Shale gas extraction: issues of particular relevance to

ea sac
European Academies’
Science Advisory
Shale gas extraction: issues
of particular relevance to the
European Union
Background and scope of this statement
Following the rapid increase over the past decade in the production of shale gas
in the USA1, political interest in Europe has grown on the local potential of gas
obtained by hydraulic fracturing of shale (‘fracking’)2. Potential attractions are
seen from the energy security, local economic competitiveness and (to a lesser
extent) employment standpoints, while the overall environmental advantages
and disadvantages remain a matter of debate. Public concern has been high,
with significant local opposition to attempts in a number of European Union (EU)
countries to conduct exploratory drilling, and in some countries (e.g. France) a
vote in Parliament on forbidding hydraulic fracturing by law. A number of EASAC
member academies have already completed reviews on the risks from shale
gas extraction and their management (see Royal Society and Royal Academy of
Engineering 2011; Académie des sciences 2012; acatech – German Academy
of Science and Engineering 2014; Lithuanian Academy of Sciences 2014; Polish
Academy of Sciences 2014; Swiss Academies of Arts and Sciences 2014).
On 22 January 2014, the European Commission adopted a non-binding
Recommendation for ‘Minimum principles for the exploration and production
of hydrocarbons (such as shale gas) using high volume hydraulic fracturing’
(European Commission 2014). Member States have been invited to implement
these recommendations within 6 months of publication and the Commission will
review the Recommendation’s effectiveness in July 2015. Recognising the public and
political interest in the issues around fracking and the underlying science, EASAC set
up an expert review group whose advice was discussed by EASAC Council in May
EASAC Council noted that scientific and engineering assessments are now
available from a number of science and engineering academies, both within Europe
(Royal Society and Royal Academy of Engineering 2011; Académie des sciences
2014; acatech – German Academy of Science and Engineering 2014; Lithuanian
Academy of Sciences 2014; Polish Academy of Sciences 2014; Swiss Academies
of Arts and Sciences 2014) and elsewhere (see, for example, International Energy
Agency 2012; Australian Council of Learned Academies 2013; International Risk
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Gas extracted from shale deposits through horizontal drilling and hydraulic fracture provides more
than 40% of US natural gas supply and is projected by the US Energy Information Administration to be
the dominant source of domestic gas for the foreseeable future (EIA 2014). Other unconventional gas
production in the USA (including coal bed methane and tight sediments) requires similar stimulation
methods so that total unconventional production requiring hydraulic fracturing is above 50% of total
US gas demand.
Although media coverage often uses the term ‘fracking’, this is shorthand for the term
‘unconventional gas extraction’, which requires ‘hydraulic fracturing’ to inject fluids into geological
formations to create and expand fissures, allowing the enclosed gas to be released and flow out of the
formation into the well bore.
Shale gas extraction | October 2014 | 1
Governance Council 2013; Council of Canadian Academies 2014). The most recent
of these incorporate data available up to the end of 2013. However, much of the
data and assessments are based on experience and evaluations outside the EU area.
This EASAC statement therefore focuses on three particular aspects that may require
special attention from a European perspective in seeking to harvest the economic
potential of shale gas reserves in the EU:
1. While some shale gas areas in the USA (e.g. Pennsylvania) have comparable
population densities to Europe, most of the areas studied to date in the USA,
Canada and Australia have much lower densities. Issues related to population
density may therefore be more significant in EU countries.
2. Since the EU has the world’s most comprehensive and legally binding greenhouse
gas (GHG) reduction and climate change mitigation policies, potential effects
of shale gas exploitation on meeting Europe’s climate change targets are an
important consideration, both for carbon dioxide (CO2) and methane emissions.
3. The EU public has already shown considerable sensitivity to the issue of fracking,
so effects on the public and on their communities are also critical issues.
This EASAC statement thus considers factors related to these three issues. It draws
on the reviews and assessments cited above, peer-reviewed literature since late
2013 and consultation with experts from EASAC member academies (Annex 1).
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Issue 1 Implications of Europe’s high
population density
The average population density of EU countries ranges
from just below 100 to over 600 people per square
kilometre, compared with just over 3 in Canada and
Australia, and 32 people per square kilometre in the
USA. It is thus inevitable that unconventional gas and
oil operations can interact closely with other activities
of society. Demands on, and values attached to, a
given area of land are also likely to be greater where
population densities are higher. Critical features
include the areas required for hydraulic fracturing
activities, the interactions (transport, noise, local
emissions, etc.) with other land users, and longerterm impacts on the area, including post-closure
reclamation. Since the zone reached by a single well
is limited, large-scale fracturing requires many wells
to be established, so potential impacts should be
considered on a cumulative basis.
Europe is not, however, starting from the beginning
in using hydraulic fracturing and horizontal drilling.
These technologies have been practised in Europe
since the 1950s and 1980s respectively. One European
company (Elf, now merged with Total) was a pioneer
in horizontal drilling. In the early 1990s, horizontal
drilling and multiple hydraulic stimulations were
successfully executed in northern Germany in
5000-metre deep wells to increase gas flows. 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
Regulations intended to ensure safe and
environmentally sensitive drilling activities are already
in force in those European countries with their own
oil and gas industry. In Germany, for example, no
hydraulic fracturing is allowed without prior proof
of the technical integrity of the well. International
Energy Agency (2012) guidance describes the key
environmental and social risks and how they can be
addressed, and suggests ‘Golden Rules’ necessary
to obtain the economic and energy security benefits
while meeting public concerns. Academy analyses
mentioned above also provide detailed guidance on
environmental, seismicity and safety issues. In the
UK review, the Royal Society and Royal Academy of
Engineering (2011) concluded that the health, safety
and environmental risks associated with hydraulic
fracturing can be managed effectively as long as
operational best practices are implemented and
enforced through regulation. Similar conclusions
emerge from other analyses (Académie des sciences
2012; International Energy Agency 2012; Australian
Council of Learned Academies 2013; International
Risk Governance Council 2013; acatech – German
Academy of Science and Engineering 2014; Lithuanian
Academy of Sciences 2014; Polish Academy of
Sciences 2014; Swiss Academies of Arts and Sciences
2014). The priority is thus seen as to apply existing
regulations adequately rather than produce new ones.
