Impact of seismic data conditioning on the identification of structural elements: A case of study from the pre-salt reservoir, Santos Basin, Brazil

Abstract

Three-dimensional seismic data provides valuable insights into structural interpretation when dealing with naturally fractured reservoirs. The faults or fractures may control the direction of fluid flow in the reservoirs, especially during the sensitive analysis in projects of carbon sequestration and reservoir development, since these features may impact the rock-fluid interaction and oil field production. However, characterizing faults and fractures in pre-salt reservoirs using conventional approaches is challenging due to a complex and heterogeneous overlying evaporitic unit which reduces the seismic-to-noise ratio. Therefore, seismic data conditioning targeted at improving the seismic image is necessary for quality subsurface investigations. This work provides a systematic series of filters to enhance and detect discontinuities in post-stack seismic volume, primarily by reducing migration artifacts and salt multiples, thereby maintaining the true geological characteristics of the data. We emphasize the delineation of the fault and potential fracture zones by computing seismic attributes in a post-stack time-migrated 3D seismic in the Santos Basin's deep waters. Initially, the seismic signal-to-noise ratio was analyzed, and a sequence of structural-oriented filters and spectral balancing was applied to generate vertically refined images with enhanced seismic amplitudes. To assess the quality of the conditioned data, we employed the Similarity and Curvature attributes to identify the distribution of discontinuities and compare the before-and-after denoising approach. The data conditioning and analysis of seismic attributes improved our understanding of the distribution and compartmentalization of the reservoirs, highlighting predominantly NE-trending discontinuities. The systematic processing significantly improved the signal-to-noise ratio, allowing us to identify the relative direction of structural elements and insights into potential fractured zones over the reservoir.