Near‐surface velocity estimation by weighted early‐arrival waveform inversion

Abstract

Early‐arrival waveform inversion is by far the most theoretically accurate near‐surface velocity estimation tool. It tries to estimate velocity by matching recorded early arrivals with observed early arrivals based on the finite‐frequency wave equation (Pratt et al., 1998). In practice, good waveform inversion results rely on several important factors. One of the most important factors is the ability of the inversion engine to generate wave phenomena that exist in the recorded data. Ideally, we would like to include and invert all the physical parameters in the inversion. However, because of such limitation as computational power, instability of inverse problem and quality and understanding of the available data, the acoustic wave equation is currently the most practical choice for the waveform inversion kernel. In this case, the objective function of conventional waveform inversion is insufficient to bridge the gap between the physics of the inversion engine and the physics of the recorded data. In this paper, I present a modified version of the conventional waveform inversion objective function to bridge the gap between the acoustic waveform inversion engine and the more complicated physics in recorded data.