Q-Compensated Least-Squares Reverse Time Migration of Different-Order Multiples

Multiples have longer propagation paths and smaller reflection angles than primaries, so they cover larger illumination area. Therefore, multiples can be used to image shadow zones of primaries. Least-squares reverse time migration of multiples can produce high quality images with fewer artefacts, high resolution and balanced amplitudes. However, viscoelasticity exists widely in the earth, especially in the deep-sea environment, and the effect of attenuation on multiples is more serious than primaries because multiples have longer propagation paths. To compensate for Q attenuation of multiples, Q-compensated least-squares reverse time migration of different-order multiples is proposed by deriving Q-compensated born modeling operators, Q-compensated adjoint operators and Q-attenuated demigration operators for different-order multiples. Based on inversion theory, this method compensates for Q attenuation along all the propagation paths of multiples. A stabilization operator is introduced to suppress exponential high frequency noise. Example on a modified attenuating Sigsbee2B model suggests that the proposed method can produce better imaging result than Q-compensated least-squares reverse time migration of primaries and noncompensated least-squares reverse time migration of multiples.