| Abstract |
Deep seated fault systems play an important role in the utilization of deep geothermal energy, especially in non-volcanic enhanced geothermal systems with low natural permeability. In such settings the fluid migration and heat convection takes place through the connected fracture network that is often saturated with saline geothermal fluids, interacting with the primary and secondary mineral content of the host rock (Dissolution, precipitation, recrystallization). Intense pervasive alteration can for example be ob-served in granitic core samples from soultz-sous-forêts (E.G. Schleicher et al. 2006). Natural analogues from deep geothermal wells and mining sites in the black forest are therefore included in the study. The aim of this research is to comprehend the mineralogical alterations that occur, when the primary mineral assemblage is subjected to a synthetic geothermal fluid at temperatures above 200 °c. Important ques-tions are: (1) What are the relevant reaction steps, (2) How fast do the reactions take place, and (3) Can the observed reactions properly be described on the basis of an alteration model? Here, preliminary results from the experimental campaign are presented. |