Growing Body of Research Suggests Offshore Oil’s Methane Pollution Is Underestimated

Flying 10,000 feet above the Gulf of Mexico, in a plane outfitted with infrared imaging equipment, researchers could see methane gas bubbling under water, likely from an undetected pipeline leak. 

Over the course of several flights in 2021, they spotted frequent gas plumes from platforms, storage tanks, and pipelines offshore, leading the team to believe that the 151 platforms near the Louisiana coast had a much higher methane leak rate than what’s been measured for onshore oil and gas production.

“I think the bottom line message in this study is there’s a lot of emissions in the shallow waters that are currently unmeasured,” said Riley Duren, the CEO of Carbon Mapper and coauthor of the nonprofit’s 2022 study of offshore methane emissions

New technologies are allowing for actual measurements of oil and gas methane emissions like never before, whether from leaks or intentional flaring and venting. So far, much of that attention and push for accountability has been focused onshore, while operators claim that drilling offshore has much lower emissions. But researchers are starting to uncover a body of evidence showing why that may not be true.

A BSEE inspector prepares to land for a scheduled pre-production inspection, Feb. 2, 2022, on a platform approximately 100 nautical miles off the coast of Houma, Louisiana. Credit: BSEE, public domain

About 15 percent of U.S. oil production and 1 percent of U.S. natural gas production comes from federal leases in the Gulf of Mexico, according to the Bureau of Ocean Energy Management. Far from land and oversight, it’s a wild west that makes it easy for companies to fudge numbers and avoid accountability from regulators who acknowledge they’ve fallen short, even as questions emerge about how methane emissions may be contributing to helicopter crashes around oil and gas platforms. 

The rise in natural gas prices has incentivized some onshore companies to try to quantify how much money they’re losing to leaky systems by using infrared cameras capable of detecting methane, the primary ingredient in natural gas and a potent contributor to climate change. Operators in the Permian Basin in Texas and New Mexico, where 40 percent of U.S. oil and 15 percent of U.S. gas is produced, have been surprised to find that about 4 percent of the natural gas they pulled from the ground was leaking into the atmosphere. 

By comparison, Duren and his colleagues have detected natural gas loss rates above 23 percent in the shallow waters of the Gulf, though because offshore production is so much lower, the total volume of lost gas is likely much higher onshore. Still, researchers emphasize that the high rate of methane leakage underscores the major climate impact that reducing those leaks could have. 

Problems with Oversight

The U.S. Bureau of Safety and Environmental Enforcement (BSEE), which regulates the offshore energy industry, has acknowledged gaps in accountability that could be enabling more pollution, such as unverified self-reported emissions numbers and flyover inspections that fail to detect pipeline leaks. The agency has also fallen short in past efforts to enact more stringent methane pollution control measures, even when platform emissions caused helicopter crashes. 

For years, federal agencies have known that relatively low levels of methane gas in the air can cause engine failure in most helicopters operating offshore, but they failed to implement regulatory changes that would require methane detection systems to alert helicopter pilots and other workers of the presence of the colorless, odorless gas. (Once on land, utility companies add a chemical that smells like rotten eggs to natural gas to make it easier to detect dangerous gas leaks.)

In June, the Office of the Inspector General (OIG) warned BSEE that its inspection process didn’t detect when a fossil fuel company “may have manipulated or misreported” methane emissions data across four platforms in the Gulf of Mexico over a five year period. The Inspector General’s Office investigated that oil company following a confidential tip that venting and flaring limits were routinely exceeded from its platforms on federal leases. As a result, the company avoided paying royalties on the gas and owed the federal government $712,857.82, which was billed to the company following the report.

During the investigation, the Inspector General’s Office reviewed venting and flaring reports by the fossil fuel company — which was not named in public documents — and found evidence of manipulated emissions numbers. Most energy companies working in the Gulf are drilling for oil, of which methane is a byproduct. Natural gas reserves in the shallow waters of the Gulf have been depleted and drilling for natural gas in deeper water has been uneconomical, according to the Bureau of Ocean Energy Management

The silhouette of an offshore oil and gas platform and boat in the Gulf of Mexico while red and orange streams of light flow from the clouds at sunset
An offshore oil and gas platform in the Gulf of Mexico. Credit: BOEM, CC BY-SA 2.0

Typically, the amount of methane released through venting or burned through flaring fluctuates with the amount of oil produced. But this company reported venting the same amount of pollution every day from one platform for nearly two years, regardless of the amount of oil produced. The company also reported some flaring and venting as routine, despite it being more than allowed by regulatory limits and outside of the company’s permits. 

BSEE press secretary Sandy Day told DeSmog, “BSEE has developed and will implement a new training program by April 30, 2023, that will improve BSEE inspectors’ ability to identify violations, as well as suspicious patterns on flare/vent records like those discovered by the OIG.” He added that the training also will better prepare regulators to oversee future flaring and venting requests.

In addition to underreported venting and flaring, Duren and his fellow researchers also observed undetected methane gas leaks in pipelines offshore. In the Gulf of Mexico, regulators require companies to conduct monthly inspections of underwater pipelines via helicopter or boat to look for bubbles on the water surface visible to the naked eye, according to a 2021 U.S. Government Accountability Office (GAO) report. BSEE officials reported to GAO that those inspections, as well as required pipeline pressure sensors, “are not generally reliable indicators of pipeline leakage.” For comparison, regulators in California require companies to perform underwater inspections of active pipelines.

