- Email: [email protected]
Oltenia CCS Demo Project- Preliminary Technical Risk Assessment
Available online at www.sciencedirect.com
ScienceDirect Energy Procedia 63 (2014) 4677 – 4683
GHGT-12
Oltenia CCS Demo Project- Preliminary technical risk assessment Sorin Anghel1 1
National Institute of Marine Geology and Geoecology Str. Dimitrie Onciul, Nr. 23-25, RO-024053, Bucharest, Romania, [email protected]
Abstract
Hazards have been referenced by the functional element to which they are associated: Reservoir, Caprock, Faults, CO2, Overburden, Underburden, and Wells.They have been classified according to the detectable undesired event that they could potentially lead to, in the context of CO2 injection in the subsurface. When a hazard can lead to several events, it has been repeated in the relevant sections of the table. A high level review of the potential consequences of each undesired event is provided in the column “Consequences”. It is understood that the consequences of the same event could be different, depending on the hazard which is causing this event. Nonetheless, as this is a preliminary exercise this fact has not been formally represented in the table.Finally, a high level screening of the potential prevention measures that could be put in place at different phases of the project (appraisal, construction, injection/monitoring) as well as mitigation measures are provided in the last column of the table.This list is not meant to be exhaustive but its objective is rather to highlight the most important technical risks associated to the project and plan accordingly for the next phases (in particular the appraisal). As mentioned before, due to the early stage of the project, a quantitative assessment of the risks has not been performed as part of this task. However, a preliminary analysis of the criticity of the risks associated with the identified hazards was conducted with the objective to highlight what were felt as the major concerns concerning the two candidate sites at this stage of the project.Again, the data currently available not allowing us to discriminate meaningfully between the two zones, this has been kept as a common exercise. At this early stage of the project, only a preliminary risk assessment is possible, with the following consequences: no risk scenario has been explicitly described, but only individual hazards (which will form the “building pieces” of risk scenarios); no quantitative evaluation of severity and likelihood has been made; each of the two candidate zones has specific risk factors. However, given the current level of understanding, it has been decided that a meaningful discrimination between the two zones was not yet possible and therefore, the exercise has been kept as common for both zone 1 and zone 5. Hazards and undesired events must be defined as deviations from a “base case” scenario. The characteristics of this base case are:the injected CO2 stays within the planned reservoir formations ; CO2 never reaches the bounding faults, which are nevertheless assumed as sealing;no unplanned shut down of injectors during the injection phase. all existing wells are sealing; injection rates and quantities as per plan and used in the Eclipse simulations. It
1876-6102 © 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/). Peer-review under responsibility of the Organizing Committee of GHGT-12 doi:10.1016/j.egypro.2014.11.501
4678
Sorin Anghel / Energy Procedia 63 (2014) 4677 – 4683
is important to stress that risk analysis is a continuous and iterative process, and that more accurate information from appraisal, verification and monitoring can improve the knowledge of a storage site, and can therefore adjust the severity and likelihood defined for each risk, and can finally lead to an updated mitigation and prevention plan (including monitoring). The workflow for a complete risk analysis and monitoring plan is as follows :define severity (i.e. impact) levels for each stake (health, financial, safety, and environment), according to the risk matrix of the organization; define likelihood (i.e. probability) levels; identify all project risks associated with performance reduction. The key performance indicators are injectivity, capacity and containment Evaluate their likelihood and severity; place them in the Risk Matrix to identify scenario (hazard – event – consequence) with the highest criticity; prepare mitigation plans to reduce likelihood and prevention plans to reduce severity to such levels that all the residual risks are within the acceptable levels for the organization (including local/ international regulations etc.) © Published by Elsevier Ltd. This © 2014 2013The TheAuthors. Authors. Published by Elsevier Ltd. is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/). Selection and peer-review under responsibility of GHGT. Peer-review under responsibility of the Organizing Committee of GHGT-12 Keywords: prevention plan, residual risk, workflow, risk scenarios, monitoring
1.Objective and assumptions 1.1 Objectives The objectives of this task are: x x x
To identify the major technical hazards associated with the Romanian CCS demo project using zone 1 or 5 (as defined in GeoEcoMar’s “Sites selection report”) as a storage site. To identify the possible consequences of undesired events resulting from the combination of these hazards with the injection of CO2 in the subsurface. To propose prevention and mitigation measures to be put in place in order to decrease the criticity of the risks associated with these undesired events.
