The Inhibitory Effect of Low Phosphorus and Low Molecular Weight Terpolymer Scale Inhibitor on Calcium Scale in Oilfields

Abstract

ABSTRACTThe study utilized itaconic acid (IA), N‐hydroxyethyl acrylamide (HEAA), and sodium hypophosphite (SHP) as starting materials for a free radical polymerization process. This process resulted in creating a new type of low‐phosphorus terpolymer scale inhibitor called P(IA‐HEAA‐SHP). Its primary application was as an effective scale inhibitor to block CaCO3 and CaSO4. FTIR, 1H‐NMR, and 13C‐NMR were used to characterize the synthesized copolymer structures, and it was confirmed that the synthesized products had the desired structures. The synthesis conditions have been optimized using the static scale inhibition approach, which involved adjusting the monomer ratio, initiator dosage, and reaction time. This resulted in the synthesis of polymeric scale inhibitors with outstanding scale inhibition properties. Additionally, GPC was employed to examine the correlation of the molecular weight of the polymers with their scale inhibition properties at various reaction times. The results showed that when the monomer ratio n(IA):n(HEAA) = 1.5:1, the SHP dosage mass fraction was 15%, the ammonium persulfate initiator dosage was 10%, the reaction temperature was 90°C, and the reaction time was 4 h. At a measured dose of 30 mg L−1, the scale inhibition impact on CaCO3 is 86.63%, while the scale inhibition impact on CaSO4 is 96.83%. The thermal properties of the copolymers, the crystal structure, and the micro‐morphology of the scale samples were analyzed by TGA, XRD, and SEM, and the scale inhibition mechanism was discussed in conjunction with the zeta potential analysis.