Stability Analysis of Pipe With Connectors in Horizontal Wells

SPE Journal ◽  
2012 ◽  
Vol 17 (03) ◽  
pp. 931-941 ◽  
Author(s):  
Guohua Gao ◽  
Qinfeng Di ◽  
Stefan Miska ◽  
Wenchang Wang
Keyword(s):  
Unit Length ◽  
Contact Point ◽  
Point Contact ◽  
Vertical Plane ◽  
Elastic Beam ◽  
Beam Theory ◽  
Horizontal Wells ◽  
Critical Force ◽  
Practical Applications ◽  
Sucker Rod

Summary Except for coiled tubing, most tubular goods used for downhole operations (such as drillpipe and sucker rod) have connectors. Because a connector and the pipe body have different outer radii, the deformation and buckling behavior of a pipe with connectors constrained in a wellbore is much more complicated. However, most buckling models were established by neglecting the existence and effects of connectors. In this paper, buckling equations of a pipe with connectors in horizontal wells were derived with application of elastic-beam theory. The axis of an unbuckled pipe is a 2D curve in the vertical plane and has three configurations—no contact, point contact, and wrap contact. We derived the two critical distances between connectors, Lc1 and Lc2, beyond which a pipe changes its configuration from one to another. The authors proposed an algorithm to determine the critical force (Fcrs) of buckling by numerically solving the buckling equations using the fourth-order Ronge-Kuta method. Both the distance between two adjacent connectors (Lc) and the radius difference between a connector and the pipe body (∆rc) have significant impact on the critical force, in addition to net clearance between a pipe and wellbore (r0), bending stiffness (EI), and weight per unit length (w) of pipe. When Lc is small, radial deflection is negligible. Fcrs increases as ∆rc increases. However, when Lc is close to Lc1, effects of radial displacement become significant, and Fcrs decreases dramatically as ∆rc increases. Fcrs decreases as Lc increases when Lc Lc1, and it reaches its minimum at Lc=Lc1. When Lc > Lc1, Fcrs fluctuates as Lc increases. Some curves of Lc1, Lc2, and Fcrs, all in dimensionless forms, were calculated and presented in this paper for practical applications. Our numerical results show that the critical force may reduce by 20 to 60% for commonly used drillpipes and sucker rods with centralizers, which indicates that a pipe string designed without considering the effects of connectors may be risky. The results presented in this paper may provide some practical guidance for optimal design of centralizers for sucker-rod strings, or may avoid some risks because of improper design of drillpipe strings.

scholarly journals Displacement amplification ratio modeling of bridge-type nano-positioners with input displacement loss

2019 ◽  
Vol 10 (1) ◽  
pp. 299-307
Author(s):  
Jinyin Li ◽  
Peng Yan ◽  
Jianming Li
Keyword(s):  
Experimental Testing ◽  
Elastic Beam ◽  
Beam Theory ◽  
Element Analysis ◽  
Compliance Matrix ◽  
Amplification Ratio ◽  
Practical Applications ◽  
Analysis And Design ◽  
Proposed Model ◽  
Bridge Type

Abstract. This paper presents an improved modeling method for bridge-type mechanism by taking the input displacement loss into consideration, and establishes an amplification ratio model of bridge-type mechanism according to compliance matrix method and elastic beam theory. Moreover, the amplification ratio of the designed bridge-type nano-positioner is obtained by taking the guiding mechanism as the external load of bridge-type mechanism. Comparing with existing methods, the proposed model is more accurate, which is further verified by finite element analysis(FEA) and experimental test. The consistency of the results obtained from theoretical model, FEA and experimental testing indicates that the proposed model can accurately predict the amplification characteristics of nano-positioners, which helps the analysis and design of bridge-type nano-positioners in practical applications.

