By Patty Sullivan, Photography by Judy Patrick Photography
In July, ConocoPhillips Alaska broke the state record for longest rotary well — 32,468 feet. Doyon Rig 25 drilled to a measured depth of 14,370 feet before turning horizontally into the reservoir and drilling another 18,098 feet, completing six miles of drilling.
“When we drilled the first horizontal well in Prudhoe Bay roughly 30 years ago, it almost felt like Christopher Columbus sailing off the edge of the earth,” said Drilling Manager Chip Alvord. “We just keep pushing the envelope. I didn’t think we’d ever be drilling wells like this.”
At CD5-98, ConocoPhillips not only broke the Alaska record but also an onshore North America record, for total combined footage of 47,828 feet for a single well and two laterals.
Wells this long have led to ConocoPhillips Alaska setting the record for 17 of the 20 longest wells in Alaska since 2010. The top 10 longest wells in Alaska were drilled at CD5, which achieved first production in 2015.
Reaching more without expanding the pad
CD5, located west of the Colville River Delta, extends the Alpine reservoir into the National Petroleum Reserve-Alaska. To tap additional resources without expanding the footprint, the team pursued extended length laterals and used multilateral drilling technology.
“It’s a bounty at CD5; we have a lot more oil than we thought when going in,” Alvord said.
CD5 was estimated to produce 16,000 barrels of oil per day (BOPD) gross and it is currently producing about 37,000 BOPD gross average year-to-date through November.
“Collaboration and innovation among the Subsurface, Drilling and Wells teams is critical to maximize recovery,” said Steve Thatcher, manager, Western North Slope (WNS) Development.
“CD5 started as a 15-well development from a 12-acre gravel drill site. To drill these targets without expanding our footprint, the teams devised multilateral concepts and pushed the limits of the rig to exploit available well slots. We’ve now completed two pipe rack expansions to maximize the full 12-acre space, which our Capital Projects team successfully executed.”
“Four to five years ago no one thought that we would be able to deliver these kinds of wells with the rig we have,” said Johnson Njoku, supervising drilling engineer for the Western North Slope. “The equipment hasn’t really changed. It’s about folks willing to do the engineering work, pushing the envelope, and the team in the field delivering. This would not have been possible without leadership support.”
Alvord agreed. “Johnson and his team, working with the asset team, have been very aggressive in doing all that is required to drill these long laterals,” he added.
Risk accompanies records. It’s possible for pipe to get stuck in long wells, which affects the economics of the project. Fortunately, it’s rare.
Putting liner in long wells also has challenges. With record wells comes record placement of liners.
Njoku said that on Well 98 the liner length is about 3.5 miles. “To push it all the way down the well more than six miles required engineering modelling, custom drilling fluids to reduce wellbore friction, and a specially designed bottom hole assembly,” he said.
“Imagine this hole that’s 6.5 inches in diameter and 3.5 miles long, and you’re trying to stuff a 4.5-inch piece of pipe into it. There’s a lot of buckling involved, and often you have to rotate the pipe to help it get in the ground,” Alvord said.
Nick Pysz, supervisor, Western North Slope Subsurface, gives us a glimpse underground. “Keeping the drill bit in the right place is crucial to delivering the well. We often have rock above and below our target sands. Our geologists and geophysicists are skillfully working with the rig around the clock to geo-steer the drill bit in undulating 10-foot-thick sands, from some 25,000 feet away. Straying out of this productive sand can be the difference between completing the well on time and budget or having to perform a costly sidetrack,” Pysz said.
Optimizing development is the job of the asset team. “It’s finessing the constraints of 80 subsurface well targets into 43 surface locations, so you have to do something different,” Alvord said. “When we have these long laterals, the intervention is a lot more challenging. If you have a 7,000-foot lateral, you can probably get all the way to bottom with production logging tools, but in 3.5 miles that’s not going to happen. So, kudos to the asset team for balancing the risk and being innovative in their well design,” said Alvord.
“This group wants to give its best effort for the company,” Njoku said. “These records are possible because of the passion they bring to work every day.”
Records will take on a whole new scale when an innovative, extended reach drilling rig begins operating in April 2020 at Alpine. The largest mobile land rig in North America, Rig 26 can reach seven miles and will be able to capture previously stranded resources while located on existing drilling pads, eliminating the need to build more infrastructure.
No end yet to smashing rotary records in Alaska
While this article was going to print, the Alaska team achieved an as-yet unofficial new North American onshore record for longest well with a length of 33,768 feet, west of the Colville River at CD5 on Doyon Rig 25. Excellent geo-steering accompanied the new record. “The technique of steering the wellbore through the sand (oil) and staying out of the shale (no oil) is called geo-steering,” said Chip Alvord. “In this case they were able to stay 100% in the hydrocarbon pay zone the entire length of the lateral — 18,474 feet.”