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Kuparuk still ranks as major U.S. field ConocoPhillips lays out development plans for upcoming year; main field and satellites combined for 121,900 barrels a day in 2011 Wesley Loy For Petroleum News
The Kuparuk River oil field has given a lot — and operator ConocoPhillips is aiming to take a lot more.
Cumulative production through May from Kuparuk, including its satellite fields, was nearly 2.47 billion barrels of crude oil, Alaska Oil and Gas Conservation Commission figures show.
In 2011, the main Kuparuk field produced an average of 91,400 barrels of oil per day gross, with the satellites adding another 30,500 barrels, ConocoPhillips says.
Kuparuk is the second-largest field on Alaska’s North Slope, behind only Prudhoe Bay, which has produced more than 12 billion barrels.
Nationally, Kuparuk’s proved reserves ranked sixth on the Energy Information Administration’s most recent (2009) listing of the Top 100 U.S. oil fields, with Prudhoe at No. 1.
Aside from ConocoPhillips, the other major Kuparuk owner is BP, with Chevron and ExxonMobil holding small shares.
In late June, ConocoPhillips submitted updated development plans to the state Department of Natural Resources for Kuparuk and its satellites, which include West Sak, Tabasco, Tarn and Meltwater.
The plans review work done during 2011, and discuss drilling and other activity planned for the upcoming period of Aug. 1 through July 31, 2013.
The Kuparuk field Located west of the Prudhoe Bay field, Kuparuk was discovered in 1969 and began production in late 1981, peaking at 322,000 barrels per day in 1992. The producing reservoir is composed of Cretaceous-age Kuparuk sands at depths of 5,500 to 6,500 feet.
Processed oil from Kuparuk and its satellites is piped 28 miles to Pump Station 1, the beginning of the trans-Alaska pipeline.
As of the end of 2011, the main Kuparuk field had 866 active wells on 44 drill sites. The wells included 476 producers and 390 wells for injecting water or gas below ground to maintain reservoir pressure and enhance oil production.
Among accomplishments for 2011, ConocoPhillips says it implemented a 12-well coiled-tubing drilling program to generate a peak incremental oil rate of about 2,600 barrels of oil per day.
“Forty-six laterals were drilled and completed in these wells,” the Kuparuk development plan says.
The company is focused heavily on the day, fast approaching, when it will need to import natural gas from the neighboring Prudhoe Bay field meet Kuparuk’s needs. The best technical estimate for when gas imports will need to begin is 2015, the plan says.
“The plan is to utilize imported Prudhoe gas as fuel gas only and not introduce any of this gas into the production system, either by injection or in the gas lift system,” the plan says. “This is due to corrosion concerns relating to the relatively high CO2 content (10-12%) of Prudhoe gas.”
Investment and drilling ConocoPhillips told DNR its development plan “assumes a continuation of the current business climate and a continued increase in field operating costs.”
It added: “There are many challenges to delivering on our proposed plan forward and those challenges would be reduced by a fiscal change in Alaska.”
Considerable drilling opportunities exist in Kuparuk, the company says.
For example, a “large portfolio” of candidates prompted ConocoPhillips to commission and contract a coiled-tubing rig that’s been drilling wells continually since May 2009. Nabors Alaska owns and operates the CDR2-AC rig.
The company is conducting 4D, or time lapse, analysis of seismic data collected over a small area of about 60 square miles, and says preliminary results are “encouraging.”
“A breakthrough in 4D imaging and analysis would potentially lead to additional seismic data acquisition, improved understanding of reservoir dynamics, and optimized oil recovery at Kuparuk,” the development plan says.
For the upcoming year, 12 or 13 coiled-tubing drilling sidetrack projects and five rotary sidetracks are planned.
As for exploration, ConocoPhillips drilled an appraisal well, the Shark Tooth No. 1, in early 2012 in the southwest area of the Kuparuk River unit.
On the maintenance front, the company in 2011 completed an “in-situ internal pipe coating pilot project.” The coating was successfully applied, and additional pilot projects could be done on larger or longer lines as a possible alternative to pipeline replacements.
Overall, ConocoPhillips suggests Kuparuk and its satellites have “at least another 25 years of production” left. But major capital investment will be needed to upgrade Kuparuk’s electronic equipment, turbines, utilities, airstrip and camp.
The West Sak field ConocoPhillips submitted development plans for each of Kuparuk’s four satellite fields.
The most productive of these in 2011 was West Sak, a shallow heavy oil deposit overlying the Kuparuk reservoir. Discovered in 1971, West Sak’s core area holds 1.5 billion barrels of oil, but the oil is cold, thick and difficult to produce.
ConocoPhillips managed an average of 15,718 barrels a day from West Sak in 2011. Cumulative production from the field at year’s end stood at 56.6 million barrels.
West Sak had 60 active wells, 41 of them producers, on six drill sites at the end of 2011.
Waterflooding is the main enhanced recovery method used at West Sak.
ConocoPhillips has tried a variety of drilling techniques, including horizontal laterals that undulate through oil-bearing sand layers. This design has fallen out of favor, however, due to problems such as “loss of net pay exposure while drilling through intervening shales,” the West Sak development plan says.
A 31-well development was completed on drill site 1J in 2007, and now “the pace of future West Sak development has slowed,” ConocoPhillips says, as 1J and other recent developments are evaluated.
One production well might be drilled in the coming year on drill site 3K, the company says.
Other satellites Tabasco is another Kuparuk heavy oil satellite. Tabasco began producing in 1998, with 12 development wells drilled to date. The field averaged 1,608 barrels a day in 2011, and cumulative production stood at nearly 17 million barrels at year’s end.
Two more satellites, Tarn and Meltwater, are situated southwest of Kuparuk.
Brought online in 1998, Tarn features 63 development wells on two drill sites. Average daily oil production was 10,500 barrels a day in 2011, with cumulative production at 105 million barrels by year’s end.
ConocoPhillips reports “the first multi-stage fractured well in the Tarn field” was completed in June 2011, and early production results were favorable with an average rate in December of 494 barrels per day.
Tarn oil is prone to paraffin deposition, and dealing with that has been a pain, the development plan indicates.
But ConocoPhillips sounds bullish on the field’s prospects.
“Reservoir simulation studies are ongoing to understand the benefits of continued infill drilling and development of the peripheral areas” of Tarn’s two drill sites, the plan says. “Recent wells have been highly successful at demonstrating the potential of the different flanks of the field.”
The Meltwater satellite began production in 2001, and features 19 development wells on one drill site. Production averaged 2,671 barrels a day in 2011, and cumulative production at year’s end stood at 16.1 million barrels.
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