Oil prices were little changed for a third session on Tuesday, with investors searching for direction as concern over rising U.S. shale output offsets production cuts by OPEC and non-OPEC members. As of 0545 GMT, brent crude was down 11 cents, or 0.2 percent, at $55.90 a barrel, with a firmer dollar, unchanged against a basket of other currencies, putting some pressure on dollar denominated oil prices.