1.2 Assumptions The present report covers the identification of the technical hazards associated with the two potential candidate sites. Other types of hazards, related to legislation, permitting, conflict of interest, financing, public acceptance, communication and project management have not been reviewed in this study and are assumed to be covered by GeoEcoMar . Prevention measures, including the use of monitoring technologies are proposed in this report, but the analysis of the applicability of these technologies to the two candidate sites has been kept separate. . At this early stage of the project, only a preliminary risk assessment is possible, with the following consequences: x x x
No risk scenario has been explicitly described, but only individual hazards (which will form the “building pieces” of risk scenarios); No quantitative evaluation of severity and likelihood has been made; Each of the two candidate zones has specific risk factors. However, given the current level of understanding, it has been decided that a meaningful discrimination between the two zones was not yet possible and therefore, the exercise has been kept as common for both zone 1 and zone 5.
Sorin Anghel / Energy Procedia 63 (2014) 4677 – 4683
4679
Hazards and undesired events must be defined as deviations from a “base case” scenario. The characteristics of this base case are listed below: x x x x x
The injected CO2 stays within the planned reservoir formations (Sa5 and Sa7 for zone 1 and Sa3, Sa4, Sa5a and Sa5 for zone 5) CO2 never reaches the bounding faults, which are nevertheless assumed as sealing No unplanned shut down of injectors during the injection phase. All existing wells are sealing Injection rates and quantities as per plan and used in the Eclipse simulations.
2. Definitions and methodology 2.1 Definitions Hazard: any object, product, physical condition or effect that has the potential to cause an undesired event. In this document we focus on technical hazards. Undesired event: event caused by the combination of a hazard and an activity (in our case, the injection of CO2 in the subsurface) having a negative impact on the site performance factors and subsequently on the project stakes (health, financial, safety, reputation, environment…). Risk: defined as a measure of the likelihood of occurrence of an undesired event and the potential severity of the consequences. Risk criticity: is defined as the position of a given risk along an axis with a range from “negligible” to “non acceptable”. This “graduations” of this axis need to be specifically defined for the project, in relation with the likelihood and severity matrixes. Prevention measure: measure aiming at reducing the likelihood of an undesired event (through a specific hazard). Mitigation measure: measure aiming at reducing the severity of a consequence. Element: for the purpose of this exercise, the subsurface at the storage sites has been divided into simple functional elements for an easier classification of hazards. They are: reservoir, caprock, faults, wells, overburden, underburden.Storage complex: according to the EU definition, it is “the storage site and the surrounding geological domain which can have an effect on overall storage integrity and security; that is, secondary containment formations”. At this stage of the project, no secondary seal has been identified yet and we will therefore consider the reservoir formations (as listed in 1.3) in combination with the expected primary caprocks (Sarmatian above Sa7 for zone 1 and Sarmatian above Sa5 for zone 5) as storage complex for each of the two zones (the lateral boundaries of the complex will need further work to be defined). This definition can be easily modified if/when a secondary caprock is identified and doesn’t impact the relevance of the present exercise. Storage site: according to the EU definition, it is “a defined volume area within a geological formation used for the geological storage of CO2 and associated surface and injection facilities.” Leakage: according to the EU definition, it consists in “any release of CO2 from the storage complex” 2.2 Methodology The workflow for a complete risk analysis and monitoring plan is as follows (Error! Reference source not found.): 1. 2. 3. 4.
Define severity (i.e. impact) levels for each stake (health, financial, safety, and environment), according to the risk matrix of the organization. Define likelihood (i.e. probability) levels. Identify all project risks associated with performance reduction. The key performance indicators are injectivity, capacity and containment (any loss of performance may impact the stakes listed in 1.). Evaluate their likelihood and severity.
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Sorin Anghel / Energy Procedia 63 (2014) 4677 – 4683
5. 6.
7.
