Accurate linear interpolation in the extended split-step migration

Hermes Malcotti and Biondo Biondi

hermes@sep.stanford.edu, binodo@sep.stanford.edu

ABSTRACT

We present an implementation of the extended split-step migration method for strong lateral velocity gradients. Steep events are imaged by using the evanescent energy in the linear interpolation of different downward continued wavefields in every depth step and between reference velocities. The 3-D algorithm is a 3-D prestack operator based on common-azimuth continuation at every depth step. We show the extended split-step impulse response with a strong lateral velocity gradient of 0.5 s^-1, and we apply the migration algorithm over two synthetic data sets: a 2-D salt dome model and the 3-D SEG-EAEG data set. In addition, we show the resulting prestack migrated image of the real data set that used to built the 2-D salt dome model. Our results show that the evanescent energy is important in the linear interpolation to preserve steep events in a strong lateral velocity gradient.