Shale gas myths and reality – part 1

With European energy security draining away, any discussion about our energy future should begin with energy security, price and a rounded assessment of the impact that new energy supplies may have upon our environment. European primary energy production peaked at 1136 million tonnes oil equivalent (mmtoe) in 1997 and has since fallen 15% to 970 mmtoe in 2012[1]. It is against this backdrop that many European governments are now embracing The American Dream in promoting shale gas as the cheap, clean, abundant and secure “bridging fuel” to a carbon free energy future. None of this is true.

Shale gas is not cheap, it’s certainly not clean and in geological terms it is a low-grade resource. Any country going down this route is also making a commitment to drill hundreds to thousands of new wells every year to keep the gas flowing. So where does the truth really lie? In part 1 of 2, I describe what shale gas is and consider environmental factors such as intensity of development, potential contamination of ground water and CO2 emissions. Part 2 will consider economics and shale gas potential of the UK.

Figure 1 The Northwest corner of Bradford County in Pennsylvania USA [2]. This is a production sweet spot in the prolific Marcellus Shale. Mixed arable land with forest close to the Appalachian Mountains, not too dissimilar to parts of rural England and Europe. How many shale gas drilling pads and production wells can you see in the image? What impact does this have on a landscape already overprinted by Man’s roads, farms, towns and quarries? Click on all images to get a large version that opens in a new browser window.

The energy debate

With energy prices rising once again and frost creeping under the doors of many pensioner’s homes in Scotland, politicians are blaming everyone but themselves for our energy plight. In trying to reach any sensible conclusion in a discussion about our energy future, it is important to understand our energy past. Since the middle of the 19th century growing supplies of cheap fossil fuels (first coal, then coal+oil and then coal+oil+natural gas) powered industrial society enabling the global population to explode to 7 billion souls (Figure 2). This era is coming to an end. Not because of climate change but because we are running scarce of cheap fossil fuel. Hence the great interest in the alternative to cheap fossil fuel i.e. expensive fossil fuel, i.e. shale oil and gas. Cheap fossil fuels brought society a myriad of benefits that we have all come to take for granted (Figure 2). Society is going to have to accept that any effort to replace cheap fossil fuels with alternatives, be it wind power, nuclear power or expensive fossil fuels means there are going to be costs associated with those benefits. These costs come in the way of higher energy bills, inconvenience and environmental degradation. The choice is between accepting these costs and having the lights on at Christmas or not. The energy debate is multi-dimensional, and so there is no right answer. Only a choice between a number of poor options.

Figure 2 In the 18th century, Europeans were running out of wood to burn. And then along came coal, the steam engine and before we knew it, Porsches, iPhones and holidays in Spain. The wealth created by consuming fossil fuels has underpinned the explosion of global population by providing food and amazing advances in medicine such as the eradication of smallpox that killed 300 to 500 million people in the 20th Century. Society would do extremely well to not forget the stunning benefits that coal, oil and gas has provided.

What is shale gas?

Conventional oil and gas is formed at a depth of approximately 3000 m (10,000 ft) when mudstones (shale) rich in organic  matter (the source rock) are heated to about 100˚C and squeezed by burial to produce first oil and then gas as burial and temperatures rise. If the organic content is high, so much oil and gas are produced in the mudstone that it creates natural fracture pathways and escapes. Being lighter than water it floats upwards where some is trapped in either sandstone or limestone reservoirs (that act like sponges) that we commonly know as oil and gas fields. These are super-concentrated accumulations of energy (Figure 3).

In shale gas and shale oil, the organic content of the shale is lower and the gas and oil that is formed by the same processes remains trapped in the shale. These are  low grade concentrations of energy distributed through vast volumes of rock. The gas and oil does not escape because the shale is “impermeable”, that is it lacks connected holes big enough to allow fluids to flow through it. The drain in a shower is permeable. A drain covered in hair is not. A sieve is permeable. A sieve clogged with starch after straining rice is not.

