scholarly journals Seismic Expression of Polygonal Faults and Its Impact on Fluid Flow Migration for Gas Hydrates Formation in Deep Water of the South China Sea

2011 ◽  
Vol 2011 ◽  
pp. 1-7
Author(s):  
Duanxin Chen ◽  
Shiguo Wu ◽  
Xiujuan Wang ◽  
Fuliang Lv

Polygonal faults were identified from three-dimensional (3D) seismic data in the middle-late Miocene marine sequences of the South China Sea. Polygonal faults in the study area are normal faults with fault lengths ranging from 100 to 1500 m, fault spaces ranging from 40 to 800 m, and throws ranging from 10 to 40 m. Gas hydrate was inferred from the seismic polarity, the reflection strength, and the temperature-pressure equilibrium computation results. Gas hydrates located in the sediments above the polygonal faults layer. Polygonal faults can act as pathways for the migration of fluid flow, which can supply hydrocarbons for the formation of gas hydrates.

2019 ◽  
Vol 124 (12) ◽  
pp. 8949-8968 ◽  
Author(s):  
Zhigang Lai ◽  
Guangzhen Jin ◽  
Yongmao Huang ◽  
Haiyun Chen ◽  
Xiaodong Shang ◽  
...  

2012 ◽  
Vol 307-310 ◽  
pp. 22-27 ◽  
Author(s):  
Changling Liu ◽  
Yuguang Ye ◽  
Qingguo Meng ◽  
Xingliang He ◽  
Hailong Lu ◽  
...  

2009 ◽  
Vol 66 (2) ◽  
pp. 420-431 ◽  
Author(s):  
Guimei Liu ◽  
Fei Chai

Abstract Liu, G., and Chai, F. 2009. Seasonal and interannual variability of primary and export production in the South China Sea: a three-dimensional physical–biogeochemical model study. – ICES Journal of Marine Science, 66: 420–431. To investigate the seasonal and interannual variations in biological productivity in the South China Sea (SCS), a Pacific basin-wide physical–biogeochemical model has been developed and used to estimate the biological productivity and export flux in the SCS. The Pacific circulation model, based on the Regional Ocean Model Systems (ROMS), is forced with daily air–sea fluxes derived from the NCEP (National Centers for Environmental Prediction) reanalysis between 1990 and 2004. The biogeochemical processes are simulated with a carbon, Si(OH)4, and nitrogen ecosystem (CoSiNE) model consisting of silicate, nitrate, ammonium, two phytoplankton groups (small phytoplankton and large phytoplankton), two zooplankton grazers (small micrograzers and large mesozooplankton), and two detritus pools. The ROMS–CoSiNE model favourably reproduces many of the observed features, such as Chl a, nutrients, and primary production (PP) in the SCS. The modelled depth-integrated PP over the euphotic zone (0–125 m) varies seasonally, with the highest value of 386 mg C m−2 d−1 during winter and the lowest value of 156 mg C m−2 d−1 during early summer. The annual mean value is 196 mg C m−2 d−1. The model-integrated annual mean new production (uptake of nitrate), in carbon units, is 64.4 mg C m−2 d−1, which yields an f-ratio of 0.33 for the entire SCS. The modelled export ratio (e-ratio: the ratio of export to PP) is 0.24 for the basin-wide SCS. The year-to-year variation of biological productivity in the SCS is weaker than the seasonal variation. The large phytoplankton group tends to dominate over the smaller phytoplankton group, and likely plays an important role in determining the interannual variability of primary and new production.


Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Jiangong Wei ◽  
Tingting Wu ◽  
Xiuli Feng ◽  
Jinqiang Liang ◽  
Wenjing Li ◽  
...  

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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