Eficiência de recuperação de fluidos viscosos através da injeção de fluidos viscoplásticos em tubos capilares

Abstract

The liquid-liquid displacement in capillary tubes has been constantly analyzed on thelast decades. Currently, the comprehension of this kind of problem is of great rele-vance, as it involves several applications on oil recovery and on cementing of oil wells.In the present work we are interested in understanding how the viscosity ratio, capil-lary number and the non-newtonian properties, viscoplasticity in particular, affects theprofile of the drop of the displacing liquid and the displacement efficiency. In a simpleexperimental apparatus, a viscoplastic solution is used to displace a Newtonian liquidin a capillary tube. The images of the interface are recorded during the test. Fromthese images, we have the interface shape and the thickness of the displaced liquidattached to the wall as a function of the investigated parameters. By a simple volumebalance, we also have a measure of the displacement efficiency. It is shown that thedisplacement efficiency and the liquid film attached to the wall doesn’t follow the sametrend. In addition, instabilities were found along the length of the drops from the cen-ter to the injection point. Results indicates a limitation on the displacement efficiencyregarding viscosity ratios less than 1. Finally, it is also observed that the displacementefficiency is greater than the equivalent Newtonian case, while the thickness of thedisplaced liquid attached to the wall is smaller.