Positioned at the uppermost point of the pressure control equipment string, the NOV Elmar Enviro™ Grease Injection Control Head comprises two major sub-assemblies, the Enviro™ Combination Stuffing Box and Line Wiper and the Flotube Assembly.
The hydraulic stuffing box is designed to pack-off on a stationary wireline by means of a pack-off rubber, the hydraulic line wiper will wipe excess grease from a moving wireline.
Two types of flotube assemblies are available, the "solid” type and the “concentric” type, as described in this data sheet. The concentric flotube assembly is made up of an inner flotube sized to fit tightly around the wireline and an outer sleeve to support the assembly.
To prepare for operations, the wireline is threaded through the components of the NOV Elmar Enviro™ Grease Injection Control Head before the rope socket and wireline head are made-up.
When entering a well under pressure, viscous grease is injected into the flotubes at a pressure greater than the existing well pressure. The grease fills the annular space between the inner wall of the flotube and the outside surface of the wireline, forming a liquid seal that contains the well fluids while allowing wireline movement.
The NOV Elmar Enviro™ Grease Injection Control Head is supplied with a pin threaded connection on bottom and a wire tulip guide on top.
When changing line size, a different line size kit is needed for the Enviro™ Combination Stuffing Box and Line Wiper.
Recommended flotube clearance + 0.003" to 0.008".
The bottom connection can be mated to a quick-union, or a ball check valve/tool catcher combination.