What is the function of wellhead casing head
The casing head of wellhead device is installed at the upper end of surface casing string. The casing head of wellhead device is used to hang casing of all layers except surface casing and wellhead components of sealing casing annular space. The main functions of wellhead casing head are as follows
1. Wellhead equipment suspends part or all weight of casing except surface casing by hanger;
2. The wellhead device is connected with the wellhead devices such as BOP;
3. The wellhead device forms a pressure seal between the inner and outer casing strings;
4. The wellhead device provides an outlet for releasing the pressure that may accumulate between two casing strings;
5. In case of emergency, wellhead equipment can pump fluid, such as kill fluid or fire extinguishing agent, into the well through the side hole of casing head;
6. Special operations: A. if the cementing quality is not good, cement can be injected into many side holes; B. during acid fracturing, pressure balance fluid can be injected from side hole.