Nevertheless, studies such as that by the Council of
Canadian Academies (2014) and those of EASAC
experts draw attention to the limited information and
number of peer-reviewed studies that are available,
owing to the young age of the industry. Uncertainties
thus exist in assessing potential impacts at individual
sites that differ in their geology, hydrology, climate,
access infrastructure and socio-economic conditions.
Such uncertainties need to be taken into account
when setting priorities for monitoring, research and
regulation, as addressed later in this statement.
The scale of the potential for shale gas extraction in the
EU is also uncertain because of limited geological data
on the accessibility of gas (and oil) from the areas with
geological potential shown in Figure 1. The US Energy
Information Administration (EIA 2013) estimates
unproven technically recoverable shale gas volumes
in Europe to total 470 trillion cubic feet or 13.3 trillion
cubic metres, of which the largest are in Poland and
France (4.19 and 3.88 trillion cubic metres respectively).
The next largest reserves are thought to be in Romania
(1.44), Denmark (0.91), with the Netherlands and
UK both estimated to have 0.74 trillion cubic metres.
However, such estimates are based on limited data
and are thus very approximate; as more studies are
performed they will change—perhaps substantially. For
instance, since the EIA report, UK estimates have been
greatly increased in a British Geological Survey analysis
(Andrews 2013). In western Lithuania, significant
geological sources of unconventional oil and gas
have been estimated (at a technical recovery rate of
1%) to potentially provide 14 trillion cubic metres of
gas3 from an area of 2,700 km2. On the other hand,
only a fraction of the EIA estimates are considered
economically recoverable by the Polish Geological
Institute (referred to in International Energy Agency
The Lithuanian analysis (Lithuanian Academy of Sciences 2014) also identified barriers to exploitation as the limited information from
exploratory drilling; the high population density and lack of available land; past experience of low reclamation rates and the sensitivity of
public opinion; and incomplete regulation on environmental, safety and health issues.
Shale gas extraction | October 2014 | 3
Figure 1 Unconventional gas resources in Europe (source: International Energy Agency 2012).
2012). The supposed presence of gas in the Paris basin
has also been subsequently shown not to exist.
The geology of much of Western Europe is also
more complicated than in parts of the USA. Older,
more fractured formations are characteristic of many
European countries and this has implications for the
technical and economic viability of gas extraction. To
determine the proportion of gas in place that can be
extracted, flow rates must be analysed from test wells.
Moreover, non-geological factors including costs,
engineering, supply chain and access restrictions will
determine the commercial scale of shale gas extraction.
These uncertainties make it difficult to follow the
EU Commission Recommendation that Member
States ensure that ‘the geological formation of a site is
suitable for exploration of hydrocarbons using
high-volume hydraulic fracturing’. With no established
criteria that can be used to verify ‘suitable’, the
governing criteria will probably be the economic value
of the site based on sales prices and estimates of total
costs (including taxes), while recognising remaining
uncertainties on the size of the gas resource and
extraction (including regulatory compliance) costs. The
main parameters can only be determined by a phased
approach with exploratory drilling in combination with
application of stimulation technologies in order to
determine commercial viability.
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The EIA estimates for shale gas in Europe can be
compared with the USA’s 567 trillion cubic feet (16
trillion cubic metres) estimated in the same study
(EIA 2013) to suggest per capita reserves of around
half those in the USA. The European Commission’s
Joint Research Centre (JRC) review of unconventional
gas (JRC 2012) concluded that the potential
significance of shale gas for the EU market would
probably be much less than had been observed in
the USA and that ‘the best case scenario for shale
gas development in Europe is one in which declining
conventional production can be replaced and import
dependence maintained at a level around 60 %.’
Nevertheless in the current heightened concerns over
the geopolitical implications of reliance on imports
from Russia, indigenous supplies of shale gas could
make a valuable contribution to energy security by
avoiding increased dependence on imports from such
potentially disruptable sources. Import substitution
is thus an important consideration when judging the
merits of allowing shale gas exploration in Europe.
Increasing local production of gas in Europe rather
than importing more gas also has the benefits:
•• the rules and standards for safe and clean
operations and their enforcement are set within
EU borders and controlled by EU Member States;
Figure 2 Innovation in well design and operation (source: Range Resources Ltd.). Left: old single well spacing
(Texas); right: modern multi-well cluster configuration accessing gas from an area of up to 10 km2 (Pennsylvania).
•• the energy use and methane leakage associated
with the transport of gas to Europe over long
distances (up to 4000 km) from Siberia and Algeria
is reduced.4
A comparison of old and current technologies is
shown in Figure 2.
