SEOUL, July 29 (Reuters) - SK Innovation Co Ltd, owner of South Korea's top refiner SK Energy, said on Wednesday that refining margins are expected to improve in the second half of this year due to demand driven by a gradual global economic recovery.

The company posted an operating loss of 440 billion won ($367.44 million) in the second quarter, compared with an operating profit of 494 billion won for the same period a year earlier, it said in an earnings statement. ($1 = 1,197.4600 won) (Reporting by Heekyong Yang and Joyce Lee; Editing by Muralikumar Anantharaman)