Pure P- and S-wave elastic reverse time migration with adjoint state method imaging condition

Jorge E. Monsegny and Daniel Trad

ABSTRACT

We implemented an elastic reverse time migration based on a coupled system of pure P- and S-wave particle velocities. The system utilizes finite difference wavefields for Pand S-wave particle velocity in vertical and horizontal directions ( v px , v pz , v sx and v sz ), and for 2-D displacement divergence and curl ( A and B ). In contrast with the usual elastic imaging conditions that cross-correlates vertical displacements to obtain the P-wave image and vertical and horizontal displacements to obtain the converted wave image, we devised P- and S-wave imaging conditions using the adjoint state method. The resulting imaging conditions cross-correlate spatial derivatives of A and B wavefields with P- and S-wave displacements. The proposed migration shows a better reflector definition and more balanced amplitudes than the usual vertical and horizontal particle displacement cross-correlations.

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