Investigation of polymer enhanced oil recovery (EOR) in microfluidic devices that resemble porous media

Literature review suggests that viscoelasticity of aqueous polymer solutions can considerably reduce the residual oil saturation compared to waterflooding without an increase of the viscous to capillary force balance (capillary number). Different working hypotheses have been proposed in literature to explain this effect, including (1) pulling, (2) stripping, (3) oil thread fow and (4)shear thickening. All of these mechanisms relate to the percolation Characteristics of viscoelastic polymers in porous media and are usually correlated to the degree of polymer viscoelasticity reflected in the magnitude of the longest relaxation time determined in oscillatory rheology. In this work oil displacement experiments performed in water-wet micromodels that resemble porous media having dierent average reservoir Qualities are presented. Silicon-edged micromodels provide visual access to the displacement process, hence, can lead to a more detailed displacement process description compared to experiments performed in cores. The experiments aim to verify the proposed viscoelastic oil displacement mechanisms and investigate if polymer viscoelasticity has a considerable impact on the residual oil mobilization, percolation and recovery in „secondary (at initial oil saturation)“and „tertiary (after extensive waterflooding)“ modes at typical reservoir shear rates. In addition, results obtained from micromodel flooding experiments will be compared to results from numerical simulation in order to test the validity of existing mathematical models to history-match micromodel flooding experiments. To match the simulation to the experimental results the oil saturation distribution is used, which is obtained for each cell based on image analysis of flooding experiments.