The float casing collar is mainly used to guide the casing string into the well, adjust the buoyancy of the casing string when running the casing, and accurately control the height of the cement plug in the casing during cementing, so as to ensure the cementing quality.

The float casing collar is basically the same as the floating shoe, except that the lower end is a male buckle, which is connected to the casing. There is an anti-rotation plum blossom hole on the upper end of the filling cement, which is coupled with the front end of the rubber stopper to prevent the rubber stopper from rotating when the rubber stopper is drilled with a PDC drill.

The body of the float casing collar is made of alloy structural steel, the upper end is connected to the casing, and the lower end is a hemispherical cement head to guide the casing down. It is equipped with a back pressure valve inside, and oil well cement is used to fill the space between the back pressure valve and the body. The back pressure valve can be drilled with a PDC drill. The upper and lower passages of the valve are open at the factory. When the casing is first laid, the liquid in the well has no resistance to the floating shoe. The pressure of the circulating mud pushes the valve head down by a displacement, and the three flaps at the end of the valve stem automatically fall off. After the pump is stopped, the valve presses the valve seat upward under the action of the spring, which acts as a one-way valve.