BHP Billiton has spud the Neptune-5 appraisal well, located in the Gulf of Mexico in Atwater Valley 574 using the drill ship Glomar C.R. Luigs. Neptune-5 is a significant downdip stepout from the original Neptune-1 discovery well. The well seeks to establish the position of the oil-water contact in this part of the field.
BHP Billiton is the designated operator of the five-block unit with a 50-percent working interest. The other participants are Marathon Oil Company and Woodside Petroleum Ltd., which hold 30-percent and 20-percent working interests, respectively. The Neptune discovery is located in the Atwater Foldbelt region of the Gulf of Mexico. This area also includes the Mad Dog and Atlantis fields.