A New Dynamic Model of Coupled Axial–Torsional Vibration of a Drill String for Investigation on the Length Increment Effect on Stick–Slip Instability

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Ali Hosseinzadeh ◽  
Firooz Bakhtiari-Nejad
Keyword(s):  
Torsional Vibration ◽  
Angular Speed ◽  
Drill String ◽  
Body Motion ◽  
Depth Of Cut ◽  
Stick Slip ◽  
Input Parameters ◽  
Length Increment ◽  
Weight On Bit ◽  
Torque On Bit

In this paper, a new model is proposed to study the coupled axial–torsional vibration of the drill string. It is assumed that rotary table angular speed is constant and equals to the nominal angular speed of the drill string. In addition, axial displacement of any point on the drill string is considered to be as the sum of rigid-body motion and elastic vibrations. The depth of cut is defined using instantaneous dynamic states instead of using the delayed model as presented in previous researches. A velocity-weakening function is introduced for modeling the behavior of the frictional component of the torque-on-bit (TOB) with respect to the bit angular speed. After discretizing vibration equations, stability analysis of the system is investigated by linearizing the nonlinear system around its steady-state response point. Considering nominal weight-on-bit (WOB) (W0) and nominal rotational speed (Ω) as the input parameters of the drilling, variation of maximum allowable value of (W0) is presented with respect to variation of Ω . It is shown that the maximum allowable value of W0 has an increasing–decreasing behavior with respect to Ω. The effect of drill string upper and lower part lengths is studied on the stability of the system, and practical results are presented both in the condition that W0 is constant and in the condition that the hook upward force is constant. It is shown that by increasing the drill string length, the system is more exposed to instability, and this must be considered in regulating the input parameters of drilling.

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 Drilling Vibration Modes and Penetration Rate Modeling using Artificial Neural Network and Multiple Linear Regression Analysis in Khoman Formation at the Egyptian Western Desert

2021 ◽  
Author(s):  
Sherif A. Ezz ◽  
Mohamed S. Farahat ◽  
Said Kamel ◽  
Ahmed Z. Nouh
Keyword(s):  
Neural Network ◽  
Regression Analysis ◽  
Penetration Rate ◽  
Drill String ◽  
Western Desert ◽  
Circulation Rate ◽  
Vibration Level ◽  
Stick Slip ◽  
Weight On Bit ◽  
Rotary Speed

Abstract Drill string vibrations are one of the most serious problems encountered while drilling as the bit and drill string interaction with formations under certain drilling conditions usually induces complex shocks and vibrations into the drill string components resulting in premature failure of the equipment and reduced drilling penetration rate. In severe cases where shocks and vibrations accumulated into drill string till exceeded its maximum yield or torsional strength, fatigue will occur and thereby increase the field development costs associated with replacing damaged components, fishing jobs, lost-in-hole situations, and sidetracks. Thus, real-time monitoring for downhole generated vibrations and accordingly adjusting drilling parameters including weight on bit, rotary speed, and circulation rate play a vital role in reducing the severity of these undesirable conditions. Vibration optimization must be done incorporation with the penetration rate, as a minimum economical penetration rate is required by the operator. In this study, three penetration rate and vibration level models were developed for axial, lateral, and stick-slip drilling modes using both MATLAB™ Software neural network and multiple regression analysis. It is found that the three models' results for vibration level and penetration rate; as compared with those recorded drilling data; showed an excellent match within an acceptable error of average correlation coefficient (R) over 0.95. The prediction of penetration rate and vibration level is thoroughly investigated in different axial, lateral, and stick-slip vibration drilling modes to be able to best select the optimum safe drilling zone. It is found that the axial vibration could be dampened by gradually increasing the weight on bit and increasing rotary speed while both the lateral and torsional vibrations are enhanced by increasing the rotary speed and decreasing the weight on bit.

