Second Edition 09 June 2011

As a result of publishing this essay on 08 June 2011, I received, by various means, some 30 messages, most of which were positive. However, some pointed out some errors or other points of omission or commission. In order to preserve the original format, this second edition will attempt to correct these, but in an appendix before the Reference Links, which will also be expanded from 12 to 20. Any reference from the original text to the appendix will take the form, e.g., [*1]. These are not in textual order.

Fossil hydrocarbons (oil and gas) extracted from shale beds have become a controversial and hotly debated subject. This essay attempts to take the extremes out of the arguments. However, it must be stated that all fossil fuels, no matter how they are extracted from the Earth, add to the carbon dioxide loading of the atmosphere [*2]. As such, apart from the controversial aspects of shale hydrocarbons, they can never be the answer to our climatic dilemma, even though some interested bodies in the USA pretend that this may be so [1].

What is shale?

Shale, showing lamellar structure Photo: Wikipedia

Millions of years ago, mud in estuarine channels, in particular, was deposited layer upon layer.[2] This sediment accumulated in very thick deposits. As it did so, vegetable and animal matter washed down by the rivers or tides was co-deposited. In time, the layers of mud and organic matter became compressed under the weight of later deposits. This compression continued as later rocks formed above the mud layers. Over millions of years, the mud coalesced into thin layers of hard, impermeable rock. The layers can be easily split but the impermeable rock cannot easily be broken in the third dimension. The organic matter was transformed into hydrocarbons in the form of oil and gas, of very variable composition, according to where it happened. The total fraction of hydrocarbons may vary from about 0.5 to 25%. Today, the strata of shale, often tens of metres thick, may lie at very great depths which would make conventional mining impossible or uneconomical.

Shale can be found in large deposits in many places. Two of the largest – and most controversial – areas can be found in some of the eastern states of the USA, notably New York, Ohio, W. Virginia and Pennsylvania.[3][4] It has been said that these deposits alone could provide the totality of the US demand for natural gas for many years. However, they are not the only deposits in the USA; over half the states have exploitable quantities of shale. In Europe, there are large deposits in the UK, Germany, Poland and elsewhere [*3].

To diverge into US politics, George W. Bush, in 2005, introduced into law the Energy Policy Act that, as far as possible, the USA should be self-sufficient in the provision of fossil energy, in order to reduce their dependence on foreign imports. This act gave the impetus to the exploitation of shale hydrocarbons. Unfortunately, there was a clause, nicknamed the Halliburton loophole, which exempted persons and companies from complying with the Federal Water Pollution Control Act (33 U.S.C. 1362) [5], which ensures the right of everyone to clean drinking water. This has been the origin of a major part of the controversy surrounding the exploitation of shale hydrocarbons. It is around this problem that New York State has issued a moratorium preventing new exploitation of shale hydrocarbons until the environmental impact has become clearer. This has been copied by the province of Québec. A certain amount of opposition is mounting in Europe for the same reasons. This opposition has evoked an award-winning film [6] and several videos [7] to be published.

The exploitation of shale hydrocarbons

To understand the problems engendered by exploiting shale hydrocarbons, it is necessary to understand how this is done. I offer below a brief résumé of the process, without going into the greatest detail [8].

The first stage of the process is to drill a borehole which curves round to become horizontal through the stratum of shale. As this may go down to thousands of metres, the sheer volume of detritus made into mud with drilling fluids can be very high. The most usual types of drilling fluids are water-based and contain chemicals such as bentonite, formic acid, organic sodium and potassium salts etc. To these are added other chemicals leached from the rock cuttings. It is therefore clear that this mud, in itself, as it exits from the top of the well, is a potential pollutant, unless it undergoes expensive water treatment. In addition, if the well passes through an exploited water table, then the water is likely to become polluted and unsuitable as a source of drinking water. After the borehole has been completed, steel pipes of a narrower bore are inserted to the practical end and a cement slurry is pumped down with sufficient pressure for it to come back round the outside of the pipes to the surface. This provides a casing which is not necessarily homogeneous or of constant thickness. This casing is quite controversial in itself because it does not necessarily provide the optimum protection. One illustration of casing failure was in the desperate measures used to contain the leak of the 2010 catastrophe in the Gulf of Mexico.

