Oil prices moved above 78 dollars a barrel in Asian trade today as a weaker US dollar helped boost demand. New York's main contract, light sweet crude for January delivery, advanced 79 cents to 78.26 dollars a barrel in morning trade. The December contract, which expired at the weekend, closed at 76.72 dollars in New York last Friday. Brent North Sea crude for January delivery was up 69 cents to 77.89 dollars.