Finite element analysis of a DP-Slip System

As an important tool for tripping of a drill-string, a Drill Pipe-slip (DP-slip) system directly affects both the service life of a DP and the target depth it can reach. In this study, a Finite Element (FE) model implemented in ABAQUS is developed to simulate interactions within a DP-slip system. For this model, materials, geometric dimensions, loads, and boundary conditions were
determined from an actual DP-slip system. Based on this model, a series of case studies were carried out, with a particular focus on the geometric parameter optimization of the slip insert with regards to the stress distribution in the insert and the DP, wherein factors like a longitudinal groove number in the slip insert and a number of row spacings are considered. Numerical results show that the stress distribution in the direction of DP axis and along its circumference change for both the DP and slip insert and that the stresses on the inner surfaces are higher than of the ones on the outer surfaces. The maximum stress of the inner surface of the DP occurs in the gap between each of the two slip inserts, making the stress of the inner surface of the DP oscillate periodically along its circumference. For the stress distribution of the slip insert, the maximum stress occurs at its lower end. By comparing the stress distributions of the DP and the slip insert, the optimized values of the longitudinal groove number of the slip inserts and the row spacing of the slip insert can be identified as 3 and 0, respectively. The method as well as the optimized values can be of significance
for designing new types of slip inserts