The Annot Sandstone Outcrops (French Alps): Quantification and 3D Modeling of The Reservoir Architecture

Joseph, Philippe, Nathalie Babonneau, Aline Bougeois, Gilles Cotteret, Rémi Eschard, François Fournier, Blaise Garin, Institut Français du Pétrole, 1-4 avenue de Bois-Préau, 92506 Rueil Malmaison; Olinto Gomes de Souz a, Petrobras, Cidade Universitaria, Quadra 7, Ilha Do Fundao, Rio de Janeiro, Brazil; Didier Granjeon, Institut Français du Pétrole, 1-4 avenue de Bois-Préau, 92506 Rueil Malmaison; François Guillocheau, Géosc iences Rennes, Campus de Beaulieu, 35042 Rennes, France, Benoît Guivarc'h, Olivier Lerat Institut Français du Pétrole, 1-4 Avenue de Bois-Préau, 92506 Rueil Malmaison, Jean-Marie Quemener, Géosciences Rennes, Campu s de Beaulieu, 35042 Rennes, France, and Christian Ravenne, Institut Français du Pétrole, 1-4 avenue de Bois-Préau, 92506 Rueil Malmaison

Abstract

The Eocene Annot Sandstone in the French Alps corresponds to a sand-rich turbiditic system up to 1000 m thick, which has filled large morphologic furrows induced by alpine tectonics. Detailed field studies have recently been undertaken on well-exposed outcrops, in order to analyse and reconstruct the architecture of deep-water gravity deposits (turbidites, slumps and debris-flows).

The studied sites have been selected in order to cover a wide range of sedimentary settings (proximal, mid and distal fans), morphological configurations (narrow furrow controlled by faulting, unconfined basin), and sources of sediment (Southern Corso-Sardinian Massif, eastern Alps). The reservoir architecture has been reconstructed from the measurement of vertical sedimentological sections, the mapping of sand units, the calibration and interpretation of continuous photo-mosaics of the outcrops.

In a sequence stratigraphy framework, a quantification of the size and vertical/horizontal distribution of facies and architectural elements has been done, then 3D grid blocks of the geometry and facies distribution of the reservoir units have been reconstructed, using geomodelling and geostatistical tools. Synthetic seismic and fluid flow modelling has been performed on these 3D blocks in order to test their seismic and dynamic response. These 3D models may be used to optimize the development of specific deep-water reservoirs, by providing guidelines for correlation, and giving access to quantitative parameters used for the stochastic reservoir modelling; geometrical characteristics of reservoir bodies (channel, lobes) and permeability barriers (shale breaks, calcite concretions); geostatistical parameters of the lithofacies distribution (proportions, correlation lengths, etc.).