Consideration of Backreaming in Vertical Wells Closure Modeling in Salt Rock

Abstract

Summary The mobility of salt rocks may cause problems, such as stuck pipe, high torque, casing collapse, and hole closure, promoting enormous losses in different areas. The drilling mud weight generates a hydrostatic pressure that serves as a counterpressure to the displacement of the salt. Sometimes this measure is not enough, leading to the backreaming operation, which reconditions the diameter of the wellbore to its original state. Given the importance of backreaming during drilling operations in salt rocks, its incorporation into computational tools is necessary. Through the finite element method (FEM), we developed a program to identify and simulate the effects of the backreaming operations in vertical wells in the presence of salt layers. We proposed a simulator that associates 1D axisymmetric multilayers with unit thickness through a coupling strategy between them, considering a lesser number of degrees of freedom when compared to conventional 2D modeling. We checked the performance of multilayers strategy when compared with 2D axisymmetric modeling of the hole closure problem in the commercial software ABAQUS® (Dassault Systèmes, Vélizy-Villacoublay, France); for the radial displacement histories, the multilayer strategy presented similarity with ABAQUS for cases that consider interaction, with the advantage of a low computational cost provided by the 1D formulation. We demonstrated the modeling of backreaming through the proposed tool.