Drill String Vibration Research Articles

The Review and Development of Devices with an Increasing Rate of Penetration (ROP) in Deep Formation Drilling Based on Drill String Vibration

The oil and gas resources stored in deep strata are an important replacement field of the petroleum industry. Accelerating the exploration and development of deep oil and gas is of great significance to the security of energy strategy. Drilling is the primary link and necessary means of deep oil and gas exploration and development. Slow drilling speed is one of the key problems restricting the exploration and development of deep oil and gas. The research and development of down-hole equipment with an increasing ROP provides a technical means for increasing the ROP. However, the energy of existing down-hole equipment with an increasing ROP comes from the drilling circulation medium, and the ROP increase effect of such equipment is relatively obvious in shallow and middle formations. However, with the increase in well depth, energy in the circulation medium increasingly struggles to reach deeper formations, and the ROP increase effect is not good at the later stage of drilling. In the drilling process, drill string vibration is a frequently encountered complex situation, but it also contains sufficient energy, and the energy of drill string vibration will increase with an increase in the well depth, which can meet the energy demand of increasing the ROP in deep oil and gas exploration. This paper analyzes the characteristics of drill string vibration, and introduces six kinds of devices that take drill string vibration as energy and realize drill string vibration reduction, bottom-hole pressurization, and high-pressure pulse jet, providing a new idea for the development of deep down-hole speed-increasing devices.

Pattern recognition of stick-slip vibration in combined signals of DrillString vibration

Vibration signal measurement is one of the important methods to study the movement mode of the drill string. Through the interpretation of the vibration signal, the vibration pattern of the drill string can be accurately identified. MWD is a measurement method which can more directly reflect the vibration information of the drill string. In this paper, firstly, the drill string vibration signal is obtained by the sensors with a three-axis accelerometer and a gyroscope, and the sensor’s response has been solved and analyzed, which proves the effectiveness of this method for expressing drill string vibration information and the correlation between the measured signals. Then, the correlation coefficient, as the characteristic information basing on signal combination, is proposed; since the correlation coefficients of different patterns have different distribution characteristics, supervised machine learning is used to establish a classification model of vibration patterns. Finally, through the application of classification model in the actual drill data, the specific vibration types of various modes are clarified, which proves that the classification model can effectively distinguish different vibration modes and its accuracy can reach up to 95%.

Investigation into the effect of friction decay factor on the modelling and attenuation of stick-slip vibrations of oilwell drilling systems

The self-excited stick-slip oscillations of oilwell drillstrings are attributed to the nonlinear interaction between the drill-bit and the rock formation. Development of more accurate models will lead to improved predictions allowing more potential for successful suppression of the drillstring vibrations, thus reducing damage to the drilling system, prevention of expensive failures and increased output from the oilwell. In this paper, the effect of the transition from static friction to Coulomb friction on modelling of stick-slip phenomenon of oil well drill string is investigated through an analysis of the so called ‘decay factor’. Based on a distributed-lumped parameter model (DLPM) of the drilling system, the governing equations of motion for the system are obtained. By using different values of decay factor (low, high and medium), the stick-slip vibrations of the drill string are validated against published data from full-scale drill strings. The results from the simulation show that lowering the decay factor increases the critical speed and thus reduces the propensity for stick slip motion. However, a reduction in the decay factor also has the effect of inducing worse stick-slip motion once the critical speed has been reached. The results indicate the wider impact of both correct modelling of the decay factor, but also the importance of correct characterisation of the mud viscosity and drill/well contact for more accurate selection of drilling parameters in the field.

Analysis of Drill-String Nonlinear Dynamics Using the Lumped-Parameter Method

This work aims at studying the nonlinear dynamics of drill strings using the lumped-parameter method (LPM). The study is based on the good consistency of the results of the test problem where the model of the longitudinal vibrations of a horizontal drill string with a static compressive load at the left end is considered. In this paper, this method is applied to discretize linear and nonlinear models of the lateral vibrations of a vertical drill string under the effect of a supersonic gas flow. The obtained results are verified with the previously published data. The optimal number of the drill-string partitions is determined using the developed application, which allows us to estimate the accuracy of the loaded data. The numerical solution of the model is obtained using the fourth-order Runge–Kutta method. The optimization of the numerical algorithm using parallel-programming tools is carried out, and the efficiency of the method is analyzed.

