May 28 (Bloomberg) -- Motiva Enterprises LLC, a joint venture of Royal Dutch Shell Plc and Saudi Aramco, reported a fluid catalytic cracker upset at its Norco refinery in Louisiana yesterday, according to a parish official.

Shell reported the upset to the St. Charles Parish Department of Homeland Security and Emergency Preparedness at 11:38 a.m. yesterday, Steve Sirmon, a coordinator for the agency, said in a telephone interview. There was flaring, he said. No offsite impact was reported and no protective actions were required.

A mechanical malfunction caused the upset and flaring, said Sergeant Markus Smith of the Louisiana State Police. “They notified us just before midnight last night that they had ended the flaring process and everything was pretty much back to normal,” he said.

An all-clear was called in to the parish office at 11:57 a.m., according to Sirmon.

The refinery is designed to handle 75 percent Louisiana crudes and 25 percent foreign crudes, according to the company Web site. Daily production is generally 170,000 barrels of gasoline, 46,000 barrels of jet fuel and 50,000 barrels of diesel.

To contact the reporter on this story: Aaron Clark in New York at aclark27@bloomberg.net

Last Updated: May 28, 2009 08:39 EDT