Performance analysis of proportional-integral feedback control for the reduction of stick-slip-induced torsional vibrations in oil well drillstrings

2017 ◽  
Vol 398 ◽  
pp. 28-38 ◽  
Author(s):  
Hugo L.S. Monteiro ◽  
Marcelo A. Trindade
Keyword(s):  
Performance Analysis ◽  
Feedback Control ◽  
Oil Well ◽  
Torsional Vibrations ◽  
Stick Slip ◽  
Proportional Integral ◽  
Integral Feedback

Draft: Stick-Slip Motions of a Rotor-Stator System

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Nicholas Vlajic ◽  
Chien-Min Liao ◽  
Hamad Karki ◽  
Balakumar Balachandran
Keyword(s):  
Dry Friction ◽  
Torsional Oscillation ◽  
Flexible Structures ◽  
Oil Well ◽  
Torsional Vibrations ◽  
Dimensional Model ◽  
Torsional Mode ◽  
Stick Slip ◽  
Finite Dimensional ◽  
Motion State

In the current study, the authors examine the torsional vibrations of a rotor enclosed within a stator subjected to dry friction. Through the experiments, it is demonstrated that forward whirling of the rotor occurs while in contact with the stator, backward whirling occurs with contact, as well as impacting motions, which are characterized by nonsynchronous whirling with rotor-stator collisions. While undergoing these motions, the torsional oscillations are excited by stick-slip interactions. Experimental data are presented to show the presence of a stable torsional mode dominated motion while subjected to stick-slip forces during dry-friction whirling. In this motion state, the torsional oscillation response occurs at a combination of frequencies including drive and whirl frequencies. A finite dimensional model is constructed and simulations carried out by using this model are able to capture the system dynamics, including the torsional responses observed during dry-friction whirling. Numerical results obtained by using this model are consistent with experimental observations. The findings of this study are relevant to whirling motions experienced by rotating, long flexible structures, such as drill strings used in oil-well explorations.

scholarly journals Fractional-order controllers for stick-slip vibration mitigation in oil well drill-strings

2021 ◽  
pp. 146134842098404
Author(s):  
Massinissa Derbal ◽  
Mohamed Gharib ◽  
Shady S Refaat ◽  
Alan Palazzolo ◽  
Sadok Sassi
Keyword(s):  
Fractional Order ◽  
Degrees Of Freedom ◽  
Lumped Parameter Model ◽  
Oil Well ◽  
Proportional Integral Derivative ◽  
Stick Slip ◽  
Proportional Integral ◽  
Drilling Performance ◽  
Weight On Bit ◽  
Rotary Speed

Drillstring–borehole interaction can produce severely damaging vibrations. An example is stick–slip vibration, which negatively affects drilling performance, tool integrity and completion time, and costs. Attempts to mitigate stick–slip vibration typically use passive means and/or change the operation parameters, such as weight on bit and rotational speed. Automating the latter approach, by means of feedback control, holds the promise of quicker and more effective mitigation. The present work presents three separate fractional-order controllers for mitigating drillstring slip–stick vibrations. For the sake of illustration, the drillstring is represented by a torsional vibration lumped parameter model with four degrees of freedom, including parameter uncertainty. The robustness of these fractional-order controllers is compared with traditional proportional-integral-derivative controllers under variation of the weight on bit and the drill bit’s desired rotary speed. The results confirm the proposed controllers effectiveness and feasibility, with rapid time response and less overshoot than conventional proportional-integral-derivative controllers.

Vibration and Dynamic Analysis of Oil Well Drillstring Considering Coupled Axial and Torsional Effects Using Cylindrical Superelement

2013 ◽  
Author(s):  
M. T. Ahmadian ◽  
Sh. Ghorbani ◽  
K. Firoozbakhsh ◽  
A. Barari
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Time History ◽  
Computer Time ◽  
Frictional Torque ◽  
Oil Well ◽  
Torsional Vibrations ◽  
Stick Slip ◽  
Slip Phenomenon ◽  
Element Method

In this paper axial and torsional vibrations of a drillstring are studied using cylindrical superelement. Drillstring vibration equation is derived by calculating kinetic and potential energy and work done by external forces on drillstring, and utilizing Hamilton’s principle. The model is analyzed by implementing finite element technique with consideration drillstring weight, centrifugal force due to rotation of drillstring, axial force resulting from bit with the formation contact and torsional torque caused by the stick-slip phenomenon. To calculate the vibrational response of drillstring, a computational finite element scheme was developed. For a typical case of oil well drillstring, the time response of axial and torsional vibrations of bit are presented. Also, time history of rotational speed of bit and frictional torque caused by the stick-slip phenomenon on bit, are calculated. Very good agreement is found between findings with implementing superelement and those were reported in the literature. The time consumption by conventional finite element method is very larger than implementing cylindrical superelement for the same problem. This indicates by implementing a few cylindrical superelements, the same results in much smaller computer time than the conventional finite element method, can be extracted.

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.

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.

Sign in / Sign up

Export Citation Format

Share Document