Objective: Replace split 4 by 2 inch swedge below master valve on a coil tubing completion.
Well Information: Well gas blowing out of swedge that is split vertically from threads to top of the neck and split horizontally half way around neck. Shut in casing and tubing pressure is 7 mPa, flowing pressure of 3.5 mPa. Casing size of 4 ½ inches with 1800 meters of 2 inch coil tubing landed in coil tubing hanger above 4 ½ demco valve and below 4 by 2 inch swedge with 2 inch master valve. No vehicle access, temperatures ranging from minus 20 degrees centigrade to minus 30 degrees.
Procedure: All personnel and equipment were flown into location from staging area. A small shelter using scaffolding, tarps and Herman nelson heater erected for purpose of shelter and keeping lubricators of freeze gel, pumping equipment and water needed for pumping purposes thawed. Installed a dog collar around the vertical crack of the damaged swedge to keep from blowing out sideways and chained top of swedge to bottom of demco valve to keep from blowing off from the top. Cribbing for dry ice was built between demco valve and damaged swedge on the coil tubing hanger and connecting nipple. Casing was left flowing to compressor station to lessen stress on damaged swedge. A mixture of freeze gel and sealing material were pumped into the coil tubing through side wing valve on the flow line using portable lubricators with wiper plugs and gas powered pressure washer. Once flow of gas was sealed sufficient gel was pumped to ensure that freeze plug would form where cribbing was built. Maintained dry ice and monitored pressures through evening. Intrinsically safe heat tape powered by portable gen-set was used to keep pumping areas and equipment to be changed from freezing. In a.m. pressure test revealed freeze plug was not holding. Flowed out failed freeze plug, swedge remained sealed. Moved cribbing down below demco valve, shut in casing , pumped sufficient freeze gel into 4 ½ casing and down 2 inch coil to form freeze plug in the area of the cribbing using the methods mentioned above. Maintained ice and monitored pressure through the evening. In morning performed positive pressure test of 12 mPa using baker pump on freeze plug and a negative test. Damaged swedge was removed and new swedge with new master valve installed. New equipment was pressure tested using baker pump. Well was thawed using Herman nelson heaters with sufficient duct tubing to keep ignition source away from well. The freeze plug was then flowed out and the well was then tied back into the production flow lines. All equipment and personnel were then flown back to staging area.
Time on location: 3 days-due partly to helicopter restrictions and cold weather problems.