Redissolution studies in bulk and in coreflood for PPCA scales inhibitor

Phosphino-polycarboxylate acid (PPCA) was chosen as a model inhibitor for scales inhibition and employed in precipitation and redissolution studies carried out in bulk and in coreflood media. xes, obtained starting from different inhibitor–calcium formulations and in different conditions, were investigated and the solubility of the precipitates with different molecular weight was studied in brines with different calcium content. The thermodynamic and kinetics of inhibitor redissolution was considered in terms of solubility of precipitated inhibitor and its rate of dissolution. The molecular weight distributions of the precipitated and of the redissolved fractions were studied to assess the hypothesis of inhibitor fractionation during inhibitor precipitation and back-production. The effect of molecular weight of precipitated inhibitor on inhibitor return was further investigated in coreflood experiments carried out under field reservoir conditions employing two different inhibitor–calcium formulations. The role of brineʹs characteristics and flow rate on the solubility of precipitate inhibitor and its rate of redissolution was clearly evidenced. mplications of these results for the optimization of the precipitation squeeze technology for field applications are also discussed.