1.        The float shoe has the function of guiding-shoe. The automatic fill-up devices inside can allow the mud following back inside casing by alternation. This way can ensure the casing string in safety as well as fulfil the requirement of floating down the casing string, reduce some hook load to the rig lifting system. In the course of running casing, it can keep the mud flowing; In differential pressure condition, it makes the pressure inside casing smaller than that outside casing, improves the bonding quality for the first bond zone.

2.        The float collar can keep the casing string floating in the hole by not full filling with the mud. When casing run into the hole, the mud pressure outside the casing string shuts up the check valve to prevent the mud from entering casing. Float collar can be connected onto the first joint of casing string or the second joint or the third joint. In the majority condition, there is one or even more casing singles between the shoe and the collar. When the rubber plug is pumped down and landed in the rubber seat, the bumping pressure occurs, the cement slurry is completely displaced out, but float collar with rubber plug can ensure the interval between float collar with rubber plug can ensure the interval between float shoe and float collar is full filled with cement slurry to insure this section of casing string is commendably bonded.

Characteristic：

1.        Simple in structure, reasonable in design.

2.        Inner body is made of material that can be easily drilled out.

3.        The valves inside the float shoe and float collar can take the function of positive opening and invert direction closing just like check valves.

4.        Technical criterion in design and manufacturing API Spec 5CT-5B-JB1.