Geological Guided Tomography Inversion Based on Fault Constraint and Its Application

• Published in: Journal of Ocean University of China Vol. 20; no. 6; pp. 1419 - 1430
• Main Authors: Li, Sanfu, Zhang, Xiaobo, Dan, Zhiwei, Sun, Bo, Song, Peng, Sun, Leiming, Fang, Zhongyu, Li, Lie
• Format: Journal Article
• Language: English
• Published: Heidelberg Science Press 01.12.2021; Springer Nature B.V; National Deep Sea Center,Ministry of Natural Resources,Qingdao 266237,China%College of Marine Geosciences,Ocean University of China,Qingdao 266100,China%Zhanjiang Branch of CNOOC Ltd.,Zhanjiang 524057,China; Data Processing Company,Geophysical-COSL,Zhanjiang 524057,China%Laboratory for Marine Geology and Environment,Pilot National Laboratory for Marine Science and Technology(Qingdao),Qingdao 266061,China; College of Ocean Science and Engineering,Shandong University of Science and Technology,Qingdao 266590,China; College of Marine Geosciences,Ocean University of China,Qingdao 266100,China
• Subjects: Anisotropy; Basins; Cenozoic; Constraints; Distortion; Earth and Environmental Science; Earth Sciences; Earthquakes; Geological structures; Geology; Imaging techniques; Mesozoic; Meteorology; Ocean basins; Oceanography; Offshore; Ray paths; Regularization; Reservoirs; Seismic activity; Seismic analysis; Seismic profiles; Shadows; Tomography; Velocity; South China Sea; fault shadow phenomenon; geological guidance-constrained tomography; fault block reservoir; pre-stack depth migration; regularization
• ISSN: 1672-5182; 1993-5021; 1672-5174
• DOI: 10.1007/s11802-021-4667-6

Fault block reservoirs are one of the main types of hydrocarbon reservoirs found in offshore basins, and they are widely distributed within the Mesozoic and Cenozoic basins of the northern South China Sea. Conventional seismic profiles of complex fault areas often contain obvious fragmentation and distortion of seismic events that is corresponding to geological structure under the fault. This phenomenon is known as a fault shadow; it occurs in relation to rapid changes in velocity near the fault that deviate the ray path of waves, and it seriously affects the ability to determine the geological structure and subsequently evaluate the reserves of fault reservoirs. In the current conventional tomography inversion method, the velocity model is over-smoothed, which results in distortion of the reflection layer under the fault. Based on the velocity tomography inversion of imaging gathers method and the concept of regularization, this paper first introduces the anisotropy Gauss regularization operator. A high-resolution tomography inversion method is then developed, and the fault-controlled geological guidance is constrained. This technology is then applied to a complex fault block reservoir basin in the South China Sea, and the results show that it can significantly solve the problem of fault shadow imaging and determine the geological structures in the target area. The newly developed method thus has very good application prospects.