Since shale is impermeable and has not given up its gas and oil for millions of years Man has invented a way of making it permeable, namely hydraulic fracturing (fracking). In fracking, a fracking fluid is pumped into the well at extreme high pressure so that the pressure in the well exceeds the confining pressure of the rock which then fractures, enabling the gas or oil to flow. This is tantamount to “blowing up the rock” deep down in the Earth’s crust. But that is only part of the story. Fracking shale only really works in long horizontal wells drilled along “sweet spot” horizons (Figure 3), where multiple fracking events may be conducted. Drilling long horizontal wells and conducting multiple fracks costs a lot of money and energy. How on Earth can shale gas be cheap?

Figure 3 From the US Energy Information Agency. Pools of conventional oil and gas flow freely to the surface whilst in shale the well is drilled along the gas rich zone and fracking shatters the rock to enable some of the trapped gas to flow into the well bore.

Intensity of development

Of the various environmental impacts discussed below, it is the intensity of shale developments, should they go ahead, that may give reason for concern. In the USA  good wells tend to produce between 2 and 5 million cubic feet per day at the start, declining to around 1 million cubic feet per day per well after 2 or 3 years. A universal feature is high decline rates, typically 40% in the first year and 20 to 30% in subsequent years [2]. This means that once you jump on the shale carousel you have to keep drilling to maintain or grow production – lots and lots of wells every year.

To place this in context, the UK currently consumes about 8000 million cubic feet of gas per day [1] and so to provide all of our gas needs from shale would require about 8000 wells.

On average fracking a well requires 1000 truck trips to transport material from and to the well site (email correspondence from a US Oil company CEO)

Another way to place this in context is to compare shale production with large conventional off shore gas fields. Initial flow rates from the Ormen Lange gas field in Norway were of the order 350 million cubic feet per day per well [3]. Initial production from the Marcellus shale of Bradford County is typically 4 million cubic feet per day per well. Thus around 88 shale wells may be required to replace a single offshore well.

Of course, if it was easy to find large new offshore gas fields in Europe then we wouldn’t be contemplating shale, but we can’t. Most of the large European oil and gas fields have already been found and the reserves used up. And of course, drilling shale onshore dispenses with the need for massive offshore structures and sub-sea pipelines.

The intensity of development should really only be of concern during drilling operations. In Bradford Co Pennsylvania, well spacings are typically 1 to 2 km (Figure 4). And so a neighbourhood may be inconvenienced for a few months while a well is being drilled, but then the drill crew packs up and moves on leaving a clean and tidy drill pad with a well head. But the drill crews may return at some future date to re-frack the well.

Figure 4 Vertical view of Figure 1. I count 9 shale wells, some with tailing ponds. The landscape is already 100% overprinted by Man and once the rigs are gone, the visual impact of the drill pads should not be too significant.

Gas wells also need to be connected to a processing plant by pipelines that will inevitably result in more disruption during the construction phase. The processing plant will take the form of a mini petrochemicals complex where ethane and longer chain hydrocarbons are removed and used by the petrochemicals industry and impurities like N2 and CO2 are removed and most probably vented.

The scale of shale drilling operations in the USA has been phenomenal. The shale miracle has been brought about by application of sheer American muscle. There are currently 1685 land rigs drilling in the USA (source Baker Hughes).  In the UK in October there were 2 land rigs drilling and 34 land rigs in the whole of Europe (excluding Turkey). If the UK and Europe are to emulate the USA then there will need to be an enormous up-scaling of onshore drilling equipment and materials and the accompanying supply chains. All this of course would be extremely good news for employment in the heavy industry sector.

Ground water contamination

The most commonly voiced concern about shale drilling and fracking operations is contamination of ground water by the fracking fluid. The Royal Academy of Engineering has conducted a comprehensive review of this and say the following [4]:

Concerns have been raised about the risk of fractures propagating from shale formations to reach overlying aquifers. The available evidence indicates that this risk is very low provided that shale gas extraction takes place at depths of many hundreds of metres or several kilometres. Geological mechanisms constrain the distances that fractures may propagate vertically. Even if communication with overlying aquifers were possible, suitable pressure conditions would still be necessary for contaminants to flow through fractures. More likely causes of possible environmental contamination include faulty wells, and leaks and spills associated with surface operations. Neither cause is unique to shale gas. Both are common to all oil and gas wells and extractive activities.

