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Providing coverage of Alaska and northern Canada's oil and gas industry
November 2022

Vol. 27, No.48 Week of November 27, 2022

This month in history: 7.9 earthquake shuts down pipeline Nov. 3

20 years ago this month: Pipeline flowing again Nov. 6; temporary supports under areas affected, work on permanent repairs ongoing

Kristen Nelson

Petroleum News

Editor’s note: This story appeared in the Nov. 10, 2002, issue of Petroleum News Alaska

The trans-Alaska oil pipeline, shut down Nov. 3, 2002, after a 7.9 magnitude earthquake, was restarted shortly after 8 a.m. Nov. 6 and by that afternoon was once transporting crude oil from the North Slope at a rate of 750,000 barrels a day.

Alyeska Pipeline Service Co., which runs the pipeline for its owners, said shippers could begin loading oil at the Valdez Marine Terminal by the afternoon of Nov. 7.

Alyeska said that work on repairing damaged sections of the pipeline continues, but all priority work tasks were completed prior to restart. The company said that by the afternoon of Nov. 5 almost all of the critical tasks had been completed and crews would work through the night to finish the final tasks for a Nov. 6 restart.

Some flow began Nov. 5, when Alyeska used oil stored in tanks at pump station one to fill a portion of the pipeline Nov. 5, to make room for oil coming in from North Slope producers and also began pumping a limited amount of oil, some 3,000 bpd, to the Williams refinery in North Pole. At that time, 75 percent of projects deemed critical to startup had been completed.

The quake occurred at approximately 1:12 p.m. (Alaska standard time) Nov. 3 on the Denali fault in Interior Alaska some 45 miles east-northeast of Cantwell. Alyeska said Nov. 4 that one tanker had been loaded out of Valdez since the earthquake and the oil inventory, already low at the time of the quake, has been depleted.

The company said it would take some 24 hours after the restart of the pipeline for tanker loading to resume.

By Nov. 5, officials at the state-federal Joint Pipeline Office told PNA, there were five tankers stacked up waiting to load.

Two crossbeams breaking worst-case scenario

The senior federal and state officials at the JPO, Jerry Brossia, authorized officer for the U.S. Department of the Interior’s Bureau of Land Management, and John Kerrigan, state pipeline coordinator with the state Department of Natural Resources, said Nov. 5 that what happened to the pipeline Nov. 3 was exactly what was supposed to happen.

“This is a real success story,” Brossia said. For the last several years Alyeska has gone through the entire system and updated everything, he said, even doing a lot of structural work along the pipeline.

When the quake hit, the pipeline support system did “exactly what it was built and designed to do,” Brossia said. “It broke as predicted.” The worst case projected was for a magnitude 8 earthquake on the Denali fault: crossbeams were projected to break with the pipe remaining intact: “That’s what happened,” he said.

Kerrigan also said the quake demonstrated the success of the design of this pipeline: It “sheared according to design,” he said, adding that the pipeline was engineered to allow for movement of the pipe.

In this area close to the fault, Brossia said, the pipeline was designed to move on its supports: 20 feet horizontally and five feet vertically. The actual displacement was seven feet horizontally and two feet vertically, he said.

Brossia said oil spill contingency crews would be standing by during startup.

Monitoring system responded

Alyeska said the pipeline’s earthquake monitoring system responded to the quake and immediately began the process that would automatically shut down the pipeline. Before the alarm triggered the automatic shutdown, Alyeska personnel responded to the alarm and initiated a manual, controlled shutdown of the pipeline beginning at approximately 1:50 p.m.

Helicopter crews began aerial surveillance immediately and ground crews were mobilized to begin inspection of the integrity of the line. No leaks were detected and there was no apparent damage to the integrity of the line, Alyeska said, but pipeline support structures near milepost 588 were displaced during the quake. Portions of the vertical support members displaced were the “shoes” which allow the pipeline to slide along the crossbeams in between the vertical supports. Alyeska said that at eight locations there are “shoes” on the ground and at five locations there are crossbeams on the ground. Shoes and crossbeams are part of the support assembly for above-ground pipe.

Cribbing, engineering assessments

Alyeska said crews were on site Nov. 4 applying temporary supports for above-ground pipe in the milepost 588 and milepost 589 areas. The company was also doing engineering assessments of the pipeline, pipeline bridges and other supporting structures.

In an update issued at 6:30 p.m. Nov. 4, Alyeska said:

Two sections of the pipeline have been pressure tested and no leaks detected in those sections.

Cribbing for temporary support has been placed under the pipe near milepost 588 and crews were preparing to place temporary support under the pipe south of milepost 588.






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