Integrating Geology and Depth Imaging in a Mature Overthrust Area - A Case History

We present a depth-domain processing flow-chart based on iterative ray+Born migration/inversion and Very Fast Simulated Annealing (VSFA) inversion. The quantitative migrated image computed by ray+Born inversion is used as an input in the VSFA inversion to build a structural velocity model. Aim of the VSFA inversion is to remove limited-bandwidth effects in the migrated image resulting from the limited bandwidth of the source and the limited aperture coverage. The input data of the VSFA inversion are velocity profiles of the migrated images and the output models are the corresponding structural velocity profiles. The forward problem associated with the VSFA inversion is approximated by a time-domain convolution with the source wavelet, which makes a global exploration of the model space to be possible.<br>The flow-chart is assessed thanks to the Marmousi model. We computed 9 iterations of single-arrival ray+Born modelling/inversion, which allowed us to derive an accurate true-amplitude migrated image. Second, we applied the VSFA inversion using as input all the vertical profiles of both the true perturbation model (obtained by band-pass filtering the Marmousi model) and the ray+Born migrated image. The output is a structural velocity model, which mimics the true Marmousi model.<br>