Regulation

Guest post: Mind your fracking language

pnr 190828 Ros Wills

Fracking equipment at Cuadrilla’s shale gas site at Preston New Road, 28 August 2019. Photo: Ros Wills

As the dust settles on the government’s fracking U-turn, former ministerial adviser professor Peter Styles explains why definitions matter and how one part of England could be excluded from the moratorium.


peter styles 2

Peter Styles

It is perhaps important before even considering the issue of “fracking” and its different manifestations to understand the difference between conventional hydrocarbon reservoirs and unconventional ones.

Simplistically, oil and gas are formed by the effect of pressure and temperature on biological materials deposited within sediments hundreds of millions of years ago.

Much of that escapes or migrates (i.e. moves out of the source) and is gone and we never see it again. Some is retained within the rocks where it was formed. And some migrates and is trapped in a different rock formation, which has a cap rock sealing it in and geometry which prevents it moving further or at least slows it down. This requires rocks to have porosity (spaces where oil and gas can be stored) and permeability, the requirement for pores to be connected so that oil and gas (and water) can flow, albeit slowly.

Strangely, it is this third scenario which we call conventional oil and gas and a great deal of technology, seismic, drilling and other, has developed in order to identify, characterise and exploit this kind of hydrocarbon reservoir all over the world.

The second case, where the hydrocarbons stay where they are formed, usually because there is little or no permeability to permit flow, is what we call unconventional oil and gas despite this being probably the largest part by far of the world’s hydrocarbon reserves.

If we can increase the permeability by some method, we can get this oil and gas out and how we do that depends on the nature of the rock. If, as is common, the rocks are shales, fine grained sediments, then this is usually done by hydraulic stimulation or fracking.

This is done by injecting high-pressure water with a limited number of chemicals so that new fractures and pathways form and these are kept open by injecting a proppant, either sand or a synthetic material. In the USA, huge quantities of oil and gas have been liberated by this method in the relatively geologically undeformed basins of the central USA.

If the rock is strongly cemented, so that the pores are blocked by calcite (calcium carbonate) or silica, or is itself a limestone, then the permeability can be increased somewhat by dissolving these cements or matrices with acids (hydrochloric for calcite, or hydrofluoric for silica). This is known as acidising or acid stimulation.

It is also possible to combine these two stimulation techniques by injecting the acidic solution at a high enough pressure to fracture the rock as well. This is known as acid fracking.

pnr 190823 Maxine Gill 10

Cuadrilla’s Preston New Road fracking site, 23 August 2019. Photo: Maxine Gill

The UK has lots of hydrocarbon-bearing shales, mainly in Lancashire and Yorkshire/Nottinghamshire, albeit in geological conditions which are much more complex than the USA case because of the geological history of Western Europe.

It appeared very tempting, to companies and UK government alike, that this could be a new source of domestically-sourced gas.

Hydraulic stimulation (fracking), sensu-stricto, has been attempted in Lancashire by Cuadrilla at two sites (Preese Hall and Preston New Road) from the carboniferous Bowland Shales.

But the phenomenon of induced seismicity, where the fracking process stimulates movements of pre-existing faults, resulted in a 2.9ML seismic event (amongst many others of lower magnitude and despite numerical modelling predicting that 2ML was likely to be the largest induced event).

This led to the Oil & Gas Authority (OGA) reporting to government that current technologies cannot either predict or mitigate this level (or higher) of seismicity.

I was part of the commission which recommended to government that a Traffic Light System based on event magnitude should be put in place so that fracking should stop for analysis and re-evaluation when a threshold (0.5ML) was exceeded.

The Government has now announced a moratorium on this mode of fracking using high-volumes of fluid (1,000 m3 per stage or 10,000 m3 in total) for the foreseeable future.

191026 HH Well site DoD

Horse Hill well site, 26 October 2019. Photo: DrillOrDrop

The other, up to now rather less noticed, UK onshore oil and gas exploration is in the leafy landscapes of the Weald, south-west of London, particularly around Horse Hill and Brockham in Surrey and also in Sussex, in younger Jurassic rocks: the Portland Sandstone and Kimmeridge Limestone amongst others.

Here the jury is out as to whether acid fracking, (the more aggressive combined acid and hydraulic stimulation process) is also actually banned under the recently-announced moratorium, as it generally uses lower volumes than the 1,000/10,000 limits).

There is additional concern because a sequence of earthquakes up to magnitude 3.1 ML have occurred around Newdigate in Surrey, just south of Brockham and very close to Horse Hill over the last year.

Although the British Geological Survey (BGS) and some university researchers appear to have ruled out a link to a recommencement of activity at Brockham or activity at Horse Hill, the existence of this seismicity does indicate that there are faults which could potentially be further destabilised by hydrocarbon-related activities.

There is, to say the least, considerable local concern and calls for the moratorium to be clarified/extended to categorically encompass acid-fracking processes.

