Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Shale gas extraction in the UK: a review of hydraulic fracturing


Published on

A 76-page report issued by the UK Royal Academy of Engineering and the UK Royal Society. The report encourages the UK to expand fracking in that country and says when regulated propertly, fracking is safe.

Shale gas extraction in the UK: a review of hydraulic fracturing

  1. 1. Shale gasextractionin the UK:a review ofhydraulicfracturingJune 2012
  2. 2. Shale gas extraction in the UK: a review of hydraulic fracturing Issued: June 2012 DES2597 © The Royal Society and The Royal Academy of Engineering 2012 The text of this work is licensed under Creative Commons Attribution-NonCommercial-ShareAlike CC BY-NC-SA. The license is available at: Images are not covered by this license and requests to use them should be submitted to: Requests to reproduce all or part of this document should be submitted to: The Royal Society The Royal Academy of Engineering Science Policy Centre 3 Carlton House Terrace 6 – 9 Carlton House Terrace London SW1Y 5DG London SW1Y 5AG T +44 20 7766 0600 T +44 20 7451 2500 W E W This document can be viewed online at: and Shale gas extraction in the UK: a review of hydraulic fracturing
  3. 3. ContentsSummary ........................................................4 Chapter 6 – Risk management ....................48 6.1 The UK’s goal based approach toRecommendations ..........................................6 regulation ......................................................48 6.2 Collecting data to improve riskTerms of reference .........................................8 assessments ................................................. 49 6.3 Environmental risk assessments ................... 51Chapter 1 – Introduction.................................91.1 Hydraulic fracturing.........................................9 Chapter 7 – Regulating shale gas .................531.2 Stages of shale gas extraction ...................... 10 7.1 Conditions of Petroleum Exploration and1.3 The global policy context .............................. 10 Development Licences..................................531.4 Environmental concerns in the USA ............. 11 7.2 Conditions of local planning permission.......541.5 Environmental concerns in Europe ............... 14 7.3 Notification of well construction and the1.6 Moratoria ...................................................... 15 well examination scheme..............................541.7 Concerns about seismicity ............................ 15 7.4 Conditions of environmental permits............551.8 The UK policy context ................................... 17 7.5 Regulating production activities on a nationwide scale ...........................................55Chapter 2 – Surface operations .................... 192.1 Fracturing fluid .............................................. 19 Chapter 8 – Research on shale gas ..............572.2 Water requirements .....................................20 8.1 Uncertainties affecting small scale2.3 Managing wastewaters .................................20 exploratory activities .....................................572.4 Disposal of wastewaters ...............................21 8.2 Uncertainties affecting large scale2.5 Disposal of solid wastes ...............................22 production activities ......................................572.6 Managing methane and other emissions ....22 8.3 Funding research on shale gas .....................58Chapter 3 – Well integrity ............................243.1 Preventing well failure ...................................25 References ....................................................603.2 Improving the well examination scheme .....263.3 Detecting well failure ....................................27 Acronyms .....................................................66Chapter 4 – Fracture propagation ................. 31 Glossary ........................................................684.1 Monitoring fractures .....................................314.2 Constraining fracture growth ........................32 Appendix 1 – Working Group .......................704.3 Hydraulic fracturing below aquifers ..............34 Appendix 2 – Evidence gathering .................72Chapter 5 – Induced seismicity ....................405.1 Natural seismicity ..........................................40 Appendix 3 – Review Panel ..........................755.2 Seismicity induced by coal mining ...............405.3 Seismicity induced by hydraulic fracturing... 415.4 Factors affecting seismicity induced by hydraulic fracturing .......................................425.5 Mitigating induced seismicity .......................435.6 Damage to well integrity ...............................455.7 Seismicity induced by disposal.....................455.8 Regulating induced seismicity ......................46 Shale gas extraction in the UK: a review of hydraulic fracturing 3
  4. 4. SUMMARY Summary The health, safety and environmental risks associated Concerns have also been raised about seismicity with hydraulic fracturing (often termed ‘fracking’) induced by hydraulic fracturing. Natural seismicity as a means to extract shale gas can be managed in the UK is low by world standards. On average, effectively in the UK as long as operational best the UK experiences seismicity of magnitude 5 ML practices are implemented and enforced through (felt by everyone nearby) every twenty years, and regulation. Hydraulic fracturing is an established of magnitude 4 ML (felt by many people) every technology that has been used in the oil and gas three to four years. The UK has lived with seismicity industries for many decades. The UK has 60 years’ induced by coal mining activities or the settlement of experience of regulating onshore and offshore oil abandoned mines for a long time. British Geological and gas industries. Survey records indicate that coal mining-related seismicity is generally of smaller magnitude than Concerns have been raised about the risk of fractures natural seismicity and no larger than 4 ML. Seismicity propagating from shale formations to reach overlying induced by hydraulic fracturing is likely to be of even aquifers. The available evidence indicates that this smaller magnitude. There is an emerging consensus risk is very low provided that shale gas extraction that the magnitude of seismicity induced by hydraulic takes place at depths of many hundreds of metres or fracturing would be no greater than 3 ML (felt by several kilometres. Geological mechanisms constrain few people and resulting in negligible, if any, surface the distances that fractures may propagate vertically. impacts). Recent seismicity induced by hydraulic Even if communication with overlying aquifers were fracturing in the UK was of magnitude 2.3 ML and possible, suitable pressure conditions would still be 1.5 ML (unlikely to be felt by anyone). The risk of PGEGUUCT[ HQT EQPVCOKPCPVU VQ ƃQY VJTQWIJ HTCEVWTGU seismicity induced by hydraulic fracturing can be More likely causes of possible environmental TGFWEGF D[ VTCHƂE NKIJV OQPKVQTKPI U[UVGOU VJCV WUG contamination include faulty wells, and leaks and real-time seismic monitoring so that operators can spills associated with surface operations. Neither respond promptly. cause is unique to shale gas. Both are common to all oil and gas wells and extractive activities. Monitoring should be carried out before, during and after shale gas operations to inform risk assessments. Ensuring well integrity must remain the highest Methane and other contaminants in groundwater priority to prevent contamination. The probability of should be monitored, as well as potential leakages of well failure is low for a single well if it is designed, methane and other gases into the atmosphere. The constructed and abandoned according to best geology of sites should be characterised and faults practice. The UK’s well examination scheme was KFGPVKƂGF /QPKVQTKPI FCVC UJQWNF DG UWDOKVVGF VQ set up so that the design of offshore wells could be the UK’s regulators to manage potential hazards, reviewed by independent, specialist experts. This inform local planning processes and address wider UEJGOG OWUV DG OCFG ƂV HQT RWTRQUG HQT QPUJQTG concerns. Monitoring of any potential leaks of activities. Effects of unforeseen leaks or spills methane would provide data to assess the carbon can be mitigated by proper site construction and footprint of shale gas extraction. impermeable lining. Disclosure of the constituents QH HTCEVWTKPI ƃWKF KU CNTGCF[ OCPFCVQT[ KP VJG 7- Ensuring, where possible, that chemical additives are non-hazardous would help to mitigate the impact of any leak or spill.4 Shale gas extraction in the UK: a review of hydraulic fracturing
