Royal Dutch Shell PLC and the state-owned Saudi Arabian Oil Co. have announced that they'll split the assets of a U.S. venture that includes America's biggest oil refinery.

The two companies made the announcement late Wednesday about Motiva Enterprises LLC, which formed in 1998 as a 50-50 venture between both firms.

The statement said a Saudi Aramco affiliate will retain the Motiva name and full control of the Port Arthur, Texas, refinery. The U.S. Energy Information Administration says that's America's biggest oil refinery, producing some 603,000 barrels a day.

The Saudi Aramco affiliate also will keep 26 distribution terminals. Shell will get sole ownership of refineries in Norco and Convent, Louisiana, as well as nine distribution terminals.

Saudi Aramco, the world's biggest oil producer, is considering offering company shares publicly.