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

Abstract

The CaCO 3 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, 1 H-NMR, and GPC. The static scale inhibition experiment was conducted to study the influence of factors such as the dosage, monomer ratio, temperature, pH, Ca 2+ concentration, and HCO − 3 concentration on the scale inhibition performance of CaCO 3 . 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 Ca 2+ 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 CaCO 3 crystal by adsorption, dispersion, and chelation. The effect leads to changes in the morphology of CaCO 3 crystals, the size of which drops from 20-30 μm to 2-5 μm. The P(MA-AA-AMPS) can transform CaCO 3 from stable calcite crystals to unstable aragonite and vaterite. Finally, the formation of CaCO 3 scale is well inhibited.

Formation and Inhibition of Calcium Carbonate Crystals under Cathodic Polarization Conditions

“…The value of η s changed little when the PBTCA concentration continued to increase. Many scale inhibitors, including PBTCA can adsorb and chelate with calcium ions, reducing the supersaturation of the scaling solution and thus reducing the nucleation rate of CaCO 3 crystals, therefore inhibiting the deposition of CaCO 3 [23,24]. During the nucleation of the crystal, the scale inhibitor might also form slightly soluble calcium salts with calcium ions and encapsulate the surface of solid impurities which act as a crystal center, thereby preventing the nucleation and growth of CaCO 3 crystals on the solid impurities [25].…”

Synthesis, characterization and properties of a novel environmentally friendly ternary hydrophilic copolymer

“…6,10,26 In addition, the molecular weight of the synthesized scale inhibitor is mostly in four orders of magnitude compared with the molecular weight of the monomer, which not only indicates the complete polymerization of the monomer but also can make use of the synergistic effect of various functional groups to make the copolymer have excellent scale inhibition properties. 6,15…”

“…6,10,26 In addition, the molecular weight of the synthesized scale inhibitor is mostly in four orders of magnitude compared with the molecular weight of the monomer, which not only indicates the complete polymerization of the monomer but also can make use of the synergistic effect of various functional groups to make the copolymer have excellent scale inhibition properties. 6,15 3.4 Optimum design of synthetic conditions of tercopolymer 3.4.1 Effects of dosage and monomer ratio. The copolymer structure consists of hydrophobic and hydrophilic groups, with carboxyl and sulfonic acid groups as hydrophilic groups and benzene rings and carbon chains as hydrophobic groups.…”

“…The sulfonic acid group is a strong hydrophilic group, which not only increases the water solubility but also prevents the formation of calcium gel. 12,15 The amide group increases the solubility of the inhibitor by forming hydrogen bonds and reacts with calcium ions to enhance the adsorption ability of the inhibitor on the particle surface. 16 In addition, the heteroatoms in these groups of polymeric scale inhibitors, such as O, N, and S, have high electron density and can form multiple bonds, which can provide multiple adsorption sites and promote the ability to chelate metal cations to make them adsorbed on the crystal surface of the sediment.…”

Synthesis and performance evaluation of carboxyl‐rich low phosphorus copolymer scale inhibitor

“…In the petroleum industry, the scaling problem under the reuse of recycled water is one of the main problems that restrict production, among which CaCO 3 CaSO 4 is the most common. 1,2 Especially with the in-depth development of oil fields, the formation energy cannot meet the normal production of the oil field, and water injection is needed to supplement the formation energy to improve the recovery rate. However, once the reinjection water is not compatible with the formation water or different reinjection water, serious fouling problems will occur, resulting in poor formation permeability, increased injection pressure, and blockage from the surface pipe network to the wellbore.…”