Enbridge and Enterprise Products Partners
Reversing the pipeline will increase the flow of crude from Cushing, the delivery point of the New York Mercantile Exchange's oil futures contract, to the Gulf Coast.
The reversed line could be in service at an initial capacity of 150,000 bpd by the second quarter of 2012, Enbridge said. Station additions and modifications needed to ramp up flow rates to 400,000 bpd will be completed by early 2013.
Enbridge's acquisition of the stake in Seaway is expected to be completed in December, ConocoPhillips said.
Inventories in the U.S. Midwest have swelled this year due to rising supplies from Canada and North Dakota, helping to drive the premium of Brent crude to U.S. oil futures to record highs over $28 a barrel in October.
The premium of international benchmark Brent crude to U.S. oil futures dropped nearly $3 to below $10 a barrel following the news, the lowest level since March 2011.
In another deal, Conoco also said it will sell its 16.55 percent interest in Colonial Pipeline Co and Colonial Ventures LLC to a subsidiary of pension fund Caisse de Depot et Placement du Quebec.
Conoco's pipeline deals, part of its strategy to shed assets it no longer considers strategic, totaled $2 billion, the U.S. oil company said.
(Reporting by Anna Driver in Houston and Matt Robinson and Mike Erman in New York, editing by Gerald E. McCormick and Jim Marshall)