Rather than revisit the analysis of health, safety and
environmental aspects already covered extensively in
the documents cited above, this EASAC statement
focuses on the spatial conflicts that may emerge when
drilling and hydraulic fracturing are introduced into the
more populous and high-land-utilisation countries of
the EU. Shale gas development involves the same mix
of construction and industrial activities as conventional
gas development, but has historically been at a
higher intensity because (1) the resource covers large
geographical areas (see, for example, Figure 1), (2)
production declines quickly requiring new horizontal
wells to be drilled to keep production stable and (3)
individual shale gas wells may need to be spaced closer
together to drain the reservoir efficiently, owing to the
rock’s lower permeability.
The reservoir volume accessed from a single site
has increased substantially through such multiwell pads and longer horizontal laterals, offering
a potential extraction area of 10 km2 or more
from one pad and reducing surface land use area
accordingly. Unconventional gas fields thus no longer
have significantly higher well pad densities than
conventional fields. Technically, horizontal wells with
a reach of up to 12 km are possible (although such
wells would at present be uneconomic), but even
with clusters of only 3 km radius, it becomes viable
to produce unconventional gas in heavily populated
areas5. This is a key contribution to reducing impacts
in Europe, and investors and operators should be
motivated to apply best practice to reduce concerns
over land use demands. This reduction in land use
burden also reduces the challenges of land reclamation
after use and associated post-closure financial liability.
In terms of land impacts, it is the well pad size and
spacing that is significant. Areas of shale gas-well pads
(1.5–3 hectares) tended to be larger than conventional
gas pads. Moreover operations in some US gas fields
initially had a well density of as high as one well per
0.8 km2 after 13 years of development, and intensive
development thus required significant displacement
of land to shale gas activity. However, shale gas wells
are no longer drilled as single wells but as part of a
cluster with as many as 20 wells or more per cluster.
In addition to land for well pads and ancillary facilities,
shale gas development also requires large amounts
of water (95% of the fracking fluid), proppants for
hydraulic fracturing (~5%) and chemicals constituting
usually less than 1% of the fracking fluid. The most
common proppant is sand, and hydraulic fracturing
in oil and gas operations has led to a large increase
in sand mining in the USA (some 28.7 million tons in
2011). The availability and location of the sand (high
quartz content and round, 100–500 micrometre
Such advantages were also emphasised in a recent UK Parliamentary Assessment of the potential for shale gas (House of Lords Economic
Affairs Committee 2014).
For example, for a medium-sized city such as Zurich, virtually all of any gas under the city could be accessed from a single central
Shale gas extraction | October 2014 | 5
size grains are required) from quarries, near-shore
or coastal sources are thus potential issues. Current
trends to manufacture proppant grains artificially (e.g.
via ceramics) are a potential means of reducing such
The large quantities of water required make this a
sensitive issue in areas where existing supplies are
already highly utilised; there may be a particular
problem in meeting water demands in dry countries
(or regions, or periods) because of competition with
agriculture, urban supply and other (e.g. industrial)
uses. The water used is turned into a pressured fluid
containing sand and chemicals, and will also release
gas and other minerals when it returns to the surface.
Migration to nearby aquifers needs to be avoided
and any contaminated water that returns (flow-back
water) appropriately treated. Detailed guidance on
these aspects has been given in the academy reviews
already cited and will not be repeated here. In general,
part or all of the flow-back water can be recycled
and net water consumption reduced. Moreover, in
some areas, water can be extracted from non-potable
resources to avoid competing with potable water
resources. Nevertheless, in areas of limited water
supply, water demand could limit where, when and
how fast shale gas can be developed. In response to
this, alternative techniques using non water-based
hydraulic fracking fluid have been developed—for
example propane-based fracking fluids6.
With regard to water quality, public concerns over
potential water contamination are high, so proposals
for shale gas extraction should evaluate thoroughly the
potential effects on local and regional hydrogeology,
and potential long-term, long-range groundwater
impacts. Fracturing of shale formations forms fissures
which open new water transport routes, and can thus
affect flows and chemical composition of surrounding
waters. In particular, black shales are generally rich in
trace metals and often in sulphides (notably pyrite)
so a change in the chemical composition of the
deeper waters in contact with the shale cannot be
avoided (this may affect pH as well as concentrations
of trace elements). At the usual depths of fracking,
directly affected groundwater is not of drinking water
quality; most are undrinkable brines with a higher
specific gravity so that they would not normally mix
with the shallow and lighter potable groundwater.
However, there are conceivable situations in which
hydraulic fracturing could affect potable waters. Firstly,
fracturing operations at shallow depths have been
suggested in which case direct impacts are possible.
Secondly, though geologically unlikely, the possibility
See, for example,
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of vertical transport between different depths through
overpressures or major pathways such as permeable
faults should be considered, and a thorough
geological characterisation performed of the reservoir
and its overburden to map any geological faults that
could provide connections between distant layers.
Up to now, effects on groundwater that have
occurred have been caused by poor well integrity or
cementation, or deficient handling at the surface.
Thus, as emphasised later in this statement, securing
a correct well design and regularly checking its
integrity are critically important. Clearly, groundwater
composition should be included as one of the
baselines that should be monitored at the start,
during operations and after they have concluded.
Additional monitoring of deeper non-potable aquifers
(located close to the shale but far from the potable
water table) can allow early detection of any possible
contamination source and provide time to respond.
In one location in Poland, fracking operations led to
drinking water from a well becoming muddy, which
led to fears of contamination by the chemicals used
while fracturing. However, investigations showed that
the origin was vibrations from water pumps which
caused mud to suspend in the water. Such physical
interference with local water supplies should thus also
be considered. Guidance on these aspects has been
published in the cited academy reviews.
