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Construction of a 4-D Synthetic Model of a Turbiditic Reservoir: The Pab Channel Complex

Tristan Euzen, Aline Bourgeois, Julien Cap, Brigitte Doligez, Remi Eschard, and Karine Labat
Institut Français du Pétrole, Rueil Malmaison Cedex, France

This poster presents the methodology used for constructing a 4D synthetic model, based on the detailed 3D interpretation of an outcrop analog of deep offshore reservoirs (Pab Fm., Pakistan). The Lower Pab channel complex consists of several multi-story individual channels stacked vertically or migrating laterally depending on the local confinement. By-pass deposits draping erosional surfaces, margin collapse debris flows or internal levees and crevasses constitute the internal heterogeneity of such a reservoir. These small-scale heterogeneity, often below seismic resolution, may have a strong impact on the fluid behavior during water injection and production.

The methodology for the construction of the model consists of four main steps (1) A fine-scale 3D geo-cellular model was built and populated with sedimentary facies and petrophysical and elastic properties, using deterministic and geostatistical approaches. (2) Seismic modeling was performed on the reference model using 1D convolution method. The results is different angle stacked cubes generated for different angle ranges and corresponding to synthetic prestack seismic data. (3) Dynamic modeling of water injection and oil production was then carried out on the fine-grid model at the field scale. (4) Time lapse seismic modeling will be achieved on the same model, after the updating of elastic parameters, due to saturation and pressure variations.

This synthetic model will be used as a virtual reservoir, by extracting well and seismic data and by applying various reservoir characterization tools and methods. The qualitative and quantitative comparison of the outputs with the 4D reference model will provide a unique opportunity to bench-mark these advanced reservoir characterization techniques and design an optimum workflow for reservoir monitoring.