2D/3D Simultaneous Inversion For Velocity And Reflector Depth Using Multi-phase Fresnel Volume Rays

Traditional ray tomography method based on high frequency assumption is unable toobtain a high resolution tomographic picture with sparse rays. Actually, seismic wave energytravels along not only on the central geometric ray, but also within a volume around thecentral ray. This volume region is referred to the First Fresnel Volume. Therefore, it is usefulto exploit such a Fresnel Volume in real application.Some simple and efficient methods were put forward to calculate the Paraxial FresnelVolume ray, and we’ll use such a ray for2D tomography. Due to the Paraxial Fresnel Volumeis not a real Fresnel Volume, we use the accurate Fresnel Volume solution for3D seismictomography. Here we first put forward an algorithm to calculate multi-phase Fresnel Volumeray, and then give an inversion method to simultaneously invert both velocity and reflectorgeometry by using these multi-phase traveltimes and finally compare it with the traditionaltraveltime tomography.The results show that the Fresnel Volume ray tomographic method is advantageous overthe traditional ray tomographic method in terms of velocity reconstruction and reflectorgeometry updating when the ray density is low. The Fresnel Volume ray tomographic methodwith varying frequency is a good choice in real seismic tomographic application. The resultsof algorithm validity tests and sensitive error tests show that Fresnel Volume ray tomographymethod is not sensitive to both the initial model parameters and travel time errors, which has apractical value in real application.