The Roncador field sits in the Campos Basin, 125 kilometers off Brazil's southeast coast, northeast of Rio de Janeiro. It covers 111 square kilometers - a buried lake of hydrocarbons trapped in sandstone reservoirs roughly 1,500 meters below the seafloor, in water itself 1,500 meters deep. The scale is vertiginous. Three billion barrels of proven recoverable reserves make Roncador one of the largest offshore fields ever discovered in Brazilian waters. Petrobras divided it into four modules based on oil quality - Module 1 with the best crude (28 to 31 degrees API), Modules 2 and 4 with heavier oil (18 API), Module 3 between them (22 API). Each module would eventually get its own platform, and each platform would be a piece of engineering at the edge of what was technically possible in the late 1990s.

The P-36 was a record-setter. At the time of her sinking, she was the world's largest semisubmersible production facility - a vast steel platform mounted on submerged pontoons, producing 84,000 barrels of oil per day and 1.3 million cubic meters of gas. She had started pumping in May 2000. Less than a year later she was gone. On the night of 15 March 2001, gas buildup in a ballast tank ignited. The first explosion damaged support columns; the second blew out emergency ballast systems. Workers from the overnight shift did not all get out. Eleven men died. The exact causes became the subject of investigations that reached into the procedures of the entire Brazilian offshore industry, and Petrobras lost a platform worth roughly $500 million before it had recovered a fraction of its costs.

Production had to continue. The next platform, P-52, was contracted in December 2003 to a consortium of Technip and Keppel FELS at a total cost of approximately $1 billion. It came online in November 2007. A second platform, P-54, was a floating production, storage, and offloading vessel converted from an enormous oil tanker called Barao de Maua. The conversion ran $628 million with Jurong Shipyard, with another $25 million going to Aker Solutions for processing equipment. P-54 weighed 66,224 tonnes - one of the largest FPSO vessels in the world - and began operating in December 2007. By late 2008, Module 1 and Module 2 together were producing 460,000 barrels a day. Module 3 added platform P-55. Module 4 followed. The field was developed not as one colossal project but as an expanding fleet of steel islands anchored above the reservoir.

Roncador forced the industry to invent. The field involved the world's first drill pipe riser rated for 2,000 meters of water depth, the first subsea tree at that depth, the first early production riser (EPR) qualified for those pressures. Offshore operations at 1,500 to 2,000 meters had been considered frontier territory a decade earlier. Brazil was about to make it routine. Petrobras ran 53 production wells and 29 water injection wells across the field, using long horizontal wellbores to pull oil from reservoirs that might spread for kilometers beneath a single surface platform. The technical papers from the Roncador development became a kind of textbook for deepwater drilling worldwide. Every platform, every riser, every subsea tree was an experiment that worked.

From a cruising altitude, the Roncador field is invisible most of the time - lost in the haze of the South Atlantic. But on clear days, four bright points of light appear on the water, pinpricks surrounded by tiny attending ships. They are the platforms, and the ships are the supply boats, the shuttle tankers, the guard vessels that ring each operation. An oil field from 33,000 feet is a constellation, not an object. The Roncador constellation produces hydrocarbons that power Brazil and the world, and it sits above the wreck of the P-36, which now rests 1,360 meters below the waves. Divers have visited her. The eleven men who died there are remembered at a memorial at Petrobras headquarters in Rio de Janeiro. The ocean keeps what it takes.