Examination of Commercial Casing Collapse Strength Under Axial Loading

1982 ◽  
Vol 104 (4) ◽  
pp. 343-348 ◽  
Author(s):  
T. Tamano ◽  
Y. Inoue ◽  
H. Mimura ◽  
S. Yanagimoto
Keyword(s):  
Axial Load ◽  
Axial Stress ◽  
Axial Loading ◽  
External Pressure ◽  
Plastic Collapse ◽  
Slight Effect ◽  
Collapse Pressure ◽  
Minimum Value ◽  
Collapse Strength ◽  
Casing Collapse

Collapse testing of commercial API grade 7-in. casing was conducted under combined external pressure and axial load. The measured collapse pressure was considerably higher than the API minimum value, especially for the large D/t ratio, as expected. For the casings of large D/t ratio, the measured collapse pressure was a little smaller than the theoretical value for ideal pipe and the axial stress had a slight effect on the collapse pressure. In the range of plastic collapse, the measured collapse pressure was not less than the yield pressure for ideal pipe except near the boundary of the elastic and plastic collapse ranges.

Experimental Study on the Effect of Axial Tension Load on the Collapse Strength of Oilwell Casing

1982 ◽  
Vol 22 (05) ◽  
pp. 609-615 ◽  
Author(s):  
T. Kyogoku ◽  
K. Tokimasa ◽  
H. Nakanishi ◽  
T. Okazawa
Keyword(s):  
Experimental Data ◽  
Theoretical Analysis ◽  
Testing Machine ◽  
External Pressure ◽  
Tension Stress ◽  
Plastic Collapse ◽  
Collapse Pressure ◽  
Axial Tension ◽  
Collapse Strength ◽  
Tension Load

Abstract This paper discusses a newly developed collapse testing machine that permits investigation of practical performances of oilwell casings. Although a theoretical performances of oilwell casings. Although a theoretical analysis has shown that "axial tension stress has no effect on collapse pressure in the elastic case," this theory is not applied to the design of casing string because of lack of useful experimental data or authorized recommendation. To investigate the effect of axial tension load, full-size commercial casings have been tested under combined loading of axial tension load and external pressure. From the experimental results, the theory mentioned was proved in the case of so-called high-collapse casing, which has been used widely in recent years. Also shown is the applicable d/h range, which is wider than API's elastic collapse range. If the results of this experiment were applied to the design of a casing program, an economical and safe one could be obtained. program, an economical and safe one could be obtained. Introduction Recently, improved drilling techniques have permitted deeper and deeper oil and gas wells. As well depth increases, steel pipes for well casings receive greater external pressure and axial tension load because of the weight of the casing string. High-collapse casing, which has higher collapse strength per unit weight, has become easily available. To select and to design casing for such wells properly and economically, estimating collapse strength of the casing under axial tension load is very important. Much research and many experiments concerning collapse problems on casing, drillpipe, and tubing has been conducted by 1939. A theoretical analysis showed that axial tension stress lowers the collapse pressure in the case of plastic collapse and that axial tension stress has no effect on collapse pressure in the elastic case. Although collapse tests under axial tension load simulating oilwell casing in service were conducted on 2-in.-OD tubings, the theory for the effect of axial tension stress in the elastic collapse had not been proved sufficiently. There are few published experimental proved sufficiently. There are few published experimental data on collapse strength under axial tension load. In 1968, API summarized the collapse data and showed the formulas for collapse pressure and for collapse pressure under axial tension stress in the case of plastic collapse. The purpose of our study is to show how the collapse strength of commercial casings with large OD's behaves under the axial tension load, especially in the case of elastic collapse. To test the large-size casings, a multipurpose collapse testing machine that can simulate the service condition of oilwell casing has been developed. Statement of the Problem The collapse strength of casings under combined external pressure and axial tension load may be calculated from pressure and axial tension load may be calculated from Ref. 6's Formula 1.1.5.1: ....................(1) SPEJ p. 609

Collapse of Worn Casing

1977 ◽  
Vol 99 (1) ◽  
pp. 208-214 ◽  
Author(s):  
C. E. Murphey
Keyword(s):  
Yield Strength ◽  
Lower Bounds ◽  
Wall Thickness ◽  
Axial Load ◽  
External Pressure ◽  
Upper And Lower Bounds ◽  
Percentage Reduction ◽  
Steel Tubes ◽  
Collapse Pressure ◽  
Severe Wear

