Critical technology elements (WP1)

The overall objective of the DigiMon project is to “accelerate the implementation of CCS by developing and demonstrating an affordable, flexible, societally embedded and smart Digital Monitoring early warning system”, for monitoring any CO2 storage reservoir and subsurface barrier system. Within the project the objective of WP1 was to develop individual technologies, data acquisition, analysis techniques and workflows in preparation for inclusion in the DigiMon system. The technologies and data processing techniques developed as part of WP1 include distributed fibre-optic sensing (DFOS) for seismic surveys and chemical sensing, 4D gravity and seafloor deformation measurements, a new seismic source and seismic monitoring survey design. For these technologies the key targets for WP1 were • Develop individual components of the system to raise individual technology readiness levels (TRLs), • Validate and optimise processing software for individual system components, • Develop an effective Distributed Acoustic Sensing (DAS) data interpretation workflow. This work was performed with the expected outcomes of • Raising the DAS TRL for passive seismic monitoring, • An assessment the feasibility of using Distributed Chemical Sensing (DCS) for CO2 detection, • Reducing the cost of 4D gravity and seafloor deformation measurements

Hydrothermal fluids and where to find them:Using seismic attenuation and anisotropy to map fluids beneath Uturuncu volcano, Bolivia

Mapping fluid accumulation in the crust is pertinent for numerous applications including volcanic hazard assessment, geothermal energy generation, and mineral exploration. Here, we use seismic attenuation tomography to map the distribution of fluids in the crust below Uturuncu volcano, Bolivia. Seismic P wave and S wave attenuation, as well as their ratio (QP/QS), constrain where the crust is partially and fully fluid-saturated. Seismic anisotropy observations further constrain the mechanism by which the fluids accumulate, predominantly along aligned faults and fractures in this case. Furthermore, subsurface pressure-temperature profiles and conductivity data allow us to identify the most likely fluid composition. We identify shallow regions of both dry and H2O/brine-saturated crust, as well as a deeper supercritical H2O/brine column directly beneath Uturuncu. Our observations provide a greater understanding of Uturuncu's transcrustal hydrothermal system, and act as an example of how such methods could be applied to map crustal fluid pathways and hydrothermal/geothermal systems elsewhere