WAVE-EQUATION MIGRATION VELOCITY ANALYSIS USING IMAGE WARPING

An objective function is disclosed that extracts the velocity error information directly in the image domain without computing common-image gathers. Because of the dimensionality of the problem, gradient-based methods (such as the conjugate-gradient algorithm) are used in the optimization procedure. In order to include the full complexity of the wavefield in the velocity estimation algorithm, a two-way (as opposed to one-way) wave operator is considered, where the imaging operator is not linearized with respect to the model parameters (as in linearized wave-equation migration velocity analysis), and the gradient of the objective function is determined using the adjoint-state method. The velocity estimation methodology is illustrated with a few synthetic examples.