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The total proven reserves of the Skifska gas field are around 8.875 trillion cubic feet ( 250 × 109m ³ ) , and production is slated to be around 550 million cubic feet/day ( 15 × 106m ³ ) in 2015 .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
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