Development of a novel HT calcite scale inhibitor for geothermal applications

Abstract

Chemical treatment for preventing scale formation and deposition is now widely used in the geothermal industry. The high temperatures involved in the geothermal processes constitute one of the major challenges for most of the standard chemistries currently applied for scale inhibition. The chemical product may undergo a thermal degradation which cancel their scale inhibition effect and, in some cases, may generate additional scale due to by-product formation.
In this paper, the development of a novel, highly stable, chemical product is presented. Extensive lab work has been done with results and protocols described in detail. Compared to standard technologies, this new product has shown an exceptional thermal stability and excellent performance against calcite, which is one of the most common types of scale generally present in geothermal plants.
Following the good results obtained in the laboratory, an industrial trial was done in a 30MW plant in Turkey having high temperature reservoir (> 200°C) and severe silicate and calcite scaling issues. In the same plant, several different chemical
products were applied with very bad results. The new product was applied for two months, and the performance were assessed by checking the amount of scale formed on scale coupons and by monitoring the geothermal brine composition in
order to identify any variation in ions content that could be linked to scale precipitation.
At the end of the trial, the results confirmed the lab observation, by showing excellent performance in scale inhibition at such high temperature conditions.
Results presented in this paper represents a step forward in the development of new chemical product which can offer a more effective technology to geothermal operators aiming to improve their plants efficiency.