Of all the potential environmental risks associated with drilling shale, the risk to contamination of ground water can be reduced to extremely low levels.

Drilling a well also produces a large volume of drill cuttings (the smashed up rock), drilling mud and frackng fluid. Once the well is fracked, the fluid must be removed to allow the gas to flow. The drilling mud and fluids can become contaminated with heavy metals and naturally occurring radioactive isotopes. If large-scale shale drilling operations were to proceed, any government will require a plan for disposal of these by-products of the drilling process.

CO2 emissions

One of the biggest myths associated with shale gas is the notion that it can help reduce CO2 emissions. Burning natural gas instead of coal today can certainly reduce the rate of CO2 emissions (Figure 5). But this is only of any value to the greenhouse gas content of the atmosphere if the coal not burned today is never burned. Of course once we run out of gas to burn we will turn back to coal. The US is currently crowing about the reduction in CO2 intensity of its economy stemming from the shale revolution, but much of the coal not burned in the USA has simply been exported and burned else where, amongst other places in Britain.

Figure 5 A comparison of the CO2 intensity of various generating technologies by David MacKay [5]. In natural gas it is C-H bonds that are broken when the gas is combusted to form CO2 + H2O. In coal, it is mainly C-C bonds that are broken when it is combusted to form CO2 + CO2. Hence the much higher CO2 intensity of coal. A country can reduce its rate of CO2 emissions by substituting gas for coal fired power but attacking the shale gas wedge of the resource pyramid will simply mean the burning of more gas long-term that will ultimately mean higher not lower CO2 emissions.

The real emissions concern with shale gas should focus on the gigantic size of the resource should it be exploited globally (Figure 6). We are beginning to attack a new slice of the resource pyramid. Any government, genuinely concerned about long-term emissions scenarios would quite simply ban shale gas operations.

Figure 6 This estimate of global recoverable shale gas from the BGS [6] contains 6318 trillion cubic feet (tcf). According to BP [1] global gas reserves currently stand at 6545 tcf of mainly conventional reserves. Developing shale will effectively double CO2 emissions from natural gas and not reduce them.

In part 2 I will take a cursory look at the economics of shale and explain why Rex Tillerson CEO of ExxonMobil is losing his shirt. I will also take a look at potential shale gas developments in the UK and attempt to summarise the many facets of the shale gas debate.


1. 2013 BP statistical review of world energy
2. Marcellus shale gas Bradford Co Pennsylvania: production history and declines
3. Norsk Hydro Tests First Ormen Lange Gas Production Well
4. Shale gas extraction in the UK: a review of hydraulic fracturing June 2012
5. Potential Greenhouse Gas Emissions Associated with Shale Gas Extraction and Use
6. The Carboniferous Bowland Shale gas study: geology and resource estimation

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19 Responses to Shale gas myths and reality – part 1

  1. Hugh Sharman says:

    Thanks again Euan. Very useful. The Google map is very helpful. I hope you can quantify the net energy gain from shale gas and oil from US operations. It is clear that the process is energy intensive. But we lack the numbers

  2. G. Watkins says:

    Clear and informative as usual. Well done and much appreciated. I look forward to the next instalment.

  3. Roger Andrews says:

    A few comments:

    “Since the middle of the 19th century growing supplies of cheap fossil fuels …. powered industrial society enabling global population to explode to 7 billion souls ….. This era is coming to an end.” It can be argued that the era of “cheap” fossil fuels actually ended with the 1974 oil embargo (inflation-adjusted oil prices are about the same now as they were in 1981) and that the global population explosion was largely unrelated to energy availability in industrialized nations.

    “We are running scarce of cheap fossil fuel.” Substitute “potentially economic” for “cheap” and fossil fuel reserves are larger than they’ve ever been.

    “Of course once we run out of gas to burn we will turn back to coal”. Maybe not. By that time wind and solar might even be cost-competitive.

