Summary of our “Fracking by stealth” peer reviewed paper

This is a summary of our recent research article Acid stimulation: Fracking by stealth continues despite the moratorium in England, published in the international peer-reviewed journal Energy Policy earlier this year (see press release). The article is a fuller, updated policy discussion of our previous briefing paper on acidisation.

  • Nearly two years after the introduction of the fracking moratorium (2 Nov 2019), at a time when the UK is trying to demonstrate climate action leadership by hosting COP26, the threat of “small-scale fracks” and fracking-like acidisation still hangs over multiple communities across the country.
  • This is because the moratorium only covers very high volume fracking as defined by the Infrastructure Act 2015 (IA2015), leaving out entire gamut of lower volume fracking operations.
  • Our recently published paper describes the source of this flawed definition and how it trickles down through the oil and gas regulatory framework, denying vital protections to the environment and surrounding communities.
  • We follow the evolution of this definition in legislation, namely the substitution of “each stage” with “any stage” (with relation to the 1000 cubic meters of fluid volume threshold) first in 2016 for ‘protected areas’ and then in 2017 for all hydraulic fracturing operations. This small change of a single word tightened the definition significantly, indicating the government’s own realisation that the IA2015 definition was not adequate.
  • Even after the amendment, the definition remains deficient. We demonstrate this by looking at the history of the three shale wells fracked in the UK to date, all of which triggered notable seismic events (Preese Hall-1 in 2011, PNR-1 in 2018 and PNR-2 in 2019) – none of them would have met the original definition and only Presse Hall-1 met the tightened definition.
  • In addition, the amended definition is far from capturing acid stimulation – the fracking-like method of unconventional hydrocarbons extraction that involves many of the same risks and concerns surrounding hydraulic fracturing, namely: induced seismicity, air and noise pollution, groundwater contamination and industrialisation of the countryside.
  • We clarify the distinction between conventional and unconventional rock layers and explain the key concept of permeability. A low permeability (by consensus defined as less than 0.1 millidarcies) implies that the resource is unconventional, meaning that it requires special methods to extract the resource. Above that value, conventional methods suffice.
  • Further, we point out that the Environment Agency regulates acid-based injections on the basis of operator “intent”, often exempting them from any further reporting or monitoring of these activities. Acid stimulation is also exempt from the Traffic Light System (TLS) monitoring of induced seismicity. 
  • We also describe the inconsistencies between the four oil and gas regulatory regimes (Oil & Gas Authority, Health & Safety Executive, Environment Agency and the planning regime) – they all use different definitions of hydraulic fracturing.
  • Due to the changes to legislation and confusing regulatory landscape, the 2019 moratorium is also ambiguous as to which operations fall under its scope. Confusing statements have been made by politicians and Ministers, including Andrea Leadsom in her written statement on 4 Nov 2019 announcing the moratorium. We discuss these ambiguities and confused, inaccurate messaging.
  • Finally, we propose a new definition of unconventional hydrocarbon exploitation that could be adopted across the regulatory regime. This definition would:
    1. More adequately capture the current unconventional oil and gas exploration and production which the operators pursue under the guise of conventional activities,
    2. Help to streamline the regulations and
    3. Finally allow the affected communities to call the threats by their name. Fracking is a highly emotive word for a reason; the industry knows it well and it is in their interest to play down what they’re doing with confused language.
  • Most crucially, if our definition were to be adopted, it would stop most, if not all, new onshore oil and gas developments because conventional deposits have already been discovered and many of them depleted. 
  • Our proposed definition of fracking (in relation to treatments aimed at increasing hydrocarbon extraction) is:

All well stimulation treatments of oil and gas wells which increase the permeability of the target rock volume to higher than 0.1 millidarcies beyond a 1 m radius from the borehole.

