Minimize hydraulic control lines
The actuation method uses pressure cycles to shift the valve to the selected choking
position. A single dedicated hydraulic control line, operated at surface, actuates the
choke; oil- or water-based control line fluids can be used. The choke position is controlled by a specially designed J-slot indexer that
moves the choke through each position, enabling precise flow regulation and
control. A nitrogen precharge secures the choke in the desired position even after
control line pressure is bled down, ensuring that vibrations do not accidentally move
In its standard configuration, the valve has up to 11 positions—fully open, fully closed, and
nine intermediate choke positions. It can be easily adapted to specific reservoir
needs because the choke area at each position can be customized and the indexer
can be configured for the required number of positions. The valve has been supplied
in on-off, three-position, and four-position configurations, mainly to increase the
number of flow control valves dropped from one control line.
Two versions of the valve are available. The annular valve (AP) controls flow between
the annulus and tubing, while the inline valve (LP) controls flow within the tubing. The
LP version has a shroud across the choke section and a retrievable plug installed immediately below the choke section. Flow is directed into the shroud before it reenters the tubing through the choke.
Field-proven control line connections can be externally pressure tested. Both
annular and inline valves use an integrated selective nipple profile to land plugs or
packoff sleeves for isolating zones as a contingency measure.
A rugged design makes the valves suitable for severe environments with scale
deposits, erosion, and other demanding conditions. Valves are manufactured in a
variety of materials, all meeting NACE specification MR0175. Positive closure extends to TVDs greater than 12,000 ft [3,658 m].