A deep-freeze in Canada and Northern U.S. is disrupting oil flows, causing a surge in crude prices just as American stockpiles are declining. With temperatures from North Dakota to Northern Alberta below zero Fahrenheit (-18 Celcius), TC Energy Corp.’s Keystone pipeline was shut late Tuesday, with the cold slowing oil flows and making it hard to restore service. In North Dakota’s Bakken shale, production has started to succumb to the freeze, sending local crude prices to their highest since November. Canadian oil has also jumped.