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Drilling in the fast lane
Alpine drilling passes million-foot drilling mark on 69th well Kristen Nelson Petroleum News Editor-in-Chief
In four years of continuous drilling, ConocoPhillips Alaska and partner Anadarko Petroleum have drilled more than a million feet of well bore at their Alpine field on the western North Slope of Alaska.
That million-foot mark was passed in April on the field's 69th well, Chip Alvord, Alpine drilling team leader, told Petroleum News May 28, almost 50 miles a year of drilling since Doyon Drilling's rig 19 moved out to Alpine in February of 1999.
“Doyon's done a super job managing the rig and the people and everything out there,” Alvord said. “They've really done a great job of keeping the rig up and running and managing the people … keeping the best people they can.”
The last couple of winters Doyon rig 19 has left Alpine on ice roads for exploration drilling, and that may happen again this winter, but the rig's always come back, he said.
One of the reasons for the drilling success at Alpine is that ConocoPhillips and Anadarko “agreed to a plan of development ahead of time for all 94 wells, so getting them approved and processed through the approval process has been a lot easier,” Alvord said.
Mark Ireland, ConocoPhillips' development manager for the western North Slope, said funding for all of the drilling “was all part of the original AFE (authority for expenditure), so the dollars were already approved and then it was just a question of agreeing on final bottomhole locations” and those are reviewed “as we get more information from previous wells.”
Teamwork in a showcase development Ireland characterized the drilling success at Alpine as the result of “just excellent teamwork, with people on site, regardless of what company they work for, people in town… It's been an important project for us and I think everybody… recognizes the importance for us and for the industry and the state… and are really going that extra mile to make sure everything is successful. And that's definitely paid off.”
“It's all pride in the operation,” he said. “Because it is kind of a flagship for future developments,” so the project gets a lot of visitors coming through “and there's a lot of pride in being able to work there.”
“It's basically the showcase field for new developments on the North Slope,” Ireland said. Horizontal section substantial All of Alpine's wells, producers and injectors, are horizontal, with the well angled to pass horizontally through the producing reservoir. Horizontal footages within the reservoir range from 3,000 feet to 6,000 feet, with one 6,000 foot horizontal section and three wells with horizontal sections more than 5,000 feet in length, Alvord said.
Of the 1 million feet drilled, 232,000 feet have been horizontal section in the reservoir, Ireland said, “so that gives us over 23 percent of the feet drilled are productive in the reservoir section.”
Compare that, he said, to vertical wells — those probably would have had less than 1 percent of footage drilled in the reservoir section. Benefits of continuous drilling Drilling performance has continued to improve, Alvord said. “At Alpine we started out doing the wells in about 16 days — over time we've worked that down to an average of 12 days.
“Pretty good considering that we drill three different hole sections per well, these are all horizontal wells and we're not drilling the deeper, more challenging wells.”
The wells for 2003, Alvord said, have been averaging 17,000 to 18,000 feet.
And since startup the drilling trend — measured in days to drill 10,000 feet — has been decreasing, he said. “Even after 70 wells we're still continuing to optimize.”
One reason the drilling is going so well is that Alpine is continuous drilling at a new development.
“Typically you drill a few wells at a pad and then you go somewhere else. We've got the benefit of four years of continuous work,” he said. And because Alpine is a continuous drilling program “you're not shutting down and then starting up with new people.” There has been a change in the drilling crews, “but we've been able to keep the core people — tool pushers and drillers,” Alvord said.
“Doyon's done a great job of managing the rig and the people. MI Drilling Fluids manages all the fluids out there … and about the last year we've been using an oil mud that's really doubled or tripled our production,” Alvord said. Another plus is that MI has a mud plant at Alpine to process muds “and that's really helped optimize a lot of our fast drilling productivity,” he said. Drilling mud change The drilling work has gone smoothly, Alvord and Ireland said.
With one exception. The new drilling mud is the solution to that problem.
“Alpine wells have outperformed our expectations,” Ireland said, but that changed when the rig moved to the second drill pad, CD2. “The first few producing wells at CD2 didn't out perform our expectations,” Ireland said. “They were a bit below our expectations.” At that point they switched to a mineral oil based mud system.
“And we've seen that product basically increase well rates there by two to three times over what the other wells were producing at CD2.”
Alpine is the only field on the North Slope using mineral oil based drilling mud. Unlike diesel-oil based mud systems, the mineral oil is biodegradable, Ireland said.
“More expensive, but from an HSE (health, safety and environment) perspective it really is the way to go,” Alvord said.
Doyon and MI and ConocoPhillips had to train using the new mud, but first they had to get it to the field.
Logistics at Alpine Since Alpine is a roadless development, all the drilling consumables have to be moved out on ice roads during about a two-month window. It's some 450 truckloads of things like casing, muds and cement, Alvord said, about 20 wells worth of supplies per winter.
Most of those supplies go to Fairbanks by rail and are trucked to the slope “and then they'll stockpile all the flatbeds waiting for the ice road to get in and then it's like the Oklahoma land rush when the ice roads get built.”
It wasn't winter when they switched to the mineral-oil based drilling mud, Ireland said, so MI had to work out the logistics of getting the mud to the field. They couldn't truck it out.
And, said Alvord, there isn't enough storage for all the fluid needed for a whole year.
“We had to pump that fluid through our diesel supply line that connects us back to Kuparuk,” Ireland said.
The mud comes out of Louisiana and is barged, railed and trucked to Kuparuk, and then pumped through the two-inch diesel line about 3,000 barrels at a time, “usually enough to do three wells,” Alvord said.
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