The study of stratified solid liquid annular flows is of great interest of the petroleum engineering, specifically in the drilling area. This kind of flow describes the phenomena involved in the transport of the solids generated by the bit during the drilling of a horizontal of highly inclined well. In these operations there is tendency due to the action of gravitational forces of solids deposition in the lower part of the annular region foumed by the wellbore walls and the drill column. One approach is the well known Two Layer Model, originally proposed by the mining industry to simulate the transport of solids at high concentrations in pipes. This model has been adapted to the problem of drilled cuttings transport, by the introduction of elements to model the non Newtonian behavior of the fluid and the annular geometry and is currently in use for design and troubleshooting in drilling operations. Some limitations of the model in the reproduction of the role of rheology in the transport of solids motivated the formulation of more precise hypothesis. This paper deals with the analysis of the effect of the improvements in the final results of the model. Such improvements include the experimental determination of interfacial friction between the solids bed and the suspension new criteria for solid liquid slip conditions and the choice of different rheological models.
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