Unocal Corporation met its aggressive target of reducing deepwater drilling costs by fifty percent on the first exploratory well it drilled in Garden Banks Block 551 in the deepwater Gulf of Mexico. The well was drilled using Transoceanís, semisubmersible, Transocean Richardson at a drilling rate of 479 feet per day. This compared to 206 feet per day for a comparable deepwater exploration well in the Garden Banks area. The well, South Sierra, was spudded on April 6, and reached its final objective in thirty days.
The well was drilled in 3,674 feet of water to a total depth of 14,360 feet. The well encountered hydrocarbons in two separate intervals however, it does not appear to be a commercial discovery. Unocal has a fifty percent working interest on the South Sierra prospect.