Casing designs for wells in which gas-lift completions are to be installed are based upon different design load cases from standard wells. They have to be treated differently from standard wells in two respects:
- definition of the possible pressure profiles within the "live" tubing/production casing annulus (A-annulus)
- design of the intermediate casing to withstand the consequences of a leak in the production casing for subsea wells.
A-annulus pressure profiles for the production phase should be constructed, in close cooperation with the Production Technologist, for the following production-mode cases:
- kick-off;
- gas lift;
- closed in, and assuming a leaking gas lift valve;
- evacuation to unpressured injection gas.
Note that casing design for the drilling phase is based on the standard design criteria.