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Endicott — the first offshore Beaufort Sea island
Kristen Nelson
Editor’s Note: See related Northstar story on front cover of this issue. Until Badami, it was the farthest east of North Slope producing fields. Until Northstar starts up next year, it remains the only offshore production island in the Arctic. At 47 acres — compared to five surface acres at Northstar — and connected to shore with a gravel causeway — BP Exploration (Alaska) Inc.’s Endicott field represented thinking on how to develop offshore facilities when it was built in the 1980s.
Startup at Endicott was in 1987. It consists of two manmade islands in the Beaufort Sea northeast of Prudhoe Bay, some two and a half miles offshore. The main production island — with quarters and process facilities — sits at the end of a gravel causeway which provides road and along which an elevated pipeline runs, taking Endicott’s oil to the trans-Alaska pipeline. The secondary drilling island, where a rig currently sits idle, lies along the causeway between the main production island and shore.
Production: Oil and gas reserves In a March 9, briefing at the field, Endicott HSE superintendent Stan Gates and reservoir engineer Mark Sauve said that Endicott has produced more than 400 million barrels of oil to date, from an estimated 1.1 billion barrels of original oil in place.
The sanction case for the $1 billion development, Sauve said, was 350 million barrels. A total of just under 600 million barrels are believed recoverable. The facility currently produces about 40,000 barrels a day from the Endicott, Sag Delta and Eider fields, down from a peak of 115,000 barrels a day in 1992.
Facilities on the island are powered by gas, and the facility is totally self contained with its own power and potable water derived from seawater by reverse osmosis.
Of some 500 million standard cubic feet a day of gas produced, the island uses 30 million and the remainder is re-injected. The Endicott gas resource is estimated at 1.24 trillion cubic feet.
Process facilities The control room at Endicott was state of the art when it was built, control room operator Ken Wood said, but it’s based on a mainframe computer and today’s state of the art controls are based on PCs.
Produced fluid — oil, water, gas — comes into the plant from the wells, Wood said, and three-phase separation is managed out of the control room. After separation, water and gas are re-injected and oil is sent to shore. Production is now about 75-80 percent water, he said.
In addition to separating produced oil, water and gas, Wood said, the facility also deals with voidage — replacing the produced volume in the reservoir each day. In addition to produced water, seawater is treated and injected to fill the void, with each day’s target enough seawater, combined with produced water, to make up the volume produced out of the reservoir.
BTUs — whether used in heating or cooling — are the most expensive thing on the North Slope, Wood said, so Endicott treats cooler Badami oil coming into the Endicott pipeline as a free benefit, using it to cool Endicott oil for pump station No. 1 without use of energy.
The gas turbines which bring in and compress cold air are like jet engines, Gates noted, more efficient when the air is thin and cold. The cutoff temperature for turbine efficiency at Endicott was -10 degrees Fahrenheit, Gates said, so last year the equipment was modified to get flat power out of the machines.
People facilities Workers at Endicott, about 45-50 BP and contractor employees, work 12-hour shifts, two weeks on, two weeks off. Gates said that when the drilling rig is working there are an additional 50 workers housed at the facility. In the early days, with production at 115,000 barrels a day and continuous drilling, he estimated that the facility would have housed 150 workers at a time.
Endicott has a cafeteria, a theater and a recreation center with a running track and a volleyball court. The recreation center provides more than a place to relax. Gates said that back injuries had been a problem at Endicott, but since a mandatory program of stretching and exercises was instituted two years ago, the facility has had no lost-time injuries.
Endicott has a complete medical emergency center and physician’s assistant Noel Choquette said the center works with Providence Medical Center’s emergency room physicians. In addition to treating injuries, the medical center handles collections for routine tests and has mutual aid agreements with the other units on the North Slope for emergencies.
Volunteer fire, medical and spill teams use equipment housed in a heated garage adjacent to the medical center, where a hook and ladder truck and a hose truck sit ready to go next to Endicott’s ambulance.
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