Flow-control accessories add to the flexibility of the cased-hole completion design and perform a multitude of tasks, such as:
- Temporarily plugging off the tubing string.
- Establishing temporary communication between the tubing and the annulus.
Profile seating nipples and sliding sleeves have a special locking groove and a honed sealbore to allow a flowcontrol device to lock in the nipple and seal off when installed. By design, the sleeves and nipples will have a smaller inside diameter (ID) than that of the tubing string. For this reason, careful consideration must be given to the overall application and completion design when selecting and sizing the various models of profile seating nipples and sleeves. This is especially true in any case in which through-tubing operations or perforating are planned.
Correct application of flow-control accessories can greatly reduce the time and money spent on diagnosing well problems (such as tubing or leaks) should they occur. Strategically placed profile seating nipples above and below the packer aid in isolating the leak to the packer or the tubing string. Once the source of the failure is known, a plan can be formulated to resolve the problem. Not much can be done to fix a packer leak without well intervention. However, special flow-control devices are available to straddle across sections of leaking tubing and deter work overs. In either case, the knowledge gained by being able to use flow-control accessories and devices to perform downhole diagnostics is extremely valuable in planning corrective action to be addressed in the subsequent work over.