Efficient Displacement Of Fluids Using A Viscous Shear-Thinning Spacer

The miscible displacement flow of a light fluid by a heavy fluid, while using a spacer between these fluids, is considered. The effects of the spacer viscosity on the displacement efficiency are studied experimentally and numerically. In our experiments, the displacing and displaced fluids are Newtonian fluids (saline solutions). A shear-thinning xanthan solution is used to create a wide range of viscosity ratios (m) between the spacer and the other fluids (m approximate to 1-20000). The experiments are performed in a long inclined square cross-section duct, and the experimental results are delivered via a novel image capturing/processing technique. The results show that using a highly viscous shear-thinning xanthan solution as a spacer can result in a complete removal of the displaced fluid from the duct, increasing the displacement efficiency. As a complementary approach, a computational model is developed using OpenFOAM to gain more insight into the flow, showing good agreement with the experimental data. The numerical simulations reveal that the shear-thinning properties of the highly viscous spacer are necessary to increase the displacement efficiency.