Home / News / Presentation highlights expandable systems study performed in conjunction with Petrobras

A comparative study on expandable systems is being carried out by the Federal University of Rio de Janeiro in conjunction with Petrobras, with the goal of assessing the structural strength of expanded tubulars through numerical and experimental analyses, said Theodoro Antoun Netto of the university.

Discussing the study at the IADC World Drilling 2008 Conference on Wednesday, Mr Netto noted that Petrobras has installed two solid expandable tubulars and eight expandable sand screens, and some installations have not been successful. That led to the study, which seeks:

Presentation highlights expandable systems study performed in conjunction with Petrobras

  • • An appropriate choice of expansion method.
  • • Expansion of real scale pipe (solid and screen base pipe).
  • • Analysis of expansion effects on pipe geometry.
  • • Analysis of expansion effects on pipe resistance against collapse.

In an experiment with 10% expanded vs non-expanded solid pipes, collapse pressures for the expanded pipes were approximately 2,000 psi, while the non-expanded pipes averaged around 4,000 psi collapse pressure. This was about a 50% decrease in collapse pressure for pipes expanded at a 10% ratio.

Results from an experiment with base pipes were similar to the solid pipes, with about a 50% reduction in collapse pressure with a 10% expansion rate.

An experimental setup and numerical model have been developed under the study, with good correlation found between experiments and analyses. The collapse pressures of intact and expanded base pipes and solid pipes were very similar, while collapse pressures of pipes after 10% expansion was on average 50% of the collapse pressures of the original pipe for the geometry and material tested.

Different pipe and cone geometries, expansion rates and boundary conditions must be tested in future studies, Mr Netto said.

Additional details of the study discussed during this presentation will be made available to attendees of the World Drilling 2008 Conference. A web link and password for the conference proceedings will be e-mailed to registered participants approximately one week after the event.

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