Сrude futures chalked up gains Monday in light trading as markets responded to speculation that U.S. refineries might be unable to match demand in the later half of the year. Light, sweet crude for June delivery rose 26 cents to $51.22 per barrel in morning electronic trading on the New York Mercantile Exchange. Unleaded gasoline gained a cent to trade at $1.4870 a gallon, while heating oil climbed half a cent to $1.4368 a gallon. On London's International Petroleum Exchange, June Brent crude futures were up 31 cents to $51.08 a barrel. "The prominent feature is a lack of news" in an uneventful European market, said Adam Sieminski, an oil price strategist at Deutsche Bank in London. "I expect crude prices to stay near the $50 dollar threshold, or even dip below it in the second half as inventories rise," Sieminski said.