Public meeting on earthquakes fills up village hall

Click here to go to David Smythe – Beare Green playlist

Video credit: Phil Jackson, itistv 

Over 150 people, including a number of local councillors, attended a public meeting on earthquakes and unconventional drilling in the Weald Basin held last Saturday (18 May) evening at Beare Green Village Hall. The gathering was organised by Brockham Oil Watch and chaired by Max Rosenberg, Chairman of CPRE Mole Valley.

David K Smythe, Emeritus Professor of Geophysics in the University of Glasgow, delivered the main talk, covering the history of oil & gas exploration in the Weald between 1960-90 versus the current phase led by penny-share companies of questionable competence and integrity, the reasons why he supports the Edinburgh University thesis that the Newdigate earthquakes are induced by activity at the Horse Hill site, and recommendations for local residents as well as their elected representatives.

Professor Smythe criticised the authorities and the operator for withholding crucial work programme logs from the Horse Hill site, and advised that the precautionary principle should apply halting operations while more research is undertaken. He called for residents to collate systematic data on earthquake damage.

Earthquakes meeting- Full room.jpg

Photo credit: John O’Houston

Ada Zaffina of BOW gave a brief overview of the loophole in the UK regulatory system with regards to acid stimulation, potentially allowing these stimulation treatments to take place under the guise of acid wash. The presentations were followed by a lively Q&A time stretching the duration of the meeting to two hours.

We are very pleased with the turnout, especially since we were competing with the Eurovision Final and the FA Cup Final. The level and detail of questions and comments from very astute locals and councillors shows deep concern about the earthquakes and the possibility of larger magnitude tremors. We hope that this will embolden more people to speak up about their concerns and demand clear action.

With the recently released FOI documents showing that a well intervention on HH-1 was planned for early April 2018, UKOG’s fundamental argument that the earthquakes started before they did any work on this well is put into question. There are striking coincidences between the timings of operations (at Horse Hill) over the last year or so and ongoing tremors, and those are much stronger than the 0.5ML that halts operations on fracking sites up North. Many people in Newdigate live in constant anxiety over the prospect of another, possibly stronger earthquake. We shouldn’t be searching for a smoking gun that Horse Hill is inducing the tremors, we should be asking that operations be stopped until we are absolutely sure that they are not causing them.

We would also like to thank everyone involved in the organisation and promotion. This event is a great example of worried communities coming together.


Presentation Slides:

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Smythe surrey earthquakes talk 18may19 v1.1 annotated

Blog Posts

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 seem 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 on 1 July 2018

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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 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:

Update on Air and Water Monitoring

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We are pleased to report that we have received laboratory results of the first air and water samples collected around the Brockham wellsite. The levels of pollutants are in line with what one would expect in a rural location. (Please see below for more details.) The forced break in Angus Energy’s operations earlier this year due to unexpectedly finding water in their new well is allowing us the time to continue sampling and laboratory analysis to establish a robust baseline reflective of seasonal weather changes before any extraction from the unconventional Kimmeridge layers starts. Having good baseline data is necessary to provide a reference point against which to assess the future monitoring of air and water quality after oil production starts.

We are paying for this work with funds raised from the community through crowdfunding, and from grants. Unfortunately, the current regulatory regime doesn’t require any baseline monitoring. There has never been any groundwater testing at Brockham despite the fact that the risky practice of waste water reinjection underground (including from another site in Lidsey) had been allowed for a number of years. This practice was banned at Brockham in November 2018 thanks in part to our efforts and the pressure we were able to put on the Environment Agency through our petition signed by over 27,000 people. In their decision to prohibit reinjection the EA cited concerns over well integrity and Angus Energy’s operating procedures that “are not up to the required standard.” (Please note waste water was reinjected into well BRX3 drilled many years ago. The issue of injecting acid mixed with other chemicals into the new sidetrack BRX4Z remains).

