Development at West Sak, the heavy oil accumulation at the Kuparuk field on Alaska’s North Slope, is in the news a lot these days (see story and maps in E&P section of this issue), but Kuparuk operator ConocoPhillips Alaska is also doing some innovative work to find oil targets at the field’s main reservoir.
The development team at Kuparuk is responsible for new developments such as West Sak, Matt Fox, ConocoPhillips Alaska greater Kuparuk area development manager, told Petroleum News in mid-December, but the team doesn’t “take our eye off the base production.”
Production from the main Kuparuk reservoir is some 150,000 barrels per day, Fox said, with the rest of the production coming from West Sak, Tarn, Meltwater and Tabasco. Alaska Department of Revenue figures show total production from the field for December averaged 198,179 bpd.
Production at Kuparuk, the second largest field on the slope after Prudhoe Bay, began in 1981. As of November, the most recent month for which data is available from the Alaska Oil and Gas Conservation Commission, 1.97 billion barrels had been produced from the main reservoir, more than 2 billion barrels from the Kuparuk River unit with Meltwater, Tabasco, Tarn and West Sak volumes added.
Main reservoir will soon go into decline
ConocoPhillips Alaska’s latest report to the Alaska Division of Oil and Gas on Kuparuk field development plans estimates that production from the main Kuparuk reservoir at the field will peak in 2006 at some 158,000 barrels per day, and then decline, averaging 137,000 bpd in 2007, 129,000 bpd in 2008 and 121,000 bpd in 2009.
The Department of Revenue’s fall forecast estimates that Kuparuk main reservoir production will drop in 2005 to some 144,000 bpd, while satellites will contribute 55,000 bpd, for an expected average of 199,000 bpd from the unit. In 2006, a total of 207,000 bpd is expected to include 141,000 bpd from Kuparuk and 66,000 bpd from satellites. By 2012, Revenue estimates that the main Kuparuk reservoir will be averaging 102,000 bpd, while the satellites will be producing some 100,000 bpd. The department’s list of Kuparuk satellites includes those presently under production: West Sak, Tabasco, Tarn and Meltwater.
3-D satellite this winter
ConocoPhillips is looking for additional drilling opportunities in the Kuparuk reservoir.
This winter, Fox said, “we’re running a new 3-D seismic survey across the Kuparuk” field.
Kuparuk, he said, “is one of the most complex fields in the world from a geological perspective, from a faulting perspective — it’s just incredibly complex. You combine that with the fact that we’re doing a miscible gas injection enhanced oil recovery. You can’t go many places in the world and find anything more challenging than this.”
Because Kuparuk is so complex, there are still opportunities there, Fox said.
The 3-D seismic that will be shot this winter uses “new technology that’s designed to allow us to image in the reservoir where the oil and gas are” allowing the company to target sidetracks.
Coiled tubing drilling
In addition to the new seismic, ConocoPhillips is also experimenting with coiled tubing drilling techniques.
Coiled tubing drilling has been used successfully at Prudhoe Bay, Fox said, “but the geology at Kuparuk makes coiled tubing drilling more of a challenge…”
In addition to 3-D and coiled tubing, ConocoPhillips is “building a new full-field reservoir simulation model at Kuparuk,” challenging “because of the complexity of the field.” The combination of new 3-D seismic, coiled tubing drilling and the new reservoir simulation model, “are going to allow us to get the most from Kuparuk, whether it’s through base management or through new development,” Fox said.
“We can’t stop Kuparuk declining,” he said, “but we can slow the decline down” and fill in with West Sak developments.
The combination of the new 3-D seismic and the reservoir simulation model and well performance will let ConocoPhillips identify areas where it doesn’t seem to be getting all the oil possible “if there were no geological problems.” The seismic will identify opportunities, he said, such as an oil trap “up against the fault, and then we can take a coiled tubing sidetrack up against that fault so that we pull the oil in.”
Horizontal wells
Coiled tubing wells will also increase rates, Fox said, because they are drilled as horizontal sidetracks. Coiled tubing can’t achieve the lateral lengths a rotary rig can, “but we don’t need those lengths because it’s quite a tight well spacing in Kuparuk anyway. What we need is the accuracy, the ability to see it and then get after it with the coiled tubing.”
Fox said ConocoPhillips plans to put the 3-D it shoots this winter to work before the end of this year and is doing some preparatory work so that the seismic can be very efficiently processed.
Once the seismic has been interpreted, he said, it will be used to identify targets for infill drilling at Kuparuk for the next several years.
ConocoPhillips told the Division of Oil and Gas that the 3-D seismic survey will be 155 square miles “of full-fold data, covering nominally one-half” of the Kuparuk River unit. The company said original 3-D datasets were acquired between 1988 and 1990, and as a result of the new 3-D, which will have higher frequency content, closer spacing and longer offset, it expects “significant improvement in stratigraphic and structural resolution at all horizons, both producing and non-producing intervals…”
ConocoPhillips is also drilling a sidetrack lateral on the eastern edge of Kuparuk, the 1D-30L1, from the 1D pad in ADL 25661, to test Kuparuk C4, C3, C2 and C1 sands in lease ADL-28248, outside the boundary of the existing participating area, although inside the Kuparuk River unit. The company said that if the sidetrack, being drilled as a tract operation, is successful, the working interest owners will apply for an expansion of the participating area.
ConocoPhillips plans one-half rotary rig year per year for Kuparuk drilling and workovers with five to seven new penetrations per year. Approximately five coiled tubing drilling wells are planned in 2005 and 2006, the company said, then 10 coiled tubing drilling wells per year for 2007-09, the remaining years of this five-year plan.
