Rotary Steerable Directional Drilling Stick/Slip Mitigation Control

Abstract

This paper details the online-identification-based adaptive design of a stick/slip minimization algorithm and top-drive servo control for Rotary Steerable System (RSS) directional drilling tools. Stick/slip in this context refers to the downhole angular velocity variation of the bit about a nominal value. The basic pole placement controller designs are SISO linear but recursively evaluated based on an online Recursive Least Squares (RLS) identification of the open-loop plant parameters. System architecture implications for the stated algorithm are discussed, and simulation results included with and without adaptive stick/slip mitigation.