After the casing has set, a device causing a number of small controlled explosions is inserted down into the level of the shale stratum. These explosions are designed to break open the casing at the points where it is desirable to remove the hydrocarbons and to prime a small amount of cracking in the shale. At this point, I shall assume that the hydrocarbons are in the form of "natural" gas, because the heavier species require a different treatment which is not necessarily relevant to this essay.

The next part of the process is called hydraulic fracturing, more commonly abbreviated to "fracking" or "fracing". This consists of pumping down very large quantities of water, with additives, at extremely high pressures. These pressures are sufficient to crack or fracture the primed shale beds over large distances, to allow the "tight", imprisoned, gas to travel back to the borehole, from which it can be extracted for exploitation. In order to understand the environmental impact of this process, let us have a look at the additives to the water [9]. One of the most important ones is the "proppant", most commonly a coarse sand, although other materials are sometimes used. This "props" open the cracks which are formed by the fracking, to allow the free flow of gas. The quantity by percentage of proppant is small, typically 1 to 4% of the water volume and it is inert so does not, in itself, create a great environmental hazard. The chemicals which are added to the fracking fluid are also small in volume, typically about 0.25-0.5%. Some 500 different chemicals have been reported as additives to the fluid. Typically, these may include an acid, such as hydrochloric acid, to dissolve calcareous deposits, a lubricant such as polyacrylamide to assist the proppant to penetrate into the cracks and a biocide to prevent the propagation of microorganisms which could block the gas flow. It could be argued that such low percentages of these additives would be harmless until one considers that fracking uses literally many millions of litres of water at pressures up to 10,000 atm or bars. This implies many thousands of litres of additives per fracking operation and this is not negligible.

After the fracking operation is complete, some of the fluid is pumped back out and recovered. Theoretically, this should be transported away for water treatment and this is done by responsible companies. However, many small enterprises simply allow it to drain into the nearest river or creek, causing grave environmental problems. This fluid contains not only the additives, but a considerable amount of gas and other hydrocarbons as well as substances leached from the rock, which add to the pollution, often killing fish and other wildlife. The quantity of fluid that is recovered varies from about 25 to 60% of the quantity injected. The remainder frequently enters into porous strata above and below the shale. In many cases, the fluid travelling upwards enters into water tables, rendering them unsuitable as sources of drinking water, not only because of the chemicals, but also because of the dissolved gases. This is one of the major problems engendered by fracking and the reason why New York State has imposed its moratorium. There are many examples shown on Internet videos of the flammability of drinking water due to the release of hydrocarbon gases. Even if the fracking is confined to the shale stratum, this does not mean that the fluid or gas cannot enter into aquifers through cracks in the fragile cement casing round the borehole. The overall process has been described in a BBC documentary [10], not quite impartially but nearly so

The gas coming from the borehole, after it has been capped, is usually saturated with water vapour, which has to be removed by adsorption or by cryogenic dehumidification. The composition of the gas is very variable, according to the location of its origin. It is mainly organic, to the extent of about 60% to 95%, but its methane content can vary from as low as 0.5% up to 85%, most often considerably more than 50%. This gas must be purified to typically 98% methane to allow it to be used as natural gas. This implies a considerable number of processes to remove each kind of impurity including the inorganic ones. Some of the impurities can be relatively dangerous, as heavy metals, other toxins or even as a radioactive radiation from uranium and radon (most shale gas is a gamma emitter; one reference even evokes radium).

