Hydraulic fracturing in the United Kingdom

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Scale diagram of a shale gas well showing large separation between aquifer and shale source rock

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Scale diagram showing how many wells can drain gas from a large area from a single pad

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A well from drilling to abandonment

Although hydraulic fracturing in the United Kingdom has been common in North Sea oil and gas fields since the late 1970s, and has been used in about 200 British onshore oil and gas wells since the early 1980s, the technique did not attract public attention until its use was proposed for onshore shale gas wells in 2007 and 2008. Although hydraulic fracturing is often used synonymously to refer to shale gas and other unconventional oil and gas sources, it is not always correct to associate it with unconventional gas.

In the United Kingdom, as in other countries—and in particular the United States, where the industry is most advanced and widespread hydraulic fracturing has generated a large amount of controversy.

The European Union has also issued an approval for hydraulic fracturing under certain conditions from January 2014. It recognises that it can be an economic boost but there is a need to not repeat the pollution incidents that have occurred in the US.

The process was suspended in the UK between June 2011 and April 2012 after triggering minor earthquakes, but a report into the incidents concluded that earthquake risk was minimal, and recommended the process be given nationwide clearance. The Royal Academy of Engineering published this report in June 2012, highlighting certain concerns, that lead to a raft of regulation for the industry. A detailed briefing paper was issued in late 2015 for the Houses of Parliament. This gives a full review of current thinking.

History

The first experimental use of hydraulic fracturing was in 1947, and the first commercially successful applications of hydraulic fracturing were in 1949. In the United Kingdom, the first North Sea well hydraulic fracturing was carried out shortly after discovery of the West Sole field in 1965. First hydraulic fracturing from ship was conducted in the United Kingdom in 1980. Onshore, approximately 200 wells have been hydraulically fractured which is about 10% of all onshore wells in the United Kingdom. It includes Wytch Farm, which is the largest onshore oil field in western Europe.

Worldwide, massive hydraulic fracturing was first used in thousands of gas wells in the western United States in the early 1970s. Massive hydraulic fracturing spread in the late 1970s to western Canada, Rotliegend and Carboniferous gas-bearing sandstones in Germany, Netherlands onshore and offshore gas fields, and the United Kingdom sector of the North Sea. As of 2012, 2.5 million hydraulic fracturing jobs have been performed on oil and gas wells. The US Dept of the Interior/USGS published a detailed history of the process in the US.

The surge of public interest in shale hydraulic fracuring in the UK can be traced to 2007, when Cuadrilla Resources was granted a licence for shale gas exploration along the coast of Lancashire. Cuadrilla has American-Australian-British ownership, though close ties have developed between China National Offshore Oil Corporation (CNOOC) and one of Cuadrilla's backers. The company's first and only hydraulic fracturing job to date was performed in March 2011 near Blackpool. Cuadrilla halted operations at Lancashire drilling site due to seismic activity damaging the casing in the production zone. Other companies, including Eden Energy, UK Methane Ltd, Coastal Oil and Gas, Celtique Energie, and IGas Energy, have obtained exploration licences, with test drilling being carried out in Somerset, Glamorgan, Cheshire and other locations.

On 17 December 2015 the Oil and Gas Authority (OGA) announced 159 new onshore blocks are being formally offered to successful applicants.

Method

Hydraulic fracturing is a well-stimulation technique in which rock is fractured by a hydraulically pressurized fluid. A high-pressure fluid (usually chemicals and a proppant suspended in water) is injected into a wellbore to create an extensive system of small cracks in the deep-rock formations through which natural gas, petroleum, groundwater (in the case of water wells) and brine will flow more freely. In horizontally drilled sections, it is common to perform as many as 30 separate fracture stages, to evenly divide the production zone. When the hydraulic pressure is removed from the well, small grains of hydraulic fracturing proppants (usually sand but aluminium oxide, or ceramic beads may be used) hold the fractures open when the pressure is released. The bulk of the additives are usually the proppant, up to 10%, but other chemicals designed to reduce water viscosity, and to modify other fluid properties may also be added, at quantities typically less than 1% in total. One of the main differences between hydraulic fracturing in different countries is the usage of chemicals. As of December 2014, the only chemical additives that have been permitted by the Environment Agency in the United Kingdom were 0.075% of polyacrylamide friction reducers, 0.125% hydrochloric acid and in rare cases 0.005% biocide.

Gels, foams, and compressed gases, including nitrogen, carbon dioxide and air can be injected in place of water. Fracturing fluids have been developed using liquefied petroleum gas (LPG) and propane in which water is unnecessary. There is sometimes a need to fracture at shallower depths in coalbed methane wells and these methods can be used. The extent of natural fracturing in the coal would determine if this was necessary. Hydraulic fracturing methods such as these will use a much smaller volumes of fluid.

Areas with hydrocarbon potential

Main article: Shale gas in the United Kingdom

Oil well in Lincolnshire. Many such as this have been hydraulically fractured.

Although the first shale gas well was drilled in England already in 1875, only hydraulic fracturing combined with horizontal drilling is likely to enable commercial extraction of unconventional hydrocarbon resources, such as shale gas and light tight oil, in the United Kingdom. The largest resource is expected to be the Upper Bowland Shale of the Pennine Basin in Lancashire and Yorkshire.

A BGS/DECC report from May 2014 suggest that there is the possibility for the extraction of light tight oil (LTO) in Weald Basin and the average figure of 4.4 billion barrels (700×10^⁶ m³) is suggested. The overall range of estimations is from 2.2 to 8.6 billion barrels (350×10^⁶ to 1,370×10^⁶ m³). The data is said to have a "high degree of uncertainty", and the amount that could be produced is unknown, and could be zero. Celtique Energie plans to apply for a permit to drill a test to an oil-bearing shale of the Weald Basin in 2014.

Environmental impact

In July 2014, the Scottish Government issued an Expert Scientific Panel Report on Unconventional Oil & Gas which investigated the technical, and environmental challenges of this technology. After the third reading of the Infrastructure bill in January 2015, Scotland imposed a moratorium, pending another environmental review. This prompted some comment from the original report authors.

In October 2014, the European Academies Science Advisory Council issued a review of the issues of particular relevance to the European Union. In this it stated "This EASAC analysis provides no basis for a ban on shale gas exploration or extraction using hydraulic fracturing on scientific and technical grounds". In addition, "Overall, in Europe more than 1000 horizontal wells and several thousand hydraulic fracturing jobs have been executed in recent decades. None of these operations are known to have resulted in safety or environmental problems"

A report from AMEC in December 2013 covers many of the environmental issues that would arise were the shale gas industry to become highly developed.

