Estimation of anisotropy parameters in VTI media from surface P -wave seismic data and VSP in Tarim Basin, China

Nonhyperbolic moveout caused by anisotropy and the vertical inhomogeneity of velocity in VTI media is now routinely observed on the wide azimuth seismic data in some areas of Tarim Basin, China. In this paper, we developed a new method, utilizing wide azimuth seismic data and five VSP wells to estimate the Thomsen parameters for use in anisotropic seismic data processing. The instantaneous anisotropic parameter δ is attained from seismic data and one zero-offset VSP well. The anisotropic parameter ε is then acquired from four offset VSP wells on the base of the attained accurate depth and thickness of anisotropic igneous rock layer. Taking the effect of inhomogeneity of velocity into account, the anisotropic parameter ηeff is attained finally. The image is improved greatly by anisotropy velocity analysis in VTI media using the anisotropic parameters acquired.