One $400-million project involves increasing capacity on Enbridge's Canadian mainline between Hardisty, Alta. and the border.
The other, with a pricetag of $200 million, would expand part of the Lakehead system between Neche, N.D., and Superior, Wisc.
Both projects would boost pipeline capacity by 230,000 barrels per day by increasing pumping horsepower, rather than constructing new pipe.
The two projects are expected to come into service in 2015, subject to regulatory approvals.
Enbridge is a major player in the North American energy market where it operates the world's longest crude oil and liquids pipeline system. The company also has a significant and growing natural gas gathering, transmission and midstream business and an increasing involvement in power transmission.
The expansions announced Friday are the latest to boost the amount of crude that flows through Enbridge's vast North American crude oil system.
In November, Enbridge said it was planning a $1.8-billion pipeline between Edmonton, a key oilsands hub, and Hardisty. That new line will initially be able to carry 570,000 barrels per day but has the potential to be expanded to 800,000 barrels.
Construction could begin as early as the first quarter of 2014, with startup targeted for mid-2015.
In December, Enbridge and its U.S. affiliate announced they were spending $6.2 billion on a string of projects to bring growing volumes of Alberta and North Dakota light oil to market.
The light oil market access program will see an additional 400,000 barrels per day of light oil flow to refineries in Ontario, Quebec and the U.S. Midwest.
Also on HuffPost