Place them in the Risk Matrix to identify scenario (hazard – event – consequence) with the highest criticity. Prepare mitigation plans to reduce likelihood and prevention plans to reduce severity to such levels that all the residual risks are within the acceptable levels for the organization (including local/ international regulations etc.) Review periodically as new information arrives
Fig. 1. General methodology for risk analysis
Likelihood POTENTIAL RISK
Ligh
1 Serious 2 Major 3 Catastrophic 4 Multi Catastrophic 5
↑
Very Low Medium low 1 2 3
O Severity→
Severity
MITIGATION Control measures PREVENTION ←
-1
LIKELIHOOD -2 -3
-2
-4
-3 -4 -5
High 4
Very High 5
→ -4
-5
-6
-8
-10
-6
-9
-12
-15
-8
-12
-16
-20
-20
-25
-10
-15
Potential risk matrix Fig.2 Potential risk matrix
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Sorin Anghel / Energy Procedia 63 (2014) 4677 – 4683
Likelihood RESIDUAL RISK EXTREME HIGH
-25 to -20 -19 to -10
Serious Major Catastrophic Multi Catastrophic
MEDIUM LOW Proceed carefuly INSIGNIFICANT Safe to proceed Very Low Medium High Very low High 1 2 3 4 5
O
← Ligh
↑
1 2 3 4 5
Severity→
Severity
-9 to -5 -4 to -2 -1 MITIGATION Control measures PREVENTION
Do not take this risk
-1
-2
-2
-4
-3 -4 -5
LIKELIHOOD -3
→ -4
-5
-6
-8
-10
-6
-9
-12
-15
-8
-12
-16
-20
-10
-15
-20
-25
Residual risk matrix Fig.3 Residual risk matrix
It is important to stress that risk analysis is a continuous and iterative process, and that more accurate information from appraisal, verification and monitoring can improve the knowledge of a storage site, and can therefore adjust the severity and likelihood defined for each risk, and can finally lead to an updated mitigation and prevention plan (including monitoring).Considering the availability of data and information available at this stage, and as stated above, only a preliminary risk assessment has been performed as part of this task, partly addressing steps 3 and 6 of the methodology described above and following the steps listed below: x Division of the subsurface at the storage sites into functional elements. x
Identification of the main hazards for each element.
x
For each of these hazards, identify the associated detectable (through monitoring) undesired event(s) that could result of their combination with injection of CO2 in the subsurface.
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Sorin Anghel / Energy Procedia 63 (2014) 4677 – 4683
x
Identify the potential direct and indirect consequences of these undesired events.
x
Identify prevention and mitigation measures that could be put in place to reduce the likelyhood and severity of the risks identified.
This exercise has been performed by conducting a workshop with the contribution of all subsurface team members involved in the project. 3. Study results 3.1 Hazards identification table Hazards have been referenced by the functional element to which they are associated: Reservoir, Caprock, Faults, CO2, Overburden, Underburden, and Wells. They have been classified according to the detectable undesired event that they could potentially lead to, in the context of CO2 injection in the subsurface. When a hazard can lead to several events, it has been repeated in the relevant sections of the table. A high level review of the potential consequences of each undesired event is provided in the column “Consequences”. It is understood that the consequences of the same event could be different, depending on the hazard which is causing this event. Nonetheless, as this is a preliminary exercise this fact has not been formally represented in the table. Finally, a high level screening of the potential prevention measures that could be put in place at different phases of the project (appraisal, construction, injection/monitoring) as well as mitigation measures are provided in the last column of the table. This clasification is not meant to be exhaustive but its objective is rather to highlight the most important technical risks associated to the project and plan accordingly for the next phases (in particular the appraisal). 3.2 Preliminary criticity analysis As mentioned before, due to the early stage of the project, a quantitative assessment of the risks has not been performed as part of this task. However, a preliminary analysis of the criticity of the risks associated with the identified hazards was conducted with the objective to highlight what were felt as the major concerns concerning the two candidate sites at this stage of the project. Again, the data currently available not allowing us to discriminate meaningfully between the two zones, this has been kept as a common exercise. The most critical hazards identified are presented in Table 1 below:
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Sorin Anghel / Energy Procedia 63 (2014) 4677 – 4683
Element
Hazard
Main Performance Factor impacted Containment
Reservoir
Insufficient lateral extent of pinch outs
