Research On Elastic Wave Propagation Characteristics And QP Wave Depth Migration Method In TTI Media

Seismic anisotropy has been one of the latest scientific research topics in seismology, and also it is a great challenge for seismology theory study and application. Carrying out seismic anisotropy research has great academic significance and applied value for the cognition of earth media configuration, the exploration and development of complex oil gas reservoir, the forecast of the geological disaster. For the ubiquitous anisotropic media in the sedimentary rock, the elastic wave propagation characteristics in the TI media, the decomposition of elastic wave equation, one-way dual-domain propagation operator for qP wave and the wave equation depth migration imaging method in VTI media are systematically studied.Phase velocity and group velocity are important characteristics of elastic wave propagation. According to the elastic wave Christoffel equation in TTI media, we have a research on phase velocity, group velocity and polarization direction for elastic wave propagation in TTI media. Based on them, elastic reflection characteristic and transmission characteristic in TTI media are discussed, which provides a basis for anisotropy AVO study.Wave equation decomposition plays a very important role in the research of seismic migration imaging and multi-component seismology. The decomposition of elastic wave equation in TTI media is carried out on the base of Thomsen weak anisotropy theory and acoustic assumption condition. The result shows that high accuracy wave equation describing qP wave propagation in the TTI media can be obtained through wave equation decomposition, which plays a foundation for studying one-way dual-domain propagation operator in VTI media and establishing depth migration algorithm in VTI media.In the process of wave equation depth migration imaging, the core things of seismic migration imaging are the wave field propagation operator and the algorithm flow. On the basis of qP Wave equation in VTI media, we thoroughly studies Born one-way dual-domain propagator for qP wave in VTI media. The operator consists of the extended local Born approximate operator in isotropic media and anisotropic perturbation operator. Basing on one-way dual-domain propagator in VTI media, the qP wave depth migration algorithm flow in anisotropic media is established, and prestack and poststack depth migration are carried out. Not only prestack depth migration but also poststack depth migration has obtained good imaging results, and these results validate the accuracy, validity and compatibility of depth migration imaging operator in VTI media.