Multi-parameter inversion of frequency-divided zero-offset VSP wave equation based on traveltime constraint

In seismic exploration, forward modeling and inverse problems of describing complex media usually contains many parameters which reflect the different properties. In order to improve the accuracy of zero offset VSP multi-parameter inversion in the frequency domain, the feasibility of such inversion is analyzed. The sensitivity of the objective function and the coupling between the parameters are clarified, and a strategy for frequency-divided wave equation multi-parameter inversion based on traveltime constraint is proposed. First, the prior information is constructed by using the zero offset VSP data, then a two-step inversion is carried out on low-and high-frequency data, which is a process of "three parameter inversion + five parameters inversion", in order to improve the robustness and accuracy of the inversion. By using this method, the reliable elastic wave velocities, density and quality factors of the zero offset VSP data can be obtained simultaneously. It lays a foundation for accurate time depth relationship and interpretation and prediction of oil and gas. It can also provide a reliable constraint for the ground seismic pre-stack inversion and enhance accuracy of ground seismic inversion.