Patent ID: 7090004
Filing Date: 2006-08-15
Classification: E21B

Abstract:
1. A cement float for use in a wellbore tubing string comprising: a mandrel including a first end, a second end, a bore extending from the first end to the second end including a fluid flow control device therein and outer side surfaces defining a tapering outer diameter from the first end of the mandrel to the second end; an outer lock sleeve including an outer surface and a sleeve bore through the sleeve, the outer lock sleeve retained at least about the outer side surfaces of the mandrel with the mandrel extending through the sleeve bore, the sleeve bore having a taper to complement and be coactable with the tapering outer diameter of the mandrel outer side surfaces and the sleeve bore and the mandrel outer side surfaces defining interfacing surfaces therebetween, the sleeve being expandable radially outwardly by driving the mandrel against the taper of the sleeve bore to place the cement float in an anchored position in the tubing string with the outer lock sleeve wedged between the mandrel and the tubing string, the outer lock sleeve and the mandrel being formed over at least a portion of their interfacing surfaces to be frictionally and/or mechanically interactive to provide self locking against sliding movement therebetween that would dislodge the cement float from its anchored position.