Illustration showing a helicopter flying over a pipeline leaking oil and gas at the bottom of the ocean. Text overlay: 'Currents can diffuse oil and gas leaks, as well as move them far from their source, making them difficult to identify.'
A graphic from a 2021 federal report that flagged problems with current methods of identifying offshore pipeline leaks. Credit: Government Accountability Office

Curbing methane emissions from the fossil fuel industry is one of the most cost-effective ways to reduce greenhouse gas emissions, according to the United Nations Global Methane Assessment. But implementing measures to control methane pollution from the fossil fuel industry has proven difficult in the U.S. And in the Gulf of Mexico, regulatory gaps have had deadly consequences.

Leaking Methane, Crashing Helicopters

In 2014, federal officials warned BSEE that vented methane gas had been sucked into the engines of helicopters landing on and departing from offshore platforms, causing the engines to fail and the helicopters to fall out of the sky. A review of incidents found that helicopters had likely plunged into the Gulf every 1.5 years between 1992 and 2014 because of off-gas, according to a 2015 report commissioned by BSEE.

On the heels of this warning, BSEE sought regulatory input to prevent future helicopter crashes from methane gas and considered requiring methane gas detectors to give pilots a warning when gas was present on or near helidecks. But the agency’s efforts ultimately stalled in 2017 after the fossil fuel industry pushed back.

Crew sits inside a red and white helicopter still on the ground
In 2016, the Bureau of Safety and Environmental Enforcement stated that “mounting evidence suggests exposure to low levels of methane and other combustible gases can be catastrophic for helicopters traveling to and from offshore platforms.” Credit: BSEE, public domain

In a letter to the federal agency, industry lobbying groups — including the American Petroleum Institute and the National Ocean Industries Association — wrote, “The ability to detect methane would not mitigate the consequences of potential methane intake. Rather, operational discipline, adequate training, and effective communication protocols between facilities and helicopter pilots are critical to maintaining safe operations.”

BSEE press secretary Day did not answer questions about what the agency has done to prevent future helicopter crashes caused by methane venting, though the agency has previously said that the problem can be “extremely dangerous” and impacts offshore workers and the agency’s own personnel.

The UK implemented its own regulations after a helicopter carrying 16 people was damaged after a “heavy landing” on a platform in the North Sea in 1995. While no one was hurt, the incident spurred the UK to require air modeling of platforms to ensure that helipads are not in the path of methane emissions. On older platforms where methane could impact helicopter operations, a visual warning system is required that flashes red when methane pollution is above a dangerous concentration level, according to UK standards

“It’s basically like saying American lives are not as important as British or Norwegian lives.”

Megan Milliken Biven, True Transition

“These companies can follow the rules where the rules exist,” said Megan Milliken Biven, the founder of True Transition, a public policy collaborative that advocates for fossil fuel workers. “It’s basically like saying American lives are not as important as British or Norwegian lives.”

Last year, several helicopters traveling to and from oil platforms crashed in the Gulf, including two in December that appear similar to earlier crashes caused by methane gas. Like previous crashes caused by methane venting, the helicopters were just above a platform before they dropped out of the sky. The National Transportation Safety Board (NTSB) has not identified the causes of the crashes. No federal agency currently oversees the safety of helicopters traveling to and from oil platforms, and workers who die in helicopter crashes are not counted in offshore incident statistics. For this reason, it’s not clear if methane gas has caused any recent helicopter crashes.

NTSB spokesperson Peter Knudson told DeSmog, “Regarding the Rotorcraft crashes in December, those investigations are still ongoing and no determination has yet been made about cause or factors.”

Industry’s Leaky Logic

Fossil fuel companies have justified drilling for oil and gas in the Gulf of Mexico by claiming that it emits fewer greenhouse gasses than drilling anywhere else in the world, in part because of offshore restrictions on venting and flaring methane.

“Beyond the obvious national security and energy accessibility and affordability benefits, oil production in the U.S. Gulf has among the lowest greenhouse gas emissions intensity in the world, with approximately half the carbon intensity of other producing regions while also outperforming the rest of the world in methane emissions,” the Gulf Energy Alliance, an offshore industry trade group, wrote in October to federal officials writing the next 5-year offshore leasing plan.

The Inflation Reduction Act (IRA) included $850 million for the Environmental Protection Agency to fund methane reduction measures from oil and gas facilities. Justin Williams, the Vice President of Communications for the National Ocean Industries Association, said he is not aware of any offshore energy companies pursuing government funding to address methane emissions reductions.

“Methane emissions are tightly controlled for offshore operations and are very low when compared to other producing regions,” Williams said. “Well before the enactment of the IRA, the offshore sector has been a leader in deploying technologies for reducing emissions.”

However, as Duren and his colleagues found in their study last year, more and more research is showing that offshore methane emissions are underreported, especially in shallow waters of the Gulf. This pokes a hole in the industry’s argument that offshore drilling has the lowest greenhouse gas emissions intensity in the world, said Chris Eaton, a senior attorney with Earthjustice, which has brought legal challenges against drilling in federal waters.

“What we do know is that there is a hell of a lot more methane being released from offshore drilling than what was publicly known before,” he said. 

The Department of Interior, which BSEE falls under, should crack down on methane emissions offshore, Eaton said. 

“No one really knows how bad of a problem it is and something needs to be done,” he said. “Getting some methane regulations on the books is crucial and it should be done soon.”

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