Residents of the northernmost city in America recently voted to rename their city Utqiagvik. But, for now, their local energy source is still called the Barrow gas fields.
Contractors working for the federal government discovered the South Barrow, East Barrow and Walakpa fields on separate expeditions into the northwest corner of the North Slope Borough between the late 1940s and the 1980s. The three gas fields powered the city of Utqiagvik for decades before noticeable declines prompted municipal leaders to push for a re-development campaign. A pair of voter-approved bonds allowed the city to launch a $92 million rejuvenation program in 2011. The city commissioned the Savik 1 and 2 wells at East Barrow and the Walakpa 11, 12, and 13 wells at Walakpa. By improving deliverability, Utqiagvik can now use gas for its energy needs even during cold snaps or maintenance activities, instead of switching to diesel as an alternative.
South BarrowThe U.S. Navy discovered the South Barrow field with the 2,505-foot South Barrow No. 2 well in 1948, during its initial wave of National Petroleum Reserve-Alaska exploration.
Production began the following year. Drilling continued for decades, with 13 new wells drilled and one existing well deepened by 1987, according to the Alaska Oil and Gas Conservation Commission. Production peaked at some 3.5 million cubic feet per day in November 1981. The field is now used primarily to meet peak demand during the winter.
According to the AOGCC, the South Barrow field had produced more than 23.7 billion cubic feet of gas at the start of 2014, and cumulative production was unchanged by the end of June 2016. Geologists originally expected the field to produce some 32 bcf.
East BarrowThe U.S. Geological Survey discovered the East Barrow field with the South Barrow No. 12 well in 1974, during the second wave of oil and gas exploration in the NPR-A.
Production began in December 1981. Drilling continued through 1990, with eight wells total. East Barrow production peaked at some 2.75 million cubic feet per day in 1984.
According to the AOGCC, cumulative production at East Barrow was 8.9 bcf at the start of 2015, 9.1 bcf at the start of 2016 and 9.2 bcf by the start of 2017, suggesting a relatively steady rate of production with occasional fluctuations caused by demand.
The current cumulative total is nearly 50 percent above the originally estimated 6.2 bcf in place for the East Barrow field. The city of Utqiagvik attributes the productivity to methane hydrates - molecules of gas trapped in cages of ice and released through pressure changes. Drops in pressure occur naturally during the aging process of a field.
WalakpaWorking under a Navy contract, Husky Oil discovered the Walakpa field with the 3,666-foot Walakpa No. 1 well in the 1980s. Production began in the early 1990s. The field has peaked above 5 million cubic feet per day numerous times, including in early 2013.
Today, Walakpa produces the majority of the gas delivered to Utqiagvik.
According to the AOGCC, cumulative production at Walakpa was approximately 26.9 bcf by the start of 2015, approximately 28.3 bcf by the start of 2016 and approximately 29.7 bcf by the start of 2017, suggesting steady annual production rates in recent years.
The South Barrow and East Barrow reservoirs have a stratigraphic setting similar to the Alpine oil field. Walakpa is in the Pebble Shale unit, a major North Slope source rock.