HOUSTON, Sept 14 (Reuters) - Energy companies, ports and refiners on Monday were racing to complete shut-downs as Tropical Storm Sally took aim at the central U.S. Gulf Coast with soaking rains and high wind.

Sally was forecast to sock Louisiana and Mississippi with up to 85 mile per hour (137 kph) winds and drop 8- to 16-inches (20-40 cm) of rain, causing widespread flooding. Officials in the two states issued mandatory evacuations for residents in low-lying areas.

The Louisiana Offshore Oil Port, the nation's largest offshore oil export terminal, suspended operations of its marine facility, which loads and unloads crude oil on supertankers.

Chevron Corp shut its Empire and Fourchon oil terminals in Louisiana while the U.S. Coast Guard imposed travel restrictions on parts of the Mississippi River in New Orleans.

The Alliance oil refinery, which processes 255,000 barrels of oil per day (bpd) at a site on the coast of Louisiana, was shutting down, said operator Phillips 66.

Further west, Royal Dutch Shell Plc was continuing normal operations at its 227,400-bpd Norco and 211,146-bpd Convent, Louisiana, refineries.

BP Plc, Chevron, Equinor and Murphy Oil all evacuated some offshore workers from production platforms, the companies reported. Royal Dutch Shell curtailed production at its Olympus platform and halted some offshore drilling operations,

U.S. Gulf of Mexico offshore oil production delivers about 17% of U.S. crude oil and 5% of U.S. natural gas output.

As much as 1.5 million barrels per day of oil was shut in by Hurricane Laura last month.

(Reporting by Erwin Seba and Gary McWilliams; Editing by Steve Orlofsky)