Caprock
Unidentified conductive faults crossing caprock
Containment
Caprock
Unidentified fracture corridors crossing caprock
Containment
Caprock
Permeability underestimated
Containment
Wells
Existing P&A wells leaking
Containment
Faults
Unidentified faults within the reservoir not laterally transmissive
Faults
Bounding fault not sealing vertically* or laterally
Reservoir
Permeability lower than expected
Injectivity
Reservoir
Porosity lower than expected
Capacity
Reservoir
Plugging due to salting out around well
Injectivity
Capacity, Injectivity Containment
Table 1: Hazards with high perceived criticity * This looks to be more of an issue for zone 5 where the bounding faults are seen on existing 2D lines to extend higher than the top of caprock It can be seen that most of these hazards are associated to concerns about the containment of the future storage site. It can also be noted that the presence of most of these hazards in this list is due to the current lack of data available to the project and that thorough appraisal campaigns should be able to remove most of the uncertainty associated to these concerns. References [1] Anthonsen, K.L., P. Aagaard, P. E. S. Bergmo, M. Erlström, J.I. Fareide, S. R. Gislason, G. M. Mortensen, S. Ó. Snæbjörnsdottir, 2013. CO2 storage potential in the Nordic region. Energy Procedia 37, 5080 –5092. [2] Szizybalski, S., Kollersberger, T., Möller, F., Martens, S., Liebscher, A., Kühn, M. (2014): Communication Supporting the Research on CO2 Storage at the Ketzin Pilot Site, Germany - A Status Report after Ten Years of Public Outreach. Energy Procedia, 51, 2014, 274-280 [3] Eiken, O., Ringrose, P., Hermanrud, C., Nazarian, B., Torp T.A.,, Lars Høier L. Lessons learned from 14 years of CCS operations: Sleipner, In Salah and Snøhvit, Energy Procedia 4, 2011, 5541–5548. [4] Juhlin C., Ask M., Bjelm L., Elhami E., Erlström M., Joodaki S., Lazor P., Lorenz H., Niemi A., Rosberg J.E. and Sopher D.Potential for CO2 storage in Swedish bedrock: SwedSTORECO2 - Phase 1. Final Report, 125 pp. [5] Rütters, H. and the CGS Europe partners. State of play on CO2 geological storage in 28 European countries. CGS Europe report No. D2.10, June 2013. 1-89. [6] One North Sea: A study into North Sea cross-border CO2 transport and storage. 2010, http://www.npd.no/no/Publikasjoner/Rapporter/Samarbeider-om-CO2-lager/ [7] Haselton T. M. Exploiting the ROZ in Lithuania. Presented at the 19th Annual CO2 Flooding Conference, Midland, Texas, 14.12. 2013. http://www.co2conference.net/wp-content/uploads/2013/12/15-Haselton-Exploiting-the-ROZ-in-Lithuania-new-new.pdf [8] Poirot J. M. Technical risk assessment –CCS Storage project report-Schumberger
ScienceDirect Energy Procedia 63 (2014) 4677 – 4683
GHGT-12
Oltenia CCS Demo Project- Preliminary technical risk assessment Sorin Anghel1 1
National Institute of Marine Geology and Geoecology Str. Dimitrie Onciul, Nr. 23-25, RO-024053, Bucharest, Romania, [email protected]
Abstract
Hazards have been referenced by the functional element to which they are associated: Reservoir, Caprock, Faults, CO2, Overburden, Underburden, and Wells.They have been classified according to the detectable undesired event that they could potentially lead to, in the context of CO2 injection in the subsurface. When a hazard can lead to several events, it has been repeated in the relevant sections of the table. A high level review of the potential consequences of each undesired event is provided in the column “Consequences”. It is understood that the consequences of the same event could be different, depending on the hazard which is causing this event. Nonetheless, as this is a preliminary exercise this fact has not been formally represented in the table.Finally, a high level screening of the potential prevention measures that could be put in place at different phases of the project (appraisal, construction, injection/monitoring) as well as mitigation measures are provided in the last column of the table.This list is not meant to be exhaustive but its objective is rather to highlight the most important technical risks associated to the project and plan accordingly for the next phases (in particular the appraisal). As mentioned before, due to the early stage of the project, a quantitative assessment of the risks has not been performed as part of this task. However, a preliminary analysis of the criticity of the risks associated with the identified hazards was conducted with the objective to highlight what were felt as the major concerns concerning the two candidate sites at this stage of the project.Again, the data currently available not allowing us to discriminate meaningfully between the two zones, this has been kept as a common exercise. At this early stage of the project, only a preliminary risk assessment is possible, with the following consequences: no risk scenario has been explicitly described, but only individual hazards (which will form the “building pieces” of risk scenarios); no quantitative evaluation of severity and likelihood has been made; each of the two candidate zones has specific risk factors. However, given the current level of understanding, it has been decided that a meaningful discrimination between the two zones was not yet possible and therefore, the exercise has been kept as common for both zone 1 and zone 5. Hazards and undesired events must be defined as deviations from a “base case” scenario. The characteristics of this base case are:the injected CO2 stays within the planned reservoir formations ; CO2 never reaches the bounding faults, which are nevertheless assumed as sealing;no unplanned shut down of injectors during the injection phase. all existing wells are sealing; injection rates and quantities as per plan and used in the Eclipse simulations. It
1876-6102 © 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/). Peer-review under responsibility of the Organizing Committee of GHGT-12 doi:10.1016/j.egypro.2014.11.501
4678
Sorin Anghel / Energy Procedia 63 (2014) 4677 – 4683
is important to stress that risk analysis is a continuous and iterative process, and that more accurate information from appraisal, verification and monitoring can improve the knowledge of a storage site, and can therefore adjust the severity and likelihood defined for each risk, and can finally lead to an updated mitigation and prevention plan (including monitoring). The workflow for a complete risk analysis and monitoring plan is as follows :define severity (i.e. impact) levels for each stake (health, financial, safety, and environment), according to the risk matrix of the organization; define likelihood (i.e. probability) levels; identify all project risks associated with performance reduction. The key performance indicators are injectivity, capacity and containment Evaluate their likelihood and severity; place them in the Risk Matrix to identify scenario (hazard – event – consequence) with the highest criticity; prepare mitigation plans to reduce likelihood and prevention plans to reduce severity to such levels that all the residual risks are within the acceptable levels for the organization (including local/ international regulations etc.) © Published by Elsevier Ltd. This © 2014 2013The TheAuthors. Authors. Published by Elsevier Ltd. is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/). Selection and peer-review under responsibility of GHGT. Peer-review under responsibility of the Organizing Committee of GHGT-12 Keywords: prevention plan, residual risk, workflow, risk scenarios, monitoring
1.Objective and assumptions 1.1 Objectives The objectives of this task are: x x x
To identify the major technical hazards associated with the Romanian CCS demo project using zone 1 or 5 (as defined in GeoEcoMar’s “Sites selection report”) as a storage site. To identify the possible consequences of undesired events resulting from the combination of these hazards with the injection of CO2 in the subsurface. To propose prevention and mitigation measures to be put in place in order to decrease the criticity of the risks associated with these undesired events.
1.2 Assumptions The present report covers the identification of the technical hazards associated with the two potential candidate sites. Other types of hazards, related to legislation, permitting, conflict of interest, financing, public acceptance, communication and project management have not been reviewed in this study and are assumed to be covered by GeoEcoMar . Prevention measures, including the use of monitoring technologies are proposed in this report, but the analysis of the applicability of these technologies to the two candidate sites has been kept separate. . At this early stage of the project, only a preliminary risk assessment is possible, with the following consequences: x x x
No risk scenario has been explicitly described, but only individual hazards (which will form the “building pieces” of risk scenarios); No quantitative evaluation of severity and likelihood has been made; Each of the two candidate zones has specific risk factors. However, given the current level of understanding, it has been decided that a meaningful discrimination between the two zones was not yet possible and therefore, the exercise has been kept as common for both zone 1 and zone 5.
Sorin Anghel / Energy Procedia 63 (2014) 4677 – 4683
4679
Hazards and undesired events must be defined as deviations from a “base case” scenario. The characteristics of this base case are listed below: x x x x x
The injected CO2 stays within the planned reservoir formations (Sa5 and Sa7 for zone 1 and Sa3, Sa4, Sa5a and Sa5 for zone 5) CO2 never reaches the bounding faults, which are nevertheless assumed as sealing No unplanned shut down of injectors during the injection phase. All existing wells are sealing Injection rates and quantities as per plan and used in the Eclipse simulations.
