By Margaret Bauman
Alaska Journal of Commerce

A high-tech system designed to detect oil spills in the sophisticated pipeline systems of Prudhoe Bay did not alert North Slope operators to a significant pipeline leak that was ultimately discovered by Slope workers traveling along the line.

The system is geared to detect catastrophic leaks, according to North Slope operator BP Exploration (Alaska) Inc.

"It is accurate down to 1 percent loss, under (state) regulatory requirements, and we set our own internal standard down to one half percent to be more sensitive, but there is a possibility that a leak could be smaller than that threshold and would not have been picked up," BP's Daren Beaudo said March 7.

Officials investigating the spill don't know yet whether the system detected the leak, "and that is an important part of the investigation," he said. "We will go back and pour over that data and try to get to what happened.

"It is a significant spill," Beaudo said. "We don't know what the volume is yet, but our commitment is to clean up whatever is spilled. We should have better estimate in a couple of days."

There are ultrasonic meters on either end of the pipe, and the system is designed to capture the flow rates and determine if there are any anomalies, Beaudo said.

Since flow rates vary, the system tries to sense what is real and what are blips in production rate, so there are different levels of calibration, he said.

Now, in the aftermath of the spill discovered by BP employees on the morning of March 2, officials will go back and look at all the data from the detection system, and cross-reference it against what will ultimately be recovered, allowing more to be known about how that system performs, Beaudo said.

The leak detection system is just one safeguard in place, Beaudo said.

"It takes multiple systems," Beaudo said. "We don't just rely on the leak detection system."

Oil companies have employees driving by the pipeline daily, "to keep their eyes and senses open to the surroundings," actually looking and sniffing for leaks, he said. Aircraft also periodically fly over the pipeline with infrared sensors, allowing observers to spot hot oil even when covered with snow. "That's how we got a jump on delineating the size, or footprint, of this spill," he said.

In the investigation of the spill now under way, there will also be a determination of how well the detection system worked and whether is needs to be fine tuned, he said. "If we need to make adjustments, we will."

Margaret Bauman can be reached at margie.bauman@alaskajournal.com.