The Effect of Length: Diameter Ratio on Collapse of Casing

1984 ◽  
Vol 106 (2) ◽  
pp. 160-165 ◽  
Author(s):  
N. C. Huang ◽  
P. D. Pattillo
Keyword(s):  
Axial Load ◽  
External Pressure ◽  
Field Application ◽  
Diameter Ratio ◽  
Finite Cylinder ◽  
Oil Well ◽  
Steel Mill ◽  
Cross Sectional ◽  
Axial Tension ◽  
Collapse Resistance

This paper presents an analysis of the cross-sectional collapse of a cylinder of finite length loaded simultaneously by an axial tension (which may be zero) and external pressure. The calculation is based on Sanders’ nonlinear shell equations with plasticity introduced via the concept of effective stress from a uniaxial tension test. The finite cylinder is an appropriate model of oil well casing as it undergoes quality control testing in the steel mill where the edges of the cylinder are usually fixed in the case of nonzero axial load and free in the case of zero axial load. However, in field application, the length: diameter ratio of casing is such that the cylinder may be considered infinite. Guidelines contained herein permit prediction of the collapse resistance of field casing from the results of mill tests performed on short samples.

Collapse of Imperfect Tubulars

1986 ◽  
Vol 108 (3) ◽  
pp. 214-220
Author(s):  
P. D. Pattillo ◽  
N. C. Huang
Keyword(s):  
Axial Load ◽  
Nonlinear Response ◽  
External Pressure ◽  
Cross Sectional ◽  
Collapse Resistance ◽  
The Cross ◽  
Eventual Collapse

The nonlinear response and eventual collapse of a cylinder loaded by resultant external pressure and axial load is analyzed. The cross-sectional description of the cylinder is sufficiently general to include ovality, eccentricity, and local thickness anomalies. Applications of the model include the prediction of minimum collapse resistance of commercial tubulars.

Collapse of Oil Well Casing

1982 ◽  
Vol 104 (1) ◽  
pp. 36-41 ◽  
Author(s):  
N. C. Huang ◽  
P. D. Pattillo
Keyword(s):  
External Pressure ◽  
Critical Conditions ◽  
Oil Well ◽  
Infinite Length ◽  
Empirical Formulas ◽  
Plastic Buckling ◽  
Incremental Theory ◽  
Axial Tension ◽  
Strain Formulation ◽  
Theoretical Results

This paper is concerned with the theoretical study of the collapse of oil well casing under various loading conditions. The analysis is based on a model of a cylindrical shell of infinite length subjected to an axial tension and an external pressure. It is found that when the thickness-radius ratio of the casing is sufficiently small, collapse of the casing may take place in a form of plastic buckling. Critical conditions for plastic buckling are derived based on the J2-incremental theory and the J2-deformation theory. Another type of collapse is caused by the realization of the ultimate strength of the material. Critical conditions in the second case of collapse are calculated based on a plane strain formulation associated with the J2-incremental theory. The theoretical results obtained in this paper correspond well with empirical formulas developed earlier by the API for the design of oil well casing.

Collapse of Oil Well Casing With Ovality

1985 ◽  
Vol 107 (1) ◽  
pp. 128-134 ◽  
Author(s):  
P. D. Pattillo ◽  
N. C. Huang
Keyword(s):  
Nonlinear Response ◽  
External Pressure ◽  
Oil Well ◽  
Infinite Length ◽  
Service Environment ◽  
Collapse Resistance ◽  
Eventual Collapse ◽  
Design Calculations ◽  
Model Oil ◽  
Interesting Alternative

The nonlinear response and eventual collapse of an initially imperfect cross section of a cylinder of infinite length is analyzed. The cylinder is loaded by external pressure and axial load and is intended to model oil well casing in a service environment. Results from the analysis agree well with experimental data and provide an interesting alternative to current empirical/statistical methods for determining the minimum collapse resistance of casing for use in design calculations.

scholarly journals Predicting Pipeline Collapse Resistance

2000 ◽  
Author(s):  
Duane DeGeer ◽  
J. J. Roger Cheng
Keyword(s):  
Prediction Method ◽  
External Pressure ◽  
Test Results ◽  
Spreadsheet Program ◽  
Axial Tension ◽  
Collapse Resistance ◽  
Inelastic Material ◽  
Post Buckling ◽  
Manufacturing History ◽  
Semi Empirical

