Nonlinear Modeling and Qualitative Analysis of Coupled Vibrations in a Drill String

2018 ◽  
Vol 28 (10) ◽  
pp. 1850119
Author(s):  
Fushen Ren ◽  
Baojin Wang ◽  
Suli Chen
Keyword(s):  
Qualitative Analysis ◽  
Nonlinear Modeling ◽  
Coupled Model ◽  
Axial Rotation ◽  
Drill String ◽  
Coupled Vibration ◽  
Lateral Vibrations ◽  
Axial Excitation ◽  
Torsional Excitation ◽  
Runge Kutta

A coupled model for axial/torsional/lateral vibrations of the drill string is presented, in which the nonlinear dynamics and qualitative analysis method are employed to find out the key factors and sensitive zone for coupled vibration. The drill string is simplified as an equivalent shell under axial rotation. After dimensionless processing, the mathematical model for coupled axial/torsional/lateral vibrations of the drill string is obtained. The Runge–Kutta–Fehlberg method is employed for the numerical simulation, and the rules that govern the changing of the torsional and axial excitation are revealed. And the stability domains of the explicit Runge–Kutta method are analyzed. Furthermore, the suggestions for field applications are also presented. It is demonstrated by simulation results that the lateral/axial/torsional vibrations exist simultaneously and couple with each other. The system will obtain a stable period motion with an axial excitation zone before the coupled vibration in the three directions, and continue to increase the axial excitation to cause the coupled vibration easily. The torsional excitation of the drill string mainly contributes to the coupled vibration in the three directions when in a specific rotation speed zone. The system is more likely to obtain a periodic motion through adjusting the torsional excitation out of this zone.

Finite Element Analysis on Axial-Torsional Coupled Vibration of Drill String

2011 ◽  
Vol 291-294 ◽  
pp. 1952-1956 ◽  
Author(s):  
Xue Liang Bi ◽  
Jian Wang ◽  
Zhan Lin Wang ◽  
Shi Hui Sun
Keyword(s):  
Finite Element ◽  
Coupled Model ◽  
Resonance State ◽  
Drill String ◽  
Hole Drilling ◽  
Drilling Process ◽  
Coupled Vibration ◽  
Element Analysis ◽  
Drilling String ◽  
Rotary Speed

In the drilling process, axial vibration, transverse vibration and torsional vibration happen to drilling string. And the coupled vibration is more complex. In the resonance state, drilling string collides with the wall, which causes serious damage on drilling string in a short time and results in economic loss to the drilling operation. In this paper, the regularity of coupled vibration is analyzed by using finite element method. The model of full-hole drilling strings is established. The distribution regularities of coupled resonant frequency are obtained through computer analysis. The coupled model is more accurate than single vibration model. And the gaps of high rotary speed resonance regions are larger. Resonance state can be avoided by changing rotary speed, and drilling accidents can be reduced.

scholarly journals Nonlinear Model and Qualitative Analysis for Coupled Axial/Torsional Vibrations of Drill String

2016 ◽  
Vol 2016 ◽  
pp. 1-17 ◽  
Author(s):  
Fushen Ren ◽  
Baojin Wang ◽  
Suli Chen ◽  
Zhigang Yao ◽  
Baojun Bai
Keyword(s):  
Nonlinear Dynamics ◽  
Qualitative Analysis ◽  
Axial Stress ◽  
Drill String ◽  
Torsional Vibrations ◽  
Flexible Shell ◽  
Coupling Vibration ◽  
Axial Excitation ◽  
Key Factor ◽  
Analysis Of Dynamics

A nonlinear dynamics model and qualitative analysis are presented to study the key effective factors for coupled axial/torsional vibrations of a drill string, which is described as a simplified, equivalent, flexible shell under axial rotation. Here, after dimensionless processing, the mathematical models are obtained accounting for the coupling of axial and torsional vibrations using the nonlinear dynamics qualitative method, in which excitation loads and boundary conditions of the drill string are simplified to a rotating, flexible shell. The analysis of dynamics responses is performed by means of the Runge-Kutta-Fehlberg method, in which the rules that govern the changing of the torsional and axial excitation are revealed, and suggestions for engineering applications are also given. The simulation analysis shows that when the drill string is in a lower-speed rotation zone, the torsional excitation is the key factor in the coupling vibration, and increasing the torsional stress of the drill string more easily leads to the coupling vibration; however, when the drill string is in a higher-speed rotating zone, the axial excitation is a key factor in the coupling vibration, and the axial stress in a particular interval more easily leads to the coupling vibration of the drill string.

