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replace the lines entirely. This provides operators
with the opportunity to modernize with pipes
made out of stainless steel or plastic; it also gives
them a chance to make these near-unpiggable lines
piggable.
Currently, all of these solutions are costly,
and they all require the use of highly specialized
equipment and personnel. Eventually, someone
will come up with a cost-effective “total
solution” to the problem of aging gathering lines.
Someday, there will be industry associations and
organizations that offer guidance and best practices
for gathering lines.
Until then, though, industry experts around
the globe will keep working to share information,
reduce risks, and eliminate incidents like the
Nefteyugansk leak.
Seeking Solutions on
Alaska’s North Slope
Located 400 km (250 mi) from the Arctic Circle and
1,900 km (1,200 mi) from the North Pole, Alaska’s North
Slope is home to the Prudhoe Bay oil field, the largest oil
field in North America. In Alaska, oil production accounts
for a staggering 90 percent of the U.S. state’s economy.
And, much like its counterparts in Siberia and Abu
Dhabi, the North Slope is also home to an infrastructure
that has exceeded its expected lifespan by several
decades.
The most highly publicized oil spill in the North Slope
was the 2006 Prudhoe
Bay oil spill, which resulted in the loss of an estimated 267,000 gallons of oil. The culprit:
A rupture in a 34-inch transmission line.
But the Prudhoe Bay spill overshadows a larger, more widespread problem. According to
the Nuka Research Group’s comprehensive November 2010 North Slope Spills Analysis,
the majority of the area’s spills involve gathering lines – not transmission lines.
“Spills from flowlines account for the highest total amount of oil spilled in the six
regulatory categories,” the report reads. “The average spill volume for flowlines is twice the
average of all spills.”
In other words, while accidents like Prudhoe Bay generate headlines, it’s the more frequent
– but less publicized – gathering line leaks that do most of the damage in the long run.
One reason for this is that gathering lines are older. And older pipelines are much more
likely to fail. According to the North Slope Spills Analysis, a 5-year-old pipeline had a mere
3.3 percent probability of leaks. On a 30-year-old pipeline, that probability jumped up
to 31 percent. Most gathering lines in the North Slope were built in the late 1960s. Their
expected lifespan at the time: about 15 years.
The analysis emphasized the need for an integrity management program (IMP), and it
recommended that Alaska adopt an IMP that regulates gathering lines like transmission
lines. This more proactive approach – combined with new technology designed to repair or
replace aging gathering lines – would help operators reduce risks and help curb costly and
damaging leaks.
30
yr old
pipeline
31%
risk failure
5
yr old
pipeline
3%
risk failure