Stability of the equilibrium of rotating drillstrings

Gulyaev, V. I.; Lugovoi, P. Z.; Belova, M. A.; Solov’ev, I. L.

doi:10.1007/s10778-006-0137-5

Cited by 13 publications

(17 citation statements)

References 4 publications

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“…Como [10] dealt with the case of lateral buckling of a cantilever bar subjected to a transverse following force and studied the stability of bending-torsional equilibrium. Another related topics is vibrations of drillstrings where the stability issues have been investigated, for example, by Gulyaev et al [11] and Liu et al [12]. Liu et al [12] presented a discrete system model to study the axial torsional dynamics of a drill string.…”

Section: Resultsmentioning

confidence: 99%

Structural stability of a light rotating beam under combined loads

2017

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms Abstract This paper investigates the structural stability of long boring or milling tools. The tool is modelled by a rotating cantilever beam that is subject to compression and torsion, manifested by semi-tangential torque. The three dimensional mathematical model is based on Euler-Bernoulli beam theory considering a linear three-dimensional problem. We obtain a dimensionless relationship between the relative importance of rotation, compression, and torsion that reveals the stability boundaries of the system.Consider a long boring or a milling tool (see Fig. 1(a)) modelled by a straight vertical cantilever beam. The beam rotates about its vertical axis as well as being subjected to torsion M t and compression mg. Due to the presence of torsion, we are not able to analyse the system in two-dimensions [1]. The compression can be modelled by a lumped mass m attached to the free end of the beam (see Fig. 2(a)) that is much larger than the mass of the beam. Thus, the mass of the beam might be neglected. The beam is considered to be prismatic, homogeneous, linearly elastic and inextensible. It is either in compression or in tension depending on whether it stands upward or downward, respectively. The described system might become unstable depending upon the speed of rotation, the compression, the torsion, or a combination of all three [1].The arrangement of the model and the corresponding notation can be seen in Fig. 2(a) where the gravitational acceleration is denoted by g, the angular velocity is ω, the centrifugal force is mω 2 d 1 , the compression is mg and the torsional moment vector is M t . Note that the twisting moment is assumed to be semi-tangential [3,4] depicted in Fig. 1(b), that is, the forces F acting on the beam generate an axial torque M t that is able to tilt about both the y and z axes. By taking into account only small displacement r = col v w and angles ψ , θ during buckling, the linearised form of the torque is M t = M t col 1 δ v /2 δ w /2 where M t = 4F a, and the bending components of M t come from its resolution with respect to the principal system (ξ, η, ζ) and by using the definition of the semitangential torque in the sense of Ziegler [3] (see Fig. 1(b) and (c)). In case of the principal system,

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Section: Resultsmentioning

confidence: 99%

Structural stability of a light rotating beam under combined loads

2017

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“…Including frictional damping generated by the surrounding cutting fluid and the rotational inertia, the governing equation of the system for lateral vibration is obtained taking into account of the fluid-structure interaction, the effect of the motion constraints, the gyroscopic effect caused by rotation, torque and compressive axial force. From the viewpoint of rotor dynamics and fluid-structure interaction, the equations of motion [18,[21][22][23][24] are given by (1) and (2) can be written in a uniform way as follows:…”

Section: The Equation Of Motionmentioning

confidence: 99%

“…At present, a lot of research work has been done on torsional and lateral vibration in BHA drill strings dynamics. Gulyaev [18] analyzed the quasistatic stability of a rotating drill string under longitudinal force and torque. In addition, he determined the critical rotary speed of drill strings and used the buckling mode shapes to locate the position of installing centralizers, which would avoid the contact of drill string and borehole, and raise the critical rotary speed.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Analysis of BTA Deep-Hole Drilling Shaft System

Ma¹,

Shen²

2018

dtetr

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Abstract. Numerical investigation was conducted into dynamics of deep-hole drilling shaft system. The rotating drilling shaft was modeled as a Rayleigh beam conveying the fluid and subjected to torque, compressive axial force and support constraints. From the viewpoint of rotor dynamics and fluid-structure interaction, the governing equation of the drilling shaft system for lateral vibration was obtained taking into account of the fluid-structure interaction, the rotational inertia, the gyroscopic effect, the effect of the motion constraints and frictional damping generated by the surrounding fluid. The influence of the cutting fluid flow velocity, rotational angular velocity, torque, compressive axial force, and the support constraints on natural frequency and stability of the drilling shaft system was examined. It has been found that the cutting fluid flow velocity, compressive axial force and torque decreases natural frequencies of the drilling shaft system, whereas rotational angular velocity and support constraints can improve the stability of the drilling shaft system.

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“…Chen and Geradin (1995) developed a transfer matrix to study the dynamics of BHA at various rotational speeds, WOBs and drilling fluids. Gulyaev et al (2006) derived constitutive equations to analyze buckling mode of drillstring under compressive forces.…”

Section: Lateral Vibrationmentioning

confidence: 99%

Experimental Investigation of the Effects of Rotational Speed and Weight on Bit on Drillstring Vibrations, Torque and Rate of Penetration

Bavadiya

Alsaihati

Ahmed

et al. 2017

Day 3 Wed, November 15, 2017

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Drillstring vibrations namely axial, lateral and torsional vibrations are the primary reason for downhole tool failure and reduction in rate of penetration (ROP). Factors like bit design, bottom hole assembly, bit-rock interaction, rotational speed, wellbore hydraulics, weight on bit (WOB) and drillstring-borehole interaction affect vibrations, out of which only rotational speed and WOB can be changed in real-time to minimize vibrations. It has been a topic of interest to understand and model downhole vibrations, minimize them and find an optimum range of drilling parameters to increase the drilling efficiency. This article presents the results of experimental studies conducted on a fully automated drilling rig to examine the effects of drilling parameters on drillstring vibrations, torque and rate of penetration. The study is different in terms of the high-speed range and the use of axial vibration transmitter to measure the vibration severity as per ISO standards. Experiments were performed on two different rock samples with varying strength. Perfect hole cleaning with negligible fluid flow effect was assumed. Each experiment was run for an average of six minutes collecting an average of 120 data points which were then averaged out for analysis. Parametric study was carried out to analyze the impacts of bit strength to rock strength ratio, bit constant and intrinsic specific energy on torque using existing model. As the drillstring was stiff and small, torsional oscillations were not observed and only lateral and axial vibrations were studied. Effect of drilling parameters and vibration on ROP was studied only on soft rock sample as ROP on hard rock was too small to be recorded Once the input parameters for the analytic model were methodically selected they show good agreement with the experimental data. The results of the parametric study revealed that estimation of torque relies heavily on the bit constant. Axial vibrations increased when rotational speed was near to the natural frequency of the drillstring which resulted in increase of ROP. Type of formation affected the magnitude of lateral and axial vibrations. Reducing both rotational speed and WOB helps to minimize lateral vibrations in hard formations while reducing rotational speed can effectively reduce axial vibrations.

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Stability of the equilibrium of rotating drillstrings

Cited by 13 publications

References 4 publications

Structural stability of a light rotating beam under combined loads

Structural stability of a light rotating beam under combined loads

Dynamic Analysis of BTA Deep-Hole Drilling Shaft System

Experimental Investigation of the Effects of Rotational Speed and Weight on Bit on Drillstring Vibrations, Torque and Rate of Penetration

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