Oil prices rise as OPEC's output cuts drain stocks

By Christopher Johnson LONDON (Reuters) - Oil prices rose on Tuesday on evidence that the global market was tightening as lower production by OPEC and other exporters drained stocks, but analysts said higher U.S. output could eventually limit gains. Ministers were engaged in a campaign of "bullish rhetoric", talking up their deal to make sure the market responds positively, said Tamas Varga, senior analyst at London brokerage PVM Oil Associates. "Call it a charm offensive or determination to suc