Shale gas in the United Kingdom

Areas

The Department of Energy and Climate Change (DECC) originally identified large areas of eastern and southern England as having the "best shale gas potential":

The main area identified runs from just south of Middlesbrough in a crescent through East Yorkshire, Lincolnshire, Northamptonshire, Buckinghamshire and the Cotswolds to Somerset and Wiltshire. It then turns along the South Coast and Downs, including most of Dorset, Hampshire, Sussex, Surrey and Kent. Shale gas sites are under investigation in the Sussex commuter belt, near Haywards Heath, the Mendip Hills, south of Bath, in Kent, Lincolnshire, south Wales, Staffordshire and Cheshire, as well as more sites near the existing find in Lancashire.

However the British Geological Survey report released in October 2014 said that there was little potential for shale gas in the Weald Basin as the field has not yet reached thermal maturation, however may exhibit oil-shale potential. (see 'Weald Basin' below)

Bowland Basin

As of June 2013, the Bowland Basin was the only area in the UK where wells have been drilled specifically for shale gas. Four wells have been drilled by Cuadrilla Resources, and one by IGAS Energy. None of the wells have produced gas.

Cuadrilla started drilling Britain's first shale gas exploration well, the Preese-Hall-1, in August 2010. The well penetrated 800m of organic-rich shale. The company hydraulically fractured the well in early 2011, but suspended the operation when it triggered two seismic events of magnitudes (M_L) 2.3 and 1.5, the larger of which was felt by at least 23 people at the surface. Work on the well stopped in May 2011, and the government declared a moratorium on hydraulic fracturing that was sustained until December 2012, subject to additional controls to limit seismic risk.

In September 2011, Cuadrilla announced a huge discovery of 200 trillion cubic feet (tcf) of gas in place under the Fylde Coast in Lancashire. Cuadrilla stated that it would be happy if it could recover 10–20% of the gas in place. Lord Browne ignored this latter point in media interviews, claiming that the Lancashire discovery could satisfy the UK's gas consumption "for 56 years", with similar, sensational media reports claiming that the find was "so rich it could meet Britain's needs for decades", or that it had "the potential to do more for Lancashire than the cotton industry." (For comparison, the cotton industry in Lancashire employed, at peak penetration in 1811, 37% of the county, or about 70,000 people; Cuadrilla believes fracking will create 1,700 jobs in Lancashire, current population 1.1m). The British Geological Survey—responsible for producing inventories of the UK's mineral resources, and far more cautious in its estimates—felt prompted, however, to re-evaluate its projections in light of the find, which Cuadrilla believes could provide 5,600 jobs in the UK at the peak of production. Industry estimates suggest shale gas in Lancashire alone could deliver £6bn of gas a year for the next three decades.

In July 2013, Cuadrilla applied for a permit to hydraulically fracture its previously drilled well at the Grange Hill site. In April 2014, Cuadrilla published news of their continuing consultation with residents shale gas exploration sites in the Fylde.

In 2011 and 2012, IGas Energy drilled a deep well to evaluate shale gas, and found gas shows in the Bowland Shale, with total organic content averaging 2.7%. The formation was reported to be thermally mature, in the wet gas window. IGAS bought large blocks of gas licences in 2011, much of which is reportedly prospective for shale gas.

IGas announced that it would drill a well to evaluate shale gas at Barton, near Manchester. Drilling would begin in October 2013, and take two to three months. IGas has not applied for a permit to hydraulically fracture the well.

Weald Basin

A BGS/DECC report from May 2014 indicates that there is little potential for shale gas fracturing in the Weald Basin, south of London. It does suggest that there is the possibility for the extraction of light tight oil from shales (LTO) Subsequent exploration showed a potentially major oil field near Gatwick Airport.

Northern Ireland

According to February 2013 reports from PricewaterhouseCoopers, there could be £80 billion in reserves in Northern Ireland, although these claims were criticised as being sensationalist.

National Parks

The Durham Energy Institute has examined the likelihood of drilling in National Parks. The parks with geologies of interest are the North York Moors, the Peak District, the South Downs and to the south of the Yorkshire Dales.

Resource estimates

According to a 2011 report of the Energy and Climate Change Select Committee, "Shale gas resources in the UK could be considerable—particularly offshore—but are unlikely to be a "game changer" to the same extent as they have been in the US, where the shale gas revolution has led to a reduction in natural gas prices." The Committee's chairperson, Tim Yeo, revised his personal opinion in 2012, however, and argued shale gas is a "game changer" that could "transform the UK's energy independence". Interest in fracking came just as imports of gas to the UK had surpassed domestic production in 2011 for the first time since the 1960s.

Estimating the size of recoverable resource is difficult due to the uncertainty of the usually small percentage of shale gas that is recoverable. In addition, companies may embrace large estimations of reserves to boost share prices. In the United States, companies had been subpoenaed in 2011 on suspicion that the projections they provided to investors, including press-release figures, were inflated. In 2012, national agencies in the U.S and Poland revised dramatically downward their estimates of shale gas resources.

Part of the problem in evaluation is also the uncertainty of decline curve analysis from early data: shale gas wells can fall off sharply during the first year or two, then level off to a slower decline rate; the shape of the curve, and therefore the ultimate recovery, is difficult to predict from early production rates.

Before drilling, IGas estimated gas in place of 4.6 Tcf in the Ince Marshes site, though it was unlikely that more than 20% of it could be recoverable; After drilling their first well, IGas announced that the estimated gas in place was at least double their previous estimate.

In early 2012, Celtique Energie estimated that there might be as much as 14 Tcf of recoverable reserves in countryside south of Horsham, West Sussex. Preliminary estimates in 2011 suggested that there may be £70bn worth of shale gas in South Wales, and 1.5bn bbl oil equivalent in Northern Ireland according to a report by PwC.