Investigating Drillstring Vibration and Stability in Coring Drilling

Transverse vibration of drillpipe in coring drilling is undesirable. Here, the influence of the core on drillpipe vibration is considered for the first time. Attention is focused on the vibrations of the coring drillpipe as these vibrations lead to contact and collision between drillpipe and core. A reduced-order model of drill string motion is established considering fluid load and core constraints. This model considers fluid action as distributed load and drillpipe as beam structure. The constraint of the core on lateral vibration of the drillpipe is simplified as a nonlinear force. The method of multiple scales is used to analyze the disturbance of the drillpipe’s primary resonance and harmonic resonance, and the influence law of different parameters on the drillpipe resonance is obtained. The results show that damping inhibits resonance vibration, and external excitation determines the resonance type. The existence of the core will aggravate the resonance vibration of the drillpipe. The analysis results are helpful in understanding the resonance of the drillpipe in coring drilling. Some measures to suppress resonance are given in this paper. This study can provide guidance for further research on drillpipe resonance in core drilling.

Nonlinear vibrations of composite drill strings considering drill string–wellbore contact and bit–rock interaction

Nonlinear vibrations of composite drill strings considering drill string–wellbore contact and bit–rock interaction

Application of the lumped-parameter method for modeling nonlinear vibrations of drill strings with stabilizers in a supersonic gas flow

In this paper, we study the nonlinear dynamics of a drill string under the effect of external loads in a supersonic gas flow, taking into account supporting stabilizers. The case of the drill string spatial lateral vibrations, which are the main cause of the drilling equipment failures, is considered. To account for nonlinear effects, a mathematical model based on the general relations of Novozhilov's nonlinear theory of elasticity is developed. The discretization of the model is conducted using the lumped-parameter method. The explicit fourth order Runge-Kutta method is utilized for obtaining a numerical solution for the studied system. The effect of damping elements (supporting stabilizers) on the drill string lateral vibrations is analyzed. Numerical illustrations are presented, and the corresponding recommendations for deep and shallow drilling are given.

Modelling and controlling of drill string stick slip vibrations in an oil well drilling rig

Mitigating of drill string vibrations, plays a distinctive role in increase of rate of penetration and consequently decrease of the operation costs, prevent of severe damages to drill string and bit, increase of drilling operation quality and safety, and enhance the performances of the controllers. This study deals with modelling and controlling of drill string vibrations with focus on stick slip vibrations in vertical wells. The approach taken to sub-divide the drill string into smaller torsional sections and model the complete system dynamically and employ the extracted torsional model to model the stick slip vibrations mathematically. To mitigate and or active control of stick slip vibrations, three architectures are developed and proposed, manipulation of the rotational speed, manipulation of the weight on bit, and increasing of the damping in the bottom of the drill string. The performance of each strategy is analysed individually as well as relative to each other, using a mathematical measure when the drill string length is divided into smaller torsional sections. By the aid of the simulations and mathematical measures, it is shown that manipulation of rotational speeds at the surface may not be an effective solution to reduce the stick slip vibrations, however manipulation of weight on bit and increasing of damping at the bottom of string can be two effective solutions to mitigate these kinds of vibrations. As a general conclusion, it is proved that the manipulation of bottom side drilling parameters is more effective than the manipulation of surface drilling parameters.

Nonlinear analysis of axial-torsional vibration of drill string based on a 3 DOF model

Based on a model with three-degree-of-freedom, the nonlinear coupled axial-torsional vibration of drill string is numerically studied considering a modified contact model of bit-rock interaction. The effects of driving angular velocities, nominal drilling pressures, and formation stiffness on response are discussed. The simulation results show that response can be periodic, quasi-periodic or chaotic motion with the variation of system parameters. Increasing driving angular velocity is helpful to reduce the duration of sticking and even make the system stick-slip free. However, bit-bounce may occur if driving angular velocity is too large. Increasing nominal drilling pressure can cause the system to be more prone to stick-slip, but it has dampening effect on bit-bounce. The larger the formation stiffness is, the smaller the amplitude of the axial vibration response of the system is, and the driving angular velocity corresponding to the maximum amplitude of the axial vibration response is also larger, whereas the variation of the amplitude of torsional vibration is smaller. Compared with the results from two-degree-of-freedom model, the amplitude of torsional vibration of the present model is remarkable greater. Meanwhile, the present model is more prone to stick-slip than the one with two-degree-of-freedom, and it is not easy to bit bounce.

