Freeze and Hot Tap Case History #16

Objective: Freeze tubing to replace damaged master valve to gain entrance into tubing.

Well Information: 12.4MPa sour gas well shut in for several years, master valve seized.

Procedure: Heat wellhead, expose surface casing install cribbing around surface casing and fill with dry ice. Inject gel into surface casing. While frost is transferring through gel in surface casing, scaffolding is built and hot-tap equipment is rigged up. Rig up pumping equipment to production casing, pressure test and inject gel. While frost is penetrating gel in production casing, the hot-tap drill is pressure tested and a 19mm hole is drilled in the seized master valve. The drill is removed and pumping equipment installed, pressure tested, and gel is injected to the production tubing. Due to the well conditions the dry ice maintained overnight. At daylight, the plug is pressure tested, the top section is dismantled, and the new valve is installed and pressure tested. Well pressure is applied above the ice plug and turned over to the thaw crew.

Time on location: 27.5 hours