments (HBS) have been widely investigated. The reservoir was usually treated as horizontal distribution, whereas the sloping reservoir was not considered. In fact, most strata have gradients because of the effects of geological structure and diagenesis. In this study, based on currently available geological data from field measurements in Shenhu area of the South China Sea, the effects of formation dip on gas production were investigated through depressurization using a horizontal well. The modeling results indicate that the strategy of horizontal well is an effective production method from the unconfined Class 2 HBS. The predicted cumulative volume of methane produced at the 1000 m horizontal well was 4.51 × 10 7 ST m 3 over 5-year period. The hydrate dissociation behavior of sloping formation is sensitive to changes in the reservoir pressure. As in unconfined marine hydrate reservoir, the sloping formation is not conducive to free methane gas recovery, which results in more dissolved methane produced at the horizontal well. The obvious issue for this challenging target is relatively low exploitation efficiency of methane because of the recovery of very large volumes of water. Consequently, the development of the favorable well completion method to prevent water production is significantly important for realizing large scale hydrate exploitation in the 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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Production potential and stability of hydrate-bearing sediments at the site GMGS3-W19 in the South China Sea: A preliminary feasibility study

Cited by 154 publications

References 43 publications

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

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

Effects of Formation Dip on Gas Production from Unconfined Marine Hydrate-Bearing Sediments through Depressurization

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

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