BHP Billiton announced today that the Mad Dog South (826-5) appraisal well and sidetrack, drilled and operated by BHP Billiton, had encountered significant hydrocarbon bearing reservoir. The 826-5 well is located on Gulf of Mexico Green Canyon block 826 approximately 100 miles (160 kilometers) south of Grand Isle, Louisiana, in approximately 5,100 feet (1,554 meters) of water. The well encountered 280 net feet (85 meters) of hydrocarbons in the objective, Miocene, hydrocarbon bearing sands. The subsequent sidetrack reached a total measured depth of 27,143 feet and discovered an oil column of more than 2,200 feet (670 meters).

The results from this well continue the successful phased development of the Mad Dog field and build upon the success of the A-7 well which came online in February 2008 in the western part of the field and encountered more than 2,500-foot (762 meter) hydrocarbon column, and 275 feet of net pay (84 meters).

J. Michael Yeager, Chief Executive, BHP Billiton Petroleum, said the exceptional result is a further positive step forward in BHP Billiton’s goal to build an increasingly material business in the Gulf of Mexico.

“The Mad Dog South well results indicate a significant opportunity for further field development. We are also very proud of our drilling team as they continue to demonstrate BHP Billiton’s ability to safely and successfully execute complex work plans in a technically challenging environment.”

The Mad Dog facility began production in January 2005 from Green Canyon Block 782 located approximately 120 miles off the Louisiana coastline. The facility has a nominal capacity of 80,000 barrels of oil per day.

BHP Billiton holds a 23.9 percent working interest in Mad Dog. While BHP Billiton was the designated operator for the purposes of drilling the Mad Dog South well and sidetrack, BP is the field operator with a 60.5 percent working interest.