TRIAS Project - Experiments to reinject geothermal brine into deep Triassic sandstones

After the favorable results obtained in exploiting the Dogger geothermal aquifer of the Paris Basin, attempts were made to exploit the warm waters of the Triassic sandstones. Its extent and temperature level made it a very promising target for developers. However, difficulties encountered at Acheres (Yvelines), Cergy (Val d'Oise) and Melleray - St Denis en Val (Loiret), particularly in geothermal brine reinjection tests after heat extraction, led the CCE, AFME and BRGM to fund a research program aimed at: - understanding the factors limiting injectivity in clay-sandstone aquifers, - defining perennial operating conditions for drilling doublets. The IMRG research team has undertaken experiments on geothermal fluid percolation through cores of artificial materials and natural sandstones of varying clay content. These experiments were carried out at the Melleray and Villefranche-sur-Cher sites in an experimental loop specially designed to be moved to construction sites. These investigations focused on: - the petrology and pore structure of the materials before and after percolation, - the monitoring of changes in the permeability of the materials, - the chemical characterization of the liquid and gaseous phases of the percolation fluid and the particles in suspension. These investigations enabled us to define a geothermal fluid treatment protocol prior to reinjection into the aquifer