The Chartered Institute of Environmental Health (CIEH) and Scientists for Global Responsibility (SGR) published a report about hydraulic fracturing that was broadly negative. It referred to major shortcomings in regulatory oversight regarding local environmental and public health risks, the potential for undermining efforts to tack climate change, and the possibility that the process might cause water shortages. The report received some negative academic reviews based upon the main author being a Green Party candidate, and hydraulic fracturing protestor, and the alleged selective nature of some of the data used.

The Researching Fracking IN Europe (ReFINE) consortium from Durham University has produced a series of short video presentations taking an independent academic view on the science of shale gas production. These cover the topics 'What is Shale Gas?', 'Hydraulic Fractures, how far can they go?' 'What sized earthquakes can be caused by fracking?', 'An overview of shale gas risks', and 'Fracked or Friction?'.

The British Geological Survey are involved with environmental monitoring.

Climate change

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Hydraulic fracturing combined with horizontal drilling is likely to enable commercial extraction of shale gas in the United Kingdom. As shale gas is largely methane, a hydrocarbon fuel, the carbon dioxide it produces contributes to global warming, although less so than coal. Of more concern is leaking or fugitive emissions of unburned methane, which is a greenhouse gas. It has been argued that, in opening a new source of hydrocarbons, it may reduce the incentive and financing of renewable sources of energy. More details on the various studies that have been done on this can be found in Environmental Impact Climate change chapter

The 2008 Climate Change Act committed the UK to reducing CO₂ emissions by 50% in 2030, and by 80% by 2050. In 2014 the UK generated more than 30% of its electricity from coal, and replacing this with shale gas would be one possible solution that provides reliable on demand electricity as it has a greenhouse gas equivalent value of about half that of coal. Current National Grid energy sources can be seen on a live link.

A 2013 government-sponsored study of the effect of large-scale natural gas development in Britain concluded that emissions from shale gas could be consistent with meeting climate change targets so long as the emissions were counteracted by similar size reductions elsewhere in the world, although the authors suggest that 'without global climate policies...new fossil fuel exploitation is likely to lead to an increase in cumulative carbon emissions and the risk of climate change'.

In November 2014, the UK Energy Research Centre issued a report that stated "gas could play an important role as a ‘bridging fuel’ to a low-carbon economy, but warns that it won’t be long before gas becomes part of the problem rather than the solution". It noted that the UK imports more than half its gas, and that "gas use beginning to fall in the late 2020s and early 2030s, with any major role beyond 2035 requiring the widespread use of carbon capture and storage" It also states "Instead of banking on shale, UKERC recommends rapidly expanding investment in alternative low-carbon energy sources and investing in more gas storage, which would help protect consumers against short-term supply disruption and price rises"

Flowback fluid

Some flowback fluid can be treated and reused as hydraulic fracturing fluid. It can contain high levels of salt, and low levels of radioactive materials, known as NORMS (Naturally Occurring Radioactive Materials). The disposal and treatment of these fluids must be done under a licence from Environment Agency. Regulations regarding radioactive material and other contaminants have been tightened. Fluid disposal wells are not currently licensed in the UK by the Environment Agency. Disposal wells have been shown to be the main cause of significant earthquake risk in certain areas.

Licences were withdrawn by Cuadrilla when arrangements for disposal and treatment of contaminated water were not considered to be adequate by the Environment Agency. Waste water treatment companies have devised methods of removing 90% of NORMS allowing safe disposal of fluids under Environment Agency licence. These techniques can reduce radioactive content to less than some bottled waters. Research in the US also indicates new methods such as "microbial capacitive desalination cells" may become available.

CIWEM (The Chartered Institute of Water and Environmental Management) published a review in January 2014. It recommends shale gas extraction will be low risk as long as it is properly managed. Contamination of aquifers from mobilisation of solutes and methane is unlikely where shale plays exist at depth in the UK. The British Geological Survey believes that such contamination is unlikely to occur if shale gas exploitation is restricted to depths greater than 1500m. They also state that risk assessments need to consider all potential sources of pollution, potential pathways and receptors.

Water depletion

The DECC report Fracking UK Shale-Water states that water companies must produce, and then update every 5 years, a long term plan with contingency reserves in case of a drought. Water companies will assess the amount of water available before providing it to operators.

The Chartered Institution of Water and Environment Management have published a policy document on various water and flowback fluid issues.

DEFRA data indicates the amount of water abstracted nationally, at around 16 billion cubic metres. The DECC report shows the usage expected for hydraulic fracturing a well. It is equivalent to watering a golf course for a month. Evidence presented by the Environment Agency to the Parliamentary 'Environmental risks of fracking inquiry' indicated water usage at a peak level would be 0.1% of national usage.

Some living in drier areas, in East Kent, for example, are concerned about the effect of hydraulic fracturing in using large volumes of scarce water supplies. East Kent falls within the Environment Agency's Southern Region, the third driest region of England and Wales.

Air Pollution

There are concerns, originating in the USA that drilling could lead to pollution from hydrocarbon based chemicals. The regulations in the UK call for total fluid and gas security. meaning that in normal operations, no unburnt gases would be emitted. Venting of gas is only permitted in an emergency.

Air pollution concerns are from diesel generating plant, that will power the drilling and fracturing process, and also from truck transport. Air pollution effects are covered by EU legislation from the Air Quality Framework Directive of 1996. This requires that the effects of 12 known potentially hazardous pollutants be assessed. These include SO2, NO2, NOx PM10, and PM2.5. In an Environment Impact Assessment these risks were rated as 'not significant'.

Regarding dust 'Operators need to submit a dust management plan to the relevant environmental regulator, before they can start drilling'. Again these have been rated as 'not significant'.

Public Health England stated 'evaluated available evidence on issues including air quality, radon gas, naturally occurring radioactive materials, water contamination and waste water. They concluded that “the risks to public health from exposure to emissions from shale gas extraction are low if operations are properly run and regulated.

Flaring

Enclosed high efficiency shale gas methane burner

Open flares for well tests are not permitted in the UK. Release of unburned gas is also not permitted by the Environment Agency/SEPA. The low temperature of combustion in open flaring, and incomplete mixing of oxygen means that carbon in methane may not be burned, leading to a sooty smoke, and potential VOC/BTEX contamination. Radon gas exists in very low concentrations in shale gas and in North Sea gas, but the levels predicted fall below any level of concern. (300 microseiverts p.a.)

