Float Equipment
Float equipment refers to the back-pressure check valve components installed at the bottom of the casing string for cementing operations. Float equipment serves two functions: guiding the casing into the wellbore and preventing cement from flowing back up the inside of the casing after displacement — a phenomenon called U-tube that would contaminate the cement slurry above the float collar.
What Float Equipment Does
During cementing, cement slurry is pumped down the inside of the casing string, out through the float shoe at the bottom, and up the casing-formation annulus. When cement pumping stops, the hydrostatic pressure of the cement column in the annulus is higher than the column of mud inside the casing — creating a U-tube effect that would push cement back up into the casing.
The float shoe and float collar contain one-way check valves — typically spring-loaded or flapper type — that prevent this back-flow. The result is that cement remains in the annulus where it was placed and begins to set without contamination.
Product Range — Vulcan PROBE™
Float Shoes
The float shoe is the bottom-most element of the casing string. It guides the casing into the wellbore, provides a nose for running through tight spots, and contains the primary back-pressure check valve. The PROBE™ float shoe is available in a range of configurations for different wellbore conditions.
Float Collars
The float collar is installed one or two joints above the float shoe. It contains a second check valve and provides the landing point for cementing plugs — the bottom plug lands on the float collar before displacement, followed by the top plug which signals the end of cement pumping. The space between the float collar and float shoe (the shoe track) captures any contaminated cement and drilling fluid at the end of displacement.
Guide Shoes
Guide shoes are open-end devices with no check valve — they guide the casing into the wellbore without providing back-pressure prevention. Used in applications where the cement design does not require float valve back-pressure protection, or as an inner string guide.
Auto-Fill Float Equipment
Auto-fill float equipment allows the casing string to fill automatically with wellbore fluid as it is run into the hole — eliminating the need to pump fill on the way in. The auto-fill feature deactivates when the cementing plug contacts it, after which it functions as a standard check valve. Used to reduce casing running time and eliminate differential fill-up pressure concerns.
Key Specifications
| Parameter | Details |
|---|---|
| — | — |
| Casing sizes | 4½” – 20″ |
| Check valve types | Spring-loaded ball, flapper |
| Auto-fill | Available — deactivates on plug contact |
| Material | Steel body with cement or resin-impregnated fill |
| Standard | API 10D, API 11D |
Why Source Through Proxima
Proxima supplies Vulcan PROBE™ float equipment as part of a complete casing running and cementing package — matched to your casing size, cementing design, and wellbore conditions.
Frequently Asked Questions
Q: What is the difference between a float shoe and a float collar?
The float shoe is at the very bottom of the casing string and guides the casing into the wellbore. The float collar is one or two joints above and provides the cement plug landing seat. Both contain check valves. Together they define the shoe track — the section that captures end-of-displacement contaminated fluid.
Q: When should I use auto-fill float equipment?
Use auto-fill when running long casing strings or running casing in a well with low fracture gradient where fill-up pressure could cause formation damage. Auto-fill eliminates the need to pump fill on the way in and reduces the risk of differential sticking.
Q: How does the cementing plug interact with the float collar?
The bottom cementing plug is released ahead of the cement slurry to wipe the casing clean of drilling fluid. It lands on the float collar, ruptures under pump pressure, and cement flows through into the annulus. When cement displacement is complete, the top plug lands on the bottom plug and pump pressure rises sharply — the signal that displacement is complete.
