A casing head has many other names: casing bowl, a-section, Braden head, or starting head. The casing head is the surface pressure control equipment’s primary interface. These interfaces would be blowout preventers for well drilling or the Christmas tree for production wells.
The casing head is often welded or screwed on the top of the conductor pipe, and the casing then becomes a part of the wellhead system of the oil well. It serves as an adapter between the first casing string and the BOP stack (during drilling) or the wellhead (after drilling has been completed). The casing head uses a flanged or clamped connection to match what the BOP stack or wellhead needs.
Types of Casing Head
There are two major types of casing head design.
Thread Type Casing–This is a casing head housing design that features a 45-degree landing shoulder. This type of design prevents damage to sealing areas caused by drilling tools and avoids test plug and blow protector wedging problems when applying pressure. This design also allows for the accurate vertical positioning of annular seals, control line ports, and test ports.
Slip Type Casing–head eliminates post-heating, saves time, and is quick to install. It is well suited for exploratory drilling because It can be moved from well to well, eliminating the extra transportation and repair charges associated with conventional welded heads. Installation of slip type casing is simpler as well.
A casing head is an adapter between the first casing string and either the BOP stack (during drilling) or the wellhead (after completion). This adapter may be threaded or welded onto the casing, and may have a flanged or clamped connection to match the BOP stack or wellhead. It is the primary interface for the pressure control equipment. When installed, a casing head is typically tested to stringent pressure and leak-off parameters to ensure viability under blowout conditions before any surface equipment is installed.
Casing Head Functions
The casing head is an essential component of any wellhead system. It provides many different vital functions within the system. These functions include:
The casing head in a conventional wellhead system is the lowest part of the wellhead assembly and is almost always connected to the surface casing string. It supports the remaining parts of the wellhead and completion equipment. The casing head performs the following functions:
- Provides a base to attach the surface casing string.
- Supports or transfers the weight of the equipment during drilling and well servicing operations
- Provides a platform for testing the blowout preventers (BOP) while drilling
- Isolates the inside of the surface casing from the outside environment
- Provides outlets for fluid returns
- May serve as a test port to test welded or other non-threaded bottom casing head connections
- Allows the suspension and packing off of the next casing string
Forged Components Delivers Superior Quality Casing Heads and Other Wellhead Components
FCI is one of the world’s premier wellhead component manufacturers providing superior quality casing heads, tubing heads, and goat heads. For more information, please call us at (281) 441-4088 or contact us online to get in touch with one of our sales personnel today.