From a speck on the horizon where sea and sky merge, a pilot flame is the first thing visible to helicopter passengers flying towards one of the newest offshore oil platforms transforming Brazil into a global energy power.

Anchored 200km from Rio de Janeiro, the P-71 floating production unit is among more than 30 run by national oil company Petrobras over a hydrocarbon-rich stretch off the country’s south-eastern Atlantic coast.

The expanse is known as the “pre-salt” region because its crude deposits — 11.5bn proven barrels at the last count — lie under a thick crust of sodium chloride, deep beneath the ocean floor. It was home to an oil discovery considered the western hemisphere’s most significant for 30 years in the first decade of this century.