Efficacy of Synthetic Hydrophobic Associative Tetrapolymers for Improved Recovery of Viscous Oil in Sandpack Model

This study examined the suitability of hydrophobic associative tetrapolymers (HATs) for enhanced oil recovery through sandpack flooding. Two novel hydrophobic associative tetrapolymers, herein designated as HAT-1 and HAT-2 were synthesised via free radical polymerisation and the structures were confirmed by Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H NMR). HAT-1 composed of acrylamide - hydroxyethyl methacrylate - N- vinyl pyrrolidone - N,N-dimethyl acrylamide and HAT-2 consisted of acrylamide - sodium 2-acrylamido-2-methyl propane sulphonate - diallyldimethylammonium chloride - lauryl methacrylate. Comparative tests were carried out under laboratory conditions on the oil displacement efficiencies of the two HAT polymers. The incremental oil recovered using polymer HAT-1 and HAT-2 injection after water flooding were 33.7% and 36.2%, respectively. Combining the oil recovered from water flooding followed by polymer flooding both scenarios, the cumulative recovered using HAT-2, 83.3 % was relatively higher than that of HAT-1, 74.4%. These values are relatively high from the economic perspective. Based on brine viscosity enhancement, mobility ratio reduction and additional oil recovery, HAT-2 polymer exhibited a relatively higher potential to improve oil recovery for reservoirs with characteristics similar to the experimental conditions for this work.