Problem areas

Even with this summary of the process, it can be seen that there is a strong risk of environmental hazards as a result of fracking shale beds. This does not mean that it is impossible to exploit shale gas safely, but it does mean that it is difficult and extreme precautions must be taken. One of the worst hazards is that, if the fracking extends into porous layers above the shale bed, methane and other gases can actually diffuse directly into the atmosphere. As methane has a relatively high Global Warming Potential, it is probable that the overall effect for climate change would be greater than the exploitation of coal as a fossil fuel. This would be exacerbated by fugitive emissions of the methane during the purification and distribution processes. It is therefore understandable that many activists oppose the fracking of shale beds [12].

The areas of New York State and Pennsylvania where the exploitation of shale gas is highest are essentially rural, with a very low population density. Although a considerable number of persons have been negatively affected, this has not been to a catastrophic level (except, perhaps, for the individuals concerned). This process has not yet been exploited to any great extent in Western Europe. The population density throughout Western Europe is much higher and there is therefore a greater risk of negative impacts amongst the inhabitants if things go wrong. At the present moment, some experimental boreholes have been drilled in Lancashire, England, in the region of the city of Preston. This is in the centre of a subregion with a population of about 335,000. If something were to go wrong here, the effects could very well become far-reaching. In my opinion, it is therefore very important that any fracking operations in populous areas must be very carefully monitored and all precautions taken to prevent accidents of any nature.[*1]

*Appendix for second edition (reactions from feedback)

Seismicity

[*1] It was pointed out to me that two minor earthquakes, believed to have been caused by the fracking of the boreholes in Lancashire, mentioned above, occurred. These resulted in the suspension of activities pending scientific investigation [13]. 'Googling' revealed a number of reports of seismic activity in the USA, but little other than vague media reports. The same reference [13] indicates that proposals have been made to frack some exploratory boreholes in S. Wales but the company concerned appears to have taken a rather cavalier attitude to the risk of environmental damage, "The Wales Green Party has called for a moratorium on fracking, but Bridgend-based Coastal Oil and Gas argues that strict regulation will prevent environmental damage."

I quote one correspondent in full [14], "The wells are nearer Blackpool than Preston. They're all within 3-4 miles of me.

"Interestingly we've had two (very small) eatherquakes in the area which seem to have corresponded to the first trial fracking and re-starting fracking after a pause. The epicentre of one was less than a mile from me. These are only around magnitude 2 so hardly noticeable, but it if they are related to the fracking then there is a concern that when much large scale fracking is done we might get bigger quakes.

"I should add that any quake in this area is rare. We do get shakes from time to time, but they tend to be from larger quakes much further away (1[00]-200 miles away). I've never heard of minor quakes like these, but perhaps we've always had them and they're only being reported now because someone wants to highligh the possible connection to fracking."

The most interesting document on the seismicity of fracking [15] has nothing to do with oil or gas exploration but the fracking of granite during the exploration for a geothermal power station in Switzerland. During the fracking of an exploratory well, an earthquake of magnitude 3.4 occurred, causing some damage to property. The exploration was suspended, as a result. An important point brought out in this report is the difference between induced and triggered seismicity. Induced seismicity is caused by the fracking operation itself, while triggered seismicity is a natural earthquake where tectonic tensions have been relieved by the fracking. The latter could be severe in zones where faultlines occur.

US Environmental Protection Agency

It is true that I have not mentioned the EPA. One correspondent, citing the EPA, trashed the risk of methane contamination of drinking water as a result of fracking [16]. A good search found nothing to substantiate this claim. However, it was found that the EPA have started a scientific study of the subject, to be completed in the second half of 2012 [17].

The economics of fracking

I purposely kept the question of the economics in a low-key. Various correspondents have evoked the subject. It would seem that opinion is divided between those who believe that fracking will be the economic saviour of fossil fuel supply and those who believe that the only profits will be made by the energy companies [18].  I don't propose to enter into this debate other than to cite one person who considers it possible that the energy companies will use it as a form of moral blackmail, pretending that energy companies will increase tariffs, unless they are allowed to frack [19]. I think that this view is rather extreme and I certainly do not share it, for lack of proof.

