Evaluating the Pre-Scaling Technique for Scale Inhibitor Testing: Advantages, Challenges, and Industry Insights

Abstract This study investigates the effectiveness of the pre-scaling technique for assessing scale inhibitor performance in dynamic tube blocking testing (DTB). The goal is to evaluate how pre-scaling conditions influence the minimum inhibitor concentration (MIC) of scale inhibitors in various brines and compare these results to standard testing on a clean coil. The research focuses on different salinity systems, testing with and without ferrous iron (Fe2+), and the challenges in achieving consistent results. In pre-scaling tests, inhibitor is tested on a coil with scale formed inside instead of on a clean coil, which is usually the standard. The pre-scaling method consistently resulted in higher MICs compared to clean coil tests in high total dissolved solid (TDS) and low TDS brines with and without Fe2+. In low TDS brine without Fe2+, the MIC under pre-scaling condition produces similar results to the MIC without pre-scaling. In medium and especially high TDS brines with Fe2+, the MIC under pre-scaling condition is significantly higher than the MIC without pre-scaling. To investigate this phenomenon, optimization plans were proposed and tested to improve the repeatability of pre-scaling tests, particularly in high-salinity and iron systems. However, MICs were more favorable in lower TDS brines without iron. High Fe2+ environments suggest that scale morphology, brine and iron composition significantly influence inhibitor performance under pre-scaling test conditions. The findings provide valuable insights into the application of pre-scaling in both low and high TDS brines, as well as with and without the presence of ferrous iron. The research highlights areas for further optimization in testing methodologies and inhibitor selection to improve pre-scale testing.