This topic will cover many aspect of drillstring mechanics, going from bit and BHA modeling for directional drilling applications in unconventional plays, to tubulars mechanics related to torque, drag, buckling, and casing wear.

The first part of this presentation starts by focusing on directional drilling in explaining how the interaction between the PDC bit, the rock formation and the BHA affects the directional response of the drilling system. After a summary of modeling steps and laboratory results, this presentation will show results of case studies in shale play environment, where PDC bit and BHA selection is of utmost importance to control the well trajectory. Calculations of inclination and azimuth each foot or so enable also to highlight the presence of local doglegs using standard surveys, bottom hole assembly data and steering parameters.

The second part of the discussion is dedicated to the mechanical behavior of drill string in 3D wellbore. Extensive research was conducted a few years ago to be able to calculate deflection and contact points between tubulars and the borehole without using finite element analysis. This research has led to a robust and accurate model able to compute simultaneously torque, drag and buckling, and also estimate casing wear. Case studies highlighting the necessity of such advanced computations are then shown.