Seismological tools for geothermal exploration and monitoring

• Main Author: Toledo Zambrano, Tania Andrea
• Other Authors: Krawczyk, Charlotte, Jousset, Philippe, Technische Universität Berlin, Maurer, Hansruedi, Brehme, Maren
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2021
• Subjects: 550 Geowissenschaften; Geothermal exploration; geothermal energy; seismology; seismic imaging; seismic monitoring; geothermische Erkundung; geothermische Energie; Seismologie; seismische Bildgebung; seismische Überwachung; Reykjanes; Iceland
• Online Access: https://depositonce.tu-berlin.de/handle/11303/13057; https://doi.org/10.14279/depositonce-11853

Important aspects of geothermal exploration and exploitation are the assessment and mitigation of natural and/or induced seismicity, the imaging and resource assessment of a geothermal reservoir and the monitoring of the effects of the exploitation activities. With this thesis the analysis and application of various seismological tools for the planning, exploration, and monitoring of geothermal fields are given. The methods explored and further developed include survey design for microseismic network construction and assessment, local earthquake tomography, ambient noise tomography, and coda wave interferometry. These techniques were applied to study Los Humeros (Mexico), Theistareykir (Iceland) and Reykjanes (Iceland) geothermal fields. The geometry of seismological arrays is essential for high quality seismic event retrieval and minimal location errors. A sequential survey design algorithm that uses a quality measure based on the D-criterion was applied to extend the seismic network at Theistareykir and to qualify the geometry of the Reykjanes network. Assuming mean picking errors of tp =0.2 s and ts = 0.4 s, the extended Theistareykir network presented an improvement of ∼0.2 km for the computed hypocentral components of seismic events located within the new network. Conversely, we estimated that the Reykjanes network could spare up to 18 of its station locations and obtain comparable location errors nonetheless. This study showed thei mportance of prior survey design experiments to optimize the expenses for a geothermal project (required number of sensors) while obtaining good location estimates of expected seismic events (benefit/cost relations). To characterize the seismic structures at Los Humeros and Theistareykir geothermal fields, a local earthquake tomography and an ambient noise tomography were computed at both locations, respectively. A local earthquake tomography is feasible in areas with high seismicity and good ray coverage (earthquake/station geometries). On the other hand, an ambient noise ...