Float collar

A system for regulating drilling fluid and cement flow through a tubular member being run in and cemented to a wellbore, said system comprising:

• a metal housing being fixed within the tubular member and positioned near the lower end of the tubular member, said housing having an axial bore therethrough such as to provide a conduit for drilling fluid and cement to pass from within the tubular member downward into the wellbore,
• at least one plastic flapper valve arranged within the housing having an open position where drilling fluid may flow through the housing, and a closed position where the valve permits cement to flow downward from the tubular member into the wellbore, but not upward from the wellbore into the casing liner,
• a plastic sleeve arranged within the housing and having a drop ball seat with an axial bore therethrough integrally formed therein, said sleeve being movable from a fixed position where shear pins positioned near the top of the sleeve prevent the sleeve from sliding thereby holding the valves in the open position, to a displaced position where the sleeve is displaced axially downward out of the housing to permit the valves to move to the closed position, and
• a drop ball having a diameter greater than the diameter of the axial bore through the drop ball seat of the plastic sleeve but less than or equal to the inner diameter of the sleeve, said drop ball being released into the housing and sealing with the drop ball seat such that said displacement of the sleeve occurs when drilling fluid pressure is increased above the drop ball to a predetermined level to shear the shear pins,
• wherein said plastic materials of said flapper valve and said sleeve comprise plastics which can withstand operational conditions within a wellbore for the duration of run in and cementing operations.

A float collar for regulating drilling fluid and cement flow, comprising:

• a tubular body having an interior;
• a sleeve, positionable within said interior of said tubular body and releasably connectable to said tubular body;
• and
• a normally closed valve, comprising a plastic material which can withstand operational conditions within a wellbore for the duration of run in and cementing operations, wherein said valve is held open by said sleeve when said sleeve is positioned within and connected to said tubular body.

A float collar for regulating drilling fluid and cement flow, comprising:

• a tubular body having an interior;
• a sleeve, comprising a plastic material which can withstand operational conditions within a wellbore for the duration of run in and cementing operations, positionable within said interior of said tubular body and releasably connectable to said tubular body;
• and
• a normally closed valve, wherein said valve is held open by said sleeve when said sleeve is positioned within and connected to said tubular body.