HOUSTON, July 5 (Reuters) - Tropical Storm Beryl is expected to have little impact on U.S. offshore oil and gas production, energy companies said on Friday while evacuating personnel from some facilities out of caution.

Beryl was downgraded from a hurricane and shifted over Mexico's Yucatan Peninsula with maximum sustained winds dipping to 70 mph (113 kph), the U.S. National Hurricane Center said.

U.S. Gulf of Mexico offshore production of about 1.8 million barrels per day accounts for about 14% of total U.S. crude output, according to data from the U.S. Energy Information Administration. Any impact on supplies could push up prices of U.S. oil and offshore crude grades.

Oil major Chevron Corp, among the biggest U.S. offshore producers, said production from its operated assets remained at normal levels, adding that it evacuated nonessential personnel from some of its Gulf of Mexico facilities.

The company said it demobilized personnel at its Anchor project, where first production is expected in the third quarter.

Producer Murphy Oil Corp said it did not expect any impact on operations and had not evacuated personnel. Hess Corp said it did not expect any impact to its Gulf facilities.

Occidental Petroleum said it was monitoring the storm's path, adding that it had plans to prepare facilities for weather-related events.

On Thursday, Shell said it evacuated staff at its Perdido facility in the U.S. Gulf and safely shut in production. At its Whale facility, which is not scheduled to begin operations until later this year, it evacuated all personnel. Some drilling operations in the area were paused.

Texas gasoline and diesel markets are well-stocked, so no significant supply disruption is expected for the long term, fuel distributor Mansfield Energy wrote in an email to clients.

LNG producer Cheniere Energy said there was no impact to operations and it was monitoring the storm's development.

The U.S. Coast Guard implemented Condition Whiskey, which can limit ship traffic, for the Port of Brownsville along the U.S.-Mexico border and the Port of Corpus Christi in south Texas on Wednesday. Whiskey is set when gale force winds are expected to arrive at the port within 72 hours.

(Reporting by Arathy Somasekhar and Curtis Williams in Houston; Editing by Rod Nickel)