Benchmarking of Industrial Stick-Slip Mitigation Controllers

Aarsnes, Ulf Jakob F.; Meglio, Florent Di; Shor, Roman

doi:10.1016/j.ifacol.2018.06.382

Cited by 17 publications

(10 citation statements)

References 15 publications

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“…As we can only act on the orientation by modifying the BHA velocity (using a top-drive actuation), it might be of interest to consider feedback laws that have been designed to control BHA velocity while avoiding the effects of stickslip [19,20]. For a majority of drilling rigs in the field, the actuation is done through AC electric top drives, using a variety of variable frequency drives which are capable of highly accurate, high frequency, rotary speed control.…”

Section: Feedback Controllers For the Bha Velocitymentioning

confidence: 99%

“…Two types of stick-slip mitigation controllers have been widely deployed: the older SoftTorque-SoftSpeed systems and the newer ZTorque systems. These control laws have been proved to be more efficient compared to simple stiff PI controller [20]. Such control laws have been improved in [19] by completing them by a feed-forward action that does not disturb their closed-loop behavior.…”

Section: Feedback Controllers For the Bha Velocitymentioning

confidence: 99%

“…The feedback control law is used to "artificially" have the top-drive match the impedance of the drill-pipe, ζ p = J p G p ρ. The block diagram of the Z-torque control law is given in Fig 5. It has been shown in [20] that the Z-torque control law effectively removes stick-slip oscillations at the costs of delivering high instantaneous torque to the top drive to allow for impedance matching through rapid velocity changes and a significantly slower response in rotational velocity of the top-drive. Z-torque also requires extra instrumentation, namely a measurement of the torque acting from the drill string on the top-drive, to work effectively.…”

Section: Softtorque and Ztorquementioning

confidence: 99%

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Closed-loop tool face control with the bit off-bottom

Auriol

Shor

Aarsnes

et al. 2020

Journal of Process Control

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In this paper, we develop three methods to achieve reliable closed-loop, tool face control for directional drilling operations. This is a necessary step to achieve closed-loop, automated directional guidance. Our algorithms combine existing industry top-drive controllers with new control approaches. The torsional model we use for the drill string has been field validated and takes into account the Coulomb friction between the drill string and the borehole. These distributed friction terms are either assumed known (or measured) or can be estimated using a state-observer. In this work, we improve such a state-observer to obtain an estimation of the tool face orientation in real-time. We then propose different approaches to control the tool face. The first method is based on a feed-forward control law. It uses the flatness of the model and the estimation of the orientation to generate an admissible trajectory which is then tracked. In the second procedure, we require a stable rotation off-bottom before smoothly changing the reference to zero to stop bit rotation. This change of reference induces a change of orientation that can be estimated and finally compensated by repeating the procedure. Finally, the last method uses a series of trapezoidal setpoint inputs-bumps-to calculate the change in downhole tool face per change in surface orientation before arriving at the correct tool face after three iterations. These three algorithms are illustrated in simulations of field scenarios and their effectiveness and limitations, depending on the reliability and availability of downhole orientation data, are discussed.

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Section: Feedback Controllers For the Bha Velocitymentioning

confidence: 99%

Section: Feedback Controllers For the Bha Velocitymentioning

confidence: 99%

Section: Softtorque and Ztorquementioning

confidence: 99%

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Closed-loop tool face control with the bit off-bottom

Auriol

Shor

Aarsnes

et al. 2020

Journal of Process Control

Self Cite

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“…It may also raise safety issues. Control mechanisms may be used to reduce these vibrations in the system [1], [2]. However, such control mechanisms often depend on the rock properties that the system is drilling into.…”

Section: Introductionmentioning

confidence: 99%

A Sensing and Computational Framework for Estimating the Seismic Velocities of Rocks Interacting With the Drill Bit

Auriol

Kazemi

Shor

et al. 2020

IEEE Trans. Geosci. Remote Sensing

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We have developed a sensing and computational framework to estimate seismic velocities of rocks interacting with the drill-bit during the drilling process. The performance of drilling depends on our knowledge of the subsurface. The interaction between the drill-bit and rock can introduce severe vibrations in the drill-string and result in safety and performance issues. However, we can use seismic waves radiated from drill-bit-rock interactions to determine seismic velocities of the rocks interacting with the drill-bit. Our approach consists of a distributed (wave equation) representation of the dynamics of the drill-string for which we show (using Riemann's invariants and a backstepping approach) that it is possible to express the force-on-bit as a function of the top-drive force and the topdrive velocity, without requiring explicit information about the subsurface properties. We also show that seismic waves generated by drill-bit-rock interaction can be modelled as functions of the force-on-bit and of rock velocities. The rock velocity independent formulation of the force-on-bit, along with modelling of the seismic waves generated by drill-bit-rock interaction as a function of force-on-bit and rock velocities allow us to estimate seismic velocities of rocks interacting with the drill-bit. We use the alternating minimization algorithm to estimate the velocities. Numerical examples on simulated data are indicators of the validity of the approach. The proposed methodology is the first step towards a subsurface-aware drilling system.

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“…Recently, few attempts have been made by researchers to compare different control methods. Authors in [35] evaluate how three different top-drive feedback controllers influence the occurrence of a stick-slip limit cycle in a rotating drillstring, namely, the industry standard stiff, high-gain controller, SoftTorque, and ZTorque. They have provided a map for each controller indicating the existence and amplitude of oscillations, parametrized in the key friction parameters.…”

Section: Introductionmentioning

confidence: 99%

Parametric analysis of a sliding-mode controller to suppress drill-string stick-slip vibration

et al. 2020

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Despite a significant research effort to understand and mitigate stick-slip in drill-strings, this problem yet to be solved. In this work, a comprehensive parametric robustness analysis of the sliding mode controller has hitherto been performed. First, a model verification and extensive parametric analysis of the open-loop model is presented. This is followed by a detailed parametric analysis of the sliding-mode controller based closed-loop system for two cases, (i) an ideal actuator with no delay or constraint and (ii) a realistic actuator with delay or/and constraint. It is shown that though the proposed controller works robustly across a wide range of parameters, in the absence of delay, it fails in the presence of a delay, thereby limiting its practical application. Experimental results are included to support these claims. This work underlines the importance of including the inherent system characteristics during the control design process. Furthermore, the parametric analysis presented here is aimed to act as a blue-print for testing the efficacy of relevant control schemes to be proposed in the future.

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Benchmarking of Industrial Stick-Slip Mitigation Controllers

Cited by 17 publications

References 15 publications

Closed-loop tool face control with the bit off-bottom

Closed-loop tool face control with the bit off-bottom

A Sensing and Computational Framework for Estimating the Seismic Velocities of Rocks Interacting With the Drill Bit

Parametric analysis of a sliding-mode controller to suppress drill-string stick-slip vibration

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