Oil company says “We’re not to blame for Surrey earthquake” – but local concerns remain

180401 seismic chart BGS

British Geological Survey charts on the Surrey earthquake

The oil exploration company, UKOG, says there’s no connection between its drilling site at Horse Hill near Gatwick Airport and the Easter earthquake in Surrey.

The 2.7 magnitude earthquake on 1 April was centred on the area around Newdigate, west of Horley, and felt by people living near Horse Hill.

It was seven years to the day after an earthquake in Lancashire, which was later linked to fracking by Cuadrilla.

But UKOG, the leading investor in the Horse Hill site, told DrillOrDrop this afternoon that there was no link between oil exploration and the earthquake. In a statement, the company said:

“We strongly refute the far-fetched, unscientific and malicious connection made between Horse Hill and the earthquake in Surrey on April 1st.

“There is no drilling, testing or underground works taking place at Horse Hill or at any of our sites at present. All such work at Horse Hill ceased over two years ago.”


Horse Hill oil exploration site in 2016. Photo: Horse Hill Developments Ltd

Keith Taylor, the Green Party MEP for south east England, called this morning for a suspension of oil exploration in the area pending an official investigation. He said:

“There is an understandable concern. We need the Department for Business, Energy and Industrial Strategy and the Environment Agency to hold an urgent investigation to see what they can find.

“This is an area of the Weald that the industry has its sights on turning into an oil field. There are operations at Horse Hill, Brockham and Leith Hill and they’re within a stone’s throw [of the earthquake epicentre].

“Being a member of the European Parliament, we work on something called the precautionary principle where if there’s a demonstrable risk we ought to suspend operations in Surrey until reports from the Department of Business, Energy and Industrial Strategy and the Environment Agency have clarified the situation.”

Oil exploration across the Weald in southern England has attracted criticism for the use of acid in wellbores. Companies have argued that it is a standard oil industry technique to clean the wellbore and stimulate the flow of oil from surrounding rocks. But opponents have said it is the equivalent of “fracking under the radar”.

The site operator at Horse Hill has planning permission to use acidising in operations to test the flow of the well.

Lisa Scott, a resident living near the Horse Hill site, who felt the earthquake, supported Mr Taylor’s call for a suspension of operations. She said she was worried about possible damage to the wellbore at the site. The series of earthquakes linked to fracking by Cuadrilla near Blackpool deformed the Preese Hall well.

Ms Scott said “based on figures given in the current planning application, during the flow testing in 2016 the acid used would have travelled 12m into the formation”.

She said:

“That sounds questionable to me. I want categoric proof that there’s no risk to our homes. A lot of us have huge mortgages that we’re paying on our homes to allow us to live in this area.”

She told DrillOrDrop:

“I would like to know who would pay for damage caused to our homes if this happens and it is confirmed to be associated with the acidization of wells that is happening in this part of the country.

“I’m really worried that the government is trying to push through changes to planning guidance, which would require councils to plan positively for oil and gas drilling, when we really don’t have the geological knowledge to fully understand the risks.

“I really think there is a huge potential risk to thousands of homes in our area if well drilling and acidisation is done to the extent that the oil companies are telling their investors they intend to do, which is drilling wells back-to-back across our countryside.”

DrillOrDrop asked UKOG whether there would be any check for damage to the Horse Hill wellbore. We’ll update this report with any response from the company.

180401 seismic data BGS

The British Geological Survey (BGS) told us it was well-known that induced earthquakes could be caused by activities including hydrocarbon exploration and production, waste disposal, mining and geothermal power generation.

Brian Baptie, a seismologist with the BGS, said:

“In the case of the magnitude 2.7 ML near Newdigate, Surrey, on 1 April, we are unable to say if this event was caused by hydrocarbon exploration or production mainly because of the uncertainties in our estimates of the earthquake epicentre and depth. We used a process a bit like triangulation to locate earthquakes and our closest monitoring station was over 70 km away, so the errors in our location estimate are several kilometres.

“I believe there is no current drilling or testing at the Horse Hill 1 site. The LR/24- 4 well was drilled in 2014 and well testing was carried out in 2016. Similarly, I believe that all oil production at the Brockham field, just south of Dorking has been conventional and there has been no hydraulic fracturing or “fracking”. We have not recorded any seismicity associated with this field in the past.

“Background levels of earthquake activity in this part of England are very low and I believe that this is the first earthquake that we have recorded in Surrey since BGS started instrumental monitoring in the 1970s.”

DrillOrDrop asked the Department of Business, Energy and Industrial Strategy and the Environment Agency whether they would investigate the earthquake.

A spokesperson for BEIS said:

“There are no current operations ongoing at the Horse Hill or Leith Hill in Surrey. As noted by British Geological Survey, there is no evidence to show a link between any oil or gas operations in the south of England and the earthquake recorded on 1st April 2018.”

  • Keith Taylor is visiting anti-drilling campaigners outside the Horse Hill wellsite tomorrow.

