(Adds data on size relative to U.S. imports of Canadian crude)
NEW YORK, Oct 30 (Reuters) - The 1.2-million-barrel-a-dayCapline crude pipeline, the biggest in the mainland UnitedStates, is reviewing its future operations, its owners said onThursday, as the North American oil boom upends the flow acrossthe continent.
Shipping volumes on the pipeline, which runs south to northfrom the Gulf Coast to Illinois, have fallen steeply in recentyears as Midwestern refiners tap into the growing supply ofCanadian and North Dakota crude to replace costly imports viaCapline.
Traders and analysts have speculated for several years thatthe line, which is operated by Marathon Petroleum Corp, could be reversed to carry Canadian crude to U.S. Gulf Coastrefineries, allowing it to increase throughput.
A reversal of the Capline could fill a void left by thestalled Keystone XL pipeline. Changing the direction of theCapline would have significant impacts, potentially allowingcheap Canadian crude to further displace heavy crudes the UnitedStates imports from Latin America and the Middle East.
In recent months, Gulf Coast refiners have bought about 5percent of the 2.75 million barrels per day of Canadian oilimported by the United States, U.S. government data show. Thoserefiners are hungry for more Canadian oil, and the Capline'scapacity amounts to about 44 percent of existing U.S. imports ofCanadian crude.
"This analysis is being conducted to address the expandingcrude oil supply in North America and the significant changes incrude oil demand patterns," Marathon Petroleum said in astatement.
Marathon and co-owners Plains All American Pipeline LP and BP Plc said they planned to complete thestudy in the first quarter of 2015.
Marathon Chief Executive Officer Gary Heminger said inDecember that the company might consider reversing the pipeline,but that another pipeline would be needed to carry crude fromsouth to north.
The owners also said they would consider connecting Caplineto the proposed Diamond pipeline, which will run from thestorage hub at Cushing, Oklahoma, to Valero Energy Corp's Memphis, Tennessee, refinery. That would provide analternate source of crude for the Valero plant, a major user ofthe Capline.
The 632-mile 40-inch pipeline includes more than 10 millionbarrels of storage capacity and 16 mainline pumping stations. Itoriginates at St. James, Louisiana, the delivery hub for LightLouisiana Sweet crude. (Reporting by Jessica Resnick-Ault; Editing by Lisa Von Ahn andLeslie Adler)
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