Analysis of the Motion of Deep-Water Drill Strings—Part 2: Forced Rolling Motion

1965 ◽  
Vol 87 (2) ◽  
pp. 145-149
Author(s):  
M. A. Frost ◽  
J. C. Wilhoit
Keyword(s):  
Equation Of Motion ◽  
Drill String ◽  
Ocean Floor ◽  
Rolling Motion ◽  
Combined Effects ◽  
Flexible Cable ◽  
Drag Forces ◽  
Point Of Entry ◽  
Axial Tension ◽  
Short Beam

An equation of motion for a drill string, considering elastic, dynamic, and drag forces, was derived in a previous paper and was applied to two types of beam behavior: A beam having constant axial tension and a perfectly flexible cable. A drill string was then considered as consisting of short beam sections at the top and bottom, joined by a perfectly flexible cable. The lateral deflection of the drill string was obtained by joining the beam and cable solutions subject to boundary conditions at each junction. In this paper, the drill string is considered built-in at the ocean floor and to be experiencing a harmonic change of slope at the ocean surface imposed by roll (or pitch) of the ship, the ship remaining stationary vertically above the point of entry at the ocean floor. Examples are discussed and results are compared with experimentally measured values. The combined effects of roll and displacement are obtained by superposition of the two solutions.

Analysis of the Motion of Deep-Water Drill Strings—Part 1: Forced Lateral Motion

1965 ◽  
Vol 87 (2) ◽  
pp. 137-144 ◽  
Author(s):  
R. D. Graham ◽  
M. A. Frost ◽  
J. C. Wilhoit
Keyword(s):  
Equation Of Motion ◽  
Drill String ◽  
Subsequent Paper ◽  
Lateral Motion ◽  
Governing Equations ◽  
Flexible Cable ◽  
Drag Forces ◽  
Axial Tension ◽  
Short Beam ◽  
Variable Tension

An equation of motion for a drill string, considering elastic, dynamic, and drag forces, is derived. This equation is then applied to two types of drill-string behavior; i.e., a beam having constant axial tension and a perfectly flexible cable under variable tension. A drill string is then synthesized by subdivision into short beam sections at the top and bottom, joined by a flexible cable in the center. The lateral deflection of the drill string is obtained by joining the beam and cable solutions, subject to boundary conditions at each junction. The drill string is considered built-in at the ocean floor and is displaced harmonically at the surface by the ship. An example is discussed and results are compared with experimentally measured values. The effect of roll will be considered in a subsequent paper; as the governing equations have been linearized, these solutions may be superimposed.

The Effect of Axial Tension and Borehole Curvature on Torsion Limit of Drill String Threaded Connections

2021 ◽  
pp. 105555
Author(s):  
Feng Chen ◽  
Yonghao Huo ◽  
Haiyi Zhao ◽  
Qinfeng Di ◽  
Wenchang Wang ◽  
...  
Keyword(s):  
Drill String ◽  
Axial Tension ◽  
Threaded Connections

scholarly journals Helical post-buckling of a rod in a cylinder: with applications to drill-strings

2012 ◽  
Vol 468 (2142) ◽  
pp. 1591-1614 ◽  
Author(s):  
J. M. T. Thompson ◽  
M. Silveira ◽  
G. H. M. van der Heijden ◽  
M. Wiercigroch
Keyword(s):  
Petroleum Industry ◽  
Approximate Solutions ◽  
Drill String ◽  
Elastic Rod ◽  
Continuous Contact ◽  
Axial Tension ◽  
Cylindrical Casing ◽  
Post Buckling ◽  
Universal Graphs ◽  
Helical Buckling

The helical buckling and post-buckling of an elastic rod within a cylindrical casing arises in many disciplines, but is particularly important in the petroleum industry. Here, a drill-string, subjected to an end twisting moment combined with axial tension or compression, is particularly prone to buckling within its bore-hole—with potentially serious results. In this paper, we make a detailed theoretical study of this type of instability, deriving precise new results for the advanced post-buckling stage when the rod is in continuous contact with the cylinder. Results, including rigorous stability analyses and contact pressure assessments, are presented as equilibrium surfaces to facilitate comparisons with experimental results. Two approximate solutions give insight, universal graphs and parameters, for the practically relevant case of small angles, and highlight the existence of a critical cylinder diameter. Excellent agreement with experiments is achieved.