  • Professor Peter Styles is emeritus professor in applied and environmental geophysics at University of Keele. He is a former President of the Geological Society of London, a project leader with the ReFine fracking research project and previous Head of Geology at Keele University. He advised the former prime minister, David Cameron, on fracking-induced seismicity.

13 replies »

  1. Thank you drill or drop for a very interesting & mostly informative article by Peter Styles.

    My only disappointment was two areas which imo. I thought he could have developed a little further to enhance the article.

    These two areas were:

    1. The natural fracturing of the Weald & what that means for the processes discussed or if they will be needed.

    2. The second is the oil production & processes that have been successfully used in the South East of England at Whych Farm since 1973 without incident.

    I understand that Whych Farm at it’s peak produced around 112,000 BOPD & has not been detrimental to the area, property values the landscape or the surrounding beaches.

    I am unfortunately unable to hazard a realistic guess as the the economic or employment benifits that Whych farm has brought to the area or the national economy.

    I understand that the South East was only part of another article & would certainly be interested in seeing these areas developed.

    I am personally glad that there has been a moratorium on fracking as I believe that the Hydrolic fracturing & simultaneous & sismic events are inexorably linked.

    The earthquakes at Newgate imo. opinion have nothing to do with the conventional oil & gas programs in the Weald & there are may more frequent & stronger earthquakes in the UK where there is not even oil & gas exploration or production.

  2. Fracking is not on any agenda for UKOG. Normal oil production from limestone which is naturally fractured involves injection of water only to replace oil as it comes to the surface. It might be better to have geologists more familiar with petrochemical processes to comment, otherwise the uninformed will again draw the wrong conclusions as evidenced by commentary ” the existence of this seismicity does indicate that there are faults which could potentially be further destabilised by hydrocarbon-related activities.” Of course, limestone is naturally “faulted” and the existence of seismicity extends across the whole of the UK to the tune of several thousands. There is simply no comparison with high pressure fracking with acid and other liquids and normal petrochemical recovery undertaken at Wytch Farm and on the Weald..

  3. Thank you for this very interesting post Prof Styles.
    My layman understanding of the conventional reservoir is that the oil/gas migrate out of shale rock into a more porous rock formations like sandstone and trapped and accumulated there like an air pocket until it is tapped out by drilling into that accumulation.
    For this to happen in large conventional reservoir the oil/gas must also be able to flow relatively freely through the shale rock and migrate out of its shale rock source into the conventional reservoir accumulation, indicating these shale source are porous enough (probably very high quartz and silicas content shale formation??) for the oil/gas to flow out of shale rock in large quantities.
    In the case of Bowland shale reservoir, Cuadrilla already stated they are brittle and has high quartz content. The conventional gas accumulated in sandstone formation under Morecombe Bay is said to come from Bowland shale source. This suggests to me that gas can flow and migrate relatively free ly through Bowland shale formation. Another evidence is that gas did migrate out of Bowland shale upward and accumulated in the rock formations under Elswick site which is close to PNR site.
    To my mind Bowland shale may act more like a conventional reservoirs and may not need high volume fracturing as in the case of US basin where shale rock grains are more compact and a bit tighter. Cuadrilla may just need conventional well stimulation to get the gas flow into its well.

    • The above link shows UK earthquakes in the last 50 days.

      The South East is an area where the have been very few of this naturally occurring fanominum..

      I live in Shropshire where there is no oil & gas exploration or production & there have been 3 earthquakes in the last 50 days of 1.4 / 1.6 / 2.4 magnitude they are fairly common & hardly make the news.

      • MH
        You might find this useful –

        https://www.merriam-webster.com/dictionary/phenomenon

        “phenomenon – noun

        phe·​nom·​e·​non | \ fi-ˈnä-mə-ˌnän , -nən\
        plural phenomena\ fi-​ˈnä-​mə-​nə , -​ˌnä \ or phenomenons
        Definition of phenomenon
        1 plural phenomena : an observable fact or event
        2 plural phenomena
        a : an object or aspect known through the senses rather than by thought or intuition
        b : a temporal or spatiotemporal object of sensory experience as distinguished from a noumenon
        c : a fact or event of scientific interest susceptible to scientific description and explanation
        3a : a rare or significant fact or event
        b plural phenomenons : an exceptional, unusual, or abnormal person, thing, or occurrence”

        If your spell checker has the incorrect spelling of the word (phenomenon) as a real word it may be substituted as a phonetic spelling if you have a phonetic dictionary, as in many schools. You can reset that by changing the spell checker in settings to a USA English dictionary and then back to a United Kindom dictionary and the phonetic spelling will be replaced with the English spelling.

        https://www.merriam-webster.com/dictionary/phonetic

        “phonetic – adjective

        pho·​net·​ic | \ fə-ˈne-tik \
        Definition of phonetic
        1 : representing the sounds and other phenomena of speech: such as
        a : constituting an alteration of ordinary spelling that better represents the spoken language, that employs only characters of the regular alphabet, and that is used in a context of conventional spelling
        b : representing speech sounds by means of symbols that have one value only
        c : employing for speech sounds more than the minimum number of symbols necessary to represent the significant differences in a speaker’s speech
        2a : of or relating to spoken language or speech sounds
        b : of or relating to the science of phonetics”

        Hope that helps. I am sure no one wants to think that a repeated misspelling of (phenomenon) is any sort of act of provocation or ridicule of DrillorDrop and the readers. As i am sure you will not want that either.

