Chevron and Hess have started crude oil production from the Tubular Bells deepwater project in the Gulf of Mexico.
The project is expected to produce 50,000 barrels of oil equivalent per day from three wells.
The field is 135 miles southeast of New Orleans in 4,300 feet of water in the Mississippi Canyon area and was discovered in 2003.
Diamond Offshore Drilling has won a number of long-term charter contracts from US independent Hess for a pair of drillships.
The Houston-based company also announced plans to retire and scrap six of its mid-water submersible rigs, including the Ocean Epoch, Ocean New Era and Ocean Whittington.