Geochemical and reactive transport modeling of the injection of cooled Triassic brines into the Dogger aquifer (Paris basin, France)

Abstract : As another option for exploitation of the low-enthalpy geothermal resources of the Paris basin (France), currently limited to the carbonate Dogger aquifer, brine could be extracted from deeper Triassic sandstone reservoirs and re-injected into the Dogger aquifer, which has higher injectivity. The objective of the geochemical modeling work presented here is to identify the physical-chemical processes that are likely to be induced by the re-injection of the cooled Triassic brines into the Dogger aquifer and to predict their possible consequences on the Dogger porosity. The results suggest that this re-injection process may induce precipitation/dissolution reactions. However, the impact on porosity should be limited in magnitude (a few percent) and in extent (tens of meters around the well).