Observer-Based Boundary Control Design for the Suppression of Stick–Slip Oscillations in Drilling Systems With Only Surface Measurements

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Halil Ibrahim Basturk
Keyword(s):  
Differential Equation ◽  
Angular Velocity ◽  
Linear Time ◽  
Control Design ◽  
Drill String ◽  
Friction Torque ◽  
Distributed Model ◽  
Drilling Process ◽  
Stick Slip ◽  
Surface Measurements

We develop an observer-based boundary controller for the rotary table to suppress stick–slip oscillations and to maintain the angular velocity of the drill string at a desired value during a drilling process despite unknown friction torque and by using only surface measurements. The control design is based on a distributed model of the drill string. The obtained infinite dimensional model is converted to an ordinary differential equation–partial differential equation (ODE–PDE) coupled system. The observer-based controller is designed by reformulating the problem as the stabilization of an linear time-invariant (LTI) system which is affected by a constant unknown disturbance and has simultaneous actuator and sensor delays. The main contribution of the controller is that it requires only surface measurements. We prove that the equilibrium of the closed-loop system is exponentially stable, and that the angular velocity regulation is achieved with the estimations of unknown friction torque and drill bit velocity. The effectiveness of the controller is demonstrated using numerical simulations.

scholarly journals Kinematics and dynamics analysis of new rotary-percussive PDM drilling tool

2021 ◽  
pp. 146134842198915
Author(s):  
Jialin Tian ◽  
Xuehua Hu ◽  
Liming Dai ◽  
Lin Yang ◽  
Yi Yang ◽  
...  
Keyword(s):  
Drill String ◽  
Structure Design ◽  
Drilling Process ◽  
Analysis Model ◽  
Drilling Tool ◽  
Stick Slip ◽  
Rate Of Penetration ◽  
Bottom Hole ◽  
Bottom Hole Assembly ◽  
The Impact

This paper presents a new drilling tool with multidirectional and controllable vibrations for enhancing the drilling rate of penetration and reducing the wellbore friction in complex well structure. Based on the structure design, the working mechanism is analyzed in downhole conditions. Then, combined with the impact theory and the drilling process, the theoretical models including the various impact forces are established. Also, to study the downhole performance, the bottom hole assembly dynamics characteristics in new condition are discussed. Moreover, to study the influence of key parameters on the impact force, the parabolic effect of the tool and the rebound of the drill string were considered, and the kinematics and mechanical properties of the new tool under working conditions were calculated. For the importance of the roller as a vibration generator, the displacement trajectory of the roller under different rotating speed and weight on bit was compared and analyzed. The reliable and accuracy of the theoretical model were verified by comparing the calculation results and experimental test results. The results show that the new design can produce a continuous and stable periodic impact. By adjusting the design parameter matching to the working condition, the bottom hole assembly with the new tool can improve the rate of penetration and reduce the wellbore friction or drilling stick-slip with benign vibration. The analysis model can also be used for a similar method or design just by changing the relative parameters. The research and results can provide references for enhancing drilling efficiency and safe production.

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.

Torsional Vibrations and Nonlinear Dynamic Characteristics of Drill Strings and Stick-Slip Reduction Mechanism

2019 ◽  
Vol 14 (8) ◽  
Author(s):  
Jialin Tian ◽  
Genyin Li ◽  
Liming Dai ◽  
Lin Yang ◽  
Hongzhi He ◽  
...  
Keyword(s):  
Torsional Vibration ◽  
Nonlinear Dynamic ◽  
Drill String ◽  
Drilling Process ◽  
Drill Bit ◽  
Torsional Vibrations ◽  
Reduction Mechanism ◽  
Nonlinear Dynamic Model ◽  
Stick Slip ◽  
Research Results

Torsional stick–slip vibrations easily occur when the drill bit encounters a hard or a hard-soft staggered formation during drilling process. Moreover, serious stick–slip vibrations of the drill string is the main factor leading to low drilling efficiency or even causing the downhole tools failure. Therefore, establishing the stick–slip theoretical model, which is more consistent with the actual field conditions, is the key point for new drilling technology. Based on this, a new torsional vibration tool is proposed in this paper, then the multidegree-of-freedom torsional vibrations model and nonlinear dynamic model of the drill string are established. Combined with the actual working conditions in the drilling process, the stick–slip reduction mechanism of the drill string is studied. The research results show that the higher rotational speed of the top drive, smaller viscous damping of the drill bit, and smaller WOB (weight on bit) will prevent the stick–slip vibration to happen. Moreover, the new torsional vibration tool has excellent stick–slip reduction effect. The research results and the model established in this paper can provide important references for reducing the stick–slip vibrations of the drill string and improving the rock-breaking efficiency.

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.

