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To manage risks in CO2 storage operations, monitoring systems need to be designed such that the data can inform the operator whether the storage site will continue to behave as expected or not. In order to compare the benefits of different monitoring strategies, we require a measure of ‘efficiency' that is based on a balance between monitoring cost on the one hand and reliability of conformance determination on the other. In this work, we present a workflow to quantify, in terms of conformance verification metrics, the contribution of monitoring strategies with various time-lapse geophysical survey configurations (i.e., different survey acquisition times and coverage) in the presence of geological uncertainties. We illustrate the use of the methodology with a simple case study where conformance is associated with regulatory safety bounds for the development of the CO2 plume. The proposed approach can be used to assist operators in the design of monitoring strategies that can ensure compliance with regulation requirements at a reasonable cost. © 2018 European Association of Geoscientists and Engineers, EAGE. All rights reserved.

To manage risks in CO2 storage operations, monitoring systems need to be designed such that the data can inform the operator whether the storage site will continue to behave as expected or not. In order to compare the benefits of different monitoring strategies, we require a measure of ‘efficiency' that is based on a balance between monitoring cost on the one hand and reliability of conformance determination on the other. In this work, we present a workflow to quantify, in terms of conformance verification metrics, the contribution of monitoring strategies with various time-lapse geophysical survey configurations (i.e., different survey acquisition times and coverage) in the presence of geological uncertainties. We illustrate the use of the methodology with a simple case study where conformance is associated with regulatory safety bounds for the development of the CO2 plume. The proposed approach can be used to assist operators in the design of monitoring strategies that can ensure compliance with regulation requirements at a reasonable cost. © 2018 European Association of Geoscientists and Engineers, EAGE. All rights reserved.

Carbon dioxide Capture and Storage (CCS) is a promising contribution to reduce further increase of atmospheric CO2 emissions from fossil fuels. The CCS concept anticipates that large amounts of CO2 are going to be stored in the subsurface for the long term. Since CCS is a rather new technology, uncertainties related with the future evolution of a CO2 storage system should be addressed in a systematic framework. Performance and risk assessment frameworks are being created for the evaluation of the safeness and effectiveness of a CCS project. The recommended first step of this framework is a qualitative analysis, which encompasses the scenario analysis. The main goal of this step is to identify CO2 release scenarios, which can be supported by using a database of Features, Events and Processes (FEP), i.e. the elements that describe the characteristics and behaviour of the geological system. A qualitative FEP database tool assists to describe the storage concept and the factors which might influence the future behaviour of the storage reservoir and its surroundings. Scenario analysis using a FEP database is a crucial part of the risk assessment of a CCS project and has been applied to define release scenarios for a number of storage sites. However, further improvement is needed to facilitate a faster and more coherent analysis. For this purpose, a novel scenario analysis framework has been created, called Carbon Storage Scenario Identification Framework (CASSIF) (Yavuz et al., 2008 [1]). It is based on the three major CO2 release scenarios (well, fault and seal) from where the relevant events and processes are identified and modelled. Expert opinion is a key value within this framework. A questionnaire to be filled in by experts has been designed for the initial screening and ranking of events and processes. Features (static entities) have been separated from the events and process (the dynamic characteristics) so the focus in the expert elicitation will be on the latter. The new interface facilitates the online use of the FEP database. Together with real-time scenario formation, these improvements will greatly enhance the speed, transparency and comprehe nsiveness in the creation of subsurface CO2 release scenarios. © 2009 Elsevier Ltd. All rights reserved.

A multidisciplinary study has been carried out in Hontomín (Spain) to determine the basement structural setting, its geometry and the geometry of the sedimentary succession of an area aimed to be the first Spanish pilot plant for CO2 storage. An integration of coincident 3-D seismic results, borehole data and unpublished microgravity data were used to reproduce the deep structure and topography of the basement and to quantify the thickness of the Triassic Keuper evaporites. The subsurface structure is characterized by a half-graben setting filled with Keuper evaporites (up to 2000m thick), forming an extensional forced fold. All data sets clearly identify two main fault systems, compartmentalizing the main structural domain into three differentiated blocks. These faults have been interpreted to be reactivated normal faults that have led to the formation of the Hontomín dome. © Author(s) 2016., The data sets in this work have been funded by Fundación Ciudad de la Energía (Spanish Government, www.ciuden.es) and by the European Union through the “European Energy Programme for Recovery” and the Compostilla OXYCFB300 project. Juan Alcalde is currently funded by NERC grant NE/M007251/1.

