Design and HIL Validation of an Effective Super-Twisting Controller for Stick-Slip Suppression in Drill-String Systems

2021 ◽  
Author(s):  
Abdelbasset Krama ◽  
Mohamed Gharib ◽  
Shady S. Refaat ◽  
Alan Palazzolo
Keyword(s):  
Power Plants ◽  
High Efficiency ◽  
Sliding Mode ◽  
Drill String ◽  
Experimental Investigations ◽  
Small Scale ◽  
Oil Well ◽  
Stick Slip ◽  
Rock Interaction ◽  
The Real

Abstract This paper presents a novel controller for drill string systems based on a super-twisting sliding mode theory. The aim is to eliminate the stick-slip vibration and maintain a constant drill string velocity at the desired reference value. The proposed controller inherently attenuates the torsional vibration while ensuring the stability and high efficiency of the drill string. A discontinuous lumped-parameter torsional model of vertical drill strings based on four components (rotary table, drill pipes, drill collars and drill bit) is considered. The Karnopp friction model is adopted to simulate the nonlinear bit-rock interaction phenomena. In order to provide a more accurate evaluation, the proposed drill string controller is implemented with the induction motor, a variable frequency drive and a gearbox to closely mirror the real environment of oil well drill strings. The increasing demand for prototyping and testing high-power plants in realistic and safe environments has led to the advancement of new types of experimental investigations without hurting the real system or building a small-scale prototype for testing. The dynamic performance of the proposed controller has been investigated with MATLAB software as well as in a novel hardware in-the-loop (HIL) testing platform. A power plant is modeled and implemented in the real-time simulator OPAL-RT 5600, whereas the controllers are implemented in the dSPACE 1103 control board. The results obtained through simulation and HIL testing demonstrate the feasibility and high performance of the proposed controller.

Modeling and Control of Coupled Torsional and Lateral Vibrations in Drill Strings

2015 ◽  
Author(s):  
Liu Hong ◽  
Jaspreet Singh Dhupia
Keyword(s):  
Sliding Mode ◽  
Good Control ◽  
Friction Torque ◽  
Lumped Parameter Model ◽  
Oil Well ◽  
Lateral Instability ◽  
Stick Slip ◽  
Rock Interaction ◽  
Lateral Vibrations ◽  
Lumped Parameter

Excessive vibrations of the drill strings, e.g., the stick-slip vibration, are the primary cause of premature failures and drilling inefficiencies in oil well drilling. To investigate and suppress such vibrations, this paper studies the dynamics of drill strings using a lumped parameter model, in which both the torsional stick-slip and lateral vibrations are taken into consideration. The friction torque due to the downhole bit-rock interaction, which plays a key role in stick-slip vibration, is modeled as a hysteretic dry friction function. Simulated results of this developed model are shown to have a close qualitative agreement with the field observations in terms of stick-slip vibrations. Afterwards, a sliding mode controller is applied to mitigate the undesired vibrations of drill strings. A good control performance in suppressing the stick-slip phenomenon is demonstrated for the proposed controller. However, numerical simulations also demonstrate that the control action can excite lateral instability in the system, which can result in impacts between the drill collars and the borehole wall due to the large amplitude in lateral vibrations. Thus, a proper choice of the control parameters is essential to suppress the vibrations in the drill strings. The developed lumped parameter model describing the coupled torsional and lateral response in the controlled drill strings presented in this paper can be used to aid in offline tuning of those control variables.

Study of stick–slip suppression and robustness to parametric uncertainty in drill strings containing torsional vibration tool using sliding-mode control

2021 ◽  
pp. 146441932110452
Author(s):  
Jialin Tian ◽  
Jie Wang ◽  
Siqi Zhou ◽  
Yinglin Yang ◽  
Liming Dai
Keyword(s):  
Torsional Vibration ◽  
Complex Dynamics ◽  
Sliding Mode ◽  
Parametric Uncertainty ◽  
Drill String ◽  
Lumped Parameter Model ◽  
Drilling Process ◽  
Drill Bit ◽  
Stick Slip ◽  
Drilling Operations

Excessive stick–slip vibration of drill strings can cause inefficiency and unsafety of drilling operations. To suppress the stick–slip vibration that occurred during the downhole drilling process, a drill string torsional vibration system considering the torsional vibration tool has been proposed on the basis of the 4-degree of freedom lumped-parameter model. In the design of the model, the tool is approximated by a simple torsional pendulum that brings impact torque to the drill bit. Furthermore, two sliding mode controllers, U1 and U2, are used to suppress stick–slip vibrations while enabling the drill bit to track the desired angular velocity. Aiming at parameter uncertainty and system instability in the drilling operations, a parameter adaptation law is added to the sliding mode controller U2. Finally, the suppression effects of stick–slip and robustness of parametric uncertainty about the two proposed controllers are demonstrated and compared by simulation and field test results. This paper provides a reference for the suppression of stick–slip vibration and the further study of the complex dynamics of the drill string.