1st Anniversary of the Fracking Moratorium

We take another look at the fracking moratorium in England ahead of its 1st anniversary on 2 November. Much of this update is based on reporting by Drill Or, publisher of independent, evidence-based journalism about the onshore oil and gas business in the UK and the campaign against it.

Picture credit: John Houston

In our last update we shared Mr Kwasi Kwarteng’s response to our letter asking the Government to replace the current moratorium on high volume hydraulic fracturing with a ban on all fracking, that is all well stimulation for oil and gas exploration and production. We made this request when the moratorium was announced last year because we are concerned that, although these stimulation techniques involve similar risks to those posed by high volume hydraulic fracturing, they are currently exempt from many of the legal and regulatory constraints. Furthermore, the climate change implications are equally as problematic for all forms of well stimulation. (See more here).

Mr Kwarteng’s response was a polite but firm refusal and a dismissal of our concerns, but he maintains his assurances that fracking is “extremely unlikely” to happen in England (see also here and here).

It is ironic then that on the same day the above assurance was last made, Egdon Resources confirmed that it would use a “small-scale hydraulic fracturing activity” to stimulate oil flow at Wressle in Linconshire. Also recently, UKOG said they considered using stimulation to fix the ongoing water issue at Horse Hill, located in an earthquake zone near Gatwick, although they did not clarify what type of stimulation (and previously ruled out matrix acidisation). None of these methods are covered by “fracking” as referred to by Mr Kwarteng. Neither is exploratory drilling into unconventional rocks, including for shale gas; for example, IGas just said it intends to ask for an extension of its planning permission at the shale gas site at Misson Springs in north Nottinghamshire.

Several other existing or proposed sites in the Weald Basin and across the country are at risk of acid washing and squeeze. Acid wash is meant to be a well maintenance technique, but the Environment Agency, which regulates this area, has failed to clarify the boundaries between well maintenance and the fracking-like acid stimulation, and as it stands, permits and exclusions are granted based on the oil and gas firms’ stated intent…

Why moratorium and not a ban?

Mr Kwarteng says that the Government’s position on the moratorium won’t change unless the science shows that it can be done safely and with minimal disturbance. Other voices argue that the moratorium is more likely to be reversed by politics than science and Cuadrilla’s owner, AJ Lucas, expects it to be lifted, but not before the end of 2020… Aurora Energy dropped its application to frack at Altcar Moss in west Lancashire, but vowed to challenge the moratorium. Third Energy, which intended to frack at Kirby Misperton in North Yorkshire, is trying to extend the life of its Ryedale gas wells despite an order from the Oil & Gas authority to plug and abandon them, raising suspicions they might be biding time until the moratorium is lifted.

The moratorium has always been criticised as electioneering ahead of the December 2019 UK general election and, in our view, the recent developments don’t offer a great deal of confidence that it is truly permanent. Some well-known researchers and campaigners pointed to a link between Brexit and investment in fracking, suggesting that the climate for fracking might become more positive in post-Brexit Britain, negotiating its trade deals alone. Possibly without any deal with the EU, the UK will be more keen to strike a deal with the US, where, no matter the outcome of the presidential election, fracking is not going away.

New Research

New peer-reviewed research by emeritus Professor David Smythe, focused on the regulation of unconventional oil and gas exploitation, shows us, through 14 case histories from around the UK, “a laissez-faire and frequently incompetent regulatory regime, devised for the pre-unconventional era, and which has no geological oversight or insight”. 

Another paper, focused on air pollution, environmental justice and shale gas exploration in England, concluded that the UK Government and its advisers “marginalised, downplayed or ignored” public health concerns, that regulations lagged behind the science and that the industry was able to influence decision-making. We now also know that, in just one week in January 2019, the fracking operations at Preston New Road caused an unintended release of planet-heating methane equivalent to the environmental cost of 142 transatlantic flights.

This research highlight, yet again, the need for an expanded ban for all well stimulation treatments for oil and gas exploration and production.

