A constrained global inversion method using an overparameterized scheme: Application to poststack seismic data

A global optimization algorithm using simulated annealing has advantages ov er local optimization approaches in that it can escape from being trapped i n local minima and it does not require a good initial model and function de rivatives to find a global minimum. It is therefore more attractive and sui table for seismic waveform inversion. I adopt an improved version of a simu lated annealing algorithm to invert simultaneously for acoustic impedance a nd layer interfaces from poststack seismic data, The earth's subsurface is overparameterized by a series of microlayers with constant thickness in two -way traveltime, The algorithm is constrained using the low frequency imped ance trend and has been made computationally more efficient using this a pr iori information as an initial model. A search bound of each parameter, der ived directly from the a priori information, reduces the nonuniqueness prob lem. Application of this technique to synthetic and field data examples hel ps one recover the true model parameters and reveals good continuity of est imated impedance across a seismic section. This approach has the capability of revealing the high-resolution detail needed for reservoir characterizat ion when a reliable migrated image is available with good well ties.