With regard to potential interference with
communities and their lifestyles, shale gas extraction
requires energy to power the drill rigs and pumps,
etc., and vehicles and infrastructure to access the
sites. Transport of equipment, chemicals, water,
construction materials, and workers, often in large
vehicles, will be needed at various stages. Sources
of noise include drilling and hydraulic fracturing
equipment, natural gas compressors, traffic, and
construction. Drilling and completing a well is a
24-hour operation, so lighting can also be an issue.
Drilling a shale gas well typically takes 4–5 weeks
and, as multiple horizontal wells may be drilled
sequentially from the same pad, this may extend the
period to several months. Because hydraulic fracturing
requires more pressure and water, more pumps and
other noise-producing equipment may be used than
in a conventional well. Practices developed in lowpopulation-density locations may need rethinking to
redefine the work-flow to minimise overall disturbance
and environmental impact—for example by starting
with the building of shared infrastructures before
deploying the drilling process.
Restoring a well site after the gas has been extracted
is an important part of the overall process. It includes
capping and sealing7 the well, removing equipment,
and performing necessary remediation and restoration
to the subsequent land use (which may differ from the
pre-drilling use). Historically in the USA (for all types
of oil and gas extraction), the reclamation rate has
been only 41% that of the abandonment rate, and
there were over 50,000 uncertified abandoned wells
at the end of 2012, although many of these were from
earlier technologies that would not be used in Europe
(see Figure 2, left), and abandonment and reclamation
regulations in Europe should prevent similar problems.
More modern multiple sites (Figure 2, right) are of
much smaller total area and thus less of a logistical and
economic challenge for restoration.
Finally, there is an important difference between
the USA and Europe in land mineral rights. Owning
private land in the USA includes ownership of any
hydrocarbons underneath, which can thus create
revenues from gas production to the landowner. In
Europe, according to existing mining laws, ownership
is with the state so that landowners and communities
do not get the compensatory financial benefits
found in the USA. Revision of mining law is, however,
underway in some EU countries; for instance in
France new fiscal regimes will be introduced with
the twin objectives of dedicating part of the shale
gas exploitation benefits to local communities, and
introducing environmental protection aspects into the
permitting process.
The US system has the advantage that financial
interests of the landowner and shale gas extractor are
aligned. The European model of state ownership of
the underground has the advantage that horizontal
drilling that crosses surface property boundaries is
not affected. Such horizontal drilling has reached
6–10 km in some industry experiments, considerably
increasing the area of the underground resource
that can be reached from a single cluster pad to
30–100 km2.
This present difference between the existing legislation
in the USA and in Europe can lead to fundamentally
different general public and individual attitudes to
the inconvenience and potential risks of shale gas
development. While this is a legal or political issue,
the extensive literature on perception of risk shows
the critical importance of the presence or absence
of individual benefits in influencing an individual’s
perception, and acceptance, of risk.
In relation to issue 1, EASAC identifies a number of key
Applying existing best practice:
•• maximise the horizontal wells drilled from the same
pad (cluster drilling);
•• establish strict well completion and land restoration
rules with the necessary enforcement regimes and
associated financial liability in the event of failure to
meet restoration standards;
•• establish standards for the long-term sealing of
shale gas wells and the methods required to control
sealing quality;
•• apply low noise and disturbance technology and
•• recycle flow-back fluids to reduce water use and
•• disclose additives used.
Research and development needs to include the
•• technologies that minimise the environmental
impact of hydraulic fracturing;
•• technologies for better characterising and
assessing the resources, including their spatial
•• the acquisition of baselines for potable aquifers
before any production starts8;
•• technologies for monitoring and detecting in
advance any deviation from expected behaviour;
•• advanced technologies (such as use of coiled tubing,
smart completion systems) for reducing drilling
and production environmental impacts both at the
surface and down-hole;
To ensure final sealing of the well, it may be necessary to remove at a selected depth the casing and cementation of the well over
a limited length, and replace it with a plug of clay and cement which will provide a stable corrosion-resistant plug to ensure long-term
tightness of the seal.
Groundwater in many areas contains substantial levels of natural methane (for example, of 22 geothermal wells drilled in recent years in
Holland, 20 have intercepted strata that contained groundwater with substantial natural amounts of methane, requiring the installation of
gas separators).
Shale gas extraction | October 2014 | 7
•• alternatives to high-volume (water) hydraulic
fracturing using either alternative fluids or
alternative processes (including increased recycling
of flow-back fluids).
Issue 2 Climate change policies
The EU has legally binding GHG reduction policies9
to address the threat of global warming. Shale gas
is often cited in the public debate as offering the
potential to reduce EU GHG emissions more efficiently
(on the assumption that less coal or other highcarbon-energy sources would be used) and potentially
providing economic leeway for more ambitious
GHG reduction targets in the short to medium term.
However, the volume of methane emissions from
gas leakage at the wellhead and in the distribution
system is a critical factor in view of methane’s global
warming potential10 (GWP) being much higher than
that of CO2. In this context, the critical importance of
timescale to methane’s contribution to global warming
may not be fully appreciated by policymakers. The
commonly quoted GWP for methane is from the
assessment of IPCC (2007), where the GWP is given as
25 (effect over 100 years). However, the assessment
of IPCC (2013) increases methane’s GWP to 34 (100
years), and calculates the GWP for the first 10 years
after emission is 108, and 86 for the first 20 years after
Which GWP value should be used is influenced by
the international consensus that average global
temperature should not rise to more than 2.0 °C
above pre-industrial levels, because of the high risk of
triggering ‘runaway’ warming from feedbacks such
as release of natural GHGs (particularly methane)
from stores in permafrost and deep oceans. With
current warming already approaching approximately
1 °C, current trends have this ‘dangerous climate
change’ state reached in a few decades, not a century
(IPCC 2013). It is thus argued that the contribution
of additional GHGs with a high GWP should be
considered over short (10–20 year) periods rather
than the 100 years used in earlier assessments
(Shindell et al. 2012); in other words, the GWP of
methane should be considered as 86–108 that of
CO2. When considering any ‘trade-off’ between
methane and CO2 therefore, short-term increases in
methane can outweigh even a substantially larger
reduction in CO2.