Climate Change

[*2] Interestingly, no correspondent has evoked the problems of climate change either from the combustion of natural gas produced by fracking or from the fugitive emissions of raw natural gas into the atmosphere. Is this because of climate change fatigue?

France

[*3] I omitted any mention of France in the list of interested countries. A correspondent living in Paris has published a series of maps showing where fracking has taken place and is taking place [20]. I am rather disturbed at the possibility of development within a radius of about 100 km around Paris, because this forms one of the largest Artesian basins and is a major source of water for the capital. 

Reference links

[1] "Simply put, deep shale gas formation development is critical to America's energy needs and economic renewal." http://www.hydraulicfracturing.com/Pages/information.aspx

[2] "Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments (silt-sized particles) of other minerals, especially quartz and calcite." http://en.wikipedia.org/wiki/Shale

[3] "Named for a distinctive outcrop near the village of Marcellus, New York in the United States,^[3] it extends throughout much of the Appalachian Basin.^[4] " http://en.wikipedia.org/wiki/Marcellus_Formation

[4] "The Utica Shale occurs in outcrops in the state of New York^[1] and in the subsurface in the provinces of Quebec and Ontario.^[3] It has recently become the target of gas and oil exploration in eastern Ohio and Pennsylvania where it exists around 8,000 feet deep." http://en.wikipedia.org/wiki/Utica_Shale

[5] "Energy Policy Act 2005 ,Public Law 109–58, 109th Congress

SEC. 323. OIL AND GAS EXPLORATION AND PRODUCTION DEFINED.
Section 502 of the Federal Water Pollution Control Act (33 U.S.C. 1362) is amended by adding at the end the following:
‘‘(24) OIL AND GAS EXPLORATION AND PRODUCTION.—The term ‘oil and gas exploration, production, processing, or treatment operations or transmission facilities’ means all field activities or operations associated with exploration, production, processing, or treatment operations, or transmission facilities, including activities necessary to prepare a site for drilling and for the movement and placement of drilling equipment, whether or not such field activities or operations may be considered to be construction activities.’’." Page 102 of http://doi.net/iepa/EnergyPolicyActof2005.pdf

[6] "When filmmaker Josh Fox is asked to lease his land for drilling, he embarks on a cross-country odyssey uncovering a trail of secrets, lies and contamination." Award-winning activist film, Gasland. http://www.gaslandthemovie.com/about-the-film/ Two trailers at http://www.youtube.com/watch?v=dZe1AeH0Qz8 and http://www.youtube.com/watch?v=z0fAsFQsFAs Also the opposite activist view of the energy industry in Debunking Gasland at http://www.energyindepth.org/2010/06/debunking-gasland/

[7] "An original investigative report by Earth Focus and UK's Ecologist Film Unit looks at the risks of natural gas development in the Marcellus Shale. From toxic chemicals in drinking water to unregulated interstate dumping of potentially radioactive waste that experts fear can contaminate water supplies in major population centers including New York City, are the health consequences worth the economic gains?" An activist anti-fracking video, Fracking Hell: the Untold Story, at http://www.youtube.com/watch?v=dEB_Wwe-uBM

[8] "In order to maximize the production potential for a natural gas well, the shale formation must be hydraulically fractured. This video outlines and demonstrates the hydraulic fracturing process in Chesapeake Energy natural gas operations." A smooth energy-industry explanation video of fracking at http://www.youtube.com/watch?v=73mv-Wl5cgg&NR=1

[9] "Natural gas drillers are doing too little to inform the public about the chemicals used in hydraulic fracturing, a practice essential for tapping the United States' shale gas reserves, a Chevron executive told a federal panel" http://www.reuters.com/article/2011/06/02/us-usa-natgas-fracking-idUSTRE75134D20110602

[10] "Hydraulic fracturing, a process known as fracking, is a controversial way to get at natural gas trapped in shale rock a couple of miles underground. Cleaner than coal, it is being hailed by some as the latest energy solution. But some people who live near drill sites claim the process has contaminated their water supply with methane. Newsnight's Science editor Susan Watts reports." A somewhat more impartial BBC TV reportage, leading from the US to the UK context at http://news.bbc.co.uk/2/hi/programmes/newsnight/9255520.stm

