Solution chemistry of phosphino-polycarboxylic acid (PPCA) at high ionic strength and high temperature

[摘要] Phosphino-polycarboxylic acid (PPCA) and its modified types have the potential to be used as multifunctional inhibitors and they have advantages over unifunctional inhibitors in performance, thermal stability, dispersancy and environmental acceptability. The thermodynamic properties of PPCA have therefore been investigated by means of experiments at high ionic strength and high temperature. These properties include the equilibrium constant of proton association-dissociation $m (pKsb{H}),$ the equilibrium constant of Ca-PPCA complexation $m (pKsb{M})$ and the equilibrium constant of CaPPCA precipitation-dissolution $m (pKsb{sp}).$ In this thesis, relationships between these constants and temperature, ionic strength, pH, and concentration are developed. Relevant to these thermodynamics, models on multi-equilibria of polyelectrolytes are discussed and a method of defining the solubility product of CaPPCA is developed. An improved method to measure PPCA in brines was also developed. Finally, application of these results to scale control in gas and oil production is discussed with specific field results.

[发布机构] Rice University

[效力级别] chemistry