While these re-evaluations of methane’s GWP are
not related to any particular source of methane, they
do increase the significance of methane emissions
from any source. In this respect, analyses from the
USA reveal a consistently higher level of methane
in the atmosphere (from direct measurements
from aircraft, towers, etc.) than would be expected
from bottom-up calculations based on presumed
emissions from resource extraction and the gas and
oil transportation and distribution network (see, for
example, Brandt et al. 2014; Caulton et al. 2014).
Research suggests that these ‘extra’ emissions include
leaks from abandoned wells, a small number of
large leaks at well sites (termed ‘super-emitters’), the
infrastructure of gas processing plants, storage and
compressor facilities, as well as from the huge (and
in many cases old) transportation and distribution
system. Some authors (Barcella et al. 2011; Molovsky
et al. 2011; Allen et al. 2013; Williams 2013) conclude
that hydraulic fracturing is not a substantial emissions
source relative to current national totals; nevertheless,
such large differences between field measurements
and emissions inventories can and should be better
understood to allow efforts to reduce methane
emissions to be properly prioritised.
At GWPs of 86–108, it is clear that the potential
climate ‘benefit’ of natural gas relative to coal is
highly sensitive to methane emissions. The US
Environmental Protection Agency currently assumes
a 1.5% leakage rate in natural gas extraction and
production, but recent studies (Brandt et al. 2014;
Caulton et al. 2014; Miller et al. 2014) suggest fugitive
emissions in the USA may be considerably higher.
This remains contested, however, with other studies
(for example, Barcella et al. 2011) that suggest flaws
in the EPA’s methodology that fail to reflect current
industry practice and overstate emissions. One of
the recent studies (Allen et al. 2013), based on direct
measurements of methane emissions at 190 onshore
natural gas sites in the USA, also found total methane
emissions from natural gas production lower at
approximately 0.42% of gas production. It should
be noted that German upstream industry is reporting
approximately 0.02% of methane emissions from
natural gas production (Ziemkiewicz et al. 2014),
indicating that significant methane emissions can be
avoided with appropriate regulations11.
Owing to current uncertainties over methane
emissions, the simple claim that natural gas is always
The EU is committed to transforming Europe into a highly energy-efficient, low-carbon economy. For 2020, the objective is to cut GHG
emissions to 20% below 1990 levels; for 2050, the objective is to reduce by 80–95% compared with 1990 levels.
Global warming potential expresses how much a greenhouse gas traps heat in the atmosphere relative to CO2 (assumed to be 1).
Methane is also released by coal mining (coal bed methane) and its handling varies between countries. In China, for example, methane
is released to the atmosphere; in Germany it is collected and used for heating.
8 | October 2014 | Shale gas extraction
better than other fossil fuels, and of gas being a
‘bridging fuel’ to a low carbon economy, is under
scrutiny in the USA (see, for example, Howarth et
al. 2011; Trembath et al. 2013; Brandt et al. 2014;
Howarth 2014; Newell and Raimi 2014), with
competing claims about the contribution of shale gas
extraction to reported methane emissions. A recent
meta-analysis (Heath et al. 2014) of the scientific
publications on this issue came to two conclusions:
(1) that emissions from shale gas extraction are
similar to those from conventional gas extraction
and (2) that both when used in power generation
would probably emit less than half the CO2 emissions
of coal. Nevertheless, the analysis also noted that
higher assumptions on fugitive emissions ‘may lead
to emissions approaching best-performing coal units,
with implications for climate change strategies’.
Regarding potential sources of emissions from shale
gas extraction, flaring and venting in conventional
exploitation in Europe ceased during the 1990s
(with the exception of initial flow tests in successful
exploratory drilling); industry therefore possesses the
necessary expertise to avoid this problem. ‘Green’
completion technologies are also widely used to capture
and then sell (rather than vent or flare) methane and
other gases emitted from flow-back water (they can
be recovered at low cost by taking out the gas within
a confined separator). This will be mandatory for
hydraulic fracturing of all gas wells in the USA from 2015
onwards. Ensuring ‘green completion’ is fully applied in
Europe is thus an essential prerequisite for maximising
benefits from shale gas to climate change policies.
Critical to eliminating methane emissions during well
construction and production is to ensure ‘wellbore
integrity’. This is accomplished by placing casing and
tubing into boreholes, which are sealed towards the
rock by cement12. Figure 3 shows the main elements of
a properly designed and constructed well (Royal Society
and Royal Academy of Engineering 2012). General
industry practice in conventional wells (which typically
have higher pressures and gas flow rates and longer
lifetimes than shale gas wells) has solved the problems
of gas migration. By pressure testing, the tightness of
the well can be verified. Hydraulic fracturing also uses
external casing packers to separate individual fracked
zones from each other, creating mechanical barriers in
the lowermost part of the well against gas migration
outside of the casing. Regulations have to make
Figure 3 Cementing and wellbore integrity
(source: Royal Society and Royal Academy of
Engineering (2012)).
sure that proper monitoring systems13 (during well
construction, stimulation, production phase and after
abandonment) are performed.
