A New OCTG Strength Equation for Collapse Under Combined Loads
- Frans J. Klever (Shell Intl. E&P BV) | Toshitaka Tamano (Kogakuin University)
- Document ID
- Society of Petroleum Engineers
- SPE Drilling & Completion
- Publication Date
- September 2006
- Document Type
- Journal Paper
- 164 - 179
- 2006. Society of Petroleum Engineers
- 4.1.5 Processing Equipment, 4.1.2 Separation and Treating, 4.2 Pipelines, Flowlines and Risers, 1.7.5 Well Control, 1.14.1 Casing Design, 1.7.2 Managed Pressure Drilling, 1.10 Drilling Equipment, 1.6 Drilling Operations, 4.6 Natural Gas, 1.7.1 Underbalanced Drilling
- 30 in the last 30 days
- 1,010 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 10.00|
|SPE Non-Member Price:||USD 30.00|
Wells are becoming more challenging, and casing designers are faced with increasing design pressures. Deep hydrocarbon targets lead to requirements for the casing to resist collapse under external pressure, while significant internal pressure and axial compression or tension may exist at the same time.
This paper describes the development, and its evaluation, of a new collapse-strength equation for oil-country tubular goods (OCTG). It is based on a generalization of a model previously proposed by Tamano et al. (1983). The new model is evaluated through comparisons with both finite-element analyses(FEAs) and test data. It is more accurate in dealing with combined internal pressure, external pressure, and axial load than, for example, the model currently provided in American Petroleum Inst. (API) Bull. 5C3 (1994).
The joint API/Intl. Standardization Organization (ISO) subcommittee (SC)5 Work Group (WG) 2B tasked with modernizing the Bull. 5C3 property equations has evaluated a number of collapse models available in the literature on their performance against several collapse databases. As a result, the model presented here is recommended for developing design collapse strengths in the new ISO TR 10400 standard (2006).
The design-collapse-strength equations currently used in the industry and provided in Bull. 5C3(1994) give a highly nonuniform failure probability over diameter, weight, and grade for downhole well tubulars (Adams et al. 2003; Ju et al. 1998). In addition, the Bull. 5C3 average collapse-strength equations are relatively poor predictors of true collapse and, therefore, no compelling case exists to use these equations for qualifying high-collapse pipe and other proprietary products. Designing deep wells is becoming more challenging because of requirements for the casing to resist collapse under external pressure while significant internal pressure and axial compression or tension may exist at the same time. This highlighted the need for revisiting the method to account for combined loading in collapse.
The situation may be improved if more accurate collapse-prediction formulas could be developed that adequately capture the physics of collapse failure, and more explicitly include the effect of imperfections. Because the collapse-failure mechanism is an instability phenomenon (i.e., the transition from an essentially round pipe to a pipe that starts to ovalize and flatten with the external-pressure capacity reaching a maximum can happen very quickly), it is not feasible to expect a simple equation to capture this failure mechanism very accurately. However, theoretical analyses, detailed FEA, and numerous collapse tests have provided a wealth of insight that has guided the development of approximate collapse equations that capture collapse failure to a satisfactory degree.
|File Size||1 MB||Number of Pages||14|
Adams, A.J., Moore, P.W., and Payne, M.L. 2003. On the Calibration of Design CollapseStrengths for Quenched and Tempered Pipe. SPEDC 18 (3):214-227. SPE-85112-PA.
Bull. 5C2. 1987. Bulletin on Performace Properties of Casing, Tubingand Drill Pipe. 20th edition. Washington, DC: API (May).
Bull. 5C3. 1994. Bulletin on Formulas and Calculations for Casing,Tubing, Drill Pipe, and Line Pipe Properties. Sixth edition Washington, DC: API(October).
Clinedinst, W.O. 1985. Collapse Resistance of Pipes. PhD dissertation,Century U., California.
Ju, G.T., Power, T.L., and Tallin, A.G. 1998. A Reliability Approach to the Designof OCTG Tubulars Against Collapse. Paper SPE 48332 presented at the SPEApplied Technology Workshop on Risk Based Design of Well Casing and Tubing, TheWoodlands, Texas, 7-8 May.
Kyriakides, S. and Yeh, M.K. 1985. Factors Affecting Pipe Collapse.Engineering Mechanics Research Report 85/1, Dept. of Aerospace Engineering andEngineering Mechanics, U. of Texas at Austin.
Needleman, A. and Tvergaard, V. 1977. Necking of BiaxiallyStretched Elastic-Plastic Circular Plates. J. Mech. Phys. Solids 25: 159-183.
Pattillo, P.D. and Huang, N.C. 1982. The Effect of Axial Load on CasingCollapse. JPT 34 (1): 159-164. SPE-9327-PA.
Pattillo, P.D., Last, N.C., and Asbill, W.T. 2004. Effect of Nonuniform Loading onConventional Casing Collapse Resistance. SPEDC 19 (3):156-163. SPE-79871-PA.
Tamano, T., Mimaki, T., and Yanagimoto, S. 1983. A New Empirical Formula forCollapse Resistance of Commercial Casing. J. of Energy ResourceTechnology: 489-4985.
Timoshenko, S. 1936. Theory of Elastic Stability. First edition.222-224. Columbus, Ohio: McGraw-Hill.
TR 10400. 2006. Petroleum and Natural Gas Industries—Formulas andCalculations for the Properties of Casing, Tubing, Drill Pipe and Line PipeUsed as Casing or Tubing. Geneva: ISO.
Triantafyllidis, N. and Kwon, Y.J. 1987. Thickness Effects on theStability of Thin Walled Structures. J. Mech. Phys. Solids35 (5): 643-674.
van den Berg, G. 1995. A Finite Strain Shell Model for the Analysis ofModerately Thick-Walled Tubes. PhD thesis, Delft U. Press.