Float Collar, Casing Centralizer & Other Cement Floating Equipment

 

Float Collar, Casing Centralizer & Other Cement Floating Equipment 

Float collar and float shoe are important floating equipment in petroleum and natural gas fields. They are used to guide the casing to set in the hole and ensure the quality of cementing. They are widely used in the lower section of the well to help decrease strain on the derrick while directing packaging past edges and bog zones in the opening.

A casing centralizer is also one of the most important cement tools used in the field. Let’s have a glimpse of these tools and understand their applications:

Float Shoe

The float shoe contains a backpressure valve that prevents fluids from entering the casing while the pipe is lowered into the hole and prevents cement from flowing back into the casing after placement while enabling circulation down through the casing. The float collar includes a back pressure valve and serves basically the same function as the float shoe.

Float Collar

The float collar is run in a casing assembly, usually several joints above the float shoe. It provides a seat for the cement plugs to help top plugs shuts off the fluid flow and prevents over-displacement of the cement. The space between the float shoe and float collar provides a containment area to entrap the likely-contaminated fluids from the wiping action of the cementing plug, securing the contaminated fluid away from the shoe where a strong cement bond is of primary importance.

Casing Centralizer

A casing centralizer is a steel apparatus that is secured around the casing at different locations in the borehole to prevent it from contacting the wall. The casing centralizer is fitted with bowsprings and a hinged collar to keep the casing centralized in the borehole. There are two classes of a casing centralizer, namely, bow-spring design and rigid blade design.

It helps efficient cement placement between the casing and the bore wall preventing uneven and imperfect seals that can cause drilling fluid to be pushed up the borehole, contaminating aquifers and upper-level strata.

The bow-spring design casing centralizer is slightly larger than the wellbore, and it provides complete centralization even if the well has deviated. But in some cases, it may not be able to support the casing weight. A rigid blade design needs the wellbore to be in good condition, or it may cause trouble downhole.