(with Ian Frigaard and Mark Martinez)

Spacer fluids, used in oilfields to displace the drilling mud, often present a rheological dilemma: high  viscosity is necessary for displacement, but prohibits long-distance pumping. In this Strategic Project, co-sponsored by Schlumberger and Trican Well Service Ltd., we aim to investigate the displacement flow under realistic conditions (see illustration for two typical configurations), and develop "smart spacer" fluids that dynamically adapt to the environment. When used in long horizontal wells, such spacer fluids would greatly reduce the number of wellheads and minimize environmental impacts, especially along the beautiful coast of British Columbia.

In a recent experiment, we used carbopol-based spacer fluids that undergo drastic viscosity changes upon an acid-base chemical reaction. The viscosity stratification induces a novel instability (see image c below) that greatly improves the efficiency of local mixing and the displacement. Numerical simulations have focused on miscible and immiscible displacements in a channel. Two typical runs are illustrated in images (d) and (e) below, with a displacing-to-displaced viscosity ratio of 0.05 (d) and 20 (e).