The float casing collar is a casing collar equipped with a check valve. It is one of the casing accessories. It can be used in combination with casing floating shoes in deep wells and special wells to improve the safety of cementing operations. In the process of running the casing, the unidirectional flow of the annular drilling fluid is realized, the backflow of the cement slurry is prevented during the cementing process, and the pressure release and setting after cementing are realized, which helps to improve the cementation quality of the cement sheath and the casing; at the same time, By pouring drilling fluid into the casing string to adjust its buoyancy, the suspension weight of the casing can meet the design requirements of the casing running operation.

The structure is divided into two types: nylon ball floating hoop and spherical steel valve floating hoop. The former is used for shallow wells and the latter is used for deep wells. When using a float casing collar, the speed of lowering the casing string should be controlled to prevent pressure excitation caused by too fast lowering, resulting in seal failure or crushing of fragile formations. By pouring drilling fluid into the casing and adjusting the pressure difference of the hydrostatic column inside and outside the casing, the casing can be effectively prevented from being collapsed.