Restriction sub with deformable plastic sleeve
OwnerRobert E. Bodeinventor
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Abstract
In accordance with an illustrative embodiment of the present invention, a restriction sub apparatus for use during well cementing operations includes a tubular body having an internal annular recess, and a plastic restriction sleeve mounted in the recess, such sleeve having an inner diameter which is less than the inner diameter of the body so that when a drive plate on a cement displacement plug encounters the inner portion of the sleeve during downward movement, such inner portion is progressively deformed and bulged inward until the bulge dissipates into a recessed region near the bottom end of the sleeve. The resistance afforded by the plastic sleeve to downward movement of the plug provides a positive pressure surge indication at the surface that the plug is located at a particular depth in the casing.
Claims7
A restriction sub apparatus for use in a well casing to provide a surface indication of the downhole position of a cement displacement plug, comprising;
- a tubular body having means at its ends for connecting said body in the casing, said body having an internal bore and an internal annular recess formed therein;
- and a plastic sleeve member mounted in said recess, said sleeve member having a mid-portion with an inner diameter that is less than the inner diameter of said bore, and a lower portion that provides annular recess means to provide space for extrusion of an inner portion of said sleeve member as a drive plate passes downward therepast.
Dependencies are inferred from the claim text.