Seismicity induced in geo-reservoirs can be a valuable observation to image fractured reservoirs, to characterize hydrological properties, or to mitigate seismic hazard. However, this requires accurate location of the seismicity, which is nowadays an important seismological task in reservoir engineering. The earthquake location (determination of the hypocentres) depends on the model used to represent the medium in which the seismic waves propagate and on the seismic monitoring network. In this work, location uncertainties and location inaccuracies are modeled to investigate the impact of several parameters on the determination of the hypocentres: the picking uncertainty, the numerical precision of picked arrival times, a velocity perturbation and the seismic network configuration. The method is applied to the geothermal site of Soultz-sous-Forêts, which is located in the Upper Rhine Graben (France) and which was subject to detailed scientific investigations. We focus on a massive water injection performed in the year 2000 to enhance the productivity of the well GPK2 in the granitic basement, at approximately 5 km depth, and which induced more than 7000 earthquakes recorded by down-hole and surface seismic networks. We compare the location errors obtained from the joint or the separate use of the down-hole and surface networks. Besides the quantification of location uncertainties caused by picking uncertainties, the impact of the numerical precision of the picked arrival times as provided in a reference catalogue is investigated. The velocity model is also modified to mimic possible effects of a massive water injection and to evaluate its impact on earthquake hypocentres. It is shown that the use of the down-hole network in addition to the surface network provides smaller location uncertainties but can also lead to larger inaccuracies. Hence, location uncertainties would not be well representative of the location errors and interpretation of the seismicity distribution possibly biased. This result also emphasizes that it is still necessary to properly describe the seismic propagation medium even though the addition of down-hole sensors increases the coverage of a surface network.
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Bachura, M., & Fischer, T. (2016). Detailed velocity ratio mapping during the aftershock sequence as a tool to monitor the fluid activity within the fault plane. Earth and Planetary Science Letters, 453, 215–222. https://doi.org/10.1016/j.epsl.2016.08.017.
Baillieux, P., Schill, E., Edel, J.-B., & Mauri, G. (2013). Localization of temperature anomalies in the Upper Rhine Graben: Insights from geophysics and neotectonic activity. International Geology Review, 55(14), 1744–1762. https://doi.org/10.1080/00206814.2013.794914.
Bardainne, T., & Gaucher, E. (2010). Constrained tomography of realistic velocity models in microseismic monitoring using calibration shots. Geophysical Prospecting, 58(5), 739–753. https://doi.org/10.1111/j.1365-2478.2010.00912.x.
Baria, R., Baumgärtner, J., Gérard, A., & Garnish, J. (2000). The European HDR programme: main targets and results of the deepening of the well GPK2 to 5000 m. In Proceedings World Geothermal Congress 2000, Kyushu-Tohoku, Japan, 28 May–10 June 2000, pp. 3643–3652.
Calò, M., Dorbath, C., Cornet, F. H., & Cuenot, N. (2011). Large-scale aseismic motion identified through 4-D P-wave tomography. Geophysical Journal International, 186(3), 1295–1314. https://doi.org/10.1111/j.1365-246X.2011.05108.x.
Charléty, J., Cuenot, N., Dorbath, C., & Dorbath, L. (2006). Tomographic study of the seismic velocity at the Soultz-sous-Forêts EGS/HDR site. Geothermics, 35(5–6), 532–543. https://doi.org/10.1016/j.geothermics.2006.10.002.
Charléty, J., Cuenot, N., Dorbath, L., Dorbath, C., Haessler, H., & Frogneux, M. (2007). Large earthquakes during hydraulic stimulations at the geothermal site of Soultz-sous-Forêts. International Journal of Rock Mechanics and Mining Sciences, 44(8), 1091–1105. https://doi.org/10.1016/j.ijrmms.2007.06.003.
Cornet, F. H., Bérard, T., & Bourouis, S. (2007). How close to failure is a granite rock mass at a 5 km depth? International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, 44(1), 47–66. https://doi.org/10.1016/j.ijrmms.2006.04.008.
Cuenot, N. (2009). Réponse du granite fracturé de Soultz-sous-Forêts à des injections massives de fluide: Analyse de la microsismicité induite et du régime de contraintes, Ph.D. Thesis, Université de Strasbourg, Strasbourg, France.