In exploration wells, where flow rates are expected to be 10 tonnes of gas per day, testing is licensed by the Environment Agency to 30 days, extendable to 90 days. Enclosed burners are available that will ensure low levels of light pollution, little noise, and 99+% combustion and destruction of VOCs/BTEX, at around 800 C. Well testing is used to estimate productivity of the well. In testing a production well, the test can be made by flowing into the production pipeline. This means that no gases would be lost, and flaring would not be necessary. This is known as a 'green completion'.

Seismicity (Earthquake Risk)

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System for suspending injection at seismicity of 0.5M

Following the small seismic event in the Preese Hall 1 well, and much research, the DECC issued a statement on earthquake risk.(February 2014)

Cuadrilla voluntarily suspended hydraulic fracturing in June 2011, after hydraulic fracturing a well caused two small earthquakes in Lancashire, one of magnitude M 2.3.

The ReFINE consortium has produced a presentation on the seismic risks of hydraulic fracturing.

The company's temporary halt was pending DECC guidance on the conclusions of a study being carried out by the British Geological Survey and Keele University, which concluded in April 2012 that the process posed a seismic risk minimal enough to allow it to proceed with stricter monitoring. Cuadrilla has pointed out that a number of such small-magnitude earthquakes occur naturally each month in Britain.

Cuadrilla commissioned an investigation into the seismic activity, which concluded that the tremors were probably caused by the lubrication of an existing fault plane by the unintended spread of hydraulic fracturing fluid below ground.

A 2012 report on hydraulic fracturing by the Royal Society and the Royal Academy of Engineering noted that earthquakes of magnitude M 3.0, which are more intense than the larger of the two quakes caused by Cuadrilla are: "Felt by few people at rest or in the upper floors of buildings; similar to the passing of a truck." Researchers at Durham University noted that earthquakes triggered by hydraulic fracturing are only rarely greater than M 1.

There are now six known cases of hydraulic fractured wells that are likely to have induced quakes strong enough to be felt by humans at the surface: In Canada, there have been two suspected event in Alberta (M 4.8 and M 4.4), and two in British Columbia (M 4.6 and M 4.4), one in Oklahoma, US (where several felt quakes were associated with a single fracked well); and one in Lancashire.

The M 4.8 Alberta event lead to the suspension of operations by the regulator. It was reported that there had been many events up to M 3 in 2015. In British Columbia Oil and Gas Commission reported that a 4.6-magnitude earthquake in northeastern British Columbia has been linked to the largest earthquake in the province that’s already been attributed to fracking – a 4.4-magnitude earthquake that was felt in Fort St. John and Fort Nelson in August 2014. The graphic above shows that this level of seismicity approaches levels where property damage could occur.

Mentioned on Flowback Fluid above, seismic events with the potential to initiate damage (up to M 5.6) have been associated with some water disposal wells in the US. "Thousands of disposal wells operate aseismically, four of the highest-rate wells are capable of inducing 20% of 2008 to 2013 central U.S. seismicity" Stanford Earth published video to explain the situation.

To understand the 'Moment Magnitude' method of measuring earthquake intensity, see link

Subsidence

There is no documented evidence of unconventional gas or light tight oil extraction leading to subsidence. Operations are commonly monitored with tiltmeters, and no compaction issues have been documented. Given the mechanical properties of unconventional rocks (their densities, low porosities, low Biot coefficients, and high stiffness), compaction is very unlikely to occur during hydrocarbon extraction. Subsidence has occurred in conventional gas fields very rarely, but only when the reservoir pressure of free gas was very high, and partially supporting the overlying formations. This is not the case with shale gas. One such case is the Groningen field in the Netherlands. Homeowners are to be compensated for subsidence encountered in this shallow but highly productive gasfield.

House Insurance

In an answer to questions from the 'Lets talk about Shale' initiative from the industry body, UKOOG, they have stated "According to the Association of British Insurers there is, at present, little evidence of a link between shale gas and property damage, and they are not aware of any claims where seismic activity as a result of fracking has been cited as a cause of damage. Damage as a result of earthquakes, subsidence, heave and landslip are all covered, in general, under buildings insurance. Insurers will continue to monitor the situation for the potential for fracking, or similar explorations, to cause damage."

It was reported in early 2015 that farms would not be covered by issues that may arise due to hydraulic fracturing. A clarification by the insurer indicated that this would only apply to a farmer that permitted this on their land. Surrounding farms would be covered.

Public health effects

Public Health England's Dr John Harrison, Director for Radiation, Chemical and Environmental Hazards, stated: "The currently available evidence indicates that the potential risks to public health from exposure to emissions associated with the shale gas extraction process are low if operations are properly run and regulated. Where potential risks have been identified in other countries, the reported problems are typically due to operational failure. Good on-site management and appropriate regulation of all aspects of exploratory drilling, gas capture as well as the use and storage of hydraulic fracturing fluid is essential to minimise the risks to the environment and health."

The campaign group Medact published a paper called the 'Health Impacts of Fracking' which reported health implications from fracking. This received a negative reaction from the industry group, UKOOG, as it appeared to ignore the UK fracking regulatory context. This led to a rebuttal from Medact. The content of this and other US origin studies that have been publicised in the UK were commented on by Public Health England, in the planning document from Lancashire County Council Planning Department report, published to advise councillors about upcoming fracking decisions. The quality of the research that underpinned the Medact was called into question, and use of two campaigners as authors meant that the objectivity and reliability of the report was called into question on page 311.

In addition the review of the health studies pointed to many flaws in the quoted US research, from pages 307 to 313.

Environmental impact and risk assessments

"The operator then needs to seek planning permission from the local minerals planning authority (MPA), the local planning authority (LPA) if in Scotland or DOE Planning if in Northern Ireland. These may be required as part of the planning process, The MPA/LPA/DOE will determine if an environmental impact assessment (EIA) is required."

In any event, an Environmental Risk Assessment (ERA) must be made, to identify any possible impacts to the environment. The EIAs cover a wide range of concerns, including traffic, well design, effects on wildlife, pollution potential, noise, lighting, local impacts, and well decommissioning, to name but a few. These are presented in less detail in a ' Non Technical Summary'.