Poor well design has been the (most likely) reason
for methane emissions in the vicinity of gas wells in
Pennsylvania, which have been assigned by some to
shale gas wells and fracking (Ingraffea et al. 2014).
Further analysis (Molovsky et al. 2011; Williams 2013)
has shown that even before drilling for shale gas,
methane emissions had been observed in deeper
water wells. Shale gas wells penetrated and bypassed
these shallow gas zones, but were not designed for
proper isolation of these intermediate gas zones.
This appears to have allowed gas originating from
uncemented layers to migrate upwards outside of the
casing and reach the surface.
When no longer economical, the well is ‘abandoned’
using procedures long established in the industry.
Well integrity is also an issue for groundwater protection since while the fracking itself generally takes place below the groundwater
reservoir, well casing failure closer to the surface can result in groundwater pollution.
Monitoring the tightness of the annulus (the space between casing–casing or casing–rock) can be achieved through several (mostly
indirect) indicators: e.g. cement bond logging after cementing, pressure testing before fracking or production starts, monitoring annulus
pressure and temperature, gas sampling for gas quality and source.
Shale gas extraction | October 2014 | 9
The well is plugged with cement to shut off previous
producing zones, prevent emissions and protect
groundwater. As with the construction and production
phases, it is critical that these steps be implemented
effectively and that cement does not degrade over
time. The long-term integrity of well sealing still needs
further technological development. Firstly, in respect
of the method to be used—one option being the
removal of casing and cement over a specific length of
the well bore (at a depth selected below any aquifer)
by drilling out the casing, and sealing with clay and
cement in contact with a tight geological formation.
Secondly, further research is also desirable on cement
deterioration and on improved cementing materials to
increase further effectiveness and durability of sealing
on abandonment.
The importance of minimising methane emissions
has been recognised in the evaluations by the
science academies already cited. These emphasise
that appropriate regulations and standards should
be applied and well integrity secured by proper well
design and drilling/completion procedures, including
down-hole logging to detect whether cementing
of the casing is effective. Monitoring arrangements
should be applied to detect any well failure as early
as possible and continue after closure. Europe should
ensure a high degree of elimination and minimisation
of emissions in its shale gas policies and regulations.
Socio-political factors related to interaction with other
energy sources are also relevant to climate change
policy. For example, the financial resources invested in
shale gas will have to be retrieved, which could reduce
the capacity (or willingness) of the financial community
to invest in renewable energies such as solar or wind.
One (not peer-reviewed) assessment (Tyndall Centre
2011) calculated that investment in shale gas could
displace both offshore and onshore wind investment
in the UK through such competition for investment
resources. This led the UK House of Commons Energy
and Climate Change Committee (2011) to conclude
that lower gas prices driven by shale gas development
could extend the economy’s dependence on fossil
fuels, thus ‘contributing to locking in to high carbon
Such concerns may not apply to all EU countries since
some, including France and Germany, use very little
gas to generate electricity. In such cases, shale gas
would just replace conventional gas imported for use
in heating, with no interference with decisions related
to electricity generation. Moreover, estimates of likely
shale gas prices do not suggest that European supplies
will significantly affect market prices (JRC 2012).
EASAC experts thus comment that increasing supplies
of shale gas may just displace imports and have limited
10 | October 2014 | Shale gas extraction
impact on the energy balance. Furthermore, benefits
from shale gas exploitation could be partly reinvested
in improving renewable energy efficiencies: the option
thus exists for governments to offer reassurance
that shale gas exploitation would not weaken their
renewable energy priorities, or even reserve shale gas
taxation income to adhere to road maps towards low
carbon energy.
EASAC thus concludes that the accuracy of claims
that shale gas will mitigate global warming depends
on factors ranging from the nature and quality of
the extraction process to wider interactions with the
energy system. The following issues are relevant:
•• ‘green’ completions should be standard operating
procedure; in particular, operational requirements
should avoid open-air water disposal and require
confined separation devices which recover
hydrocarbon gases in flow-back operations;
•• regulation needs to have a routine focus on
‘well integrity’ based on thorough planning and
execution of the well, the completion phase
(including hydraulic fracturing) and during later
production and abandonment;
•• monitoring arrangements should be applied to
detect possible well failure and emissions from
surface processes as soon as possible;
•• in response to concerns over possible effects on
renewable energy policies, governments should
clarify the interaction of their shale gas policies and
their plans related to research, development and
implementation of low carbon renewable energy.
Issue 3 Public acceptance of shale gas
Whether in academy studies or parliamentary
enquiries, public acceptance is seen as a fundamental
precondition for large-scale shale gas development.
This will not be gained through industry claims of
technological prowess or through government
assurances that environmental effects are acceptable.
It requires trust to be built in the industry and the
regulatory system under which it operates, as well as
transparent and credible monitoring of environmental
impacts. Critical factors include issues related to the
industry’s ‘social license’, the environmental and other
risk management systems applied, and transparency
and access to relevant information.
The concept of ‘social license to operate’ is relevant to
the resources industry. Central to the concept of social
license to operate is the proposition that, even if fully
compliant with laws and regulations, activities that are
particularly intrusive or perceived to carry significant
risks can be vetoed by a hostile public through
campaigns, legal actions, demonstrations or other
democratic pressures. Such industries must negotiate
a ‘social license’ with their community to conduct their
business. In the case of shale gas this requires that
(Council of Canadian Academies 2014):
1. Communities and other stakeholders have an
informed understanding of the technologies of
shale gas production and the associated risks,
impacts and potential benefits; they are also
informed about the management and regulatory
processes that are used to manage these risks.
