Seismic wavefi eld modeling in media with fl uid-fi lled fractures and surface topography
Lan Hai-Qiang1,2 and Zhang Zhong-Jie1
1. State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China.
2. Graduate School of Chinese Academy of Sciences, Beijing 100049, China.
Abstract：
We present a finite difference (FD) method for the simulation of seismic wave fields in fractured medium with an irregular (non-flat) free surface which is beneficial for interpreting exploration data acquired in mountainous regions. Fractures are introduced through the Coates-Schoenberg approach into the FD scheme which leads to local anisotropic properties of the media where fractures are embedded. To implement surface topography, we take advantage of the boundary-conforming grid and map a rectangular grid onto a curved one. We use a stable and explicit second-order accurate fi nite difference scheme to discretize the elastic wave equations (in a curvilinear coordinate system) in a 2D heterogeneous transversely isotropic medium with a horizontal axis of symmetry (HTI). Efficiency tests performed by different numerical experiments clearly illustrate the infl uence of an irregular free surface on seismic wave propagation in fractured media which may be significant to mountain seismic exploration. The tests also illustrate that the scattered waves induced by the tips of the fracture are re-scattered by the features of the free surface topography. The scattered waves provoked by the topography are re-scattered by the fractures, especially Rayleigh wave scattering whose amplitudes are much larger than others and making it very diffi cult to identify effective information from the fractures.
LAN Hai-Qiang,ZHANG Zhong-Jie. Seismic wavefi eld modeling in media with fl uid-fi lled fractures and surface topography[J]. APPLIED GEOPHYSICS, 2012, 9(3): 301-312.
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2012, Vol. 9 