A Novel Backstepping Approach for the Attenuation of Torsional Oscillations in Drill Strings

2016 ◽  
Vol 248 ◽  
pp. 85-92 ◽  
Author(s):  
Farooq Kifayat Ullah ◽  
Franklyn Duarte ◽  
Christian Bohn
Keyword(s):  
Torsional Oscillation ◽  
Friction Model ◽  
Drill String ◽  
Cutting Process ◽  
Underactuated System ◽  
Drilling Process ◽  
Control Input ◽  
Nonlinear Phenomenon ◽  
Stick Slip ◽  
Torsional Oscillations

A common problem in the petroleum drilling process is the torsional oscillation generated by the friction present during the cutting process. Torsional oscillations in drill string are particularly difficult to control because the drill string is an underactuated system, it has a very small diameter to length ratio and it is driven at top end with the cutting process at the other end. These factors make the drill string prone to self-excited torsional vibrations caused by the stick-slip of the cutting bit. The system is modeled as a torsional pendulum with two degrees of freedom, where the upper inertia models the top drive and also part of the drilling pipes. The bottom inertia models the bottom hole assembly (BHA). The drill is considered to be a massless torsional spring-damper. The drill string is subjected to friction, which is formulated using a dry friction model. The friction model takes into account Coulomb friction, stiction and Stribeck effect. The latter friction component is the main nonlinear phenomenon that introduces negative damping at the bit; it leads to self-enforcing stick-slip torsional oscillations.In the approach of this work, for the attenuation of these self-excited oscillations a recursive backstepping control strategy is used and it is carried out in continuous time. The main contribution of this work, which is different from the backstepping approaches reported in the literature, is to use a nonlinear/artificial damping as virtual control input. The stability of the system has been proven in the sense of Lyapunov. The goal of the proposed algorithm is to deal the underactuation of the system and to provide a good response for different operating points. The effectiveness and robustness of the controller has been tested in simulations.

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.

Trajectory Tracking and Rate of Penetration Control of Downhole Vertical Drilling System

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Masood Ghasemi ◽  
Xingyong Song
Keyword(s):  
Trajectory Tracking ◽  
High Speed ◽  
Control Design ◽  
Second Phase ◽  
Drilling Process ◽  
Stick Slip ◽  
Rock Interaction ◽  
Rate Of Penetration ◽  
Modeling Uncertainties ◽  
Drilling System

This paper investigates a nonlinear control design for trajectory tracking and rate of penetration (ROP) control of the vertical downhole drilling process. The drilling system dynamics are first built incorporating the coupled axial and torsional dynamics together with a velocity-independent drill bit–rock interaction model. Given the underactuated, nonlinear, and nonsmooth feature of the drilling dynamics, we propose a control design that can prevent significant downhole vibrations, enable accurate tracking, and achieve desired rate of penetration. It can also ensure robustness against modeling uncertainties and external disturbances. The controller is designed using a sequence of hyperplanes given in a cascade structure. The tracking control is achieved in two phases, where in the first phase the drilling system states converge to a high-speed drilling regime free of stick–slip behavior, and in the second phase, the error dynamics can asymptotically converge. Finally, we provide simulation results considering different case studies to evaluate the efficacy and the robustness of the proposed control approach.

scholarly journals A New Efficient Adaptive Control of Torsional Vibrations Induced by Switched Nonlinear Disturbances

2019 ◽  
Vol 29 (2) ◽  
pp. 285-303 ◽  
Author(s):  
Maciej Wasilewski ◽  
Dominik Pisarski ◽  
Robert Konowrocki ◽  
Czesław I. Bajer
Keyword(s):  
Linear Quadratic Regulator ◽  
Drill String ◽  
Friction Torque ◽  
Nonlinear Behaviour ◽  
Torsional Vibrations ◽  
Linear Quadratic ◽  
Stick Slip ◽  
Direct Measurements ◽  
Excited Vibration ◽  
The Impact

Abstract Torsional vibrations induced in drilling systems are detrimental to the condition of the machine and to the effectiveness of the engineering process. The cause of vibrations is a nonlinear and unknown friction between a drill string and the environment, containing jumps in its characteristics. Nonlinear behaviour of the friction coefficient results in self-excited vibration and causes undesirable stick-slip oscillations. The aim of this paper is to present a novel adaptive technique of controlling vibrating systems. The scheme is based on the linear quadratic regulator and uses direct measurements of the friction torque to synthesize its linear dynamic approximation. This approach allows generating a control law that takes into account the impact of the friction on the system dynamics and optimally steers the system to the desired trajectory. The controller’s performance is examined via numerical simulations of the stabilization of the drilling system. The proposed solution outperforms the comparative LQG regulator in terms of the minimization of the assumed cost functional and the overall stability of the control system under the nonlinear disturbance.

Stick-Slip and Bit-Bounce of Deep-Hole Drillstrings

2000 ◽  
Vol 122 (2) ◽  
pp. 78-82 ◽  
Author(s):  
A. Baumgart
Keyword(s):  
Angular Velocity ◽  
Nonlinear Differential Equations ◽  
Equations Of Motion ◽  
Hydraulic Pressure ◽  
Drilling Process ◽  
Initial Value ◽  
Stick Slip ◽  
Bottom Hole ◽  
Weight On Bit ◽  
Torque On Bit

A mathematical model for the drilling process is derived and solved numerically as an initial value problem. The equations of motion are nonlinear differential equations for longitudinal, lateral, and rotational motion of the pipe as well as for the rate of flow and pressure of the mud. The model comprises a mud (Moineau) motor which rotates the bit relative to the lower end of the pipe. The model accounts for buckling of the pipe due to excessive torque and longitudinal forces, as well as for the effect of hydraulic pressure on the deformed pipe. Weight on bit and torque on bit are computed from characteristic curves which are functions of the penetration of the bit into the rock and the angular velocity of the bit. Numerical simulations show self-excited oscillations of the drillstring, including bit take-off from the bottom hole and large amplitudes in the bit’s angular velocity. [S0195-0738(00)00602-6]

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