Multiples raytracing in 3D anisotropic TI media with a tetrahedron cell model
Li Xingwang1, Bai Chaoying1,2, Li Xiaoling3
1. College of Geology Engineering and Geomatics, Chang'an University, Xi'an, Shannxi 710054, China;
2. Institute of Computing Geophysics, Chang'an University, Xi'an, Shannxi 710054, China;
3. Patent Examination Cooperation Center of the Patent Office, SIPO, Zhengzhou, Henan 450000, China
Abstract：The current algorithms can only trace first arrivals and primary reflections (or conversions),but cannot well trace multiples.To overcome this problem,with a tetrahedron cell model we extend the function of multistage irregular shortest-path method into 3D anisotropic TTI media for tracking multiple arrivals composed of any kind of combinations of transmissions,conversions and reflections.The basic principle is that the 7 parameters (5 elastic parameters and 2 titled angles of symmetry axis) of TTI media sampled at the primary nodes are used to calculate the group velocity of three-mode (qP,qSV,and qSH) waves.The group velocity values at the secondary nodes are obtained by a linear interpolation function via the defined values at the primary nodes of the cell.Finally we conduct grid (or cell) wavefront expansion to trace multiple arrivals from one layer to the next.The calculation in the uniform anisotropic media indicates that the numerical result is coincided with the analytic solution,which verifies the accuracy of the methodology.Several simulation results show that the proposed method is able to efficiently approximate the undulated topography and velocity discontinuity,and suitable for any combination of multiple arrivals tracking in TTI media with any titled angle of symmetry axis and not subject to the strength (no weak anisotropic assumption) of anisotropic media.
李兴旺, 白超英, 李晓玲. 四面体单元剖分下三维各向异性TI介质中多次波射线追踪[J]. 石油地球物理勘探, 2017, 52(1): 48-55.
Li Xingwang, Bai Chaoying, Li Xiaoling. Multiples raytracing in 3D anisotropic TI media with a tetrahedron cell model. OGP, 2017, 52(1): 48-55.
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