The Sismage Geotime Technology: 3d Sequence Stratigraphy of Dalia Field Angola
Antoine Massala, Sebastien Guillon, and Noomane Keskes
Total E & P Angola, Luanda, Angola
Understanding the 3D geometry of depositional sequences in a turbiditic environment is a key issue to field development. To perform seismic segmentation, one must pick discontinuities in 2D with a global 3D understanding of the environment. Interpretation in such an environment is always undertaken using both geophysical and geological information: seismic marker geometry (onlap, toplap) and wells.
Based on Vail’s (Exxon) research on sequence stratigraphy, the Sismage team has been working for 20 years on image processing technology to automatically derive a wheeler diagram. This research lead to GeoTime, an automatic tool for seismic chrono-stratigraphic analysis. (Sismage a proprietary software developed by Total).
The GeoTime approach consists of transforming seismic data in pseudo geological time, enhances the understanding of the depositional geometry in 3D. In addition, the automatic building of a wheeler diagram with GeoTime reconciles geophysical and geological interpretations.
This methodology was successful in the Moho-Bilondo project (Congo) and Anguille NE field (Gabon); and has been applied to the Dalia field (Miocene turbidites, Angola). The understanding of the complex channel geometries and dynamic behaviour is important for that field.
The challenge was to accurately and rapidly determine the limits of intra-sequences (depositional sequences bound at their top and base by unconformities) using wells and seismic data. In this environment, seismic picking and well correlation are two difficult tasks due to the juxtaposition of erosive systems.
Thanks to the GeoTime approach, all the depositional sequences were identified and picked very quickly as 3D bodies. Then the 3D visualisation capabilities of Sismage were useful to display the bodies and understand the complete 3D reservoir organisation within the field.
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