Experimental and numerical studies of viscoelastic polymer solution flows through constricted micro capillary

Mário Pareto¹; Danmer Maza¹; Márcio S. Carvalho¹

¹ Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio)

doi:10.20906/CPS/COB-2015-0297

Resumo

The injection of polymer solution is used as an Enhanced Oil Recovery method in many oil fields. The addition of polymer molecules to the injected water increases its viscosity, leading to a better mobility ratio between the oil and water phases and consequently larger volumes of produced oil. However, despite recent progress, the fundamental understanding on how elastic properties of a polymer solution improve oil recovery is still not complete. Because of the complexity of the flow, different mechanisms for residual oil mobilization have been proposed. The relative importance of each of these mechanisms is not clear. The geometry of a single pore throat resembles that of a constricted micro capillary. Here, we study experimentally and numerically the flow of viscoelastic solution in this geometry. The goal was to determine the pressure drop - flow rate relation as a function of geometry and rheological properties of the liquid. The Oldroyd-B and Fene-CR constitutive equations that approximate viscoelastic behavior of polymer solutions were used, together with momentum and continuity equations, to model two-dimensional axisymmetric flow through micro capillaries. The equation system was solved with the Finite Element Method. The results show how the viscoelastic properties can affect the stress field in the liquid and the pressure drop - flow rate relation. Experimental Results show that, above a certain flow rate, the pressure drop is not fully described by the viscous flow and elastic effects need to be taken into account. The reduced mobility of the water phase due to the extension of polymer molecules, as they flow through the converging-diverging channel, can be used to improve oil displacement in porous media.

Palavras-chave: Viscoelastic liquids; Extensional flow; Polymer solution; Finite element method