Cuenot, N., Dorbath, C., & Dorbath, L. (2008). Analysis of the microseismicity induced by fluid injections at the EGS site of Soultz-sous-Forêts (Alsace, France): Implications for the characterization of the geothermal reservoir properties. Pure and Applied Geophysics, 165(5), 797–828. https://doi.org/10.1007/s00024-008-0335-7.
Dahm, T., & Fischer, T. (2014). Velocity ratio variations in the source region of earthquake swarms in NW Bohemia obtained from arrival time double-differences. Geophysical Journal International, 196(2), 957–970. https://doi.org/10.1093/gji/ggt410.
Dorbath, L., Cuenot, N., Genter, A., & Frogneux, M. (2009). Seismic response of the fractured and faulted granite of Soultz-sous-Forêts (France) to 5 km deep massive water injections. Geophysical Journal International, 177(2), 653–675. https://doi.org/10.1111/j.1365-246X.2009.04030.x.
Dyer, B. C. (2001). Soultz GPK2 stimulation June/July 2000: Seismic monitoring report. Socomine: Semore Seismic Report.
Dyer, B. C. (2005). Soultz GPK4 stimulation September 2004 to April 2005: Seismic monitoring report, Semore Seismic Report BP38, EEIG Heat Mining, F-67250 Kutzenhausen.
Dyer, B. C., Baria, R., & Michelet, S. (2003). Soultz GPK3 stimulation and GPK3-GPK2 circulation May to July 2003: Seismic monitoring report, Semore Seismic Report, 69 pp., EEIG Heat Mining.
Gaucher, E. (1998). Comportement hydromécanique d’un massif fracturé: Apport de la microsismicité induite. Application au site géothermique de Soultz-sous-Forêts (Hydro-mechanical behaviour of a fractured rock mass: Induced microseismicity contribution. Application to the Soultz-sous-Forêts geothermal site), Ph.D. Thesis, Université Paris 7, Paris, France.
Gaucher, E., Kinnaert, X., Achauer, U., & Kohl, T. (2016). Propagation of velocity model errors in earthquake absolute locations: Application to the Rittershoffen (France) Geothermal Field, in 41st workshop on geothermal reservoir engineering.
Genter, A., Evans, K., Cuenot, N., Fritsch, D., & Sanjuan, B. (2010). Contribution of the exploration of deep crystalline fractured reservoir of Soultz to the knowledge of enhanced geothermal systems (EGS). Comptes Rendus Geoscience, 342(7–8), 502–516. https://doi.org/10.1016/j.crte.2010.01.006.
Gérard, A., & Kappelmeyer, O. (1987). The Soultz-sous-Forets project. Geothermics, 16(4), 393–399. https://doi.org/10.1016/0375-6505(87)90018-6.
Gritto, R., & Jarpe, S. P. (2014). Temporal variations of Vp/Vs-ratio at The Geysers geothermal field, USA. Geothermics, 52, 112–119. https://doi.org/10.1016/j.geothermics.2014.01.012.
Held, S., Genter, A., Kohl, T., Kölbel, T., Sausse, J., & Schoenball, M. (2014). Economic evaluation of geothermal reservoir performance through modeling the complexity of the operating EGS in Soultz-sous-Forêts. Geothermics, 51, 270–280. https://doi.org/10.1016/j.geothermics.2014.01.016.
Kinnaert, X., Gaucher, E., Achauer, U., & Kohl, T. (2016). Modelling earthquake location errors at a reservoir scale: A case study in the Upper Rhine Graben. Geophysical Journal International, 206, 861–879. https://doi.org/10.1093/gji/ggw184.
Kohl, T., & Mégel, T. (2007). Predictive modeling of reservoir response to hydraulic stimulations at the European EGS site Soultz-sous-Forêts. International Journal of Rock Mechanics and Mining Sciences, 44(8), 1118–1131. https://doi.org/10.1016/j.ijrmms.2007.07.022.
Kwiatek, G., Bohnhoff, M., Dresen, G., Schulze, A., Schulte, T., Zimmermann, G., et al. (2010). Microseismicity induced during fluid-injection: A case study from the geothermal site at Groß Schönebeck, North German Basin. Acta Geophysica, 58(6), 995–1020. https://doi.org/10.2478/s11600-010-0032-7.