Much research has been performed over the past twenty-five years to refine our basic understanding of tubular stability, which includes bifurcation, imperfect systems, factors influencing tubular stability and post-buckling behaviour. Tubular instability resulting from load combinations is not a trivial topic, particularly when inelastic material behaviour occurs. Many influencing factors must be considered when attempting to understand (and predict) the onset of instability. Many existing collapse predictive methods are either simplistic or involve advanced plasticity or finite element methods. Simplistic methods are typically semi-empirical, and contain a degree of uncertainty resulting in conservative collapse predictions. Nonetheless, they are generally considered satisfactory for design purposes. Advanced methods normally involve high-end calculations using specialized software programs that might not be available for general use. Therefore, a relatively easy-to-use method that accurately predicts the actual collapse resistance is, in many cases, the most desirable option. This paper presents a collapse predictive methodology, developed from a variety of research projects performed over the last fifteen years. The prediction method, which can easily be entered into a spreadsheet program, is applicable to most forms of tubular members, including pipelines. Applicable load combinations include external pressure, axial tension and bending. An overview of the parameters influencing collapse resistance is also provided, including manufacturing history, material modelling, and tubular geometry and imperfections. Also presented is a summary of accuracy of the method to predict some test results. The test database largely contains results of collapse tests on tubular members subject to only external pressure, and axial tension with external pressure. The adaptation of the method to include external pressure with bending is summarized, and the accuracy of the prediction method is demonstrated by predicting the results of the Oman-India and Blue Stream pipeline collapse test programs, and comparing these predictions with those of other well known methodologies.

scholarly journals Experimental Study on the Behavior of X-Section Pile Subjected to Cyclic Axial Load in Sand

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Yiwei Lu ◽  
Hanlong Liu ◽  
Changjie Zheng ◽  
Xuanming Ding
Keyword(s):  
Axial Load ◽  
Large Scale ◽  
Cross Sectional Area ◽  
Load Test ◽  
Dynamic Responses ◽  
Scale Model ◽  
Loading Frequency ◽  
Sectional Area ◽  
Cross Sectional ◽  
Shaft Friction

X-section cast-in-place concrete pile is a new type of foundation reinforcement technique featured by the X-shaped cross-section. Compared with a traditional circular pile, an X-section pile with the same cross-sectional area has larger side resistance due to its larger cross-sectional perimeter. The behavior of static loaded X-section pile has been extensively reported, while little attention has been paid to the dynamic characteristics of X-section pile. This paper introduced a large-scale model test for an X-section pile and a circular pile with the same cross-sectional area subjected to cyclic axial load in sand. The experimental results demonstrated that cyclic axial load contributed to the degradation of shaft friction and pile head stiffness. The dynamic responses of X-section pile were determined by loading frequency and loading amplitude. Furthermore, comparative analysis between the X-section pile and the circular pile revealed that the X-section pile can improve the shaft friction and reduce the cumulative settlement under cyclic loading. Static load test was carried out prior to the vibration tests to investigate the ultimate bearing capacity of test piles. This study was expected to provide a reasonable reference for further studies on the dynamic responses of X-section piles in practical engineering.

Downhole CO2 partial pressure calculation and tubing material selection – a case study of an offshore oil field in the South China Sea

2016 ◽  
Vol 63 (5) ◽  
pp. 414-420 ◽  
Author(s):  
Wei Yan ◽  
Yong Xiang ◽  
Wenliang Li ◽  
Jingen Deng
Keyword(s):  
Partial Pressure ◽  
Pressure Profile ◽  
Field Application ◽  
Separation Process ◽  
Oil Field ◽  
Oil Well ◽  
Content Type ◽  
Calculating Method ◽  
Oil Gas

Purpose This paper aims to establish the downhole CO2 partial pressure profile calculating method and then to make an economical oil country tubular goods (OCTG) anti-corrosion design. CO2 partial pressure is the most important parameter to the oil and gas corrosion research for these wells which contain sweet gas of CO2. However, till now, there has not been a recognized method for calculating this important value. Especially in oil well, CO2 partial pressure calculation seems more complicated. Based on Dolton partial pressure law and oil gas separation process, CO2 partial pressure profile calculating method in oil well is proposed. A case study was presented according to the new method, and two kinds of corrosion environment were determined. An experimental research was conducted on N80, 3Cr-L80 and 13Cr-L80 material. Based on the test results, 3Cr-L80 was recommended for downhole tubing. Combined with the field application practice, 3Cr-L80 was proved as a safety and economy anti-corrosion tubing material in this oil field. A proper corrosion parameter (mainly refers to CO2 partial pressure and temperature) can ensure a safety and economy downhole tubing anti-corrosion design. Design/methodology/approach Based on Dolton partial pressure law and oil gas separation process, CO2 partial pressure profile calculating method in oil well is proposed. An experimental research was conducted on N80, 3Cr-L80 and 13Cr-L80 material. A field application practice was used. Findings It is necessary to calculate the CO2 partial pressure properly to ensure a safety and economy downhole tubing (or casing) anti-corrosion design. Originality/value The gas and oil separation theory and corrosion theory are combined together to give a useful method in downhole tubing anti-corrosion design method.