British Geological Survey

In June 2013, the British Geological Survey estimated the gas in place within the Bowland Shale of central Britain to be within the range of 822 TCF to 2281 TCF, with a central estimate of 1,329 trillion cubic feet (37,600 km³), but did not estimate how much of the gas was likely to be recoverable, and cautioned:

"Estimates of the amount of recoverable gas and the gas resources are variable. It is possible that the shale gas resources in UK are very large. However, despite the size of the resource, the proportion that can be recovered is the critical factor."

Industry estimates were that about 10% of gas in place could be extracted. 130 TCF would supply Britain's gas needs for about 50 years.

Comment from the British Geological Survey suggested even more substantial shale gas reserves offshore.

US Energy Information Administration

In June 2013, the US Energy Information Administration issued a world-wide estimate of shale gas, which included an incomplete estimate of recoverable shale gas resources in the UK. The Carboniferous shale basins of North of England and Scotland, which include the Bowland Basin, were estimated to have 25 trillion cubic feet of recoverable shale gas. The Jurassic shales of the Wessex Basin and Weald Basin of southern England were estimated to have 600 billion cubic feet of recoverable shale gas and 700 million barrels of associated oil. The agency noted that the UK shale basins are more complex than those in the US, and therefore more costly to drill. On the other hand, as of June 2013, the price of natural gas in the United Kingdom was reported to be more than double the price in the US and Canada by one source and three times higher by other sources.

Regulations

In 2012, a joint report by the Royal Society and Royal Association of Engineers (RS/RAE), commissioned by the government to identify the problems and advise regulatory agencies, emphasised that regulation "must be fit for purpose" with a focus on maintaining "regulatory co-ordination and capacity" and "the way in which risks scale up should a future shale gas industry develop nationwide." The government responded with a paper that outlined the requirements of the regulatory framework.

In January 2014, an impact assessment by the European Commission concluded that existing legal and regulatory environments for shale gas exploration and development were insufficient, and recommended a new directive with specific requirements for high volume hydraulic fracturing to address: "environmental risks and impacts"; allay "public concerns", and; "enable investments". In August 2016, the Environment Agency followed up their 2013 draft consultation with their final version on guidance for "flow testing and well stimulation, including hydraulic fracturing" for onshore operators in England.

Criticism

In 2012, the joint Royal Society and Royal Academy of Engineering report was critical of current regulation which failed to ensure independence of the well examiner scheme by ensuring that the well examiner was independent of the operating company. The government responded: "there are a few well operators who wish to use in-house examiners, and that option is legally open to them if they can fulfil the DCR (Design and Construction Regulations) requirements of an appropriate level of impartiality and independence from any aspects of the well design/construction/operation."(paraphrase this instead of using quote)

Climate change

Shale gas is largely methane, a hydrocarbon fuel. As such 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.

The 2008 Climate Change Act committed the UK to reducing CO2 emissions by 50% in 2030, and by 80% by 2050. Currently the UK is generating 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

In April 2014, the Intergovernmental Panel on Climate Change (IPCC) issued its 5th Assessment report. With regard to natural gas, and the shale gas debate, it states "GHG emissions from energy supply can be reduced significantly by replacing current world average coal‐fired power plants with modern, highly efficient natural gas combined‐cycle power plants or combined heat and power plants, provided that natural gas is available and the fugitive emissions associated with extraction and supply are low or mitigated (robust evidence, high agreement). In mitigation scenarios reaching about 450 ppm CO2eq concentrations by 2100, natural gas power generation without CCS acts as a bridge technology, with deployment increasing before peaking and falling to below current levels by 2050 and declining further in the second half of the century (robust evidence, high agreement)".

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"

Environmental impact

In 2012, the jointly published Royal Society and the Royal Academy of Engineering Shale Gas Review included recommendations on groundwater contamination, well integrity, seismic risk, gas leakage, water usage and disposal, management of environmental risk, implementation of best practice, with well integrity being "of key importance".

Groundwater contamination

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."

Contamination of groundwater by methane can occur after the abandonment of the well: "Gas and other contaminants may accumulate slowly in these cracks, enter shallow strata or even leak at the surface many years after production or well abandonment. Even the presence of surface casing provides no assurance against gas leakage at the surface from the surrounding ground."

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. 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 integrity

According to Professor Mair, who chaired the joint review by the Royal Society and the Royal Academy of Engineering, "well integrity is of key importance".

In the first UK shale gas well, Preese Hall 1, the cement bond log (CBL) showed some places with poor cement behind the casing in the lowest 100 feet of the well, between zones in the production hole section, which were repaired to achieve better zone isolation. Without repair, production would have been compromised, but not the integrity of the well.

The magnitude 2.3M coseismic slip of 1 April 2011 caused casing deformation in "the lower section of the reservoir productive zone" of the Preese Hall 1 well. Well "integrity was not considered a risk" "due to the "integrity of the casing, and the cement, in the upper completion", "confirmed by surface gas measurements and annular pressure readings".

Well leak concerns

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. Regulation calls for baseline monitoring to determine if any leak issues are related to the drilled well.

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.

In 2013, data from DECC was released concerning offshore and onshore well leaks from operating and abandoned wells and of the approx 2000 onshore wells, and approx 6500 offshore wells, the number of current recorded leaks is zero, although there was a need for two well integrity repairs.

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%).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.

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.

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 November 2013 paper states Well-integrity failure occurs when all barriers fail and a leak is possible. True well-integrity failure rates are two to three orders of magnitude lower than single-barrier-failure rates.. 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.

A research paper by Watson and Bachu 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%.</ref>

Use of radioactive sources

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.