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Low volumes complicate Alyeska operations Barrett tells Alaska Oil & Gas Congress pipeline can handle low-flow issues, but lower volumes mean higher chance of shutdowns Kristen Nelson Petroleum News
The trans-Alaska oil pipeline has been in operation for 34 years and it’s “a great asset,” “in pretty good condition” with “a great workforce,” Alyeska Pipeline Service Co. President Tom Barrett told the Alaska Oil and Gas Congress Sept. 20.
But, Barrett said, he wants more oil moving through the line, which was designed for 1.5 million barrels per day, peaked at 2.1 million bpd in the 1980s and has been in decline ever since, currently moving some 600,000 bpd.
The line averaged 700,000 bpd in its first year of operation, Barrett said. With throughput below where the line started, “you’re in kind of new territory every day.”
That presents operational difficulties, Barrett said, comparing it to running a car at 15 miles per hour instead of its 45-60 mph optimal speed.
Alyeska invested $10 million in a two-year low-flow study completed earlier this year, available on Alyeska’s website (www.alyeska-pipe.com), addressing the implications for the pipeline operator, he said.
Velocity and temperature “There are two issues … one is velocity and one is the temperature,” Barrett said. “It used to take four days to move a barrel of oil from Prudhoe Bay down to Valdez to the terminal. Right now it takes about 15,” but if rates drop to 200,000 bpd, he said, it will take a month.
Oil goes into the line at above 100 degrees; right now, depending on ambient temperature, it is about 40 degrees when it reaches Valdez.
If the temperature in the line drops below freezing, water in the oil falls out and ice starts to build up. There isn’t much water in the oil, he said, but there’s always some. If ice builds up, especially at low points in the line, that ice could move into strainers and pumps, causing problems.
“We get more wax settlement as the flow declines,” Barrett said, which creates problems because it increases the risk of corrosion, even though Alyeska scrapes the line for wax regularly.
Those are among the problems Alyeska has to handle with reduced flow through the line, and “individually they can be managed … together they really compound,” he said.
Risk of shutdowns Barrett said it isn’t the risk of leaking oil, but the risk “that we will be shut down more to address these problems.”
Because of wax due to lower flow, Alyeska runs more pigs to get the wax out.
Alyeska had a shutdown in January and “part of the startup issue is we had pigs in the line,” and when you start up after a length of time, you push wax and ice, whatever is in the line, “towards your strainers and your pumps. And if you take out a mainline pump with that type of stuff you’re going to be down … for a long while,” he said.
So you run more pigs to address the wax issue, “solving one problem and increasing the risk on the other side.”
“Figuring that out, whether we’re adding launchers-receivers, or just the type of pigs we run, is complex — it’s complicated petroleum pipeline engineering. You have people that can do it, but it is a challenge,” Barrett said.
Increasing the flow If you increase the flow to the million-barrels-a-day target set by the governor, “a lot of these problems fall off from an operating point of view,” he said.
Barrett said he believes “we’re a couple of years behind” where we should be on getting more oil in the line.
When Alyeska started its low-flow study in 2008, the projection for 2011 was 700,000 bpd.
“We’re seeing 600,000 barrels,” he said, adding that he worries that there isn’t the urgency needed to get additional barrels into the line.
The resources are there, the infrastructure is there, so what’s stopping Alaska from moving a million bpd, he asked.
“Two things: political will … political will in Juneau; political will in Washington.”
“I actually think that’s the obstacle to turning this dynamic around and allowing us to operate better in the future.”
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