The sight of a giant oil rig being towed past may not be what sun-lovers on the beautiful beaches of Brazil’s south-east coast most want to enjoy while getting away from their workaday cares. But if reports of a coming transformation of Brazil’s oil industry are to be believed, they had better get used to it.

Last week, such reports sent the shares of Petrobras, the government-controlled oil group, its foreign partners and their suppliers all shooting upwards. The cause was the impromptu “revelation” during an oil conference by Haroldo Lima, head of the industry watchdog, that a recently-discovered deep-water field contained as much as 33bn barrels of oil – which, if confirmed, would make it the third biggest single field ever discovered.