2. Definitions and methodology 2.1 Definitions Hazard: any object, product, physical condition or effect that has the potential to cause an undesired event. In this document we focus on technical hazards. Undesired event: event caused by the combination of a hazard and an activity (in our case, the injection of CO2 in the subsurface) having a negative impact on the site performance factors and subsequently on the project stakes (health, financial, safety, reputation, environment…). Risk: defined as a measure of the likelihood of occurrence of an undesired event and the potential severity of the consequences. Risk criticity: is defined as the position of a given risk along an axis with a range from “negligible” to “non acceptable”. This “graduations” of this axis need to be specifically defined for the project, in relation with the likelihood and severity matrixes. Prevention measure: measure aiming at reducing the likelihood of an undesired event (through a specific hazard). Mitigation measure: measure aiming at reducing the severity of a consequence. Element: for the purpose of this exercise, the subsurface at the storage sites has been divided into simple functional elements for an easier classification of hazards. They are: reservoir, caprock, faults, wells, overburden, underburden.Storage complex: according to the EU definition, it is “the storage site and the surrounding geological domain which can have an effect on overall storage integrity and security; that is, secondary containment formations”. At this stage of the project, no secondary seal has been identified yet and we will therefore consider the reservoir formations (as listed in 1.3) in combination with the expected primary caprocks (Sarmatian above Sa7 for zone 1 and Sarmatian above Sa5 for zone 5) as storage complex for each of the two zones (the lateral boundaries of the complex will need further work to be defined). This definition can be easily modified if/when a secondary caprock is identified and doesn’t impact the relevance of the present exercise. Storage site: according to the EU definition, it is “a defined volume area within a geological formation used for the geological storage of CO2 and associated surface and injection facilities.” Leakage: according to the EU definition, it consists in “any release of CO2 from the storage complex” 2.2 Methodology The workflow for a complete risk analysis and monitoring plan is as follows (Error! Reference source not found.): 1. 2. 3. 4.
Define severity (i.e. impact) levels for each stake (health, financial, safety, and environment), according to the risk matrix of the organization. Define likelihood (i.e. probability) levels. Identify all project risks associated with performance reduction. The key performance indicators are injectivity, capacity and containment (any loss of performance may impact the stakes listed in 1.). Evaluate their likelihood and severity.
4680
Sorin Anghel / Energy Procedia 63 (2014) 4677 – 4683
5. 6.
7.
Place them in the Risk Matrix to identify scenario (hazard – event – consequence) with the highest criticity. Prepare mitigation plans to reduce likelihood and prevention plans to reduce severity to such levels that all the residual risks are within the acceptable levels for the organization (including local/ international regulations etc.) Review periodically as new information arrives
Fig. 1. General methodology for risk analysis
Likelihood POTENTIAL RISK
Ligh
1 Serious 2 Major 3 Catastrophic 4 Multi Catastrophic 5
↑
Very Low Medium low 1 2 3
O Severity→
Severity
MITIGATION Control measures PREVENTION ←
-1
LIKELIHOOD -2 -3
-2
-4
-3 -4 -5
High 4
Very High 5
→ -4
-5
-6
-8
-10
-6
-9
-12
-15
-8
-12
-16
-20
-20
-25
-10
-15
Potential risk matrix Fig.2 Potential risk matrix
4681
Sorin Anghel / Energy Procedia 63 (2014) 4677 – 4683
Likelihood RESIDUAL RISK EXTREME HIGH
-25 to -20 -19 to -10
Serious Major Catastrophic Multi Catastrophic
MEDIUM LOW Proceed carefuly INSIGNIFICANT Safe to proceed Very Low Medium High Very low High 1 2 3 4 5
O
← Ligh
↑
1 2 3 4 5
Severity→
Severity
-9 to -5 -4 to -2 -1 MITIGATION Control measures PREVENTION
Do not take this risk
-1
-2
-2
-4
-3 -4 -5
LIKELIHOOD -3
→ -4
-5
-6
-8
-10
-6
-9
-12
-15
-8
-12
-16
-20
-10
-15
-20
-25
Residual risk matrix Fig.3 Residual risk matrix
It is important to stress that risk analysis is a continuous and iterative process, and that more accurate information from appraisal, verification and monitoring can improve the knowledge of a storage site, and can therefore adjust the severity and likelihood defined for each risk, and can finally lead to an updated mitigation and prevention plan (including monitoring).Considering the availability of data and information available at this stage, and as stated above, only a preliminary risk assessment has been performed as part of this task, partly addressing steps 3 and 6 of the methodology described above and following the steps listed below: x Division of the subsurface at the storage sites into functional elements. x
Identification of the main hazards for each element.
x
For each of these hazards, identify the associated detectable (through monitoring) undesired event(s) that could result of their combination with injection of CO2 in the subsurface.
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Sorin Anghel / Energy Procedia 63 (2014) 4677 – 4683
x
Identify the potential direct and indirect consequences of these undesired events.
x
Identify prevention and mitigation measures that could be put in place to reduce the likelyhood and severity of the risks identified.