Smooth Asymmetric Two-Dimensional Indentation of a Finite Elastic Beam

2000 ◽  
Vol 68 (2) ◽  
pp. 357-360 ◽  
Author(s):  
M. Zhou ◽  
W. P. Schonberg
Keyword(s):  
Point Contact ◽  
Elastic Beam ◽  
Beam Theory ◽  
Contact Length ◽  
Solution Technique ◽  
Standard Methods ◽  
Local Stresses ◽  
Indentation Analysis ◽  
Load Displacement ◽  
Theory Solution

Standard methods of beam indentation analysis use a beam theory solution to obtain the load-displacement relationship and a Hertz solution to calculate local stresses. However, when the contact length exceeds the thickness of the beam point contact can no longer be assumed and Hertzian relations are no longer valid. This paper presents an improved superposition solution technique that uses a true elasticity solution to obtain the load-displacement relationship in non-Hertzian indentation problems.

Special-purpose downhole sucker rod pumps for directional and horizontal wells: results of pilot experiments in Tatneft

2019 ◽  
pp. 47-51
Author(s):  
K.V. Valovsky ◽  
◽  
G.Yu. Basos ◽  
V.M. Valovsky ◽  
A.V. Artyukhov ◽  
...  
Keyword(s):  
Horizontal Wells ◽  
Sucker Rod

scholarly journals Nonlinear ferro-electro-elastic beam theory

2009 ◽  
Vol 46 (11-12) ◽  
pp. 2397-2406 ◽  
Author(s):  
Uri Kushnir ◽  
Oded Rabinovitch
Keyword(s):  
Elastic Beam ◽  
Beam Theory

Wheel-Rail Multi-Point Contact Method for Railway Turnouts

2011 ◽  
Vol 97-98 ◽  
pp. 378-381
Author(s):  
Zhi Wei Chen ◽  
Linan Li ◽  
Shi Gang Sun ◽  
Jun Long Zhou
Keyword(s):  
Calculation Method ◽  
Normal Force ◽  
Contact Point ◽  
Point Contact ◽  
Contact Model ◽  
Contact Method ◽  
Elastic Contact ◽  
Simulation Calculation ◽  
Acute Change

A calculation method of wheel-rail multi-point contact based on the elastic contact model is introduced. Moreover, the simulation calculation of vehicles passing through branch lines of No.18 turnouts is carried out. The result showed that the acute change of wheel-rail normal force caused by the transfers of wheel-rail contact point between two rails can be avoid by wheel-rail multi-point contact method, and the transfers of wheel-rail normal force between two rails is smoother. The validity of wheel-rail multi-point contact method is verified.

Multi-Agent Form Closure Capture of a Generic 2D Polygonal Object Based on Projective Path Planning

2006 ◽  
Author(s):  
Pankaj Sharma ◽  
Anupam Saxena ◽  
Ashish Dutta
Keyword(s):  
Path Planning ◽  
Contact Point ◽  
Point Contact ◽  
Object Boundary ◽  
Actual Object ◽  
Contact Points ◽  
Correct Orientation ◽  
Novel Approach ◽  
Form Closure ◽  
Multi Agent

The study of multi-agent capture and manipulation of an object has been an area of active interest for many researchers. This paper presents a novel approach using Genetic Algorithm to determine the optimal contact points and the total number of agents (mobile robots) required to capture a stationary generic 2D polygonal object. After the goal points are determined the agents then reach their respective goals using a decentralized projective path planning algorithm. Form closure of the object is obtained using the concept of accessibility angle. The object boundary is first expanded and the robots reach the expanded object goal points and then converge on the actual object. This ensures that the agents reach the actual goal points at the same time and have the correct orientation. Frictionless point contact between the object and robots is assumed. The shape of the robot is considered a circle such that it can only apply force in outward radial direction from its center and along the normal to the object boundary at the contact point. Simulations results are presented that prove the effectiveness of the proposed method.