  5. 5. SUMMARYThe UK’s goal based approach to regulation is to more concentrated during waste commended, requiring operators to identify and NORM management is not unique to shale gasassess risks in a way that fosters innovation and GZVTCEVKQP 014/ KU RTGUGPV KP YCUVG ƃWKFU HTQOcontinuous improvement in risk management. The the conventional oil and gas industries, as wellUK’s health and safety regulators and environmental as in mining industries, such as coal and potash.regulators should work together to develop Much work has been carried out globally onIWKFGNKPGU URGEKƂE VQ UJCNG ICU GZVTCEVKQP VQ JGNR monitoring levels of radioactivity and handlingoperators carry out goal based risk assessments NORMs in these industries.according to the principle of reducing risks to AsLow As Reasonably Practicable (ALARP). Risk Shale gas extraction in the UK is presently at a veryassessments should be submitted to the regulators small scale, involving only exploratory activities.for scrutiny and then enforced through monitoring Uncertainties can be addressed through robustactivities and inspections. It is mandatory for OQPKVQTKPI U[UVGOU CPF TGUGCTEJ CEVKXKVKGU KFGPVKƂGFoperators to report well failures, as well as other in this report. There is greater uncertainty aboutaccidents and incidents to the UK’s regulators. the scale of production activities should a futureMechanisms should be put in place so that reports shale gas industry develop nationwide. Attentioncan also be shared between operators to improve must be paid to the way in which risks scale up.risk assessments and promote best practices across Co-ordination of the numerous bodies withthe industry. regulatory responsibilities for shale gas extraction must be maintained. Regulatory capacity mayAn Environmental Risk Assessment (ERA) should need to be mandatory for all shale gas operations. Risksshould be assessed across the entire lifecycle of Decisions are soon to be made about shale gasshale gas extraction, including risks associated with extraction continuing in the UK. The next round ofthe disposal of wastes and abandonment of wells. issuing Petroleum Exploration and DevelopmentSeismic risks should also feature as part of the ERA. Licences is also pending. This report has not attempted to determine whether shale gas extractionWater requirements can be managed through should go ahead. This remains the responsibilityintegrated operational practices, such as recycling of the Government. This report has analysed theand reusing wastewaters where possible. Options technical aspects of the environmental, health andfor disposing of wastes should be planned from safety risks associated with shale gas extraction tothe outset. Should any onshore disposal wells be inform decision making. Neither risks associated withnecessary in the UK, their construction, regulation the subsequent use of shale gas nor climate risksand siting would need further consideration. JCXG DGGP CPCN[UGF GEKUKQP OCMKPI YQWNF DGPGƂV from research into the climate risks associated withWastewaters may contain Naturally Occurring both the extraction and use of shale gas. FurtherRadioactive Material (NORM) that are present in DGPGƂV YQWNF CNUQ DG FGTKXGF HTQO TGUGCTEJ KPVQ VJGUJCNGU CV NGXGNU UKIPKƂECPVN[ NQYGT VJCP UCHG NKOKVU public acceptability of all these risks in the contextof exposure. These wastewaters are in need of of the UK’s energy, climate and economic policies.careful management should NORM become Shale gas extraction in the UK: a review of hydraulic fracturing 5
  6. 6. SUMMARY Recommendations Recommendation 1 Recommendation 3 To detect groundwater contamination: To mitigate induced seismicity: r The UK’s environmental regulators should work r BGS or other appropriate bodies should carry with the British Geological Survey (BGS) to carry out national surveys to characterise stresses and out comprehensive national baseline surveys of identify faults in UK shales. Operators should carry methane and other contaminants in groundwater. out site-specific surveys to characterise and identify local stresses and faults. r Operators should carry out site-specific monitoring of methane and other contaminants r Seismicity should be monitored before, during in groundwater before, during and after shale gas and after hydraulic fracturing. operations. r Traffic light monitoring systems should be r Arrangements for monitoring abandoned wells implemented and data fed back to well injection need to be developed. Funding of this monitoring operations so that action can be taken to mitigate and any remediation work needs further any induced seismicity. consideration. r DECC should consider how induced seismicity is r The data collected by operators should be to be regulated. Operators should share data with submitted to the appropriate regulator. DECC and BGS to establish a national database of shale stress and fault properties so that suitable Recommendation 2 well locations can be identified. To ensure well integrity: Recommendation 4 r Guidelines should be clarified to ensure the To detect potential leakages of gas: independence of the well examiner from the operator. r Operators should monitor potential leakages of methane or other emissions to the atmosphere r Well designs should be reviewed by the before, during and after shale gas operations. well examiner from both a health and safety perspective and an environmental perspective. r The data collected by operators should be submitted to the appropriate regulator. These r The well examiner should carry out onsite data could inform wider assessments, such as inspections as appropriate to ensure that wells the carbon footprint of shale gas extraction. are constructed according to the agreed design. Recommendation 5 r Operators should ensure that well integrity tests Water should be managed in an integrated way: are carried out as appropriate, such as pressure r Techniques and operational practices should be tests and cement bond logs. implemented to minimise water use and avoid abstracting water from supplies that may be r The results of well tests and the reports of under stress. well examinations should be submitted to the Department of Energy and Climate r Wastewater should be recycled and reused Change (DECC). where possible. r Options for treating and disposing of wastes should be planned from the outset. The construction, regulation and siting of any future onshore disposal wells need further investigation.6 Shale gas extraction in the UK: a review of hydraulic fracturing
  7. 7. SUMMARYRecommendation 6 Recommendation 9To manage environmental risks: Co-ordination of the numerous bodies with regulatory responsibilities for shale gas extraction should ber An Environmental Risk Assessment (ERA) should maintained. A single body should take the lead. be mandatory for all shale gas operations, Consideration should be given to: involving the participation of local communities at the earliest possible opportunity. r Clarity on roles and responsibilities.r The ERA should assess risks across the entire r Mechanisms to support integrated ways of lifecycle of shale gas extraction, including the working. disposal of wastes and well abandonment. Seismic risks should also feature as part of r More formal mechanisms to share information. the ERA. r Joined-up engagement of local communities.Recommendation 7Best practice for risk management should be r Mechanisms to learn from operational andimplemented: regulatory best practice internationally.r Operators should carry out goal based risk Recommendation 10 assessments according to the principle of The Research Councils, especially the Natural reducing risks to As Low As Reasonably Environment Research Council, the Engineering Practicable (ALARP). The UK’s health and safety and Physical Sciences Research Council and the regulators and environmental regulators should Economic and Social Research Council, should work together to develop guidelines specific to consider including shale gas extraction in their shale gas extraction to help operators do so. research programmes, and possibly a cross-Research Council programme. Priorities should includer Operators should ensure mechanisms are put in research into the public acceptability of the extraction place to audit their risk management processes. and use of shale gas in the context of UK policies on climate change, energy and the wider economy.r Risk assessments should be submitted to the regulators for scrutiny and then enforced through monitoring activities and inspections.r Mechanisms should be put in place to allow the reporting of well failures, as well as other accidents and incidents, between operators. The information collected should then be shared to improve risk assessments and promote best practices across the industry.Recommendation 8The UK’s regulators should determine theirrequirements to regulate a shale gas industry shouldit develop nationwide in the future. Skills gaps andrelevant training should be identified. Additionalresources may be necessary. Shale gas extraction in the UK: a review of hydraulic fracturing 7