Non-Linear Vibrations of Composite Drill Strings–Wellbore Contact Considering Dynamics of Them at the Contact Zones

Non-Linear Vibrations of Composite Drill Strings–Wellbore Contact Considering Dynamics of Them at the Contact Zones

An Alternative Formulation for Modeling Self-Excited Vibrations of Drillstring With Polycrystalline Diamond Compact Bits

Abstract This work describes an alternative formulation of a system of nonlinear state-dependent delay differential equations (SDDDEs), which governs the coupled axial-torsional vibrations of a 2 DOF drillstring model with a realistic representation of polycrystalline diamond compact (PDC) bits. The regenerative effect associated with the complex cutter layout for such bits can introduce up to 100 state-dependent delays in the equations of motion. This large number of state-dependent delays renders the computational efficiency of conventional solution strategies unacceptable. The regeneration of the bottom-hole surface can alternatively be described by the bit trajectory function, whose evolution is governed by a partial differential equation (PDE). Thus the original system of SDDDEs can be replaced by a nonlinear coupled system of a PDE and ordinary differential equations (ODEs). Via the application of the Galerkin Method, this system of PDE-ODEs is transformed into a system of coupled ODEs, which can readily be solved. The algorithm is further extended to perform a linear stability analysis of the bit motion. The resulting stability boundaries are verified with time-domain simulations. The reported algorithm could, in principle, be applied to a more realistic drillstring model, which may lead to an in-depth understanding of the mitigation of self-excited vibrations through PDC bit designs.

The vibration harmonic response analysis of drillstring in compound drilling

The harmonic response analysis model of drillstring is established to improve borehole quality. The harmonic response laws of drillstring is discussed. Harmonic response analysis is made intensively for longitudinal vibration, including non-failure case and failure case. Position of the maximum response displacement of drillstring and the maximum response stress at corresponding position are obtained through harmonic response analysis. Absorber control measure is simulated to lower vibration amplitude of drillstring. New suggestions are put forward from the view of controlling drillstring vibration by comparing and classifying features of vibration control measures comprehensively. In course of designing drilling parameter, it is required to avoid or reduce drillstring resonance under low-order inherent frequency as much as possible and adopt targeted comprehensive control measures timely. The research result is of much significance to improve wellbore quality.

Investigation of the cutting force response to a PDC cutter in rock using the discrete element method

In the drilling industry, Polycrystalline Diamond Compact (PDC) bits with multiple fixed PDC cutters are widely applied to cut rock under high bottom hole pressure and high temperature. The bit-rock interaction is the main excitation source of drill string vibrations and needs to be understood and controlled better to improve the performance of the drilling process. Rock cutting mechanisms can be examined best for a single PDC cutter: Limitations of dynamic control and available sensors in experimental setups are eliminated in numerical simulations. Using the Discrete Element Method (DEM), deformation and strength of rock can be modeled through its full degradation in the PDC cutting process under typical environmental conditions. Stresses and strains in the rock material and on the cutter faces become available for examination.In this paper, numerical simulations of the cutting process are conducted using a modified bonded-particle model (specialized DEM), which is calibrated to a pressure series of high-strain triaxial laboratory tests. The simulation results are interpreted from the perspective of continuum mechanics providing stress and strain rate fields within the rock. These serve to identify two primary deformation modes predominant in two distinct zones moving with the PDC cutter: A crush zone below the chamfer and a shear zone ahead of the cutter face. The influences of two cutter design parameters, the back rake angle and the chamfer size, on these zones and the cutting force, are investigated. The shear angle is found to decrease with increasing back rake angle, resulting in a wider shear band. Moreover, the back rake angle has a considerable influence on the cutting forces both in the normal and tangential direction, whereas the chamfer size affects the normal cutting force predominantly. These results are in good accordance with experimental observations in the literature. Furthermore, the relationship between the cutting force and underlying rock failure mechanisms is clarified.This study enhances the understanding of the rock cutting process and gives first indications for dynamic cutting force control through cutter design.

