OTC: Alaska Oil Pipeline Still Goes with the Flow

Two major crude oil projects in development on the North Slope of Alaska will usher in the next era for the venerable Trans Alaska Pipeline System.

ConocoPhillips’ Willow Project and Australian oil company Santos’ Pikka are years away from producing, but will eventually feed into the durable conduit closing in on half a century of service.

The engineering marvel’s final weld was completed 46 years ago this month, meaning the pipe has been in service 26 years beyond its intended expiration date. Its design capacity was 2 MMbbl/d but TAPS transported 2.1 MMbbl/d at its peak in 1988. Current volumes have fallen to almost 500,000 bbl/d.

Thomas Marchesani, interim vice president of engineering, risk and system integrity for Alyeska Pipeline Service Co., began working on the pipeline in 1992. If he’s learned anything about it in the last 31 years, it’s that the design engineers were meticulous in their work.

“Over and over again, what I found was that the design engineers really nailed it,” he said during his opening keynote at the 2023 Offshore Technology Conference on May 1. “And when we would come upon something, we’d take a look at it and it wouldn’t make any sense and think, I don’t know what these guys were thinking, let’s change this.”

Whether it was an issue with condensers or routing, making changes tended to bring about a series of problems that the early engineers had anticipated and sought to avoid.

“When we came and fiddled around with it and went away from what they were doing, we most often had to revert back,” Marchesani said.

Getting it built

Not that the original design wasn’t flexible. The plan was to build 12 pump stations, but during construction it became apparent that only eight were needed. As throughput ramped up, two more were added. As production from the North Slope declined over the years, stations were shut down and dismantled.

Five berths for oil tankers were part of the construction plan at the terminus of the system, the Valdez Marine Terminal. Only four were needed. Eighteen storage tanks were built, with the ability to expand to 32. The expansion never happened and there are now 14 tanks in service.

Just getting the project built required navigating the new terrain of ferocious environmentalist opposition, much of it in reaction to a 100,000-barrel oil spill in the Santa Barbara, California, Channel in 1969. The first-ever environmental impact statement under the National Environmental Policy Act was prepared for TAPS. The 200-page report was rejected as insufficient and a 3,500-page report was prepared that was more comprehensive. Lawsuits to block the project on environmental grounds were filed anyway.

In 1973, TAPS acquired an unexpected ally: OPEC. The oil cartel’s embargo created an energy crisis that convinced enough politicians to clear the way to build the pipeline. A deadlocked vote on the authorization act in the U.S. Senate was broken by Vice President Spiro Agnew and construction could begin.

Unique challenges

The system had to adapt to its environment in ways others do not. A little more than half of the pipe is above ground so that hot oil moving through the pipe did not melt the thaw-unstable permafrost covering the Alaskan tundra. The elevated support system is called vertical support members (VSM). A passive thermal cooling system is incorporated into thousands of the members in addition to an active refrigeration system in parts of the line.

Changes continued over the years. After the Exxon Valdez supertanker hit a reef and spilled 260,000 bbl of crude into Prince William Sound in 1989, Alyeska established a system known as the ship escort response vessel system (SERVS). The system uses tugboats to guide tankers through the Valdez Narrows and prevent or respond to a spill quickly.

Challenges facing the system now include renewal of its 30-year right of way permit in 2034—a far more difficult task in the polarized political environment than in the 1970s.

The system must also absorb new volumes of crude from projects underway. ConocoPhillips’ Willow project is under construction following its approval by the Biden administration in March. When complete, the estimated $8 billion project is expected to produce 180,000 bbl/d. Santos’ $2.6 billion Pikka project is expected to begin production in 2026 and deliver 80,000 bbl/d.

The system also faces a threat from climate change. As higher temperatures melt the permafrost, engineers must grapple with VSMs standing on unstable ground.