[11] "A purification plant is an important infrastructure and one plant may serve many wells over a considerable area, with a spider's web of small bore pipework. This is often cast iron pipes with flanged joints, notable for leaks. At the wellhead, there is a "tree" for initial separation of gross impurities, including sand, by purging them out with the gas." http://www.cypenv.info/worldee/files/fossilfuel/natural_gas.aspx

[12] "Natural gas is not the least polluting of fossil fuels, as the large oil producers would have us believe. In terms of purity, it is good, but greenhouse gas emissions are holistically very high from its use." http://www.cypenv.info/worldee/files/fossilfuel/natural_gas.aspx 

[13] "But Cuadrilla announced a halt to exploration, saying: “No fracking will be resumed until the data has been interpreted by ourselves in consultations with the British Geological Survey (BGS).” The BGS flagged up the possible dangers of fracking in its response to the April quake, stating: “Any process that injects pressurised water into rocks at depth will cause the rock to fracture and possibly produce earthquakes.”" http://www.walesonline.co.uk/news/wales-news/2011/06/01/vale-fracking-plans-should-halt-after-earthquakes-strike-in-lancashire-91466-28798601/#ixzz1OmQ82LiT

[14] http://www.weather-watch.com/smf/index.php/topic,51434.msg413586.html#msg413586

[15] "A thorough evaluation of site specific risks should be required for future geothermal project developments in Switzerland. The findings of this Basel study constitute an important data point for future risk assessments. After analyses of the data acquired by the suspended project and after comparison with experiences made in other similar geothermal projects, we consider the Basel earthquakes caused by the geothermal project has exceptionally strong." Deep Heat Mining Basel, Seismic Risk Analysis, Serianex. http://esd.lbl.gov/files/research/projects/induced_seismicity/egs/baselfullriskreport.pdf

[16] "EPA recently reported there have been no cases in the US where water has been affected by the fracking itself. Those incidents where contamination was present were found to have been caused by degraded/faulty pipes or other intermediate gear, or by natural sources like nearby bogs or disposal sites. The infamous clip of a guy setting fire to water in his sink was due to a natural methane source leaching into his well." http://www.forums.murc.ws/showpost.php?p=683562&postcount=5

[17] "EPA announced in March that it will study the potential adverse impact that hydraulic fracturing may have on drinking water. To solicit input on the scope of the study, EPA is holding a series of public meetings in major oil and gas production regions to hear from citizens, independent experts and industry. The initial results of the study will be announced in late 2012. EPA will identify additional information for industry to provide – including information on fluid disposal practices and geological features – that will help EPA carry out the study. " http://yosemite.epa.gov/opa/admpress.nsf/d0cf6618525a9efb85257359003fb69d/ec57125b66353b7e85257799005c1d64!OpenDocument

[18] "Here in the southern tier of New York my location is at the heart of the debate.  Being within a few minutes drive of both Susquehanna and Delaware rivers and Cannonsville and Pepacton reservoirs for NYC drinking water, I hear about this topic everyday on the news. 

There are two sides to the argument: 1. Possibility damaging the drinking water for millions 2. A serious influx for cash...." http://www.weather-watch.com/smf/index.php/topic,51434.msg413593.html#msg413593

[19] "Just to push the button further, on the BBC yesterday, One of the Scottish Gas companies is increasing gas prices by 19%, after already having increased them in January.
I think they will all (gas companies) hike up the price of gas, and then say "If we Frack, the prices can go down". In other words, they are basically going to blackmail the populace into accepting Fracking. Corporate greed rules the world" .http://www.forums.murc.ws/showpost.php?p=683554&postcount=2

[20] "This is a map of France with some of the existing plots, and where they have asked for more plots to prospect." http://www.forums.murc.ws/showpost.php?p=683557&postcount=4