Pressure loads (burst and collapse)

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The burst and collapse loads are calculated by taking the difference (Pi-Pe) between the internal and external pressure profiles for each load case.

If the resulting load line is mainly positive, it is called a burst load line (BLL); if it is mainly negative it is called a collapse load line (CLL). The net pressures (positive or negative) are then compared with the API burst or collapse ratings of the casing.

Collapse or burst loading can occur during drilling and production.

Internal Profile

When considering an internal pressure profile (burst or collapse) in the drilling phase, only one situation need be taken into account.

In the production phase, a distinction is made between the internal pressure profiles above and below the packer.

When considering the internal pressure profile for burst in the production phase, a further distinction must be made according to the type of well involved: production well or injection well.

External Profile

When considering an external pressure profile, two factors need to be taken into account:

  • the quality of the cement column between the casing and the formation (which determines the extent to which reservoir pressures are passed on to the casing)
  • the quality of the fluid in the annulus between casing and formation above the top of cement.

Note: Deterioration of this fluid in the course of time can lead to a drop in its density, and hence to a steeper external pressure profile and higher annulus pressures. In this context, it is importan to distinguish between exploration wells (wshort life) and development wells (long life).

Comments  

#2 sudheer 2015-04-23 06:15
i need the equations about calculating burst and collapse pressure of the casing
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#1 abdalqadr 2015-02-12 11:18
i need the equations about calculating burst and collapse pressure of the casing


Regards
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