Proportional-Derivative Control of Stick-Slip Oscillations in Drill-Strings

Wei Lin,Yang Liu,E Manoach,M Wiercigroch,S Stoykov

doi:10.1051/matecconf/201814816005

Wei Lin, Yang Liu + Show 3 more

Open Access

https://doi.org/10.1051/matecconf/201814816005

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Abstract

Stick-slip oscillation in drill-string is a universal phenomenon in oil and gas drilling. It could lead to the wear of drill bit, even cause catastrophic failure of drill-strings and measurement equipment. Therefore, it is crucial to study drilling parameters and develop appropriate control method to suppress such oscillation. This paper studies a discrete model of the drill-string system taking into account torsional degree-of-freedom, drill-string damping, and highly nonlinear friction of rock-bit interaction. In order to suppress the stick-slip oscillation, a new proportional-derivative controller, which can maintain drill bit’s rotation at a constant speed, is developed. Numerical results are given to demonstrate its efficacy and robustness.

Highlights

For conventional rotary drilling, drill-string is a principal component for the entire drilling system
In oil and gas drilling, stick-slip behavior exists in 50% of drilling time [1], and the whipping and high rotation of the drill bit may cause bit bouncing and whirling motion [2]
Where Φ is the rotational position of lumped mass, J is the rotational inertia matrix, C is the torsional damping matrix, and K is the torsional stiffness matrix, T is the torque of friction between drill bit and rock, and U is the control torque applied on the rotary table

Summary

Introduction

Drill-string is a principal component for the entire drilling system. As shown in Fig. (a), a typical drilling system is composed of a rotary table, a slender drill pipe, a drill collar, and a drill bit. When drill pipes transmit the drive torque from rotary table to drill bit, deformations in drill pipes are very complex, especially considering the constraints of the borehole. The slenderness of the drill pipe makes it prone to exhibit undesired oscillations, including bit bouncing, lateral oscillation, torsional oscillation, and whirling motion. In oil and gas drilling, stick-slip behavior exists in 50% of drilling time [1], and the whipping and high rotation of the drill bit may cause bit bouncing and whirling motion [2]. The interaction between drill-strings and borehole makes drilling system uncertain [4]

Drill Bit b

The remaining sections of this paper are organized as

Simulation Results

Acceleration of drill bit

Control on

Conclusions