Acrylamide‐Sodium Vinyl Sulfonate Copolymers as Scale Inhibitor: Influence of Composition, Molar Mass and Chemical Modification

ABSTRACT The injection of seawater into petroleum reservoirs is employed to increase production. However, since seawater is rich in sulfate ions and connate water is rich in calcium, strontium, and barium ions, this mixture leads to the formation of insoluble salts, which form deposits that can block pipelines and damage pumps and valves. Chemical additives are used to prevent the formation of these deposits. However, there are still conditions in which commercial additives are not effective, justifying the investigation of different structures with the potential to inhibit inorganic fouling. Thus, we evaluate the influence of the composition, molar mass, and chemical modification (by insertion of phosphonic groups) of an acrylamide and sodium vinyl sulfonate (AC:VS) copolymer on the efficiency of inhibiting sulfate scaling. The materials are characterized in terms of structure, molar mass, and thermal stability. The following AC:VS compositions are obtained: 88:12, 75:25, 57:43, and 39:61. All copolymers are thermally stable and compatible with calcium ions. In general, AC:VS copolymers have similar performance (dynamic scale looping) to the commercial reference, and their chemical modification improves their performances. Morphological analyses indicate that the copolymers with high efficiency modify the crystal surface, forming asymmetric crystals that are less adherent.