Abstract:Most existing migration methods are based on single-way wave solution of wave equation and exploding reflector model, so that the image and migration of the reversed reflector whose dip is higher than 90° can be hardly achieved using them. We first adopt the WKBJ method to solve for wave equation (including upgo-ing wave and downgoing wave) in the case where medium varies with depth, then apply the improved WKBJ method to determination of expression for solution coefficients, and finally derive the migration formula from exploding reflector model. Theoretical and practical data processings with the use of the formula show that this method can successfully image and migrate the reversed reflector whose dip is higher than 90°. What is more, this method results in less amplitude distortion and weaker "arc phenomenon "than other methods. It also brings high efficiency when migration skill is proper.