Oil prices edged higher on Thursday with the market mood switching to relief as OPEC forecast a supply deficit next year, from doom and gloom over data showing a surprise increase in U.S. crude inventories Inventories of petroleum products also increased with gasoline stocks surging by more than 5 million barrels and distillates gaining a bi t over 4 million barrels – with both more than double expectations. The Organization of the Petroleum Exporting Countries (OPEC) on Wednesday said it now expected a small deficit in the oil market in the next year, suggesting the market is tighter than previously thought – even before the latest pact with other producers to curb supply takes effect.