Mission Statement

The Geothermal Energy & Geofluids group is endowed by the Werner Siemens Foundation and investigates reactive fluid (water, CO2, CxHy, N2) and (geothermal) energy (heat, pressure) transfer in the Earth’s crust employing computer simulations, laboratory experiments and field analyses to gain fundamental insights and to address a wide range of societal goals and concerns. ➞ Read More

wss logo

GEG News


January 2024

Rock Mechanics Bulletin Excellent Paper 2022-2023 Award

A GEG paper receives the Rock Mechanics Bulletin Excellent Paper 2022-2023 Award. The paper is:

Li, Z., X. Ma, X.-Z. Kong, M.O. Saar, and D. Vogler, Permeability evolution during pressure-controlled shear slip in saw-cut and natural granite fractures, Rock Mechanics Bulletin, 2023. https://doi.org/10.1016/j.rockmb.2022.100027 [Download] [View Abstract]Fluid injection into rock masses is involved during various subsurface engineering applications. However, elevated fluid pressure, induced by injection, can trigger shear slip(s) of pre-existing natural fractures, resulting in changes of the rock mass permeability and thus injectivity. However, the mechanism of slip-induced permeability variation, particularly when subjected to multiple slips, is still not fully understood. In this study, we performed laboratory experiments to investigate the fracture permeability evolution induced by shear slip in both saw-cut and natural fractures with rough surfaces. Our experiments show that compared to saw-cut fractures, natural fractures show much small effective stress when the slips induced by triggering fluid pressures, likely due to the much rougher surface of the natural fractures. For natural fractures, we observed that a critical shear displacement value in the relationship between permeability and accumulative shear displacement: the permeability of natural fractures initially increases, followed by a permeability decrease after the accumulative shear displacement reaches a critical shear displacement value. For the saw-cut fractures, there is no consistent change in the measured permeability versus the accumulative shear displacement, but the first slip event often induces the largest shear displacement and associated permeability changes. The produced gouge material suggests that rock surface damage occurs during multiple slips, although, unfortunately, our experiments did not allow quantitatively continuous monitoring of fracture surface property changes. Thus, we attribute the slip-induced permeability evolution to the interplay between permeability reductions, due to damages of fracture asperities, and permeability enhancements, caused by shear dilation, depending on the scale of the shear displacement.

 



10.03.2023

Doctoral Examination Batmagnai Erdenechimeg

On March 3, 2023, Batmagnai Erdenechimeg has successfully defended his PhD thesis, entitled: “Magnetotelluric exploration of intermediate temperature geothermal systems and mineral resources in central Mongolia”.


31.01.2023

Dr. Paromita Deb – Heitfeld Award

December 2022, RWTH Aachen
Dr. Paromita Deb has been given the Dr. Karl-Heinrich Heitfeld Award for the best doctoral thesis in the Division of Earth Sciences and Geography.
Read more – link to RWTH Aachen


31.10.2022

Doctoral Examination Isamu Naets

On October 28, 2022, Isamu Naets has successfully defended his PhD thesis, entitled: “A pore scale investigation of fluid flow heterogeneity and solute transport in rough-walled fractures”.


30.10.2022

Ending EGC2022 with great results and a new destination for EGC2025 in Zurich

The biggest geothermal event in Europe has ended. More than 1300 participants attended EGC2022. The next EGC2025 will be held in Zurich, from 6 to 10 October 2025, organized by Geothermie Schweiz and co-organized by ETH Zurich.


19.09.2022

Doctoral Examination Po-Wei Huang


On September 16th, 2022, Po-Wei Huang has successfully defended his PhD thesis, entitled: “Reactive transport modeling at the pore scale and upscaling to the Darcy scale”.



Videos


CO2-Plume Geothermal (CPG) power plants combine geologic CO2 storage with geothermal energy extraction.
© Shannon Gilley
macarthur_100mchange_video_link

Inexhaustible resource of clean, renewable Geothermal Energy.
© ETH Zurich

By 2050, geothermal energy can cover 25% of Switzerland’s heating needs in a CO2-neutral way.
© Daniel Stegmann

Grimsel rock laboratory, safer drilling methods.
© 3sat nano

GEG Events

15.04.2024    10:45-12:30 (local time)
Integrated reservoir and production system modeling of geothermal energy extraction at the Aquistore CCS site in Canada

Kevin Peter Hau (invited talk)
European Geosciences Union 2024, Vienna, Austria


NEXT EVENT
30.04.2024    13:30-14:30
TANGO development

Morteza Esmaeil Pour (GEG group presentation)
GEG Meetings, ETH Zurich


21.05.2024    13:30-14:30
Demonstration of Reaktoro for geochemical modeling using Jupyter Notebooks."

