Local remesh procedure to model reaming in vertical oil wells drilled through salt rocks

Resumo

This paper presents an alternative methodology, based on cutting and adjusting finite elements, to model reaming of salt rocks during vertical wells drilling. The developed strategy ensures that the stress, deformation, and displacement fields are maintained after the remesh. To reach the pre-salt hydrocarbon reservoirs it is necessary to pass through thick layers of salt rocks. The mobility of these salt rocks can cause serious operational problems, such as the imprisonment of the drill string, casing collapse and annular entrapment of columns, compromising the casing integrity. Therefore, adequate monitoring of the well diameter must be done constantly throughout the entire drilling process. Thus, reaming procedures may be required to recondition the diameter of the well to its original state. The reaming strategy presented in this work is based on removing and adjusting mesh elements reestablishing the initial radius of the well in specific regions. This procedure improves the precision and realism of the simulations, avoiding the appearance of a gap between the mesh and drill bit passage. Stress graphs along the wellbore and comparisons with real wells data are used to enhance the phenomena understanding and validate the proposed methodology