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Work under way Alpine facilities expansion in progress; field will be down for four weeks in July Kristen Nelson Petroleum News Editor-in-Chief
Onsite work began in March for facilities expansion at the Alpine field on the west side of Alaska’s North Slope. The work, approved in two phases, will increase produced water handling and allow Alpine to produce 140,000 barrels per day of oil, up from its current capacity of 100,000-105,000 bpd.
There are two separate projects at the Colville River unit, Alpine capacity expansion phase 1 or “ACX1” and Alpine capacity expansion phase 2, “ACX2.”
Alpine field operator ConocoPhillips has to do a shutdown for each phase of the work, one this summer and one next summer.
Once ACX2 was approved earlier this year, John Whitehead, ConocoPhillips Alaska’s vice president for the western North Slope, told Petroleum News June 17, “we identified … the ability to actually complete a lot of the modules and be able to do the tie-in work in ’04, to minimize the shutdown that we’re going to have to do in ’05.”
Whitehead said the shutdown this summer is planned to begin in mid-July and to last four weeks. Tweaking has already been done ConocoPhillips Alaska (78 percent) and Anadarko Petroleum (22 percent) are partners in the Alpine field, which ConocoPhillips operates. When development was announced, production was planned for 70,000 barrels per day.
But further study of the reservoir and the decision to go with horizontal wells, waterflood and enhanced oil recovery changed that initial capacity to 80,000 bpd, Whitehead said.
After the field came on production in November 2000, “they ramped up to the 80,000 barrels a day and then as … they drilled more wells they recognized that they had well capacity to go above the 80,000 barrels a day.”
The tweaking that was done then was “a real team effort” between operations, engineering and drilling, he said, “to take advantage of that opportunity.”
Sometimes production bottlenecks involved learning how to operate at a little higher rate, sometimes it was something like replacing a valve with a little bigger valve — and for the reservoir engineers, it was a matter of working on “how do we manage this reservoir correctly at a higher rate,” he said.
This work began in 2001, Whitehead said, and over about a year’s time the de-bottlenecking kicked up the Alpine production rate to 100,000 to 105,000 bpd.
In addition to de-bottlenecking, ConocoPhillips did an Alpine capacity expansion “junior” project on the reservoir management side. ACX Jr., completed in the summer of 2002, upgraded transfer pumps at Kuparuk, where Alpine buys its seawater for injection.
“And that upgrade allowed us to ship about 10,000 barrels a day more water to Alpine so that we could use that to basically replace the oil that we were taking out of the ground,” Whitehead said. ACX1 primarily directed at produced water ACX1, approved last year, will increase oil throughput at Alpine by about 5,000 bpd with “some of those final tweaks to the plant for that higher rate …,” Whitehead said, “but the real thing that we did with ACX1 was to increase our produced water handling capacity.”
The plant was designed to process 10,000 bpd of produced water — water mixed in with the crude oil when it comes out of the ground — which needs to be separated and re-injected. Since 95,000 bpd of seawater are also being injected, “at some point you start producing that water back and you want to re-inject” it, Whitehead said. So ACX1 increases produced water handling capacity to 100,000 bpd.
ConocoPhillips knew that produced water handling capacity would have to be increased over the life of the field, he said, but that expansion was moved forward “because we were producing our oil with our accelerated rate, it just drove us to have to do it a little sooner.”
The engineering is complete for ACX1, Whitehead said, and the modules were fabricated in Anchorage and trucked out to Alpine over the ice road last winter. Implementation overlaps ACX1 and ACX2, each about $60 million, were approved separately, and implementation was going to be done separately, with a shutdown planned this summer for ACX1, followed by “a fairly long shutdown” next summer for ACX2. But after ACX2 was approved early this year, Whitehead said, planners identified that a lot of the modules for both ACX1 and ACX2 could be completed and the tie-in work done this summer, shortening the shutdown that will be required next summer.
