Deghosting-based reverse time migration with free-surface multiples

As seismic data are acquired below the free-surface, downgoing ghosts are the real sources of recorded upgoing free-surface multiples. Thanks to the modern acquisition with dual-sensor or over/under streamers, we can first decompose the acquired data into the downgoing and upgoing components using a deghosting method at the receiver side. We further develop an integral-compensation method for the decomposed data to reduce the source ghosts, based on the approximation that seismic data with source ghosts are excited by the time-derivative of the source wavelet. Finally, we incorporate the integral-compensated downgoing and upging data in both the reverse time migration (RTM) and the least-squares reverse time migration (LSRTM) procedures for joint imaging of primaries and multiples. Numerical experiments with two synthetic datasets validate that the proposed RTM method presents correct imaging phases corresponding to the reflectivity distributions, the LSRTM method further suppresses most cross-talk artefacts, balances the imaging amplitudes and enhances the imaging resolution, and the imaging process jointly using primaries and free-surface multiples provides wider subsurface coverage than that with primaries only.