Performance and mechanism study of IA-AMPS-HPA as an oilfield scale inhibitor: Experimental and molecular dynamics simulation

In this article, itaconic acid (IA), 2-acrylamide-2-methylpropanesulfonic acid (AMPS), and hydroxypropyl acrylate (HPA) served as the reaction's monomers, deionized water served as the reaction's solvent, and ammonium persulfate served as the reaction's initiator, with isopropanol serving as the chain transfer agent, a terpolymer scale inhibitor (IA-AMPS-HPA) was synthesized and used to prevent the growth of calcium carbonate (CaCO3) scale in an oilfield environment. On the effectiveness of scale inhibition, the influence of temperature, scale inhibitor concentration, pH, calcium ion concentration, and salt levels are examined. The results indicate that the scale inhibition rate progressively drops with growing temperature and gradually increases with rising scale inhibitor concentration. The scale inhibition rate reaches 97.67% when the temperature is 60 degrees C, and the scale inhibitor concentration is 60 mg/L. When the temperature is 80 degrees C and the concentration of scale inhibitor is 40 mg/L, the inhibitor's ability to block CaCO3 increases as the salt content rises. The scale inhibition rate is more than 85% when the pH is less than 9. Besides, the Ca2+ concentration is less than 300 mg/L, and the scale inhibition rate declines as the Ca2+ concentration rises, reaching a maximum value of 91.67% when the salt content is 33 g/L. With a rise in pH, the scale inhibition rate dropped. Employing a scanning electron microscope, the morphology of scale samples was described and analyzed. Molecular dynamics was utilized to simulate the interaction between IA-AMPS-HPA and the crystallization surface of CaCO3 at varying temperatures. The results show that the binding energy decreases as the system temperature rises and that the reaction between polymer molecules and CaCO3 crystals in the system can be observed by increasing the time step length and the water molecule concentration. The simulation results are with following the observed phenomena.

Automated summary

In this article, a terpolymer scale inhibitor (IA-AMPS-HPA) was synthesized and used to prevent the growth of calcium carbonate (CaCO3) scale in an oilfield environment. The effectiveness of scale inhibition was examined concerning temperature, scale inhibitor concentration, pH, calcium ion concentration, and salt levels. The results show that the scale inhibition rate decreases with increasing temperature and increases with rising scale inhibitor concentration. The scale inhibition rate is more than 85% when the pH is less than 9, and the Ca2+ concentration is less than 300 mg/L. Scanning electron microscopy was used to describe and analyze the morphology of scale samples. Molecular dynamics simulations revealed the interaction between IA-AMPS-HPA and the crystallization surface of CaCO3 at different temperatures.