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.

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.

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

Annular Squeeze Films With Inertial Effects

1983 ◽  
Vol 105 (3) ◽  
pp. 361-363 ◽  
Author(s):  
S. R. Turns
Keyword(s):  
Annular Plate ◽  
Equation Of Motion ◽  
Plate Motion ◽  
Squeezing Flow ◽  
Approximation Technique ◽  
Inertial Effects ◽  
Fluid Inertia ◽  
Governing Equations ◽  
Inertia Effects ◽  
Incompressible Newtonian Fluid

An analysis of the laminar squeezing flow of an incompressible Newtonian fluid between parallel plane annuli is presented in which a successive approximation technique is used to account for fluid inertia effects. An expression for the force generated by the fluid is developed and coupled to the equation of motion for the annular plate. Results are presented from the numerical integration of the governing equations for the plate motion.

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.

The Free Vibrations of Stiffened Drill Strings With Static Curvature

1967 ◽  
Vol 89 (1) ◽  
pp. 23-29 ◽  
Author(s):  
D. A. Frohrib ◽  
R. Plunkett
Keyword(s):  
Natural Frequencies ◽  
Free Vibrations ◽  
Drill String ◽  
Bending Stiffness ◽  
Mode Shapes ◽  
Static Tension ◽  
Lateral Vibration ◽  
Governing Equations ◽  
Deflection Curve ◽  
Wide Range

The natural frequencies of lateral vibration of a long drill string in static tension under its own weight are primarily the same as those of the equivalent catenary. These frequencies and the mode shapes are affected to a certain extent by the bending stiffness and to a greater extent by the static deflection curve due to lateral deflection of the bottom end. In this paper, the governing equations are derived and general solutions are given in an asymptotic expansion with the bending stiffness as the parameter. Specific numerical results are given in dimensionless form for the first three natural frequencies for a very wide range of horizontal tension and several appropriate values of bending stiffness for zero vertical static force at the bottom.

Free Vibration of Axially Loaded Laminated Conical Shells

1999 ◽  
Vol 66 (3) ◽  
pp. 758-763 ◽  
Author(s):  
L. Tong
Keyword(s):  
Free Vibration ◽  
Axial Load ◽  
Governing Equations ◽  
Load Effect ◽  
Critical Buckling Load ◽  
Conical Shells ◽  
Axial Tension ◽  
Axially Loaded ◽  
Constant Axial Load ◽  
Laminated Conical Shells

Analytical solutions for the three displacements are obtained, in the form of power series, directly from the three governing equations for free vibration of laminated conical shells under axial load. Numerical results are presented for free vibration of axially loaded laminated conical shells with different geometric parameters and under two types of boundary conditions. It is found that an axial tension increases the frequencies while an axial compression decreases the frequencies. For the shells studied, the effect of axial load on the lowest frequency of the shell is found to be not sensitive to change in semivertex angle when the applied axial load is kept as a constant fraction of the critical buckling load. However, the axial load effect becomes very sensitive to variation in semivertex angle when a constant axial load is applied.

Dynamic Response of Ground Surface Due to External Disturbance: Analytical Solution

2008 ◽  
Author(s):  
Hamid R. Hamidzadeh
Keyword(s):  
Mathematical Model ◽  
Analytical Solution ◽  
Wave Equations ◽  
External Disturbance ◽  
Ground Surface ◽  
Equation Of Motion ◽  
Elastic Half Space ◽  
Fourier Domain ◽  
Dynamics Analysis ◽  
Governing Equations

In this investigation the propagation of a harmonic disturbance on the surface of ground is considered. The medium is assumed to be a homogeneous and isotropic, continuous and infinite which can be modeled as an elastic half space medium. Implementing elasto-dynamics analysis, the governing equation of motion for the system is developed. The developed mathematical model formulates the displacement and stresses in the medium in terms of elastic dilatation and rotations and reduces the governing equations into three wave equations in terms of elastic dilatation and rotations. These equations are solved and boundary stresses are satisfied in Fourier domain and the displacement on the surface are provided in this domain.

On the Collapse of Offshore Pipelines under External Pressure and Axial Force

2013 ◽  
Vol 419 ◽  
pp. 134-139
Author(s):  
Neng Gan ◽  
Jiang Hong Xue
Keyword(s):  
Hydrostatic Pressure ◽  
Axial Force ◽  
Analytical Approach ◽  
Shell Theory ◽  
Ritz Method ◽  
Morphological Characteristics ◽  
External Pressure ◽  
Governing Equations ◽  
Offshore Pipelines ◽  
Axial Tension

The elastic collapse of long cylinders under combined external pressure and axial force was investigated using analytical approach. Long cylindrical pipelines laid on the seabed are subjected to external pressure, initial defect will cause the local collapse of the pipelines. Due to the change of subsea environments and construction conditions, circular pipelines are subjected not only to the hydrostatic pressure, but also to forces of other forms, such as axial tension or compression, so on and so forth. This paper studies the local collapse and the morphological characteristics of a circular pipelines subjected to hydrostatic pressure and axial force. Governing equations based on Karman-Donnell`s shell theory are derived and are solved using Ritz method.

Dynamic Analysis of Multi-Span Laminated Composite Coated Beams Carrying Multiple Accelerating Oscillators

2006 ◽  
Author(s):  
S. A. Eftekhari ◽  
M. Farid
Keyword(s):  
Finite Element ◽  
Arrival Time ◽  
Differential Quadrature Method ◽  
Equations Of Motion ◽  
Laminated Composite ◽  
Equation Of Motion ◽  
Algebraic Equations ◽  
The Finite Element Method ◽  
Governing Equations ◽  
Time Intervals

In this paper, the dynamics of a multi-span laminated composite coated beam subjected to a set of accelerating oscillators, by using a coupled finite element-differential quadrature method (DQM), is analyzed. First, using the finite element method, the governing equation of motion of the beam is reduced into a set of ordinary differential equations in time domain. Then DQM is employed to convert these equations together with the governing equations of motion of all moving oscillators into a set of algebraic equations. The efficiency and accuracy of the proposed technique are demonstrated by numerical examples. Furthermore, influence of various parameters such as lamina thickness, orientation of the coats, the number of spans, arrival time intervals, velocities and accelerations of the oscillators on the dynamic behavior of the system are investigated. The technique presented in this investigation is general and can be easily applied to any time-dependent problem.

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