Horse Hill

PEDL 137
Operator: Horse Hill Developments Ltd; UK Oil and Gas plc (UKOG) has a controlling 85% interest

Massive expansion permitted; campaigners preparing for legal challenge: Horse Hill is in Green Belt countryside west of Horley and north of Gatwick Airport.

Esso drilled just to the north of the current site in the 1980s. They are now believed to have drilled on the wrong side of a fault, and oil companies remained interested in potential oil finds at this site.

In 2012, Magellan was granted planning permission for the construction of an exploratory wellsite including one well (named HH-1). However they did not proceed and instead formed a partnership with Horse Hill Development Ltd.

The well HH-1 was drilled in October 2014 and flow tested in 2016. UKOG claimed to have flowed more than 1500 barrels per day from the Upper and Lower Kimmeridge limestone layers and the Portland sandstone. (The Kimmeridge shale formations are an unconventional target, which require techniques such as acidisation to exploit them.)

In November 2017, HHDL received planning permission to drill a sidetrack (horizontal) well (called HH-1z) and a second vertical well (HH-2) and for flow testing. The sidetrack is being drilled at the time of writing.

Massive expansion on the cards

In December 2018, HHDL submitted a planning application for four more oil wells, plus one wastewater reinjection well, and 20 years of full oil production. This was granted in September 2019. Read a summary of UKOG’s plans on the Drill or Drop website.

If this goes ahead, Horse Hill will be the UK’s second biggest onshore oil production site, after Wytch Farm in Dorset.

Legal challenge

Sarah Finch, a Redhill resident, is preparing to apply for a Judicial Review of Surrey County Council’s decision to allow this massive expansion. Backed by the Weald Action Group and a team of expert environmental lawyers, she is claiming that the Council acted unlawfully on five grounds, covering climate change, earthquake risk and Green Belt. ADD LINK TO PAGE ON THE JR


The plans to drill at Horse Hill have met with opposition at every stage.
The Norwood Hill Residents’ Association, which represents households living immediately around the drill site, has opposed the planning applications and engaged with the oil companies and the Environment Agency over their concerns.

Other local residents, and people involved in the campaigns against drilling at other nearby sites including Balcombe, Brockham and Leith Hill, have organised public meetings and leafleting drives to inform residents about the plans, and held demonstrations at the site.

A protection camp monitors activity at the site and raises awareness of the drilling.


The Horse Hill site is located near the epicentre of the swarm of earthquakes that started in April 2018, and are unprecedented in Surrey.

There is controversy about whether the earthquakes are caused by the drilling. A workshop convened by the Oil and Gas Authority in October 2018 to investigate the cause of the earthquakes concluded there was no causal link between oil drilling and seismic events. However, this was not a unanimous conclusion – and it was only reached as the workshop disregarded the existence of the Horse Hill well site altogether, as they believed there was no activity there at the time of the first quake. This was later established to be false.

An independent assessment by geologists at Edinburgh University reached the opposite conclusion. Their report, ‘Further Potential for Earthquakes from Oil Exploration in the Weald’, published in February 2019, said: “Our assessment supports the concern that Horse Hill oil exploration triggered the earthquakes. We infer that future oil exploration and production close to critically stressed faults in the Weald is likely to result in similar earthquake events.”

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