Enterprise Products Partners LP, which recently received permission to export unrefined light oil pumped in the U.S., said it purchased a stake in an oil-storage business that would better position the company for shipping fuel.

Enterprise bought the majority of Oiltanking Partners LP and proposed buying the rest of the marine-terminal owner in a two-step deal valued at $5.8 billion.

Oiltanking's assets include oil storage tanks and dock space on the Texas Gulf Coast that will increase Enterprise's ability to export refined fuels and, if the U.S. allows it, greater quantities of crude oil.

"This combination would benefit our producing and consuming customers by enhancing their respective access to supplies, domestic and international markets and storage," Michael Creel, chief executive of Enterprise's general partner, said Wednesday.

The companies have worked together since 1983, and Enterprise is Oiltanking's largest customer.