Extension vaults Mad Dog to rival Thunder Horse

A successful appraisal well in a previously untested northern segment of Mad Dog field in the US Gulf of Mexico has hiked the complex’s resource to as much as 4 billion bbl of oil equivalent in place, rivaling that of Thunder Horse, said BP PLC.

Still, BP said, the results of the appraisal well on Green Canyon Block 738 must be confirmed with even more appraisal drilling. The 4 billion boe figure includes the existing field, in production since 2005, and 2008-09 appraisal drilling of Mad Dog South field, BP said.

BHP Billiton Petroleum drilled the northern extension well on behalf of unit operator BP in 4,500 ft of water 140 miles south of Grand Isle, La. It cut 166 net ft of hydrocarbons in the objective Miocene hydrocarbon-bearing sands and discovered an oil column of more than 300 ft.

As a result of the substantial Mad Dog South finds in 2009, BP has been advancing development options to increase output from Mad Dog by adding another spar production facility with a capacity of 120,000-140,000 boe/d, said Bob Dudley, BP Group chief executive.

“With these additional hydrocarbon resources north of the main field, Mad Dog has been firmly established as a giant field in BP’s Gulf of Mexico portfolio,” Dudley said.

BP has a 60.5% working interest in Mad Dog, BHP Billiton has 23.9%, and Chevron through its Union Oil Co. of California subsidiary has 15.6%.