Meanwhile, a new in-depth report by the Weald Action Group, the SE England campaign network group, shows why we don’t need more onshore oil in the UK, regardless of how it is extracted.

Update on our open letter to the Government calling for a ban on all forms of fracking

We would like to thank all signatories to our open letter that asked the Government to replace the current moratorium on high volume hydraulic fracturing with a ban on all well stimulation for oil and gas exploration and production.

We are sharing with you the response we received on behalf of the Government from the energy minister, Kwasi Kwarteng.

Mr Kwarteng’s letter doesn’t respond to the issues carefully detailed in our letter to him. The documents cited within his response have been referenced in our in-depth legal brief that was attached in our letter. This brief is based on months of research into the regulatory framework, co-authored and signed off by leading environmental firm, Harrison Grant.

The response is a polite but firm refusal and a dismissal of our concerns. Specifically on acidisation, it is true that the Environment Agency regulates this area, but the EA has failed to clarify the boundaries between well maintenance techniques and acid stimulation – a fracking-like technique. As it stands, permits and exclusions are granted based on the oil and gas firms’ stated intent, which results in insufficient restrictions, reporting and monitoring to guard against acid stimulation taking place under the guise of well maintenance. The EA’s regulatory position remains opaque, with no clarity whatsoever over where the boundary between unacceptably dangerous acid stimulation and routine well maintenance lies.

Confusion also remains with respect to which operations require hydraulic fracture plans, while the ministerial statement on the moratorium on fracking referred to by Mr Kwarteng refers to hydraulic fracture plans as well as to hydraulic fracture consents – two different regulatory consents that apply to operations of different scope. This highlights the many inconsistencies in the legal and regulatory framework for hydraulic fracturing and the need for an expanded ban for all well stimulation treatments.

We also believe that investment in the post-covid recovery should be in line with climate change targets and therefore on green energy, not domestic oil and gas, involving acid stimulation or otherwise. Given the drop in demand, it would be an easy win for the Government to look proactive on climate change by switching their focus to renewables.




Open letter to the Government asks for a ban on all forms of fracking

BROCKHAM, SURREY, 2 November 2019 – The Government’s announcement today to end its support for fracking is welcome news, but the moratorium covers only high volume hydraulic fracturing as defined by the Infrastructure Act 2015. It does not cover other forms of stimulation of oil and gas wells, including acid stimulation.

This is despite studies conducted abroad suggesting that many of the risks and concerns surrounding hydraulic fracturing are the same as for acid stimulation, namely induced seismicity, air and noise pollution and groundwater contamination. This has not been well studied or publicised in the UK, despite a number of communities across the country potentially affected.

So today we are launching a legal briefing that sets out the loopholes and ambiguities that exist in the legal and regulatory position surrounding the use of acid stimulation in England. The briefing is titled Acid Stimulation: Fracking by Stealth (available on request) and co-authored by Brockham Oil Watch and Harrison Grant Solicitors, with scientific Advice from David K. Smythe, Emeritus Professor of Geophysics, University of Glasgow.

We are also launching an open letter to the Government based on the recommendations of the legal briefing. We are asking for 1) an amendment of the definition of fracking in the Infrastructure Act 2015 to include all well stimulation treatments which may enhance the productivity of oil and gas wells by increasing the permeability of the target rock, and 2) a permanent ban on all well stimulation for oil and gas exploration and production. We are inviting signatures from campaign groups, environmental groups, elected representatives in the affected communities, academics, NGOs and other supportive individuals and groups.

One specific recommendation of our briefing is that the traffic light monitoring system to monitor and manage induced seismicity should apply to all well stimulation treatments, not only high volume hydraulic fracturing. This is further supported by the fact that the Preston New Road (PNR) tremors, which have brought about today’s moratorium, were caused by injections of fluid well below the volumes defined in the Infrastructure Act 2015 definition [1,2].

