Elf Aquitaine's came from three French oil companies: Régie Autonome des Pétroles (RAP), Société Nationale des Pétroles d'Aquitaine (SNPA), and Bureau de Recherches de Pétroles (BRP). The three companies were formed after the discovery of a gas field in Saint-Marcet in the Aquitaine region of south-western France. In December 1965 RAP and BRP merged to form Entreprise de Recherches et d'Activités Pétrolières (ERAP).