Groundwater contamination

In June 2015, the US Environmental Protection Agency published its long awaited draft study into ground water pollution from hydraulic fracturing The headline was 'Assessment shows hydraulic fracturing activities have not led to widespread, systemic impacts to drinking water resources and identifies important vulnerabilities to drinking water resources' The vulnerabilities were identified as

• water withdrawals in areas with low water availability;
• hydraulic fracturing conducted directly into formations containing drinking water resources;
• inadequately cased or cemented wells resulting in below ground migration of gases and liquids;
• inadequately treated wastewater discharged into drinking water resources;
• spills of hydraulic fluids and hydraulic fracturing wastewater, including flowback and produced water.

In addition over 20 peer-reviewed articles or reports were published as part of this study

In October 2015, Yale University released a report that found no evidence that trace contamination of organic compounds in drinking water wells near the Marcellus Shale in northeastern Pennsylvania came from deep hydraulic fracturing shale horizons, underground storage tanks, well casing failures, or surface waste containment ponds.

The DECC document 'Fracking UK Shale, Water' indicates how operators must address issues water usage, and pollution potential, treatment of flowback water, together with the mitigation measures and links to well regulation requirements.

Water UK have signed a memorandum of understanding based upon a briefing paper by Water UK.

The British Geological Survey, in reviewing the US experience with hydraulic fracturing of shale formations, observed: "where the problems are genuinely attributable to shale gas operations, the problem is with poor well design and construction, rather than anything distinctive to shale gas."

The DECC reported that it had approved the use of three chemical additives in hydraulic fracturing slurries by Cuadrilla: polyacrylamide (friction reducer); hydrochloric acid, which is used at concentrations of under 1% at which concentration it is considered non-toxic; and a non-toxic biocide. In its one hydraulic fracturing job to date, Cuadrilla used only non-toxic polyacrylamide, at a concentration of 0.05%. The Environment Agency will only issue permits for what it considers non hazardous chemicals.

One potential pollution path is from leaks on the surface through spillage. The EA require chemical and fluid proof drill pads.

Methane

In March 2015, a study of methane contamination compared to distance from wells was carried out in N E Pennsylvania. With a large data set, it concluded that there was no link between the two. This study was updated when it became public that the authors were funded by Chesapeake Energy Corporation.

In September 2014,a study from the US 'Proceedings of the National Academy of Sciences' released a report that indicated that methane contamination can be correlated to distance from a well in wells that were known to leak. This however was not caused by the hydraulic fracturing process, but by poor cementation of casings.

The British Geological Survey has released national baseline methane levels, that range from negligible to high. Methane is not toxic but it does carry the risk of explosion in confined spaces, and is produced in the human gut. It is removable by the water companies by aeration, but that would be an expensive option. In the US, baseline methane measurements were not made at the start of the shale gas boom, meaning that it is difficult to prove whether a gas problem is due to drilling, and leaking wells, or is naturally occurring. This practice is now changing as this baseline study shows.

The issue of pre-existing methane is hotly debated. A study from Duke University concludes that there is a link between methane gas in groundwater, and the proximity of gas wells, in 141 readings. However this larger study (1701 readings) in the same area has shown that methane gas concentration is independent of proximity to gas wells. Baseline studies also indicate that many wells are polluted with various contaminants, independent of hydraulic fracturing. There are several other studies that have been done that do not show correlation between hydraulically fractured shale gas wells and methane or other contamination.

The exact pathway of pollution is complicated by the fact that in many areas in the US, drilling has taken place since the 1860s, and Pennsylvania for example, has an estimated 300,000 abandoned wells, many of which have no records. These can provide leakage paths in rare circumstances.

Treated mains water is the norm in the UK, and standards are required by legislation to be high. As such any methane pollution would have to be removed by the water companies by law. Private water wells are rare, around 62,000 households, out of 23.4 million households or 2.6%. In rural areas of the US private wells are common (15%), and small communities are served by investor-owned utilities, or community schemes. UK households would therefore be expected to be less at risk than those in the US.

Fracturing fluids

In September 2014, study from the US 'Proceedings of the National Academy of Sciences' released a report that indicated that there was no evidence of hydraulic fracturing chemicals being present in surface methane leaks. This showed strong evidence that methane contamination can occur in poorly cemented wells, but that any methane content is not caused by the hydraulic fracturing process. They investigated "fugitive gases in eight clusters of domestic water wells" where water quality was affected by leaking wells. They found that the "..data implicate leaks through annulus cement (four cases), production casings (three cases), and underground well failure (one case) rather than gas migration induced by hydraulic fracturing deep underground".

The US Department of Energy has conducted research involving hydraulic fracturing wells using fluid treated with a perfluorocarbon tracer. It was hydraulically fractured above a 'cap rock' that would normally limit upward growth, to within 1,800 feet (550 m) of overlying traditional permeable gas producing formations. The area is heavily faulted leading to the 'out of zone' hydraulic fracturing. The output of these wells has been monitored for traces of non native fluids from hydraulic fracturing. No trace of hydraulic fracturing fluid or other evidence of communication has yet been found between the shale well and the overlying gas formations.

The ReFINE consortium has produced a video relating to the risks of aquifer contamination through fractures.

There have been concerns raised about the potential for fractures to penetrate aquifers, polluting water supplies. Research into hydraulic fracture growth in the US indicates that:

• induced fractures in sedimentary rock only rarely penetrate upward more than a few hundred meters,
• in layered sequences of sedimentary rocks, induced fractures tend to propagate laterally within a more brittle rock unit, rather than vertically across the different layers,
• induced fractures have a predominant vertical orientation when deep, and horizontal when shallow,
• fracture growth can be monitored in real time, using tilt meters and microseismogram recordings, and can be largely confined to the target formation.
• fractures do occasionally intersect faults, but data from many wells shows that vertical growth is also limited when this occurs.
• vertical propagation of a hydraulic fracture across layers is very inefficient and it is difficult to obtain extensive vertical growth.

Examining the maximum potential vertical growth of fractures, This paper from ReFINE concludes that "The maximum upward propagation recorded for a stimulated hydraulic fracture to date is 588 m in the Barnett shale in the USA. Based upon the data presented here the probability that a stimulated hydraulic fracture extends vertically beyond 350m is approximately 1%. Very few natural hydraulic fractures pipes or simulated hydraulic fractures propagate past 500 m because layered sedimentary rocks provide natural barriers to growth."

The Royal Academy of Engineering report from 2012 indicates that the distances between potable water supplies and fractured formation in various US shale plays is large, meaning the risk of contamination is very small. No cases of pollution by this route have been identified.

