An extension of least-squares redatuming: Simultaneous reconstruction of overburden reflectivities and virtual data

Abstract

In a controlled-source seismology scenario, scattered wavefields from deep targets, e.g., the petroleum reservoirs, are often distorted by strong heterogeneities of the overburden media, complex topography and irregular acquisition. It is key for target-oriented seismic imaging to accurately reconstruct the scattering wavefields from the deep structures. Recent studies have promoted seismic redatuming for removing the imprint of the overburden through reconstructing virtual data just above the target area. Among the model-based redatuming approaches, least-squares inversion has advantages in mitigating the artifacts due to limited recording aperture and irregular spatial sampling, and allowing for the introduction of appropriate constraints to the reconstructed data. However, conventional least-squares redatuming (LSR) suffers from the spurious events and noises associated with the wavefield interaction of the overburden reflectivities close to the datum. To overcome this problem, we establish an efficient double-parameter LSR method that simultaneously updates the overburden reflectivities and the virtual data through a constrained optimization. Synthetic and field data examples demonstrate that this extended LSR method can effectively retrieve the scattering wavefields from the deep part and improve the target-oriented prestack depth migration below the datum.