Freeze and Hot Tap Case History #31
Objective: Freeze well below coil tubing b.o.ps in order to remove damaged 2 inch coil tubing in lubricator and re-attach to good coil tubing.
Well Information: 20 mpa sweet gas well with frac tool,overshot,jars, and crossover to 2 inch coil tubing stuck across master valves and coil tubing b.o.ps. Stack configuration from bottom to top consisting of two 4 1/16 master valves, flow cross with two 2 in wing valves, two foot 4 1/16 10,000 psi spool, 4 1/16 flow cross with one outlet and valve, quad coil tubing b.o.ps and twenty ft of 4 1/16 lubricator attached to injector.
Procedure: Build cribbing between bottom flow tee and upper flow tee on 2ft spool below b.o.ps. Pump freeze gel into lower and upper flow tees add ice to cribbing. Maintained ice and monitored pressure throughout evening. Wrapped steam line on lubricator to keep thawed, and kept heat on above freeze plug to allow access for pumping to pressure test and monitor. Pressure test with nitrogen to 30 mpa on top of freeze plug, do negative test and monitor for venting. Remove lubricator from top of coil tubing b.o.ps and lifted 3 ft exposing damaged coil and crossover to the jars-found that coil was collapsed from crossover to the top of the lubricators. Performed hot tap on coil just below injector pack-off as this was the closest good tubing to attach hot tap clamp. Confirmed no pressure in coil before cutting damaged coil above crossover. Re-positioned lubricator, ran out all flattened coil and cut off. Installed crimp on coil connector on good coil. Replaced crossover above jars then re positioned lubricators and reattached the good coil to the crossover, lowered lubricator and re-secured. Pressure test all connections against freeze plug with nitrogen. Removed ice and cribbing, kept positive pressure above freeze plug and handed well over to coil tubing operations for thawing.
Time on location: 36 hours.