Hydrophobic Associative Copolymer with Favorable Properties for the Application in Polymer Flooding

Abstract A new thickener based on associative properties and its application in polymer flooding is discussed. The new thickener is an anionic, water-soluble copolymer containing pendant associative groups. These associative groups are based on a novel chemistry (patent application filed). The viscosity of the new copolymer shows superior behavior compared to existing technologies like partially hydrolyzed polyacrylamide (PHPA), especially at elevated temperature and in presence of salt respectively divalent ions. A viscosity of 33 mPas at 60°C could be obtained by adding 900 ppm of the new copolymer to synthetic sea water. In comparison, with a high molecular weight standard partially hydrolyzed polyacrylamide (PHPA) a value of only 3 mPas was reached. Moreover, the new polymer shows good resistance to shear during injection. Core flood experiments were run to prove that the new associative thickening polymer is applicable in the field. These data show injectivity into a 2 Darcy core. Moreover the apparent viscosity of the polymer flood in the core outperforms the values found with commonly used polymers by far. The residual resistance factor indicates low adsorption onto sandstone.