| Cement slurries are used for the construction of oil wells as deep as 30,000 ft (9,000 m). The severe performance requirements for such materials have prompted the search for appropriate fiber reinforcement to improve the cement sheath's tensile strength, impact resistance, and fracture toughness, without decreasing the slurry's pumpability. A continuum theory for dilute suspensions of large-aspect-ratio particles is applied to the flow of fiber suspensions in a simplified three-dimensional fluid flow. The fluid itself is modeled as a non-Newtonian fluid, following the power-law description. A numerical analysis using the finite element method was carried out to investigate the velocity profile, the fiber orientation components and shear stresses on the inner and outer walls for a constant pressure drop of fiber-reinforced cement slurries through an eccentric annulus at elevated temperatures. The material parameters were determined in an experimental test program. Selected results over a range of eccentricities, radial ratios, fluid properties and flow parameters are presented to illustrate the practical significance of the model for oil well applications. |
