MULTI FUNCTION CIRCULATING TOOL 

MULTI FUNCTION CIRCULATING TOOL 

Multi Function Circulating Tool (MFCT), Clutch Type, has been developed for use in wells 

where high circulation rates are required at various times to displace solids out of the hole. It allows 

flow rates to be boosted at a liner top to increase the annular velocity of the wellbore fluid, thereby 

increasing the cleaning action. It also allows the spotting of chemical pills and the change-out of 

wellbore fluids to be carried out very efficiently. The tool is particularly suited to wells with small 

liner diameters in which well clean-up operations are performed prior to running completions or test 

strings. The tool can be run when drilling cement and milling/polishing liner top PBRs. 

The Clutch Type MFCT gives the benefit of pipe rotation and circulation above a liner with the ports 

open, whilst protecting the lower string from potentially damaging torque. When the tool is open, 

only the drill string above the tool is rotated. When the tool is closed, the complete string can be 

rotated with circulation directed through the bit or mill. 

The tool does not require darts or balls to be pumped down the drill pipe and can be operated in the 

hole as many times as required by simply slacking off or picking up the string. 

The tool is also available with an integral Shut Off Plug as an option. When fitted with this plug, all 

flow is directed through the ports when the tool is open and the flow path to the string below is 

positively shut off. 

Operation 

The tool is operated in a similar fashion to a bumper sub used during drilling. It has a stroke length 

of 15 inches. Running in the hole the tool is fully stroked out and any circulation goes through the 

end of the drill string. Rotating torque is transmitted to the whole drill string (clutch engaged). The 

tool has a shear ring installed (7,000 lbs (standard) 15,000 lbs, 20,000 lbs, 30,000 lbs or 40,000 lbs in the 

3.1/2” IF tool and 20,000 lbs (standard), 7,000 lbs, 30,000 lbs, 40,000 lbs or 60,000 lbs in the 4.1/2” IF 

tool) to prevent premature opening whilst running in hole or drilling. 

The MFCT is run with a suitable ‘no-go’ device (liner top dressing mill, bearing sub or stabiliser) 

below it so that the tool can be operated without putting the lower string in compression. When this 

device lands on the liner top and the required weight is slacked off, the outer sleeve moves down 

opening the fluid by-pass channel. The tool is now open and high circulating rates can be achieved 

through the circulating ports. Rotating torque is not transmitted below the tool in this position 

(clutch disengaged). 

Circulation is restored through the end of the drill string by simply picking up weight and moving 

the outer sleeve up. The open and shut cycle can be performed as many times as required without 

the need for expensive trips out of the hole and the driller has immediate positive control of the 

circulation route. 

To avoid seal damage, the tool should not be opened or closed when there is flow through it. The 

pumps should be switched off and the tool operated only after returns have stopped. In addition, to 

avoid damaging the clutch mechanism, the drill string should also not be rotated, or have any 

residual torque, when functioning the tool.