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. Well the usual posters (investors?) are here again claiming there’s nothing to see, as usual. Why are they always on here then? Keith Taylor is right though to say it’s a larger earthquake than the ones Caudrilla caused when they Fracked Preese Hall-1. Earthquakes in Surrey are almost unheard of and this one is 3 kms from the Horse Hill drill site. Yes it could be purely coincidental but what is there to fear from an investigation into local faulting? The smaller earthquakes in Lancashire resulted in a moratorium. If the drill site is connected by a fault to the earthquake epicentre we need to know, and if the extensive acidisation of 2016 caused this movement now the consequences will be widespread. There is more at stake here than sparing the blushes of a few AIM investors.

    • Wrong direction!
      A self regulation matter?
      Ahhhh, no sweat Sherwulfe!
      We are safe in our democracy when such expertise and sense of direction displays itself so happily!

  2. hewes62-as UKOG, and partners, have yet to restart work at HH then surely checking well integrity will feature as standard practice before they commence any new work-with or without a minor earthquake?
    Meanwhile, I suspect they will be more interested in logging any attempts to create hysteria ahead of, and for reference in the injunction decision. I recall the Greens outside HH last time round with their anti fracking posters. Scientific accuracy seems to be outside of their capabilities-together with attempts to explain the rest of their policies when it comes to election times. Perhaps the money we will save on these MEPs could be diverted to the education budget?

  3. “Miss Scott added she feared it may “be associated” with previous fracking (none took place) at the Horse Hill site a mile away after reading about similar impacts fracking has had in the USA but admitted that “seems a bit far fetched”. Surrey News 2nd April, Luke Jarmyn.

    Hmm. Miss Scott appears to have either been persuaded to modify her views or there is some variation within the reporting. Interesting, but standard.

  4. Indonesia pipeline fire. Possible cause a boat anchor or rust. North Sea pipeline to land shut down due to cracks. Doesn’t take much to cause a disaster does it. So if seismic activity occurs in an area where companies are due to operate or are operating it would be wise to keep checking and even better not put that risk there in the first place

    • Paula
      I will have a look to see why anchor drag got their pipeline.
      Here in the UK ( cardboard regulatory standards some say ), the pipelines are buried ( trenched then backfilled ).

      They are then regularly surveyed, and if uncovered ( by tidal action ) one has to go out with a ship and cover them up again ( called rock dumping ). The rocks are then a haven for fish and lobsters it seems.

      In addition their location is well mapped, and ships in the UK have to know where they are.

      However, if we did away with those pipelines, we would only have whatever we produce onshore UK, so while it would be a fracking company dream for the main pipelines from Norway and the Netherlands to be shut, and result in the cessation of 90% of oil and 100% gas production from uk offshore, it may have to wait awhile.

      Re not taking much to have a catastrophic event, well,it normally does, which is why they are uncommon. But they do happen. Perrow ….Normal Accidents … remains a good read even though written many years ago

  5. Well Paula, that’s your water supplies down the plug hole then. And, shame about those tens of thousands of oil/gas jobs in Scotland.

    Obviously you prefer a good old fashioned maritime disaster-even though the increased risks of that happening were only outlined this week.

  6. I know Sherwulfe. According to Mr. Skinner it is due to events over the horizon, so should all be tickety boo.

    And then after nationalisation we can revert to a far worse leakage situation but will be able to take our baths in a mixture of sea water and sewage. Oh joy, the good old days! (Except this time they will have allocated us all water meters to make sure we pay extra for less.)

  7. If the Epicentre is where it is estimated to be (could be several kilometers out) and at the estimated depth (it may be as deep as 8km or as shallow as 3km), we may be talking about seismic activity in the Collendean fault (or directly below it) – a fault through which UKOG intend to drill this year.

    There is something odd about this. The Horse Hill geology is claimed to be a lookalike for the Broadford Bridge geology. Approximately WNW of both sites there has been seismic activity: at HH 4km away on April 1st; at BB 6km away in 2005. At both there are deep faults running E – W just to the north of the wellpads. The well bores are aimed at and through these faults. At BB1 and 1z, washouts occurred at or near the fault system.

    Washouts are often caused by seismic stress. The flow test at HH ran out of time. The BB flow test ran over considerably due to integrity issues.

    I am not convinced that the semi-conventional techniques used at these sites are suitable for this challenging geology.

    I certainly wouldn’t be comfortable knowing that sites in the area were re-injecting produced water into older wells which cut through active fault systems

    Also, is a recently active fault more likely to allow movement of hydrocarbons from the deeper sources? If so, does that indicate that our famous low sulphur, mobile light oil may well have come from deeper than the Kimmeridge Shale in which it sits?

    • The worm forgives
      Hi, are you sure that a washout ( enlargement of the Borehole ) is often caused by seismic stress?

      Typically a washout is caused by
      1. Hydraulic Erosion
      2. Mechanical Anrasion caused by the drillstring
      3. Inherently sloughing Shale

      In softer or well fractured rock would stress ( both horizontal and vertical components ) be more likely to result in hole closure, not washout?

  8. You will find lots of info on the borehole problems caused by fault stresses in this publication. You will note the line of stress-induced problems across the UK from the Weald through Lancs up to the Shetlands in the second map:

    Understanding tectonic stress in the oil patch:
    The World Stress Map Project by
    MARK TINGAY, BIRGIT MÜLLER, and JOHN REINECKER, Heidelberg Academy of Sciences, Karlsruhe, Germany OLIVER HEIDBACH, FRIEDEMANN WENZEL, and PHILLIP FLECKENSTEIN, University of Karlsruhe, Germany

    • TWF
      Thanks. I am au fait with the use of Borehole breakout information to determine the direction and magnitude of stress. Indeed, in the coal industry we became acutely aware that horizontal stress was an issue, in many cases over and above the vertical stress, something not intuitive at first. It became far more important as we moved to roof bolting as a means of roof support.

      The pictures in the paper Borehole breakout and drilling induced fracture analysis from image logs show pictures familiar to drillers, but also show the limited loss due to this fracture mechanism. My thought was that washouts will have a stress component, and the less competent the rock, the more susceptible to hole enlargement, but that the main causes were as per the list above.

      I must revisit the Kent coalfield information. They took out a few good square miles of coal, dropped the landscape and worked under and through faults with gay abandon. If anything would shake up the region it would be that.

  9. OK so essentially we have two events, conventional drilling and seismic activity. They were not coterminous in time. They were not coterminous in space. There have been over 200 conventional drilling sites in the UK which were presumably drilled at some time in the past. Is there any evidence of a correlation in the UK between conventional drilling and recorded seismic acIivity. I don’t think so.

    • Shalewatcher, do you really think the Kimmeridge is a conventional target? I’ll give you the benefit of the doubt and offer you this highly informative film where you will learn how to tell unconventional from conventional.
      We heard all the same denials after the Preese Hall-1 shocks but the fracking induced earthquakes there crushed the steel drill pipe and the well had to be abandoned. Presumably the acid stimulation carried out at 3 depths at Horse Hill in 2016 was supposed to be at sub fracture pressures but confidence in these operators is understandably low.

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