To our knowledge, there has never been any air monitoring around the well either, except for the reporting by the operator of the amount of gas produced annually, which they reported as nil. It is not known whether these reports are based on estimated or actual volumes, and they are not verified by the EA (links here and here).


We commissioned H2Ogeo to provide a baseline water quality report for ground and surface waters in the vicinity of the Brockham Oil Well. A total of five sampling locations were identified consisting of three groundwater wells and two surface water points. A total of nine water samples were collected over two events and sent under appropriate chain of custody to an accredited laboratory for analysis. Quality Control procedures were used with the laboratory to provide assurance that the results were accurate and good quality data was obtained. The field and laboratory results indicated some chemical differences between major ions in surface and groundwater, but they did not identify any hydrocarbons or methane gases above the limits of detection.


We commissioned Gair Consulting to assist with the set-up of six monitoring points on three farms around the wellsite, together including six NO2 and three BTEX (Benzene, Toluene, Ethylbenzene, Xylene) tubes. Those are changed on a regular basis and sent for analysis. We are aiming to collect c. 6 months of baseline data. Results so far are in line with average air quality in a rural location. Slight variations in hydrocarbon levels across locations were detected, but those are likely attributable to the proximity to a road. Production from the Kimmeridge layers has not started yet and so there has not been any flaring at the Brockham wellsite, or any production of gas from these strata.


If you would like to contribute to the cost of collecting baseline data and future monitoring, please donate via the crowdfunder:

FRACKING OR NOT? Oil & Gas Extraction Plans in the Weald Basin – Some Planning Considerations

image (1)

Illustration submitted as part of the planning application for the expansion of the Horse Hill Site

This blog is based on a submission to Surrey County Council regarding application SCC Ref 2018/0152 for the drilling of four more hydrocarbon wells and one reinjection well, site expansion, workover and sidetrack drilling, and production from six wells for 25 years at Horse Hill. For a related post with instructions on how to object see here.



  • The strata targeted by the proposed wells are interbedded micrites (references to the “Kimmeridge Limestones” are misleading) and shales of very low permeability – an unconventional reservoir. Unconventional reservoirs likely require stimulation such as acidisation or hydraulic fracturing to produce commercial quantities of hydrocarbons.
  • Current Surrey Minerals Plan was adopted in 2011, before unconventional hydrocarbon reservoirs were identified in the UK. It lacks specific policies, creating a void in the local planning system.
  • The National Planning Policy Framework’s definition of fracking is broad and includes acid stimulation techniques, which are planned in the Weald according to an industry sponsored paper.  One of the key planning policies developed elsewhere in the country for fracking sites is a min 500m buffer zone. Well density is also a key consideration given the requirement for back-to-back drilling to scale production.
  • There are significant inconsistencies in the definition of fracking across the UK onshore oil and gas regulatory regime. This presents a challenge with respect to monitoring and enforcement of breaches.


Background – The Kimmeridge Clay Formation – Unconventional Target Reservoir

Three out of the four new production wells proposed in this application are targeting the so-called Kimmeridge limestones, which are inter-bedded with shale layers forming the Kimmeridge Clay Formation (KCF) hybrid reservoir. The KCF stretches across the Weald Basin and is currently pursued at various drill sites in Surrey and West Sussex including Brockham, Broadford Bridge, and Balcombe. David Smythe, Emeritus Professor of Geophysics in the University of Glasgow, points out that the so-called limestones of the KCF are very impure and have high content of mudstone (shale) and he concludes that “both the micrites and the shale have extremely low permeability, and will require to be fracked if oil is ever to be exploited commercially from the KCF”.[2] Permeability (the ability to allow fluid to pass through it) is a key measure used to determine whether a reservoir is conventional or unconventional, i.e. requiring stimulation such as acidisation or hydraulic fracturing (fracking) to flow hydrocarbons. The permeability of the Kimmeridge micrites is between 0.02 and 0.032 mD (and that of the shale layers is even lower)[1] – well below the generally accepted boundary of 0.1 mD below which a formation is considered unconventional.