  8. 8. SUMMARY Terms of reference 6JG 7- )QXGTPOGPVoU %JKGH 5EKGPVKƂE #FXKUGT 5KT Methodology John Beddington FRS, asked the Royal Society and A Working Group was set up to oversee this project the Royal Academy of Engineering to carry out an (see Appendix 1). The Working Group met on six KPFGRGPFGPV TGXKGY QH VJG UEKGPVKƂE CPF GPIKPGGTKPI occasions when it was briefed by other experts. evidence relating to the technical aspects of the Consultations with other experts and stakeholders risks associated with hydraulic fracturing to inform were held between meetings. Submissions were government policymaking about shale gas extraction received from a number of individuals and learned in the UK. societies (see Appendix 2). This report has been reviewed by an expert Review Panel (see Appendix 3) The terms of reference of this review were: and approved by the Engineering Policy Committee of the Royal Academy of Engineering and the Council r What are the major risks associated with hydraulic of the Royal Society. fracturing as a means to extract shale gas in the UK, including geological risks, such as seismicity, The Royal Academy of Engineering and The Royal and environmental risks, such as groundwater 5QEKGV[ CTG ITCVGHWN VQ VJG )QXGTPOGPV 1HƂEG HQT contamination? 5EKGPEG HQT KVU ƂPCPEKCN UWRRQTV HQT VJKU TGXKGY r Can these risks be effectively managed? If so, how? This report has analysed environmental and health and safety risks. Climate risks have not been analysed. The risks addressed in this report are restricted to those associated with the onshore extraction of shale gas. The subsequent use of shale gas has not been addressed.8 Shale gas extraction in the UK: a review of hydraulic fracturing
  9. 9. CHAPTER 1Introduction1.1 Hydraulic fracturing pumped into the well to maintain the pressure in theShale is a common type of sedimentary rock formed well so that fracture development can continue andfrom deposits of mud, silt, clay and organic matter. proppant can be carried deeper into the formationShale gas mainly consists of methane, although (API 2009). A well may be too long to maintainother gases may also be present, trapped in shale sufficient pressure to stimulate fractures across itswith very low permeability. Shale gas does not entire length. Plugs may be inserted to divide the wellreadily flow into a well (‘produce’). Additional into smaller sections (‘stages’). Stages are fracturedstimulation by hydraulic fracturing (often termed sequentially, beginning with the stage furthest away‘fracking’) is required to increase permeability (see and moving towards the start of the well. AfterFigure 1). Once a well has been drilled and cased fracturing, the plugs are drilled through and the well(‘completed’), explosive charges fired by an electric is depressurised. This creates a pressure gradientcurrent perforate holes along selected intervals so that gas flows out of the shale into the well.of the well within the shale formation from which Fracturing fluid flows back to the surface (‘flowbackshale gas is produced (‘production zone’). Pumps water’) but it now also contains saline waterare used to inject fracturing fluids, consisting of with dissolved minerals from the shale formationwater, sand (‘proppant’) and chemicals, under (’formation water’). Fracturing fluid and formationhigh pressure into the well. The injection pressure water returns to the surface over the lifetime of thegenerates stresses in the shale that exceed its well as it continues to produce shale gas (‘producedstrength, opening up existing fractures or creating water’). Although definitions vary, flowbacknew ones. The fractures extend a few hundred water and produced water collectively constitutemetres into the rock and the newly created fractures ‘wastewaters’ (EPA 2011).are propped open by the sand. Additional fluids are Shale gas extraction in the UK: a review of hydraulic fracturing 9
  10. 10. CHAP TER 1 Figure 1 An illustration of hydraulic fracturing (Al Granberg/ProPublica) Fracturing fluids are injected under pressure to stimulate fractures in the shale. The fractures are propped open by sand contained in the fracturing fluid so that shale gas can flow out of the shale into the well. Well Sand keeps fractures open Shale gas Fracture flows from fractures into well Mixture of Well water, sand and chemical additives Fractures Shale 1.2 Stages of shale gas extraction through them and access only a small volume of Shale gas extraction consists of three stages: the shale. Horizontal wells are likely to be drilled and fractured. Once a shale formation is reached r Exploration. A small number of vertical wells by vertical drilling, the drill bit can be deviated to (perhaps only two or three) are drilled and run horizontally or at any angle. fractured to determine if shale gas is present and can be extracted. This exploration stage may r Abandonment. Like any other well, a shale gas include an appraisal phase where more wells well is abandoned once it reaches the end of (perhaps 10 to 15) are drilled and fractured to its producing life when extraction is no longer characterise the shale; examine how fractures will economic. Sections of the well are filled with tend to propagate; and establish if the shale could cement to prevent gas flowing into water-bearing produce gas economically. Further wells may be zones or up to the surface. A cap is welded into drilled (perhaps reaching a total of 30) to ascertain place and then buried. the long-term economic viability of the shale. 1.3 The global policy context r Production. The production stage involves the commercial production of shale gas. Shales 1.3.1 Potential global shale gas resources with commercial reserves of gas will typically ‘Gas in place’ refers to the entire volume of gas be greater than a hundred metres thick and contained in a rock formation regardless of the will persist laterally over hundreds of square ability to produce it. ‘Technically recoverable kilometres. These shales will normally have resources’ refers to the volume of gas considered shallow dips, meaning they are almost horizontal. to be recoverable with available technology. ‘Proved Vertical drilling would tend to pass straight reserves’ refers to that volume of technically10 Shale gas extraction in the UK: a review of hydraulic fracturing
  11. 11. CHAPTER 1recoverable resources demonstrated to be estimates the total volume of technically recoverableeconomically and legally producible under existing shale gas worldwide to be 6,622 tcf. The USA haseconomic and operating conditions. approximately 862 tcf, and China 1,275 tcf (see Figure 2). In Europe, Poland and France are two ofShale gas could increase global natural gas the most promising shale gas countries with 187resources by approximately 40%. The US Energy tcf and 180 tcf of technically recoverable resources,Information Administration (EIA) estimates the global respectively. Norway, Ukraine and Sweden may alsotechnically recoverable resources of natural gas possess large technically recoverable resources.(largely excluding shale gas) to be approximately The EIA estimates the UK’s technically recoverable16,000 trillion cubic feet (tcf) (EIA 2011). The EIA resources to be 20 tcf (EIA 2011) Figure 2 Estimates of technically recoverable shale gas resources (trillion cubic feet, tcf) based on 48 major shale formations in 32 countries (EIA 2011) Russia, Central Asia, Middle East, South East Asia and central Africa were not addressed in the Energy Information Administration report from which this data was taken. 83 Norway 388 Canada UK 20 187 Poland France 180 862 USA 1275 China Algeria 231 Pakistan 51 290 Libya 681 Mexico India 63 226 Brazil 62 Paraguay Australia 396 64 Chile 485 South Africa 774 Argentina1.3.2 Global climate change and energy security molecule of methane is greater than that of carbonShale gas is championed by some commentators as dioxide, but its lifetime in the atmosphere is shorter.a ‘transition fuel’ in the move towards a low carbon On a 20-year timescale, the global warming potentialeconomy, helping to displace higher-emitting fuels, of methane is 72 times greater than that of carbonsuch as coal (Brinded 2011). Others argue that shale dioxide. On a century timescale, it is 25 times greatergas could supplement rather than displace coal use, (IPCC 2007).further locking in countries to a fossil fuel economy(Broderick et al 2011). The development of shale gas 1.4 Environmental concerns in the USAcould also reduce and/or delay the incentive to invest Hydraulic fracturing was pioneered in the 1930s andin zero- and low-carbon technologies and renewable ƂTUV WUGF CHVGT VJG 5GEQPF 9QTNF 9CT KP VJG 75# VQenergy (Broderick et al 2011, Stevens 2010). exploit the relatively shallow Devonian Shale in the GCUVGTP 75 CPF #PVTKO 5JCNG KP VJG /KFYGUV 6JG ƂTUVThere are concerns that even small leakages of well to be hydraulically fractured was in 1949. Onlymethane during shale gas extraction may offset the a modest volume of gas was recovered. Advanceseffects of lower carbon dioxide emissions (Howarth in technology in the late 1980s and early 1990s ledet al 2011). The global warming potential of a to directional drilling and hydraulic fracturing in the Shale gas extraction in the UK: a review of hydraulic fracturing 11