Considering the conditions in the UK, the report concludes "The very unlikely event of fractures propagating all the way to overlying aquifers would provide a possible route for fracture fluids to flow. However, suitable pressure and permeability conditions would also be necessary for fluids to flow. Sufficiently high upward pressures would be required during the fracturing process and then sustained afterwards over the long term once the fracturing process had ceased. It is very difficult to conceive of how this might occur given the UK’s shale gas hydrogeological environments. Upward flow of fluids from the zone of shale gas extraction to overlying aquifers via fractures in the intervening strata is highly unlikely".

For deep formation water to pollute an aquifer it must first have a pathway to follow, and also have a driving mechanism to force it upwards. The fractures could possibly provide a pathway, but to rise the water would have to be buoyant. Oil in the UK, with a density less than 1 g/cc needs to be pumped out. Any formation water will usually have salts, heavy metals, and small amounts of radioactive materials dissolved in it. This means that its density will be greater than 1 g/cc, and as such there is no driving mechanism to pollute an aquifer, even if a pathway existed, as the water cannot rise.

If there were a pressure profile that meant fluids could migrate upwards, the low permeability of formations mean that pollution times would be geological in scale.

Monitoring of fracture growth

Microseismic monitoring techniques, using very sensitive microphones and tilt meters can monitor the growth of fractures in the target formation in real time. This can be done using a surface array, or, if there is a nearby offset well, using downhole microphones. This means that the engineers can modify the pump rate based upon the growth of the fractures, and stop pumping if there is evidence of vertical migration into faults. This technology is available from many big oilfield service companies.

Regulation

The Government commissioned a report to identify the problems and advise regulatory agencies. Jointly published by the Royal Society and the Royal Academy of Engineering, under the chairmanship of Professor Robert Mair, the report included recommendations on groundwater contamination, well integrity, seismic risk, gas leakage, water usage and disposal, management of environmental risk, implementation of best practice, and various management and regulatory issues. According to Professor Mair,"well integrity is of key importance but the most common areas of concern, such as the causation of earthquakes with any significant impact or fractures reaching and contaminating drinking water, were very low risk" but the report stated adequate regulations must be put in place. The RAE report stated, "Many claims of contaminated water wells due to shale gas extraction have been made. None has shown evidence of chemicals found in hydraulic fracturing fluids". This report lead to a Government paper that outlined the requirements of the regulatory framework.

There are separate regulatory authorities in Scotland, Wales and Ireland

There are a variety of Government Agencies involved in regulation. The Department of Energy and Climate Change, DECC, is one of the key Departments to grant permission. It is required that chemicals used must be available for public examination "Chemicals used in drilling and hydraulic fracturing fluids are assessed for hazards on a case-by-case basis for each well by the appropriate environmental regulator (EA, NRW or SEPA). Operators must declare the full details of the chemicals to the regulator and will publish a brief description of the chemical’s purpose and any hazards it may pose to the environment". The Environment Agency have issued a guidance note to well operators, detailing the steps required for drilling permission to be granted.

Another regulator on the engineering issues is the Health and Safety Executive. Examination of a brief of their regulations show that well design must be approved by the HSE and then sent to an independent Well Examiner. Under current regulation, the 'independent' Well Examiner can be an employee of the operating company, as identified in the RAE report.

In the event of a poor cementation remediation must involve expert opinion of the Well Examiner. Poor cementation has been identified in the RAE report as one of the main pollution paths and sources of surface gas leaks in the US.

The British Geological Survey (BGS) also have to be consulted.

Local Councils and parish councils also have some regulatory powers, with regard to planning permission. These can be overturned on appeal.

The Minerals Planning Authority (MPA) will determine if an environmental impact assessment (EIA) is required. This would be funded by the operating company.

The regulatory process has been set out in publications and guidelines on techniques and practices from the industry body, UKOOG. There are also requirements for community engagement.The industry currently has to comply with 17 European Directives, has to apply for up to nine separate environmental permits and has to reach binding agreements on noise, hours of operation and other local social issues. In compliance with the industry’s engagement charter, each operator engages with the public at six points during the pre-consultation, planning and permitting stag.

However, the European Commission's impact assessment of potential new regulations on fracking concluded that the current situation "is not effective in addressing environmental risks and impacts, nor in providing legal clarity / certainty nor allaying public concerns", and that a new Directive setting specific requirements for fracking would be the most beneficial option.

The regulation of fracking in the UK has been criticised by the chemicals policy charity CHEM Trust, who argue that it is not sufficiently protective. They also raise concerns about reducing resources for the regulators of fracking, like the Environment Agency. The UK Fracking Industry trade association OKOOG challenged the CHEM Trust analysis, and CHEM Trust then responded to the issues raised by UKOOG.

Chemicals permitted for hydraulic fracturing in the UK

Only 'non-hazardous' chemicals are permitted for hydraulic fracturing fluids in the UK by the Environment Agency (EA). The nature (though not the concentration) of these chemicals must be made available to the public.

Increasingly, food additive based chemicals are becoming available, replacing hazardous chemicals that have been used in the past.

The European wide Groundwater Directive is European legislation that states. In order to protect the environment as a whole, and human health in particular, detrimental concentrations of harmful pollutants in groundwater must be avoided, prevented or reduced.

The Environment Agency regulations state Groundwater’ means all water that is below the surface of the ground in the saturation zone and in contact with the groundwater or subsoil (EPR, Regulation 2(1)).

‘Aquifer’ means a subsurface layer or layers of rock or other geological strata of sufficient permeability to allow either a significant flow of groundwater or the abstraction of significant quantities of groundwater (WFD Article 2.11).

Under EPR Schedule 22, paragraph 6 we must take all necessary measures to: (a) prevent the input of any hazardous substance to groundwater; and (b) limit the input of non-hazardous pollutants to groundwater so as to ensure that such inputs do not cause pollution of groundwater. The Environment Agency would not authorise the use of a hazardous substance for an activity, including hydraulic fracturing.

The pollutants the Environment Agency are concerned with for groundwater are: ‘Hazardous substances’, which are substances or groups of substances that are toxic, persistent and liable to bioaccumulate, and other substances or groups of substances that give rise to an equivalent level of concern (EPR Schedule 22, paragraph 4).

Any non-hazardous pollutants, which is ‘any pollutant other than a hazardous substance (EPR, Schedule 22, paragraph 5).

Substances on List I of the binding Groundwater Directive (80/68/EEC) are taken to be hazardous substances

The Environment Agency list of chemicals does not contain all of those that may be proposed in hydraulic fracturing. The regulations above indicate that authorisation would be decided on a case by case basis, using the above protocols.

