Enterprise Products and Enbridge announced late Thursday that modifications to the Seaway crude oil pipeline allowing it to transport crude oil from Cushing, Oklahoma to the US Gulf Coast have been completed.

The pipeline is in the process of being commissioned, and the first flows of crude oil into the line are expected to begin this weekend, the companies said.

The reversal of the 500-mile, 30-inch diameter pipeline, which had been in northbound service since 1995, provides North American producers with the infrastructure needed to access more than 4 million bpd of Gulf coast refinery demand.

The reversal will initially provide 150,000 bpd of capacity, which is expected to increase to more than 400,000 bpd in the 2013 first quarter with additional modifications and increased pumping capabilities.

In addition to the pipeline, the Seaway system is comprised of a terminal and distribution network originating in Texas City, Texas, which serves refineries locally and in the Houston area.

The Seaway system also includes dock facilities at Freeport and Texas City.