PRESTACK ELASTIC GENERALIZED-SCREEN MIGRATION METHOD FOR SEISMIC MULTICOMPONENT DATA

摘要

The present invention relates to a one-way wave equation prestack depth migration method for seismic wave multi-component data which uses an elastic generalized-screen (EGS) wave propagator capable of effectively expressing a movement of an elastic wave undergoing mode conversion between a P-wave and an S-wave while spreading through a boundary surface of an underground medium by expanding an existing scalar generalized-screen (SGS) scheme to an elastic wave equation, and the SGS allowing a rapid propagation calculation of the wave in a media where a horizontal speed change exists. According to the present invention, a Taylor series expansion of a vertical slowness term of the propagator is expanded up to a secondary term, thereby calculating a wave field with further higher accuracy in the medium having a complicated structure. Also, a mode separation operator is included in the propagator such that shot gather is directly used as a migration input without the need to divide multi-component data into the P-wave and the S-wave, thereby generating a P-wave image section and an S-wave image section. Furthermore, correction with respect to polarity-conversion is performed in a wave number-frequency area after visualizing the S-wave, thereby improving a quality of an S-wave migration image.