Oil prices dipped slightly on Tuesday but remained near a 2015 peak reached last week as expectations of another rise in U.S. stockpiles and near-record-high Saudi Arabian output were balanced by rising tension in the Middle East. Crude prices have climbed around 18 percent since the start of April due to mounting concern over conflict in Yemen, with the U.S. navy saying on Monday it had sent an aircraft carrier and a guided-missile cruiser into waters near the country. Brent crude for June delivery (LCOc1) was down 7 cents at $63.38 a barrel by 0349 GMT, after settling flat on Monday. U.S.