The Well Casing Centralizers

Well casing centralizers work in the annular space of a well casing and are a critical tool for achieving proper well casing alignment. They are typically made of corrosion-resistant injection-molded plastic and come in two sizes. The first size is designed to fit a wellbore diameter up to a maximum of 5.5 feet and the second size is designed for wellbore diameters greater than 6.5 feet. Both types are adjustable and require two separate segments to achieve proper axial positioning.

A composite casing centralizer has a bow-spring design that is designed to provide a restoring force to the casing when the bow is contacted. The amount of force applied to the bow is a function of the spring bow's compression and restoring force, which can vary depending on the type of centralizer used. The type of centralizer selected will depend on the desired standoff distance and casing design.

Centralizers with large bow heights have several disadvantages. A large bow height increases the force exerted by the spring bow when pressed inward toward the casing. Additionally, a large bow height requires a large compressive force in order to deflect it close enough to the casing to allow insertion into the wellbore. Because casing string openings are usually smaller than the openings of well casing centralizers, this type of centralizer can cause difficulty when lowering the casing string.

A centralizer according to the present invention is shown in Figs. 2 and 3. The centralizer 10 comprises two end collars 12 and a contact angle reduction member 18 on both ends. These parts are partially inserted into the borehole 20. Further progression of the centralizer and casing is illustrated in Fig. 3. The contact angle reduction member is then moved on the upper edge of the borehole, ensuring a smoother casing insertion.

An alternative embodiment of a well casing centralizer comprises a sleeve bearing that is interposed between the centralizer end bands and the casing. This bearing is adapted to rotate with the casing, thereby promoting even wear over its bearing surface. The sleeve bearing may also have radially extending end flanges.

The centering force requirement of a centralizer requires a substantial amount of spring bow material, a high number of springs, and a profile that has the spring bows pointing outwards. This type of centralizer is particularly challenging to insert into the wellbore, because its spring bows engage with the wellbore wall and create substantial resistance.

Casing centralizers are important pieces of equipment for controlling a well. Properly installed casing anchors the well. This helps in controlling a well and preventing potential flow zones and corrosive formation fluids from reaching the surface. Additionally, they prevent vertical migration of gases that are trapped behind the pipe. Check out this post for more details related to this article: https://en.wikipedia.org/wiki/Cementing_equipment.