Mitigation of Stick-Slip Vibrations in Drilling Systems with Tuned Top Boundary Parameters

2020 ◽  
pp. 1-28
Author(s):  
Xianbo Liu ◽  
Zhao Zhang ◽  
Xie Zheng ◽  
Xinhua Long ◽  
Guang Meng

Abstract Aiming at preventing stick-slip oscillations in drilling systems for oil and gas explorations, a reduced-order model is proposed to capture the nonlinear torsional dynamics of drilling operations. In this model, the drill-string structure is simplified as a single-DOF system suffering from dry frictions at the drill bit, while the electromechanical boundary generated by the top-drive system is modeled as another tunable DOF used for stick-slip suppression. To simplify and parameterize the problems, a normalized 2-DOF system with negative damping and tunable parameters is deduced via nondimensionalization and linearization. Based on this system, stability criteria are obtained analytically in the 5-dimensional parametric space. Stable regions as well as the optimized boundary parameters are found analytically. The results suggest that the system can be stabilized by an optimally tuned boundary when and only when the magnitude of the negative damping is no greater than 2. It also reveals that the stability deteriorates if the inertia on the top is huge and non-adjustable, which is the commonest scenario for commercial drilling rigs nowadays. Finally, applications of the tuned boundary in a typical drilling system for stick-slip mitigation are conducted and verified numerically. The results indicate that the control performance can be potentially enhanced by three to five times, via an additional virtual negative inertia generated by the top-drive motor. This research provides an alternative approach to fully optimize the top boundary for curing stick-slip vibrations in drilling systems.

Author(s):  
Jialin Tian ◽  
Jie Wang ◽  
Siqi Zhou ◽  
Yinglin Yang ◽  
Liming Dai

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.


Author(s):  
Yeming Yao ◽  
Hua Zhou ◽  
Yinglong Chen ◽  
Huayong Yang

Counterbalance valves are widely used in hydraulic deck machinery to balance the overrunning loads. However, as is well known, counterbalance circuit designed with poor choice of counterbalance valve tends to introduce instability to the system. This paper investigates the dynamic behavior of a pilot operated counterbalance valve which can operate at a flow rate about 2000L/min. A linearized stability analysis of such a hydraulic circuit which consists of a slip in cartridge, a pilot counterbalance valve and a hydraulic winch is presented. Pole-zero plots are employed to reveal the effect of the volume of control cavity, the hydraulic resistance on pilot line and counterbalance valve pilot area ratio on the stability of the system. The analysis results indicate that such a system will be unstable within the normal range of each parameter. An alternative approach that guarantees system stability by adding an accumulator on the pilot line is put forward. The approach stabilizes the pilot pressure by reducing the hydro-stiffness of pilot control cavity, thus the system can reach its stability condition. Finally, a numerical optimization method is putted forward, with the optimized parameters, the dynamic performance of considered system become better.


2019 ◽  
Vol 300 ◽  
pp. 04004
Author(s):  
Edris Hassan ◽  
Jamil Abdo ◽  
Jan Kwak ◽  
Abdullah Al Shabibi

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.


2021 ◽  
Vol 143 (6) ◽  
Author(s):  
Sadok Sassi ◽  
Jamil Renno ◽  
Han Zhou ◽  
Amr Baz

Abstract During the drilling process in oil and gas fields, slender drill strings often experience a multitude of complex and simultaneous vibrational phenomena. Drill string vibrations hinder the drilling process and can cause premature wear and damage to the drilling equipment. Here, the suppression of drill string vibrations during drilling operations is experimentally investigated using a novel drill string design, based on the use of innovative periodic inserts that control the vibration transmissibility in different directions. These inserts are equipped with viscoelastic rings that act as sources of local resonances, surrounding piezoelectric actuators that generate internal axial loading when electrically excited. An experimental prototype that combined all these details was constructed and tested to demonstrate the periodic drill string's feasibility and effectiveness in minimizing undesirable vibrations. The obtained results indicate that the periodic inserts’ careful design can effectively enhance the drill strings’ dynamic behavior and conveniently regulate its bandgap characteristics. Both radial and axial vibrations were controlled, and the vibrations’ amplitude was reduced significantly over a wide range of frequencies. The proposed approach appears to present a viable means for designing intelligent drill strings with tunable bandgap characteristics.


