The pipes in the Jubarte field, 77 kilometers (48 miles) off the coast from the state of Espiritu Santo, plunge 4.4 kilometers down, through water, sand and -- most problematically -- through a salt layer 100 meters thick.
The salt layer is the biggest obstacle to exploiting other fields in a zone hundreds of kilometers farther offshore that are estimated to contain enough oil to triple Brazil's current proven reserves of 14 billion barrels.
That new oil find lies some seven kilometers down, through salt estimated to be a kilometer thick.
Salt is a challenge to oil companies because it constantly moves and exerts pressure, creating a risk of broken pipes and demanding innovative extraction technology.
A platform owned by Brazil's state-run monopoly Petrobras will pump an estimated 10,000 to 15,000 barrels of oil a day from the Jubarte field.