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A portable exploration solution Anadarko Petroleum plans to test its Arctic platform this winter, will allow winter exploration drilling without ice roads and ice pads Kristen Nelson PNA Editor-in-Chief
The window for North Slope winter exploration is shrinking — and costs are expanding. Anadarko Petroleum Corp. has a plan to deal with both.
It will test a portable drilling platform this winter which would allow companies to save money by exploring without ice roads or ice pads, and over a longer period of time each year. And the platform could also replace gravel pads for production facilities.
The Arctic platform adds time to the drilling season by eliminating ice roads and ice pads, the company’s Alaska public affairs manager, Mark Hanley, told PNA Oct. 22. That becomes more important, he said, as you get farther from infrastructure, “if you want to go a long ways away, it takes you the whole winter just to build your ice road.”
Requirements for ice: water, flat surface Gravel used to be used for exploration, Bill Fowler, Anadarko’s Houston-based environmental supervisor, said in the same interview. Gravel became environmentally unacceptable, so companies moved away from it the same time exploration was moving away from the foothills to the coast where the land was flat and there was water: both conducive to ice pads and roads.
But Anadarko is looking in the foothills again, Fowler said, and there are fewer lakes as you move towards the mountains, so there’s less water. And there are terrain issues — the water won’t stay in place long enough to freeze. Anadarko has determined, he said, that a 6 percent grade is the limit for using ice.
And there’s the distance: you build about one mile of ice road per day, so with a 120-day season and prospects farther out, perhaps 50 or 60 or 80 miles, you don’t have time to drill after you’ve built your ice road.
Fowler said Anadarko took the problem to Keith Millheim, Ph.D., the company’s Houston-based manager of operations technology.
A scaled-down version of the solution will be tested this winter on a 3,000-3,500 foot gas hydrate core well, Fowler said, “fairly close to infrastructure and at a lower cost than a full-scale test.”
Rolligon moveable modules The concept is simple, Millheim said: “you’re putting an offshore platform into the context of onshore.”
Anadarko has brought the concept onshore and “modularized it so it’s easy to move the equipment out there” by helicopter or rolligon, Fowler said.
When the modules are assembled, the platform is a self-contained elevated drilling unit on legs sitting 12 feet above the tundra.
“The legs are made of steel, special steel for Arctic conditions,” Millheim said, and are helical in shape to provide more support for the platform. “The modules themselves are made of aluminum,” which is light weight and handles variations in temperature very well.
The first installation step is done with a common auger, Millheim said: Holes are drilled about 20 feet deep along a grid. The legs, which have coils to circulate either hot or cold fluid, are placed in the holes.
The modules, interlocking pieces 12.5 feet wide by 50 feet long, come out by rolligon, Millheim said. The deck pieces are aluminum with reinforcing materials on the inside and sit on top of a base of shallow containers which capture any deck fluids or other spillage.
The first sections are installed by a crane on a rolligon; when a large enough working surface is in place, the crane moves to the platform to install the rest of the modules.
“Everything is basically done in modules so they can be hauled off and plugged together,” Millheim said.
“And I’m very optimistic about it. If it works, this would be the new exploration type system that we could use in frontier areas,” he said.
Year-round work The concept with these Arctic platforms is to be able to supply them — even move them — in the off season, Hanley said. He said the company understands there would be restrictions, but if you have two, or two and a half platforms, you can set up in your first prospect area and begin setting up in the second, and some components will already be there on the second platform.
Millheim said that the piping and wiring, things that take time to put together, could be duplicated and you would just move the power package, the main pumps and the draw works. “So you might have what we’d call one and a half rig to be servicing in a kind of hopscotch.”
Rolligons are approved now for year-round tundra use, Fowler said, although there is a closed period between breakup and July 15. The existing fleet, he said, puts 4 psi to 5 psi of footprint weight on the tundra, but new technologies get that down to 1 psi.
Beyond exploration The Arctic platform can be expanded for production work.
Fowler said agencies which have seen the concept are excited about its potential for production. Most of the industry’s impact comes at development, he said.
“And if you sum it up, the majority of the impacts that the agencies see and are concerned about are gravel — gravel pads and gravel roads — being placed on the tundra,” Fowler said. The long-term impacts are difficult to mitigate.
What remains when an Arctic platform is moved, Millheim said, is 20-inch diameter holes, down to 15 to 20 feet. You fill the holes and you plant the 20-inch diameter surface.
North Slope production facilities sit on pilings now, Fowler said. The platform would do away with the gravel pads. The modules would be smaller and more assembly done on site.
This winter’s modules under construction This year’s Arctic platform is about half done, Millheim said, and will be trucked up in December. It will use a small Dynatec-NANA mining-type drilling rig capable of drilling up to about 6,000 feet, he said.
This scaled down version of the platform, including the rig, will weigh less than half a million pounds, Millheim said, compared to one to two million pounds just for the big rigs alone.
It reduces the number of trips, the impacts and the cost, Hanley said.
Millheim said it wasn’t possible to compare this prototype to the cost of a standard winter exploration setup because it is a prototype.
“Obviously,” he said, “we’re designing this to significantly cut costs. And improve what we call the cycle type of exploration.”
This eliminates the cost of ice, Fowler said. And unlike ice, “this is reusable” so the cost is amortized over time.
Hanley said Anadarko wouldn’t be spending the money if it didn’t think it could reduce the cost, “but in the end it does have to be economic.
“If it isn’t — if it doesn’t reduce costs enough, you’re still not going to see development.”
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