Objective: Freeze casing to install primary seal on intermediate casing.
Well Information: 51 mPa Bottom hole pressure. Failed cement job was allowing pressure to surface on intermediate casing side where there was no primary seal installed. Invert mud was being pushed thru failed cement to surface.
Procedure: Fresh water was pumped to push invert down away from surface. One cube of drilling mud was then pumped to ensure area to be frozen was clear of invert. Freeze gel was then pumped down surface, intermediate and productions casing. Dry ice was applied and freeze was held for 24 hours and pressure tested. Freeze plug tested OK. Drilling rig was then rigged out. Freeze was then held for another 48 hours. Crane was then brought in and drilling rigs BOP stack was removed. Primary seals were then installed in casing. 7 1/16” Gate valve and 70 mPa stack were installed and pressure tested. Well was turned over to rig crew for thawing operations.
Time on location: 5 days of 24 hour operations.