  12. 12. CHAP TER 1 Barnett Shale in Texas (Selley 2012). An important 1.4.1 Improper operational practices turning point came in the 1990s. Geochemical There has been widespread concern in the USA studies of the Antrim Shale of the Michigan Basin about the environmental impact of hydraulic revealed that the gas being released was not fracturing. One cause for concern has been improper thermogenic (produced by the alteration of organic operational practices. A US Environmental Protection matter under high temperatures and pressures over Agency (EPA) study reported that hydraulic fracturing long time periods) but was biogenic (produced had contaminated groundwater and drinking by bacteria) (Martini et al 1998). This discovery water supplies in Pavillion, Wyoming (DiGiulio et opened up new areas for exploration where the al 2011). The well casing was poorly constructed, shale had previously been deemed either immature and the shale formations that were fractured were or over-mature for thermogenic gas generation. as shallow as 372m. Many claims of contaminated At the same time, progress was being made in water wells due to shale gas extraction have been methods of drilling, such as directional drilling that made. None has shown evidence of chemicals could steer the drill bit to exploit regions with high HQWPF KP J[FTCWNKE HTCEVWTKPI ƃWKFU 9CVGT YGNNU KP concentrations of carbon and where the shale is areas of shale gas extraction have historically shown most amenable to being fractured. By 2002-03, the high levels of naturally occurring methane before combination of hydraulic fracturing and directional operations began. Methane detected in water wells drilling made shale gas commercially viable. with the onset of drilling may also be mobilised by vibrations and pressure pulses associated with the Shale gas production has been enhanced by US lease drilling (Groat and Grimshaw 2012). In 2011, the EPA regulations that require a leaseholder to commence was directed by Congress to undertake a study to operations within a primary term period (normally better understand the potential impacts of hydraulic ƂXG [GCTU QT NQUG VJG NGCUG TGICTFNGUU QH RTKEG 5JCNG fracturing on drinking water resources. This EPA gas production in the USA has caused gas prices to study is examining impacts from the acquisition of fall as supply has outstripped demand. Shale gas has water and its mixing with chemicals to create fracture FKXGTUKƂGF FQOGUVKE GPGTI[ UWRRNKGU CPF TGFWEGF ƃWKF VJTQWIJ VQ VJG OCPCIGOGPV QH ƃQYDCEM CPF 75 FGRGPFGPEG QP KORQTVU QH NKSWGƂGF PCVWTCN ICU RTQFWEGF YCVGT KPENWFKPI FKURQUCN # ƂTUV TGRQTV Shale gas rose from 2% of US gas production in KU GZRGEVGF CV VJG GPF QH 6JG ƂPCN TGUWNVU 2000 to 14% in 2009, and is projected to rise to are due in 2014. In 2011, the Secretary of Energy more than 30% by 2020 (EIA 2011). Advisory Board Natural Gas Subcommittee submitted its recommendations to improve the safety and environmental performance of shale gas extraction (see Textbox 1).12 Shale gas extraction in the UK: a review of hydraulic fracturing
  13. 13. CHAPTER 1Textbox 1 Recommendations of the US Secretary of Energy Advisory Board Natural GasSubcommittee (DoE 2011a, DoE 2011b)Recommendations ready for implementation Recommendations ready for implementationprimarily by federal agencies primarily by state agenciesr Communication among federal and state r Measurements of groundwater should be regulators should be improved. Federal funds made prior to any shale gas operations to should be provided to support the non- provide a baseline to assess any claims of profit State Review of Oil and Natural Gas water contamination. Environmental Regulations (STRONGER) and Ground Water Protection Council (GWPC). r Microseismic monitoring should be carried STRONGER began as a voluntary programme out to assure that fracture growth is developed to improve state regulations and constrained to producing formations. has since emerged as a partnership between industry, non-profit groups and regulators that r Best practice for well construction should develops best practice, including through new be developed and implemented, including guidelines. pressure testing and cement bond logs, to verify rock formations have been properlyr Incentives should be provided for states to isolated. offer their regulation framework to peer review under STRONGER. Extra funding would r Inspections should be carried out to confirm allow GWPC to expand its Risk Based Data that operators have remediated any defective Management System that helps states collect well cementation effectively. Inspections and publicly share data, such as environmental should also be carried out at safety-critical monitoring of shale gas operations. stages of well construction and hydraulic fracturing.r Operators should disclose all chemicals used in fracturing fluid and not just those r The composition of water should be that appear on Material Safety Data Sheets. monitored and publicly reported at each Disclosure should be reported on a well-by- stage of shale gas extraction, including the well basis and made publicly available. Extra transport of water and waste fluids to, and funding would support GWPC’s fracturing fluid from, well sites. chemical disclosure registry, Frac Focus, so that information can be accessed, according to chemical, well, company and geography. Recommendations whose implementation require new partnershipsr Operators and regulators should be r A systems approach to water management encouraged to reduce air emissions using should be adopted, requiring more effective proven technologies and practices. Systems sharing of federal and state responsibilities. should be implemented to monitor air emissions from shale gas operations, the r Mechanisms should be established to engage results of which should be made publicly regulators, operators and local communities available. The data collected should be used to discuss measures to minimise operational to assess the carbon footprint of shale gas impacts, including scientific studies to assess extraction compared to other fuels. impacts on local water resources, land use, wildlife and ecology. Shale gas extraction in the UK: a review of hydraulic fracturing 13
  14. 14. CHAP TER 1 1.4.2 Exemptions from regulation and Awareness of Chemicals Act (FRAC ACT) bills Another cause for concern was a number of were introduced in the House of Representatives exemptions granted to shale gas extraction from and Senate. The FRAC ACT would have required federal regulations. The 2005 Energy Act exempted companies to disclose such details, although not the hydraulic fracturing from being considered an proprietary formula. These bills had been proposed ‘underground injection’ under the Safe Drinking in the previous session of Congress but never Water Act. Compliance with various federal became law. requirements to prevent water contamination was not necessary. Fracturing wastes are exempt Environmental protection remains mainly a state from disposal restrictions under the Resource responsibility. In some states, requirements Conservation and Recovery Act. Operators are exempted from federal regulation are still imposed exempt from certain liabilities and reporting through state regulation. Some states are revising requirements relating to waste disposal under their regulations with a particular focus on three the Comprehensive Environmental Responsibility, areas of concern: water abstraction and disclosure Compensation, and Liability Act. Exemption from QH HTCEVWTKPI ƃWKF EQORQUKVKQP YGNN EQPUVTWEVKQP the Emergency Planning and Community Right to and wastewater management (Groat and Grimshaw Know Act means the type and quantity of chemicals 2012). Some states may have more capacity and to be used in fracturing do not need to be disclosed experience to regulate shale gas operations than to the EPA. In 2010, the Fracturing Responsibility other states (see Textbox 2). Textbox 2 Complications of US state and federal regulation A study by the University of Texas at Austin r Well construction. Some states are updating reviewed state regulations and enforcement provisions for well construction, according capabilities in 16 US states where shale gas to site-specific operational and geological extraction is currently underway, or is anticipated conditions. (Groat and Grimshaw 2012). This study concluded that variation exists among states in r Wastewater management. Some states are the regulation of: requiring operators to formulate disposal plans. In some states, disposal is primarily by r Water abstraction and disclosure of underground injection. In others with less fracturing fluid composition. In some states, suitable subsurface conditions disposal is via groundwater is privately owned and subject discharge into publicly owned treatment works. to different requirements than in other states The latter method has been prohibited by some where groundwater is owned by the state and states. Other states require pre-treatment before subject to state abstraction permits. More discharge. In some shale gas areas, wastes from uniform disclosure of the composition multiple well sites are managed at a centralised of fracturing fluids may be needed among disposal site. state regulators. 