Influence of Terpolymer Based on Amide, Carboxylic, and Sulfonic Groups on the Barium Sulfate Inhibition

In oilfield production systems, inhibitors are widely used to prevent mineral scale formation, and the most common and efficient way to apply inhibitors downhole is by using squeeze treatments. Polymers are an important class of compounds used as scale inhibitors; however, many specific conditions still require high performance additives. In this work, some ionic copolymers based on acrylamide, maleic acid, and vinyl sulfonic acid were synthesized, characterized by FT-IR, elemental analysis, and size exclusion chromatography, and tested regarding barium sulfate prevention. Static inhibition efficiency (IE) was carried out at 95 °C and pH 5.5 for two seawater/formation water volume ratios, i.e. 10/90 and 60/40. The minimum inhibitor concentration (MIC) for each polymer was also determined. Polymers containing −COOH, −CONH2, and −SO3H groups exhibited higher efficiency regarding barium sulfate inhibition than those containing only −COOH and −CONH2, for both saturation ratio. This behavior could be associated with a synergistic effect of carboxylic groups (−COOH), that can interact with barium ions, and acrylamide (−CONH2), which CO can interact with barium ions and NH2 with sulfate ions. It seems that the vinylsulfonic group contributed to chain flexibity more than to ion interaction.