Interdisciplinary and transdisciplinary collaboration has become a common practice in technology development projects. Rarely, however, the integration (and translation) of knowledge from different disciplines and different societal contexts is reported in detail. In this article, we address this gap and present the inter- and transdisciplinary technology development in the international research project “DigiMon—Digital Monitoring of CO₂ Storage Projects” that aims to develop a human-centered monitoring system. Based on interviews, surveys and stakeholder workshops in Norway, Greece, Germany and The Netherlands, we identify characteristics of CO₂ storage monitoring systems that reflect the concerns and expectations of publics and stakeholders. We document the translation of social scientific findings into technical expertise for the design of a monitoring system. We discuss how the interdisciplinary and transdisciplinary process has affected the technology development. In outlining how this process was set up, carried out and validated, we are able to show a viable route for the meaningful incorporation of heterogeneous knowledge in complex energy infrastructures. Furthermore, we discuss the features of the project organization that made this comprehensive process possible. Thus, our results contribute to inter- and transdisciplinary research organization in general and to the development of methods for monitoring CO₂ storage in particular.

I evaluated a simultaneous joint inversion of seismic amplitude-versus-offset (AVO) and controlled-source electromagnetic (CSEM) data for fluid-flow monitoring. A new approach for structure-coupled joint inversion was presented, in which the coupling of the two data types was obtained by allowing for the direct identification of parameter structure that is shared by the different geophysical model parameters. The main idea was to use a composite parameter representation, which enables inversion with respect to the parameter magnitude and parameter structure. In the current application, parameter structure refers to transitions between dominating property values and is represented by the position and shape of the flooding front. Hence, with this approach, the position and shape of the flooding front are inverted for directly, and the coupling between the different data sets is obtained without the inclusion of an additional penalizing term in the objective function. Regularization of the inverse problem is obtained by using a flexible parameterization grid adapted to the resolution power of the available data. This approach is especially suited for problems in which the prior information is limited or highly uncertain. The solution approach is illustrated for two types of coupling: (1) identification of fluid saturation using rock-physics modeling and (2) for structure-coupled joint inversion with respect to P-wave velocity and electric conductivity. Through various synthetic examples in 2D, the proposed approach showed its efficiency for identifying the main features of the fluid distribution within the reservoir. Simultaneously inverting AVO and CSEM data was further seen to give results that were more robust with respect to certain random and more systematic (modeling) errors compared with inverting the data sets separately.

The technical objective of a monitoring system is to provide the means to detect potential irregularities related to the project plan, to provide assurance that the migration of the CO₂ plume stays within the storage unit, and to show that CO₂ behaves in conformance with the model predictions. From an operational point of view, monitoring will also provide data that can be used to optimize the injection schedule relative to the storage capacity and availability of CO₂ to minimize risks and long-term costs. Finally, monitoring is a crucial factor for the public perception of risks related to CO₂ storage, as surveys indicate that adequately designed monitoring can mitigate concerns. The Analytical Hierarchy Process (AHP) is a holistic, transdisciplinary, multi-criteria decision-making framework. The objective of this work is to apply the AHP framework to monitoring-solutions for a synthetic geological storage site of CO₂ to secure the technical, operational, and societal embeddedness of the solutions and gain experience in how this can be applied to a real project. Through this first application of AHP within the field of geological carbon storage, the AHP was found to be a structured and transparent framework for holistic, multi-criteria decision-making (MCDM), where the wisdom and expertise of different domain experts were considered. A further novelty in this study is introducing a measure of spread in assessing the various solution alternatives’ capacity to meet monitoring criteria. This approach was utilized to underscore disparities among respondents’ experiences and to identify potential informational deficiencies in evaluating alternatives and devising the optimal monitoring solution.

Monitoring slow earthquake activity in subduction zones can give important insight into the stress build-up and subsequent rupture extent of megathrust earthquakes. Extensive slow earthquake activity occurs up-dip of the seismogenic zone of the Nankai Trough subduction zone, an area that might be awaiting a large (M _w {greater than or equal to}8) earthquake in the near future. Mechanisms used to explain the occurrence of slow earthquakes are often linked to temporal changes in fluid transport along faults. This study utilises this theory in evaluating the usage of 4D gravity measurements on the seafloor for monitoring changes in fluid flow, hence monitoring the slow earthquake activity and the mechanisms behind them. We model the gravity response from fluid-related density changes in an area of the Nankai Trough accretionary prism that experiences several slow earthquake episodes in the interseismic period. The forward modelled 4D gravity response is used to estimate volumes of fluid at specific locations of the accretionary prism and plate interface corresponding to a minimum gravity signal of 5 µGal. This accuracy in the gravity signal is obtainable through technology monitoring micro-gravity effects at the seafloor. Based on the results we have formulated a hypothesis on how small fluid volume changes can be detected through a gravimetry survey at the seafloor of the Nankai Trough. The results can also be used to design a survey layout for obtaining valuable 4D gravity data at the Nankai Trough.