Float collars are placed one to three joints above the guide shoe or float shoe. Float collar provide a seat for the cement plugs, the bottom plug pumped ahead of the cement and the top plug behind the full volume of slurry. Once seated, the top plug shuts off fluid flow and prevents over-displacement of the cement. The space between the float shoe and the float collar provides a containment area to entrap the likely-contaminated fluids from the wiping action of the top cementing plug, securing the contaminated fluid away from the shoe where a strong cement bond is of primary importance. Float collars include a backpressure valve and serve basically the same function as the float shoe.
Float shoes contain 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.
Float Collar And Float Shoe Features
- The Aluminum Alloys used in this product are PDC Drillable.
- Available in 5 1/2” to 20” sizes. Customized sizes are also available.
- Applications:In all applications ranging from close tolerance liners to full casing strings.
- Standard float shoe is provided with round cement nose to deflect offledges or obstructions.
- Customizable options including nose types, ports/jets, and ball deflector.
- Can be supplied either in Single Valve or in Double valve.
- Float Collar&Shoe Specification
Float Collars And Float Shoe Specification
The manufacturing of Float Collars And Float Shoes
Question:In primary single stage cementing, why do we need a float collar, hence float shoe is also performing the same job.
Answer: (1)The main purpose of the float collar is to provide a landing seat for the wiper plugs some distance above the float shoe so that good quality cement is inside and outside the casing around the shoe. In other words if one displaces a wiper plug all the way down to the shoe there would be some contaminated cement ahead of the wiper plug and it would be around the outside of the shoe. Bad cement around the shoe may demand costly remediation. Thus, one must place the float collar at least two joints above the shoe. The check valve in the float collar serves as a redundant back up of the check valve in the shoe
Answer: (2)The aim of float collar and float shoe are totally different. Float shoe has valve inside and it avoid reverse flow of cement during cementing operation or while waiting the solidification of cement slurry. And also to avoid any leakage between casing and formation at the bottom, there is a need to cement between float shoe and float collar as well. So when you insert plug on float collar you provide this.
Answer:(3) 1. For redundancy. Driller loves backup. Float shoe will interact directly with borehole, so the risk of passing valve or damage is higher. Float collar will act as backup when it happened, to ensure no backflow after cement job finished.
2. Float collar act as a seat for your cementing plugs. In some places, tubular is cemented without shoetrack. While in some places sometime they don’t use cementing plugs. So, i would say this function of float collar is additional point.