This paper reports on the regional screening, selection and geological characterisation of a potential on-shore CO2 storage site (saline aquifer) in north-eastern Germany. The main objective of this study was to identify and investigate a candidate storage site, capable to accommodate the total amount of approximately 400 million tons of CO2. Such a volume is produced by a modern, lignite-fired power plant within its operation lifetime of approximately 40 years. Within north-eastern Germany, several saline aquifers of Triassic, Jurassic and Cretaceous age have been evaluated with respect to their regional occurrence, storage potential and basic reservoir properties. Subsequent to a ranking, considering different criteria, the anticlinal structure Schweinrich holding suitable saline aquifers of the uppermost Triassic and lowest Jurassic has been selected from a number of identified candidate sites. According to results of the geological site characterisation, including structural geological investigations and 3D reservoir modelling, the structure Schweinrich seems to be a suitable site for industrial large scale CO2 storage. Further data acquisition (new wells and 3D seismics) and research (more detailed and comprehensive modelling) is needed in order to prove the structural integrity of the storage site and assure long-term safety. © 2007 Springer-Verlag.

Conference paper The scheduling of workflow applications involves the mapping of individual workflow tasks to computational resources, based on a range of functional and non-functional quality of service requirements. Workflow applications such as scientific workflows often require extensive computational processing and generate significant amounts of experimental data. The emergence of cloud computing has introduced a utility-type market model, where computational resources of varying capacities can be procured on demand, in a pay-per-use fashion. In workflow based applications dependencies exist amongst tasks which requires the generation of schedules in accordance with defined precedence constraints. These constraints pose a difficult planning problem, where tasks must be scheduled for execution only once all their parent tasks have completed. In general the two most important objectives of workflow schedulers are the minimisation of both cost and make span. The cost of workflow execution consists of both computational costs incurred from processing individual tasks, and data transmission costs. With scientific workflows potentially large amounts of data must be transferred between compute and storage sites. This paper proposes a novel cloud workflow scheduling approach which employs a Markov Decision Process to optimally guide the workflow execution process depending on environmental state. In addition the system employs a genetic algorithm to evolve workflow schedules. The overall architecture is presented, and initial results indicate the potential of this approach for developing viable workflow schedules on the Cloud. Science Foundation Ireland non-peer-reviewed

The largest single point CO2 emitter in Ireland, the Moneypoint Power Station (3.95 Mt CO2 per annum), is located in Co. Clare and geologically lies within the Clare Basin. In terms of the economics of transportation of CO2 from Moneypoint, a possible local storage site would be favoured. The study investigated a number of critical criteria with respect to potential geological storage of CO2 within the onshore portion of the Clare Basin. In a screening study of this nature, the objective is to search for subsurface reservoirs that have sufficient storage capacity, good injection properties and sufficient confining potential. These properties depend on a number of geological parameters for each of the targeted formations. Reservoir size (CO2 storage capacity) depends on, among other factors, the pore volume that is available and reservoir depth. The rate at which CO2 can be injected into the reservoir is determined by the permeability and thickness of the reservoir formation(s). Confining potential depends on the seal rock type, thickness, the presence of faults and the type of trap structures. Other geological properties that are relevant for aquifer size, injectivity and seal quality also need to be considered in site characterisation studies. This study examined these key parameters using a modular approach. Extensive data collection was followed by several interpretational programmes including a detailed re-logging programme of deep historical boreholes to maximise the sub-surface data available to the project. The resultant datasets were assimilated into a Petrel geological model for the area. Two boreholes were completed at key sites within the Clare Basin. A primary objective of the drilling programme was to provide fresh material for porosity/permeability test work. Results from the rock characterisation studies were integrated into the geological model. This allowed a final assessment of the potential storage volume and suitability, revealing that the onshore portion of the Clare Basin is unsuitable for CO2 storage. © 2011 Published by Elsevier Ltd.

The largest single point CO2 emitter in Ireland, the Moneypoint Power Station (3.95 Mt CO2 per annum), is located in Co. Clare and geologically lies within the Clare Basin. In terms of the economics of transportation of CO2 from Moneypoint, a possible local storage site would be favoured. The study investigated a number of critical criteria with respect to potential geological storage of CO2 within the onshore portion of the Clare Basin. In a screening study of this nature, the objective is to search for subsurface reservoirs that have sufficient storage capacity, good injection properties and sufficient confining potential. These properties depend on a number of geological parameters for each of the targeted formations. Reservoir size (CO2 storage capacity) depends on, among other factors, the pore volume that is available and reservoir depth. The rate at which CO2 can be injected into the reservoir is determined by the permeability and thickness of the reservoir formation(s). Confining potential depends on the seal rock type, thickness, the presence of faults and the type of trap structures. Other geological properties that are relevant for aquifer size, injectivity and seal quality also need to be considered in site characterisation studies. This study examined these key parameters using a modular approach. Extensive data collection was followed by several interpretational programmes including a detailed re-logging programme of deep historical boreholes to maximise the sub-surface data available to the project. The resultant datasets were assimilated into a Petrel geological model for the area. Two boreholes were completed at key sites within the Clare Basin. A primary objective of the drilling programme was to provide fresh material for porosity/permeability test work. Results from the rock characterisation studies were integrated into the geological model. This allowed a final assessment of the potential storage volume and suitability, revealing that the onshore portion of the Clare Basin is unsuitable for CO2 storage. © 2011 Published by Elsevier Ltd.

