Chemical Control of Silica Scaling in Geothermal Systems

A common method for protecting carbon steel against mineral scaling in geothermal systems is the continuous injection of scale inhibitors into the process fluid. These inhibitors can function through a number of differing mechanisms in order to reduce the nucleation and/or growth of mineral scales. Towards higher temperatures, the functionality of many scaling inhibitors is lost. Although the development of thermodynamically stable inhibitors is possible, this typically comes at a price of increased toxicity and reduced bio-degradability. Due to the ever-tightening legislation associated with chemistries used for industrial processes, the synthesis of new inhibitory molecules proves extremely challenging. Recent research has resulted in the synthesis of a new class of chemistries which have shown potential for control of silica deposition, though the mechanism of inhibition remains unclear. The project will explore new methodologies for the evaluation of such inhibitory molecules using bespoke high pressure and high temperature systems, with the intention of improving the understanding of the scaling inhibition mechanisms. This joint PhD project with Schlumberger Cambridge Research Centre will focus on the evaluation and optimisation of newly developed geothermal silica scaling inhibitors. These new chemistries are designed to mitigate internal silica scaling deposition onto carbon steel in demanding, high temperature aqueous CO2-containing environments, analogous to those encountered in geothermal systems.