Synthesis of a New Type of 2-Phosphonobutane-1,2,4-tricarboxylic-Acid-Modified Terpolymer Scale Inhibitor and Its Application in the Oil Field

A hydrophilic terpolymer scale inhibitor (AA–APES–HPAY) was prepared by free radical polymerization with acrylic acid (AA), hydroxypropyl acrylate modified by 2-phosphonobutane-1,2,4-tricarboxylic acid (HPAY), and allyl polyethoxyammonium sulfonate (APES) as monomers in aqueous solution. The structure of the copolymer was characterized by Fourier transform infrared spectroscopy and hydrogen nuclear magnetic resonance spectroscopy. The effectiveness of AA–APES–HPAY depends upon the monomer mass ratio, temperature, and amount of initiator. According to the oil field scale prevention performance test method, the inhibition efficiency of CaCO3 reached 89.2% at a level of 21 mg/L and the CaSO4 inhibition was 92.4% at the low level of 3 mg/L. The surface morphology and crystal form of the scale and the principle of scale inhibition were analyzed by scanning electron microscopy and X-ray powder diffraction. The scale inhibition mechanism is proposed and analyzed in detail.