Freeze wellhead to replace malfunctioning top section valve.
Well Information: 5,000kPa sweet gas well with malfunctioning master valve.
Procedure: Install cribbing and dry ice. Install pumping equipment and pressure test. Inject gel into tubing and freeze across tubing hanger. Pressure test ice plug, replace top section. Pressure test top section, maintain pressure above plug, and thaw.
Time on location: 11 hours