Traveltime Tomography of qP Reflection Waves in Anisotropic TI Media

Abstract

AbstractSeismic traveltime tomography is an effective method to invert underground anisotropic parameters. Research about tomography for anisotropic media is, however, relatively a little. And its techniques are still far from mature stage. In real applications, traveltime inversion of qP reflection waves has more extensive practical values, because the cost of surface survey is much cheaper than that of crosshole and vertical seismic profile surveys. The tomographic method suggested in this article combines the anisotropic reflected wave ray tracing, traveltime perturbation equation and nonlinear conjugate gradient method. It can be used to invert anisotropic media with arbitrary anisotropic degree. The main task in this article is to reconstruct the anisotropic parameters for TI media using qP reflection waves. In numerical simulation, traveltime of qP reflections wave was used to invert for the layered and block anomaly model, respectively. The elastic modulus parameters and Thomsen parameters were inverted separately, because the velocity sensitivity functions of them are different. The simulation results show that traveltime of qP reflection waves can be used to invert anisotropic parameters correctly. Iteration reaches a satisfactory convergence level for different anisotropic models. The tomographic method proposed here has a better capability in recovering theoretical models compared than isotropic traveltime tomography.