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Quantifying the prize: what’s out there at 4 miles? 7 miles? beyond?
BP gets back into extended reach drilling in Alaska, where wells have gone out 20,000 feet; company’s goal is to identify reserves if ultra ERD wells could be drilled out 30,000, 40,000 feet or farther Kristen Nelson PNA Editor-in-Chief
Wells on Alaska’s North Slope have reached out as much as 20,000 feet from the surface drill site to targets — a lateral distance of almost 4 miles. Wells at Wytch Farm in Great Britain have reached out more than 35,000 feet, a departure of almost 7 miles.
If Alaska wells could reach that far — or farther — what reserves could be recovered?
BP Exploration (Alaska) Inc. is looking at that question now.
The company stopped drilling extended reach wells — those which reach out a long distance from the pad — after oil prices crashed in the late 1990s, because extended reach drilling, ERD, is expensive.
But about a year ago, BP’s Alaska Drilling and Wells Engineering and Assurance Manager Chuck Mallary told PNA, the company started thinking again about what might be possible with ERD.
The Alaska ERD wells, reaching out some 20,000 feet, are where the company has been. It’s trying to determine now where it could go. Pushing the envelope BP has world-class experts working on ERD conceptual engineering in Alaska, Mallary said, experts in areas like well bore stability, drilling mechanics and modeling — some in Alaska permanently and some on loan from BP’s Upstream Technology Group.
The goal is to identify “the things that you could do with the reserve base in Alaska if you had the capability to drill outside this envelope” of the 20,000 foot departure wells reached in Alaska — and perhaps beyond the 35,000 foot plus departure wells at Wytch Farm.
One big issue being considered in the conceptual engineering, Mallary said, is the existing North Slope rig fleet. There are large rigs on the North Slope, but BP believes some of the wells under consideration “are getting close to the limit of what our North Slope fleet could do.”
“By finessing, by careful planning and thoughtful execution, we can probably extend our departures further with the existing fleet. But if we’re really serious about pushing out even further, we may need to upgrade the rigs. Depending on the scope of the wells, we may need to get new-built rigs to do that.” Getting back into the game A pair of high-departure sidetracks is currently under way with Doyon Drilling Inc.’s rig 14, Mallary said. Wells have been drilled in Alaska with longer departures than these two wells, “but they’re still challenging wells and I think that you could make an argument that we’re already getting back in the game.” In addition to honing its skills on wells like those, BP will also be rebuilding a team to drill ERD wells. A lot of the engineers, service industry people and drilling rig people have moved on since the 1996-98 wells were drilled, Mallary said, “and the amount of teamwork and focus on the task at hand is so important in delivering the final result.”
Detailed engineering is under way for four wells at Milne Point later this year “that are very close to what we’ve done before, if not a little bit farther.” The Milne Point wells will provide an opportunity for BP to try technology that has come along in just the two or three years since BP last drilled ERD wells in Alaska, Mallary said. New technology A specialty drilling tool, rotary steerable systems, is one new technology BP has been working with, Mallary said. Drilling curved well segments is essential to any directional well, ERD or not, he said. With conventional steerable mud motors, a technology that has been used for 15 to 20 years, drillers stop rotating the drill string when they need to drill a curved segment. The mud motor has a bend in it, and as mud continues to be pumped through the mud motor, which is turning the bit, you drill a curve.
But in ERD wells, this “slide drilling” can be both difficult and costly because of the friction in the well bore. Penetration rates are much lower while “slide drilling,” and hole cleaning is much less efficient than when the drill string is rotated.
The new rotary steerable is an “intelligent” bottom hole assembly designed by directional drilling companies to drill curved segments while the drill string is being rotated. This technology has come out of prototype and into commercial systems in the last two or three years. “In Alaska, our first test of rotary steerables was in ‘98 and then it got slow and we didn’t need it,” Mallary said, “but this year we’ve had very successful runs with two different versions of rotary steerable systems.” No drilling surprises You also have to know what your target looks like.
Mallary said “in BP we’re calling it no drilling surprises.”
When you’re going to spend a month or two just drilling out to the reservoir, he said, you want to make sure you don’t have any “train wrecks” on the way there and you want to be dead certain you’re drilling to the right place.
The company is using a high-technology planning room, the “HIVE”, short for highly interactive visualization environment, for multi-disciplinary subsurface planning. The technology integrates seismic and geologic mapping and puts it “into an environment where all the disciplines that are involved in planning and drilling the well can develop a common understanding.”
The goal with this tool, Mallary said, is to make sure the entire team — drilling engineer, geophysicist, reservoir engineer, production engineer — see and understand the reservoir and the overburden in the same way. It is having an added benefit, he said: “we’re finding out that it really improves our planning cycle time. … If you can get everybody in the room working on the same problem you can get it done faster.” Completions also an issue Another technology BP is looking at for ERD wells is something called “intelligent completions.” The idea, Mallary said, is that once you complete a well it should require minimum workovers — especially important in ERD wells because of the cost of going back in and working on an extremely long well bore. Instead of having to go back “into these big ERD wells with slick line tools or wire line … we could do things like that with fiber optics or by sending pressure pulses or electrical signals between surface and the completion,” Mallary said.
The goal, is said, is to complete wells for the life of the well, to minimize the number of times that you have to turn the well off and go in and diagnose or fix something because it’s broken or because reservoir conditions have changed.
While a lot of the technology that could be used in an “intelligent completion” is still in research and development, he said a lot is already on the market. Ultra ERD is outside the envelope If regular ERD is inside the envelope of what’s been achieved in extended reach drilling, then ultra ERD is outside the envelope, “and it’s thinking really big,” Mallary said.
“Here in Alaska we can progressively step out a long way before we get outside the worldwide envelope.” But, he asked, what if you could drill 40,000 or 50,000 feet (7.6 to 9.5 miles)?
“Just think what you could do if you had reliable, cost-effective technology to do that sort of thing.”
One thing either ERD or ultra ERD could do is to leverage existing infrastructure — longer wells could reach reserves from existing pads, use existing pipelines and existing facilities.
“Using ERD to put new production into existing facilities helps to extend the life of mature fields already on decline,” Mallary said. Conceptual study close to a wrap The conceptual study team looking into ERD and ultra ERD “is very close to concluding that phase of work” and presenting results to management, Mallary said, including: quantity of reserves that could be reached at different distances; identification of what is technically feasible from a drilling and completions standpoint; the risks and uncertainties involved.
Right now, he said, “there’s tremendous interest in BP for reestablishing extended reach drilling in Alaska.” And it’s not just about Alaska resource development — the company sees strategic value as well, he said.
“The Wytch Farm ERD campaign is completed,” Mallary said. That project “developed a lot of technology, a lot of understanding and a lot of learning that we were able to transfer around the world and incorporate in other projects.
“If BP can pass the ERD baton from Wytch Farm to Alaska,” Mallary said, “there’s no telling how far the next well might go.”
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