Abstract:Lateral interval-velocity variation in a target stratum can be determined by performing travel time inversion of prestack common-shot gathers (or common-midpoint gathers). Interval velocities are evaluated by minimizing the difference between observed travel time and travel time derived from forward modeling. Ideally, this method is identical with seismic reflection tomography, which, however, involves more parameters, so that inversion process is unstable, and solution multiple, Some measures, such as reasonable geological model, equivalent layer and equalization of Jacobi matrix elements, are taken to achieve less parameters; stable inversion process and definite solution. Good results have been obtained in the practice.Travel time inversion principle and relevant technical problems are discussed, and work steps given. The example is given of applying this method to Daqing seismic data inversion.