79 replies »

  1. Shalewatcher-it is important to remember the “fear of the unknown” is the antis mantra, even when it is “known”, and then it can always be “modified” ie. “fracking” at HH. Snowflakes are a useful audience.

    When a lady living 1 mile from HH is energised at the beginning of this month to be fearful, having researched fracking in USA, you have to ask the question-why did she not research what had actually gone on at HH? Must have all been pretty inconspicuous and normal not to bother to do so. Just like the well drilled next to an ex works colleague garden (we used to meet in his house for regular business meetings). I discussed with him the local impact, and he was totally relaxed about it. Some noise at night whilst drilling took place, but in his words, no more conspicuous than the farmers grain driers in the autumn, a few lights at night during the drilling process but his curtains were the solution. Once in operation, a few lorries in and out but no more so than from the local neighbourhood properties receiving oil deliveries for their domestic use, and/or having their septic tanks emptied.

    How times have changed with the “benefits” of the Internet. Progress?

  2. Earthquakes can ccur wherever built up seismic pressure successfully finds a way to escape. Deep drilled gas wells, whether recent or not, create this opportunity. As do volcano vent holes. Fracking violently shakes the substrate, causes pressure to build and migrate, seriously exacerbating this situation.
    Swarms of earthquakes then occur wherever large numbers of unconventional high pressure hydraulic fracturing shale gas wells are drilled and fracked. Only big numbers can be justified to make initial investments worthwhile so test fracking results bear no relationship to mass production fracking consequences regarding air and water pollution, vehicle movements, earthquakes, toxic waste disposal etc.
    Cuadrilla boast of turning the Fylde Peninsula into the largest Gasfield in Europe, thousands of wells being drilled and fracked over the next decade or two. This will destroy the integrity of the area as is clearly demonstrated in The List of the Harmed, evidence from the mature fracking locations in North America.


    Banned elsewhere for causing air and water pollution plus causing swarms of earthquakes, why would anyone think Fracking is a good idea, except those attempting to make money from the Ponzi scheme?
    Also the burning of fossil fuels is proven to cause environmental disaster, renewable energy projects are definitely the best way to satisfy our energy needs and are obviously being created all around us! You know that makes sense.

  3. Still confused with oil drilling and fracking Peter? No. you are not but require the spread of fake news to make someone excited.

    Dirty game, but someone has to do it. However, those crying wolf when there is none, will lose their sheep when there is one. Credibility, once lost will not be easily replaced.

    • As you say Martin, I’m not at all confused. Not about this or many other things.
      I am however very confused as to why fracking failures Cuadrilla were again given the opportunity to frack the Fylde after their previous efforts were stopped following drilling problems causing local earthquakes/tremors.
      The resulting contaminated waters and fluids, millions of litres by the way. were dumped some 30 miles away in the Manchester Ship Canal as no other options were pre-arranged! This sounds familiar as Cuadrilla are now attempting to vary planning regulations to permit waste fluid dumping in the nearby brook which empties into the Irish Sea. So the Blue Flag bathing waters of St. Annes and Blackpool are at risk as are the famous Lytham shrimps and other seafood!
      Which idiot still thinks or ever thought this was a good idea?

      • Peter
        The frack waste into the ship canal was a permitted discharge, post treatment, though not now allowed, so not likely to be repeated. I see the term dumped is regularly in use. Has someone proof it was emptied directly into the canal?

        Re waste fluid into the nearby brook, is that frack fluid, or the runoff from the pad?

        I doubt it’s frack fluid, but some readers here may be under the impression that it is, rather than just water from the pad. Can you clarify the issue?

  4. It wern’t us, we don’t frack there anymore, we never felt it anyway, it’s all a figment of your imaginations (mass hysteria like!!!), seismic activity is “normal”, it was only a little one, nobody got hurt, leave us alone this is bullying, so and so gave us permission and said we can do it, we only did it for a short time, we’ll put everything back the way we found it….honest, stop picking on us, fracking is just like bitcoin… nobody really trusts it but some people are making loads of money at other people’s expense.

    • Do they have permission for reinjection Lisa? Investors, do you guys know? Reinjection is known to be connected with induced seismicity.

      If nothing else they may be dangerously close to an active fault. Echo’s of the Preese Hall-1 debacle here.

      Funny how they make out it’s a good thing if the tight Kimmeridge formation is naturally fractured (that’s FAULTED to the rest of us) then wonder why stimulation and reinjection cause earthquakes. Are these activities properly insured?
      I hope due dillegence has been done on scrutinising their financial resilience in case of disaster!

      • My understanding is that produced water from both Brockham and Lindsey were both reinjected to Brockham. If this is different geology, it appears to be in contradiction to EA guidelines.

  5. Now 5th July 2018, we’ve just had the SEVENTH of the swarm of earthquakes in Surrey this year, the THIRD in the last two weeks.

    Still not the fault of fracking?

    • Robert
      No fracking in the weald yet. So it’s difficult to link something that has not taken place to the earthquakes.
      Or it’s just a wind up!