This exercise has been performed by conducting a workshop with the contribution of all subsurface team members involved in the project. 3. Study results 3.1 Hazards identification table Hazards have been referenced by the functional element to which they are associated: Reservoir, Caprock, Faults, CO2, Overburden, Underburden, and Wells. They have been classified according to the detectable undesired event that they could potentially lead to, in the context of CO2 injection in the subsurface. When a hazard can lead to several events, it has been repeated in the relevant sections of the table. A high level review of the potential consequences of each undesired event is provided in the column “Consequences”. It is understood that the consequences of the same event could be different, depending on the hazard which is causing this event. Nonetheless, as this is a preliminary exercise this fact has not been formally represented in the table. Finally, a high level screening of the potential prevention measures that could be put in place at different phases of the project (appraisal, construction, injection/monitoring) as well as mitigation measures are provided in the last column of the table. This clasification is not meant to be exhaustive but its objective is rather to highlight the most important technical risks associated to the project and plan accordingly for the next phases (in particular the appraisal). 3.2 Preliminary criticity analysis As mentioned before, due to the early stage of the project, a quantitative assessment of the risks has not been performed as part of this task. However, a preliminary analysis of the criticity of the risks associated with the identified hazards was conducted with the objective to highlight what were felt as the major concerns concerning the two candidate sites at this stage of the project. Again, the data currently available not allowing us to discriminate meaningfully between the two zones, this has been kept as a common exercise. The most critical hazards identified are presented in Table 1 below:
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Sorin Anghel / Energy Procedia 63 (2014) 4677 – 4683
Element
Hazard
Main Performance Factor impacted Containment
Reservoir
Insufficient lateral extent of pinch outs
Caprock
Unidentified conductive faults crossing caprock
Containment
Caprock
Unidentified fracture corridors crossing caprock
Containment
Caprock
Permeability underestimated
Containment
Wells
Existing P&A wells leaking
Containment
Faults
Unidentified faults within the reservoir not laterally transmissive
Faults
Bounding fault not sealing vertically* or laterally
Reservoir
Permeability lower than expected
Injectivity
Reservoir
Porosity lower than expected
Capacity
Reservoir
Plugging due to salting out around well
Injectivity
Capacity, Injectivity Containment
Table 1: Hazards with high perceived criticity * This looks to be more of an issue for zone 5 where the bounding faults are seen on existing 2D lines to extend higher than the top of caprock It can be seen that most of these hazards are associated to concerns about the containment of the future storage site. It can also be noted that the presence of most of these hazards in this list is due to the current lack of data available to the project and that thorough appraisal campaigns should be able to remove most of the uncertainty associated to these concerns. References [1] Anthonsen, K.L., P. Aagaard, P. E. S. Bergmo, M. Erlström, J.I. Fareide, S. R. Gislason, G. M. Mortensen, S. Ó. Snæbjörnsdottir, 2013. CO2 storage potential in the Nordic region. Energy Procedia 37, 5080 –5092. [2] Szizybalski, S., Kollersberger, T., Möller, F., Martens, S., Liebscher, A., Kühn, M. (2014): Communication Supporting the Research on CO2 Storage at the Ketzin Pilot Site, Germany - A Status Report after Ten Years of Public Outreach. Energy Procedia, 51, 2014, 274-280 [3] Eiken, O., Ringrose, P., Hermanrud, C., Nazarian, B., Torp T.A.,, Lars Høier L. Lessons learned from 14 years of CCS operations: Sleipner, In Salah and Snøhvit, Energy Procedia 4, 2011, 5541–5548. [4] Juhlin C., Ask M., Bjelm L., Elhami E., Erlström M., Joodaki S., Lazor P., Lorenz H., Niemi A., Rosberg J.E. and Sopher D.Potential for CO2 storage in Swedish bedrock: SwedSTORECO2 - Phase 1. Final Report, 125 pp. [5] Rütters, H. and the CGS Europe partners. State of play on CO2 geological storage in 28 European countries. CGS Europe report No. D2.10, June 2013. 1-89. [6] One North Sea: A study into North Sea cross-border CO2 transport and storage. 2010, http://www.npd.no/no/Publikasjoner/Rapporter/Samarbeider-om-CO2-lager/ [7] Haselton T. M. Exploiting the ROZ in Lithuania. Presented at the 19th Annual CO2 Flooding Conference, Midland, Texas, 14.12. 2013. http://www.co2conference.net/wp-content/uploads/2013/12/15-Haselton-Exploiting-the-ROZ-in-Lithuania-new-new.pdf [8] Poirot J. M. Technical risk assessment –CCS Storage project report-Schumberger