A workflow combining Kirchhoff single-stack redatuming and common-reflection surface-based enhancement for depth imaging: A case study

Abstract

Seismic datasets acquired in onshore basins typically present a great challenge for seismic depth imaging due to the poor quality of the prestack data caused by inherent acquisition difficulties and, in particular, the distortion of the seismic signal caused by topography and heterogeneity of the weathering zone. In this seismic data, the standard static correction does not give satisfactory results in depth imaging. Wave-equation-based redatuming is an alternative solution to this problem, as it correctly moves the data measured on the terrain surface to a new flat datum. But most redatuming techniques require knowledge of an accurate near-surface velocity model. A new workflow for depth imaging of land data is proposed by combining Kirchhoff single-stack redatuming and prestack data enhancement by common-reflection surface stack method. A major advantage of this redatuming method is that it only requires a good approximation of the near-surface velocity model to properly remove distortions in the seismic signal caused by the rugged topography and weathering zone. A new algorithm is introduced to apply Kirchhoff single-stack redatuming to multi-coverage land seismic data. Common-reflection surface-based prestack data enhancement is applied after redatuming to attenuate radon noise and enhance coherent event. The proposed workflow has been successfully applied to land seismic data from the Parnaíba Basin in northeastern Brazil, transforming surface-referenced prestack data to a new flat datum. By applying common-reflection surface-based enhancement to the redatumed prestack data, a significant improvement in signal-to-noise ratio and enhancement of reflections was achieved. The depth-migrated image confirms the great improvement in quality, where the reflectors show strong enhancement and better continuity throughout the section, compared to the migrated image obtained from the only redatumed data. This improvement in quality was important for the interpretation of the main reflectors of the geological formations.