Application of the piecewise constant method in nonlinear dynamics of drill string

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jialin Tian ◽  
Jie Wang ◽  
Yi Zhou ◽  
Lin Yang ◽  
Changyue Fan ◽  
...  
Keyword(s):  
Nonlinear Dynamics ◽  
Dynamic Model ◽  
Dynamic Characteristics ◽  
Drill String ◽  
Vibration Velocity ◽  
Kutta Method ◽  
Time Step ◽  
Piecewise Constant ◽  
Runge Kutta Method ◽  
Runge Kutta

Abstract Aiming at the current development of drilling technology and the deepening of oil and gas exploration, we focus on better studying the nonlinear dynamic characteristics of the drill string under complex working conditions and knowing the real movement of the drill string during drilling. This paper firstly combines the actual situation of the well to establish the dynamic model of the horizontal drill string, and analyzes the dynamic characteristics, giving the expression of the force of each part of the model. Secondly, it introduces the piecewise constant method (simply known as PT method), and gives the solution equation. Then according to the basic parameters, the axial vibration displacement and vibration velocity at the test points are solved by the PT method and the Runge–Kutta method, respectively, and the phase diagram, the Poincare map, and the spectrogram are obtained. The results obtained by the two methods are compared and analyzed. Finally, the relevant experimental tests are carried out. It shows that the results of the dynamic model of the horizontal drill string are basically consistent with the results obtained by the actual test, which verifies the validity of the dynamic model and the correctness of the calculated results. When solving the drill string nonlinear dynamics, the results of the PT method is closer to the theoretical solution than that of the Runge–Kutta method with the same order and time step. And the PT method is better than the Runge–Kutta method with the same order in smoothness and continuity in solving the drill string nonlinear dynamics.

scholarly journals Dynamic Behavior of Geared Rotors

1997 ◽  
Author(s):  
T. N. Shiau ◽  
J. S. Rao ◽  
J. R. Chang ◽  
Siu-Tong Choi
Keyword(s):  
Dynamic Behavior ◽  
Chaotic Behavior ◽  
Squeeze Film ◽  
Rotor Systems ◽  
Lateral Vibrations ◽  
Squeeze Film Dampers ◽  
Torsional Excitation ◽  
Route To Chaos

This paper is concerned with the dynamic behavior of geared rotor systems supported by squeeze film dampers, wherein coupled bending torsion vibrations occur. Considering the imbalance forces and gravity, it is shown that geared rotors exhibit chaotic behavior due to non linearity of damper forces. The route to chaos in such systems is established. In geared rotor systems, it is shown that torsional excitation can induce lateral vibrations. It is shown that squeeze film dampers can suppress large amplitudes of whirl arising out of torsional excitation.

scholarly journals Dynamic Model and Quantitative Analysis of Stick-Slip Vibration in Horizontal Well

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Baojin Wang ◽  
Zhongyang Wang ◽  
Fushen Ren
Keyword(s):  
Angular Velocity ◽  
Horizontal Well ◽  
Angular Speed ◽  
Stick Slip ◽  
Rock Interaction ◽  
Axial Excitation ◽  
Nonlinear Motion ◽  
Fluctuation Amplitude ◽  
Torsional Excitation ◽  
Observation Results

Stick-slip is very harmful to the service life of drillstring. The extended Hamilton principle is applied in the paper. Then, finite element method (FEM) is employed to describe the model. The drillstring-borehole impact and friction, fluid-structure interaction, bit-rock interaction, and gravity are considered in this model. The influence of axial and torsional excitation on stick-slip is analyzed. The nonlinear motion predicted by the model is consistent with the observation results in the experiments. The research shows that the fluctuation amplitude of the bit angular velocity also increases along with the increase of driving angular velocity (torsional excitation). However, both the ratio of the maximum angular velocity of the stick-slip vibration and the fluctuation of the angular velocity are continuously reduced. Meanwhile, the strength of the stick-slip vibration has a tendency to slow down. As the axial load (axial excitation) increases, the fluctuation of the maximum angular speed of the stick-slip vibration does not change significantly, but the smaller load causes a smaller stick duration.

