Summary
This paper describes the material and form factors that control pipe
expandability, the influence of axial restraint during expansion on pipe
expandability, and the post-expansion collapse resistance of solid expandable
tubulars. Of the various properties required for the pipe used in an
expandable-tubular system, the most important are pipe expandability and
collapse resistance. Therefore, clarification of the factors that control pipe
expandability and development of a reliable technique to predict pipe-collapse
resistance should be useful for the design of casings that use expandable
tubulars.
These tasks were tackled as follows. First, two types of pipe were evaluated
by use of a pipe expander that is capable of imposing an axial restraint on the
pipe. Next, to prepare a design diagram for pipe expandability, a numerical
analysis was carried out by use of the finite-element method (FEM). In
addition, a full-scale collapse test was carried out to compare the collapse
resistance of the two types of pipe. Then, the validity of two techniques for
predicting the collapse resistance of expanded pipe--FEM model and conventional
formula--was determined.
The results of the research revealed the appropriate combination of pipe
form and mechanical properties that can prevent pipe from breaking because of
expansion. In addition, the expandability of the pipe decreases markedly under
an axial restraint imposed on the pipe during expansion. In addition, it is
possible to accurately predict the collapse resistance of pipe after expansion
by use of an FEM simulation. Furthermore, by modifying the definitions for pipe
mechanical properties, it was also discovered that the collapse-prediction
formula can be used to accurately predict the collapse resistance of pipe after
expansion.
The study results will deepen the understanding of the expandability and
collapse of expandable tubular pipes and provide basic data for improving the
reliability of casing designs that call for expandable tubulars.
© 2012. Society of Petroleum Engineers
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History
- Original manuscript received:
3 August 2011
- Meeting paper published:
1 March 2011
- Revised manuscript received:
7 June 2012
- Manuscript approved:
11 September 2012
- Published online:
28 December 2012