Hours-long toxic gas leak at Pemex oil refinery near Houston far exceeded legal limit

By David Alire Garcia and Erwin Seba

MEXICO CITY/HOUSTON (Reuters) -Pemex's Deer Park oil refinery near Houston discharged 43,500 pounds of highly toxic hydrogen sulfide gas over more than seven hours in a deadly incident earlier this week, according to the Mexican state-owned company's disclosure to a Texas regulator.

The accident on Thursday killed two contract workers while injuring 35 others during work on a unit at the refinery.

According to Pemex's initial report to the Texas Commission on Environmental Quality, the Oct. 10 leak continued for 7 hours and 40 minutes. Over the course of the incident, the hydrogen sulfide discharge exceeded more than 800 times the hourly emission limit for the dangerous gas of 6.89 pounds per hour.

The data from the Texas regulator is dated Oct. 11.

The refinery, which features a crude processing capacity of 312,500 barrels per day, will operate this weekend at a "low level" as Pemex investigates the cause of the leak, the company said late on Friday in a statement.

Houston-based Buzbee Law Firm said it had been retained by "several families impacted by this horrific incident."

Pemex management has operated the facility for nearly three years.

Work was underway on a sulfur recovery unit at the time of the fatal discharge, according to people familiar with the matter.

The Deer Park refinery is a major motor fuels supplier to Mexico, where the government has sought to reduce reliance on gasoline and diesel imports from non-Pemex refiners in a push to be more energy self-sufficient.

Pemex's newly-appointed CEO Victor Rodriguez told reporters on Friday morning that thirteen workers remained hospitalized after being exposed to the leak, while Mexico's energy minister said at the same briefing that she expected the facility to be back to normal operations later on Friday.

But the company walked back that expectation with its latest statement.

"The refinery continues to operate in stable conditions at a low level, a level that will be kept in place during the weekend as long as it's possible to have access to the areas to carry out the corresponding inspections," the company said in its Friday night statement.

Rodriguez, who took over earlier this month, noted on Friday that three or four units had been shut at the refinery following the leak.

The U.S. Chemical Safety and Hazard Investigation Board (CSB), which investigates industrial accidents and makes recommendations to prevent future incidents, has also begun a probe of what it described as a "very serious incident."

CSB said late on Friday that its investigators should arrive at the refinery on Saturday.

Deer Park for decades was operated by oil major Shell, but Pemex took full ownership of the refinery in early 2022, acquiring Shell's 50% stake in what had been a long-standing joint venture.

In 2021, Shell disclosed that it sold its interest in Deer Park to Pemex for some $596 million.

Pemex's domestic refineries have for years suffered major accidents, including explosions and fires, that have caused deaths in Mexico.

(Reporting by David Alire Garcia in Mexico City and Erwin Seba in Houston; Additional reporting by Ana Isabel Martinez; Editing by Diane Craft)