Float Shoe

A float shoe is used in the drilling of oil and gas wells. It is a single cylindrical piece that performs the functions of both a float collar and a guide shoe. Its main purpose is to guide drilling equipment to the bottom of the well without snagging, like a guide shoe. It also contains a check valve to allow fluids to pass in only one direction, like a float collar. The float shoe is screwed onto the bottom of the casing string to guide the casing to the bottom of the well. It prevents mud from entering the casing. It also helps the casing to float during the descent, which decreases the load acting on the oil derrick and other topside drilling equipment

The float shoe body is made of alloy structural steel material, and the upper end is connected with the casing, and the lower end is a hemispherical cement head to guide the lowering of the casing. A back pressure valve is installed inside, and the space between the back pressure valve and the body is filled with oil well cement. The back pressure valve can be drilled with a PDC bit. The upper and lower passages of the valve are open when ex-work. When the casing is initially placed, the liquid in the well has no resistance to the float shoes. The pressure of the circulating mud presses the valve head downward for a displacement, and the three cleats at the end of the valve stem automatically fall off. After the pump is stopped, the valve presses tightly the valve seat upward under the action of the spring to act as a one-way valve. At this time, the drilling fluid or cement slurry can be pumped from upwards to downwards, but the fluid in the casing under the valve or in the annular space outside the casing cannot return to the rubber plug. The plug plays a role in separating the drilling fluid and the cement slurry and colliding with it during cementing operations. The plug has upper part and lower part, with the feature that the PDC bit could drill through.