Nonlinear dynamic characteristics of the drill-string for deep-water and ultra-deep water drilling

Riser will bend and deform in deep-water and ultra-deep water drilling, which may affect the dynamic characteristics of the drill-string. The analysis of drill-string dynamic characteristics is very difficult due to its super slenderness ratio. As the drill-string rotates in a curved narrow wellbore, the geometric nonlinearity and contact nonlinearity must be considered. In this study, a new method is proposed to analyze the drill-string dynamics considering the influence of riser deformation. The configuration of riser, based on different sea current velocities, is calculated to form a quasi-dynamic well trajectory combining with the fixed wellbore under mudline. In order to solve the dynamic problem of an extra-long drill-string model, the node iteration method is used to judge whether contact occurs at each node, and the Newmark method is used to calculate the spatial configuration of the drill-string at each time step. A program is successfully developed to analyze the dynamic characteristics of the drill-string in a deformed riser. The simulation results show that the deformation of the riser caused by ocean current has a great influence on the lateral vibration of the upper drill-string, and relatively little effect on the bottom-hole assembly. The contact and collision force near subsea wellhead is so large that may result in eccentric wear and leakage of the nearby riser.

Self-Powered Downhole Drilling Tools Vibration Sensor Based on Triboelectric Nanogenerator

The vibration state of the drilling tool is particularly important for its working condition monitoring. Here, a self-powered downhole drilling tools vibration sensor (hereafter referred to as V-TENG) based on triboelectric nanogenerator (TENG) is proposed. The V-TENG, which is designed as the single electrode and independent layer TENG, can synchronously realize the measurement of drilling tools vibration frequency and amplitude. Test results show that the frequency measuring range is 0 to 13 Hz, with an error of no more than 5%, and the amplitude measuring range is 0 to 130 mm, with a resolution of 10 mm and a maximum deviation of 5 mm. In addition, the possibility of the sensor converting vibration energy into electrical energy and providing power for other measuring instruments was explored, the test results show that the maximum power of the frequency measuring module is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$88.92\times 10$ </tex-math></inline-formula> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−8</sup> W with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{8} {\boldsymbol \Omega } $ </tex-math></inline-formula> resistance in series, while the amplitude measurement is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$28.62\times 10$ </tex-math></inline-formula> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−9</sup> W with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{9} {\boldsymbol \Omega }$ </tex-math></inline-formula> resistance in series. Compared with traditional downhole vibration sensors, the V-TENG can synchronously measure the drill string vibration frequency and amplitude in a self-powered model, which is more suitable for downhole conditions.

A rotor dynamics modal vibrational analysis of a water well rig drill string

Drill String (DS) vibrations are excessive and cause early failure of various parts of the drill string due to fatigue. A drill string is a part of the rig bottom that consists of drill pipe, a drill collar, and a bit. The more the drill pipes are connected, the longer the drill string. The phenomenon caused by drill string vibrations can be avoided by stopping the drill string to rotate or move at its natural frequency, or, in other words, to avoid resonance. Rotational Speed (RS) in the drill string causes lateral vibrations and stick-slip in torsional vibrations. This research investigates vibration under the action of parameters such as water well drill string lengths and rotational speeds. A drill string was finite element modelled in the Analysis of Systems (ANSYS) workbench 2020, mechanical. The Campbell diagram was used to analyze critical speeds, Backward Whirl (BW), and Forward Whirl (FW) and drill string length.

An Improved Model to Characterize Drill-String Vibrations in Rotary Drilling Applications

A specific model is elaborated for stick-slip and bit-bounce vibrations, which are dangerous dynamic phenomena typically encountered in the context of rotary drilling applications. Such a model takes into account two coupled degrees of freedom of drill-string vibrations. Moreover, it assumes a state-dependent time delay and a viscous damping for both the axial and torsional vibrations and relies on a sawtooth function to account for the cutting force fluctuation. In the frame of this theoretical approach, the influence of rock brittleness on the stability of the drill string is calculated via direct integration of the model equations. The results show that the rock brittleness has a great influence on the rotational speed and bit depth.