In the Preese Hall 1 well, the chemical concentration was 0.05%. However, when millions of gallons of water are being used, the amount of chemicals per fracturing operation could be large. For example, a 4 million imperial gallons (18,000 m³) hydraulic fracturing operation would use at 1%, 180 tonnes. At 0.05% this would be 9 tonnes. The main additive is polyacrylamide, the purpose of which is to reduce the viscosity of the water, to allow faster pumping. Additional chemicals that have been permitted are highly dilute hydrochloric acid, a sodium tracer salt and glutaraldehyde, which is used as a biocide in very small quantities, to kill bacteria that could damage a well. This rapidly breaks down into non toxic materials. It is not necessary to use this if domestic water, treated with chlorine, is supplied, as this will be bacteria free anyway. Increasingly UV treatment will replace chemicals for treatment.

Although some of the chemicals used in hydraulic fracturing fluids such as hydrochloric acid may be classified as toxic, corrosive or irritant, they are non-toxic at the concentrations used.

Although hydraulic fracturing was not proposed in a well at Balcombe, the EA permitted one requested chemical oxirane, while not permitting the use of antimony trioxide which is suspected as being carcinogenic.

Differences between the US and UK

Natural gas price comparison, UK, US and Japan

In the United States, regulation of oil and gas drilling and production is largely left to the states, and differs from state to state. In 2005 in the US Congress, at the behest of then Vice President Dick Cheney, a former CEO of Halliburton, exempted hydraulic fracturing from the underground injection regulations of the Safe Drinking Water Act. This meant that any chemical, including toxic and carcinogenic materials were permitted, and public disclosure of these was not required.

There are also differences in fluid security that mean that open fluid storage is not permitted in the EU or the UK. Venting of unburnt gases is also not permitted, except in an emergency.

Paying for regulation

The costs of inspections by the Environment Agency, and the HSE can be reclaimed from operators by those agencies.

The HSE and EA have an agreement concerning the inspection of critical processes.

The Infrastructure Act 2015

In February, the Infrastructure Act 2015 received royal assent. The bill covered many aspects of fracking, and permits fracking under homes, without consent. The legislation is limited to the petroleum and geothermal industries.

This also included clauses on maximizing economic recovery of UK petroleum on meeting climate change requirements and changed the definition of hydraulic fracturing to more than 1000m of fluid per stage ot more than 10,000m in total. In addition conditions were attached that mean no fracking can take place at a depth shallower than 1000m, and that soil and air monitoring must be put in place. 'The associated hydraulic fracturing will not take place within protected groundwater source areas' statement does not define the category of groundwater protection zone.

Fracking under National Parks

The Durham Energy Institute has produced an evaluation of the potential impact and likelihood of drilling in environmentally sensitive areas.

Geothermal energy

The Eden Project in Cornwall is in the process of drilling and hydraulically fracturing two geothermal wells for utilisation of geothermal energy as a source for a geothermal power station.

The 'Fracking' debate

An Anti Fracking protest at a limestone oil well with no permission to 'frack'.

This section has information about concerns that fall under the general public conception of fracking. This term is commonly used to mean any form of hydrocarbon extraction, and is mixed in with the Climate Change debate. The photo shows an 'anti frack' rally at Balcombe, which is an oil well in limestone that had no permission to hydraulically fracture the formation. Others protest using shale gas techniques as a focus, at proposed coalbed methane sites.

Anti-fracking protesters say that there are various problems associated with the process including pressure on local transport infrastructure, air and water pollution, the amounts of water used, and potential economic damage to agricultural, food production and tourism industries.

Land usage

Directional drilling allows a large hydrocarbon reservoir to be accessed using a single well pad, such as in Europe's biggest onshore oilfield, Wytch Farm. Vertically drilled fields, like the Jonah Gas field, will have a larger surface impact, but would not be likely in the UK due to planning restrictions. Likely well spacing visualised by the December 2013 DECC Strategic Environmental Assessment report indicated that well pad spacings of 5 km were likely in crowded areas, with up to 3 hectares per well pad. Each pad could have 24 separate wells. This amounts to 0.16% of land area.

Well leak concerns

In March 2014, ReFINE published a report that investigated well leak concerns, involving UK's producing, suspended, old, abandoned, and 'orphaned' wells. It included a large number of data sets, from around the world, including some very old well data. There are issues of 'well barrier', where an internal leak is found, that does not leak to the environment, and 'well integrity' where external leaking/venting is an issue. The data provided often puts the two data sets together. In the REFINE abstract, the percentage of wells that have had some form of well barrier or integrity failure is highly variable (1.9% to 75%). Looking at the most recent results In a separate study of 3533 Pennsylvanian wells monitored between 2008 and 2011, there were 85 examples of cement or casing failures, 4 blowouts and 2 examples of gas venting. A September 2013 paper states True well integrity failure rates are two to three orders of magnitude lower than single barrier failure. Another paper from 2012 indicates that the bulk of the environment code violations in recent activity in Pennsylvania are nothing to do with well leaks.

The response from UKOOG welcomed the ReFINE report, stating that well leaks in the UK were little problem, and contrasted the small number of orphan wells with the estimated 250,000 abandoned mines.

It is commonly believed that '6% of wells leak immediately, 50% of wells leak after some time and all wells will leak eventually'. This is not an issue specific to hydraulic fracturing, it is a concern with every well that is drilled. This originates from a document that sells solutions for this problem to oil and gas companies. This often relates to 'SCP', or Sustained Casing Pressure This is a 'well barrier' issue, but could also include casing 'integrity' (external) leaks. Data from DECC has been released concerning this and of the approx 2000 onshore wells, and approx 6500 offshore well, the number of current recorded leaks is zero, although there was a need for two well integrity repairs. The ReFINE report does also indicate that there is no meaningful data on the bulk of the land based wells, and that only the 143 producing wells have been examined. Regulation calls for baseline monitoring to determine if any leak issues are related to the drilled well.

A research paper, from 2009 indicates Low cement top or exposed casing was found to be the most important indicator for sustained casing vent flow (SCVF)or gas migration (GM)SCVF/GM. The effect of low or poor cement was evaluated on the basis of the location of the SCVF/GM compared to the cement top. The vast majority of SCVF/GM originates from formations not isolated by cement. The current regulations from the HSE are designed to mitigate these concerns, and seal wells back to the surface.

Concern has been raised about some wells drilled before the latest guidelines that do have potential leak paths. An internal memo shows on page 3 that there is no cement from 1200 feet to the surface aquifer, and as such there is a potential leak path. If the casing were to leak due to corrosion or other reason, there would be a leak path from deep salty formations into the aquifer. In addition the aquifer is only protected by one layer of (uncemented) casing.

