Anisotropic Waveform Tomography: Application to Crosshole data for Transversely Isotropic Media
Abstract
Anisotropic Traveltime Tomography and Full Waveform Inversion were applied first to synthetic and then to real data following the development of a transversely isotropic model for handling anisotropy. Best-fitting models of seismic velocity and Thomsen's anisotropy parameters were initially obtained from traveltime tomography, and then used as the starting models for Full Waveform Inversion. The use of a Laplace transform approach effectively damps late arriving S-wave artifacts that introduce errors into the modelling process. The results of the synthetic study highlights the tradeoffs in resolution between the two parameter classes, but verify anisotropic traveltime tomography as a valid method for generating starting models for Full Waveform Inversion. The joint technique was then applied to field gathers from Western Canada and compared to a similar analyses that used a simpler anisotropy model. The transversely isotropic approach yielded a Full Waveform Inversion model with superior resolution that better predicted the true data.