    “The US is currently crowing about the reduction in CO2 intensity of its economy stemming from the shale revolution”. And why not? The US took a lot of flak for not signing on to Kyoto yet over the last few years has reduced its CO2 emissions more than any of the developed countries that did – and without any emissions reduction legislation. A lesson there, I think.

    “ … but much of the coal not burned in the USA has simply been exported and burned elsewhere ..” Actually not very much. According to EIA statistics quarterly US coal production decreased by 56 million tons between 4Q 2008 and 2Q 2013 but exports increased by only 7 million tons.

    “Any government, genuinely concerned about long-term emissions scenarios would quite simply ban shale gas operations.” France is the only major country that has so far banned fracking, apparently preferring to import gas from Russia (and on top of that it now it proposes to cut its nuclear generation by a third by 2025, raising questions as to whether the incumbent President is in full control of his faculties). As a practical matter, however, the only country that by itself could make a measurable dent in global CO2 emissions is China, which could reduce them 5-10% by converting all of its coal-fired plants to gas. But if China banned shale gas operations this option would of course no longer be open.

    • Euan Mearns says:

      Roger, The oil price SPIKES of 1974 and 1979 were transient geopolitical events, caused much grief at the time and then passed by with the growth of the N Sea and N Slope. The situation now is totally different with the cost of marginal supply >$80 / bbl. If prices fall, so does supply, prices go up again. Part of the global population explosion is linked to prosperity in the OECD since we provide the inoculations and medicines preventing millions of premature deaths, but it is the expansion of energy consumption in the DEVELOPING nations that underpins population growth there.

      The concept of reserves is linked to price, hence more reserves with higher prices. Question is for how long can our society continue to function with rising energy prices.

      On US emissions, I’m not at my desk, but per capita FF consumption in USA is something like 50 to 100% higher than rest of OECD, ex Canada that consumes even more. The US wants to export gas to push up prices so they can actually make money on it, and then expect a return to coal. I may be wrong, just don’t see the US closing down its coal industry and leaving the stuff in the ground.

      Thanks for stats re US exports – good to have someone checking facts;-)

      China could reduce its emissions a lot more by going from coal to nuclear. If you smoke 40 a day and are concerned about lung cancer you stop smoking, you don’t cut down to 30 a day. But the point you make is a reasonable one – China along with the USA would have to make a binding commitment to leave its remaining coal in the ground. I dare say though, that China will be pursuing shale because it is running short of energy – keeping coal production growing at 10% per annum becomes increasingly difficult for every year that passes.

      • Roger Andrews says:


        You ask: “Question is for how long can our society continue to function with rising energy prices?” Here are a couple of XY plots of world GDP growth vs. real oil prices between 1970 and 2012 that might be of interest:

        The first plot shows all the data with a one-year lag in oil prices, which gives the best correlation coefficient, although not a very strong one (R=0.4). As we would expect it shows global economic growth tending to decline as the price of oil increases.

        The second plot removes the data before 1974 (a bygone age) and data from the four years that the IMF classifies as “global recession years” (1975, 1982, 1991 and 2009). With these years gone there’s little relationship between oil price and GDP growth.

        I interpret these results to mean that oil price spikes cause recessions but that outside recessionary periods oil prices have had little impact on global economic growth, or at least not so far.

        Regarding the US coal industry, I don’t see it shutting down completely either, but the future looks bleak:

  4. Joe Public says:

    Very informative, Euan.

    I struggle with this statement:- “Any government, genuinely concerned about long-term emissions scenarios would quite simply ban shale gas operations.”

    That government would have to then import viable alternatives.

    One factor often forgotten / ignored about ‘natural’ gas is its relatively high point-of-application efficiency. Transmission losses are relatively small.

    • Euan Mearns says:

      Joe, this comes down to the concept of a resource pyramid. Any government genuinely concerned about emissions would never sanction development of non-conventional hydrocarbons like shale gas or tar sands – unless you combine it with CCS, which is bonkers IMO. The Canadians understand this and have left Kyoto. If you are concerned about emissions the only way to tackle the problem is to leave FF in the ground. But this presents a real paradox, what to use instead. The only viable solution IMO is nuclear. But lets look at this another way. Repeal the Climate Change Act and work out the best way to deliver affordable, secure indigenous energy for the UK. Shale gas may have a role in that scenario – if we ever find any! But the secure answer still comes back to nuclear.

