Modelagem de poços direcionais utilizando elementos finitos tridimensionais no Abaqus

Abstract

This work proposes a three-dimensional modeling strategy for directional wells intersecting salt rocks, aiming to predict the closure of these formations due to the creep phenomenon. Drilling thick layers of salt rock, as in pre-salt fields, poses significant operational challenges, mainly due to the tendency of these rocks to deform over time, reducing the well diameter and, in extreme cases, leading to the entrapment of the drill string. Complexity increases in inclined wells, where angular variation breaks the symmetry observed in vertical wells and requires more sophisticated numerical approaches to adequately represent the system. The modeling was carried out using the ABAQUS software, which applies the Finite Element Method (FEM) in its three-dimensional formulation and allows the implementation of customized constitutive laws through subroutines. A comparative analysis was initially conducted between two creep laws: the Double Mechanism of Deformation (MDD), widely used in national literature, and the Double Power Law (DPL), which showed compatible results with greater computational efficiency. A three-dimensional model of a vertical well with a single lithology was then verified through comparison with an axisymmetric Abaqus model previously validated by the research group. This verification used the vertical geometry due to the scarcity of threedimensional directional well models in the literature—only one such study, by Poiate (2012), was identified and used as the basis for Case Study II. After verification, simulations were performed with varying inclinations and later with multiple lithologies. The results were analyzed focusing on the displacements of the inner walls of the well. The investigation showed that, although the DPL produced slightly higher displacements compared to the MDD, the difference was technically acceptable, and its application demonstrated approximately 23 times higher computational efficiency in two-dimensional models. For the three-dimensional models analyzed, well inclination had limited influence on radial displacements, suggesting that in certain scenarios, two-dimensional modeling may be sufficient. This research contributes to the understanding of the viscoplastic behavior of salt rocks in directional wells, providing technical upport for the design of safer and more efficient wells in salt-bearing regions.