Synthesis and evaluation of an environment‐friendly terpolymer CaCO3 scale inhibitor for oilfield produced water with better salt and temperature resistance

Abstract

ABSTRACTThe CaCO3 deposits exist widely in the petroleum industry, causing severe damage to the equipment and production. In this article, a novel environment‐friendly terpolymer scale inhibitor Poly (maleic anhydride ‐ acrylic acid ‐2‐ acrylamide ‐2‐ methyl propanesulfonic acid) (P(MA‐AA‐AMPS))‐containing carboxylic acid group, sulfonic acid group, and amide group was synthesized. The structure and molecular weight were characterized by FTIR, 1H‐NMR, and GPC. The static scale inhibition experiment was conducted to study the influence of factors such as the dosage, monomer ratio, temperature, pH, Ca2+ concentration, and concentration on the scale inhibition performance of CaCO3. The results show that when the monomer ratio is 2.0:1.0:0.5 and the dosage is 20 mg L−1, the maximum scale inhibition efficiency is 95.52%. Even when Ca2+ concentration exceeds 1200 mg L−1 and temperature reaches 90 °C, the scale inhibition efficiency is still larger than 80%. The results of SEM and XRD show that P(MA‐AA‐AMPS) interferes with the growth of CaCO3 crystal by adsorption, dispersion, and chelation. The effect leads to changes in the morphology of CaCO3 crystals, the size of which drops from 20–30 μm to 2–5 μm. The P(MA‐AA‐AMPS) can transform CaCO3 from stable calcite crystals to unstable aragonite and vaterite. Finally, the formation of CaCO3 scale is well inhibited. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48460.