NONLINEAR INVERSION OF SEISMIC-REFLECTION DATA IN A LATERALLY INVARIANT MEDIUM

Interpretation of seismic waveforms can be expressed as an optimization problem based on a nonlinear least-squares criterion to find the model which best explains the data. An initial model is corrected iteratively using a gradient method (conjugate gradient). The method is general and can handle arbitrary 2-D source-receiver configurations and lateral heterogeneities. Using conventional velocity analysis to derive an initial velocity model, the method is implemented on a real marine data set. The data set corresponds approximately to a horizontally stratified medium. Consequently, a single-shot gather has been used for inversion. In spite of some simplifying assumptions used for wave-field propagation and using synthetics generated by a nearby sonic log to calibrate amplitudes, the final synthetics match the input data very well and the inversion result has clear similarities to the log. -from Authors