The largest tremor at PNR was 2.9ML whilst the largest tremor registered in Newdigate, Surrey was 3.1ML. Suspicions that the Newdigate tremors are caused by operations at the nearby Horse Hill site could be better understood with the implementation of a well-designed traffic light system and adequate reporting requirements.



Editor’s Notes

Open letter to the Government: Stimulation of oil and gas wells – reforms required is available at and legal briefing: Acid Stimulation: Fracking by Stealth is available on request.

About Brockham Oil Watch:    Brockham Oil Watch (BOW) is a non-political group of local residents concerned about the threat of unconventional hydrocarbon extraction from the Kimmeridge Clay Formation (or other unconventional reservoirs) at Brockham, and gaps in the current legislative/regulatory framework. For more information visit

About Harrison Grant Solicitors:    Harrison Grant provides experience and expertise in public law, planning and environmental law (including international law), human rights and advice on governance for charities and campaign groups. Noted for its role in high profile cases, it is recognised as a leading law firm of leading lawyers. For more information visit

About Professor Smythe: David K. Smythe is Emeritus Professor of Geophysics at the University of Glasgow. He took early retirement from the Chair of Geophysics in 1998 when the Department of Geology & Applied Geology was closed. He lives in France. His main current research interests are fracking, nuclear waste disposal, and nuclear accidents. For more information visit: 

The Newdigate Earthquake Swarm:   As of 2nd November 2019, 57 earthquakes have been registered in Newdigate. The strongest tremor measuring 3.1 ML was recorded on 27th February 2019.



Traffic Light System Or No System At All ?

This blog is based on our submission to the All PARTY PARLIAMENTARY GROUP ON THE IMPACT OF SHALE GAS – TRAFFIC LIGHT SYSTEM, held on 2 April 2019.

Our submission focused on the fact that there is no TLS in the Weald basin because the regulatory regime doesn’t view the operations taking place here as fracking. Fluid injections under pressure up to fracture pressure are allowed at Horse Hill and elsewhere in the Weald (and beyond), but there is no monitoring or reporting of injected fluid volumes, injection pressures or even dates of these operations!

Acid-based stimulations already are or will be a relevant concern at sites across the South East of England (mainly in Surrey and West Sussex plus Isle of Wight) as well as places such as Wressle in Lincolnshire, Ellesmere Port in Cheshire and West Newton in East Yorkshire.

Acid stimulations involve pressurised injection of fluids underground, including acid in various concentrations, at below hydraulic fracture pressure (matrix acidisation) or above (acid fracturing). These types of stimulations, along with high volume hydraulic fracturing, should be seen as forms of fracking. Indeed, in California, where there is a history of extraction using the various methods, fracking bill SB4 (2013-14) regulates hydraulic fracturing and acid stimulation treatments at any applied pressure in exactly the same way. In Florida, a heated debate is taking place right now about the proposed bills banning hydraulic fracturing, some including matrix acidisation and some leaving it out.

Acidisation - Smythe

Source: David Smythe

In the UK, the regulations of acid stimulations are virtually non-existent. This includes induced seismicity regulations. The Traffic Light System only applies where a Hydraulic Fracture Plan is required, although it seems not in all cases, as the Oil and Gas Authority retains discretion over the details required in an HFP. It is not clear either for which operations an HFP is required, but in any case, an HFP would never be required for operations intended at below hydraulic fracture pressure. (See below note: When is Hydraulic Fracture Plan Required?)

Operations proposed in the South-East are never described (by the operators) to the regulatory agencies as any kind of fracturing. In fact, they are not described as stimulation at all, but rather as acid wash, arguably exploiting the loophole in the system created by the lack of a clear definition of what is acid wash and what is acid stimulation. The permitting of these procedures lies with the Environment Agency, which is the only regulatory body in the UK to even make a reference (although in very vague terms) to acid stimulation. By calling their intended operations acid wash the operators are also able to escape environmental regulations though de minimis exclusions.