STUDYING THE CONTACT POINT AND INTERFACE MOVING IN A SINUSOIDAL TUBE WITH LATTICE BOLTZMANN METHOD

2001 ◽  
Vol 15 (09) ◽  
pp. 1287-1303 ◽  
Author(s):  
HAI-PING FANG ◽  
LE-WEN FAN ◽  
ZUO-WEI WANG ◽  
ZHI-FANG LIN ◽  
YUE-HONG QIAN
Keyword(s):  
Boundary Conditions ◽  
Contact Line ◽  
Lattice Boltzmann ◽  
Complex Geometry ◽  
Contact Point ◽  
Point Contact ◽  
Immiscible Fluids ◽  
Lattice Boltzmann Model ◽  
Stick Slip ◽  
Bounce Back

The multicomponent nonideal gas lattice Boltzmann model by Shan and Chen (S-C) is used to study the immiscible displacement in a sinusoidal tube. The movement of interface and the contact point (contact line in three-dimension) is studied. Due to the roughness of the boundary, the contact point shows "stick-slip" mechanics. The "stick-slip" effect decreases as the speed of the interface increases. For fluids that are non-wetting, the interface is almost perpendicular to the boundaries at most time, although its shapes at different position of the tube are rather different. When the tube becomes narrow, the interface turns a complex curves rather than remains simple menisci. The velocity is found to vary considerably between the neighbor nodes close to the contact point, consistent with the experimental observation that the velocity is multi-values on the contact line. Finally, the effect of three boundary conditions is discussed. The average speed is found different for different boundary conditions. The simple bounce-back rule makes the contact point move fastest. Both the simple bounce-back and the no-slip bounce-back rules are more sensitive to the roughness of the boundary in comparison with the half-way bounce-back rule. The simulation results suggest that the S-C model may be a promising tool in simulating the displacement behaviour of two immiscible fluids in complex geometry.

scholarly journals The Study of the Interaction of Different Arrangements of the Bottom-Hole Assembly with the Bottomhole and the Borehole Wall

2019 ◽  
pp. 58-68
Author(s):  
Ya. M. Kochkodan ◽  
A.I. Vasko
Keyword(s):  
Differential Equations ◽  
Contact Point ◽  
Point Contact ◽  
Drill String ◽  
Borehole Wall ◽  
Deviation Angle ◽  
Technological Parameters ◽  
Bottom Hole ◽  
Anisotropy Index ◽  
Bottom Hole Assembly

The article presents the main factors affecting the buckling when drilling vertical wells. The authors study analytically the effect of the weight on the bit and the force of the interaction of a drill string with a borehole wall using a uniform-sized arrangement of the bottom-hole assembly and the borehole wall which is located in a deviated wellbore when drilling in isotropic rocks in case the drilling direction coincides with the direction of the force acting on the bit. Differential equations of the elastic axis of the drill string are worked out. The solutions of these equations have given nondimensional dependences between the technological parameters. The authors have obtained the graphical dependences of the distance from the bit to the “drill string - borehole wall” contact point and the normal reaction of the bottom to the bit and the “drill string - borehole wall” clearance. The dependence for identifying the drilling anisotropy index in oblique beds is obtained. An interrelation between the anisotropy drilling index, the zenith angle, the bedding angle, the bottom-hole assembly, the borehole dimensions and the axial weight on the bit has been established. The authors have studied analytically the effect of the weight on the bit and the force of the “drill string - borehole wall” interaction, when installing the centralizer to the bottom-hole assembly. The differential equations of the elastic axis of the drill string with the centralizer in the bottom-hole assembly are obtained. It is established that with the increase in the axial weight on the bit and the “drill collars - borehole wall” clearance, the distance from the bit to the contact point of the borehole wall decreases; whereas with the increase of the deviation angle and the clearance, the pressure force of the column on the walls increases. It has also been established that the anisotropy drilling index reduces the distance from the bit to the point contact both in a slick BHA and in the bottom hole assembly with the centralizer. The presence of a centralizer in the bottom hole assembly increases the distance from the bit to the contact point between the string and the borehole wall, makes it possible to increase the weight on the bit without the risk of increasing a deviation angle.

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