Professor Mike Stephenson, Head of Science (Energy) at the British Geological Survey (BGS) leads a Global CCS Institute webinar on the long-term fate of CO2 in the subsurface environment.
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British Geological Survey/NCCCS – The long-term fate of CO2 in the subsurface environment
1. GLOBAL CCS INSTITUTE
The long-term fate of CO2 in the subsurface environment
Mike Stephenson and Jonathan Pearce
British Geological Survey/Nottingham Centre for CCS
WWW.GLOBALCCSINSTITUTE.COM
2. GLOBAL CCS INSTITUTE
MIKE STEPHENSON
Head of Science (Energy) at the British
Geological Survey (BGS)
- Professor Stephenson runs the Energy
Programme at BGS including carbon
capture and storage, hydrocarbons,
renewables and unconventional energy
- Director of the Nottingham Centre for
Carbon Capture and Storage, a joint venture
between the BGS and the University of
Nottingham.
- Mike earned a BSc, MSc and PhD from
the University of Sheffield and Imperial
College, London as well as various
postgraduate teaching qualifications.
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JONATHAN PEARCE
Job Title at Organisation
-Jonathan Pearce, over 24 years experience
with BGS.
-Involved in CO2 storage research since the
early 1990s and has led a number of
research projects on long-term geochemical
processes and the development of shallow
monitoring tools in CO2 Storage.
-His research has allowed him to collaborate
with other researchers globally including in
China, Australia, Canada, South Africa and
widely across Europe.
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4. GLOBAL CCS INSTITUTE
THE LONG TERM
FATE OF CO2 IN
THE
SUBSURFACE
ENVIRONMENT
Mike Stephenson
Jonathan Pearce
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Regulation and public confidence
VERY IMPORTANT
Building the three-dimensional static geological earth model
Using the data collected in Step 1, a three-dimensional static geological earth model, or a set of such models, of
the candidate storage complex, including the caprock and the hydraulically connected areas and fluids shall
be built using computer reservoir simulators. The static geological earth model(s) shall characterise the
complex in terms of:
(a) geological structure of the physical trap;
(b) geomechanical, geochemical and flow properties of the reservoir overburden (caprock, seals, porous and
permeable horizons) and surrounding formations;
(c) fracture system characterisation and presence of any human-made pathways;
(d) areal and vertical extent of the storage complex;
(e) pore space volume (including porosity distribution);
(f) baseline fluid distribution;
(g) any other relevant characteristics.
J
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Storage and time
„Free CO2‟ Physical trap
Time =?
TIME Dissolved CO2 Solubility trap
Time =?
Carbonate minerals Mineral trap
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The first 1780 years: free CO2
free CO2
CO2 injection starts
Storage and time M
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Solubility trapping : Sleipner, the next 275 years
free CO2 CO2 in solution
2070 (20 Mt) Second ceases of reservoir. First repeat survey
2270 (2.3
1999 CO2 reaches top
2001 (4.3Mt) Injectionrepeat survey
2020
Storage and time: effects of impurities on solubility? [courtesy Erik Lindeberg, SINTEF] J
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Lab dissolution experiment
Free CO2
Saline water
195ss
90
150
255sss
0135
s
105
120
60
[BGS Hydrothermal Laboratory] Storage and time J
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HOW COULD WE DEFINE „LONG TERM‟?
When...?
Complete dissolution
Stabilisation
• Approaches to defining appropriate time scales of post-closure:
– When complete dissolution of CO2 occurs?
– When stability of CO2 migration is reached? (creation of CO2 reservoir)
– When a “new” THMC equilibrium is reached? (steady- state regime)
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CONFORMITY WITH MODELS
• Any assessment of permanency will rely on models
– Hence the validity of static and dynamic models is critical
• Validity and robustness is tested by comparing model predictions with
past monitoring data (so-called history-matching)
• Suggested tests:
– A model matches historical flow/pressure data to within x% of the
actual measured data.
– If a static model has not been revised over e.g. 5 years, and still
adequately enables predictions to match monitored performance,
then the static model may be considered robust and representative.
• Key issues are:
– What is adequate? (e.g. within 5% or 10%?)
– The acceptable range deemed to meet measurements will vary with
parameter and is likely to be specified as a condition of the storage
permit
– What if there is more than one unique solution?
– Updates to models should be expected as more data is obtained J
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CONFORMITY WITH MODELS
• Models used to predict future performance
should be those that have been used during site
characterisation and development of monitoring
plan (subject to approved revisions)
• The regulator might want to review the changes
undertaken to models during the project
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DEMONSTRATING LONG-TERM
STABILITY
• Model scenarios should be conservative –
parameters should be far from expected values
(e.g. 2δ)
• Define acceptable % deviation from stable value
(5-10%)
• Models predict eventual stability of the plume
with no evidence of potential future leakage
• Key monitored parameters should be within a
predetermined range to the future stable values
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CONCLUSIONS
• Key trapping mechanisms are:
– Physical containment
– Residual trapping
– CO2 dissolution
– Mineral trapping
• Demonstrating long-term performance is
fundamental to transferring long-term liability to the
State.
• Storage risk goes down with time
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ACKNOWLEDGEMENTS
Sam Holloway (BGS)
Andy Chadwick (BGS)
Mercedes Maroto-Valer (NCCCS)
Sarah Mackintosh (NCCCS)
Antony Benham (NCCCS)
Sarah Hannis (BGS)
John Williams (BGS)
Andy Newell (BGS)
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QUESTIONS
You can submit questions
to us simply by typing
your question directly into
the GoToWebinar control
Panel.
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