Despite the procedures being described as acid wash, the pressure at which they are allowed by the EA to be performed is anywhere up to hydraulic fracture pressure.[1] [2] And for these types of operations, an HFP is never required, nor is the reporting of dates/timings of treatment, volume of injected fluid or pressure at which it was injected. Environmental permits for the so-called acid washes are issued based on “operator intent” and there is very little monitoring of what actually takes place once the permit is issued. Monitoring is limited to visual observations of equipment on surface during occasional site visits (for example we were told by the EA on 4 Feb 2019 that heir most recent routine site inspection of Horse Hill occurred on 23 August 2018), which might include on site document check, for example of waste records.

This is a stark contrast with the type of monitoring and reporting required for high volume hydraulic fracturing operations, which includes daily reporting of injection summaries and charts, such as the example here.


Hydrochloric acid at Horse Hill – photo taken in July 2018

HCl at HH 21.1.19.jpg

Hydrochloric Acid with Additives – photo by Horse Hill Monitoring Post taken on 21 Jan 2019

According to analysis by David Smythe, Emeritus Professor of Geophysics in the University of Glasgow, the Horse Hill-1 well was drilled into a fault zone.  And the assessment of Professor Stuart Haszeldine, Dr Cavanagh and Dr Gilfillan at the University of Edinburgh supports the concern that oil exploration at Horse Hill triggered the recent swarms of earthquakes around Newdigate, possibly also by bleeding the well annulus to manage pressure prior to testing. Therefore, it could be inferred that anything that has the potential to change the downhole pressure, either to increase it or to decrease it, could induce seismicity. And if that is correct, then even activities such as an acid wash under a pressure slightly greater than formation pressure could be responsible for earthquakes. And even more so if the acid is applied at a greater pressure, approaching hydraulic fracture pressure.  Moreover, there is no monitoring in place to ensure that the injection pressure never exceeds fracture pressure. This is left to the operators themselves to monitor.

In addition, the Cuadrilla data on fracking at Preston New Road (example in Appendix 2) confirms that on several occasions the company put some (1 or 1.5 cu m) of 15% Hydrochloric acid into the well, presumably at the start of the frack.  So they have been, at least partially, acid fracking already.  This should also be a strong indicator that the Traffic Light System should apply to acidisation and acid fracking as well.

We therefore propose that the Traffic Light System (along with all the required reporting and monitoring) should be extended to include all pressurised injections at any applied pressure, and that it should be considered whether other operations that have the potential to induce seismicity should also be included.


When is a Hydraulic Fracture Plan Required? 

The Oil and Gas Authority’s Consolidated Onshore Guidance (Dec 2017) says that HFP is required when hydraulic fracturing is proposed as part of completion. It also says: If the proposed injection volumes fall below the BEIS associated hydraulic fracturing thresholds, the OGA may decide less information or monitoring is appropriate, but an HFP will always still be required. This implies that an HFP is always required for operations which exceed hydraulic fracture pressure.

However, in May 2018, as part of oral evidence given to Communities and Local Government Committee regarding planning guidance on fracking, Tom Wheeler, Director of Regulation at the OGA, seemed to have contradicted this guidance suggesting that HFP is always required only when the operations meet definitions set out in legislation[3]: “We use the Infrastructure Act definition as clarified by the Secretary of State last year to determine when a company needs to submit what we call a hydraulic fracture plan.  If a plan does not meet the water-based tests that are set out in the legislation, we would not always require one.  We reserve the right in guidance to require one should we think there are risks of seismic activity as a result of it.  We would always require a hydraulic fracture plan when it meets the tests set out in the Infrastructure Act.  We find the definition useful and we rely on it for that purpose.”

[1] “The activities outlined in the Waste Management Plan and any of the application supporting documents does not include proposals for well stimulation techniques above the fracture pressure of the surrounding target formations.” P.36

[2] See here, pink highlight

[3] Q123: