Evaluation of Scale Inhibitors in Marcellus High-Iron Waters

Abstract

Summary The Marcellus waters of Pennsylvania and West Virginia commonly contain elevated levels of calcium, barium, and iron. Theoretical analyses of these waters indicate a propensity toward the formation of calcium carbonate, barium sulfate, strontium sulfate, and iron-related scales. The high level of dissolved iron commonly present in the water adversely affects the ability of the scale inhibitor to inhibit calcium carbonate scale. In this study, the inhibition performance of two new chemicals and some commercial products was evaluated under static and dynamic test conditions using synthetic Marcellus waters at varying iron concentrations. It was shown that both new chemicals were able to control calcium carbonate scale effectively in the presence of dissolved iron up to 200 ppm, whereas the performance of polycarboxylic acid, amino tri(methylene phosphonic) acid, and carboxymethyl inulin dropped sharply even in the presence of small amounts of Fe2+ (5 ppm). The inclusion of iron-sequestering agents with these chemicals and the effect of iron upon calcium sulfate inhibition are also discussed in this paper.