Café LabEx – Carole Glaas

Carole Glaas (CIFRE PhD)
Supervisory team: Prof. Jean-François Girard, Prof. Patricia Patrier, and Dr. Albert Genter 

The investigation of permeable hydrothermally altered and fractured zones and their distribution is a key issue for the understanding of fluid circulation in granitic rocks, on which relies the success of geothermal projects. Based on the use of short-wave infrared (SWIR) spectroscopy applied on rock cuttings coupled with geophysical logs interpretation, my PhD aims at answering how and where is distributed the fluid flow in the fracture zones (FZs) intersected by geothermal wells. First, the study of clay minerals from cuttings samples is made with the SWIR method which enables to quantify the illite resulting from hydrothermal alteration in the geothermal wells. This method has the advantage of beeing non-destructive and very rapid. Secondly, the electrical logs acquired in the geothermal wells will be inverted and modelled with an innovative software in order to decipher the fluid and the clay contribution in the electrical response. This PhD is based on the geological and geophysical dataset of the four geothermal wells of the Soultz-sous-Forêts geothermal plant, the two geothermal wells of the Rittershoffen geothermal plant and of the just-drilled geothermal well at the Illkirch site. After presenting the general framework of my PhD, some results of the hydrothermal alterations investigations and their preliminary correlation with geophysical logs will be detailed.