Geometries and sedimentary heterogeneities in high sinuosity fluvial deposits: a case study from the Capella Formation (Middle Eocene, Graus-Tremp Basin)

The studied succession of the Middle Eocene Capella Formation in the Graus-Tremp Basin is characterized by high sinuosity fluvial deposits. The sedimentological logged section and the obtained outcrop digital model have allowed to identify up to 3 different facies associations. These include: 1) channel fill, 2) point bar and 3) overbank deposits, showing up to three different sand-prone geobody types. Vertically, the reservoir sand-prone geobodies are often disconnected one from each other by fine-grained facies, becoming potential vertical fluid flow barriers. However, horizontally, the geobodies are frequently connected due to channel incision over underlying sand prone geobodies, as well as by contact of crevasse splays and point bars with the main channel fills. The exceptional outcropping conditions of the studied section, make this formation as an excellent outcrop analogue for similar fluvial reservoirs with comparable features in the subsurface.