This paper presents the results of an extensive study aimed at describing the viscoelastic properties of polymer solutions for enhanced oil recovery. Using natural and artificial cores and polymer solutions with different storage factors, core floods were performed to examine the influence of viscoelasticity of polymer solutions on flow behaviour and oil recovery.

From the experimental results, it appears that beyond a critical injection rate the viscoelasticity of polymer solutions is reflected by increasing of effective viscosity. This critical injection rate is dependent on the concentration and degree of hydrolization (HPAA), molecular weight of polymers, core permeability, salinity and temperature. Therefore the viscoelastic core flow behaviour of polymer solutions can be adjusted to specific reservoir conditions by variation and optimization of these parameters.

To describe and quantify the viscoelastic effects by means of experimental results, a model based on Maxwell-Fluid-Relation is applied. Using the proposed model, the model index É can be determined, which represents the viscoelastic behaviour of polymer solutions in porous media.

It is found that not the relaxation time, but the model index É is the parameter which should used for quantifing this viscoelastic behaviour of polymer solutions in porous media.

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