| Series of model, water-soluble copolymers of acrylamide (AM) with sodium 2-acrylamido-2-methylpropane sulfonate (NaAMPS), sodium 2-sulfoethyl methacrylate (NaSEM), sodium acrylate (NaA), N,N-dimethylacrylamide (DMAM), and N-(1,1-dimethyl-3-oxybutyl)acrylamide (DAAM) as well as AM-DAAM-NaAMPS terpolymers were synthesized and characterized in order to investigate structure-property-performance interrelationships.; Copolymer compositions were determined by elemental analyses, infrared spectroscopy and C-13 NMR. Monomer reactivity ratios were calculated using the Fineman-Ross, the Kelen-Tudos, and/or the Mayo-Lewis techniques at appropriate monomer conversions. Copolymer microstructure, including mean sequence length distribution, was calculated from reactivity ratios. Membrane osmometry and viscosity measurements were utilized to estimate molecular weight and size. The hydrodynamic volume of all synthesized model polymers in aqueous media was found to be a function of polymer concentration, salt concentration, temperature, shear rate and time. A linear relationship for polyelectrolyte models was observed between the zero-shear intrinsic viscosity, {lcub}(eta){rcub}(,o), and the reciprocal of the square root of ionic strength in sodium chloride solutions, with sodium chloride concentrations varying from 0.043 M to 1.0 M. Negative temperature coefficients for {lcub}(eta){rcub}(,o) indicate a decrease in the hydrodynamic volume of these model polymers with increasing temperature.; The relative zero-shear intrinsic viscosity change in water to that in aqueous 0.257 M sodium chloride solution was used to elucidate viscosity-structure relationships. This salt tolerance for polyelectrolyte models was found to decrease in the order AM-DAAM-NaAMPS terpolymers > AM-NaAMPS > AM-NaSEM > AM-NaA copolymers. The potential of these models as mobility control agents in Enhanced Oil Recovery is assessed in terms of the above salt tolerance, temperature and concentration effects on viscosity and hydrodynamic volume. |
