methodological developments to define safety criteria
TRANSCRIPT
Friday, 17 August 2007
Methodological developments to define safety criteria
Olivier BOUC
3rd IEA GHG Risk Assessment Network Meeting - London
Friday, 17 August 2007
3rd Risk Assessment Network Meeting - London
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Frame of our research
> BRGM research about safety criteria for CO2 geological storage� Internal research project
� 3 years project funded by the National ResarchAgency, with TOTAL, Armines, University Paul Sabatier (Toulouse), University of Neuchâtel
“Safety criteria for CO2 geological storage: qualitative/quantitative approach of risk scenarios”
> Aim: contribute to demonstrating safety of CO2 geological storage
> Safety criteria � performance objectives
Friday, 17 August 2007
3rd Risk Assessment Network Meeting - London
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Safety criteria
> Requirements to ensure near-zero local impacts on health, safety and the environment in the short, middle and long term� Qualitative / generic
� Quantitative / site specific
Friday, 17 August 2007
3rd Risk Assessment Network Meeting - London
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Purpose
> Provide a simple workflow to evaluate safety in a licensing process� Build long-term evolution scenarios
� Evaluate potential targets exposure using simple models
� Determine safety criteria
> Not a risk assessment� Rather keys to control a risk assessment
> First choose a method to build scenarios� Methodological exercise to try the use of FEPs
Friday, 17 August 2007
3rd Risk Assessment Network Meeting - London
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Context of the assessment
> Hypothetical storage site
> In the East of the Paris Basin� Strategic aquifer at -800m
> In the Dogger aquifer� -1700m, thickness 25m
� Nearly flat reservoir, very slow natural flow (1m/yr)
� Near hydrostatic stress state
� � ~ 16% ; K ~ 1 D ; T ~ 55-75°C ; P ~ 173 bars
4- GroupingWhich EPs do present similarities?
1- IdentificationWhich FEPs do enter the frame of analysis?
EPsCharacterised Fs
2- EvaluationProbability / Potential impacts
EPs and associated risk level
Excluded FEPs
Interaction matrix / influence diagram
between EPs groups
6- InteractionsWhich interaction intensity between EPs Groups?
7- Alternate scenarios constitution
Alternate scenarios composed by EPs
groups and related Fs
5- F-EPs CorrelationWhich Fs linked to which EPs groups?
Fs linked to EPs groups
3- SelectionDepending on the risk level determined
Alternate scenarios EPs
Screened out EPs
Reference scenario EPs
Reference scenario
EPs Groups
FEPs database workflow used
• Quintessa
online FEPs
database
• Workflow
closely inspired
by Vattenfall &
TNO « Safety
assessment of
structure
Schweinrich »
in CO2STORE
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3rd Risk Assessment Network Meeting - London
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Results: six leakage scenarios identified
1
2 33
45
6
1 Well degradation
2 Cap rock fracturing due to overpressure
3 Leakage through buoyancy
4 Leakage through a fault
5 Reservoir water migration
6 Open hole leakage
Saline water migration
Aquifer regional flow
CO2 migration
Pressure front propagation
Overpressure
Fault
CO2 injection well
Hydrocarbons extraction well
Observation well
Reservoir
Freshwateraquifer
Friday, 17 August 2007
3rd Risk Assessment Network Meeting - London
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Feedback from our attempt
> Method not optimal� Tedious and time-consuming
� Result: very little surprise compared to the investment!
� Very close to the results of the CO2STORE study
> Some steps arguable� OK for steps 1-3 (Identification – Evaluation –
Selection)
� Step 4 (Grouping) determining and questionable: seems very subjective
� Idem for step 7 (Deducing scenarios from influence diagram)
> Results achieved by giving up steps 4-7
Friday, 17 August 2007
3rd Risk Assessment Network Meeting - London
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Restrictions
> Only a test – first use of the tool
> Hypothetical site ���� lack of real data
> Not an expert panel
> Difference TNO – Quintessa database� TNO maybe more suitable for this method
� But would it really be more time-efficient ?
> Schweinrich case study hypotheses close to ours
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3rd Risk Assessment Network Meeting - London
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Feedback (2)
> Main advantages of the FEPs� Comprehensiveness
� Systematic documentation of the evaluation
> Is this really appropriate in our approach?
> Maybe not a scenario-building tool?
> Rather an audit tool� “Top-down” use
� Cf. Quintessa document (Savage et al.[2004], A generic FEP database for the assessment of long-term performance and safety of the geological storage of CO2)
Friday, 17 August 2007
3rd Risk Assessment Network Meeting - London
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Possible scenario construction methods
> Non-FEPs approaches:� GEODISC (Australia): an expert panel reviews a
limited number of risk events (probability/impacts)
> FEPs approaches� Battelle, Mountaineer (USA): more qualitative and
quick screening of the FEPs DB. Decision oriented for risk management.
> Mixed approach:� Identification of simple scenarios by an expert panel
� Audit with the generic FEPs database
Friday, 17 August 2007
3rd Risk Assessment Network Meeting - London
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Further work and perspectives
> Base safety criteria on potential targets> Develop a site model representing the
potentially exposed elements> Link risk scenarios to targets exposure> Build simple models to evaluate CO2
fluxes between compartments� Analytical, semi-analytical, 1D
� How to ensure they are representative?
� Address uncertainties
> Infer safety criteria
10 km
CO2 injection well
Oil extraction well
Facility where CO2 is produced and captured
River
City: economic activity and living area
Site with nature conservation measures
Site with heritage protection measures
Observation well
Zone widely devoted to agricultural land use
Site model
for CO2 storage in aquifer underneath the
Paris Basin
Aquifer regional flow direction
Fault
NB : local topography is overstated in comparison to the scale for subsurface depth
Potential CO2 leakages (6 identified scenarios)
31
?
2 5 6
CO2 injection
4
Potentially exposed elements
Reservoir
Aquifer to be preserved
Potable water catchment