The company, which pumps about 3.4 million barrels a day of crude and exports just over half to the United States, said it was unclear how the evacuations would affect production.
In the town of Alto Lucero, 295km east of Mexico City, officials prepared to secure a nuclear power plant against the storm's wind and rain.
The storm was about 340km east-north-east of Veracruz with maximum sustained winds of 95kmph, said the US National Hurricane Center at 9am (EST) this morning. It was expected to become a hurricane later today.
Tropical Stan, which formed on Sunday, is the 18th storm of the season. It hit the Yucatan Peninsula and was moving through the Bay of Campeche on Monday toward a second landfall on the Mexican coast tomorrow.
Meanwhile, a leading forecaster said yesterday the Atlantic hurricane season was expected to produce at least two more hurricanes in October, which would take the season total to 21 and tie the record for a single season set in 1933.
In a monthly forecast update, Colorado State University’s Dr William Gray said October should experience three tropical storms, adding to what is already one of the busiest and most destructive seasons on record.
He said two of the three October storms would become hurricanes, one of which would be a major hurricane with winds over 177kmph. The season has already endured five major hurricanes, which is double the long-term average for a season.
Gray said factors contributing to the recent busy hurricane seasons included warmer Atlantic sea surface temperatures, lower surface pressures and low wind shear.
But he did not believe human-induced global warming had caused the recent increases in Atlantic activity. Gray attributed the increases to long-period natural climate alterations, already having occurred many times in the past.
"If global warming were the cause ... we would expect to see an increase in tropical cyclone activity in the other storm basins as well, such as in the West Pacific, East Pacific and Indian Ocean basins," he said.
"This has not occurred."
