Wave-equation prestack depth migration for sub-basalt P and converted wave imaging

Morgan Brown, Biondo Biondi, and Clement Kostov

morgan@sep.stanford.edu, biondo@sep.stanford.edu, clement.kostov@westerngeco.com

ABSTRACT

We apply 2-D wave-equation prestack depth migration to a North Sea basalt dataset. High velocity and impedance contrasts across a basalt layer causes low P-wave reflection signal-to-noise ratio under the basalt. We first migrate the P-wave data with a provided depth velocity model, and then replace sub-basalt P-wave velocity with a simple estimate of shear wave velocity and migrate locally-converted shear waves. Angle domain common image gathers assist our interpretation of a sub-basalt converted wave.