The subsurface provides multiple resources, the exploitation of which has a lasting impact on future potential provision. Establishing sustainability in terms of fundamental principles, and fitting these principles into a practical framework, is an ongoing endeavour focused mainly on surface activities. The principles of ecological economics lead to six challenges that summarize the current limitations of implementing science-based sustainable management of geological resources in the medium to deep subsurface: integrating value pluralism, defining sustainable scale, evaluating interferences in the subsurface, guaranteeing environmental justice, optimizing environmental and economic efficiency and handling uncertainties. Assessing and managing geological reservoirs is particularly challenging because of slow resource regeneration, complex spatial and temporal inter-actions, concealment and naturally dictated opportunities. In answer to the challenges, visions are proposed that outline how an indicator framework is needed for guidance, how indicators require reservoir models with extended spatial and temporal scope, how differences in social values in relation to the environment are to be considered and how real option games combined with life cycle assessment can be used for optimizing effi-ciency. These individual solutions relate to different facets of the same problem, and can be integrated into one overarching solution that takes the form of dynamic multi-criteria decision analysis.

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The use of anthropogenic CO2 for enhancing oil recovery from mature oil fields in the North Sea has several potential benefits, and a number of assessments have been conducted. It remains, however, difficult to realistically simulate the economic circumstances and decisions, while including the economic uncertainties that surround the relevant markets and policies, and the geological and technological uncertainties that are inherent to dealing with reservoirs and novel technologies in a challenging environment. A new method is proposed here introducing a unique combination of innovations, that include true limited foresight, project flexibility, and the consideration of realistic investment risk. The value of project is here expressed as the Net Present Value (NPV). These elements are combined in the PSS IV simulator. This is a techno-economic simulator for CO2-enhanced oil recovery (CO2-EOR), which applies limited foresight and Real Options Analysis to make realistic investment decisions on projects with significant uncertainties and thus risk. Consecutive project decisions are taken based on a decision tree. Multiple oil fields can be approached as a single cluster project, which can provide a lower investment hurdle. In a first test case for PSS IV, the Claymore and Scott oil fields are assessed, and it is shown that economic simulations where EOR projects are regarded as a sum of the individual field assessments will undervalue projects. Simulation results show that results are in a realistic range compared to published numbers, with individual project values for the Claymore field on average of 15.8 €/barrel (bbl; standard deviation SD = 8.3) and for the Scott field of 14.3 €/bbl (SD = 8.6). Due to the inclusion of uncertainties and the application of limited foresight, results range from −6 €/bbl (loss) to over 30 €/bbl. In a cluster configuration 5 €/bbl of additional value is created.@en

Carbon dioxide capture and geological storage (CCS) is a means to drastically reduce greenhouse gas emissions. This paper shows an application to the Austrian context of a newly developed methodology for the assessment of geological reservoirs, based on expert opinions on the Schönkirchen Tief, Höflein, Schönkirchen Übertief, Reyersdorfer Dolomite, Aderklaa, Atzbach-Schwanenstadt and Voitsdorf reservoirs. Because of a lack in reservoir-specific research for the storage of CO, large uncertainties on the behaviour and use of the Austrian reservoirs exist. Therefore the potential of the reservoirs remains unknown.2 Geological, technological and economic simulations are performed which integrate different uncertainties. The results show that there is a significant potential for CO storage in Austria. The total practical and matched capacity for Austria is assessed at about 120 and 40 MtCO respectively. An exploration2 priority ranking, based on reservoir development probability, shows that the Schönkirchen Übertief reservoir2 has the highest potential for storage and should be a primary target for further exploration.@en

CO₂-enhanced oil recovery (CO₂-EOR) has the potential to combine the environmental benefits of greenhouse gas emission reduction and the optimal use of natural resources. In economic simulations, CO₂-EOR is generally approached in a classical way, with fixed parameters and limited flexibility. We propose a more realistic approach that combines realistic investment decision making with geological and techno-economic uncertainties. A cluster of seven active oil fields in the North Sea is simulated using a newly developed software tool, allowing to assess when EOR technology replaces primary production. CO₂ can be delivered from different onshore locations via ship or pipeline. The introduction of near-realistic investment geological and economic risks in CO₂-EOR projections will allow for in-depth assessment of CO₂-EOR at the level of the North-Sea Basis, as well as of individual potential projects.

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CO2 capture and storage (CCS) is likely to become a necessary option in mitigating global climate change. However, lack of detailed knowledge on potential deep geological reservoirs can hamper the development of CCS. In this paper a new methodology is presented to assess and create exploration priority lists for poorly known reservoirs. Geological expert judgements are used as a basis in a two-stage geo-techno-economic approach, where first an estimate of the practical reservoir capacity is calculated, and secondly source-sink matching is used for calculating an estimate of the matched capacity and the reservoir development probability. This approach is applied to Belgium, demonstrating how a priority ranking for reservoirs can be obtained based on limited available data and large uncertainties. The results show the Neeroeteren Formation as the most prospective reservoir, followed by the Buntsandstein Formation and the Dinantian reservoirs. The findings indicate that CO2 export to reservoirs in neighbouring countries seems inevitable; still, there is a 70% chance storage will happen in Belgian reservoirs, with an average matched capacity estimate of 110Mt CO2. These quantitative results confirm the qualitative resource pyramid classification of potential reservoirs. For Belgium, a high economic risk is attached to reservoir exploration and development. Exploration remains however a necessity if CCS is to be deployed. Furthermore, it is shown that the presented methodology is indeed capable of producing realistic results, and that using expert judgements for reservoir assessments is valid and beneficial.@en