Geological and geophysical features of and controls on occurrence and accumulation of gas hydrates in the first offshore gas-hydrate production test region in the Shenhu area, Northern South China Sea

Zhang, Wei; Liang, Jin; Lu, Jing; Su, Pibo; Lin, Lin; Huang, Wei; Guo, Yiqun; Deng, Wang-Qiu; Yang, Xiaoli; Wan, Zhifeng

doi:10.1016/j.marpetgeo.2019.104191

Cited by 121 publications

(68 citation statements)

References 73 publications

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“…Natural-gas hydrate deposits represent one of the largest methane reservoirs on earth [14,15]. Thus, it has been considered a potential energy resource, and intense studies are ongoing to both assess the amount of natural gas bound in these deposits and for the development of new technologies for future exploitation [16][17][18][19][20][21][22]. Natural-gas hydrates are very sensitive to changes in temperature, pressure and water chemistry (e.g., water salinity), and they are deemed to be a potential geohazard if one of these parameters evolves and triggers their destabilization [23][24][25][26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Methane Hydrate Formation and Dissociation in Sand Media: Effect of Water Saturation, Gas Flowrate and Particle Size

et al. 2020

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Assessing the influence of key parameters governing the formation of hydrates and determining the capacity of the latter to store gaseous molecules is needed to improve our understanding of the role of natural gas hydrates in the oceanic methane cycle. Such knowledge will also support the development of new industrial processes and technologies such as those related to thermal energy storage. In this study, high-pressure laboratory methane hydrate formation and dissociation experiments were carried out in a sandy matrix at a temperature around 276.65 K. Methane was continuously injected at constant flowrate to allow hydrate formation over the course of the injection step. The influence of water saturation, methane injection flowrate and particle size on hydrate formation kinetics and methane storage capacity were investigated. Six water saturations (10.8%, 21.6%, 33%, 43.9%, 55% and 66.3%), three gas flowrates (29, 58 and 78 mLn·min−1) and three classes of particle size (80–140, 315–450 and 80–450 µm) were tested, and the resulting data were tabulated. Overall, the measured induction time obtained at 53–57% water saturation has an average value of 58 ± 14 min minutes with clear discrepancies that express the stochastic nature of hydrate nucleation, and/or results from the heterogeneity in the porosity and permeability fields of the sandy core due to heterogeneous particles. Besides, the results emphasize a clear link between the gas injection flowrate and the induction time whatever the particle size and water saturation. An increase in the gas flowrate from 29 to 78 mLn·min−1 is accompanied by a decrease in the induction time up to ~100 min (i.e., ~77% decrease). However, such clear behaviour is less conspicuous when varying either the particle size or the water saturation. Likewise, the volume of hydrate-bound methane increases with increasing water saturation. This study showed that water is not totally converted into hydrates and most of the calculated conversion ratios are around 74–84%, with the lowest value of 49.5% conversion at 54% of water saturation and the highest values of 97.8% for the lowest water saturation (10.8%). Comparison with similar experiments in the literature is also carried out herein.

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Section: Introductionmentioning

confidence: 99%

Methane Hydrate Formation and Dissociation in Sand Media: Effect of Water Saturation, Gas Flowrate and Particle Size

et al. 2020

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“…The clay content ranges from 17.2% to 44.2%, and the silt content ranges from 55.6% to 80.1%. 1 In addition, the underlying free gas layer is distributed at 174.4-193.9 mbsf with relatively low absolute permeability (average 2 mD). This reservoir is a typical Class 1 hydrate reservoir.…”

Section: Target Reservoir Conditions Model Construction and Domain Discretizationmentioning

confidence: 99%

“…Natural gas hydrate (NGH) is regarded as one of the most promising alternative energy resources that is widely distributed in permafrost zones and oceanic sediments. The NGH reservoirs are generally divided into four classes: Class 1 (the free gas layer above which the hydrate-bearing layer exists), 1 Class 2 (hydrate formation overlies a mobile water zone), 2 Class 3 (only one hydrate formation without any underlying zone of mobile fluids), 3,4 and Class 4 (reservoirs with low hydrate saturation and unconfined geological strata near the seafloor, hydrates in fractures, etc). 5 The percentages of the above four types of reservoirs in nature are expected to be 14%, 5%, 6%, and 75%, respectively.…”

Section: Introductionmentioning

confidence: 99%

“…20,21 Later, several Class 1 hydrate accumulations were discovered during the second and third hydrate expeditions at sites W17 and W19. 1 Based on these field studies, in 2017, the first offshore gas hydrate production trial was performed successfully in a clayey silt Class 1 hydrate reservoir, with a total gas production of 3.09 × 10 5 m 3 . 15,22 However, the gas recovery rate (average 5000 m 3 /d) is still far from the commercial production level.…”

Section: Introductionmentioning

confidence: 99%

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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

Mao

Sun

et al. 2021

Energy Science & Engineering

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“…Six gas hydrate drilling expeditions [31][32][33][34][35][36][37] and two production tests were successfully conducted by the Guangzhou Marine Geological Survey between 2007 and 2019 on the northern continental slope of the South China Sea [38]; however, the geomechanical properties and permeability of the gas hydrate-bearing sediments have not been publically reported. In this study, we determined the physical properties of the hydrate-bearing pressure core sediments obtained from the Pearl River Mouth Basin in the South China Sea in 2013.…”

Section: Introductionmentioning

confidence: 99%

Physical Properties of Gas Hydrate-Bearing Pressure Core Sediments in the South China Sea

Wei

Feng

et al. 2021

Geofluids

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Gas hydrates are a potential future energy resource and are widely distributed in marine sediments and permafrost areas. The physical properties and mechanical behavior of gas hydrate-bearing sediments are of great significance to seafloor stability and platform safety. In 2013, a large number of pressure cores were recovered during China’s second gas hydrate drilling expedition in the South China Sea. In this study, we determined the gas hydrate distribution, saturation, physical properties, and mechanical behavior of the gas hydrate-bearing sediments by conducting Multi-Sensor Core Logger measurements and triaxial and permeability tests. Disseminated gas hydrates, gas hydrate veins, and gas hydrate slabs were observed in the sediments. The gas hydrate distribution and saturation are spatially heterogeneous, with gas hydrate saturations of 0%–55.3%. The peak deviatoric stress of the gas hydrate-bearing sediments is 0.14–1.62 MPa under a 0.15–2.3 MPa effective confining stress. The permeability is 0.006– 0.095 × 10 − 3 μ m 2 , and it decreases with increasing gas hydrate saturation and burial depth.

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Geological and geophysical features of and controls on occurrence and accumulation of gas hydrates in the first offshore gas-hydrate production test region in the Shenhu area, Northern South China Sea

Cited by 121 publications

References 73 publications

Methane Hydrate Formation and Dissociation in Sand Media: Effect of Water Saturation, Gas Flowrate and Particle Size

Methane Hydrate Formation and Dissociation in Sand Media: Effect of Water Saturation, Gas Flowrate and Particle Size

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

Physical Properties of Gas Hydrate-Bearing Pressure Core Sediments in the South China Sea

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