A cementing head is a manifold system mounted on top of the casing that pumps cement slurry from the cement unit into any type of casing string. The cement head is also used to release the top and bottom cement plugs.
Depending on the type of casing cementing operation, the "cement head" is threaded into the top casing collar or connection sub. The discharge side of the downhole pump is connected to the cement head by a series of hinged or straight sections of high-pressure steel pipes, also known as "handling irons"
Application of cementing head
The cement head connects the discharge line of the cement unit to the top of the casing (Figure 1). This unit is designed to hold cement plugs used in conventional primary cementing operations. The cement head releases the bottom cement plug, mixes and pumps the calculated slurry volume, releases the top plug and displaces the cement without making or breaking the connection to the top of the casing. For ease of operation, the cement head should be installed as close to the drill floor as possible. If the cement plugs are installed in the correct sequence or are not released from the cement head, the cementing operation will not be successful.
Mud is often used to replace grout. Cement pumps or rig mud pumps can be used for displacement. It is recommended to displace the grout at the highest possible rate. High rate displacement will facilitate efficient mud displacement. Since grout is very viscous and has such a high density (cement properties), it is unlikely that turbulent flow will be achieved in the grout. However, turbulent flow may be created in the isolator, which will result in more efficient mud displacement.