The outage on the Colonial Pipeline could be exacerbated by a Michigan state order forcing Enbridge Inc.’s Line 5 pipeline — supplying oil to Michigan, Ohio, Ontario and Pennsylvania refineries — to shut down on Wednesday, which could further strain U.S. oil supply. Calgary-based Enbridge has vowed to defy the order and continue shipping oil through the line until forced to close by a court. Analysts believe shutting down Line 5 could cause higher fuel and propane prices in affected areas in the U.S. Midwest and Central Canada as well as potentially thousands of layoffs. Still, the potential for two major pipelines being shut down in the same week shows the stretched energy supply system in North America is increasingly vulnerable to outages, Tran said.