Pipeline firm Plains says Permian volumes grew in Q1, constraints appear

NEW YORK, May 8 (Reuters) - Plains All American Pipeline LP said on its first quarter earnings call that Permian crude oil transportation volumes grew about 750,000 barrels per day in the quarter compared with a year earlier: * Production in the Permian basin is currently exceeding expectations and a recent widening of Permian crude differentials is a positive indicator for fee-based revenue on Permian systems. * "Our 2018 guidance incorporated an expectation that Permi