| Title | Scale Inhibition at the Soultz-sous-Forêts (France) EGS Site: Laboratory and On-Site Studies |
|---|---|
| Authors | Julia SCHEIBER, Andrea SEIBT, Johannes BIRNER, Albert GENTER, Nicolas CUENOT, Wilfried MOECKES |
| Year | 2015 |
| Conference | World Geothermal Congress |
| Keywords | barite scaling, phosphonic acid, NORM, inhibitor selection, inhibitor injection |
| Abstract | Scale formation in the surface and subsurface installations of the Soultz geothermal power plant affect negatively operational performance of the geothermal cycle. For reasons of safety at work and long term power plant operation, the formation of barite needs to be inhibited continuously. Therefore, several inhibitor products, based on phosphonic acids, were tested in laboratory experiments. This study included laboratory tests for calcium tolerance, effectiveness and dose rate adjustment by tube blocking tests with artificial and original Soultz brine. Based on the performance during the tests, one product showed the best results for barite inhibition at the Soultz site and was consequently selected for additional laboratory tests which investigated long-term efficiency, thermal stability and reservoir rock/inhibitor interactions. The inhibitor suppressed successfully barite formation for 24 h at 90°C in contact with reservoir rock material. Small scale laboratory tests were found to be simple but powerful tools for inhibitor selection, efficiency tests and dose rate adjustment before inhibitor on-site application. Geothermal fluids trapped within deep-seated fractured crystalline rocks from the Upper Rhine Valley must be carefully investigated in order to minimize scaling (sulfate, sulfide) and seriously limit the natural radioactivity associated with. At the Soultz site an inhibitor injection system was designed, installed and tested for continuously inhibitor injection. The on-site efficiency test showed very promising results during the short-time test for barite scale mitigation. |