Stress concentrations due to axial tension and bending of loaded axisymmetric projections

1983 ◽  
Vol 18 (1) ◽  
pp. 7-14 ◽  
Author(s):  
T H Hyde ◽  
B J Marsden
Keyword(s):  
Stress Concentration ◽  
Diameter Ratio ◽  
The Finite Element Method ◽  
Stress Concentrations ◽  
Axial Tension ◽  
Bending Loads ◽  
Concentration Factors ◽  
Stress Concentration Factors ◽  
D Values ◽  
Existing Data

The finite element method has been used to investigate the behaviour of axisymmetric loaded projections (e.g., bolts) subjected to axial tension and bending. The results show that existing data for stepped shafts, which have the axial tension and bending loads applied remote from the region of the step, cannot be applied to loaded projections with the same geometry. For h/d (head thickness to shank diameter ratio) values greater than 0.66 and 0.41 for axial tension and bending, respectively, the stress concentration factors are independent of h/d, load position, and D/d (head diameter to shank diameter ratio) for D/d in the range 1.5 ≤ D/d ≤ 2.0. Smaller h/d values result in large increases in the stress concentration factors due to dishing of the head.

scholarly journals Studying Inertia Effects in Open Channel Flow Using Saint-Venant Equations

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1652
Author(s):  
Dong-Sin Shih ◽  
Gour-Tsyh Yeh
Keyword(s):  
Stokes Equations ◽  
Field Application ◽  
Benchmark Problems ◽  
Algebraic Equations ◽  
Step Size ◽  
Time Step ◽  
Cross Sectional ◽  
Inertia Effects ◽  
Time Step Size ◽  
Saint Venant Equations

One-dimensional (1D) Saint-Venant equations, which originated from the Navier–Stokes equations, are usually applied to express the transient stream flow. The governing equation is based on the mass continuity and momentum equivalence. Its momentum equation, partially comprising the inertia, pressure, gravity, and friction-induced momentum loss terms, can be expressed as kinematic wave (KIW), diffusion wave (DIW), and fully dynamic wave (DYW) flow. In this study, the method of characteristics (MOCs) is used for solving the diagonalized Saint-Venant equations. A computer model, CAMP1DF, including KIW, DIW, and DYW approximations, is developed. Benchmark problems from MacDonald et al. (1997) are examined to study the accuracy of the CAMP1DF model. The simulations revealed that CAMP1DF can simulate almost identical results that are valid for various fluvial conditions. The proposed scheme that not only allows a large time step size but also solves half of the simultaneous algebraic equations. Simulations of accuracy and efficiency are both improved. Based on the physical relevance, the simulations clearly showed that the DYW approximation has the best performance, whereas the KIW approximation results in the largest errors. Moreover, the field non-prismatic case of the Zhuoshui River in central Taiwan is studied. The simulations indicate that the DYW approach does not ensure achievement of a better simulation result than the other two approximations. The investigated cross-sectional geometries play an important role in stream routing. Because of the consideration of the acceleration terms, the simulated hydrograph of a DYW reveals more physical characteristics, particularly regarding the raising and recession of limbs. Note that the KIW does not require assignment of a downstream boundary condition, making it more convenient for field application.

On Some Factors Affecting Casing Collapse Resistance under External Pressure

2020 ◽  
Author(s):  
Bisen Lin ◽  
David Coe ◽  
Richard Harris ◽  
Timothy Thomas
Keyword(s):  
External Pressure ◽  
Factors Affecting ◽  
Collapse Resistance ◽  
Casing Collapse

scholarly journals Effect of carboxylic group on the compatibility with retarder and the retarding side effect of the fluid loss control additive used in oil well cement

2018 ◽  
Vol 5 (9) ◽  
pp. 180490 ◽  
Author(s):  
Shenglai Guo ◽  
Yao Lu ◽  
Yuhuan Bu ◽  
Benlin Li
Keyword(s):  
Carboxylic Acid ◽  
Side Effect ◽  
Great Influence ◽  
Acid Group ◽  
Field Application ◽  
Fluid Loss ◽  
Oil Well ◽  
Oil Well Cement ◽  
Well Cement ◽  
Loss Control

The retarding side effect and the compatibility with other additives are the main problems that limit the field application of the synthesized fluid loss control additive (FLCA). The effect of the type and content of carboxylic acid groups on the retarding side effect of FLCA and the compatibility between FLCA and the retarder AMPS-IA synthesized using 2-acrylamido-2-methyl propane sulfonic acid (AMPS) and itaconic acid (IA) was studied in this paper. The type and content of carboxylic acid group have a great influence on the fluid loss control ability, the compatibility with retarder and the retarding side effect of FLCA. FLCA containing IA or maleic acid (MA) shows better compatibility with retarder than FLCA containing acrylic acid, but the retarding side effect of FLCA containing MA is weaker than that of FLCA containing IA. Thus, MA is the most suitable monomer for synthesizing FLCA having good compatibility with retarder AMPS-IA.

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