Circulation subs

“BURINTEKH”, Ltd circulation subs allow repeatedly switch the fluid flow from the inner space of the drill string to the annulus bypassing the BHA elements located below the valve.

The circulation sub is activated by dropping the activation ball.

To deactivate the device it is necessary to throw two steel deactivation balls into the drill pipes, reaching the device blocking the flushing ports under the action of the fluid flow. The mud pump continues to work, the pressure increases, the device is deactivated - the activation ball is cut off through the seat while the central channel opens, the side flushing holes are closed. The circulation sub is moved to its original transport position.

Application:

• Pumping plugging materials;
• Acid treatment;
• Mud displacement;
• Borehole cleaning;
• Annular velocity improvement;
• Low wall cuttings transportation.

BIT-PC-108.01

Device with OD 108 mm.
Having two flushing holes with a diameter of 15 mm each, the device allows pumping a bridging agent with a fraction size of up to 5±1 mm.
The circulation sub allows operating with a flow rate up to 12 l/s.

BIT-PC-120.02

Device with OD 120 mm.
Having two flushing holes with a diameter of 21 mm each, the device allows pumping a bridging agent with a fraction size of up to 7±1 mm.
The circulation sub allows operating with a flow rate up to up to 20 l/s.

BIT-PC-172.01

Device with OD 172 mm.
Having two flushing holes with a diameter of 33 mm each, the device allows pumping a bridging agent with a fraction size of up to 11±1 mm.
The circulation sub allows operating with a flow rate up to up to 40 l/s.

Technological characteristics:

The exclusive feature of the device is that the circulation ports are closed when the mud pump is stopped. This feature eliminates mud backflow from the annulus into the drill string.