Wave equation datuming

In this appendix, the basic strategy for finding a datuming operator consists of first formulating a forward-modeling operator and then deriving the corresponding datuming operator by transposing and taking the complex conjugate of the forward-modeling operator. For poststack or zero offset sections, the forward modeling is an algorithm that extrapolates the wavefield upward from a flat surface to an irregular surface by the one-way wave equation, using half the velocity of the medium. The modeling algorithm is derived so that it can be used with any depth extrapolation technique, including the phase-shift, split-step Fourier, and finite-difference methods.