Preparation of carboxy sulfonic acid-containing copolymer scale inhibitors and their scale inhibition effect on CaCO3

Free radical polymerization was selected to obtain a promising copolymer scale inhibitor IA-AM-SAS with good water solubility and temperature and salt resistance, which is suitable for the treatment of surface pipeline water in oil fields, using itaconic acid (IA), acrylamide (AM), and sodium acrylsulfonate (SAS) as the monomers. The structure of the synthesized copolymer was verified by Fourier transform infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy. Thermogravimetric results showed that the copolymer does not undergo significant thermal degradation at temperatures below 356°C, indicating that the copolymer has good thermal stability. The molecular weights of the polymers at different monomer ratios were measured using gel permeation chromatography and the relationship between the molecular weights and scale inhibition performance was discussed. The results showed that the scale inhibition effect was best when the monomer molar ratio n(IA): n(AM): n(SAS) was 0.5:2:1.5 and the number of average molecular weight of the prepared copolymer was 7712 g/mol, and the inhibition efficiency of CaCO₃ was 84.02% when IA-AM-SAS was at a concentration of 30 mg L⁻¹, and the inhibition rate was measured by the standard of static scale inhibition test in the oilfield measured. The range of conditions (PH, Ca²⁺ concentration, water temperature, and time) of the static scale inhibition test was then expanded using a one-way controlled variable experiment to explore the performance of IA-AM-SAS scale inhibitors under different water quality conditions. The scale inhibition mechanism was explored by scanning electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy. Briefly, the combination of multiple functional groups enables IA-AM-SAS to be applied in complex and challenging environments.