Modeling and analysis of torsional vibrations in borehole drill strings

Bore hole drilling is a growing activity driven by the need to access important resources like ground water and fossil fuels. In the process, however, undesired vibrations and shocks on the drill strings are invariably experienced, and this has a detrimental impact on the equipment. To get a full understanding of the origins and characteristics of this dysfunction, a generalized lumped-parameter model of the drill string system is studied to provide a deeper understanding of the drillstring dynamics and bit mechanics. The torsional stick-slip vibration phenomenon focuses on analyzing the source of vibration excitation, which is primarily the nonlinear bit-rock fictional interaction. The impact of various parameters such as the weight on the bit, rotational speed, and damping on the severity of vibration, in particular stick-slip vibration, is further analyzed. The simulation results highlight the significance of the key factors for stick-slip onset and severity. These controllable factors can be used to eliminate stick-slip while avoiding other undesirable effects, achieving optimum performance. Further research will be done on multi-stability analysis to define the optimum operation zones and design of vibration reduction tools and control strategies.

3D numerical modeling of the effect of the drill string vibration cyclic loads on the wellbore natural fracture growth

The maintenance of wellbore stability remains one of the major sources of Non-Productive Time in the oil industry. During drilling process, the drill string vibration cyclic loads which are applied on the wellbore progressively affect the initial parameters of the fractured formation (such as its length and width), finally resulting into wellbore instability. In this research, a three-dimensional poro elasto plastic finite element model was built using a non-linear finite element software ABAQUS purposely to investigate the effect of drill string vibration cyclic loads on the wellbore natural fracture growth. The main conclusions exhibited that the dependency of the fracture width profiles with the time followed an oscillating comportment analogous to the vibration cyclic loads profiles. For distinct cyclic load magnitudes and constant number of cyclic loads, the biggest percentage augmentation of the fracture width after integration of cyclic loads was 64.77%. Interestingly, the aperture of the fracture increased with the length of the fracture in the region neighboring the wellbore while it globally declined when going farther aside the wellbore. But for constant magnitude of cyclic load and distinct cyclic loads number, the highest rate of fracture aperture augmentation after incorporation of cyclic loads was moderately smaller representing 63.12% while the sinusoidal period of the fracture aperture grew with the number of cyclic loads number. The alternate studies demonstrated that the vibration cyclic loads were approximately unrelated to the fracture length development and the bottom hole pressure evolution. However, the fracture aperture and the loss circulation rate were significantly influenced by the vibration and the biggest percentage augmentation of the loss circulation rate after implementation of cyclic loads was 14.3%. This study broadens the understanding of the coupling between the drill string vibration cyclic loads and the wellbore natural fracture rock development which is a thematic that has been seldom examined in the literature.

Measurement and Analysis of Downhole Drill String Vibration Signal

Downhole drill string vibration data can provide an effective reference for research drill string vibration during drilling. In this paper, the research group used a storage-type downhole vibration measurement equipment equipped with an orthogonal, three-axis accelerometer to measure and collect drill string vibration signals during drilling in an oil well. Based on the installation characteristics of the sensor, the relationship between the acceleration measurement value of the sensor and the center acceleration value of the drill string is obtained. Then the time-domain signals representative of the vibration in igneous rock drilling is analyzed. It can be found that the occurrence of stick-slip vibration can be judged by the regular wave packets in the time-domain signal, while the time-domain signal of whirl is disorderly. The main frequency of stick-slip vibration in the low-frequency band is 0.1221 Hz and the period of stick-slip vibration is very close to 10 s through Fast Fourier (FFT) and Short-time Fourier transform (DTFT) methods. In the process of whirling, two frequencies, respectively, 0.05341 Hz and 155.5 Hz, play a major role. The frequency 0.05341 Hz is very close to the reciprocal of the period of 20 s when the peak energy spectrum density appears, indicating that the occurrence of whirl is very likely to be related to the natural frequency of the drilling tool. Through further time-frequency analysis, it also can be found that the occurrence of whirl and stick-slip is greatly related to the use of torsional impactors and jars.