Enbridge Inc. has exposed a conflict between U.S. refiners and Canadian producers with its proposal to convert the 3 million b/d oil Mainline into a contract transporter for only a few after 70 years as a common carrier for all.

US crude oil imports from Canada

Of 15 total conversion supporters, 10 are U.S. refiners or their marketing arms, according to a filing opposing the change by the 170-company Explorers and Producers Association of Canada (EPAC) to the Canada Energy Regulator (CER).

Three of the five Canadian firms that support Enbridge’s application to switch 90% of Mainline capacity to years-long pipeline contracts from monthly shipping orders have corporate affiliations with U.S. refineries.

“If approved, it will reduce market optionality for Canadian producers, transfer pricing power to...