An operator offshore Qatar had been forced to shut in a gas lift well because of high pressure in the 9⅝-in × 13⅜-in annulus. A leak was suspected in the 9⅝-in casing, somewhere between 3,000 ft and 5,000 ft, but an ultrasonic imager log eliminated that possibility, showing only minor corrosion at about 500 ft.
Subsequent testing identified a leaking seal on the 9⅝-in casing hanger in the wellhead. With the casing integrity compromised, the conventional solution was to sidetrack, run a new 9⅝-in string, and install a new seal. The operator wanted to avoid this expensive option.
The alternative was to cut the 9⅝-in casing above the top of cement, pull out the cut section together with the casing hanger, replace the faulty seal, and reestablish casing integrity to surface. Any remedial solution had to be gas-tight for the planned 2,000-psi injection pressure and robust enough to last for the life of the well.
SLB proposed its Casing Reconnect metal-to-metal, gas-tight casing repair system, an ISO 14310 V0-rated, full-axial-load-bearing reconnection solution that uses proprietary sealing and anchoring technology. The 9⅝-in system delivers a connection with
The casing was cut at 647 ft—below the corrosion depth—and the cut string was pulled out together with the casing hanger. The faulty seal was replaced and subsequently, 13 replacement casing joints were run in with three pup joints for space-out and the Casing Reconnect system receptacle on the bottom. The casing hanger and landing string were made up and the casing hanger was landed in the wellhead; the bottom of the string was at 660 ft, with the pup joints providing 13 ft of casing stump swallow.
The expansion tool and a downhole hydraulics module (DHM) were run in on drillpipe. Once the tool was in position, surface pressure was gradually increased to 4,439 psi and multiplied downhole by the DHM. The casing stump was hydraulically expanded into the receptacle of the Casing Reconnect system to rejoin the two strings with a high-axial-load-bearing, metal-to-metal, gas-tight seal.
A 500-psi low-pressure test was conducted to check casing integrity before pulling the expansion tool out of the well. The entire operation was executed smoothly with zero NPT. Subsequently, the 9⅝-in casing was pressure tested to 2,500 psi for 30 min, confirming well integrity and eliminating the need to sidetrack.
