TAPS: A step toward reducing U.S. dependence on foreign oil

In the summer of 1968, Atlantic Richfield established commercial oil production on Alaska’s North Slope with the Prudhoe Bay State No. 1 well. By January 1972, approximately 15 Bbbl of proven reserves had been identified at Prudhoe Bay. Estimates put Alaskan oil reserves at 100 Bbbl, far beyond known U.S. reserves at that time. The major obstacle to large-scale development was the difficulty of transporting oil at an economical cost to markets in the south. Although plans for a pipeline across Alaska had been proposed in 1968, the U.S. Department of the Interior would not authorize the project.

Extensive debate surrounded the pipeline issue in Congress. Environmentalists prevented the plan’s approval by publicizing its potential risks. However, the Arab Oil Embargo of October 1973 startled Congress and influenced public opinion in favor of a new domestic oil source. President Richard Nixon signed the Trans-Alaska Pipeline Authorization Act on Nov. 16, 1973, which granted a federal right-of-way for a pipeline.

Fig. 1. Location of Trans-Alaska Pipeline System.

Once approval had been secured, Alyeska Pipeline Service Company, a JV between Atlantic Richfield, Humble Oil and British Petroleum, and four other oil producers, commenced construction on a 414-mi road, on April 29, 1974. The road would cut across Alaska and connect the town of Fairbanks in the state’s southern portion with Prudhoe Bay, near the oil fields in the north.

ROUTE PLANNING/SURVEY

Alyeska engineers were tasked with designing and supervising construction of the Trans-Alaska Pipeline System (TAPS). Geological sampling and survey work were conducted to determine the pipeline’s best path. Using aerial photography, planners laid out a route that was subsequently staked by survey parties in the field, Fig. 1. The pipeline’s construction would be one of the first large-scale projects to deal with permafrost, and special construction techniques had to be developed to cope with the frozen ground. The 800-mi path, between Prudhoe Bay and Valdez, also required the design of an elevated pipeline. The 420 mi of above-ground segments required the steel pipe to be insulated, since extremely cold temperatures would cause the metal to become brittle, even when pumping hot oil through the pipeline.

TAPS also required pumping stations to drive oil through the pipeline to its destination in Valdez. Pump Station 1 would be positioned at the northernmost location, with 10 other units spread across the pipeline’s length. Each station would have four separate natural gas- or liquid-fueled turbines that pump a maximum 2.14 MMbopd.

CONSTRUCTION COMMENCES

Fig. 2. The pipeline zig-zags to allow for expansion or contraction.

On March 27, 1975, construction of the pipeline began, when workers buried the first section beneath the Tonsina River. The 48-in. pipeline would be built in a zig-zag configuration, to allow for expansion or contraction of the pipe because of temperature changes, Fig. 2. It would have to navigate multiple geographical anomalies, including 30 major rivers, road crossings and mountain passes. Where the Denali fault is exposed at the surface, the pipeline would be placed on sliders, to allow it to shift, if the fault became active. Construction workers endured long hours, cold temperatures and brutal conditions. Engineers had to address a wide range of difficulties, stemming mainly from the extreme cold and the difficult, isolated terrain. When constructing the pipeline through Atigun Pass (4,739 ft), Keystone Canyon, and near the Sagavanirktok River, workers were forced to improvise, creating specialized techniques to solve unforeseen problems. Work on the pumping stations and the Valdez Marine Terminal began in the autumn of 1974. This allowed work on those two projects to proceed during the winter, when pipe-laying was suspended, due to the frozen ground.

At the end of 1976, the pipeline project was 98% complete, the pump stations were 92% finished, and the marine terminal stood at 83% done. Because the terminal was the lagging portion of the project, its full work crew continued operations through the winter and into 1977.

PIPELINE FILLS WITH OIL

On June 20, 1977, the first section of pipeline was pressurized with nitrogen, and oil was introduced behind it. Because of the cold temperature, it took 31 days for oil to travel from Prudhoe to Valdez. The first oil arrived in Valdez on July 22, 1977. The start-up process and construction came to an end on Aug. 1, 1977 when the tanker, ARCO Juneau, sailed out of Valdez with the first load of oil from TAPS. The final construction cost of the pipeline and Valdez Marine Terminal tallied $8 billion. The construction effort also took the lives of 32 Alyeska and contract employees, who died from causes related directly to construction. 

About the Authors

Craig Fleming

World Oil

Craig Fleming Craig.Fleming@WorldOil.com