The Environment Agency is seeking public comments on its proposal to allow Angus Energy to dispose of waste water underground at the Brockham oil site in Surrey.
Despite local concerns, the EA said it was minded to permit water reinjection at Brockham.
In a draft decision document, the EA said it was satisfied that risks had been identified and that operating procedures were “sufficient to mitigate the risk to groundwater”. There was no need for groundwater monitoring, it said.
Waste water, also known as produced or formation water, often comes to the surface during oil and gas extraction.
It is usually very salty and may be radioactive. Companies seek to reinject it back underground to avoid expensive water treatment and to support the pressure in the hydrocarbon reservoir, improving hydrocarbon flows.
Angus Energy has previously said it would give up the Brockham site if it could not reinject waste water.
The EA refused a reinjection request for Brockham in November 2019, saying there was a “lack of suitable information” in Angus Energy’s hydrogeological risk assessment. The EA also had concerns about the integrity of the BRX3 borehole where the water would be injected.
The new application, made in March 2021, sought permission to reinject waste water from the Portland sand and Kimmeridge clay formations. The water would be disposed of into the Portland sand layers.
The waste would come from Brockham and other fields, particularly Angus Energy’s Lidsey oil site in West Sussex, the EA said.
In considering the new permit application, the EA twice asked for more information.
Local people remain concerned that water reinjection at Brockham could pollute groundwater.
But in its draft decision document, the EA said:
“There is a negligible risk of pollution to groundwater from the reinjection of produced water into the Portland sandstone formation”.
The EA also said the reinjection of produced water into geological formations from which hydrocarbons had been extracted was the best environmental option to “minimise the exposure of the public to ionising radiation from the disposal of radioactive waste”.
Brockham Parish Council, local councillors and campaign groups said they were also concerned about Angus Energy’s operational record at Brockham.
The EA said it acknowledged “historic issues in respect to operator competence”.
But it said “there is no known reason to consider the applicant [Angus Energy] will not comply with the permit conditions” or not be “financially able” to comply.
There were additional concerns that water reinjection could cause earthquakes. The site is 7km from the area around Newdigate in Surrey, which saw a swarm of earthquakes in 2018.
The Environment Agency said it had not asked for additional seismic data from Angus Energy and it was satisfied with the information it had. Seismicity linked to oil and gas operations was the remit of the Oil & Gas Authority, it said.
Angus Energy would be allowed to reinject a maximum of 24m3 of produced water per seven-hour day, the EA said. This was a “minor volume” of produced water, it said.
The injection rate would be a maximum of 1.3 litres/second. Pressure would be below that needed to fracture the formation, the EA said, and company procedures would ensure there was no over-pressurisation of the reservoir.
Angus Energy has permission to handle radioactive material from Brockham. But the new permit would not allow it to receive radioactive waste water from Lidsey or other sites.
Surrey County Council has confirmed that Angus Energy also does not have planning permission to accept waste from other sites.
The company is currently applying for planning permission to produce oil for 15 years from the BRX4 well at Brockham.