Evaluation of polyelectrolytic complexes based on poly(epichlorohydrin-co-dimethylamine) and poly (4-styrene-sulfonic acid-co-maleic acid) in the delivery of polyphosphates for the control of CaCO3 scale in oil wells

• Published in: Journal of molecular liquids 2021-10, Vol.339, p.116757, Article 116757
• Main Authors: de Morais, Stéphanie C., Bezerra, Breno G.P., Castro, Bruno B., Balaban, Rosangela de C.
• Format: Article
• Language: English
• Subjects: Calcium carbonate; Polyelectrolyte complex; Scale inhibition; Scale inhibitor squeeze process
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2021.116757

[Display omitted] •A new PEC based on EPI-DMA, PSSMA and SHMP has been successfully developed.•PEC provides excellent CaCO3 scale inhibition efficiency at MIC of 2.0 mg L-1.•The PEC formulation showed a reduction in stability with the increase of temperature.•The use of PEC improved the durability of the CaCO3 scale treatment by 100%. Polyelectrolytes complexes (PEC) based on poly(epichlorohydrin-co-dimethylamine) (EPI-DMA) and poly(4-styrene-sulfonic acid-co-maleic acid) (PSSMA) for polyphosphates encapsulation were prepared for the first time. The sodium hexametaphosphate (SHMP) was used as a model polyphosphate in this work. A factorial design 23 was applied to optimize PEC formulations. The resultant PEC suspensions were characterized by dynamic light scattering (DLS), zeta potential and encapsulation efficiency (EE) of SHMP. The best results were found by formulation using 1% (w/w) of EPI-DMA, 0.1% (w/w) of PSSMA and addition of SHMP before PSSMA. This optimized formulation was applied in real oil well conditions and showed good stability at 25 °C and reduced stability with increasing temperature. PEC showed excellent inhibition efficiency against calcium carbonate scale with minimum inhibitory concentration (MIC) of 2.0 mg L-1 at 100 °C and 1000 psi. PEC suspension also showed exceptional performance on assessment to sandstone, improving not only the adsorption of the material on the rock grains but also the durability of the scale inhibitor squeeze process by 100%.