MEXICO CITY, March 22 (Reuters) - Mexican state energy company Pemex put off urgent repairs and maintenance at an important offshore platform for months, resulting in methane spewing into the atmosphere, according to internal documents and three sources familiar with the infrastructure.

Methane, the main component of natural gas, is a much more potent driver of global warming in the short term than carbon dioxide because it traps more heat in the atmosphere, tonne for tonne.

New data from the United Nations Environment Programme's (UNEP) International Methane Emissions Observatory showed that the problematic Pemex platform in the Gulf of Mexico leaked methane as recently as December 24.

Reuters previously revealed that the Zaap-C platform, one of the most important in the Gulf of Mexico, had leaked on at least 25 days between January and November 2023.
The five internal documents, seen by Reuters, show for the first time that Pemex has been aware of components at the platform that were beyond repair and several other deficiencies related to the infrastructure since at least June.

Pemex needs to install two new turbo compressors at the platform, various pipelines, connecting infrastructure and a firewall for safety reasons, an evaluation by Pemex from January shows. The turbo compressors help compress the gas so it can be reinjected into the field.

Three sources who work on the infrastructure said that when key components fail, the platform's flare goes off and methane is released into the atmosphere. It is not redirected to another platform nor reinjected into the field, they said.

A flare is meant to burn off the methane component of gas that comes to the surface during oil exploration and production.

The Pemex documents include internal proposals for changes, infrastructure plans and extracts from a database detailing the composition of gas. None of them have previously been reported.

Pemex, which is responsible for the infrastructure, has in the past denied these large methane leaks at the platform. It did not respond to repeated requests for comment.
The president's office, the energy ministry, the oil regulator and the environmental regulator, also did not respond.

Engineers have on several occasions urged Pemex to replace the faulty parts and make other urgent repairs, the three sources said, adding that other parts of the Gulf of Mexico infrastructure also lack maintenance.

The sources - all engineers - said the faulty infrastructure remains in place, and the January evaluation still lists it as needing replacements and repairs, more than six months after the problems were flagged in the reports seen by Reuters.

It would take about three months to carry out the works, one of the sources said, adding that it would also mean halting at least some part of production.

MEXICO NOTIFIED OF LEAKS

Last month, Reuters revealed that a U.N. agency had notified Mexico of repeated methane leaks from the platform.

Scientists around the world have in recent years joined the dots on flares and methane emissions, demonstrating that once a flare is out - and production is not halted - vast volumes of methane are almost always released into the atmosphere.

"This is something for which we've recorded evidence in different parts of the world," said Daniel Zavala, a senior scientist at the Environmental Defense Fund who has extensively researched emissions in Mexico.

"It was easy for operators to say: if you cannot see burning happening, it means that no gas is coming out," Zavala said. "Until recently, we didn't have a way to check."
When the flare works as intended, Zaap-C flares some 300 million cubic feet of gas per day, one of the sources said.

Reuters reviewed internal Pemex data that shows that 17% of this gas is pure methane and 73% of which is nitrogen, a harmless gas that is plentiful in the atmosphere. The rest is composed of other gases and impurities.

Zavala said that with such vast volumes of gas, even the relatively low percentage of methane was problematic for both the environment and the potential safety of workers.
Pemex employs some 300 workers on the Zaap-C platform alone, and lingering methane could cause fires and explosions.

Infrastructure to burn off methane from gas that comes to the surface as part of oil production was initially put in place as an industrial safety measure, long before the environmental impact of the greenhouse gas was widely known.

In the Gulf of Mexico, Pemex has long either burnt off the gas or reinjected it into the fields - a way to recover more oil and compensate for lower production as it is being depleted.

Pemex has been reluctant to make significant investments in infrastructure relating to old fields, said three other sources working at the company's exploration and production arm and one source at the regulator.

Halting production at the world's most indebted energy company would be problematic, the sources said, because it would affect output and lead Pemex to miss ambitious targets set by President Andres Manuel Lopez Obrador, who seeks to make the country self-sufficient in energy.

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Reporting by Stefanie Eschenbacher and Allison Martell; editing by Claudia Parsons