Torsional Vibration, in Rotordynamic System, Identified by Monitoring Gearbox Behaviour

2008 ◽  
Author(s):  
Lorenzo Naldi ◽  
Roberto Biondi ◽  
Valerio Rossi
Keyword(s):  
Power Generation ◽  
Strain Gage ◽  
Measurement System ◽  
Torsional Vibration ◽  
Electrical Machines ◽  
Post Processing ◽  
Optical Probes ◽  
Lateral Vibrations ◽  
Torsional Excitation ◽  
Standard Instrumentation

Nowadays the wide diffusion of the electrical machines, used for power generation, or as driver/helper in Oil&Gas applications, have amplified the problematic related to train torsional excitation. The standard instrumentation installed on the train does not permit to monitor and analyze this kind of stress; therefore to define criteria to screen torsional alternating stress by lateral vibrations becomes extremely important. This paper describes the experience achieved by the authors in the study of rotordynamic behavior of some geared train with the goal to define a methodology to analyze torsional stresses adopting industrial proximity probes (installed in the gear) or a non intrusive measurement system (optical probes). In order to confirm the last technology, an additional classic strain gage torsional measurement has been adopted obtaining similar results. An extensive part of this paper is dedicated to illustrate several test campaigns performed in different site where customers highlighted abnormal vibration levels. Finally, a wide description of data post processing and consequent conclusions are offered.

Qualitative Analysis of Drill String Torsional Vibration Preventive Measures: Present Status and Future Possible Solution

2016 ◽  
Author(s):  
Arash Asgharzadeh ◽  
Opeyemi Bello ◽  
Nelson Rafael Perozo Baptista ◽  
Carlos Andres Paz Carvajal ◽  
Javier Holzmann Berdasco ◽  
...  
Keyword(s):  
Qualitative Analysis ◽  
Torsional Vibration ◽  
Present Status ◽  
Preventive Measures ◽  
Drill String

scholarly journals Numerical Application of a Stick-Slip Control and Experimental Analysis using a Test Rig

2018 ◽  
Vol 148 ◽  
pp. 16009 ◽  
Author(s):  
Leonardo D. Pereira ◽  
Bruno Cayres ◽  
Hans I. Weber
Keyword(s):  
Deep Water ◽  
Torsional Vibration ◽  
Oil And Gas ◽  
Dynamical Behaviour ◽  
Drill String ◽  
Oil Field ◽  
Test Rig ◽  
Numerical Application ◽  
Stick Slip ◽  
Lateral Vibrations

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.

Field Verification of Model-Derived Natural Frequencies of a Drill String

2002 ◽  
Vol 124 (3) ◽  
pp. 154-162 ◽  
Author(s):  
Pushkar N. Jogi ◽  
John D. Macpherson ◽  
Michael Neubert
Keyword(s):  
Natural Frequencies ◽  
Drill String ◽  
Vibration Measurement ◽  
Premature Failure ◽  
Lateral Vibrations ◽  
Axial Acceleration ◽  
Weight On Bit ◽  
Measurement While Drilling ◽  
Actual Field ◽  
Downhole Measurements

Vibrations generated in a drill string while drilling generally lead to a reduction in drilling efficiency and often cause premature failure of drill string components and bit damage. It is also known that lateral vibrations, in particular, are responsible for most measurement-while-drilling (MWD) tool failures while drilling. One way to increase drilling efficiency and avoid tool damage is to monitor and analyze drilling vibrations so that drilling parameters can be adjusted while drilling to reduce such vibrations. An alternative method is to analyze and determine the natural frequencies of the bottom-hole assembly (BHA) so that resonant conditions caused by various excitation mechanisms in the drill string can be avoided. Even though models have been developed in the past in the drilling industry to determine the natural frequencies of a BHA, few attempts have been made to demonstrate that such models do actually help reduce vibrations or failures. This paper deals with the process of field validation of model-derived frequencies for axial, torsional and lateral vibrations. The results presented in this paper are based on the analysis of drilling data from a field test using downhole vibration measurement sensors. The downhole measurements included X and Y bending moments, axial acceleration, dynamic weight-on-bit, dynamic torque, and X and Y-axis magnetometers mounted in an MWD sub. The data analysis demonstrates that the natural frequencies predicted by the models match well with actual field (measured) values at the locations of interest, particularly for lateral vibrations. This analysis therefore shows that model derived results can be used with a degree of confidence to help avoid resonant conditions in a BHA while drilling and to help reduce failures.

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