By Arathy Somasekhar and Georgina McCartney HOUSTON, Jan 6 (Reuters) - A full-scale resumption of Venezuelan oil exports would benefit refiners in the United States and lower their fuel production costs, with the refineries capable of absorbing most of the roughly 1 million barrels per day of crude that would trade freely if U.S. sanctions on the ​South American country are removed. The losers would be Canadian companies that sell a similar heavy oil as Venezuela, and small Chinese refiners, which would ...