Acoustic/elastic wavefield injection and reconstruction from ocean-bottom data for elastic RTM Available to Purchase

In ocean-bottom seismic surveys, recorded 4C data include acoustic pressure and three-component particle velocities, in which the up-/down-going P/S waves are widely mixed and overlapped in time and space. Usually, specific wavefield separations are performed in the data domain, followed by migration imaging in a conventional processing workflow under the acoustic assumption. Alternatively, the separation can be implicitly embedded in an elastic migration engine, such as the elastic reverse time migration (ERTM). Under the latter category, according to the representation theorem integrals, we proposed a new method for separating the recorded multicomponent ocean-bottom data into up-/down-going acoustic/elastic waves by using a wavefield injection and reconstruction approach. The recorded boundary values are treated as equivalent point sources, and injected into acoustic and/or elastic domains causally or anticausally in time. We use the MacCormack finite-difference (FD) as the wave propagator, the collocated-grid property of which guarantees the accuracy of the proposed method. We further apply the time-reversely reconstructed up-going elastic waves as the receiver-side wavefields in the ERTM, and depth images of different wave modes are generated. A variety of numerical examples validate the proposed method.