Magnetotelluric (MT) is classically used in geophysical exploration for imaging electrical conductivity structures and is being developped as a monitoring technique. In geothermic during fluid injections and stimulation experiments, MT is used in addition to microseismic observations and can provide critical information to geothermal fluid flows because the electrical conductivity is related with temperature, porosity, water content and minerals of rocks. Some experiments have shown that such MT signals might be difficult to observe because they are at periods of 1–10 s, within the MT dead-band. We show actual data from Northern France then consider the sensitivity of MT monitoring by forward modelling. We use ModEM open source code to build a 3-dimensional model which includes topography and simple sedimentary conductive layers. Modelling allows us to simulate different changes that could be caused by brine and/or acid injection within fractures at depth and show subsequent MT monitoring parameters, particularly the phase tensor. From these models, it seems that MT monitoring in a sedimentary environment at 20 □.m could be sensitive to an increase of conductivity in a fault area at geothermal depths of 2–3 km if the size of the disturbed domain reaches about 10×0.3×2 km3.


Article metrics loading...

Loading full text...

Full text loading...


  1. Abdelfettah, Y., Sailhac, P., Schill, E., Larnier, H., Matthey, P.-D.:
    Continuous MT monitoring for small fluid injection at Rittershoffen geothermal project, northern Alsace, France, 23nd International Workshop on Electromagnetic Induction in the Earth, (2016), Chiang Mai, Thailand
    [Google Scholar]
  2. Abdelfettah, Y., Sailhac, P., Larnier, H., Matthey, P.-D., Schill, E.:
    Continuous MT monitoring of low volume fluid injection at Rittershoffen geothermal project, northern Alsace, France, Geothermics, (2017), under review
    [Google Scholar]
  3. Aizawa, K., Kanda, W., Ogawa, Y., Iguchi, M., Yokoo, A., Yakiwara, H. and Sugano, T.:
    Temporal changes in electrical resistivity at Sakurajima volcano from continuous magnetotelluric observations, Journal of Volcanology and Geothermal Research, 199, (2011), 165–175.
    [Google Scholar]
  4. Braun, N.:
    2D- und 3D-Magnetotellurik in Soultz-sous-Forêts, zur Lokalisation geothermisch genutzter Wässer, Diplomarbeit, Mainz univ., 107 p. (2009). (In German)
    [Google Scholar]
  5. Kelbert, A., Meqbel, N.M., Egbert, G.D. and Tandon, K.:
    ModEM: A modular system for inversion of electromagnetic geophysical data, Computers & Geosciences, 66, (2014), 40–53.
    [Google Scholar]
  6. Larnier, H., Sailhac, P., Chambodut, A.
    , New application of wavelet in data processing: reducing impedance bias, Earth, Planets and Space, (2016), 68:70.
    [Google Scholar]
  7. Mackie, R.L., Madden, T.R. and Wannamaker, P.E.:
    Three-dimensional magnetotelluric modeling using difference equations - Theory and coparisons to integral equation solutions. Geophysics, 58, (1993), 215–226. doi: 10.1190/1.1443407
    https://doi.org/10.1190/1.1443407 [Google Scholar]
  8. PeacockJ.R., Thiel, S., Ried, P. and Heinson, G.S.:
    Magnetotelluric monitoring of a fluid injection: Example from an enhanced geothermal system. Geophysical Research Letters, 39, (2012), L18403. doi: 10.1029/2012GL053080
    https://doi.org/10.1029/2012GL053080 [Google Scholar]
  9. PeacockJ.R., Thiel, S., Ried, P., Heinson, G.S. and Reid, P.:
    Time-lapse magnetotelluric monitoring of an enhanced geothermal system. Geophysics, 78, (2013), B121–130. doi: 10.1190/GEO2012‑0275.1
    https://doi.org/10.1190/GEO2012-0275.1 [Google Scholar]
  10. MacFarlane, J., Thiel, S., Pek, J., PeacockJ.R. and Heinson, G.S.:
    Characterisation of induced fracture networks within an enhanced geothermal system using anisotropic electromagnetic modelling, Journal of Volcanology and Geothermal Research, 288, (2014), 1–7.
    [Google Scholar]
  11. Sailhac, P, Tartrat, T., Larnier, H., Schill, E.:
    Prelimary results of MT monitoring following a stimulation experiment at Rittershoffen in Soultz geothermal area, France. 22nd International Workshop on Electromagnetic Induction in the Earth, (2014), Weimar, Germany, 24–30 August.
    [Google Scholar]
  12. ThielS, PeacockJR, HeinsonGS, RiedP, MesseillerM.:
    First results of monitoring fluid injection in EGS reservoirs using Magnetotellurics. Australian Geothermal Conference, (2011), Extended Abstract, pp 4.
    [Google Scholar]
  13. Warden, S., Sailhac, P., Garambois, S.
    , Microseismoelectric monitoring: a new technique to monitor hydraulic stimulation processes, EAGE Fall Meeting (2017), P0907.
    [Google Scholar]
  14. Wawrzyniak, P., Zlotnicki, J., Sailhac, P., and Marquis, G.:
    Resistivity variations associated with the large March 9, 1998 eruption at La Fournaise volcano inferred by continuous MT monitoring, Journal of Volcanology and Geothermal Research, (2017), under review.
    [Google Scholar]

Data & Media loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error