The precipitation of minerals (scales) from produced fluids in geothermal plants is a known problem from oil and gas industries. To avoid precipitation on plant equipment (e.g. pipes, pumps, heat exchanger) and in injection wells respectively, inhibitors can be applied. These additives would react with the components of the solution responsible for the mineral precipitation.

The goal of the subproject conducted by the International Centre for Geothermal Research (IGC) at the German Research Centre for Geosciences is the determination of the stability and efficiency of the inhibitors at reservoir-like conditions. Additionally, the degradation pattern of the inhibitors in natural and synthetic fluids will be characterized.

The experiments on inhibitor properties in natural and synthetic fluids subjected to pressure and temperature will be conducted in specific high pressure reactors. In addition, the influence of different parameters such as pH and salinity to the degradation pattern of the inhibitor in synthetic fluids will be examined within the reactors. The reactors provide excellent possibilities for a continuous monitoring of chemical processes with in situ measurements of conductivity, redox potential as well as speed of sound. Furthermore, molecular binding and complexed substances of the inhibitors can be (in situ) investigated at high pressure and high temperature conditions by Fourier transform infrared (FTIR) spectroscopy.

The precipitated solid phases (scales) are characterized for their mineral content, by X-ray diffraction, and for their characterization and changes in molecular binding by FTIR spectroscopy. The description of crystals such as morphology and sizes of the scales can be examined by scanning electron microscope (SEM) and optical microscope.