In addition, according to a 2014 study of the Jurassic shales of the Weald Basin by the British Geological Survey and the Oil and Gas Authority (then Department of Climate Change), a close analogue to the KCF is the Bakken Formation of North Dakota[3] – unconventional hybrid reservoir that requires fracking to produce commercial quantities of hydrocarbons.

Even if it is assumed that HHDL will contain their extraction to the so-called limestones (although from an engineering point of view it seems difficult if not impossible to limit extraction to these layers only, if oil is found in a single pool within the fracture network present across at least two so-called limestones separated by shale)[4] which the company says will not require fracking, the micrites are only the first target, the main target being the entire Kimmeridge Clay Formation, as explained by Stephen Sanderson, Executive Chairman of UK Oil & Gas Investments PLC (HHDL’s parent company)[5]. However, once this application is approved, the planning authority is unlikely to be consulted on any changes to the target geological layers as this will be within the remit of the Oil & Gas Authority. Therefore, Surrey County Council (SCC) should consider that this application is for wells that will be used for the extraction of Kimmeridge shale oil from the entire Kimmeridge Clay Formation.


Policy for Shale Oil (Unconventional Oil Resource) and Fracking


Buffer Zones

SCC’s Q&A document Oil and Gas Development in Surrey[7] classifies shale oil as unconventional oil resource which “has to be extracted using a technique known as hydraulic fracturing or, more commonly, as fracking.” The document says that shale oil is likely to be present in Surrey, citing the BGS/OGA study of the Jurassic Shales of the Weald Basin already mentioned above, but that none of the operations – either existing or planned – are for unconventional oil extraction. We propose that this is incorrect; both Horse Hill and Brockham are unconventional oil sites.

The Surrey Minerals Plan Core Strategy 2011[8] doesn’t offer any policies for unconventional reservoirs; it doesn’t even mention the words unconventional or fracturing. Therefore, if SCC recognised that this application is for unconventional shale oil extraction that will require fracking or acidising, it would have to look to the national planning policy, and to other local minerals planning authorities, which started developing policies for fracking sites. In particular, the North Yorkshire Minerals Plan is going to be the first plan in the country that includes policies on fracking. This plan was discussed in April 2018, when a planning inspector provisionally approved proposals for a minimum 500m buffer zone between fracking sites and homes or schools to protect against significant impacts such as noise, light pollution, negative health effects due to flaring for example, visual and other, unknown impacts.[9]

According to the planning statement submitted as part of the Horse Hill application, there are 16 residential properties within 500m radius from the site: Wray’s Farm House, approximately 370m to the east, Five Acres approximately 410m southeast and High Trees Court (14 flats) approximately 350m to the north. The access road is in closer proximity to residential properties with the entrance being located near to Wray’s Farm House. The statement fails to mention the Lomond Equestrian Centre, which borders with the site, and which was significantly affected by flow tests at the Horse Hill site in 2016. Impacts included noise, lighting overnight, smells and health effects. Local press reported that “four people have had nosebleeds, two of whom have never had them before, while two horses in particular are suffering runny noses and eyes.”[10] Clients as well as the business owner expressed concerns and worry.

The residential properties and the equestrian centre are at a high risk of significant negative impacts from this significantly expanded development.

Well Density 

Development of a shale reservoir is different from conventional oil and gas fields, where most of the development takes place up front ahead of any production. In shale, development is incremental, meaning that development and production progress simultaneously throughout the field life. Therefore pad density is another crucial consideration in terms of land use.

UKOG state in their Investor Presentation dated Nov 2018 that they plan 4 to 8 sites per 100km2, which is up to one site every 2 miles. Each pad would have multiple horizontal wells.[11] The company also just announced a new proposed site in Dunsfold, Surrey[12] and it said that it would submit an application to Surrey County Council in spring 2019 to drill, core and test the Godley Bridge Portland gas discovery and the underlying Kimmeridge.[13] Therefore it would seem prudent for the planning authority to have a policy in place to manage long term land use and safeguard against potential significant cumulative effects arising from this incremental industrial development across the county.

