Image-domain Wavefield Tomography for Complex Geologic Structures

Waveform inversion is a costly but accurate technique for model building. This method places huge demands on the data by requiring extremely low frequencies to reduce cycle skipping. An alternative formulation can be implemented in the image-domain, and it is based on extended common-image-point gathers. The data- and image-domain implementations share the source and receiver wavefields as information carriers. Both methods make use of the adjoint state method to estimate a gradient used to search for a model update. Since the image-domain implementation is based on correlation instead of differencing, it can handle more realistic and higher frequency wavefields. Synthetic examples demonstrate that the image-domain implementation constrains well the velocity model, while preserving all other important characteristics of its data-domain counterpart.