Oil prices rose on Monday, but gains were minimal as investors gauged whether an increase in U.S. drilling and record stockpiles would undermine efforts by producers to cut output and bring the market into balance. Brent futures LCOc1 were up 1 cent at $55.82 a barrel at 0050 GMT, while U.S. West Texas Intermediate crude CLc1 rose 3 cents to $53.43 a barrel. U.S. energy companies added oil rigs for a fifth consecutive week, Baker Hughes said on Friday, extending a nine-month recovery with producers encouraged by higher crude prices, which have traded mostly over $50 a barrel since late November. [RIG/U] The Organization of the Petroleum Exporting Countries (OPEC) and other producers, including Russia, agreed last year to cut output almost 1.8 million barrels per day […]