Oil recovery at Troll: aiming at magical IOR figures
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With four drilling rigs in continuous operation for eight years, Troll A is setting new standards for oil recovery. The goal is to drill twelve wells each year, a world-class achievement.
As a gas producer since 1996, Troll A in the North Sea has a production capacity and lifetime that far exceed all other fields on the Norwegian shelf.
The first Plan for Development and Operation (PDO) for oil recovery on Troll B predicted only about 55 million standard cubic metres of recoverable oil resources. But in February this year, production from the field exceeded 222 million standard cubic metres.
The current ambition is to recover a total of 333 million cubic metres of oil (about 2.1 billion barrels).
"About 300 of these we know how to recover. As for the rest, we’ll have to think of something smart," says production vice president for Troll, Rune Adolfsen.
Balances with oil
The Troll field was regarded solely as a gas field. But bold engineers saw the opportunity to recover the thin oil zone. The gas lies like a cover over an oil stratum that represents assets worth billions—if recovered in time.
And there is still a lot of oil left in the oil column on Troll. The two platforms, Troll B and Troll C, have available capacity for oil—and this might be of interest for surrounding licences. The development of the area north of Troll is particularly interesting.
With its stable oil and gas production, Troll is a significant contributor to our strategy to be able to deliver 2.5 million oil equivalents up to 2020.
"Now, the authorities are aware of the volumes present at Troll and want them to be recovered. We now assume a recovery rate of more than 50 per cent for the Troll oil, and that is high,” says Adolfsen. "Maybe we’ll have a Skrugard discovery again on Troll, or nearly 600 million barrels. There may be several pleasant surprises on Troll."
Adolfsen points out that since the beginning in 1995—1996, Troll has already joined the ranks of mature fields. With an ample growth in reserves and solid technical design, the field can produce until 2063.
"While we have been recovering the oil we have also made changes in facilities and infrastructure, including new living quarters on Troll A and ample updating and maintenance of Troll B and C,” he says. He particularly emphasises that Equinor has had solid support from its licence partners Shell, ConocoPhillips, Petoro and Total.
"We have been joined by the heavyweights on the Norwegian shelf in developing Troll. They have backed up the long-term perspective, joined in the commitment and challenged us in good and constructive dialogues. And when at the same time the authorities are a driving force for improved recovery, we have good reason to be satisfied,” says Adolfsen.