The projects remain separate, he said, “except when it comes to doing the construction piece.”
ASRC Energy Services and VECO are the prime contractors, and Whitehead said they “did a really fantastic job for us as far as identifying opportunities and just working closely with us to take advantage of that opportunity that we identified.” ACX2 will be completed in ’05 It wasn’t possible to complete ACX2 this summer because some equipment couldn’t be moved ahead fast enough to get it to the slope for ice road delivery this year, so parts of ACX2 will come up on the ice road this winter and be installed next summer.
But accelerating modules and piping for ACX2 make next summer’s shutdown shorter than it would have been, Whitehead said.
ACX2 is designed to increase oil capacity to 140,000 barrels a day, although Whitehead said that with normal operational ups and downs Alpine probably won’t see an annual average of 140,000 bpd. Seawater injection will be increased to a little more than 130,000 bpd to compensate for increased oil production.
And ACX2 includes a small increase in gas handling capacity: “Right now we can produce about 160 million (cubic feet) a day and we’ll go to about 180 million,” Whitehead said. That gas is re-injected, he said, both as miscible injectant for enhanced oil recovery and as pressure support in the reservoir.
Full rates from the ACX2 work are expected in the third quarter of ’05. Maintenance also during shutdown ConocoPhillips is also taking advantage of the shutdown to do maintenance that can only be done when equipment is down. Alpine is a one-train facility, Whitehead said, which means there is one primary generator, one primary compressor. There is a short maintenance shutdown once a year for inspection of critical equipment, and once every four or five years there is a longer shutdown so that the machinery can be inspected in more detail and planned parts change out done.
“We’ll be doing all that operational work during this shutdown, too, so that’s adding more people, more complication to the shutdown and just more coordination,” he said.
The maintenance people have to coordinate with the construction people to make sure they stay out of each others way, and also to share equipment.
And because wells will be shut in during the shutdown, that gives engineers an opportunity to check bottomhole pressures, “so from a reservoir standpoint it helps them get a better understanding and helps them better manage the reservoir.” Pre-shutdown work under way Planning for the shutdown began in January, Whitehead said, and included outside experts in shutdown planning, as well as a peer review within ConocoPhillips.
The main ACX work requiring a shutdown is work inside the vessels.
“We have to shut the vessels down, de-inventory them, safe them out” before people can go in to do the necessary work to increase throughput capacity.
Then there is the new piping, which again requires that we “depressure and de-inventory lines, safe them out, before we can make tie-ins.”
There will be backup power generation while the main generator is down, and seawater injection will be started back up before the plant comes back up, Whitehead said, even though no oil will be produced during shutdown. Prior to shutdown work under way now Eight million pounds of modules, equipment and piping for both projects were moved to Alpine on the ice road which was completed in January, Whitehead said, and the ramp up for the work began in early March.
Part of the planning process was to identify work that could be done prior to the shutdown, including setting modules on pilings and putting piping in place in pipe racks, ready to be tied in during the shutdown. Work started with about 50 people at Alpine in March. “We have about 250 right now on construction and another 50 doing kind of that additional O&M work, and then our normal 100-plus people up there.”
Because there is no road to Alpine, scheduling workers around the number of people the camp can hold — about 500 — has been part of the challenge for shutdown planning, he said.
And development drilling at Alpine, expected to be completed at the end of this year or early next year, was also part of the planning, Whitehead said.
Because there isn’t a lot of room on the main pad, Colville Delta 1, the drilling rig — which drilled two wells at the main pad this spring — had to be moved over to the second drill site, Colville Delta 2, to make room.
Whitehead said that once this summer’s work is done, over about a week’s time Alpine production will get back to where it was, and “then on top of that I think we’ll pretty quickly get up to the 5,000 incremental barrels that we get with ACX1.”
The final ramp up, to 140,000 bpd, won’t take place until next year, when ACX2 construction is complete.
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