A Semi-Analytical Study of Stick-Slip Oscillations in Drilling Systems

2010 ◽  
Vol 6 (2) ◽  
Author(s):  
B. Besselink ◽  
N. van de Wouw ◽  
H. Nijmeijer
Keyword(s):  
Dynamic Analysis ◽  
Limit Cycle ◽  
Analytical Approach ◽  
String Model ◽  
Drill String ◽  
Axial Stiffness ◽  
Torsional Vibrations ◽  
Stick Slip ◽  
Rock Interaction ◽  
Stiffness And Damping

Rotary drilling systems are known to exhibit torsional stick-slip vibrations, which decrease drilling efficiency and accelerate the wear of drag bits. The mechanisms leading to these torsional vibrations are analyzed using a model that includes both axial and torsional drill string dynamics, which are coupled via a rate-independent bit-rock interaction law. Earlier work following this approach featured a model that lacked two essential aspects, namely, the axial flexibility of the drill string and dissipation due to friction along the bottom hole assembly. In the current paper, axial stiffness and damping are included, and a more realistic model is obtained. In the dynamic analysis of the drill string model, the separation in time scales between the fast axial dynamics and slow torsional dynamics is exploited. Therefore, the fast axial dynamics, which exhibits a stick-slip limit cycle, is analyzed individually. In the dynamic analysis of a drill string model without axial stiffness and damping, an analytical approach can be taken to obtain an approximation of this limit cycle. Due to the additional complexity of the model caused by the inclusion of axial stiffness and damping, this approach cannot be pursued in this work. Therefore, a semi-analytical approach is developed to calculate the exact axial limit cycle. In this approach, parametrized parts of the axial limit cycle are computed analytically. In order to connect these parts, numerical optimization is used to find the unknown parameters. This semi-analytical approach allows for a fast and accurate computation of the axial limit cycles, leading to insight in the phenomena leading to torsional vibrations. The effect of the (fast) axial limit cycle on the (relatively slow) torsional dynamics is driven by the bit-rock interaction and can thus be obtained by averaging the cutting and wearflat forces acting on the drill bit over one axial limit cycle. Using these results, it is shown that the cutting forces generate an apparent velocity-weakening effect in the torsional dynamics, whereas the wearflat forces yield a velocity-strengthening effect. For a realistic bit geometry, the velocity-weakening effect is dominant, leading to the onset of torsional vibrations.

scholarly journals Stick-slip and Torsional Friction Factors in Inclined Wellbores

2018 ◽  
Vol 148 ◽  
pp. 16002 ◽  
Author(s):  
Ulf Jakob F. Aarsnes ◽  
Roman J. Shor
Keyword(s):  
High Frequency ◽  
String Model ◽  
Drill String ◽  
Distributed Model ◽  
Dynamic Friction ◽  
Stick Slip ◽  
Rock Interaction ◽  
Interaction Field ◽  
Friction Factors ◽  
Start Ups

Stick slip is usually considered a phenomenon of bit-rock interaction, but is also often observed in the field with the bit off bottom. In this paper we present a distributed model of a drill string with an along-string Coulomb stiction to investigate the effect of borehole inclination and borehole friction on the incidence of stick-slip. This model is validated with high frequency surface and downhole data and then used to estimate static and dynamic friction. A derivation of the torsional drill string model is shown and includes the along-string Coulomb stiction of the borehole acting on the string and the ‘velocity weakening’ between static and dynamic friction. The relative effects of these two frictions is investigated and the resulting drillstring behavior is presented. To isolate the effect of the along-string friction from the bit-rock interaction, field data from rotational start-ups after a connection (with bit off bottom) is considered. This high frequency surface and downhole data is then used to validate the surface and downhole behavior predicted by the model. The model is shown to have a good match with the surface and downhole behavior of two deviated wellbores for depths ranging from 1500 to 3000 meters. In particular, the model replicates the amplitude and period of the oscillations, in both the topside torque and the downhole RPM, as caused by the along-string stick slip. It is further shown that by using the surface behavior of the drill-string during rotational startup, an estimate of the static and dynamic friction factors along the wellbore can be obtained, even during stick-slip oscillations, if axial tension in the drillstring is considered. This presents a possible method to estimate friction factors in the field when off-bottom stick slip is encountered, and points in the direction of avoiding stick slip through the design of an appropriate torsional start-up procedure without the need of an explicit friction test.