Information from the US Groundwater Protection Council shows that there is a failure rate of around 1 every 3500 wells, or 0.03%.

If a well were to leak, workover operations can usually fix leaks, by, for instance, perforating the casing above and below a poorly cemented zone, and 'squeezing' cement behind the pipe. The cement is drilled out and a pressure test is performed until pressure integrity is good.

Preese Hall # 1 well

In the Preese Hall 1 well, the UK's only hydraulically fractured shale gas well (to November 2014), drilled by Cuadrilla Resources, there was poor cementation in the horizontal production zone only. Cement is pumped up the outside of the casing and if the casing is not well centralised, the cement may not seal completely around the casing. Poor cementation, if confined to the production zone, does not create a leaking well, as long as there is good cementation above it, through the cap rocks, or 'regional seals'. The casing in the production zone will be perforated anyway, to allow hydraulic fracturing fluid to flow out of the borehole and into the target formation. The only problem posed by poor cementation in the production zone is that it may reduce the effectiveness of the hydraulic fracturing. The borehole is hydraulically fractured in stages, typically several hundred feet at a time, so if the casing is not well cemented, then the hydraulic fracturing fluid may dissipate into other parts of the productive formation. That may compromise the production of the well, but would not pose a leak or safety issue.

The role of pressure differential in a well during hydraulic fracturing is sometimes mischaracterized. When a well is hydraulically fractured, or when any injection is carried out, this is done through a packer (seal), and is done through the drill pipe or tubing. Fluids are circulated down the tubing, to below the point where the packer is sealed against the production casing. Pressure is then be applied only that part of the casing below the packer. The rest of the well casing will not experience any increase in pressure due to the sealing of the packer. The surface casings do not experience the great pressures experienced at the production zone. This means the stresses on a surface casing are no greater than on a normal oil or gas well. Smaller diameter pipes can sustain much larger pressures than large diameter pipes.

Use of radioactive sources

Main article: Uses of radioactivity in oil and gas wells § Use of radioactive sources for logging

There have been some public concerns about use of radioactive sources in wells. The difference between radiation dose and Radioactive contamination seems to be poorly understood. Well logs involving radioactive sources are a legal requirement.

Political issues

Hydraulic fracturing has brought with it various challenges for Britain’s political parties. That is particularly the case for the Conservative Party, where there are tensions between the aspirations of the leadership – who tend to view shale gas in terms of economic benefit, energy independence, and a means of reducing carbon emissions – and the priorities of many of its supporters who are hostile to the process, especially those who live in areas likely to be explored for shale gas.

The Liberal Democrats, in 2013 in a coalition government with the Conservative government which strongly supported hydraulic fracturing, began taking a position downplaying prospects for a "shale gas revolution", issuing several position papers on climate change which minimized the role of shale gas in favour of renewables. The Labour Party has been more reticent, but MPs have indicated they are receptive to hydraulic fracturing if environmental safeguards and an appropriate regulatory regime are in place. By contrast, UKIP is enthusiastic about shale gas, a stance that is partly derived from its hostility to wind farms. The UK Green Party`s energy policy EN264 states that: "We will halt the development of coal-bed methane, shale gas and similar hydrocarbon exploitation since it is not needed to meet UK energy demands, is environmentally destructive, and will lead to increasing GHG emissions".

As of 2013 the government was solidly behind development of the fossil fuel shale gas industry and was offering to give shale gas companies favourable tax treatment for the unconventional energy source. Also they stated they would turn 100% of business tax proceeds over to local councils instead of the usual 50% which has been seen as controversial in some parts of the media. Green Party leader Natalie Bennett said of the government's proposal to turn the business taxes gained from hydraulic fracturing over to the local councils: "It looks like the government is bribing local councils and it shows how desperate it is to get fracking accepted locally."

The House of Lords report "The Economic Impact on UK Energy Policy of Shale Gas and Oil" from the Economic Affairs Committee was published in May 2014. It took evidence on a wide variety of subjects from a wide variety of sources. It concludes that shale gas exploration and development should go ahead urgently, and that the regulatory regime was complex, and a hindrance to growth.

In May 2014, the prospect of drilling under peoples homes was put out for consultation and the resulting report in October 2014 indicated that 99% of 40,000 responses were opposed to this. The Infrastructure bill, which became law in February 2015, included an amendment that this was to be permitted. The National Farmers Union issued this statement that indicated concerns with property prices, long term environmental issues and payment for access in line with other industries.

The chemical firm Ineos has proposed that they would pay 6% of income in payments for local people, farmers, and landowners. Ineos chairman Jim Ratcliffe said "Giving 6% of revenues to those living above Britain's shale gas developments means the rewards will be fairly shared by everyone." Friends of the Earth said this was a "transparent attempt to bribe communities"

Effect on house prices

The possible effect of house prices due to hydraulic fracturing is a highly emotive one due to large amount of capital invested by the owners.

In August 2014, a report called 'Shale Gas:Rural Economic Impacts' was published by the UK Government, in response to a Freedom of Information request, from Greenpeace. It was due for publication in March 2014. It was notable as large parts of this had been redacted, leading to criticism about the transparency of information being provided. In certain areas of the US house prices have reduced in areas where hydraulic fracturing is taking place, and whether this will affect the market in the UK remains to be seen. The effect was mainly reported to be with houses that used well water, whereas houses that had piped water saw a slight increase.

Conflicts of interest

There have been a number of concerns raised regarding conflicts of interest between policy makers and financial links to hydraulic fracturing, notably Lord Browne of Cuadrilla - The former BP boss is chairman of Cuadrilla, which is exploring for shale gas in Lancashire and West Sussex. He is lead "non-executive" across Government. Baroness Hogg - The non-executive for the Treasury sits on the board of BG Group, which has significant shale gas assets in the United States. Sam Laidlaw - The non-executive to the Transport Department is also chief executive of British Gas owner Centrica, which recently bought a 25 per cent stake in Cuadrilla's most promising shale gas prospect. Ben Moxham - A former executive at BP when Lord Browne was at the helm, he followed the peer to Riverstone Holdings, which owns 42 per cent of Cuadrilla. Moxham was energy adviser at No 10 but quit in May (year?). Lord Howell - George Osborne's father-in-law is also president of the British Institute of Economics, whose backers include BP and BG Group. House of Lord's Select Committee on Economic Affairs potential conflicts of interest with regards to hydraulic fracturing. Baron Hollick: Has shares in Samson resources a US company with shale gas investments. Lord Skidelsky: invested in Janus Capital who hold stakes in oil and gas firms Lord Mcfall: Held investments in FTI consulting, fracking industry advisers Baroness Noakes: had shares in at least 3 firms with interests in shale gas. Lord MacGregor or John MacGregor as he was previously known is the current Chairman of ‘The British Energy Pension Fund Trustees and Chairman, Eggborough Power Ltd Pension Fund Trustees, both now part of EDF Energy. CPRE Northumberland's Chairman David Montag-Smith is also chairman of the board of directors of Rathlin Energy Ltd who are exploring Yorkshire for shale gas.

