In more than 2,000 metres of water off the coast of Brazil, Petrobras, the Brazilian national oil company, is drilling what could become one of most important oil wells of recent years.

Sergio Gabrielli, chief executive of Petrobras, told the Financial Times that results from a well now being drilled in the offshore Carioca field, the subject of fevered excitement, should provide some answers about its true potential in about three months’ time.