Effect of Drag Forces on Bit Weight in High-Curvature Well Bores

1992 ◽  
Vol 114 (3) ◽  
pp. 175-180 ◽  
Author(s):  
D. N. Rocheleau ◽  
D. W. Dareing
Keyword(s):  
Drill String ◽  
Horizontal Drilling ◽  
Drag Forces

This paper gives a method of analysis for determining drill string weight required to develop a given bit force while drilling through and out of high-curvature well bores. The analysis is directed at medium radius well bores having radii of curvature ranging between 286 ft (87 m) and 955 ft (291 m), which are typically found in horizontal drilling. Sample calculations show how friction within the angle building portion of the well affect bit force.

scholarly journals Effect of friction on transverse vibration of string under moving load

2021 ◽  
Author(s):  
Kamal Kishor Prajapati ◽  
Soumyajit Roy
Keyword(s):  
Mathematical Model ◽  
Coefficient Of Friction ◽  
Transverse Vibration ◽  
Moving Load ◽  
Equation Of Motion ◽  
Harmonic Load ◽  
Axial Tension ◽  
Moving Harmonic Load ◽  
Catenary System ◽  
Basic Characteristics

Abstract Many engineering applications involve exerting moving harmonic load on a string like structure. Usually the interface between these structures and the moving load has some friction. A common example is a pantograph catenary system, which is used in locomotives for power collection. The aim of this paper is to develop a mathematical model of a simplified system consisting of infinitely long axially tensioned continuum and a moving harmonic load with friction acting at the interface. Equation of motion has been derived by resolving forces at that point. Subsequently the basic characteristics of the system are obtained by solving the model numerically. It is observed that the effect of friction obtained is negligibly low higher value of axial tension, but can significantly increase the string response at a particular range of coefficient of friction value when the axial tension is low.

Effect of Parametric Excitation on Ship Rolling Motion in Random Waves

1982 ◽  
Vol 26 (04) ◽  
pp. 246-253
Author(s):  
J. B. Roberts
Keyword(s):  
Parametric Excitation ◽  
Stochastic Averaging ◽  
Equation Of Motion ◽  
Rolling Motion ◽  
Damping Factor ◽  
Random Waves ◽  
Response Distribution ◽  
Fokker Planck Equations ◽  
Quadratic Damping ◽  
Ship Rolling

An equation of motion for uncoupled ship rolling motion in irregular seas is considered in which parametric excitation, arising from the time dependence of the restoring moment, is included. It is shown that, when the damping is light, the method of stochastic averaging can be applied to yield an approximate Markov model for the rolling motion. Appropriate Fokker-Planck equations are given from which some simple expressions for the stationary response distribution are derived. For the case of linear damping it is found that the motion is unstable if the damping factor is sufficiently small. The inclusion of a quadratic damping term in the equation of motion is shown to limit the unstable motion predicted by the linear theory. Explicit expressions for the distribution of the roll response are derived for the case of combined linear and quadratic damping. The case of purely parametric excitation is considered in some detail.

Sectionalized Mechanical Models of Drilling Tool of Trenchless Directional Drilling

2012 ◽  
Vol 268-270 ◽  
pp. 1190-1193
Author(s):  
Hui Xia ◽  
Yi Hua Dou ◽  
Xin He Wang ◽  
Jiang Wen Xu
Keyword(s):  
Axial Compression ◽  
Working Conditions ◽  
Mechanical Analysis ◽  
Drill String ◽  
Drill Bit ◽  
Straight Section ◽  
Directional Drilling ◽  
Drilling Tool ◽  
Horizontal Section ◽  
Axial Tension