“No Fracking” Condition

On the other hand, if SCC maintains that this application is for a conventional development, it might want to offer assurances that there will be no fracking taking place. The definition included in the National Planning Practice Guidance (NPPG) on minerals, paragraph 129 Reference ID: 27-128-20140306 is as follows:

Hydraulic fracturing is the process of opening and/or extending existing narrow fractures or creating new ones (fractures are typically hairline in width) in gas or oil-bearing rock, which allows gas or oil to flow into wellbores to be captured.

This definition covers not only the very high volume hydraulic fracturing, but also acid stimulation treatments such as acid fracturing and matrix acidisation – a process performed below fracturing pressure but which does extend existing fractures (through dissolving them with acid mixed with other chemicals). Acid stimulation is much less recognised and studied than high-volume hydraulic fracturing, but it has recently received increased attention; for example it is currently on route to being banned in the state of Florida, along with other forms of fracking.[14] Acid stimulation uses lower volumes of fluid and lower pumping pressures than high volume fracking, but the number and concentrations of chemical is higher, raising concerns about the toxicity of this process.[15] According to a paper commissioned by UK Oil & Gas Plc and authored by EY, a multinational consultancy, the Kimmeridge so-called limestones, even if naturally fractured, will require the use of acid stimulation.[16]

In the event that SCC approves this application, the planning authority is likely to impose a condition that no fracking as defined in NPPG will be allowed under this planning permission (as it did for the Brockham wellsite). However, it is unclear how the planning authority would determine a breach of such a condition and how it would enforce it.  The other regulators (i.e. the Oil & Gas Authority and the Environment Agency) define fracking in different ways.  The NPPG definition of hydraulic fracturing used by planning authorities is very wide, whereas the volume-based definition in the Infrastructure Act 2015 (and its subsequent regulations) used by the OGA are very narrow.  The Environment Agency has a different approach altogether.  It uses a pragmatic assessment based on the materials, equipment and methods being used to determine whether hydraulic fracturing is taking place. Moreover, there doesn’t seem to be a mechanism anywhere in the current regulatory system for onshore oil and gas, by which it could be verified whether fracking operations that do not qualify under the volume-based definitions are actually taking place.[17]


[1] Nutech Executive Report Summary, BROCKHAM #1, September 2016,

[2] Smythe, D.K., Objection to amendment of planning permission to drill at Broadford Bridge, West Sussex, Aug 2017,

[3] British Geological Survey & Department of Energy & Climate Change, The Jurassic shales of the Weald Basin, 2014,

[4] UKOG, January 2019 and

[5] Master Investor, Sanderson S, Shale: A New World Oil Order? February 2016,

[7] Surrey County Council, Oil and gas development in Surrey Q&A Nov 2017,

[8] Surrey County Council,

[9] Drill Or Drop? Live news updates: Inspector backs buffer zones between N Yorks shale gas sites and homes plus local fracking definition, April 2018,

[10] SurreyLive, Staff and animals at Horse Hill equestrian centre ‘feeling unsafe’ as drilling debate rages, March 2016,

[11] UKOG, Horse Hill and Beyond,

[12] Drill Or Drop, Oil company reveals plans for new Surrey well site, 15 February 2019,

[13] UKOG, 2019-2020 Strategy and Drilling Plans,

[14] Miami herald, Two fracking ban bills passed today, but critics say one isn’t green enough. 13 February 2019,

[15] Abdullah, Khadeeja, Acidizing Oil Wells, a Sister-Technology to Hydraulic Fracturing: Risks, Chemicals, and Regulations, UCLA, 2016,

[16] EY, Kimmeridge Limestone Oil: The UK Opportunity, April 2016,

[17] Drill Or Drop? Campaigners call for tougher rules on acid use at Weald oil sites, November 2018,