Construção de um arcabouço CFD parametrizável para o estudo de células de envelhecimento de fluidos de perfuração

Abstract

The aging of drilling fluids is traditionally assessed in cells rotated on roller devices, a configuration that does not establish a well-defined shear field. Impeller-equipped cells arise as an alternative, imposing controlled shear, but are subject to the formation of low-velocity regions, known as dead zones, which compromise treatment uniformity. In this work, a parameterizable Computational Fluid Dynamics framework was conceived and built from scratch, in free software, to simulate the flow of drilling fluids in such cells. The main contribution lies precisely in this parameterization: the geometry is fully defined by variables and the entire workflow, from geometry and mesh generation to solution and post-processing, is automated and reproducible, so that investigating new configurations requires no manual reconstruction. The fluid properties were determined experimentally by retort, gas pycnometry and a thixotropy test. The model, implemented in OpenFOAM, couples the two-phase Euler-Euler formulation, the solid-phase closure by the kinetic theory of granular flow, the Gidaspow drag force, the thixotropic Houska rheology with time evolution of the structural parameter, and the representation of the impeller rotation by the Multiple Reference Frame approach, over a geometry parameterized in Gmsh. The conservation of the solid-phase mass confirmed the numerical consistency of the model, whose solution proved to be independent of mesh refinement. The model reproduced a dead zone below the impeller, consistently evidenced by the velocity and shear-rate fields and by solids accumulation. The developed parameterizable framework constitutes a reproducible tool for future design and optimization studies of drilling-fluid aging cells.