Hydrophobically Modified Sulfonated Polyacrylamides for IOR: Correlations between Associative Behavior and Injectivity in the Diluted Regime

Abstract : We report new experimental correlations between the injectivity through polycarbonate membranes and associative properties of random Hydrophobically Modified Water Soluble Polymers (HMWSP) with sulfonated polyacrylamides (SPAM) backbones and variable compositions in hydrophobic units. The investigations are focused on both their associative behavior in the diluted and semi-diluted regime and their injectivity under frontal filtration conditions in the diluted regime. Results from viscosimetric and dynamic light scattering measurements indicate the existence of thresholds in terms of amount (≥ 0.5 mol%) and mass (≥ C12) of alkyl hydrophobic units above which interchain interactions arise. These interactions are evidenced by the presence of multichain aggregates in diluted solutions and by enhanced thickening abilities in semidiluted solutions. The filtration study was performed with capillary pore membranes (track-etched) in the Darcy regime under constant-flow rate and high Jamming Ratio conditions. Results show that: - injection of diluted solutions of HMWSP without interchain interactions (i.e. with composition in hydrophobic units below the above mentioned thresholds) does not lead to significant mobility and permeability reductions as compared to the injection of a reference Water Soluble Polymer (WSP); - injection of diluted solutions of HMWSP with interchain interactions leads to significant mobility and permeability reductions; - HMWSP-induced mobility and permeability reductions are essentially due to irreversible polymer adsorption on the pore walls and not to the formation of filter-cakes; - HMWSP adsorbed layers thicknesses are limited by the effective stress applied by the solution's flow in the pores.