Hydrogeological properties of hyper-saline geothermal brine and application of inhibiting siliceous scale via pH modification

• Scaling is one of the important problems in geothermal system.
• Scaling reduces the efficiency of the plant and causes economical loss.
• The scales formed in the Tuzla geothermal system were divided into two groups according to location.
• Downhole the scales were composed mainly of PbS and CaCO3.
• The surface pipeline contained saponite like amorphous structure.

Scaling is a major obstacle in harnessing of geothermal energy from the geothermal resources. This paper presents a case study for inhibition of metal silicate scaling using formic acid, harvesting more energy in particular case of Tuzla Geothermal Field (TGF), located on Biga Peninsula, in the northwestern of Turkey. TGF is 5 km far from Aegean Sea and 80 km south of Çanakkale. Geothermal fluid of TGF has high salinity (EC > 91 mS/cm) and medium temperature (reservoir temperature is 173 °C). The acidification of high-salinity brine to mitigate silicate scaling is examined. Results of the study showed that a compromise between scaling and corrosion is achieved by reducing pH of brine to <6 using 55 ppm formic acid.