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Marathon developing technology
for onshore Cook Inlet Mobile rig, new completion system designed for company’s work on the Kenai Kristen Nelson PNA Editor-in-Chief
Marathon Oil Co., the most active Cook Inlet gas explorer in recent years, is using new technology on the Kenai Peninsula — technology developed specifically to reduce development costs in the gas fields the company operates.
John Barnes, Marathon’s Alaska region manager, told the Alaska Support industry Alliance March 9 that Marathon began drilling last year with its own rig, Glacier Drilling No. 1, a truck-mounted rig operated for Marathon by Inlet Drilling. There is a separate substructure, built specifically for the rig, Barnes said, which is also mobile, as are two pit and pump trailers, including a totally self-contained mud system.
“The first well was spudded April 7 of last year,” Barnes said. “Since that time the rig has drilled to nearly 12,000 feet (total depth); it’s also drilled a 2,600 foot horizontal at nearly 9,000 feet. …
“It’s basically met or beat every drilling curve that we’ve compared it to in the Cook Inlet and we’re looking at the bigger drilling rigs that have been used historically,” he said.
The rig drilled more than 50,000 feet of hole last year.
Barnes showed a photo of the rig drilling in the Cannery Loop field, and said that the field is in a neighborhood, right near the Kenai River. The rig was designed for such work, he said, with a small footprint, total containment of fluids and hospital-quiet mufflers.
“As far as I’m aware, this is probably one of the few times in North America that a drilling rig is owned by an operator. And I can tell you,” Barnes said, “it’s a very interesting time to try to explain to your management why you should be different than everybody else.”
So why did Marathon buy its own rig? Barnes said the company anticipated a multi-year drilling program, knew there would be a need for the rig in the Cook Inlet area and wanted to be sure a rig would be available when Marathon needed it. The company also wanted a rig that was the right size for its projects, and it wanted to lower its costs.
“If you can lower your cost on your wells that you drill for a fixed capital budget, you can drill more wells,” Barnes said.
Reduced environmental impact was also important. “If you’re going to go ahead and construct a drilling rig, there are things you can do to minimize the impact,” he said. “Finally, why are we doing it? We’re just trying to be a good neighbor. When we’re operating here, in a neighborhood essentially, or out on the wildlife refuge, we try to set the standard of how we need to operate,” Barnes said. Marathon operates the Beaver Creek, Cannery Loop, Kenai and Sterling gas fields on the Kenai Peninsula. Completion customized for Kenai gas field “After the well’s drilled, you want to complete it efficiently,” Barnes said.
So in addition to its new drilling rig, Marathon is using a completion technique on Beluga formation wells in the Kenai gas field that was invented for that formation. The Kenai gas field wells are drilled through multiple pay intervals, he said, and you can have different qualities of rock in the same well — sometimes high quality, prolific zones and sometimes lower zones that need to be stimulated to produce.
“You either pump some acid to clean them up or perhaps you pump a fracture treatment,” he said, and Marathon’s approach was to stimulate each interval separately because stimulating multiple intervals at once doesn’t do as good a job as if each interval receives a specific treatment designed for it.
But individual stimulations might require a week’s work because of multiple wireline trips and multiple fracture treatments.
“So the goal here was obviously cost control,” Barnes said.
The new completion system is a continuous completion technique. Perforating guns are run on the outside of the casing, and cemented in place. The lowest interval is perforated, then treated. When the shots are fired for perforation of the next interval, an isolation valve closes, separating it from the lower, previously treated interval. When all of the intervals in the well have been treated, the isolation disks are broken out.
The system — although invented for the Kenai gas field Beluga formation — was run first in the Lower 48 and then in February was run in the Kenai gas field for the first time, with 15 gun modules, setting a world record, Barnes said. A second well was scheduled to be completed using the system March 10, again with 14 or 15 gun modules.
“Oftentimes you’ll hear about inventions that have been conceived on a bar napkin and I’ve seen one actually happen now in my career,” Barnes said. “I didn’t see the napkin, but I … approved the business expense report for the bar.”
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