TAPS' reduced flow to reflect N.
Slope decline
Republished with permission from
Oil & Gas Journal, June 10, 1996, p.30. Copyright retained by Pennwell Publishing.
Further reproduction, without the express permission of Pennwell Publishing is expressly
forbidden.
PennWell Publishing Company
Tulsa, OK 74101
Alyeska Pipeline Service Co. plans to place
on standby two of the 10 pump stations on the Trans-Alaska Pipeline System (TAPS) July 1
due to declining North Slope production.
The 800 mile pipeline has moved more than
11 billion bbl of crude since it was completed 19 years ago. At its peak, 2.1 million b/d
flowed from the North Slope to a tanker terminal at Valdez.
Alyeska plans to put Pump Station 8, just
south of Fairbanks, and Pump Station 10, north of Glennallen, in standby status. It can
return them to full service within 6 months if necessary--even faster in case of
emergency.
Pump Station 7, which is off line for
maintenance and modification, will be returned to service before Stations 8 and 10 are
idled.
Roger Staiger, Alyeska's Washington
representative, said "The company continues to look for efficient, streamlined
operating changes that will keep North Slope crude oil competitive on the world oil
market. This, in turn, will lead to a longer life for the trans-Alaska pipeline."
System throughput
TAPS originally was designed for a maximum
throughput of 2 million b/d using 12 pump stations.
Although pump station numbers run from 1 to
12, Station 11 was not built and Station 5 is a pressure relief station on the south side
of the Brooks Range which has no main line pumps.
Development and injection of a drag
reduction additive (DRA) enabled the pipeline to exceed capacity and move more than 2.1
million b/d in 1988 using all 10 pump stations. DRA consists of long chain polymers that
reduce turbulence within the oil flow and friction between the crude and pipe wall.
Under a new operating plan, Alyeska will
inject DRA at Stations 7 and 9.
Baker Pipeline Products Co. makes the
DRA Alyeska uses.
Current North Slope production and TAPS
throughput is about 1.5 million b/d.
TAPS will have a capacity of 1.7 million
b/d using eight stations. Alyeska plans to keep line capacity at 200,000 b/d more than
projected North Slope production so oil output won't be constrained.
Alyeska said it may idle Stations 2 and 6
in 1997 and Station 12 in 1998 if North Slope throughput continues to decline as
predicted.
TAPS is regulated by the Joint Pipeline
Office (JPO), which consists of representatives of Alaska's Natural Resources and
Environment Conservation departments, and the federal Bureau of Land Management, Office of
Pipeline Safety, Environmental Protection Agency, and U.S. Coast Guard.
Although Alaska does not need JPO approval
to close stations 8 and 10, it does need approval to remove and transfer personnel that
are part of oil spill prevention and response plans.
It will maintain the piping at the two
stations to Transportation Department requirements. Cathodic protection on piping will
remain active. Most electronic communication gear, control equipment, pumps, and heaters
will remain in place. Delicate equipment and the jet engines and reaction turbine that
drive the pumps will be moved. Security will be maintained at the closed stations.
Pump Stations 8 and 10 have collocated
topping units that provide diesel fuel for the dual 15,300 hp pumps and motor vehicles.
Station 8 stopped fuel production last May, and Station 10 will do likewise when it is
closed.
Leak detection
Separately, Alyeska told the JPO it will
install probes to ensure there are no leaks at 40 valves along the line.
That was in response to a leak north of
Glennallen that released about 20,000 gal of crude onto the ground. The leak, caused by a
loose plug, was found after a worker noticed oil in a nearby manhole.
Crews have almost completed cleanup of soil
at the site. No significant environmental damage occurred.
Alyeska also said it will consider
expediting a 5 year program to excavate and examine the buried valves.
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