Bullets, flaring are Point Thomson concerns
Shots from hunters could pierce pipeline and gas burn-off could melt tundra, Alaska official says in review of ExxonMobil project
For Petroleum News
The Alaska Department of Natural Resources sees potential for a couple of quirky problems with ExxonMobil’s Point Thomson field development.
One has to do with stray bullets. The other concerns a really hot flame.
In comments submitted recently to the U.S. Army Corps of Engineers, which is preparing an environmental impact statement for the Point Thomson project, the DNR noted it wants to see how ExxonMobil plans to bullet-proof a new pipeline it will build to carry Point Thomson production.
And the DNR suggested that a proposed gas flare at the field might need to be higher off the ground to avoid damage to the tundra.
ExxonMobil is aiming to start producing 10,000 barrels a day of gas condensate by the end of 2014 from Point Thomson, a rich oil and natural gas field along Alaska’s Beaufort Sea coastline just west of the Arctic National Wildlife Refuge.
Stray roundsDon Perrin, DNR’s project management and permit coordinator, submitted the department’s comments to the Army Corps.
In an interview with Petroleum News, Perrin said the issue of stray bullets came up strongly at scoping meetings the Corps held in January in North Slope villages including Kaktovik and Nuiqsut.
Hunters from Kaktovik, which is on the Beaufort Sea coast inside ANWR, often travel west to the area of the Point Thomson development and shoot from boats at caribou on the tundra, Perrin said.
The worry of North Slope residents, he said, is that stray bullets could pierce a new 22-mile elevated pipeline ExxonMobil plans to lay along the coastline to feed Point Thomson production into an existing pipeline at the Badami field to the west.
“Exxon is trying to respond to the concerns,” Perrin said.
The options include beefing up the bullet resistance of the 12-inch pipeline, or moving the line farther inland, he said.
In an October 2009 project description submitted to the Corps, ExxonMobil wrote:
“The export pipeline route traverses local hunting grounds and, therefore, its design must consider the potential for accidental bullet strikes. The design will consider rifle calibers and ammunition typically utilized in the area for caribou hunting, and may incorporate additional wall thickness if required to prevent penetration from bullets fired from the coastline.”
Bullets can cause spillsPerrin, in his comments to the Corps, wrote that ExxonMobil had indicated in recent discussions that the pipe wall thickness would be increased to better resist bullet strikes.
Perrin suggested more information be provided about the revised design, but added: “ExxonMobil and the State should also take into consideration the need for confidentiality in publishing data on bullet impact resistance, as this is information describing how to create a pipeline rupture or breach.”
Alaskans know from experience that oil pipelines and bullets can be a bad combination.
In October 2001 a man with a high-powered rifle shot the trans-Alaska oil pipeline near the Livengood community about 80 miles north of Fairbanks. The bullet pierced the steel pipe and insulating jacket, unleashing a jet of oil into nearby woods.
An estimated 285,600 gallons of oil spilled over 36 hours before responders could seal the bullet hole amid worry the fine oil mist in the air might explode.
The drunken shooter, Daniel Carson Lewis of Livengood, was convicted on a variety of charges and drew a multiyear prison sentence.
The Point Thomson flareAnother issue Perrin raised with the Army Corps is the height of the elevated gas flare proposed for the Point Thomson field.
Such flares are commonly used around oil and gas fields to provide a safe way to burn off gases during maintenance or when process upsets or emergencies occur.
At 40 feet off the ground, the proposed Point Thomson flare might not be high enough to prevent heat transfer that could damage the tundra, melt the permafrost and liquefy nearby water bodies, Perrin told Petroleum News.
He noted that heat transfer from an elevated flare has been a problem at Alpine, a ConocoPhillips-operated oil field on the North Slope.
“Alpine’s flare is located along the river channel adjacent to a thaw bubble near the water’s edge,” Perrin wrote in the DNR comments to the Army Corps.
The Point Thomson project, which involves cycling gas to the surface for collection of condensate, is expected to “produce enormous volumes of gas” and may need to flare in the event of problems, Perrin wrote.
“As such, flaring and its environmental effects should be fully evaluated,” he wrote.
An environmental report ExxonMobil submitted to the Corps in November says a lower flare would be less visible in ANWR, and less noisy.
The company’s proposed flaring system actually would feature two flare tips mounted atop vertical risers. One would be about 120 feet up for high-pressure gases, with another about 40 feet high for low-pressure gases.
The low-pressure flare would be used most often.
“No routine flaring is planned at the Project site, other than the minor quantities of purge and pilot gas that are required for safe flare operations,” ExxonMobil wrote.