scholarly journals Drillstring Failure: Analytical and Experimental Approach

2019 ◽  
Vol 300 ◽  
pp. 04004
Author(s):  
Edris Hassan ◽  
Jamil Abdo ◽  
Jan Kwak ◽  
Abdullah Al Shabibi
Keyword(s):  
Torsional Vibration ◽  
Oil And Gas ◽  
Drill Pipe ◽  
Oil And Gas Industry ◽  
Drill String ◽  
Design Parameters ◽  
Experimental Investigations ◽  
Torsional Vibrations ◽  
Stick Slip ◽  
The Impact

Drilling is one of the costliest activities in oil and gas industry due to the complexity of interactions with downhole rock formation. Under such conditions, the uncertainty of drillstring behaviour increase and hence it becomes difficult to predict the causes, occurrences, and types of failures. Lateral and torsional vibrations often cause failure of Bottom Hole Assembly (BHA), drillstring failure, drill bit and wall borehole damages. In this work, a model is presented to determine the impact of lateral and torsional vibrations on a drillstring during the drilling operation. The model aims to mimic real drillstring behaviour inside a wellbore with regards to its dynamic movements due to multiple real situations such as eccentricity of collars, drill pipe sections, and stick-slip phenomena occurring due to the interaction of the bit and the drillstring with the well formation. The work aims to develop a basis for determining critical operating speeds and design parameters to provide safe drilling procedures and reduce drill string fatigue failure. Lagrangian approach is used in this study to attain drillstring lateral and torsional vibration coupling equations. The nonlinear equations are solved numerically to obtain the response of the system. In this work, we also present a brief description of an in-house constructed experimental setup. The setup has the capability to imitate the downhole lateral and torsional vibration modes. Parameters from the experimental investigations are incorporated for validation of the mathematical models and for prediction of the drillstring fatigue life. Such investigations are essential for oil and gas industries as they provide solutions and recommendations about operational speed, lateral and torsional amplitudes measurements and corrections, and the conditions for avoiding occurrence of natural frequencies of the system.

EXPERIMENTAL INVESTIGATIONS OF MPPT IN A SMALL SCALE PHOTOVOLTAIC ENERGY SYSTEM BASED ON EXTREMUM SEEKING CONTROL

2013 ◽  
Vol 37 (3) ◽  
pp. 1001-1012 ◽  
Author(s):  
Her-Terng Yau ◽  
Chen-Han Wu
Keyword(s):  
Simulation Analysis ◽  
Sliding Mode ◽  
Energy System ◽  
Extremum Seeking ◽  
Experimental Investigations ◽  
Small Scale ◽  
Extremum Seeking Control ◽  
Power Point ◽  
Atmospheric Changes ◽  
Performance Of Algorithm

This study carried out experimental validation based on the simulation analysis results of Yau and Wu [1], and compared the MPPT situations of three kinds of extremum seeking control. It was proved that the sliding mode extremum seeking control has better transient response and steady-state characteristic, and changes the sunshine intensity to test the performance of algorithm, thus proving that the system can track the maximum power point rapidly in the environment with rapid atmospheric changes.

Multiscale System for Environmentally-Driven Infectious Disease with Threshold Control Strategy

2018 ◽  
Vol 28 (05) ◽  
pp. 1850064 ◽  
Author(s):  
Xiaodan Sun ◽  
Yanni Xiao
Keyword(s):  
Infectious Disease ◽  
Sliding Mode ◽  
Control Measures ◽  
Small Scale ◽  
Free System ◽  
Threshold Control ◽  
The Real ◽  
Parameter Values ◽  
Disease Free ◽  
Slow System

A multiscale system for environmentally-driven infectious disease is proposed, in which control measures at three different scales are implemented when the number of infected hosts exceeds a certain threshold. Our coupled model successfully describes the feedback mechanisms of between-host dynamics on within-host dynamics by employing one-scale variable guided enhancement of interventions on other scales. The modeling approach provides a novel idea of how to link the large-scale dynamics to small-scale dynamics. The dynamic behaviors of the multiscale system on two time-scales, i.e. fast system and slow system, are investigated. The slow system is further simplified to a two-dimensional Filippov system. For the Filippov system, we study the dynamics of its two subsystems (i.e. free-system and control-system), the sliding mode dynamics, the boundary equilibrium bifurcations, as well as the global behaviors. We prove that both subsystems may undergo backward bifurcations and the sliding domain exists. Meanwhile, it is possible that the pseudo-equilibrium exists and is globally stable, or the pseudo-equilibrium, the disease-free equilibrium and the real equilibrium are tri-stable, or the pseudo-equilibrium and the real equilibrium are bi-stable, or the pseudo-equilibrium and disease-free equilibrium are bi-stable, which depends on the threshold value and other parameter values. The global stability of the pseudo-equilibrium reveals that we may maintain the number of infected hosts at a previously given value. Moreover, the bi-stability and tri-stability indicate that whether the number of infected individuals tends to zero or a previously given value or other positive values depends on the parameter values and the initial states of the system. These results highlight the challenges in the control of environmentally-driven infectious disease.