Analysis of Factors that Affect Uncertainty in Predictions of Carbon Dioxide Capture and Storage in Croatia

Fe promoted NOx storage materials were synthesized in the form of FeOx/BaO/Al2O3 ternary oxides with varying BaO (8 and 20 wt %) and Fe (5 and 10 wt %) contents. Synthesized NOx storage materials were investigated via TEM, EELS, BET, FTIR, TPD, XRD, XPS, and Raman spectroscopy, and the results were compared with the conventional BaO/Al2O3 NOx storage system. Our results suggest that the introduction of Fe in the BaO/Al2O3 system leads to the formation of additional NOx storage sites which store NOx mostly in the form of bidentate nitrates. NO2 adsorption experiments at 323 K via FTIR indicate that, particularly in the early stages of the NOx uptake, the NOx storage mechanism is significantly altered in the presence of Fe sites where a set of new surface nitrosyl and nitrite groups were detected on the Fe sites and the surface oxidation of nitrites to nitrates is significantly hindered with respect to the BaO/Al2O3 system. Evidence for the existence of both Fe3+ as well as reduced Fe2+/(3-x)+ sites on the freshly pretreated materials was detected via EELS, FTIR, Raman, and XRD experiments. The influence of the Fe sites on the structural properties of the synthesized materials was also studied by performing ex situ annealing protocols within 323-1273 K followed by XRD and Raman experiments where the temperature dependent changes in the morphology and the composition of the surface domains were analyzed in detail. On the basis of the TPD data, it was found that the relative stability of the stored NOx species is influenced by the morphology of the Ba and Fe containing NOx-storage domains. The relative stabilities of the investigated NOx species were found to increase in the following order: N2O3/NO+ < nitrates on γ-Al2O3 < surface nitrates on BaO < bidentate nitrates on FeOx sites < bulk nitrates on BaO.

CO2 storage in the subsurface is becoming more and more attractive as a means to reduce CO2 emissions to the atmosphere and hence minimize human-induced global warming. The ability to monitor and verify these CO2 storage reservoirs is a key element for further implementation of other storage sites. Since the current sites fortunately do not appear to "leak" CO2, it is difficult to test the most suitable monitoring techniques for their ability to detect CO2 migration pathways. In this study different monitoring methods have been evaluated at a site in the Latera caldera (central Italy) where natural, thermo-metamorphically produced CO2 finds its way to the surface. The aim of the study is to identify which monitoring methods can detect the migrating CO2 and to gain understanding of the preferential migration pathways of the CO2. Different geophysical monitoring techniques have been deployed at a small, 200×500 m study area located in the centre of the caldera: 2D reflection seismics (testing different sources), 2D refraction seismics, multi-channel analysis of surface wave (MASW), ground penetrating radar (GPR), micro-gravity, magnetometer, self-potential (SP), 2D and 3D geo-electrical measurements and electro-magnetic (EM31 and EM34) measurements. Furthermore CO2 flux measurements were performed in a dense grid over the study area, and a limited number of soil gas samples collected along two profiles, to "ground-truth" the geophysical results. In general a good correlation has been observed between the different methods and the presence of CO2. Geophysical responses, especially those of the reflection seismic and magnetometer data, change markedly from one side of the proposed main fault to the other, probably linked to a sharp geological boundary. The observed fractures on the seismic data seem to correspond with the preferred migration pathways of the CO2. The GPR and resistivity measurements detect strong variations in conductivity induced by the presence of the CO2 up to about 2 and 20 m depth, respectively, as supported by the soil gas and flux measurements. © 2009 Elsevier Ltd. All rights reserved.

