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Neptune well hits pay dirt Gulf prospect shaping up as major discovery with 500 feet of net oil pay Petroleum News Staff-Houston
The Gulf of Mexico’s deepwater Atwater Foldbelt may have another big winner in Neptune, originally a marginal discovery that turned up a hardy 500 feet plus of net oil pay on its fifth well.
In terms of size, the jury is out until after completion of a sidetrack off the Neptune-5 appraisal well. Nevertheless, the owners wasted no time pumping up the discovery in prepared remarks released Aug. 8.
“The well logs at Neptune-5 indicate thick sands and are amongst the most impressive we’ve seen in the Gulf of Mexico,” said Philip Aiken, chief executive officer of Neptune operator BHP Billiton.
Phil Behrman, senior vice president of worldwide exploration for Neptune partner Marathon Oil, said the Neptune-5 well “clearly improves the potential commerciality of this discovery.”
Neptune-5 encountered more than four times the oil pay than in the last successful appraisal well, Neptune-3, and is said to be situated in a hydrocarbon column measuring 1,200 feet. If the discovery proves to have body, it certainly could hold far more reserves than pre-drill estimates of around 100 million barrels of oil equivalent.
“Previous gross reserve potential of 100 million barrels is likely to be revised significantly upward based on the new results,” concluded Banc of America Securities in a report to investors.
Neptune-5, on Atwater Valley Block 574, was drilled into Miocene-age sands to a total depth of 19,142 feet. It went down between and down drip of the Neptune-1 and Neptune-2 wells. Neptune in same trend as Atlantis, Mad Dog Covering several blocks, the Neptune prospect is east and on the same prolific Atwater Foldbelt trend that gave rise to the Atlantis and Mad Dog discoveries, among the largest in the Gulf with combined estimated reserves of 800 million to more than 1 billion barrels of oil equivalent. Both BP-operated fields are scheduled for development.
In a finding that could help establish another geological link between Neptune and the more well documented Atwater Fold discoveries, the latest well produced fluids that point to the presence of oil similar in quality to the medium sour crude found at Atlantis and Mad Dog, BHP said.
BHP holds a 35 percent stake in Neptune, as well as a 44 percent interest in Atlantis and a 23.9 percent interest in Mad Dog. Marathon has a 30 percent interest in Neptune, followed by Woodside Petroleum with 20 percent and Maxus Exploration, a Repsol YPF subsidiary, with 15 percent.
The original Neptune discovery was made in 1995, but the prospect for commercialization remained in doubt. During the first half of 2002, BP took an $85 million writedown on the Neptune and relinquished its 57.5 percent interest in the discovery to BHP, which then brought in Marathon and Woodside.
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