      • Joe Public says:

        Agree about Nuclear. But the UK also needs security of supply for our established gas market.

        • Euan Mearns says:

          Gas has two big applications, power generation and home heat. Nuclear can take care of the former. Shale gas may help with the latter if we find any and if the public permits its development, which I doubt . So I see electrification of home heating and following the mantra of energy efficiency that would mean air source heat pumps. Although resistance heaters are already 100% efficient, cheaper and easier to install. Electric cookers of course already exist. Folks will make a decision on price. If nat gas prices keep going up and nuclear electricity works out cheaper then folks will switch. Before 1970 we didn’t have nat gas.

          • Joe Public says:

            “Gas has two big applications, power generation and home heat. ……….. Although resistance heaters are already 100% efficient, cheaper and easier to install. ”

            I disagree.

            1. It’s virtually always more efficient to transport the fuel to the point of use.

            2. The electricity network would not be able to cope with the transmission demands of the country’s space-heating load. It could cope with supplying heating to many houses; but not the majority of factories, offices, warehouses, shopping centres etc.

            3. By definition, all space heating loads are Maximum-Demand occurrences – the very load-profile the ‘leccy industry struggles to cope with. Electricity is virtually un-storable; gas has line pack. Every kW of electricity used within the ½-hour of maximum demand pushes-up the price of all electricity used within the 2-month period.

            4. Resistance heaters are only 100% efficient at the point of use; just like electric cars emit no CO2. The transmission losses are not to be underestimated – a 100 mile 765 kV line carrying 1000 MW of energy can have losses of 1.1% to 0.5%. A 345 kV line carrying the same load across the same distance has losses of 4.2%.

            5. The long-term pragmatic solution could be micro-CHP. I seem to recall British Gas (before it was disbanded as a commodity+distribution entity) researched the practicalities of a 250cc (?Yamaha?) motorcycle engine using Nat Gas to meet a household’s entire demand for power generation, with space heating & water heating from the engine’s waste heat.

          • Alister Hamilton says:

            Hi Euan,

            We’ve just gone all electric at home (except the hob, which will get replaced with an induction hob when we do up the kitchen next year). Gas boiler eventually packed in after 16 years with no spare parts available. Looked at air source heat pumps (ASHP). Liked what I saw coming out of Japan where they use Carbon Dioxide as the working gas to get much better ASHP performance. Got involved with the installation of these units in the UK. Dimplex are now doing some great things with ASHPs in the UK which should greatly improve the customer experience. We decided to go for infra red heating in the end ( Replaced the boiler (around 24 kW) with 6.2 KW of IR panels. Heat and controllability (Honeywell Evotouch) is absolutely superb. Using overnight electricity to provide domestic hot water in a Dimplex tank. Drive an EV. Running costs (a bit early to say) should be about the same as our previous gas system. Energy security greatly improved (Scotland being a net electricity exporter).

            Best wishes,


  5. Joe Public says:

    OFF (specific) TOPIC, but the only way I could communicate the observation:

    Your informative posts generally report in the ‘units’ of the subject’s industry or even subject’s industry’s country. As a result, comparing energy values across postings becomes challenging.

    Could you add a Widget or cross-table of fuel/energy conversion factors near the top of your Home Page?

    I suspect the unit most of your readers would have greatest familiarity with, is kW / kWh, from their personal energy bills. So then using appropriate SI prefixes would enable easier comparisons of your stories across different industries.

    BTW – “European primary energy production peaked at 1136 million tonnes oil equivalent (mmtoe) …..” contains one-too-many ‘m’. [Ironically, referring to gas units, mmBtu (or even MMBtu) representing one million Btu, is acceptable across the pond, but not in Britain. i.e. 10 Therms / 293.1 kWh] QED(?)

    The IEA/OECD define one toe to be equal to 11.63 MWh, or, 41.868 GJ; but again I have a feeling some less-technical of your readers might struggle to comprehend a Joule.

