© NERC All rights reserved UK Shale gas: How much gas? How safe to extract? Prof Mike Stephenson British Geological Survey.

© NERC All rights reserved

UK Shale gas: How much gas? How safe to extract?

Prof Mike Stephenson

British Geological Survey


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


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


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


How safe to extract?


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


• Largest on 1 April

• magnitude 2.3

• felt >50 people


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


Management of future tremors

• Cuadrilla commissioned reports on the tremors

• DECC commissioned an expert group to look at the reports and make recommendations• 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

• 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?


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


Extra slides for discussion?


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

What is shale gas?


Where does the organic material come from?

Land plant material and seawater algae collect in mud

Older, deeper shale layer

What is shale gas?


500 m

0 m

What is shale gas?

• Shale buried

• Biological decay – biogenic methane

• Organic matter ‘cooked’ – thermogenic methane

Old deep shale layer

Burial over millions of years


Conventional and unconventional



Sand grain

Sand graingas

gas

0.25mm

shalesandstone



Adsorbed gas and gas in pores

• Pore space gas

• Adsorbed gas

• calculation of gas in place per unit volume

• We have to measure how much shale

Phytoclast

Pyrite



Shale layer

sandstone

Cap rockConventional: Trap

Unconventional:Continuous

accumulation



Fracking basics

• Cracks the shale

• High pressure water or nitrogen, 350-700 bar (350 to 700 atmospheres)



Contamination from fracking?Osborn et al. 2011, PNAS

• Studied:• Methane in

shallow water wells in shale gas areas

• measured methane content and

δ13C


Not peer reviewedDec 2011

Molofsky et al. 2011

© NERC All rights reserved Molofsky et al. 2011


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

Blackpool seismicity


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

Ultimately recoverable Total recoverable volume

Technically recoverable

Limited by technology

Economically recoverable

Limited by economics

Reserve‘How much gas could be extracted’

Reserves Total producible gas

Proved reserves 1P Probability of reserves (proven)

Median figure of reserves

2P Proven and probable

High figure of reserves 3P Proved, probable and possible


Damage very unlikely to have been caused by earthquake

© NERC All rights reserved UK Shale gas: How much gas? How safe to extract? Prof Mike Stephenson British Geological Survey.

Documents

tcf of gas

rights reserved uk shale

impact of shale gas

effects of shale gas

offshore shale gas

shale gas lead

gas extraction

rights reserved groundwater