        Regarding the recent swarm of earthquake phenomenon in the the south east relative to the admitted oil and gas exploration causes in the north of England. The timing appears to be significant. In spite of the BGS and certain University reports that earthquakes are not related to the present oil exploration and extraction techniques used by those companies in the south east. There is maybe a significant factor of timing that draws the coincidence that earthquakes in that area have been unknown for 40 years or more prior to the recent operations, but have occurred only since those operations began. How or why that coincidence has occurred may be just coincidence or significant for other reasons. At present there is no actual evidence either way other than the BGS and University reports which may be subject to further study as more is known.

        There is also a significant revelation that the BGS is under Non Disclosure Agreements with the oil exploration companies. The BGS are subject to censorship and deletion of data if the companies refuse to allow such data to be published and can demand that data is deleted that may point to the cause being from the present oil exploration and production activities or not. If that was a factor in the BGS conclusion, then we may never know if it has been expunged from the record.

        See this DrillorDrop article on that subject

        https://drillordrop.com/2019/08/24/suspicion-over-fracking-firms-secret-deal-with-geological-agency/

        How all that and many other aspects of the present Moratorium plays out post election is any ones guess.

  4. Once again drilldroop peddling its negative slant on the UK oil and gas industry’s attempts to make our country less dependent on oil imports from all the other dodgy oil producing country’s.
    Give it a rest Ruth you’re becoming boring and annoying probably related to Nicola Sturgeon….similar one sided vision.

  5. An interesting and to my knowledge, entirely factual post. In my increasingly lengthy experience, Drill or Drop consistently and independently posts factual articles, with scrupulously accurate quotes from both sides of the debate (except when one side of the debate refuses to comment). Please don’t give it a rest Ruth or Paul, because I don’t know any other source that is so trustworthy or comprehensive in its coverage. If you’re bored John, go away and find a more interesting hobby. Perhaps read a dictionary to improve your offensive spelling.
    On another issue, our govt could put more political will and funding into developing the whole gamut of renewable energy, which is there for the taking, but requires improved technology and investment. This would make our country less dependent on oil and gas imports, while reducing carbon emissions, vastly improving air quality and providing employment. Who knows, perhaps even 64,000 jobs!!

    • Surely Mike you are not suggesting that renewable energy needs more of the sort of funding that it has enjoyed-like £150k net profit per turbine whether producing electricity, or not-to make it attractive? Is that what you mean by “there for the taking”?

      “Our govt.” has no money, other than tax payers money or borrowing, which tax payers have to repay.

      Alternatively, the energy providers could fund some more, by subsidising of renewable energy?

      Oh, they just go bust having to do what they do currently!

      • By ‘there for the taking’ I meant that the energy is already there and freely available in the form or solar, wind, geothermal, water and wave etc. It just needs the technology and infrastructure to exploit it. But of course you knew that really Martin. The problem is that small household or purely local energy generation systems could significantly reduce the profitability of current energy suppliers, and more importantly, fossil fuel suppliers… and their investors… and greatly reduce fuel poverty too. Of course, those investors could invest in something with a vastly more sustainable future and also with a reasonable return. Anyone would think that you don’t approve of replacing fossil fuels with renewables, slowing or reversing AGW and consequently improving our environment and ecosystem dramatically Martin.
        I don’t design the subsidies and support for energy generators/suppliers. Sadly, I have to rely on govts and their civil servants to do that effectively and efficiently. Maybe one day they’ll get it right.
        It’s hardly the right time to claim our govt has no money. All our prospective govts have apparently discovered a vast magic money forest, so we’re all quids in (until at least 18 Dec).

  6. Oh, but I do support renewables-if they can be shown to be economic. My air sourced heat pump is great in that respect.
    ( But try putting 100 into a housing estate and I see problems.) My hybrid was rubbish -so it has gone.

    The magic money forest is simply more tax for the tax payer to pay. And it will not be the rich because they can move their money in a fraction of a second these days.

    In the time for UK to get to net zero I will guarantee our reduction will have been replaced at least 5 fold by others, so there will be NO slowing or reversing. Now, if you could persuade countries to decarbonise fossil fuel and then make good use of the carbon, that could be very different if then supported by fusion energy. A smattering of wind and the rest, and the job is done.

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