Traveltime computation and OBN seismic record simulation for rugged seafloor in VTI medium

ABSTRACT

To improve the computational accuracy of seismic traveltime for complex structures in inhomogeneous media, a mesh generation method that is adaptive to a rugged seafloor or interface is presented. A hybrid mesh discrete velocity model consisting of conventional rectangular mesh and irregular quadrilateral mesh is also proposed. The local traveltime equations for the hybrid mesh are derived from the linear traveltime interpolation (LTI) method and are shown to be stable. The relationship between the group velocity and group angle is converted into that between group velocity and interpolated point coordinates, extending the LTI ray tracing algorithm to multiwave simulation in vertical transversely isotropic (VTI) medium by multi-stage partitioning. Computations of the first arrival, reflection, multiple reflection, multiple transmission conversion, and multiple reflection conversion seismic waves in the VTI medium with rugged seafloor and complex structural interfaces are realised. The results show that the proposed method can adapt to the rugged seafloor and velocity interfaces of complex structures, resulting in higher computational accuracy of the traveltime and ray paths for ocean bottom node (OBN) seismic wave simulation. The accuracy of the proposed method is verified by comparison with the finite-difference method. This method will be useful for modelling of seismic waves, wavefield identification, and study of seismic wave propagation in OBN seismic observations.

KEYWORDS:

• Seafloor
• anisotropy
• linear
• traveltime
• interpolation
• ray tracing

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was jointly supported by the National Natural Science Foundation of China (Researches on Seismic Wavefield Simulation and Converted Wave Imaging Methods for the Ocean Bottom Nodes with Grant No. 41874123) and the Fundamental Research Funds for the Central Universities (Geophysical Detection Technology for Highway Geological Disasters in Complex Mountainous Area with Grant No. 300102268401).