Characterization of acrylamide polymers for enhanced oil recovery

Four different copolymers, of acrylamide and acrylic acid, acrylamide and 2-acrylamido-2-methyl propane sulfonic acid, N,N-dimethylacrylamide and acrylic acid, and N,N-dimethylacrylamide and 2-acrylamido-2-methyl propane sulfonic acid (sodium salts), were prepared. The copolymers were characterized by their intrinsic viscosities and monomer ratios and with IR, H-1-NMR, and X-ray diffraction (XRD) spectroscopy. No crystallinity was observed by differential thermal analysis, and this was well supported by XRD. All the polymers showed low decomposition temperatures. A number of decomposition temperatures were observed in differential thermogravimetry thermograms because of the elimination of gases such as CO2, SO2, CO, and NH3. The replacement of the acrylate group with a sulfonate group produced polymers that were more compatible with brine, whereas the replacement of acrylamide with a more hydrophobic group such as N,N-dimethylacrylamide produced a more shear-resistant polymer. A N,N-dimethylacrylamide-co-sodium-2-acrylamido-2-methyl propane sulfonate copolymer was better with respect to thermal stability when the polymer solution was aged at 120degreesC for a period of 1 month. (C) 2003 Wiley Periodicals, Inc.