Single-Phase Flow of Aqueous Polymer Solutions Used in Enhanced Oil Recovery: An Experimental and Numerical Approach

Abstract

Abstract Chemical Enhanced Oil Recovery with polymer flooding allows to decrease the mobility ratio between oil and water and therefore increase the sweep efficiency in the reservoir through different mechanisms that take place, such as: pressure drops and viscosity changes of the injected fluid. The main objective of this work is to assess the friction factor coupled with the pressure drop evaluation, to define its impact in the polymer injection through porous media. The evaluation will allow the determination of the drag enhancement and drag reduction zones of the polymer solutions, which contributes to understand the additional oil recovery. A total of 12 polymer solutions were selected for this investigation and to establish numerical and experimental comparisons. Two types of commercial hydrolyzed polymers (Flopaam 6035S and Hengfloc 63023) were used at three different concentrations (500, 1000 and 1500 ppm). The polymer solutions were prepared using two different approaches (induced mechanical degradation and non-sheared). Experiments were performed injecting the polymer solutions in Bentheimer core samples. The evaluation was performed using a fourfold approach: 1) Three different rheological models were applied (Ergun (1949), Tiu et al. (1997) y Al Fariss (1990)), to determine mechanical parameters such as friction factor, Reynolds number and Weissenberg number. 2) Detailed relationship between viscosity as a function of pressure drop. 3) Defining correlations between the viscoelastic behavior of polymeric solutions and pressure drop associated to each experiment. 4) Numerical analysis using CMG Stars simulator, allowing Absolute Average Error (AAE) calculation. The additional increase in differential pressure indicates that shear and frictional forces are not the main determinants during the flooding process. The results indicate that the polymer viscoelasticity is the main reason of this increase while polymer undergo deformation. The work provides a comprehensive evaluation to characterize the pressure observed during the flow of polymer in porous media.