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). (C) 2014 Elsevier Ltd. All rights reserved.