An Improvement of Velocity Variation with Offset (VVO) Method in Estimating Anisotropic Parameters

Abstract

Seismic anisotropy causes deviation of traveltime
reflection from hyperbolic moveout. The deviation can be seen at
far offset and its deviation depends on anisotropic parameter and
offset. This paper discuss velocity variation with offset (VVO)
method as a tool for estimating anisotropic parameters; ε and δ.
Anisotropic parameter is one of important aspect in seismic
anisotropy analysis. While other methods use non-hyperbolic
moveout for estimating anisotropic parameter, VVO method uses
hyperbolic assumption for moveout correction and leave reflector
unflat at far offset because anisotropy. The method calculates
residual traveltime and then changes it into anisotropy velocity to
obtain anisotropic parameter using linear inversion method. This
paper provides an improvement and limitation of VVO method
in estimating anisotropic parameter. Comparison between VVO
method and other established method is discussed theoretically in
this paper. To test the method, synthetic model is built and the
result show promising outcome in predicting ε. Meanwhile
accuracy for δ estimation depends on accuracy of moveout
velocity. Advantage of VVO method is that ε and δ can be
estimated separately using P-wave gather data without well
information.