U.S. offshore oil and natural gas producers are restarting production operations with Tropical Storm Don long over, data from Gulf of Mexico energy regulators showed on Sunday.

The U.S. Bureau of Ocean Energy Management said 6 percent, or 84,072 barrels per day, of oil output remained offline, down 4.9 percentage points from Saturday.

BOEM also said 3.5 percent of daily natural gas output, or 186 million cubic feet of natgas, remained shut in, down 3.1 percentage points from Saturday.

Among those that had restarted all shut production was Anadarko Petroleum Corp, which had closed and fully evacuated six Gulf platforms.

All back up and running, Anadarko spokesman John Christiansen said.

BOEM's statistics were based on reports from 17 companies on Sunday, the agency said.

Some producers, including Shell Oil Co, had yet to report publicly whether they had restarted shut production.

Chevron Corp said on Sunday it had restarted oil and gas production shut in for the storm and was re-staffing Gulf operations. The company never disclosed how much output was shut or how many workers were evacuated.

Exxon Mobil Corp said it was returning evacuated workers to Gulf operations, but about 8,000 barrels per day of oil and 50 million cubic feet per day of natural gas output remained shut in.

Don was the first threat to Gulf energy infrastructure in the 2011 hurricane season, but the storm's path came nowhere close to the basin's major concentrations of oil and natural gas platforms.

A westward-moving weather system about 575 miles east of the northern Windward Islands had a near 100 percent chance of becoming a tropical cyclone in the next two days, the National Hurricane Center said on Sunday. That system will be named Emily if it strengthens into a storm or hurricane.

The Gulf's daily output is about 1.4 million barrels of oil and 5.2 billion cubic feet of natgas, according to BOEM data.

Don hit shore late on Friday 40 miles south of Corpus Christi and quickly dissipated.

The three major refiners with plants in Corpus Christi -- Valero Energy Corp, Flint Hills Resources and Citgo Petroleum Corp -- reported no Don-related disruptions.

Overall, the Gulf accounts for 30 percent of U.S. oil production and 12 percent of natural gas output, according to BOEM. The Gulf Coast also is home to 40 percent of U.S. refining capacity, and 30 percent of natural gas processing plant capacity.

(Editing by Dale Hudson)