There are three working conditions namely drilling a guide hole, expanding the guide hole and pulling back pipeline in trenchless directional drilling. The position of drill string in the wellbore and loads exerted on the drill string varied in different working conditions. The models of buckling analysis of drill strings under compression, mechanical analysis of drill string under axial compression near drill bit in inclined straight section, mechanical analysis of drill string with multi-centralizers under axial compression near drill bit in inclined straight section, mechanical analysis of drill string near drill bit under axial compression in horizontal section, mechanical analysis of drill string near drill bit under axial tension in horizontal section, mechanical analysis of drill strings near drill bit under axial tension in inclined straight section and mechanical analysis of drill string in failed well are established based on the characteristic of loads and trajectories in each section. The establishment of sectionalized mechanical model of drilling tool is the fundament of further study of force analysis, deformation analysis and stress analysis.

The E-ring: interactions with plasma and implications for its evolution

1984 ◽  
Vol 75 ◽  
pp. 599-602
Author(s):  
T.V. Johnson ◽  
G.E. Morfill ◽  
E. Grun
Keyword(s):  
Time Scale ◽  
Particle Density ◽  
High Energy ◽  
Particle Removal ◽  
Density Region ◽  
Drag Forces ◽  
Orbit Evolution ◽  
History Of ◽  
Ring Particle ◽  
Ring Material

A number of lines of evidence suggest that the particles making up the E-ring are small, on the order of a few microns or less in size (Terrile and Tokunaga, 1980, BAAS; Pang et al., 1982 Saturn meeting; Tucson, AZ). This suggests that a variety of electromagnetic and plasma affects may be important in considering the history of such particles. We have shown (Morfill et al., 1982, J. Geophys. Res., in press) that plasma drags forces from the corotating plasma will rapidly evolve E-ring particle orbits to increasing distance from Saturn until a point is reached where radiation drag forces acting to decrease orbital radius balance this outward acceleration. This occurs at approximately Rhea's orbit, although the exact value is subject to many uncertainties. The time scale for plasma drag to move particles from Enceladus' orbit to the outer E-ring is ~104yr. A variety of effects also act to remove particles, primarily sputtering by both high energy charged particles (Cheng et al., 1982, J. Geophys. Res., in press) and corotating plasma (Morfill et al., 1982). The time scale for sputtering away one micron particles is also short, 102 - 10 yrs. Thus the detailed particle density profile in the E-ring is set by a competition between orbit evolution and particle removal. The high density region near Enceladus' orbit may result from the sputtering yeild of corotating ions being less than unity at this radius (e.g. Eviatar et al., 1982, Saturn meeting). In any case, an active source of E-ring material is required if the feature is not very ephemeral - Enceladus itself, with its geologically recent surface, appears still to be the best candidate for the ultimate source of E-ring material.

Saturn's E, G and F rings: modulated by the plasma sheet

1984 ◽  
Vol 75 ◽  
pp. 597
Author(s):  
E. Grün ◽  
G.E. Morfill ◽  
T.V. Johnson ◽  
G.H. Schwehm
Keyword(s):  
Solar Wind ◽  
Direct Contact ◽  
Transport Processes ◽  
Time Variable ◽  
Dust Particles ◽  
Spatial Diffusion ◽  
Drag Forces ◽  
Orbit Perturbation ◽  
Time Variations ◽  
F Ring

ABSTRACTSaturn's broad E ring, the narrow G ring and the structured and apparently time variable F ring(s), contain many micron and sub-micron sized particles, which make up the “visible” component. These rings (or ring systems) are in direct contact with magnetospheric plasma. Fluctuations in the plasma density and/or mean energy, due to magnetospheric and solar wind processes, may induce stochastic charge variations on the dust particles, which in turn lead to an orbit perturbation and spatial diffusion. It is suggested that the extent of the E ring and the braided, kinky structure of certain portions of the F rings as well as possible time variations are a result of plasma induced electromagnetic perturbations and drag forces. The G ring, in this scenario, requires some form of shepherding and should be akin to the F ring in structure. Sputtering of micron-sized dust particles in the E ring by magnetospheric ions yields lifetimes of 102to 104years. This effect as well as the plasma induced transport processes require an active source for the E ring, probably Enceladus.

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