2. Proponents and regulators of these technologies
have an informed understanding of, and
demonstrate respect for, the concerns and
perspectives of various stakeholders.
3. Different parties are able to engage in constructive
dialogue with each other and work towards
agreed outcomes, or at least an accommodation of
It is also important that communities see how they
can benefit directly from production activities (as
mentioned in issue 1).
A critical factor is that stakeholders understand
and regard as acceptable the philosophical basis on
which regulations are based. In the case of the EU
Recommendation, a number of terms are used. For
instance, the concept ‘best available technique (BAT)’
is used (e.g. ‘The risk assessment should be based on
the best available technique’). ‘BAT’ is also applied in
the context ‘anticipate the changing behaviour of the
target formation, geologic layers … etc’, or establish
‘a minimum vertical separation’. However, ‘BAT’, while
including valuable flexibility to adapt to improving
technology, is vague in terms of the precision with
which such effects can be determined. Alternatives
used in some Member States include ALARP (as low
as reasonably practicable), which leaves much of
the detail to agreement between the industry and
regulators. Such approaches leave uncertainties in the
minds of stakeholders; trust in the regulatory process
is thus very important.
Other requirements in the EU Commission’s
Recommendation (e.g. ‘A site should only be
selected if the risk assessment … shows that the
high-volume hydraulic fracturing will not result in
direct discharge of pollutants into the groundwater’)
may also be difficult to fulfil owing to inherent data
limitations. The concept of ‘risk assessment’ is used
widely in the EU Recommendations in preference
to the alternative method of ‘environmental impact
assessment’. Risk assessment is based on estimates
of risk, which includes uncertainties, statistics and
probabilities, etc., whereas environmental assessment
can be seen as assessing the consequences and
results following certain actions or events (and
what measures can be taken to avoid any harmful
effects). Environmental assessment may also need
to capture the social and environmental context of
fracking (e.g. issues of landscape quality, impact
on tourism and water resource management).
The concept of ‘environmental risk assessment’
to define any consequences and environmental
effects is recommended by some academies. To
boost trust in the process, such assessments should
allow stakeholders to participate in the framing of
environmental problems; identifying and assessing
risks; and evaluating different means of managing
them (Royal Society and Royal Academy of
Engineering 2012).
Objective assessment of the environmental impacts
of shale gas development has also been hampered
by a lack, up to now, of adequate characterisation,
monitoring, and study. To understand better the risks
to surface water and groundwater resources at the
watershed scale, it will be necessary to develop and apply
effective baseline and operational monitoring. In the face
of development with incomplete knowledge, an adaptive
monitoring and management philosophy emphasising
transparency would identify any unanticipated impacts as
soon as possible (Rahm and Riha 2014).
Establishing a ‘comprehensive baseline’ is of utmost
importance. Such baseline studies are essential, not
least to enable the sources of any contamination to be
properly attributed. In Pennsylvania and Switzerland,
for example, studies (see, for example, Molovsky
et al. 2011; Ziemkiewicz et al. 2014) revealed that
methane very commonly occurs as a natural substance
in groundwater. Such studies should also characterise
the shale to identify other components (e.g. trace
metals) that may be released and affect the near-field
as well as far-field environment. As emphasised in
issue 2, to detect potential leakages of gas, operators
should monitor potential leakages of methane or
other emissions to the atmosphere before, during and
after shale gas operations, and such data should be
submitted to the appropriate regulator.
EASAC recommends that detailed and precise
information on water consumption and chemicals
used and discharged to the environment should be
available to regulators, so that they are in a position
to provide correct information to the public and
Shale gas extraction | October 2014 | 11
recognised interest groups14. Independent oversight
is of great importance, especially in the area of water
quality and quantity. A public monitoring network
(available via the Internet) could be used to provide
independent information on the impact of the shale
gas industry. Establishing methods to monitor the
environment and the creation of a monitoring network
should involve the public. Companies should also
engage with local communities to mitigate the impact
of their work.
Public reaction may also be influenced by the degree of
formal liability related to activities and actors. The low
historical reclamation rate in the USA mentioned above
supports Europe’s general approach that operators
provide a financial guarantee to cover post-closure
A final comment
Current concerns over heavy reliance on imports of
gas from Russia have increased further the attraction
of indigenous supplies of shale gas to limit import
dependence and contribute to energy security. This
EASAC analysis provides no basis for a ban on shale
gas exploration or extraction using hydraulic fracturing
on scientific and technical grounds, although EASAC
supports calls for effective regulations in the health,
safety and environment fields highlighted by other
science and engineering academies and in this
statement. In particular, EASAC notes that many
of the conflicts with communities and land use
encountered in earlier drilling and hydraulic fracturing
operations based on many single-hole wells have been
substantially reduced by more modern technologies
based on multiple well pads, which can drain up to
10 km2 or more of gas-bearing shale from a single pad.
Other best practices, such as recycling of flow-back
fluid and replacement of potentially harmful additives,
have greatly reduced the environmental footprint of
‘fracking’. Europe’s regulatory systems and experience
of conventional gas extraction already provide an
appropriate framework for minimising disturbance
and impacts on health, safety and the environment.
This analysis, however, also shows that while shale gas
may have significant global potential, it is no simple
‘silver bullet’ to address energy security and climate
change. Indeed, the scale of the resource itself and
the economic viability of its extractions in different
Member States remain uncertain. Without exploratory
drilling, this uncertainty will continue.