      • Do you think it’s a good idea to stimulate during an extended flow test on or near an active fault, or to drill new wells and a side track on or near an active fault? Virtually no earthquakes within the Weald for 500 years then 7 with 4.5 kms of HH 1. This is the BGS info.
        I’m not asking a rhetorical question, please tell me if you think we have enough data now to say this is safe.

          • Dorkinian
            I note that the well will be acidised, but this is done so below fracture pressure ie, no fracking.

            The length of the well test is immaterial if it is successful. It will become a producing well.

            So I am still with BIES on this one.

            • when a liquid (i.e. the acid) turns to a gas (i.e. when the acid dissolves the rock to become CO2 + metal salt) it increases in volume 32 times at the same pressure. If the volume cannot increase (i.e. it is within a rock formation), the pressure must increase. And what about the nitrogen that is reported to also be uses?

            • Lisa3

              The acid and its products are not trapped in the rock when produced, they are at whatever pressure the fluids surrounding them are at.

              The nitrogen was used for Nitrogen lift. You inject the nitrogen in at the bottom of the well and it bubbles up, lifting the oil with it. The pressure required to get it to the bottom of the well is whatever the pressure is at the bottom plus anything needed to overcome friction.

              An alternative to nitrogen is(hydrocarbon ) gas lift (if you have spare gas ). Some offshore platforms import gas from other platforms to carry out gas lift.

              If the pressure at the bottom of the well was high, you would not need help to lift it!


      • Flow testing commenced on the 27th June as announced by UK Oil and Gas Investments PLC to London Stock Exchange. The next day there was an earthquake.

        • David

          Flow testing, being the flowing of oil from the well did not start on 27th June. See later DOD post re these earthquakes and the comments by BGS and OGA.

          Or the UKOG announcement which notes that after set up of the equipment they have to remove three temporary suspension plugs prior to testing the Portland.

          What else was going on down there? Any piling on building sites ( bored or piled ), use of explosives in quarries or drilling for water?

          It will be interesting to know exactly when oil flowed, or will flow.

  6. Dorkian
    I think that flow testing an existing well ( I did not see that they were stimulating it in any aggressive way ) would trouble the weald.
    As noted in the report above the drilling and well testing was done a while ago.
    Plus the epicentre is deep compared to the oil and gas activity.
    It is worth reading the paper linked to by P Tresco in recent posts to see how past drilling activity and extraction has not caused seismic activity ( unlike the fracking in the Fylde). Unfortunately it is $39 to read it.

    The BGS data is recent, so it would be difficult to,say that there has been no activity in the last 500 years. The BGS website says that there has been seismic activity within the last 500 years ( see DOD post July 5th ), rather than virtually no earthquakes.

    So, overall, in my opinions n, it is likely to be a co incidence. But good that the BGS are installing additional monitoring equipment and thatvtheir opinion is on their website.

    I have experienced the Ollerton Quakes and was not troubled by them, so I may be more relaxed about these events… others may not be.

    • I would suggest that to flow test a low permeability formation like the Kimmeridge the stimulation will be aggressive (remember it is shale and micrite, both unconventional reservoirs) and they are planning more drilling (from memory a side track and 2 more wells).

      The extended flow test is 150 days, that’s a huge test period.

      The depth is simply a nominal value of up to 5000m as the nearest monitoring station was over 90 km away hence the lack of precision as to the epicentre(s).

      The “evidence for historical earthquakes in the last 500 years” well, actually, they might have said “in the last 1000 years” is one quake at Dorking in 1551 (467 years ago, and that’s it (Lewes is not in the Weald). This means they are EXTREMELY rare – until 1 April this year, that is.

      So UKOG are using unknown forms of stimulation (I won’t speculate but you know the source rock) for an extended period in a quake zone where there is inadequate data on the faults and on the epicentric positions of the 7 earthquakes to date. They acknowledge that are not experts in this field as they repeatedly tell us they are conventional drillers.

      hewes62, I hope you enjoyed the 2-0 against Sweden and that you are not hoping to find work in the oil industry down here in the Weald, I think our calls for a moratorium are sound here.

      • Dorkinian
        Re work, no, the money is abroad or offshore related, plus at 63 retirement is fine, especially at this time of year.

        It is worth keeping an eye on what goes on. The plans are ( it seems ) to let the well flow with some conventional ( ie not out of the ordinary ) well stimulation techniques. However should these not work and it is true that the shale and micrite need hydraulic fracturing ( as per past discussions on DOD ) to make the play viable then it will be a different ball game,

        • Thanks hewes62 that was my understanding of the situation. Depends how much they want to get out of the ground, a bit or as much as possible.

  7. I am guided by David Hume’s ‘An Enquiry concerning Human Understanding. published in 1748: “In our reasoning concerning matter of fact, there are all imaginable degrees of assurance, from the highest certainty to the lowest species of mora evidence. A wise man, therefore, proportions his belief to the evidence.”

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