Page 118 - Well Control for Completions and Interventions

110 Well Control for Completions and Interventions

Figure 3.19 Formation saver valve (FSV). Source: Photo courtesy of Precision
Oiltools Ltd.

has been installed, the barrier is opened allowing the well to produce.
Most valves open following a predetermined number of pressure cycles.
This eliminates the need for mechanical intervention. Having a mechanical
barrier undoubtedly reduces the possibility of losses (and therefore a kick)
during completion operations. However, there are some issues potential
problems associated with these valves.
• Debris can accumulate on top of the valve, preventing it from open-
ing. Keeping the wellbore clean and performing a dedicated clean out
trip is essential.
• There have been incidents where the valves have been opened inad-
vertently. On one occasion a valve was mechanically opened after the
tail-pipe of a wellbore cleaning work string caught on the mechanical
shifting profile in the body of the loss control valve. The fluid in the
casing was underbalanced and the well kicked. On other occasions,
poor record keeping on pressure cycles has resulted in the valves open-
ing unexpectedly.
In spite of these problems, having a barrier in the well is a good thing
and one to be recommended, mainly because of well control considera-
tions, but also because of reduced formation damage (Fig. 3.19).

3.8 LANDING NIPPLE

A locating nipple or landing nipple allows a range of wireline (or
coiled tubing) conveyed tools to locate and, where necessary, seal inside
the tubing string. A nipple is a short length of heavy wall tubing
machined with an internal profile that will receive and secure a lock