UK Shale gas: How much gas?
How safe to extract?
Prof Mike Stephenson
British Geological Survey
© NERC All rights reserved
Two main questions
•
How much gas is there?
o Is it worth investing?
o Is it worth thinking about risks and regulation if gas
extraction never happens?
•
How safe is it to extract?
o What are the main risks?
o What science can be done to understand risks
© NERC All rights reserved
How much gas is there?
Reserve and resource
•
•
•
Resource figure -amount of gas in the ground
(some of which might never be accessible)
Reserve figure -more sophisticated measure amount of gas that you might be able extract given
economics and other factors.
Recovery factor - proportion of the total gas
resource that can be extracted and is often
expressed as a percentage
© NERC All rights reserved
How much gas is there? Variation in
estimates and recovery factors
•
•
•
•
•
•
BGS approximate reserve estimates for DECC in 2010 5.3 tcf (150 BCM)
Advanced Resources (2011) which listed 97 tcf GIP and
20 tcf recoverable resources for the UK
Cuadrilla’s Lancashire licence their 1200 square
kilometres licence area 200 tcf GIP
IGas acreage first estimate GIIP 800mmboe, then
changed to c.1,600mmboe (millions barrels of oil
equivalent - 9.23 tcf)
Eden Energy 7 licences in South Wales GIIP) – 34.198 tcf
; Recoverable Volume – 12.799 tcf of gas’.
Dart Energy Original Gas in Place (OGIP) of 65.56 tcf
© NERC All rights reserved
How safe to extract?
© NERC All rights reserved
Main hazards/concerns
•
•
•
•
•
•
•
•
Earthquakes
Integrity of well casing and groundwater contamination
Radioactivity
Transportation of equipment, materials and wastes to
and from the site;
Emissions to air
Noise
Large volumes of water for fracking
Surface spillages of chemicals and waste waters
© NERC All rights reserved
•
•
•
Largest on 1 April
magnitude 2.3
felt >50 people
© NERC All rights reserved
Comparison of signals
•
•
Comparison of
signals from
the 1 April and
27 May
Waveforms
very similar, so
similar origin
BGS concluded that the earthquakes were a direct
consequence of the fluid injection during fracking
© NERC All rights reserved
Management of future tremors
•
•
Cuadrilla commissioned reports on the
tremors
DECC commissioned an expert group to
look at the reports and make
recommendations
•
•
•
•
© NERC All rights reserved
Small pre-injection and monitoring before
the main injection.
Growth direction should be monitored and
monitoring system for automatic locations
and magnitudes of any seismic events in
near real-time.
Operations should be stopped and
remedial action instituted, if events of
magnitude 0.5 ML or above are detected.
UK Govt yet to make a decision and
recommendations
Groundwater and rock stress
baseline studies
•
•
© NERC All rights reserved
How background
methane is there in
groundwater?
Which rocks are
stressed already so
should be avoided
for fracking
Commons Select Committee Call for evidence
on the ‘Impact of Shale Gas on Energy Markets’
•
•
•
•
•
•
•
•
What are the estimates for the amount of shale gas in place in the UK,
Europe, and the rest of the world, and what proportion is recoverable?
Why are the estimates for shale gas so changeable?
What are the prospects for offshore shale gas in the UK Continental
Shelf?
Should the UK consider setting up a wealth fund with the tax revenue
from shale gas?
What have been the effects of shale gas on the LNG industry?
Could shale gas lead to the emergence of a single, global gas market?
What are the effects on investment in lower-carbon energy
technologies?
What is the potential impact on climate change objectives of greater
use of shale gas?
© NERC All rights reserved
Conclusions
•
•
•
•
•
•
Resources and reserves estimates in Britain and
Europe vary widely
This is affecting investor confidence; also policy
makers aren't sure what to do….
Main British environmental concern has been
earthquakes. Studies recommend ‘traffic light’
system to manage tremors
BGS has initiated groundwater and rock stress
baseline studies
Commons Select Committee Call
14th Licensing Round
© NERC All rights reserved
Extra slides for discussion?
© NERC All rights reserved
What is shale gas?
Shale basics
•
•
•
•
Grey or black, soft
Fine grained
70% of the world’s surface
rocks are sedimentary; 50%
of those are shale.
Contain ~95 % of the
organic matter in
sedimentary rocks
1 mm
© NERC All rights reserved
What is shale gas?
Where does the organic material come from?
Land plant material
and seawater algae
collect in mud
Older, deeper shale
layer
© NERC All rights reserved
What is shale gas?
Burial over
millions of
years
•
Shale buried
•
Biological decay –
biogenic methane
•
Organic matter
‘cooked’ –
thermogenic methane
500 m
0m
© NERC All rights reserved
Old deep
shale layer
Conventional and unconventional
Conventional and unconventional
© NERC All rights reserved
Conventional and unconventional
sandstone
Sand grain
gas
gas
Sand grain
0.25mm
© NERC All rights reserved
shale
Conventional and unconventional
Adsorbed gas and gas in pores
•
•
•
•
Phytoclast
Pyrite
© NERC All rights reserved
Pore space gas
Adsorbed gas
calculation of gas
in place per unit
volume
We have to
measure how
much shale
Conventional and unconventional
Conventional: Trap
© NERC All rights reserved
Unconventional:
Continuous
accumulation
Conventional and unconventional
Fracking basics
•
•
Cracks the shale
High pressure water or nitrogen,
350-700 bar (350 to 700
atmospheres)
© NERC All rights reserved
Contamination from fracking?
Osborn et al. 2011, PNAS
•
Studied:
•
•
Methane in
shallow
water wells
in shale gas
areas
measured
methane
content and
δ13C
© NERC All rights reserved
Molofsky et al. 2011
Not peer
reviewed
Dec 2011
© NERC All rights reserved
© NERC All rights reserved
Molofsky et al. 2011
Blackpool seismicity
The Blackpool region
- low seismicity even
for the UK.
2.5 in 1970 5 km
south-west of
Blackpool.
number of smaller
earthquake
immediately offshore.
The magnitude 3.7
Ulverston earthquake
28 April 2009
© NERC All rights reserved
How much gas is there? Complex terminology
Terms for resources
and reserves
Term
Acronym
Summary
Resource
‘How much gas is in
the ground’
Original gas in place
OGIP
Total volume of gas
Gas (initially) in place
GIIP/GIP
Total volume of gas
Reserve
‘How much gas could
be extracted’
Ultimately recoverable
Total recoverable
volume
Technically recoverable
Limited by
technology
Limited by economics
Economically
recoverable
Reserves
Proved reserves
Total producible gas
1P
Median figure of
2P
reserves
High figure of reserves 3P
© NERC All rights reserved
Probability of
reserves (proven)
Proven and probable
Proved, probable and
possible
Damage very unlikely to have
been caused by
earthquake
© NERC All rights reserved