Near-surface azimuthal anisotropy analysis based on first arrival traveltime

Not only does the near surface azimuthal anisotropy affect P-wave travel time and amplitude of deep target, it has a great influence on first arrival traveltime. The near surface model building and static correction methods based on isotropy assumption can’t solve this problem effectively. To understand the effects of the near surface azimuthal anisotropy on the first arrival traveltime, firstly, the basic isotropic refraction equation is extended to the azimuthal anisotropic medium; and then through a very simple two-layer HTI medium model, the effect of the near surface azimuthal anisotropy on the first arrival traveltime and the regular variations of the first arrivals of the same offset with the observation directions are shown, which is consistent with the variation of the first arrival traveltime observed in practice. Compared with the effect of azimuthal anisotropy on travel time, the effect of near surface azimuthal anisotropy on the delay time is relatively small. Also, the estimated result of the near surface anisotropic parameters by using the variation of the first arrivals with the azimuth on real data are shown, and the maximum amplitude of the anisotropy reaches 32%. This information provides the possibility of eliminating the influence of the near surface azimuthal anisotropy on seismic imaging. Presentation Date: Wednesday, October 14, 2020 Session Start Time: 1:50 PM Presentation Time: 3:30 PM Location: Poster Station 5 Presentation Type: Poster