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Valencia Trough (Offshore Spain): Petroleum Systems and Play Types


The Western part of the Mediterranean Region is one of the least explored areas for hydrocarbons in the entire Tethys region. The Valencia Trough, offshore Spain, is located between the Catalan coast and the Balearic Islands and it represents one of the most attractive basins for HC exploration using new concepts and technologies. The petroleum system of the Valencia Trough has been recently reviewed and integrated with 1D basin models on some wells, focusing on the evaluation of the source rock, the reservoir and the seals. The oldest reported source rock in the area is the Upper Jurassic Mas D'Ascla Fm (highest TOC value 1.26%). In the easternmost part of the Valencia Trough, Paleogene continental rift basins formed before the Early Miocene major rifting phase are characterized by the presence of continental and lacustrine sediments. Locally there are evidence of coal, with TOC values up to 11.5%, and a thickness of 150m. In the Miocene Alcanar Group there are organic-rich units that are considered to be the most prolific source rock of the Valencia Trough. The intervals rich in organic matter are in the Burdigalian-Langhian sequences. The most important reservoir of the Valencian Trough is characterised by karst limestones and dolostones, of Cretaceous and Jurassic age. The karst development generated diffuse vuggy porosity and enhanced fracture porosity. Clastic reservoirs are not exploited, but traces of hydrocarbons have been found in the Castellon Group, whereas the Pliocene Ebro sandstones are considered a potential good reservoir for biogenic gas. The main seals are represented by the shales of the Cambrils Group, of the Castellon Shales and the shales intercalated in the Ebro Group. A review of all the available data (seismic and wells), allow to define 4 different plays in the area. The petroleum plays in the Valencia Basin involve both carbonates and clastic sequences and range from Mesozoic structural and structural-stratigraphic traps to Plio-Pleistocene delta and turbidite deposits. They can be sub-divided into: Casablanca and Amposta Play, Castellon Play, Ebro Play and Rosas Play.