Workflow for an initial model of seismic tomography

Abstract

Initial model is one of the essential steps in achieving the final model from field seismic data, particularly in dealing with highly non-linear seismic traveltime and full waveform tomography. Most of the traveltime tomographic algorithms use local optimization methods due to the complexity/non-linearity involved into the geophysical inversion. In finite-difference modelling we use uniform grid parameterization that cannot explicitly incorporate prior information. Further, significant reflectors identified from the seismic section need to be utilized as a prior to construct pseudo-2D model similar to the study of Sibuet et al. Here we propose a simple accumulated workflow to build a good initial model by juxtaposing 1D velocity models derived by well-known intercept-time method at different segments along the seismic line and parameterizing the subsurface by trapezoidal blocks. The proposed workflow facilitates the users to include prior information such as geological faults, floating reflectors, low velocities etc. to mitigate the non-linearity of inverse problem. This workflow can be extended to 3D data also.