3-D prestack full‐wavefield inversion

Abstract

A full‐wavefield inversion algorithm for direct imaging of a 3-D compressional wave velocity distribution is based on the full 3-D scalar wave equation and operates on common‐source data recorded by areal arrays. For each source, the method involves reverse‐time extrapolation of the residual wavefield. Application of the image condition by crosscorrelation with the source wavefield at each time step produces a 3-D image whose amplitude at each point is proportional to the required velocity update at that point. Convergence to local minima is mitigated against by gradually increasing the wavenumber bandwidth in the estimated 3-D velocity distribution as iterations proceed, starting from the smallest wavenumber. The algorithm is illustrated by successful application to synthetic data for a multilayered monocline, and for a multilayered structure with the geometry of the standard French model. The latter demonstrates good performance with noisy, unequally spaced data with significant elevation statics.