Fractured subsurface formations with anisotropic backgrounds, such as in shale layers, can be effectively modeled as orthorhombic media in many cases. Extracting interval orthorhombic parameters from seismic data (surface or VSP) is, however, a non-unique and nonlinear problem. The extraction is further complicated by the presence of local extrema in the error functional that needs to be optimized. Such parameters, however, can help characterize the formations better, and hence it is necessary to develop a robust methodology for such parameter extraction. In this work, we developed an inversion scheme for obtaining interval orthorhombic parameters from VSP walkaway and walkaround direct P-wave travel time data. We combined a layer (3D planar/non-planar) based anisotropic ray tracer with a global optimization algorithm called Differential Evolution to estimate P-wave anisotropic parameters along with principal stress orientations. We further applied the developed algorithm to a field dataset and demonstrated that it can help obtain orthorhombic media parameters that could be potentially related to geology, in the presence of noise and suboptimal acquisition design.


Article metrics loading...

Loading full text...

Full text loading...


  1. Chapman, C.
    [2004] Fundamentals of seismic wave propagation. Cambridge University Press, Cambridge.
    [Google Scholar]
  2. Padhi, A. and Willis, M.
    [2015] VSP modeling and sensitivity analysis of travel times in layered orthorhombic media with general 3D horizons. SEG Technical Program 2015, Expanded Abstracts, 5595–5599.
    [Google Scholar]
  3. Price, K., Storn, R. M. and Lampinen, J.A.
    [2005] Differential Evolution: A practical approach to global optimization. Springer Science and Business Media, Berlin.
    [Google Scholar]
  4. Tsvankin, I.
    [1997] Anisotropic parameters and P-wave velocity for orthorhombic media. Geophysics, 62(4), 1292–1309.
    [Google Scholar]
  5. Zhou, R, Zhu, J. Lynn, H. and Knapo, G.
    [2015] Determining P-wave azimuthal anisotropy from walkaround VSP with offset-dependent slowness corrections. SEG Technical Program 2015, Expanded Abstracts, 5585–5589.
    [Google Scholar]

Data & Media loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error