Method of Dynamic Analysis for Rod-in-Hole Buckling

Tikhonov, V. S.; Safronov, Alexander I.; Gelfgat, Mikhail

doi:10.1115/esda2006-95059

Cited by 11 publications

(9 citation statements)

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“…In conducting laboratory experiments and numerical analysis in a perfect horizontal well without rotation, Menand et al 9 and Thikonov et al 10 found similar results about the relationship between λ number and the deformed shape of the drill pipes : λ close to 2.83 enables to predict the onset of the first helix, and λ close to 5.65 enables to predict the full helical drillstring deformation in a perfect wellbore geometry (without rotation). While many equations had been derived for perfect vertical, inclined, horizontal or curved wellbores, no theory were developed for actual well geometry, that is in a naturally tortuous wellbore.…”

Section: Effect Of Wellbore Geometrymentioning

confidence: 55%

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How Drillstring Rotation Affects Critical Buckling Load?

et al. 2008

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Buckling of tubulars inside wellbores has been the subject of many researches and articles in the past. However, these conservative theories have always followed the same assumptions : the wellbore has a perfect and unrealistic geometry (vertical, horizontal, deviated, curved), the friction and rotation effects are ignored, conditions relatively far from actual field conditions. How do tubulars buckle in actual field conditions, that is, in a naturally tortuous wellbore with friction and rotation ? Can we apply theories developed for perfect well conditions (no tortuosity, no friction, no rotation) to actual well conditions ?For the first time, this paper presents how the drillstring rotation affects the critical buckling load in actual field conditions. These new results have been obtained from an advanced model dedicated to drillstring mechanics successfully validated with laboratory tests.Firstly, this paper presents the new developments integrated in a recently advanced model for drillstring mechanics that enables to take into account the buckling phenomenon in any actual well trajectory. Indeed, some simultaneous torque-drag-buckling calculations are presented and allow to properly take into account the additional contact force generated in a post-buckling configuration, and as a consequence the additional torque at surface. Secondly, this paper shows the influence of friction and rotation on buckling loads for some practical and critical cases met in the drilling industry. These friction and rotation effects are demonstrated with an experimental set up that enables to confirm theoretical features. Lastly, this paper shows that using standard buckling criteria may lead to too conservative solutions, and that under specific circumstances, the drilling and completion engineer could safely operate in a buckling mode for a given time.These new results presented in this paper should improve significantly well planning and operational procedures to drill and operate more and more complex wells.

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Section: Effect Of Wellbore Geometrymentioning

confidence: 55%

“…Some authors 10,11,12 investigated the effect of tool-joints or connectors on the buckling behavior in horizontal wellbores. They concluded that the presence of tool joints may increase the critical helical buckling load up to 20 % but does not affect the critical sinusoidal load.…”

Section: Effect Of Tool-jointsmentioning

confidence: 99%

How Drillstring Rotation Affects Critical Buckling Load?

et al. 2008

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“…The model and method of solution is presented in full details in this paper (see also previous publications - Tikhonov et al 2006, Tikhonov and Safronov 2008, and Tikhonov and Safronov 2011 that permit other experts to validate and replicate the results presented here. Consequently, we believe the new dynamic stiff string model presents innovative capabilities for the industry to model drillstrings with both stiffness and radial clearance.…”

Section: Why Did We Develop the New Dynamic Stiff String Model?mentioning

confidence: 82%

“…The mathematical model for the dynamic stiff string T&D is based on the method of the drillstring dynamic analysis in a well (Tikhonov et al 2006). Originally, this method was designed for buckling (Tikhonov et al 2006) and whirling (Tikhonov and Safronov 2008) studies.…”

Section: Theoretical Basis Of the Modelmentioning

confidence: 99%

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Dynamic Model for Stiff String Torque and Drag

Tikhonov

Valiullin

Nurgaliev

et al. 2013

SPE/IADC Drilling Conference

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A dynamic stiff string torque and drag (T&D) model is presented that assumes steady state motion of the drillstring as its basis for calculations. Results are compared to previously published T&D models that are based on static equilibrium. The novelty of the new dynamic model is the ability to solve T&D operations of the entire drillstring from bit to top drive in reasonable time using standard engineering computers.The new approach is based on a 3D dynamic model of drillstring and BHA in an elastic borehole. It considers bending stiffness, torsional stiffness, contact forces, and friction with localization of contact points. A numerical method is described that has proven to have excellent convergence. Complete governing equations are provided and the method is described in detail to permit readers to replicate results.The dynamic model is compared to two static stiff string models. Comparisons are also provided for three conventional soft string models including the Lubinski-Paslay-Cernocky bending stress magnification factor. Three field case studies are presented for horizontal wells. One well is short radius with dogleg severity over 50 deg/100 ft and two wells are unconventional shale wells with doglegs up to 15 deg/100 ft. Predictions for surface torque and drag up and down for the new dynamic stiff string model are compared to the static stiff and soft string models. In many situations modeled the top-level results for surface torque and drag up/down are close enough for all six models to be within the uncertainty range associated with the commonly used, lumped-parameter friction factor. However, some major differences in hook load for sliding and slack off operations are observed, which are shown to be caused by differences in location and magnitude of contact force between the drillstring and wellbore. Further, significantly lower surface torque is predicted by the new dynamic stiff string compared to other models for one case history because of lower contact forces in the vertical section of the well. In fact, the key finding of this paper is that major differences are observed for contact forces for the new dynamic stiff string model compared to all five other models, including the two static stiff string models. These differences in contact forces are most significant when the drillstring has helically buckled or when doglegs in the wellbore are high. Contact forces have a large impact on local stress behavior, which is important for predictions of casing and drillpipe wear, drillstring fatigue, and failure points in the drillstring.Although several previous papers have published stiff string models there is no industry standard formulation. The main problem holding back the development of an industry standard stiff model is perhaps the complexity of the numerical algorithm and substantial running time. To address this problem, some previous stiff string models account for bending stiffness of the drillstring but not for radial clearance while others appear to model only portions of the drillstring ...

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A highly efficient beam-in-beam large sliding contact method for flexible multibody dynamics

Yang

Cheng³

et al. 2021

Comput Mech

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Method of Dynamic Analysis for Rod-in-Hole Buckling

Cited by 11 publications

References 0 publications

How Drillstring Rotation Affects Critical Buckling Load?

How Drillstring Rotation Affects Critical Buckling Load?

Dynamic Model for Stiff String Torque and Drag

A highly efficient beam-in-beam large sliding contact method for flexible multibody dynamics

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