Applications of Waveform Inversion

Waveform inversion techniques aim to fit the entire seismic wavefield including those phases<br>that conventional processing and migration seek to remove. Such methods have the potential<br>to image the subsurface with significantly improved spatial resolution. The inversion in this<br>paper uses a frequency-domain, finite-difference modeling method to solve the full acoustic<br>wave equation, so high-order effects such as diffractions and multiple scattering are<br>accounted for automatically. It is a local descent algorithm that refines a starting model<br>iteratively to reduce the waveform misfit between observed and modeled data.<br>Waveform inversion is applied to a number of synthetic models, including the complicated<br>BP EAGE model. The results have demonstrated that waveform inversion has the potential to<br>reconstruct high-resolution velocity structure. Some practical strategies were found to be<br>critical in the application to real data. These strategies include: using a diving wave<br>tomography model as a starting model; starting the inversion with the lowest available<br>frequency; using complex-valued velocity to take care of undesired amplitude discrepancies;<br>using complex-valued frequencies to simulate the damping of late arrivals; and handling<br>surface-related multiples effectively.