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A narrow azimuth survey and an overlapping Coil survey were acquired and processed for TOTAL offshore Angola. After fast track processing, a direct comparison showed that at a specific location a subsalt steeply dipping event was better defined on narrow azimuth image than on the Coil image. This case study illustrates how illumination analysis can be used to make critical survey design, acquisition and processing decisions. The initial flower plot analysis helps determine the survey design requirements to illuminate target horizons, and will fully justify the need for a full azimuth design. Then, an acquisition illumination analysis complements the previous analysis by creating offset and azimuth illumination maps for chosen design. This identifies illumination and shadow zones on the target horizon. This can be directly related to the seismic data and used to design an appropriate processing solution. Finally, during the processing phase, the specific azimuth contributions identified from illumination analysis need to be separated into azimuthal images. These are intelligently stacked to create the final image, using an intelligent stacking method, designed to retain azimuth specific contribution. To use the full benefit of Coil Acquisition, this two-steps processing strategy derived from the illumination analysis, is essential.

SummaryBlock 32, deep offshore Angola, is located in an area of the Lower Congo Basin heavily affected by the salt tectonism: salt domes or canopies are extensive. As a consequence having a good seismic image is critical in terms of exploration but also development of discoveries. Over the past decade the focus has moved towards the sub-salt play and the use of conventional seismic has reached its limits. As a consequence, Total E&P Angola embarked in 2012 in a project to address complex subsalt challenges in the Central North East part of the Block 32, using innovative technologies: from survey design, to acquisition, processing and imaging. The objective was to deliver interpreters a state-of-the-art and fit for purpose solution in a timely and cost-effective manner. This project is known as the Block 32 CNE Bi WATS. This abstract aims to give a full overview of the project, from its genesis to its execution, and finally present some of the results First EAGE/ASGA Workshop on Petroleum Exploration

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