Predictive-based sliding mode control for mitigating torsional vibration of drill string in the presence of input delay and external disturbance

2020 ◽  
pp. 107754632096099
Author(s):  
Roya Sadeghimehr ◽  
Amirhossein Nikoofard ◽  
Ali Khaki Sedigh
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
External Disturbance ◽  
Drill String ◽  
Smith Predictor ◽  
Input Delay ◽  
Drilling Process ◽  
Parameter Uncertainties ◽  
Stick Slip ◽  
Mode Control

Dealing with torsional vibrations and stick–slip oscillations of a drill string system is a challenging engineering task in the oil drilling process because of the harmful and costly consequences of such vibrations. In this article, the drill string system is modeled using a lumped-parameter model with four degrees of freedom, and the bit–rock contact is represented by a nonlinear function of a bit velocity. Also, tracking the desired velocity of a drill string system with known constant input delay is addressed in the presence of external disturbance and parameter uncertainties by applying the Smith predictor–based sliding mode control method. The performance of the smith predictor–based sliding mode control with input delay and disturbance in tracking the desired velocity and controlling the stick–slip oscillations is compared with the sliding mode control with/without input delay. The system output’s sensitivity to the delay parameter is also investigated, indicating how the bit velocity changes concerning the delay parameter. The proper choice of adaptation gain is determinative in the performance of the controller, and its impact is investigated. Moreover, the robustness of the smith predictor–based sliding mode control is shown by changing the weight on the bit parameter. Simulation results demonstrate the effectiveness of the proposed method.

scholarly journals Suppression of drill-string stick–slip vibration by sliding mode control: Numerical and experimental studies

2018 ◽  
Vol 29 (5) ◽  
pp. 805-825 ◽  
Author(s):  
VAHID VAZIRI ◽  
MARCIN KAPITANIAK ◽  
MARIAN WIERCIGROCH
Keyword(s):  
Mathematical Model ◽  
Sliding Mode Control ◽  
Close Agreement ◽  
Sliding Mode ◽  
Drill String ◽  
Numerical Results ◽  
Physical Parameters ◽  
Parameter Uncertainties ◽  
Stick Slip ◽  
Mode Control

We investigate experimentally and numerically suppression of drill-string torsional vibration while drilling by using a sliding mode control. The experiments are conducted on the novel experimental drill-string dynamics rig developed at the University of Aberdeen (Wiercigroch, M., 2010, Modelling and Analysis of BHA and Drill-string Vibrations) and using commercial Polycrystalline Diamond Compact (PDC) drill-bits and rock-samples. A mathematical model of the experimental setup, which takes into account the dynamics of the drill-string and the driving motor, is constructed. Physical parameters of the experimental rig are identified in order to calibrate the mathematical model and consequently to ensure robust predictions and a close agreement between experimental and numerical results for stick–slip vibration is shown. Then, a sliding mode control method is employed to suppress stick–slip vibration. A special attention is paid to prove the Lyapunov stability of the controller in presence of model parameter uncertainties by defining a robust Lyapunov function. Again experimental and numerical results for the control cases are in a close agreement. Stick–slip vibration is eliminated and a significant reduction in vibration amplitude has been observed when using the sliding controller.

Control of a class of multibody underactuated mechanical systems with discontinuous friction using sliding-mode

2016 ◽  
Vol 40 (2) ◽  
pp. 514-527 ◽  
Author(s):  
Yang Liu
Keyword(s):  
Sliding Mode ◽  
Direct Method ◽  
Drill String ◽  
Parametric Uncertainties ◽  
Underactuated Mechanical Systems ◽  
Stick Slip ◽  
Slip Regime ◽  
Sliding Mode Controllers ◽  
Control Objective ◽  
Mass Spring

This paper studies sliding-mode control of a class of multibody underactuated systems with discontinuous friction on the unactuated configuration variable taking into account parametric uncertainties. Global motion for this class system including sticking, stick-slip, and slip regimes are analysed, and their corresponding equilibria are identified. The control objective is to avoid the sticking and the stick-slip regimes while tracking a desired velocity in the slip regime. Three sliding-mode controllers which are robust to parametric uncertainties are proposed, and their stabilities are proved using the Lyapunov direct method. Two examples, a mass-spring-damping system and a drill-string system, are used to demonstrate the validity of the proposed controllers.

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