Trans-Alaska Pipeline to shutdown for portions of summer for maintenance

Alyeska Pipeline Service Co. and the North Slope producers have their normal annual maintenance projects underway on the Trans Alaska Pipeline System and the big oil processing plants on the North Slope.

These plant “turnarounds” can be quite engineering and labor-intensive, and can involve large numbers of people.

This summer, Alyeska is planning three maintenance shutdowns of the TAPS between June 15 and July 6, a company official said. TAPS is an 800-mile, 48-inch pipeline connecting North Slope oil fields with the Valdez Marine Terminal in southern Alaska.

Each shutdown will last 12 to 18 hours, Alyeska spokeswoman Michelle Egan said. Projects will include replacement of six-inch bypass valves and spool of a mainline check valve; enhancing a safety integrity pressure protection system; preparation for an inline inspection of the pipeline that will begin this fall, and conducting an annual inspection and maintenance at the Pump Station 9 power substation.

“These line-wide shutdowns provide maintenance crews with the time and opportunity to work on coordinated projects along the pipeline and at the Valdez Marine Terminal while the pipeline is not in its regular operating state,” Egan said.

Meanwhile, the major North Slope producers are planning their own major facility maintenance and these are typically scheduled to coincide with the TAPS shutdowns.

At Prudhoe Bay, the North Slope’s largest producing oil field, Dawn Patience, spokeswoman for BP, the operator, said her company, “has normal planned maintenance this summer, focused on piping replacements, facility maintenance, vessels repairs and other improvements.”

ConocoPhillips Alaska spokeswoman Natalie Lowman said her company is planning major maintenance work and a shutdown in mid-June at the Kuparuk CPF2 facility in the Kuparuk River field, west of Prudhoe Bay.

The company is also planning a major maintenance shutdown at the Alpine field beginning in mid-July, Lowman said.

Alpine, near the Colville River delta, is the farthest west producing field on the slope. ConocoPhillips is operator at both the Kuparuk River and Alpine fields.

When the maintenance shutdowns happen oil production is curtailed sharply for the month, which cuts into revenues being paid to the state treasury. North Slope production has averaged 515,140 barrels a day through June 7, a volume comparable to the same period of June, 2017, according to state Department of Revenue production data.

But the daily production will drop off in late June and periods of July when facilities including TAPS are temporarily shut in for maintenance. To some extent producers are able to store oil on the North Slope during periods when the pipeline is shut down, so the producing wells themselves are usually not taken out of service.

The annual maintenance on TAPS and the North Slope plants is what enables the system to be extended in its operating life, at least for the machinery. The pipeline and slope plants have been operating for more than 40 years and with proper maintenance the system can be extended almost indefinitely, as long as the oil is there.

Metal in the pipeline and plants can last a very long time if it is inspected for corrosion, which is done regularly. The moving parts, the machinery in process plants, pump stations, gate valves, or at the Valdez Marine Terminal, will wear down over time and need to be replaced. Alyeska and the slope operating companies are quite diligent about this, and the work planned this summer reflects that.

The longevity of the pipeline and the North Slope oil fields is more a question of economics than physical durability, as long as proper maintenance is done. One focus for the TAPS owner companies, which are mostly the slope producers, is replacing obsolete facilities with upgrades that incorporate new, more efficient technologies. The upgrades to TAPS pump stations in recent years are examples of this.

There was real concern for the future during the years that slope production was declining steadily at rates averaging 6 percent a year. Had that continued the pipeline’s average annual “throughput” would have dropped in about 10 years from its current 515,000 barrels per day to around 300,000 barrels per day, which many consider a possible economic threshold for TAPS.

However, North Slope production has stabilized over the last three years and even increased slightly thanks mainly to new projects brought on line by the producing companies. With a number of new discoveries being made, state officials believe it’s likely the current volumes moving through TAPS can be maintained for at least the next decade.

If large new discoveries are made in places like the Arctic National Wildlife Refuge or the offshore Outer Continental Shelf, the volumes moving through TAPS could even increase.