Claims that shale gas exploitation would contribute to
a net reduction in the warming from GHGs are largely
based on the possibility of replacing coal in power
generation by gas or of expanding gas use in transport.
Such environmental benefits can, however, only be
achieved through avoidance (or, where not possible,
minimisation) of methane emissions at all stages—from
the initial drilling, through the production phase and
into the future after the well is closed and abandoned.
To receive public acceptance, trust is critically important.
Trust will in the end only be built by real projects,
which prove the soundness of the technology and the
reliability of the operations and operators. Through
such projects, innovation based on empirical evidence
and expertise can adapt and improve processes for the
EU environment. Pilot projects need to be performed in
Europe to demonstrate and test best practice methods
and allow careful monitoring by the authorities.
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Annex 1 EASAC academy-nominated
experts for this study
Professor Bert Allard, School of Science and
Technology, Örebro University, Sweden
Professor Dietrich Borchardt, Department
Aquatic Ecosystem Analysis and Management,
Technical University Dresden; Helmholtz Centre for
Environmental Research, Germany
Dr Peter Burri, Swiss Association of Energy
Geoscientists, Basel, Switzerland
Professor Algimantas Grigelis, Branch of Biology,
Medicine and Geosciences, Lithuanian Academy of
Sciences, Vilnius, Lithuania
Professor Christian Growitsch, Hamburg Institute of
International Economics, Germany
Dr Francois Kalaydjian, IFP Energie nouvelles, RueilMalmaison, France
Professor Robert Mair, Department of Engineering,
University of Cambridge, United Kingdom
Guy Maisonnier, IFP Energie nouvelles, RueilMalmaison, France
Professor Lucjan Pawłowski, Division Four of
Engineering Sciences, Polish Academy of Sciences,
Warsaw, Poland
Professor Peter Reichetseder, Institute of Petroleum
Engineering, Clausthal University of Technology, Germany
Professor Rudy Swennen, Division of Geology, Catholic
University of Leuven, Belgium
Professor Mike Norton, EASAC Environment
Programme Secretary
EASAC – the European Academies’ Science Advisory Council – is formed by the national science academies
of the EU Member States to enable them to collaborate with each other in providing advice to European
policy-makers. It thus provides a means for the collective voice of European science to be heard. EASAC was
founded in 2001 at the Royal Swedish Academy of Sciences.
Its mission reflects the view of academies that science is central to many aspects of modern life and that an
appreciation of the scientific dimension is a pre-requisite to wise policy-making. This view already underpins
the work of many academies at national level. With the growing importance of the European Union as an
arena for policy, academies recognise that the scope of their advisory functions needs to extend beyond the
national to cover also the European level. Here it is often the case that a trans-European grouping can be
more effective than a body from a single country. The academies of Europe have therefore formed EASAC so
that they can speak with a common voice with the goal of building science into policy at EU level.
Through EASAC, the academies work together to provide independent, expert, evidence-based advice about
the scientific aspects of public policy to those who make or influence policy within the European institutions.
Drawing on the memberships and networks of the academies, EASAC accesses the best of European science
in carrying out its work. Its views are vigorously independent of commercial or political bias, and it is open
and transparent in its processes. EASAC aims to deliver advice that is comprehensible, relevant and timely.
EASAC covers all scientific and technical disciplines, and its experts are drawn from all the countries of the
European Union. It is funded by the member academies and by contracts with interested bodies. The expert
members of EASAC’s working groups give their time free of charge. EASAC has no commercial or business
EASAC’s activities include substantive studies of the scientific aspects of policy issues, reviews and advice
about specific policy documents, workshops aimed at identifying current scientific thinking about major
policy issues or at briefing policy-makers, and short, timely statements on topical subjects.
The EASAC Council has 29 individual members – highly experienced scientists nominated one each by
the national science academies of EU Member States, by the Academia Europaea and by ALLEA. The
national science academies of Norway and Switzerland are also represented. The Council is supported by a
professional Secretariat based at the Leopoldina, the German National Academy of Sciences, in Halle (Saale)
and by a Brussels Office at the Royal Academies for Science and the Arts of Belgium. The Council agrees
the initiation of projects, appoints members of working groups, reviews drafts and approves reports for
For more information about EASAC and for copies of all our previous publications, please visit our website
EASAC, the European Academies’ Science Advisory Council, consists of representatives of the following
European national academies and academic bodies who have issued this statement:
Academia Europaea
All European Academies (ALLEA)
The Austrian Academy of Sciences
The Royal Academies for Science and the Arts of Belgium
The Bulgarian Academy of Sciences
The Croatian Academy of Sciences and Arts
The Academy of Sciences of the Czech Republic
The Royal Danish Academy of Sciences and Letters
The Estonian Academy of Sciences
The Council of Finnish Academies
The Académie des sciences
The German National Academy of Sciences Leopoldina
The Academy of Athens
The Hungarian Academy of Sciences
The Royal Irish Academy
The Accademia Nazionale dei Lincei
The Latvian Academy of Sciences
The Lithuanian Academy of Sciences
The Royal Netherlands Academy of Arts and Sciences
The Polish Academy of Sciences
The Academy of Sciences of Lisbon
The Romanian Academy
The Slovakian Academy of Sciences
The Slovenian Academy of Arts and Science
The Spanish Royal Academy of Sciences
The Royal Swedish Academy of Sciences
The Royal Society
The Norwegian Academy of Science and Letters
The Swiss Academies of Arts and Sciences
The affiliated network for Europe of
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German National Academy of Sciences
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