1.5 Environmental concerns in Europe potential to extract and use unconventional fossil Shale gas extraction in Europe is at the exploration fuel resources, including shale gas, should be stage. It is many years away from US levels of assessed (European Council 2011). In 2012, the commercial production, especially in the light European Commission (EC) judged that its existing of differences in geology, public acceptability, legal framework was adequate to address shale gas population density, tax breaks and environmental extraction (Vopel 2012). Shale gas could reduce some regulation (Stevens 2010). In 2011, European European countries’ dependence on natural gas Union (EU) Heads of State concluded that Europe’s imports (European Parliament 2012b).14 Shale gas extraction in the UK: a review of hydraulic fracturing
  15. 15. CHAPTER 1The EC Directorate-General for the Environment 1.7 Concerns about seismicityis conducting a desk study on environmental and Concerns in the UK have focused on seismicityhealth risks associated with hydraulic fracturing induced by hydraulic fracturing. ‘Seismicity’ orto identify knowledge gaps. The EC Directorate- ‘seismic events’ refer to sudden phenomena thatGeneral for Climate Action is carrying out a similar release energy in the form of vibrations that travelstudy focused on gas emissions associated with through the Earth as sound (seismic) waves. Energyshale gas extraction, including potential leakages of may be released when rocks break and slide pastmethane. The EC Directorate-General for Energy has each other on surfaces or cracks (‘faults’). Energycarried out a project on licensing, authorising and may also be released when rocks break in tension,the issuing of operational permits for shale gas. The opening up cracks or fractures. The passage andJoint Research Centre (JRC) is examining whether TGƃGEVKQP QH UGKUOKE YCXGU ECP DG OQPKVQTGF D[the exposure scenarios of Chemical Safety Reports seismometers at seismic stations. Geophones areunder Registration, Evaluation, Authorisation and used along regular lines (‘seismic lines’) or gridsRestriction of Chemicals regulation are adequate VQ QDVCKP VYQ QT VJTGG FKOGPUKQPCN RTQƂNGU QH VJGfor shale gas extraction. The JRC is also assessing CTVJoU UWDUWTHCEG UVTWEVWTG nUGKUOKE TGƃGEVKQPthe potential impacts on water and land use under surveys’). Seismicity is measured according tovarious national and EU-wide scenarios. Results of the amount of energy released (magnitude) or thethese studies should be available by the end of 2012. effect that energy release has at the Earth’s surface (intensity) (see Textbox 3).All EU member states are members of an AdHoc Technical Working Group on Environmental On 1st April 2011, the Blackpool area in northAspects of Unconventional Fossil Fuels, In Particular England experienced seismicity of magnitudeShale Gas. The Working Group seeks to exchange 2.3 ML shortly after Cuadrilla Resources (‘Cuadrilla’,information; identify best practice; assess the hereafter) hydraulically fractured a well at its Preeseadequacy of regulation and legislation; and provide Hall site. Seismicity of magnitude 1.5 ML occurredENCTKV[ VQ QRGTCVQTU +V OGV HQT VJG ƂTUV VKOG KP on 27th May 2011 following renewed fracturing ofJanuary 2012 and was attended by representatives the same well. Hydraulic fracturing was suspended.of approximately two thirds of member states. The Cuadrilla commissioned a set of reports to investigateWorking Group may meet again in summer 2012 the cause of seismicity (de Pater and Baisch 2011).when the results of some of the aforementioned The Department of Energy and Climate ChangeEC research are published. It is unclear whether the (DECC) also commissioned an independentWorking Group will continue to meet thereafter. report that was published for public comment (Green et al 2012).1.6 MoratoriaEnvironmental concerns have led to moratoria onhydraulic fracturing for shale gas extraction in partsof the USA and in other countries. In May 2010, theMarcellus Shale Bill was passed in Pennsylvania,enforcing a three-year moratorium while acomprehensive environmental impact assessmentis carried out. In August 2010, New York Stateimposed a temporary moratorium, pending furtherresearch into environmental impacts. Moratoriahave also been imposed elsewhere, including in theprovince of Quebec, Canada (March 2011), France(July 2011), South Africa (August 2011) and Bulgaria(January 2012). Shale gas extraction in the UK: a review of hydraulic fracturing 15
  16. 16. CHAP TER 1 Textbox 3 Measuring seismic magnitude and intensity Magnitude scales are calibrated to Richter’s The frequency of the radiated seismic waves is magnitude scale. The scale is logarithmic so the proportional to the size of the fracture. Since smallest events can have negative magnitudes. engineered hydraulic fractures are typically small, Each unit step in the scale indicates a 32-fold seismic events induced by hydraulic fracturing increase in the energy released. Seismic intensity only produce high frequency radiated seismic is an indication of how much a seismic event waves, and so do not produce ground shaking affects structures, people and landscapes at the that will damage buildings. The number of people Earth’s surface. Surface effects are compared who feel small seismic events is dependent on the to a scale originally developed by Mercalli background noise. that considers who can feel an event along with visual and structural effects. The Mercalli The British Geological Survey (BGS) runs a network scale has been superseded by the European of approximately 100 stations to monitor seismicity Macroseismic Scale that incorporates new in the UK. The Atomic Weapons Establishment knowledge about how buildings behave during also has a limited number of stations to monitor seismic events. international compliance with the Comprehensive Nuclear Test Ban Treaty. Other seismic stations The effect a given seismic event will have at include those maintained for research by the earth’s surface depends on several factors. universities. The detection limit of this national The deeper a seismic event occurs the more its network is a function of background noise that radiated energy is attenuated. A deeper seismic OC[ KPENWFG VTCHƂE VTCKPU CPF QVJGT KPFWUVTKCN event will have a lower intensity than a shallower noise, as well as natural noise, such as wind. Given event of the same magnitude. Different average background noise conditions in mainland materials attenuate seismic waves to different UK, a realistic detection limit of BGS’ network is degrees. Soft rocks, such as shale, attenuate magnitude 1.5 ML. For regions with seismic waves more than hard rocks, such more background noise, the detection limit may as granite. Different buildings and structures be closer to magnitude 2-2.5 ML. Vibrations from respond differently depending on how they are a seismic event of magnitude 2.5 ML are broadly constructed. The response of a building to a GSWKXCNGPV VQ VJG IGPGTCN VTCHƂE KPFWUVTKCN CPF seismic event also depends on the frequency other noise experienced daily (see Table 1). of the ground shaking. High frequencies (above 20-30 Hz) will do relatively little damage.16 Shale gas extraction in the UK: a review of hydraulic fracturing