Collapse tests were performed on one-in. dia steel tubes with flats milled on the exterior to simulate worn casing. External pressure and axial load were applied to the tubs having a range of wall thickness, yield strength, and degree of wear. Empirical correlation of the data and comparison with elastic collapse calculations indicate the percentage reduction in collapse pressure due to wear. This reduction is predictable within upper and lower bounds. While the milled external flat may not accurately simulate severe internal wear, the correlation is adequate for less than severe wear to give an indication of remaining strength.

scholarly journals An Analytical Approach to the Analysis of Inhomogeneous Pipes under External Pressure

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Massimiliano Fraldi ◽  
Federico Guarracino
Keyword(s):  
Hydrostatic Pressure ◽  
Analytical Approach ◽  
Specific Problem ◽  
External Pressure ◽  
Compressive Yield Strength ◽  
Plastic Collapse ◽  
External Hydrostatic Pressure ◽  
Collapse Pressure ◽  
Local Yielding ◽  
Analytical Expressions

Pipes for deep-water applications possess a diameter-to-thickness ratio in a region where failure is dominated by both instability and plastic collapse. This implies that prior to failure the compressive yield strength of the material must be exceeded, followed by ovalisation and further local yielding. This paper presents an investigation into the mechanics of this specific problem and develops an analytical approach that accounts for the effects of geometrical and material data on the collapse pressure of inhomogeneous rings under external hydrostatic pressure. The analytical expressions have been correlated to numerical and experimental test data, proving their accuracy.

Plastic Collapse Behaviors of Tubulars With Recess Patterns

2015 ◽  
Author(s):  
Haifeng Zhao ◽  
David Iblings ◽  
Aleksey Barykin ◽  
Mohamed Mehdi
Keyword(s):  
Empirical Relationship ◽  
External Pressure ◽  
Reduction Factor ◽  
Strength Reduction ◽  
Plastic Collapse ◽  
Strength Reduction Factor ◽  
Periodic Distribution ◽  
Collapse Strength ◽  
Post Buckling ◽  
Collapse Behavior

The collapse strength of tubulars with recess patterns machined into their walls is an important topic for oilfield downhole tools as it applies to perforating guns, prepacked sand screens, and perforated and slotted liners. This paper presents a study of the plastic collapse behavior of thick-walled tubulars (those with an outside diameter to thickness ratio of approximately 10) having different patterns of circular recesses (blind holes partially machined into the tubing wall) that are subjected to external pressure. An empirical relationship between the reduction in collapse strength and the periodic distribution of recesses was constructed to account for the weakening effects of recess diameter, recess depth, axial spacing, angular phasing, etc. This strength reduction factor was introduced into the Tamano formula to predict collapse strength of recessed tubulars. Applicability of this empirical formula was validated with the aid of nonlinear, post-buckling Finite Element Analyses (FEA). The modeling approach was verified by full-scale physical tests. However, results of the physical testing are not presented in this paper. The strength reduction factor in combination with the Tamano formula provides a simple way of parametrically predicting the collapse strength of tubulars having circular recess patterns.

Plastic Collapse Behaviors of Tubulars with Recess Patterns—Application in Hollow Carrier Perforating Guns

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
Haifeng Zhao ◽  
David Iblings ◽  
Aleksey Barykin ◽  
Mohamed Mehdi
Keyword(s):  
Empirical Relationship ◽  
External Pressure ◽  
Reduction Factor ◽  
Strength Reduction ◽  
Oil Field ◽  
Plastic Collapse ◽  
Strength Reduction Factor ◽  
Periodic Distribution ◽  
Collapse Strength ◽  
Collapse Behavior

The collapse strength of tubulars with recess patterns machined into their walls is an important topic for oil field downhole tools, especially in hollow carrier perforating gun systems. This paper presents a study of the plastic collapse behavior of thick-walled tubulars (those with an outside diameter to thickness ratio of approximately ten) having different patterns of circular recesses (blind holes partially machined into the tubing wall) that are subjected to external pressure. An empirical relationship between the reduction in collapse strength and the periodic distribution of recesses was constructed to account for the weakening effects of recess diameter, recess depth, axial spacing, angular phasing, etc. This strength reduction factor was introduced into the Tamano formula to predict collapse strength of recessed tubulars. Applicability of this empirical formula was validated with the aid of nonlinear, postbuckling finite element analyses (FEA). The strength reduction factor in combination with the Tamano formula provides a simple way of parametrically predicting the collapse strength of tubulars having circular recess patterns.

