Slot recovery in deepwater GOM field
In a redevelopment and slot recovery operation in a subsea well in the mature Green Canyon field, Gulf of Mexico (GOM), an operator needed to P&A the nonproducing lower wellbore, sidetrack a new wellbore from the recovered slot, and use the existing subsea infrastructure to return the well to production. To maximize the economics of the slot recovery, the operator sought technology to reduce the number of trips needed to cut, circulate, and retrieve wellhead seals and casing.
Conventional methods require at least three trips or more if the casing cut and pull is unsuccessful after the first cut. Wellhead seals are recovered on the first trip. Then, the pipe cutter is run in on the second trip. On the third trip, the inline casing spear is run in, and the severed pipe is circulated up the annulus for recovery before the whipstock can be set.
Fewer trips with ProCISE system
For this slot recovery operation, Schlumberger recommended the ProCISE casing cutting and recovery system, which is an engineered assembly composed of multiple technologies designed to perform the P&A operation more efficiently. Prior to initiating a cut, the wellhead seals are pulled and mud displacement circulates out trapped annular gas. An inline casing spear is then engaged and an overpull check is performed to indicate a secure latch and to cut the casing in tension. Next, the WELL COMMANDER circulating tool from M-I SWACO, a Schlumberger company, is deactivated. Then circulation begins, transmitting rotation to the cutting assembly.
The multicycle pipe cutter, which allows multiple cuts per run, provides a contingency cutting system when multiple cut attempts are required, a common occurrence in P&A operations. In this well, imaging data showed settling of solids at the cutting location, which could require multiple cuts. The pipe cutter has three sets of blades that can perform multiple cuts in one trip, so if the casing cannot be freed on the first attempt, the cutting process can be repeated further up until the casing string is freed.
The pipe cutter is also equipped with a Flo-Tel downhole mechanical position indicator that provides pressure data at the surface for confirmation of a successful cut at each cutter position, eliminating the risk of pulling out of hole before the cutting operation is complete.