An active tectonic field for CO<sub>2</sub> storage management: the Hontomín onshore case study (Spain)

Abstract

Abstract. One of the concerns of underground CO2 onshore storage is the triggering of induced seismicity and fault reactivation by the pore pressure increasing. Hence, a comprehensive analysis of the tectonic parameters involved in the storage rock formation is mandatory for safety management operations. Unquestionably, active faults and seal faults depicting the storage bulk are relevant parameters to be considered. However, there is a lack of analysis of the active tectonic strain field affecting these faults during the CO2 storage monitoring. The advantage of reconstructing the tectonic field is the possibility to determine the strain trajectories and describing the fault patterns affecting the reservoir rock. In this work, we adapt a methodology of systematic geostructural analysis to underground CO2 storage, based on the calculation of the strain field from kinematics indicators on the fault planes (ey and ex for the maximum and minimum horizontal shortening, respectively). This methodology is based on a statistical analysis of individual strain tensor solutions obtained from fresh outcrops from the Triassic to the Miocene. Consequently, we have collected 447 fault data in 32 field stations located within a 20 km radius. The understanding of the fault sets' role for underground fluid circulation can also be established, helping further analysis of CO2 leakage and seepage. We have applied this methodology to Hontomín onshore CO2 storage facilities (central Spain). The geology of the area and the number of high-quality outcrops made this site a good candidate for studying the strain field from kinematics fault analysis. The results indicate a strike-slip tectonic regime with maximum horizontal shortening with a 160 and 50∘ E trend for the local regime, which activates NE–SW strike-slip faults. A regional extensional tectonic field was also recognized with a N–S trend, which activates N–S extensional faults, and NNE–SSW and NNW–SSE strike-slip faults, measured in the Cretaceous limestone on top of the Hontomín facilities. Monitoring these faults within the reservoir is suggested in addition to the possibility of obtaining a focal mechanism solutions for micro-earthquakes (M<3).

Active Faults, Kinematics, and Seismotectonic Evolution during Tajogaite Eruption 2021 (La Palma, Canary Islands, Spain)

“…The advantage of applying these methods is that they make it possible to discriminate regional deformation fields, resulting from large tectonic structures such as oceanic ridges or continental collision zones, for example, from local deformation fields resulting from specific volcanic phenomena or the emplacement of magmatic dikes. As for the study of deformation due to regional fields, [31] applies the same methodology in large areas, while [32] applies it to local cases of induced seismicity associated with the injection of fluids, which could be comparable to the injection of magma on previous structures.…”

Impact of Regional Pressure Dissipation on Carbon Capture and Storage Projects: A Comprehensive Review

“…Most of the concerns revolve around the possibility of causing significant observable seismic events and how these events might affect both the long-term stability of a carbon dioxide (CO 2 ) storage site and public perceptions of GCS (see Figure 6) [151]. The Hontomín CCS project in Spain exemplifies how advanced seismicity analysis can inform operational decisions [153]. By studying seismic events in conjunction with pressure data, project operators established thresholds beyond which injection rates were reduced or halted temporarily.…”

“…To tackle these challenges, comprehensive investigation and monitoring strategies are imperative. Pressure monitoring networks, geomechanical modelling, and advanced The Hontomín CCS project in Spain exemplifies how advanced seismicity analysis can inform operational decisions [153]. By studying seismic events in conjunction with pressure data, project operators established thresholds beyond which injection rates were reduced or halted temporarily.…”

Discontinuities Characterization and Estimation of the Geological Strength Index by AI Tools on Flysch Materials

“…The Lower Jurassic dolostones act as a reservoir for the CO2 geological storage pilot plant of Hontomín in the southernmost portion of the Basque-Cantabrian Basin (e.g. [46]). The second rift phase starts with the deposition of Urgonian reef limestones with intercalations of sandstones, claystones and marlstones of Aptian to Early Albian in age.…”