FEM Analysis of the Collapse Strength of a Tube

1986 ◽  
Vol 108 (2) ◽  
pp. 158-164 ◽  
Author(s):  
K. Tokimasa ◽  
K. Tanaka
Keyword(s):  
Residual Stress ◽  
Fem Analysis ◽  
Plastic Collapse ◽  
Round Tube ◽  
Collapse Pressure ◽  
Hardening Behavior ◽  
Collapse Strength ◽  
Inner Surface ◽  
Plastic Hardening ◽  
New Formula

Using the FEM program, the effects of geometry, residual stress and the elasticplastic behavior of material on the collapse strength of a tube is analyzed and the following results are obtained. The plastic collapse pressure is maximum when the circumferential residual stress on the inner surface is tensile and is equal to 0.7σy. The plastic collapse pressure of a perfectly round tube can be approximately estimated by the following equation independent of the plastic-hardening behavior of the material: P = 2σ0.04 (D/t − 1)/(D/t)2. Based on these FEM results, a new formula is presented to evaluate the collapse strength of a tube.

Axisymmetric Elastic-Plastic Buckling of Axial and Pressure Loaded Cylinders

1984 ◽  
Vol 198 (4) ◽  
pp. 243-259 ◽  
Author(s):  
J G A Croll
Keyword(s):  
Numerical Solutions ◽  
Axial Stress ◽  
Axial Loading ◽  
Radial Pressure ◽  
Plastic Collapse ◽  
Pressure Loading ◽  
End Conditions ◽  
Surface Yield ◽  
Full Plasticity ◽  
Ring Stiffener

An analytical approach to the axisymmetric elastic buckling of isotropic cylinders, under arbitrary combinations of radial pressure and axial loading, is used as the basis of a first surface yield and a first full plasticity criterion of plastic collapse. Bending disturbances caused by the boundary constraint of both Poisson bulging under axial loading and the effects of arbitrary radial pressure loading are combined with any prescribed initial geometric errors to provide total ‘equivalent imperfection parameters’ on an otherwise perfectly cylindrical prebuckling state. Elasto-plastic collapse loads are then summarized in terms of just three parameters: the total equivalent membrane and bending imperfections parameters and the ratio of the minimum elastic classical critical axial stress to the material yield stress. The ease with which shells of arbitrary end conditions or internal ring stiffener supports can be treated, the consideration that the results so closely reproduce and extend the more elaborate numerical solutions, and the possible simplifications of the method, make it an ideal basis for design against axisymmetric collapse.

Elastic-Plastic Solutions for Open-End Thick Walled Cylinders Subjected to Internal and External Pressures

2008 ◽  
Author(s):  
R. D. Dixon ◽  
E. H. Perez
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Yield Criterion ◽  
External Pressure ◽  
Plastic Collapse ◽  
Elastic Instability ◽  
Element Analysis ◽  
Collapse Pressure ◽  
Elastic Plastic ◽  
External Pressures

Available theoretical solutions for the collapse pressure of open-end thick walled cylinders based on the Vo n Misses yield criterion are very limited. The known elastic-plastic theoretical solutions are primarily based on the Tresca yield criterion. So far, little study has been devoted to fairly thick open-end cylinders under external pressure. This can be performed by finite element analysis that considers material plasticity. In this paper the authors propose the use of simple formulae for the solution of the collapse internal and external pressures of open-end cylinders. The proposed formulae provide excellent agreement with finite element results obtained by the authors. Also criterion is provided for the interaction of elastic instability and plastic collapse of open-end cylinders subjected to external pressure.

Numerical-Analytical Prediction of the Collapse of Flexible Pipes Under Bending and External Pressure

2012 ◽  
Author(s):  
Walter C. Loureiro ◽  
Ilson P. Pasqualino
Keyword(s):  
Numerical Models ◽  
External Pressure ◽  
Analytical Prediction ◽  
Collapse Pressure ◽  
Analytical Formulation ◽  
Collapse Strength ◽  
Industry Standards ◽  
Flexible Pipes ◽  
Analytical Approaches ◽  
Good Agreement

This work gathers the phenomena indicated through the available literature and industry standards as determinant in the evaluation of the collapse of flexible pipes under combined bending and external pressure. It also proposes a complete analytical formulation to assess the collapse strength. The effects of dimensional variations and added ovalization due to bending are combined to evaluate the final collapse pressure. Numerical models are generated for comparison purposes and experimental results are used to validate the formulation proposed. The good agreement obtained between numerical and analytical predictions show that is possible to determine the curve collapse of flexible pipes through analytical approaches.

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