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The project was initially developed by Spanish firms Repsol and Gas Natural , but their contract was terminated in 2007 by the Algerian state oil company Sonatrach , which elected to pursue the project on its own .
 Repsol, Gas Natural, Sonatrach
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Repsol, Gas Natural, Sonatrach