Combining forward-scattered and back-scattered wavefields in velocity analysis

Combining forward-scattered and back-scattered wavefields in velocity analysis

Ali Almomin, Biondo Biondi, and Robert Clapp

Abstract:

Wave-Equation Migration Velocity Analysis (WEMVA) is a family of techniques that aims to improve the subsurface velocity model by minimizing the residual in the image space. This process is performed iteratively by linearizing the imaging operator in order to relate image perturbations to model updates. However, WEMVA techniques only utilize the kinematics in the forward-scattered wavefield. Ignoring the back-scattered wavefield results in model updates that have low vertical resolution. I present a method that combines the forward-scattered wavefield information from WEMVA with the back-scattered wavefield information from full-waveform inversion (FWI). This can be done by first decomposing the FWI gradient into forward- and back-scattered gradients, and then applying the proper weights to combine the back-scattered FWI gradient with the WEMVA gradient. These weights aim to enhance the components of the FWI gradients that overlap with the WEMVA gradient. Preliminary results show that the combined gradient converges faster and to a better solution.

Combining forward-scattered and back-scattered wavefields in velocity analysis