Geophysical Signature of the Shallow Water Flow in the Deepwater Basin of the Northern South China Sea

• Published in: Journal of Ocean University of China Vol. 17; no. 4; pp. 791 - 798
• Main Authors: Zhang, Xiaohua, Sun, Yunbao, Wu, Shiguo, Dong, Dongdong
• Format: Journal Article
• Language: English
• Published: Heidelberg Science Press 01-08-2018; Springer Nature B.V; Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology,Qingdao 266071, China%Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology,Qingdao 266071, China; University of Chinese Academy of Sciences, Beijing 100049, China%Key Laboratory of Marine Hydrocarbon Resource and Geology, Qingdao Institute of Marine Geology,Qingdao 266071, China; Key Laboratory of Gas Hydrate, Ministry of Natural Resources, Qingdao Institute of Marine Geology,Qingdao 266071, China%Key Laboratory of Gas Hydrate, Ministry of Natural Resources, Qingdao Institute of Marine Geology,Qingdao 266071, China; College of Marine Geosciences, Ocean University of China, Qingao 266100, China; Institute of Deep-Sea Science and Engineering, Chinese Academy of Sciences, Sanya 572000, China; Hainan Key Laboratory of Marine Georesources and Prospecting, Sanya 572000, China
• Subjects: Computational fluid dynamics; Continental margins; Data processing; Deep sea drilling; Deep water; Deepwater drilling; Drilling; Earth and Environmental Science; Earth Sciences; Earthquake damage; Fluid flow; Foundation failure; Fracture mechanics; Gas bearings; Geological data; Geological hazards; Geophysics; Meteorology; Mounds; Ocean floor; Oceanography; Overpressure; Poisson's ratio; Sand; Sedimentation; Sediments; Seismic data; Shallow water; Water flow; South China Sea; South China Sea; geohazard; deepwater hydrocarbons; shallow water flow; pressure prediction
• ISSN: 1672-5182; 1993-5021; 1672-5174
• DOI: 10.1007/s11802-018-3487-9

Shallow water flow (SWF), a disastrous geohazard in the continental margin, has threatened deepwater drilling operations. Under overpressure conditions, continual flow delivering unconsolidated sands upward in the shallow layer below the seafloor may cause large and long-lasting uncontrolled flows; these flows may lead to control problems and cause well damage and foundation failure. Eruptions from over-pressured sands may result in seafloor craters, mounds, and cracks. Detailed studies of 2D/3D seismic data from a slope basin of the South China Sea (SCS) indicated the potential presence of SWF. It is commonly characterized by lower elastic impedance, a higher
Vp
/
Vs
ratio, and a higher Poisson’s ratio than that for the surrounding sediments. Analysis of geological data indicated the SWF zone originated from a deepwater channel system with gas bearing over-pressured fluid flow and a high sedimentation rate. We proposed a fluid flow model for SWF that clearly identifies its stress and pressure changes. The rupture of previous SWF zones caused the fluid flow that occurred in the Baiyun Sag of the northern SCS.