Displacement of viscoplastic fluids in eccentric annuli: numerical simulation and experimental validation

Abstract

In completion of oil and gas wells, zonal isolation requires proper cement placement with adequate bonding to the casing and formation. To achieve a successful cementing operation, the cement slurry must be properly designed to enable effective displacement of the drilling fluid from the annulus between the casing and well bore. This is a complex process, involving time dependent displacement of non-Newtonian fluids in eccentric annuli. The rheology, flow rate, and interfacial mixing of these fluids have direct impact on the displacement efficiency. Reliable computational modelling of the dynamics of the displacement process is critical to pre-job design and post-job analysis of the cementing job. Furthermore, experimental data are also required to directly evaluate numerical predictions. This paper reports on the development of a laboratory helical-flow device with adjustable inner-pipe eccentricity and rotation for flow-visualisation studies of annular-displacement flow of miscible fluids. Displacement experiments are conducted with a variety of visco plastic fluids in various annular geometries and flow conditions to produce data that can be compared with and used to validate numerical simulations produced by a new 3- D displacement model