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Some Prudhoe wells idled after pipe bursts
A pipeline leak on the afternoon of April 10 prompted BP to shut-in some wells at drill site 1 in the eastern operating area of the Prudhoe Bay oil field.
The production impact was limited, within the range of daily fluctuations normally seen in overall North Slope output, BP Alaska spokesman Steve Rinehart told Petroleum News.
The failed pipe was an above-ground, 8-inch seawater injection line running between a manifold building and well 11 at drill site 1. The drill site was among the earliest installed at Prudhoe Bay, the nation’s largest oil field.
Because the well had been shut-in for servicing, the pipeline was filled with freeze protection fluids, Rinehart said. The fluids consisted of about 60 percent methanol and 40 percent seawater.
The pipeline failure occurred “during a well warm up procedure conducted in preparation for a mechanical integrity test on Well 11,” said a situation report from the Alaska Department of Environmental Conservation.
3,675-gallon spill Field workers were moving seawater into the line and noticed pressure at the manifold but not at the wellhouse, Rinehart said. Then they saw fluids spraying from the pipeline.
The burst pipe, as well as an adjacent line, dislodged off the rack elevating them above the ground, the DEC’s John Ebel said.
No one was injured in the incident.
Several wells were shut-in as a precaution, Rinehart said.
Well 11, formerly an oil producer, now serves as an injection well to send seawater into the Prudhoe Bay reservoir to help enhance oil recovery.
BP estimated the spill at 3,675 gallons, based on the engineered volume of the 8-inch line between the manifold building and well 11, the DEC said. Aside from methanol and seawater, a small amount of crude oil also spilled, the agency said.
The fluids were released onto the snow-covered gravel drill pad and flowed into a reserve pit, the DEC said. Responders surveyed a contamination area of about 3.85 acres.
BP worked to remove contaminated snow, ice and gravel. The pipeline was blocked and blinded at the manifold building and at the well.
The company was looking into what caused the leak, such as ice perhaps plugging the line despite freeze protection.
—Wesley Loy
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