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‘Structural anomalies’ delay Neptune in Gulf
Australia’s BHP Billiton, during a routine inspection just prior to the startup of the Neptune tension leg platform in the deepwater Gulf of Mexico, said it found “structural anomalies” in the hull, causing a delay in first oil and gas production that was initially scheduled to come on-stream by the end of March.
Neptune is the third high-profile deepwater U.S. Gulf project in the last two years to miss a scheduled startup due to unexpected subsea problems. BP announced a delay at its Thunder Horse development in August 2006, citing issues with leaks on manifold welds. Thunder Horse represents the largest-ever oil discovery in the Gulf, with reserves of around 1 billion barrels. Additionally, Chevron sidelined its Tahiti project last June, citing concerns about the shackles on mooring lines.
Further inspection under way BHP announced March 24 that further inspection and assessment of Neptune’s hull was under way “to determine the appropriate course of action to mitigate the anomaly.”
“The company is currently assessing all the options in order to re-commence startup activities,” the company added. However, BHP did not provide a new timeline for field startup.
As a safety precaution, BHP initially removed all personnel from the facility until it could assess the problem. Since performing “a rigorous analysis,” BHP said it “confirmed the facility was safe for crews to return to work and crews began boarding the platform March 24.”
Neptune is about 120 miles off the Louisiana coastline. It is a single-column tension leg platform and was installed in 4,250 feet of water on Green Canyon block 613. The Neptune field actually comprises five blocks: Atwater Valley 573, 574, 575, 617 and 618 where water depths range from 4,200 to 6,500 feet.
The Neptune tension leg platform is designed to handle 50,000 barrels of oil per day and 50 million cubic feet of natural gas per day. BHP is the designated operator of the field with a 35 percent interest. Partners include Marathon Oil Co. (30 percent), Woodside Energy (USA) Inc. (20 percent), and a subsidiary of Woodside Petroleum Ltd., Maxus (U.S.) Exploration Co. (15 percent).
—Ray Tyson
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