    • Euan Mearns says:

      Joe, good idea regarding unit conversions. Something I’ve been meaning to do. Struggle with this myself a lot of the time, especially with gas – btu in USA, therms in UK, KWh if you’re National grid, tcf if you are a geologist, BCM if you are a european geologist – its a nightmare. Get around to a widget some day soon. Re mm – in petroleum geology (my background) m=thousand and mm=million, but I’ve run into trouble with this before – best to write things out in full.

      • Joe Public says:

        “Struggle with this myself a lot of the time, especially with gas – ………. therms in UK, KWh if you’re National grid, ”

        You’re not he only one.

        In the mid 1990’s after the UK gas market had been opened up, Shippers had to nominate/buy their day-ahead units.

        One day there was a massive spike in prices. Apparently one Shipper had committed to buy/sell xTherms when the trading unit was kWh. It was lumbered with 29.3 times as much as it needed that day.

  6. Hi Euan,

    Terrific post. I like the find the pad game. I will try it on my class on Tuesday. When the pads are among the fields, it makes an important point that environmental impacts of drilling are completely overwhelmed by the environmental impacts of agriculture.


    • Euan Mearns says:

      Hi Dave, if you go to N Dakota or Texas, in the wilds, where you have to build access roads etc, the impact looks much worse where all you see is the shale pads and roads – in areas where there are no / few people. I find it difficult to judge the impact on rural England. 1000 truck loads of stuff / well sounds a lot, but we probably have 10,000 truck loads of stuff ploughing up and down our roads every day. This has become a very polarised debate in UK already – and we ain’t found any shale gas yet!

      Looking around PA for shale pads, I found some legacy areas of old oil field developments – tight spaced wells with donkeys on em. You guys have drilled and drilled a lot of wells over the years. The intensity of shale developments is much more spread out.


  7. Euan Mearns says:

    Although resistance heaters are already 100% efficient, cheaper and easier to install. ” I disagree.

    Hi Joe, in the not too distant future I’m to do a couple of posts on the DECC 2050 calculator. Part of what I was saying was paraphrasing Hot Air – but I can’t recall the details of what MacKay said. Where I’m coming from is that gas (is Europe) is going to become scarce and expensive – amongst other things Norway and Holland will some time soon follow UK gas production down. I look at my own house and contemplate air source heat pumps – we still use gas and a very old boiler – but the gas bills are really beginning to hurt. And I know that resistance heaters (panel ovens) are much cheaper to install than air source system. And I’d like to have a wood burner, simply because I like chopping and burning wood.

    The interesting thing for me in your reply is the capacity of the grid to cope with electrification. The 2050 calculator is very clever (or maybe you know otherwise, it will the subject of one of my posts) and gives you costs of different pathways. And os there will be good questions to ask at that time if the calculator factors in grid hardening costs. I’m hopeful that David MacKay may turn up to answer questions.

    The micro CHP system sounds interesting, but at the moment its not the sort of thing I’d contemplate. In future, decisions will be driven by price, future costs and convenience. E

  8. Euan Mearns says:

    @ Alister

    We’ve just gone all electric at home

    Would be interested to hear a lot more about your experience with this. Replacing 24 with 6.2 KW is in itself interesting. But what are IR panels – my experience with IR (infra red) in the past is toasty skin, cold air.

    I live in a 1929 granite semi in Aberdeen. We replaced all windows with good quality, Douglas fir framed double glazing. Have good outer doors, each with inner hallways. And loads of insulation up top. The house is cozy, but old boiler has to go. Maybe next year we re-do that bit of the house and install a condenser on an outer wall+ a wood burner in the fireplace where the boiler sits at present. Been talking about this for about 5 years now.

    The cost is always high and I’m interested in the discounted sums folks have done to make a leap. And also to make government aware of the high cost of being efficient. Regarding security, Scotland asyou know has 2 nukes, that will not be replaced under present regime – there’s going to be loads of discussion about this here in the year ahead. In my 2050 scenario I go all nuclear electric.


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