Allan Leal (GEG group presentation)
GEG Meetings, ETH Zurich


28.05.2024    13:30-14:30
Update of working progress

Lily Suherlina (GEG group presentation)
GEG Meetings, ETH Zurich



Newest GEG Papers

Refereed journal papers accepted the last 6 months

Underlined names are links to current or past GEG members


The Dynamics of Per- and Polyfluoroalkyl Substances (PFAS) at Interfaces in Porous Media: A Computational Roadmap from Nanoscale Molecular Dynamics Simulation to Macroscale Modeling
Sookhak Lari, K., G. Davis, A. Kumar, J. Rayner, X.-Z. Kong, and M.O. Saar, ACS Omega, 2024. https://doi.org/10.1021/acsomega.3c09201 [Download] [View Abstract]Managing and remediating perfluoroalkyl and polyfluoroalkyl substance (PFAS) contaminated sites remains challenging. The major reasons are the complexity of geological media, partly unknown dynamics of the PFAS in different phases and at fluid− fluid and fluid−solid interfaces, and the presence of cocontaminants such as nonaqueous phase liquids (NAPLs). Critical knowledge gaps exist in understanding the behavior and fate of PFAS in vadose and saturated zones and in other porous media such as concrete and asphalt. The complexity of PFAS−surface interactions warrants the use of advanced characterization and computational tools to understand and quantify nanoscale behavior of the molecules. This can then be upscaled to the microscale to develop a constitutive relationship, in particular to distinguish between surface and bulk diffusion. The dominance of surface diffusion compared to bulk diffusion results in the solutocapillary Marangoni effect, which has not been considered while investigating the fate of PFAS. Without a deep understanding of these phenomena, derivation of constitutive relationships is challenging. The current Darcy scale mass-transfer models use constitutive relationships derived from either experiments or field measurements, which makes their applicability potentially limited. Here we review current efforts and propose a roadmap for developing Darcy scale transport equations for PFAS. We find that this needs to be based on systematic upscaling of both experimental and computational studies from nano- to microscales. We highlight recent efforts to undertake molecular dynamics simulations on problems with similar levels of complexity and explore the feasibility of conducting nanoscale simulations on PFAS dynamics at the interface of fluid pairs. (Paper accepted 2023-12-21)
Impact of Temperature on the Performance of Plasma-Pulse Geo-Drilling (PPGD)
Ezzat, M., J. Beorner, B. Kammermann, E. Rossi, B.M. Adams, V. Wittig, J. Biela, H-O. Schiegg, D. Vogler, and M.O. Saar, Rock Mechanics and Rock Engineering, 2024. https://doi.org/10.1007/s00603-023-03736-y [Download] [View Abstract]Advanced Geothermal Systems (AGS) may in principle be able to satisfy the global energy demand using standard continental-crust geothermal temperature gradients of 25-35◦C/km. However, conventional mechanical rotary drilling is still too expensive to cost-competitively provide the required borehole depths and lengths for AGS. This highlights the need for a new, cheaper drilling technology, such as Plasma-Pulse Geo-Drilling (PPGD), to improve the economic feasibility of AGS. PPGD is a rather new drilling method and is based on nanoseconds-long, high-voltage pulses to fracture the rock without mechanical abrasion. The absence of mechanical abrasion prolongs the bit lifetime, thereby increasing the penetration rate. Laboratory experiments under ambient-air conditions and comparative analyses (which assume drilling at a depth between 3.5 km and 4.5 km) have shown that PPGD may reduce drilling costs by approximately 17-23%, compared to the costs of mechanical drilling, while further research and development are expected to reduce PPGD costs further. However, the performance of the PPGD process under deep wellbore conditions, i.e., at elevated temperatures as well as elevated lithostatic and hydrostatic pressures, has yet to be systematically tested. In this paper, we introduce a standard experiment parameter to examine the impact of deep wellbore conditions on drilling performance, namely the productivity (the excavated rock volume per pulse) and the specific energy, the latter being the amount of energy required to drill a unit volume of rock. We employ these parameters to investigate the effect of temperature on PPGD performance, with temperatures increasing up to 80◦C, corresponding to a drilling depth of up to approximately 3 km. (Paper accepted 2023-12-17)