The minimum injection depth for the storage of CO2 is normally set at 800 metres. At and beyond this depth in the subsurface conditions exist where CO2 is in a so-called critical state. The supercritical CO2 has a viscosity comparable to that of a normal gas and a liquid-like density, Due to the high density of the supercritical CO2, storing the CO2 in the supercritical state is the most efficient geological storage. The CO2 will therefore be injected below the transition zone between subcritical and supercritical conditions. In the case of CO2 storage in large aquifers, some part of the storage formation may lie at shallower depths where CO2 occurs in gas phase. The CO2 will also occur in the subcritical state (gas phase) in the case of an unintentional CO2 leak from an existing storage site. In both cases it is crucial to understand how the CO2 will behave when it reaches and passes this transition zone. In the case of intentional CO2 injection in a shallow aquifer this knowledge is important to determine both the injection strategy and the available storage capacity of the aquifer; in the case of leakage, safety and risk assessment. In this paper we present the results of a reservoir simulation study, supported by a literature study, that considers the principles of CO2 phase behaviour in the subsurface, and the implications for the injection strategy and storage volumes. © 2009 Elsevier Ltd. All rights reserved.

The minimum injection depth for the storage of CO2 is normally set at 800 metres. At and beyond this depth in the subsurface conditions exist where CO2 is in a so-called critical state. The supercritical CO2 has a viscosity comparable to that of a normal gas and a liquid-like density, Due to the high density of the supercritical CO2, storing the CO2 in the supercritical state is the most efficient geological storage. The CO2 will therefore be injected below the transition zone between subcritical and supercritical conditions. In the case of CO2 storage in large aquifers, some part of the storage formation may lie at shallower depths where CO2 occurs in gas phase. The CO2 will also occur in the subcritical state (gas phase) in the case of an unintentional CO2 leak from an existing storage site. In both cases it is crucial to understand how the CO2 will behave when it reaches and passes this transition zone. In the case of intentional CO2 injection in a shallow aquifer this knowledge is important to determine both the injection strategy and the available storage capacity of the aquifer; in the case of leakage, safety and risk assessment. In this paper we present the results of a reservoir simulation study, supported by a literature study, that considers the principles of CO2 phase behaviour in the subsurface, and the implications for the injection strategy and storage volumes. © 2009 Elsevier Ltd. All rights reserved.

Carbon dioxide Capture and Storage (CCS) is a promising contribution to reduce further increase of atmospheric CO2 emissions from fossil fuels. The CCS concept anticipates that large amounts of CO2 are going to be stored in the subsurface for the long term. Since CCS is a rather new technology, uncertainties related with the future evolution of a CO2 storage system should be addressed in a systematic framework. Performance and risk assessment frameworks are being created for the evaluation of the safeness and effectiveness of a CCS project. The recommended first step of this framework is a qualitative analysis, which encompasses the scenario analysis. The main goal of this step is to identify CO2 release scenarios, which can be supported by using a database of Features, Events and Processes (FEP), i.e. the elements that describe the characteristics and behaviour of the geological system. A qualitative FEP database tool assists to describe the storage concept and the factors which might influence the future behaviour of the storage reservoir and its surroundings. Scenario analysis using a FEP database is a crucial part of the risk assessment of a CCS project and has been applied to define release scenarios for a number of storage sites. However, further improvement is needed to facilitate a faster and more coherent analysis. For this purpose, a novel scenario analysis framework has been created, called Carbon Storage Scenario Identification Framework (CASSIF) (Yavuz et al., 2008 [1]). It is based on the three major CO2 release scenarios (well, fault and seal) from where the relevant events and processes are identified and modelled. Expert opinion is a key value within this framework. A questionnaire to be filled in by experts has been designed for the initial screening and ranking of events and processes. Features (static entities) have been separated from the events and process (the dynamic characteristics) so the focus in the expert elicitation will be on the latter. The new interface facilitates the online use of the FEP database. Together with real-time scenario formation, these improvements will greatly enhance the speed, transparency and comprehe nsiveness in the creation of subsurface CO2 release scenarios. © 2009 Elsevier Ltd. All rights reserved.

This paper reports on the regional screening, selection and geological characterisation of a potential on-shore CO2 storage site (saline aquifer) in north-eastern Germany. The main objective of this study was to identify and investigate a candidate storage site, capable to accommodate the total amount of approximately 400 million tons of CO2. Such a volume is produced by a modern, lignite-fired power plant within its operation lifetime of approximately 40 years. Within north-eastern Germany, several saline aquifers of Triassic, Jurassic and Cretaceous age have been evaluated with respect to their regional occurrence, storage potential and basic reservoir properties. Subsequent to a ranking, considering different criteria, the anticlinal structure Schweinrich holding suitable saline aquifers of the uppermost Triassic and lowest Jurassic has been selected from a number of identified candidate sites. According to results of the geological site characterisation, including structural geological investigations and 3D reservoir modelling, the structure Schweinrich seems to be a suitable site for industrial large scale CO2 storage. Further data acquisition (new wells and 3D seismics) and research (more detailed and comprehensive modelling) is needed in order to prove the structural integrity of the storage site and assure long-term safety. © 2007 Springer-Verlag.