Restriction subs for setting cement plugs in wells
OwnerRobert E. Bodeinventor
Life of this patent
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Abstract
In accordance with illustrative embodiments of the present invention, restriction subs for use in setting cement plugs in wells include a tubular threaded adapter having an internal annular recess, and a metal restriction sleeve mount in such recess. In one embodiment, the sleeve has a corrugation that extends into the bore of the adapter to provide a deformable restriction; in another embodiment the sleeve has curved resilient tabs whose free ends extend into such bore. The restrictions are cooperable with a displacement plug having a metal expander member on its nose so that a distinct pressure is required to cause the expander member and plug to be forced through the restriction.
Claims14
A restriction sub for use in providing a surface indication of the downhole position of a plug member in a pipe string, comprising:
- a tubular body having means at its ends for connecting the body in a pipe string, said body having a bore and an internal annular recess, said bore having a first inner diameter and said recess having a second inner diameter, said second inner diameter being larger than said first inner diameter;
- a circular sleeve mounted in said recess, said sleeve having an inner peripheral surface defined between upper and lower end surfaces, said inner peripheral surface of said sleeve defining an inwardly extending restriction section for providing a yieldable obstruction to the passage of said plug member downward through said bore of said body, said restriction section forming a unitary portion of said sleeve and being located entirely between said upper and lower end surfaces.
Apparatus for launching plugs into a pipe string during a well cementing operation, comprising an elongated tubular body having a cap releasably secured to its upper end, said body defining an axial bore having a first inner diameter and recess means having a second inner diameter that is larger than said first inner diameter;
- and spaced upper and lower restriction means mounted in said recess means, each of said restriction means including an annular element formed with yieldable means extending into said bore of said body, said yieldable means being cooperable with a fluid-driven plug to enable passage of said plug therethrough in response to a predetermined fluid pressure.
Dependencies are inferred from the claim text.