Opposition

Balcombe anti-fracking protest - July 2013

There are a number of anti-fracking groups, which range from the nationwide Frack Off which was engaged in the Balcombe drilling protest, to local ones such as Residents Action on Fylde Fracking, Ribble Estuary Against Fracking, NO Fracking in Sussex, Frack Free Fernhurst and The Vale Says No! The Environmental Group Greenpeace publish an online 'live' fracking report Friends of the Earth are also against Fracking.

In the UK and Europe, hydrocarbons are government property, so local residents have little to gain from oil and gas drilling; the situation is different in the US, where landowners commonly also own the oil and gas, and so negotiate lease bonuses and production royalties from the oil companies.

In September 2011, with licences having been granted to two energy companies for exploratory drilling in Somerset, Bath and North East Somerset Council voiced concern that, should the test drilling yield a significant find of shale gas, any subsequent hydraulic fracturing could contaminate Bath's famous hot springs. Similar worries about future hydraulic fracturing have been aired in a number of other places, including the Vale of Glamorgan and Woodnesborough, Kent. Industry assurances about its forthcoming plans were tarnished in January 2012, though, when Cuadrilla Resources came under fire for its categorical denials of plans of hydraulic fracturing near Balcombe after documents from parent company AJ Lucas materialised appearing to indicate the complete opposite.

In March 2014, a group of conservation charities including the RSPB and the National Trust released a report containing a 10-point plan for increased regulation, and highlighting concerns about groundwater pollution, industrialization of the countryside, Environmental Impact Assessments, and hydraulic fracturing inside National Parks. The response from UKOOG, the representative body for the UK onshore oil and gas industry pointed at 'critical inaccuracies', and stated that the regulation called for was largely in place.

Wales

In October 2011 the campaign to prohibit Coastal Oil and Gas from test drilling at the Llandow Industrial Estate, in the Vale of Glamorgan, met with initial success after local councillors unanimously refused the company's plans, though Coastal immediately indicated it would appeal. Residents feared that successful exploration would be the prelude for hydraulic fracturing. The basis of the Council's decision was a letter from Welsh Water stating that there was "a very small risk" of contamination of its reserve groundwater sites from exploratory drilling. The rejection came despite the Council being told that, strictly from a planning point of view, there were no "reasonable or sustainable grounds" to refuse, and despite the drilling application containing no explicit mention of hydraulic fracturing. The company had additionally claimed that, since the "gas shales in the Vale are not as thick as elsewhere", any discoveries would be "very unlikely" to require hydraulic fracturing for extraction.

Coastal Oil and Gas decided to appeal to the Welsh Government, rather than undertake legal action against the local authority, and a public enquiry began in May 2012. Coastal's chances of success at the enquiry were boosted by Kent County Council approval of the company's near-identical plans for preliminary drilling in Woodnesborough, and were increased to near certainty after Welsh Water effectively retracted its previous risk assessment.

Industry response

In arguing its case, Cuadrilla contrasts its approach with the one taken in the United States, claiming that only three chemicals—a polyacrylamide lubricant commonly found in cosmetics, hydrochloric acid, and a biocide used to purify drinking water—will be used in the UK, compared with the hundreds that can be used across the Atlantic; that it has invested in more expensive, better equipment than that used by companies operating in the US; that its wells have three layers of pipe casing to line the wells, whereas many American ones only have two; that the barrier between the gas escaping up the pipe and ground water is thicker; that cement will be returned to the surface, blocking identified leak paths; and that drilling fluids will be collected in closed steel tanks, rather than in lined earthen pits, as often happens in the States. According to Cuadrilla's communication advisor, "Gasland (the US documentary about shale gas) really changed everything. . . . Before that, shale gas was not seen as routinely controversial."

Public opinion

In September 2014, Nottingham University published a report on public attitudes, showing a slight reversal of the negative views that were held on hydraulic fracturing. A poll for the Guardian reported that 70% of people were against hydraulic fracturing in National Parks. When the caveat 'fracking with proper regulation' was applied support for hydraulic fracturing rose to 57%, with 26% opposed.

In May 2014, an ongoing survey by the University of Nottingham indicated that support for hydraulic fracturing fell below 50% for the first time. The publicity surrounding the Balcombe protest was considered an important factor.

A January 2014 Guardian poll found that a majority support shale gas extraction, but by a somewhat narrower margin than previously. To the question "Should shale gas extraction be allowed?" 53% said yes (down from 58% in July 2012), and 27% answered no (up from 19% in July 2012).

A poll conducted by Opinium/Observer in August 2013 showed that while men in the UK were evenly divided about fracking taking place in their area, women were strongly against it; the population as a whole preferred renewables such as wind farms.

An ICM poll in August 2013 found that public opinion in the UK was in favour of hydraulic fracturing in general, by 44% in favour to 30% opposed. However, when asked if they favoured hydraulic fracturing in their own area, the public split evenly, 40% in favour to 40% against. Support for fracking was stronger among men, older people, and conservatives.

See also

• Cost of electricity by source
• Oil and gas industry in the United Kingdom
• Refracktion, an environmental organisation

External links

• Industry guide to regulation process
• Environment Agency requirements for 'Non Hazardous' chemicals
• Guide to the regulation of a well by the Health and Safety Executive
• Illustration of fracking
• DECC's FAQs on shale gas
• British Geological Survey's information about shale gas
• Guardian coverage of shale gas and fracking
• Cuadrilla Resources
• BBC, Fracking: Untangling fact from fiction
• Fluid proof drill pads video by Cuadrilla

UK Government Publications

• Planning Permission and Communities.
• 'Water'
• 'Facts about Fracking'
• 'Climate Change'
• 'AirQuality'
• 'Regulation'
• 'Design to Decommissioning'
• 'Earthquake risk'