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Arctic platform in place Anadarko drilling hydrate well from raised, modular system Kristen Nelson Petroleum News Editor-in-Chief
Anadarko Petroleum Corp. began drilling and coring a gas hydrate well south of Kuparuk April 1. It is the first time anyone has purposefully drilled a hydrate well on the North Slope.
What the company is drilling from is also a first.
Anadarko is testing a prototype Arctic platform which sits on legs above the tundra; a drilling platform built of modular sections and legs designed to be assembled and disassembled in different configurations as needed.
Mark Hanley, Anadarko’s public affairs manager for Alaska, told Petroleum News in an October interview that as exploratory drilling moves “farther and farther from infrastructure” into the National Petroleum Reserve-Alaska and into the Foothills, “we want to do something that decreases the impact on the environment and potentially allows us to extend the drilling season, which is critical, because it’s getting shorter and shorter.”
Bill Fowler, Anadarko’s Houston-based environmental supervisor, said “the dependency on using ice for exploration has really limited exploration on the North Slope,” where — in addition to ice roads to reach objectives — companies use ice drilling pads. As Anadarko looked at exploring in the Foothills, Fowler said, two things became obvious: because there are fewer lakes, there is less water available to build ice roads and ice pads; and because the terrain is no longer flat, as it is farther north, the grade makes it difficult to build with ice.
On relatively flat terrain, “ Fowler said, “the water stays in place long enough to freeze, but when you add some grade to it, it wants to run off so it’s hard to build an ice road or an ice pad and keep it where you want it.”
And, Hanley said, it’s hard to pull heavy equipment up grade on an ice road: “you’ve got traction issues just like you would on any other hill.”
A 6 percent grade, Fowler said, is about the limit for using ice, which is six feet of rise in 100 feet. “It’s not much,” he said. A mile a day Distance is also important, Fowler said, with one mile a day of ice road about what you can expect to build: 30 days for a 30-mile ice road. That makes ice roads a good solution within 20 to 30 miles of infrastructure, he said. But at 50 or 60 or 80 miles from infrastructure, when you have to build that much ice road, “if you take 80 days to build an ice road, and you’ve got a 120-day season, you don’t have time to drill your well,” which is typically a 30-45 day job.
In the Foothills, where targets would be deeper, it would take even longer to drill a well, Fowler said.
Anadarko looked at the challenges and went to Keith Millheim, the company’s Houston-based manager of operations technology, for answers.
Those answers are being tested this winter.
Fowler said the gas hydrate project, “Hot Ice,” a research project for which Anadarko has some Department of Energy funding, is a good one to test the Arctic platform because it’s a shallower well, some 3,000 to 3,500 feet, about half the depth of conventional exploration, and the well will be cored.
“So we can use a smaller rig and then we can test a scaled down version of this Arctic drilling platform concept,” Fowler said. It gives the company an opportunity to test the concept, learn from the prototype and determine whether it’s the optimal design or not.
“It allows us to test the concept fairly close to infrastructure and at a lower cost than a full-scale test,” Fowler said.
Prototype in place Millheim said that if you look at old offshore jack-up rigs used in the Gulf of Mexico you can get a feel for the dimensions of the Arctic platform, which could be as large as 32 modules (each 50 feet by 12.5 feet).
And, Fowler said, that’s also the concept: “It’s an old idea with a new application. The compact design of drilling platforms has been around for years,” he said, and Anadarko has lots of experience with them in the Gulf of Mexico.
The prototype in place on the North Slope used 21 modules and 50 legs, Hanley told Petroleum News April 2. There is a drilling platform with 16 buckets — the base of the platform, which catches any runoff, hence the name — which measures 100 feet by 100 feet, he said. The drilling platform has buckets 50 feet by 12.5 feet.
Connected to it by a gangway is the camp, with custom-built camp modules. Modules for the camp platform are larger, 60 feet by 12.5 feet.
The legs and buckets were built in Houston, trucked to Seattle, shipped to Anchorage and trucked to Deadhorse and on to a staging pad on one of the gravel roads. From there, Hanley said, they went out to the site by rolligon.
The platform pieces left Houston around the first of January and by the end of January all of the buckets and legs had reached the drilling site. Hanley said there was some prep work required at the site and then it took the month of February to get the holes drilled, the pilings or legs put up and the modules put in place.
There were some days when they couldn’t work because of the weather, Hanley said.
Assembly would be quicker in the future: “It’s a prototype,” he said, “even aside from weather days, we’ll be able to shorten it next time.”
Most of March was spent getting the rig on top of the platform, the camp and testing modules in place.
Anadarko is using a mining coring rig because the hydrate well won’t be as deep and will be continuously cored. The company anticipates that it would use the “big brother” of this rig for traditional drilling and that the platform would be larger, Hanley said. The prototype was sized for the smaller rig. Small ice pad Augers were used to drill holes for the legs and cranes and forklifts were also required, Hanley said. Anadarko tested different cranes in assembling the prototype, and put down a small ice pad to be able to work off the ground to test different types of equipment.
The gas hydrate test well was spud April 1, Hanley said, and drilling will take two to three weeks.
Once drilling is complete, he said, the platform will be safely suspended and Anadarko will go back later and complete the well and test it.
The platform will stay in Alaska, but Hanley said the company doesn’t know whether they will be ready next winter to move it to a new prospect or whether it will be stacked.
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