Lomax, A. (2011). The NonLinLoc home page. http://alomax.free.fr/nlloc/.
Lomax, A., Michelini, A., & Curtis, A. (2009). Earthquake location, direct, global-search methods. In R. A. Meyers (Ed.), Encyclopedia of complexity and systems science (pp. 2449–2473). New York: Springer.
Megies, T., & Wassermann, J. (2014). Microseismicity observed at a non-pressure-stimulated geothermal power plant. Geothermics, 52, 36–49. https://doi.org/10.1016/j.geothermics.2014.01.002.
Place, J., Diraison, M., Naville, C., Géraud, Y., Schaming, M., & Dezayes, C. (2010). Decoupling of deformation in the Upper Rhine Graben sediments. Seismic reflection and diffraction on 3-component Vertical Seismic Profiling (Soultz-sous-Forêts area). Comptes Rendus Geoscience, 342(7–8), 575–586. https://doi.org/10.1016/j.crte.2010.01.001.
Podvin, P., & Lecomte, I. (1991). Finite difference computation of travel times in very contrasted velocity models: A massively parallel approach and its associated tools. Geophysical Journal International, 105(1), 271–284. https://doi.org/10.1111/j.1365-246X.1991.tb03461.x.
Sausse, J., Dezayes, C., Dorbath, L., Genter, A., & Place, J. (2010). 3D model of fracture zones at Soultz-sous-Forêts based on geological data, image logs, induced microseismicity and vertical seismic profiles. Comptes Rendus Geoscience, 342(7–8), 531–545. https://doi.org/10.1016/j.crte.2010.01.011.
Schill, E., Genter, A., Cuenot, N., & Kohl, T. (2017). Hydraulic performance history at the Soultz EGS reservoirs from stimulation and long-term circulation tests. Geothermics, 70(Supplement C), 110–124. https://doi.org/10.1016/j.geothermics.2017.06.003.
Schnaebele, R. (1948). Monographie géologique du champ pétrolifère de Pechelbronn. Strasbourg: Mémoire du Service de la Carte Géologique d’Alsace et de Lorraine.
Schoenball, M., Dorbath, L., Gaucher, E., Wellmann, J. F., & Kohl, T. (2014). Change of stress regime during geothermal reservoir stimulation. Geophysical Research Letters, 41(4), 1163–1170. https://doi.org/10.1002/2013gl058514.
Tarantola, A., & Valette, B. (1982). Inverse problems=quest for information. Journal of Geophysics, 50, 159–170.
Tukey, J. W. (1977). Exploratory data analysis. Behavioral Science (p. 503). Reading: Addison-Wesley.
Wenzel, F., & Brun, J.-P. (1991). A deep reflection seismic line across the Northern Rhine Graben. Earth and Planetary Science Letters, 104(2–4), 140–150. https://doi.org/10.1016/0012-821X(91)90200-2.
Wittlinger, G., Herquel, G., & Nakache, T. (1993). Earthquake location in strongly heterogeneous media. Geophysical Journal International, 115(3), 759–777. https://doi.org/10.1111/j.1365-246X.1993.tb01491.x.
This work was conducted in the framework of the excellence laboratory “Labex G-EAU-THERMIE PROFONDE” (University of Strasbourg). It was funded by the French National Research Agency, as part of the French “Investments for the future” program, by the Energie Baden-Württemberg AG (EnBW), the French institution CNRS, and by the French-German University (DFH-UFA). We wish to thank the EEIG “Heat Mining” for sharing data. We are grateful to N. Cuenot and A. Genter for fruitful discussions on the Soultz experiments and raw seismic datasets. We also thank L. and C. Dorbath for providing the seismic data catalogues and sharing their knowledge on the seismic datasets. We are very grateful to T. Plenefisch and another anonymous reviewer for their advices and remarks, which greatly improved the manuscript.
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Kinnaert, X., Gaucher, E., Kohl, T. et al. Contribution of the Surface and Down-Hole Seismic Networks to the Location of Earthquakes at the Soultz-sous-Forêts Geothermal Site (France). Pure Appl. Geophys. 175, 757–772 (2018). https://doi.org/10.1007/s00024-017-1753-1
- Location inaccuracy
- location uncertainty
- network design
- induced seismicity