Located in the southern part of the North Sea, the acquisition is close to a gas storage facility Centrica bought in 2003.
The move is part of the company's plan to reduce its exposure to fluctuations in electricity and gas prices, according to Centrica chief executive Sam Laidlaw.
Mr Laidlaw said the move would have an impact on UK gas prices.
He added: "This deal underlines our commitment to invest in new energy supplies from the North Sea at a time when existing North Sea production is in decline."
Centrica expects to extract 107 billion cubic feet of gas from its expanded field, 79 billion of which are attributed to York acquisition.
Meanwhile, British Gas was the first UK energy firm to announce gas price cuts.
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