Analysis of stick-slip reduction for a new torsional vibration tool based on PID control

2019 ◽  
Vol 234 (1) ◽  
pp. 82-94 ◽  
Author(s):  
Jialin Tian ◽  
Yi Zhou ◽  
Lin Yang ◽  
Shuhui Hu
Keyword(s):  
Torsional Vibration ◽  
Pid Control ◽  
Control Method ◽  
Field Tests ◽  
Rock Breaking ◽  
Drill String ◽  
Viscosity Reduction ◽  
Stick Slip ◽  
Deep Wells ◽  
Reduction Characteristics

The phenomenon of stick-slip vibration is widespread in the exploration of deep and ultra-deep wells. It causes the reduction of the mechanical drilling rate and wastes the driving energy. Besides, it also accelerates the aging and failure of the drill strings and threatens the safety of drilling seriously. In order to effectively control the stick-slip vibration of the drill string, a new type of torsional vibration tool is proposed in this paper firstly. Then, the theoretical model of the drill string system based on the tool is established. And then, the viscosity reduction characteristics of the new torsional vibration tool are studied by the PID control method. Finally, field tests were carried out in comparison with simulation. The results show that the new torsional vibration tool can reduce the stick-slip vibration. And the two PID control equations can both control the drill bit speed in real time through changing the turntable speed. The results also have important reference significance for reducing and controlling the stick-slip vibration of the drill string and improving the rock-breaking efficiency.

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.

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.

Effects of weight on bit on torsional stick-slip vibration of oilwell drill string

2017 ◽  
Vol 31 (10) ◽  
pp. 4589-4597 ◽  
Author(s):  
Liping Tang ◽  
Xiaohua Zhu ◽  
Xudong Qian ◽  
Changshuai Shi
Keyword(s):  
Drill String ◽  
Stick Slip ◽  
Weight On Bit

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]

Drilling System Optimization Leads to Expedited Wells Delivery

2021 ◽  
Author(s):  
Efe Mulumba Ovwigho ◽  
Saleh Al Marri ◽  
Abdulaziz Al Hajri
Keyword(s):  
Drill Pipe ◽  
System Optimization ◽  
Drill String ◽  
Stick Slip ◽  
Drilling Performance ◽  
Drilling Parameters ◽  
Single String ◽  
Innovative Solution ◽  
Open Hole ◽  
Weight On Bit

Abstract On a Deep Gas Project in the Middle East, it is required to drill 3500 ft of 8-3/8" deviated section and land the well across highly interbedded and abrasive sandstone formations with compressive strength of 15 - 35 kpsi. While drilling this section, the drill string was constantly stalling and as such could not optimize drilling parameters. Due to the resulting low ROP, it was necessary to optimize the Drill string in order to enhance performance. Performed dynamic BHA modelling which showed current drill string was not optimized for drilling long curved sections. Simulation showed high buckling levels across the 4" drill pipe and not all the weight applied on surface was transmitted to the bit. The drilling torque, flowrate and standpipe pressures were limited by the 4" drill pipe. This impacted the ROP and overall drilling performance. Proposed to replace the 4" drill pipe with 5-1/2" drill pipe. Ran the simulations and the model predicted improved drill string stability, better transmission of weights to the bit and increased ROP. One well was assigned for the implementation. Ran the optimized BHA solution, able to apply the maximum surface weight on bit recommended by the bit manufacturer, while drilling did not observe string stalling or erratic torque. There was also low levels of shocks and vibrations and stick-slip. Doubled the on-bottom ROP while drilling this section with the same bit. Unlike wells drilled with the previous BHA, on this run, observed high BHA stability while drilling, hole was in great shape while POOH to the shoe after drilling the section, there were no tight spots recorded while tripping and this resulted in the elimination of the planned wiper trip. Decision taken to perform open hole logging operation on cable and subsequently run 7-in liner without performing a reaming trip. This BHA has been adopted on the Project and subsequent wells drilled with this single string showed similar performance. This solution has led to average savings of approximately 120 hours per well drilled subsequently on this field. This consist of 80 hours due to improved ROP, 10 hrs due to the elimination of wiper trip and a further 30 hrs from optimized logging operation on cable. In addition, wells are now delivered earlier due to this innovative solution. This paper will show how simple changes in drill string design can lead to huge savings in this current climate where there is a constant push for reduction in well times, well costs and improved well delivery. It will explain the step-by-step process that was followed prior to implementing this innovative solution.

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