By Nia Williams and Ruhi Soni (Reuters) -Canada’s Imperial Oil on Friday booked a first-quarter profit boosted by soaring global oil prices, and announced plans for a substantial issuer bid (SIB) that will involve buying back up to C$2.5 billion ($1.95 billion) of its common shares. News of the SIB helped offset lower-than-expected production for the quarter, after extreme cold weather in northern Alberta triggered an extended unplanned outage at the company’s huge Kearl oil sands mine. Imperial’s shares were last up 1.5% on the Toronto Stock Exchange at C$65.1. Oil companies have been benefit…