Ken Sheffield, president of Pioneer Natural Resources Alaska, told Petroleum News in July that the new Arctic Fox No. 1 rig under construction for his company’s use will employ proven technology to cut exploration drilling costs on Alaska’s North Slope.
“This rig is very, very similar to rigs that are used in the Canadian Arctic for exploration,” Sheffield said. “The rig design is proven. It’s just a new application for the North Slope.
“What we’re trying to do is drill more wells per season and spend time drilling wells and less time moving and building ice.”
A joint venture between Doyon Drilling Inc. and Akita Drilling Ltd. is building the rig in Nisku, Alberta, for use in next winter’s exploration season. A team of Pioneer, Doyon and Akita personnel specified the rig design.
“They tried to draw on the experience of all of the personnel in those three companies to design this rig,” Sheffield said. “… It is a fit-for-purpose rig, designed to drill exploration wells on the North Slope of Alaska.”
Lightweight design
The rig’s lightweight design involves a 400,000-pound rated double mast that reduces the derrick height to about two-thirds that of a typical triple-mast North Slope rig; the double mast derrick handles two joints of drill pipe rather than the three joints of a triple mast derrick. The double-mast configuration is suitable for exploration drilling where long lateral well are not required, Sheffield said.
“It’s very common onshore … to drill with a double,” Sheffield said.
Using 4-inch or 4.5-inch drill pipe, the new rig will drill routinely to 10,000 feet and could drill to 12,000 feet, depending on the casing and well bore designs, he said.
In fact the rig’s design team considered several pipe diameter options for the type of exploration work that Pioneer anticipates — the team determined that relatively small diameter piping would achieve an effective balance between rig size and well depth.
“Five inch was for a long time the standard across the slope,” Vance Hazzard, Pioneer’s Alaska drilling superintendent, said. “(4 inch) works out great for the hole sizes that we’re looking at.”
Truckable modules
The rig can break down into many small modules for easy portability — an in-line layout design coupled with a telescoping mast helps allow the rig to split into 35 individual loads, each of which will fit onto a conventional truck. The rig is highway transportable and could be moved to places in Alaska with road access during the summer, Sheffield said. Even on the slope the new rig will prove much more mobile than the large development-oriented rigs that have characterized North Slope drilling, he said.
“This rig will move in loads of approximately 100,000 pounds which is considerably lighter than the existing rigs on the slope,” Sheffield said. “(The existing rigs), they’re quite mobile if they’re on a gravel pad moving a short distance to drill the next well. But if you try to take one of those rigs and move a long distance they’re quite heavy and relatively time consuming to move.”
Less ice road construction
A reduction in the need for heavy-duty ice roads should also prove to be a big pay off in the use of the new rig.
“We are confident that this lighter rig will require considerably less ice construction because of the much lighter loads,” Sheffield said. “… Considerably less ice is required to support 100,000 pounds than is required to support 1.5 million pounds (for a development rig).”
Also the rig will not require the same road width as a conventional North Slope rig.
“The other thing is that the North Slope rigs are all much wider — they’re set up for 30 to 35-foot wide roads and in general we can get by with as little as 16 to 20-foot road,” Hazzard said.
What’s more, the trucks carrying the rig modules will be able to cross the tundra on snow roads, Hazzard said. Snow roads don’t need water to make ice and are quicker and cheaper to build than ice roads.
We’re working through a snow road concept that uses densified, processed snow, Hazzard said. Using a truck “the densified snow has enough strength to keep you off the tundra,” he said.
Even over water, where ice roads will still be necessary, the loads will not require the same thickness of ice that a conventional rig needs. A typical development rig would require 7 or 8 feet of ice to go over a flowing river or over sea ice — for our load we would be looking at 4 feet, Hazzard said.
“And we have much more flexibility with the road layout than you do with the large rigs,” he said. A development rig needs a very wide road without much slope but a truck can handle bigger grades and go round sharper curves, he said.
Multiple wells per season
Simplified road construction and the ability to move the rig quickly will enable Pioneer to drill multiple wells in a single winter season. And, given the fixed costs inherent in mobilizing a rig for a drilling season, drilling multiple wells will translate directly into less cost per well.
“We’re hopeful that we’ll be able to move this rig in three or four days from location to location,” Sheffield said. “… We feel fairly confident that we can drill four wells in a season and once we get our legs and our operations under way we’re hopeful that we’ll be able to drill five wells per season.
“We need to get the rig up here and shake it out and get some experience under our belt and prove what we can do.”
But, although this purpose-built exploration rig can’t drill the deep development wells or long horizontal wells of the more conventional North Slope rigs, Sheffield thinks that the cost reductions that rig will achieve will more than compensate for any limitations.
“There aren’t any easy wins out there from a cost reduction standpoint so you have to find a number of different ways to save money to make it add up to a significant issue,” he said.