  17. 17. CHAPTER 1Table 1 The average annual frequency of seismic events in the UK Magnitude (ML) Frequency in the UK Felt effects at the surface -3.0 Not detected by BGS’ network Not felt -2.0 Not detected by BGS’ network Not felt -1.0 Not detected by BGS’ network Not felt 0.0 Not detected by BGS’ network Not felt 1.0 100s each year Not felt, except by a very few under especially favourable conditions. 2.0 25 each year Not felt, except by a very few under especially favourable conditions. 3.0 3 each year (GNV D[ HGY RGQRNG CV TGUV QT KP VJG WRRGT ƃQQTU QH buildings; similar to the passing of a truck. 4.0 1 every 3-4 years Felt by many people, often up to tens of kilometres away; some dishes broken; pendulum clocks may stop. 5. 0 1 every 20 years Felt by all people nearby; damage negligible in buildings of good design and construction; few instances of fallen plaster; some chimneys broken.1.8 The UK policy context 6JG ƂTUV 7- YGNN VQ GPEQWPVGT UJCNG ICU YCU FTKNNGFThe UK has experience of hydraulic fracturing and KP +VU UKIPKƂECPEG CV VJG VKOG YGPV WPPQVKEGFdirectional drilling for non-shale gas applications. as abundant conventional reservoirs made shaleOver the last 30 years, more than 2,000 wells have gas extraction uneconomic. It was not until thebeen drilled onshore in the UK, approximately 200 mid-1980s that research began into the potential(10%) of which have been hydraulically fractured for gas production from UK shales. In 2003, theto enhance recovery. The combination of hydraulic Petroleum Revenue Act was repealed, exemptingfracturing and directional drilling allowed the shale gas production from the Petroleum RevenueFGXGNQROGPV QH 9[VEJ (CTO ƂGNF KP QTUGV KP Tax (Selley 2012). In 2008, 97 Petroleum Exploration1979. Discovered by British Gas in the 1970s and and Development Licences were awarded for shaleQRGTCVGF D[ $TKVKUJ 2GVTQNGWO UKPEG VJG ƂGNF gas exploration in the UK during the 13th Round ofis responsible for the majority of UK onshore oil Onshore Licensing (see chapter 7). A 14th licensingRTQFWEVKQP CPF KU WTQRGoU NCTIGUV QPUJQTG QKN ƂGNF round is pending.Over 200 wells have been drilled. Drilling verticallyonshore then horizontally out to sea has proved Industry interest in shale gas extraction in themore cost-effective than building offshore platforms, UK includes:allowing oil to be produced beneath the Sandbanksestate, Bournemouth, from oil reservoirs 10km away. r England. Five potential shale gas explorationIn 1996, British Gas hydraulically fractured a well well sites have been identified by Cuadrilla inKP VJG NUYKEM )CU ƂGNF KP .CPECUJKTG MO HTQO Lancashire. The first test well was drilled in AugustCuadrilla’s Preese Hall well). Gas has been produced 2010 at Preese Hall; a second at Grange Hill Farmfrom it ever since. In the 1990s, several wells were later that year; and a third near the village ofalso fractured in the UK to extract coal bed methane. Banks in August 2011. Hydraulic fracturing has Shale gas extraction in the UK: a review of hydraulic fracturing 17
  18. 18. CHAP TER 1 been undertaken at only one site. DECC has also 1.8.1 UK climate change and energy security granted a license for a site in Balcombe, West The UK government has agreed to meet a number of Sussex identified by Cuadrilla. Three possible sites domestic and European targets to decarbonise the have been identified in the Mendip Hills by UK UK economy (Moore 2012). The Climate Change Act Methane and Eden Energy. Planning permission 2008 calls for an 80% reduction in greenhouse gas has been sought for boreholes for geological emissions by 2050. This includes an interim target samples. UK Methane has stated it has no interest of a 34% reduction in emissions by 2020 and a 50% in hydraulic fracturing at this stage. One site has reduction in emissions by the 2023–2027 budget been identified in Woodnesborough, Kent, by (all from a baseline of 1990). The EU has a target to Coastal Oil and Gas Ltd. Planning permission reduce EU-wide greenhouse gas emissions by 20% has been granted. Neither Cuadrilla’s West between 1990 and 2020. It has also agreed that 20% Sussex nor Coastal Oil and Gas Ltd’s Kent sites of total energy production across the EU should be have yet been granted permission for drilling or generated by renewable sources, and so the UK hydraulic fracturing. has committed to sourcing 15% of its energy from renewables. r Wales. Three sites have been identified by Coastal Oil and Gas Ltd. DECC has given permission for The House of Commons Energy and Climate Change drilling at two of these sites, but not hydraulic Committee carried out an inquiry into shale gas fracturing. Planning permission has been granted in 2011. The inquiry considered the prospects for for the sites at Neath and Maesteg where wells shale gas in the UK; risks and hazards involved; will be deepened to obtain geological samples. potential carbon footprint of large-scale shale gas Planning permission was refused at Llandow, Vale extraction; and implications for the UK of large- of Glamorgan. The decision is being appealed with scale shale gas production around the world (HoC a public inquiry. 6JG %QOOKVVGG EQPENWFGF VJCV KH C UKIPKƂECPV amount of shale gas enters the UK market (whether r Scotland. Although potential shale formations from domestic or foreign sources), it will probably do exist in Scotland, to date there has been discourage investment in more expensive, lower no interest in shale gas extraction. Consent for carbon emission renewables (HoC 2011). hydraulic fracturing has been provided to one operator with an interest in extracting coal bed Over the last decade, the UK has experienced methane. reduced domestic production from the North Sea and an increased reliance on natural gas imports. r Northern Ireland. Tamboran Resources has New pipelines from Norway and the Netherlands an interest to extract shale gas in an area that CPF NKSWGƂGF PCVWTCN ICU OCMG WR VJG FKHHGTGPEG extends across the border between Northern The House of Commons Energy and Climate Change Ireland and the Republic of Ireland. Committee also concluded that domestic resources could reduce the UK’s dependence on imports, but The Environment Agency (EA), serving England and the effect on energy security may be ‘unlikely to be Wales, has been reviewing the adequacy of existing enormous’ (HoC 2011). The UK has an open gas regulation. In 2011, the Scottish Environmental market with large new import infrastructure and a Protection Agency (SEPA) published a position diversity of potential gas suppliers (Moore 2012). statement based on its preliminary views of shale gas extraction (SEPA 2011). The Northern Ireland 1.8.2 Joint academies review Environment Agency is working with the Irish 6JG 7- )QXGTPOGPVoU %JKGH 5EKGPVKƂE #FXKUGT 5KT environmental regulator to develop a regulatory John Beddington FRS, asked the Royal Society and framework suitable for transboundary activities. the Royal Academy of Engineering to carry out an KPFGRGPFGPV TGXKGY QH VJG UEKGPVKƂE CPF GPIKPGGTKPI evidence to inform government policymaking about shale gas extraction in the UK. The following chapters analyse environmental and health and safety risks associated with the onshore extraction of shale gas.18 Shale gas extraction in the UK: a review of hydraulic fracturing
  19. 19. CHAPTER 2Surface operations (TCEVWTKPI ƃWKF allowing each stage to address local conditions,6JG ƃWKFU OQUV EQOOQPN[ WUGF HQT J[FTCWNKE such as shale thickness; presence of natural faults;fracturing are water-based. The water can be and proximity to other well systems (API 2009).abstracted from surfacewater bodies, such as rivers Operations require specialised equipment, includingand lakes, or from groundwater bodies, such as ƃWKF UVQTCIG VCPMU RTQRRCPV VTCPURQTV GSWKROGPVaquifers or public and private water sources. Sand and blending and pumping equipment. Theseis added as a proppant to keep fractures open. components are assembled and linked to monitoringVarious chemicals are also added (see Figure 3). U[UVGOU UQ VJCV CFLWUVOGPVU ECP DG OCFG VQ ƃWKFDuring multistage fracturing, a series of different XQNWOG CPF EQORQUKVKQP ƃWKF KPLGEVKQP TCVG CPFXQNWOGU QH HTCEVWTKPI ƃWKFU KU KPLGEVGF YKVJ URGEKƂE pressure.concentrations of proppant and other additives, (KIWTG 6[RKECN EQORQUKVKQP QH HTCEVWTKPI ƃWKF D[ XQNWOG UQWTEG $TKVKUJ )GQNQIKECN 5WTXG[ The 0.17% of chemical additives may include scale inhibitor to prevent the build up of scale on the walls of the well; acid to help initiate fractures; biocide to kill bacteria that can produce hydrogen sulphide CPF NGCF VQ EQTTQUKQP HTKEVKQP TGFWEGT VQ TGFWEG HTKEVKQP DGVYGGP VJG YGNN CPF ƃWKF KPLGEVGF KPVQ KV CPF UWTHCEVCPV VQ TGFWEG VJG XKUEQUKV[ QH VJG HTCEVWTKPI ƃWKF Additives 0.17% e Sand Water 5.23% d 94.60% a c b a. Scale inhibitor b. Acid c. Biocide d. Friction reducer e. Surfacant2.1.1 Disclosing the composition of QH HTCEVWTKPI ƃWKF QT YCUVGYCVGTU QPUKVG ECP DG fracturing fluid mitigated using established best practices. In theIn the USA, there are calls for operators to disclose UK, installing impermeable site lining (‘bunding’) isHWNN[ VJG EQORQUKVKQP QH HTCEVWTKPI ƃWKF CFFKVKXGU UGG typically a condition of local planning permission.section 1.4.2). This is already required in the UK. In 6JG KORCEV QH HTCEVWTKPI ƃWKF URKNNU ECP DG HWTVJGTthe UK, the environmental regulator has the power mitigated by using non-hazardous chemicalsunder the Water Resources Act 1991 to demand the where possible. In the UK, there is no generic listFKUENQUWTG QH VJG EQORQUKVKQP QH HTCEVWTKPI ƃWKFU QH CRRTQXGF EJGOKECNU HQT WUG KP HTCEVWTKPI ƃWKF The environmental regulators use a methodology2.1.2 Spills of fracturing fluid developed by the Joint Agencies Groundwater5WTHCEG URKNNU QH HTCEVWTKPI ƃWKF OC[ RQUG C ITGCVGT Directive Advisory Group to assess the hazardcontamination risk than hydraulic fracturing itself potential of any chemical to be used, according to(Groat and Grimshaw 2012). The impact of any spills VJG URGEKƂE UKVG CPF NQECN J[FTQIGQNQIKECN EQPFKVKQPU Shale gas extraction in the UK: a review of hydraulic fracturing 19
