Viscoelastic behavior of crude oil-polymer emulsions

This study focuses on the investigation of the viscoelastic behavior of crude oil-Alcoflood polymer (AFP) emulsions in terms of storage modulus, loss modulus, and complex modulus. Three different types of AFP were examined in this investigation. North Sea crude oil was used to prepare the oil-polymer emulsions. The polymer and oil concentrations exhibit a strong influence on the behavior of complex modulus vs frequency. The effect of polymer and oil concentrations is more pronounced at low frequency. This effect diminishes with frequency. For the three polymers used, the apparent complex modulus increases significantly with the concentration of polymer and crude oil. The crude oil phase gradually increases the complex modulus of the emulsions. The complex modulus values of AF1275 and AF1285 emulsions are similar to each other and significantly higher than that of the emulsions of AF1235. The polymer concentration strongly increases the emulsion complex modulus. For a low polymer concentration of 2000 ppm, the aqueous solutions and oil emulsions exhibit viscoelastic behavior with a liquid-like response at low frequencies and a solid-like response at high frequencies. The addition of crude oil lowers the crossover frequency. However, at a higher polymer concentration of 10 000 ppm, both aqueous solutions and emulsions exhibit only elastic behavior.