Author(s):  
Parham Pournazari ◽  
Pradeepkumar Ashok ◽  
Eric van Oort

This paper presents a robust control algorithm for automatic hoisting of a drill string in oil and gas drilling operations. We demonstrate an iterative scheme for trajectory design and present a lumped dynamic model of the hoisting system. The trajectory is used along with the dynamic model to design a hybrid sliding mode and gain scheduled PI controller to deal with the frictional nonlinearities of the system. The simulation results demonstrate the feasibility of this approach in optimally performing the pipe hoisting task.


2018 ◽  
Vol 148 ◽  
pp. 16009 ◽  
Author(s):  
Leonardo D. Pereira ◽  
Bruno Cayres ◽  
Hans I. Weber

Part of the process of exploration and development of an oil field consists of the drilling operations for oil and gas wells. Particularly for deep water and ultra deep water wells, the operation requires the control of a very flexible structure which is subjected to complex boundary conditions such as the nonlinear interactions between drill bit and rock formation and between the drill string and borehole wall. Concerning this complexity, the stick-slip phenomenon is a major component related to the torsional vibration and it can excite both axial and lateral vibrations. With these intentions, this paper has the main goal of confronting the torsional vibration problem over a test rig numerical model using a real-time conventional controller. The system contains two discs in which dry friction torques are applied. Therefore, the dynamical behaviour were analysed with and without controlling strategies.


1991 ◽  
Vol 113 (1) ◽  
pp. 38-43 ◽  
Author(s):  
Yao-Qun Lin ◽  
Yu-Hwa Wang

The stick-slip vibration is introduced as a new mechanism to explain the large amplitude torsional oscillation of the drill strings in oil and gas well drillings. A record of field data is identified and simulated according to the new mechanism. The analytical results derived from the numerical simulation agree with the field data with 95.6 percent accuracy. The physical phenomenon of the stick-slip vibration of drill string is explained by initiating a phase trace in the phase plane. The beating phenomenon in drilling is interpreted in terms of stick-slip vibration. The effects of viscous damping, rotary speed and natural frequency on the stick-slip vibration are discussed.


2018 ◽  
Vol 148 ◽  
pp. 16005 ◽  
Author(s):  
Wei Lin ◽  
Yang Liu

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.


2004 ◽  
Vol 126 (4) ◽  
pp. 709-720 ◽  
Author(s):  
N. Mihajlovic´ ◽  
A. A. van Veggel ◽  
N. van de Wouw ◽  
H. Nijmeijer

In this paper, we aim for an improved understanding of the causes for torsional vibrations that appear in rotary drilling systems used for the exploration of oil and gas. For this purpose, an experimental drill-string setup is considered. In that system, torsional vibrations with and without stick-slip are observed in steady state. In order to obtain a predictive model, a discontinuous static friction model is proposed. The steady-state behavior of the drill-string system is analyzed both numerically and experimentally. A comparison of numerical and experimental bifurcation diagrams indicates the predictive quality of the model. Moreover, specific friction model characteristics can be linked to the existence of torsional vibrations with and without stick-slip.


Author(s):  
Manish Paliwal ◽  
Ajay Mahajan ◽  
Peter Filip

This paper presents a two degree of freedom (2-DOF) stick-slip friction model for studying the effect of contact stiffness on the stability of the system. It is shown that the stability is not only a function of non-linear variation in the friction force provide by stick-slip but also depends on the variation in stiffness of contact due to the formation of friction layers on the surface of the rotor and the brake pad. Parametric studies have been presented to show the effect of variation in coefficient of friction and contact stiffness on the system stability.


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