  20. 20. CHAP TER 2 2.2 Water requirements 2.2.2 Alternatives to water There are concerns that hydraulic fracturing could Another option would be to use waterless fracturing TGSWKTG XQNWOGU QH YCVGT VJCV YQWNF UKIPKƂECPVN[ ƃWKFU 6JGUG KPENWFG IGNU CPF ECTDQP FKQZKFG CPF deplete local water resources (Entrekin et al 2011). nitrogen gas foams (King 2010). These techniques are Reported estimates for the volumes of water required important where shales are susceptible to damage for shale gas extraction vary according to local from water-based fracturing (King 2010). Gelled liquid geology, well depth and length and the number of RGVTQNGWO ICU .2) HTCEVWTKPI ƃWKFU EQWNF DQQUV hydraulic fracturing stages. In the UK, under the initial production rates and allow near full recovery Water Resources Act 1991, an operator is required QH VJG HTCEVWTKPI ƃWKFU YKVJKP FC[U QH UVKOWNCVKQP to seek an abstraction permit from the environmental 6JG WUG QH VJGUG ƃWKFU RCTVKEWNCTN[ RTQRCPGDCUGF regulator if more than 20m3 of water is to be LPG, could reduce the toxicity of wastewaters since abstracted per day from surface or groundwater they do not dissolve salts, heavy metals or Naturally bodies. If water is instead sourced from a mains Occurring Radioactive Material (NORM) in shales to supply, the water company will need to ensure it can the extent that water does. still meet the conditions of the abstraction permit that it will already be operating under. 2.3 Managing wastewaters Approximately 25% to 75% of the injected fracturing Overall water use is important. Estimates indicate ƃWKF ƃQYU DCEM VQ VJG UWTHCEG YJGP VJG YGNN KU that the amount needed to operate a hydraulically FGRTGUUWTKUGF 6JKU ƃWKF KU OKZGF YKVJ OGVJCPG fractured shale gas well for a decade may be and saline water containing minerals from the shale equivalent to the amount needed to water a golf HQTOCVKQP 6JG XQNWOG QH ƃQYDCEM YCVGT FGRGPFU course for a month; the amount needed to run a on the properties of the shale, the fracturing design /9 EQCNƂTGF RQYGT RNCPV HQT JQWTU CPF CPF VJG V[RG QH HTCEVWTKPI ƃWKF WUGF -KPI the amount lost to leaks in United Utilities’ region Produced water will continue to return to the in north west England every hour (Moore 2012). surface over the well’s lifetime. These wastewaters The rate of abstraction is also important. Hydraulic typically contain salt, natural organic and inorganic fracturing is not a continuous process. Water is compounds, chemical additives used in fracturing required periodically during drilling and then at each ƃWKF CPF 014/ 02% 8GT[ NKVVNG KU EWTTGPVN[ fracturing stage. Operators could consult water known about the properties of UK shales to explain utilities companies to schedule operations to avoid YJCV HTCEVKQP QH HTCEVWTG ƃWKF YKNN TGVWTP CU ƃQYDCEM periods when water supplies are more likely to be water, as well as the composition of formation under stress (Moore 2012). waters and produced water.1 2.2.1 Alternative sources of water 2.3.1 Storing wastewaters Water stress can be avoided by using alternative In the USA, wastewaters have historically been sources of water. Freshwater was necessary early stored onsite in open pits, such as excavated and in the development of certain US shales when lined containment ponds (API 2009). The possible friction reducers, scale inhibitors, and particularly leakage of liners has led to calls to avoid the use of UWTHCEVCPVU UJQYGF RGTHQTOCPEG FKHƂEWNVKGU YJGP pits in favour of closed loop steel tanks and piping mixed in saline water (King 2010). Technologies systems (Groat and Grimshaw 2012). Open storage developed to overcome these problems in offshore ponds are not permitted in the UK. Wastewaters hydraulic fracturing (where the use of seawater is are instead stored in closed metal tanks before more prevalent) are now being applied to onshore being treated. Leaks or spills of wastewaters can operations (Harris and van Batenburg 1999). The be managed in the same way as spills of fracturing use of saline water from deep aquifers is being ƃWKF UGG UGEVKQP 6JKU JCCTF KU PQV WPKSWG considered in some US shales (Yost 2011). to shale gas extraction but common to many industrial processes. 1 Contribution from Professor Richard Davies, Director of Energy Institute, University of Durham (private correspondence)20 Shale gas extraction in the UK: a review of hydraulic fracturing
  21. 21. CHAPTER 22.3.2 Reuse of wastewaters 2.3.4 Transporting wastewatersIntegrated operational practices should be adopted The transport of wastewaters offsite is carried out byto minimise water use and avoid abstracting water road haulage companies licensed by the UK’s healthfrom supplies that may be under stress. Recycling and safety regulators with experience of transportingwastewater where possible would reduce the hazardous substances. The UK’s environmentalvolumes of wastewater in need of disposal, although TGIWNCVQTU KUUWG ECTTKGT TGIKUVTCVKQP EGTVKƂECVGUit could concentrate contaminants and thereby and the Department of Transport and Vehicle andcomplicate disposal. Operator Services Agency are responsible for vehicle licensing and testing.Wastewaters can be diluted with freshwater andthen reused in subsequent fracturing operations. 2.4 Disposal of wastewatersPre-treatment may be necessary. The composition Disposal wells may be necessary if wastewaterof wastewaters changes over the lifetime of a volumes exceed the capabilities of onsite, closed-well. The most appropriate treatment will depend NQQR UVQTCIG VCPM U[UVGOU +PLGEVKQP QH YCUVG ƃWKFUon the waters’ degree of salinity (King 2010). The into porous and permeable rock formations has beenenvironment in which some shales were initially VJG RTKOCT[ FKURQUCN QRVKQP HQT YCUVG ƃWKFU HTQO VJGdeposited was marine (King 2012). Produced US oil and gas industry (DoE 2009). Disposal wellswater in the latter stages of shale gas extraction are often depleted oil and gas wells, but wells can beis more saline owing to the increased amount of FTKNNGF URGEKƂECNN[ HQT FKURQUCN KH KV KU GEQPQOKE VQ FQsaline formation water that it contains. Desalination so. The site of disposal wells depends on geologicaltechnologies are being developed to control conditions and regulation. In the USA, some wastessalinity and support reuse of wastewaters. These are transported to disposal sites by truck or pipelinetechnologies concentrate salt and recover water (DoE 2009).through evaporation, distillation, electric separationor chemical treatment. The most common treatment 2.4.1 Disposing of fluidsWUGU UGNGEVKXG OGODTCPGU VJCV ƂNVGT QWV UCNV KQPU Wastewaters are considered to be an ‘extractivewhen high pressure is applied across them. As waste’, and so are regulated under the Mining Wastewell as producing pure water, these desalination Directive. Operators are required to formulate wastetechnologies typically produce a small amount of management plans that identify how wastes are tobrine slurry that may be converted to solid waste in minimised, treated, recovered and disposed of. Thisa crystalliser before disposal (ALL Consulting 2005). includes identifying environmental and health impactsMicroorganisms, such as bacteria, can exist even and measures to address them, including control andin deep shale formations, and so may be present monitoring activities. Disposal would be regulatedin the formation water within wastewaters. These in the UK under the Mining Waste Directive andmicroorganisms need to be removed for health Water Framework Directive. An environmental permitand safety and commercial reasons. Bacterial can would be necessary, as well as pre-treatment, beforeproduce hydrogen sulphide and acids that corrode discharge into a disposal well. If wastewaters containwell casings, and so potentially contribute to well 014/ CDQXG URGEKƂGF NKOKVU C HWTVJGT RGTOKV YQWNFHCKNWTG KUKPHGEVKQP VGEJPKSWGU KPENWFG ƂNVTCVKQP be required. The Radioactive Substances Regulationtechniques, as well as ultraviolet light, chlorine, would also apply. Currently, a disposal well would beiodine, ozone and acid treatments (ALL Consulting constructed in the UK according to the Borehole Sites2005). and Operations Regulations 1995 if the disposal well was in a mining area and to a depth of 30m or greater.Pre-treatment could take place onsite, although this Offshore disposal would involve extra environmentalis currently expensive. Technologies could build on regulations, such as those under the ConventionVJQUG CNTGCF[ WUGF VQ VTGCV YCUVG ƃWKF HTQO QHHUJQTG for the Protection of the Marine Environment of theoil and gas extraction. Alternatively, wastewaters North-East Atlantic (the OSPAR Convention).could be transported to a treatment facility offsite.Numerous facilities exist in the UK with extensiveexperience of treating similar wastes from a rangeof industrial sectors. Shale gas extraction in the UK: a review of hydraulic fracturing 21
