Negative Operational LL with DNO

Oselvar (A-1 H, A-2 H, A-3 HT2) – P&A

What happened:

Initially believed that we did not get a good pressure test (Formation Integrity Test). Suspected failure could be because we were not able to keep the swab cups out of the perforated interval. Was later confirmed OK so no issues.

What was planned:

Place swab cups over perforations in casing, isolate same. Pressure up between swab cups and pressure test against formation. Annulus Integrity Tool from HydraWell.

What was learned:

A spacing of 2 m between the inner swab cups is not ideal when trying to cover a 91 cm perforation on a floater. The rigs crew are not able to provide vertical depth accuracy to operate the string up/down less than 50 cm increments. Pipe stretch, tide and rig heave impact this.

What actions are required:

If possible, increase spacing to 4 m between swab cups for use on semi-submersible rigs and well depths over 3000 mMD. Spacing can be increased to 4 m (Verified by Hydrawell).