Dorset oil site continues to vent hundreds of tonnes of methane

Hundreds of tonnes of climate-warming methane is being released into the atmosphere by the UK’s longest continuously producing onshore oil well, despite curbs ordered by the environmental regulator.

Methane venting at Kimmeridge oil site, Dorset, recorded by Clean Air Task Force, October 2021 using an FLIR GF320 camera, the industry standard for identifying emissions at oil and gas sites

The Kimmeridge site in Dorset, operated by Perenco, has legally emitted methane directly into the atmosphere since oil production began in the 1980s.

In early 2019, the Environment Agency (EA) instructed the operator to produce plans to use the waste gas, which is extracted along with the oil, rather than vent it.

The EA set a deadline of November 2019 for the plans. But venting was allowed to continue at Kimmeridge and the EA has now revealed the practice is unlikely to stop until the end of summer 2022.

Methane is one of the most powerful greenhouse gases, particularly in the short-term. It accounts for about a third of global warming since pre-industrial times and levels in the atmosphere are rising faster than ever.

Methane’s ability to trap heat over 20 years is at least 86 times greater than carbon dioxide (CO2). Over 100 years, methane’s global warming potential falls to 28-36 greater than CO2.

At the COP26 climate talks in Glasgow last year, 105 countries signed the Global Methane Pledge, agreeing to cut methane emissions by 30% by the end of the decade, compared with 2020 levels. They agreed that the greatest potential for methane cuts was in the oil and gas sectors.

Also last year, the International Energy Agency said cuts to methane emissions and oil and gas sites were vital to limiting global warming to 1.5C.

Official data

Official data from the Oil & Gas Authority has recorded venting from onshore wells in the UK since October 2016. In that time alone, the data shows the Kimmeridge site released 3,014 tonnes of gas.

In the 12 months to September 2021 (the most recent figure available), the well vented 599 tonnes of gas. During the same period, the well produce 2,864 tonnes of oil.

Perenco has reported that about half the Kimmeridge gas is methane and half non-methane volatile organic compounds.

This indicates that about 300 tonnes of methane were released each year, the equivalent of more than 25,000 tonnes of CO2 (20 year global warming potential). The average carbon footprint for a person in the UK is 10 tonnes of CO2e per year.

If Kimmeridge continues to produce oil and gas at a similar rate, another 150 tonnes of methane will be emitted in the next six months, before venting stops.


In 2018, DrillOrDrop worked with local researcher Stuart Lane to investigate methane emissions at the Kimmeridge site. At the time, the EA told us “all methane is released through the permitted release point”.

But it said the site’s environmental permit was being reviewed and Perenco would be required to produce a plan on how it would use or dispose of unwanted gas.

According to official data, production at Kimmeridge stopped briefly that year and for two months there was no venting.

More than three years later, we reported on research by the Clean Air Task Force which found “significant methane emissions” at Kimmeridge. The gas was still being released through vents in two oil storage tanks about 5m above the ground.

Changes planned at Kimmeridge

In November 2021, the EA revealed that the aim was to stop the emissions, known in the industry as cold venting, by the end of summer 2022.

The information came in response to a Freedom of Information request by Stuart Lane.

The EA said Perenco had bought a road tanker to transport liquified gas off the site. But it said:

“There have been delays in procuring and fabricating part of the specialised equipment, which is being sourced from an Italian manufacturer. Once the equipment has arrived in the UK, we will ensure that it is installed and commissioned in a timely manner, to reduce emissions from the Kimmeridge well site.”

“Well should have been suspended”

Stuart Lane said:

“One might expect for this well to remain inactive until the issues, identified by the EA, had been resolved and for a permit to be withheld pending resolution.

“This, however, is not what followed. Perenco was allowed to restart production and three years on, all methane and non-menthane volatile organic compounds are still being vented to the atmosphere.

“Whilst it is good that the EA has seen reason to tighten controls on this well, it is worrying that the regulatory framework has not required operators to stop pumping until standards are met. Clearly, it has been deemed more reasonable to release potent greenhouse gases unabated for an additional three years whilst the operator brings standards in line with EA requirements.

“For Perenco, releasing methane to the atmosphere is almost certainly much cheaper than capturing it in this location. The longer Perenco can get away with doing so, the more profitable. If the EA don’t stop them or require speedy resolution, why should they care?”

Vicki Elcoate, of the Weald Action Group, which has been helping uncover methane emissions at sites across the South of England said:

“Reducing methane is critical to slowing climate change.  At COP26 the UK committed to a significant cut in highly polluting methane emissions by 2030.

“Any preventable emissions which are subject to regulation should be at the top of the list to achieve this goal and the Kimmeridge is a good example of that – there should be no further delay in stopping this pollution”.

Deadlines and enforcement

DrillOrDrop put a series of questions to the EA on the regulation of the Kimmeridge site.

An EA spokesperson told us:

“The Kimmeridge site, amongst other onshore oil and gas facilities, has been permitted to cold-vent gas since production started in the 1980s.

“A revised permit included an improvement condition which the operator is working on implementing – we will not hesitate to take enforcement action if agreed improvements are not made.”

The EA confirmed Perenco had submitted its gas management plan for Kimmeridge by the deadline of November 2019. The proposals were approved in September 2020.

But supply chain problems meant the original commissioning date for new equipment, in August 2021, was not met.

The spokesperson said:

“We have to apply our regulatory powers in a fair and consistent way in accordance with the Regulator’s code.

“We have taken steps to ensure that the equipment is installed by the operator as quickly and safely as possible, and will not hesitate to take enforcement action if the current commissioning date is not going to be met.

“Our regulatory focus on reducing methane emissions from the onshore oil and gas sector support the government’s commitment to the Global Methane Pledge, in line with our statutory powers.”

13 replies »

  1. “The EA said Perenco had bought a road tanker to transport liquified gas off the site.”

    I would be interested to know how they liquify the natural gas on such a small scale and transport it – it need to be cooled and moved at between -145 to -163 degC.

    Perhaps it is compressed rather than liquified?

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