  22. 22. CHAP TER 2 2.5 Disposal of solid wastes Shale tends to contain more uranium than other RECOMMENDATION types of rocks. The radioactive decay of uranium-238 Water should be managed in an produces radium-226 that decays to radon-222 KPVGITCVGF YC[ gas. Other NORM found in shales includes thorium and lead-210, concentrations of which vary from r Techniques and operational practices formation to formation. NORM in shales is usually at should be implemented to minimise NGXGNU UKIPKƂECPVN[ NQYGT VJCP UCHG NKOKVU QH GZRQUWTG water use and avoid abstracting water NORM dissolves in formation water, so wastewaters from supplies that may be under stress. need careful management should NORM become r Wastewater should be recycled and more concentrated during treatment (King 2012). reused where possible. Dissolved NORM may settle out to form solid wastes, such as mineral scale on the inside of wells r Options for treating and disposing of and pipes or sludge that accumulates in storage wastes should be planned from the or treatment tanks. Scale is composed primarily of outset. The construction, regulation and insoluble barium, calcium and strontium compounds siting of any future onshore disposal that precipitate out of wastewaters due to changes wells need further investigation. in temperature and pressure. Radium is chemically similar to these elements, and so is incorporated into the scales. Sludge settles out of wastewaters 2.6 Managing methane and other emissions and consists of oily solids often containing silica 8GPVKPI CPF ƃCTKPI QH OGVJCPG CPF QVJGT GOKUUKQPU compounds and barium. are controlled through conditions of Petroleum Exploration and Development Licences. The health NORM management is not unique to shale gas and safety regulator places similar controls under GZVTCEVKQP 014/ KU RTGUGPV KP YCUVG ƃWKFU HTQO VJG the Borehole Sites and Operations Regulations 1995 conventional oil and gas industries, as well as and and Offshore Installations and Wells (Design and mining industries, such as coal and potash. Much Construction) Regulations 1996. Local authorities are work has been carried out globally on monitoring responsible under the Environmental Protection Act levels of radioactivity and handling NORMs in the 1990 to inspect sites for odour and noise associated oil and gas industries. For example, it is standard YKVJ VJG XGPVKPI QT ƃCTKPI QH ICU .QECN CWVJQTKVKGU practice to sandblast pipes to remove scale or to use also have a statutory duty under the Air Quality a rotating drill bit. The removed scale is then placed in Standards Regulations 2007 to monitor emissions to sealed containers for later disposal. Scale can also be ensure they do not breach local air quality standards. removed by dissolving NORM in an aqueous solvent Methane contained in wastewater can be regulated before re-injecting the NORM-containing solution into by the environmental regulator placing controls a disposal well (ALL Consulting 2005). on operators’ waste management plans (see section 2.4.1). In the UK, solid NORM wastes fall into one of three categories: very low concentration (‘out of scope’); low The Industrial Emissions Directive would apply if concentration; medium or high concentration (requires shale gas is processed before injection into the gas an EPR permit). An environmental permit is required pipeline or combusted to generate electricity and/ for disposing of NORM wastes that exceed ‘out of or heat onsite. A permit would then be needed, UEQRGo EQPEGPVTCVKQPU KURQUCN KP NCPFƂNN KU V[RKECN HQT requiring the operator to monitor emissions of solid wastes of low and medium concentrations. Some methane (and other air pollutants). Shale gas in offshore oil production facilities have permits allowing the UK is expected to be of high quality, so large some NORM wastes to be discharged directly to sea. scale processing may not be necessary. Operators22 Shale gas extraction in the UK: a review of hydraulic fracturing
  23. 23. CHAPTER 2should still monitor potential leakages of methaneand other emissions before, during and after shale RECOMMENDATIONgas operations. Monitoring before operations would 6Q FGVGEV RQVGPVKCN NGCMCIGU QH ICUindicate the effects of methane due to non-shale gasoperations in the area or natural seepage (methane r Operators should monitor potentialKU TGNGCUGF PCVWTCNN[ HTQO CNNWXKWO UQKNU NCPFƂNN UKVGU leakages of methane or other emissionsand peat deposits). One option would be to construct to the atmosphere before, during andsemi-permanent monitoring stations around the after shale gas operations.perimeter of a drilling site. Alternatively, emissions r The data collected by operators shouldcould be monitored near to the well. Both options be submitted to the appropriateface complications. Gas emissions would be diluted regulator. These data could informin the atmosphere before reaching monitoring wider assessments, such as the carbonstations, limiting their detection accuracy. Monitoring footprint of shale gas near to the well could be disturbed due tosurface equipment being changed at different stagesof operations. Monitoring data should be submittedto the appropriate regulator. Reliable data would beavailable to inform assessments of health impactson local populations (McKenzie et al 2012). Thesedata could also inform assessments of the carbonfootprint of shale gas extraction (see section 8.2.2).‘Green completion technologies’ are used in the USAVQ ECRVWTG CPF VJGP UGNN TCVJGT VJCP XGPV QT ƃCTGCP[ OGVJCPG CPF QVJGT ICUGU GOKVVGF HTQO ƃQYDCEMwater (DoE 2011b). These technologies separateQWV ICU YCVGT CPF UCPF KP ƃQYDCEM ƃWKF DGHQTGdirecting the recovered gas into pipelines. Methaneand carbon dioxide emissions are reduced comparedVQ XGPVKPI CPF ƃCTKPI OGVJCPG TGURGEVKXGN[ )TGGPcompletion technologies could allow emissionslevels similar to those associated with natural gasextraction (Broderick et al 2011). The EPA hasissued federal regulations making green completiontechnologies mandatory for hydraulic fracturing of allgas wells in the USA from 2015 onwards. No suchrequirements exist in the UK for exploratory activities.Consideration should be given the possible use ofgreen completion technologies, especially for anyfuture production activities in the UK, based on bestavailable technologies and operational best practices. Shale gas extraction in the UK: a review of hydraulic fracturing 23
  24. 24. CHAP TER 3 Well integrity ‘Well integrity’ refers to preventing shale gas from Well failure may arise from poor well integrity leaking out of the well by isolating it from other resulting from: subsurface formations (API 2009). The isolation is provided according to how the well is constructed. r Blowout. A blowout is any sudden and A series of holes (‘wellbores’) of decreasing diameter uncontrolled escape of fluids from a well and increasing depth are drilled and lined with steel to the surface. casing joined together to form continuous ‘strings’ of casing (see Figure 4): r Annular leak. Poor cementation allows contaminants to move vertically through the r Conductor casing. Set into the ground to a well either between casings or between casings depth of approximately 30 metres, the conductor and rock formations. casing serves as a foundation for the well and prevents caving in of surface soils. r Radial leak. Casing failures allow fluid to move horizontally out of the well and migrate into the r Surface casing. The next wellbore is drilled and surrounding rock formations. sealed with a casing that runs past the bottom of any freshwater bearing zones (including but not Figure 4 An example of a shale gas limited to drinking water aquifers) and extends all well design (DoE 2009) the way back to the surface. Cement is pumped down the wellbore and up between the casing and the rock until it reaches the surface. Conductor casing r Intermediate casing. Another wellbore is drilled and lined by an intermediate casing to isolate the Aquifer well from non-freshwater zones that may cause instability or be abnormally pressurised. The Cement casing may be sealed with cement typically either Surface casing up to the base of the surface casing or all the way to the surface. Salt water zone r Production casing. A final wellbore is drilled into the target rock formation or zone containing shale gas. Once fractured, the shale gas produces into Intermediate casing the well. This wellbore is lined with a production Cement casing that may be sealed with cement either to a safe height above the target formation up to the base of the intermediate casing; or all the way to the surface, depending on well depths and local geological conditions. Cement Production casing Production Zone24 Shale gas extraction in the UK: a review of hydraulic fracturing