Oil well mandrel and stabilizing sleeve assembly

Claim 1

A two-piece stabilizing tool assembly that may be inserted between upper and lower sections of a drill pipe string, said sections at their adjacent ends having threaded portions, said assembly including; a. an elongate rigid mandrel through which a longitudinal bore extends, said mandrel having upper and lower portions that define a circumferential body shoulder at their junction, said mandrel having upper and lower threads on said upper and lower portions that engage said threaded portions of said upper and lower drill pipe sections, said lower mandrel portion having longitudinally spaced upper and lower external cylindrical surfaces defined thereon that have threads formed on said mandrel extending therebetween, with a first circumferential groove formed in said first surface, and a circumferential recess in the external portion of said mandrell intermediate said upper and lower cylindrical surfaces; b. a generally cylindrical stabilizing sleeve having a plurality of spaced longitudinally extending blades on the exterior surface thereof and first and second longitudinally spaced cylindrical surfaces on the interior of said sleeve that have threads defined on said sleeve extending therebetween, with said sleeve, when rotated to place said threads thereon in full engagement with said threads on said mandrell, disposing said first and second cylindrical surfaces in transverse alignment with said upper and lower cylindrical surfaces on said mandrel, a transverse passage in said sleeve that has one end in communication with said recess and the other end situated in a space between said blades, and a second transverse circumferential groove in said second surface that extends outwardly therefrom; c. first and second resilient sealing rings, said first ring disposed in said first groove and in sealing contact with said first cylindrical surface, and said second ring disposed in said second groove and in sealing contact with said lower cylindrical surface; and d. first means mounted on said sleeve and in communication with said passage for allowing a flowable, substaNtially incompressible lubricant to be discharged under pressure into said recess and the spaces between the engaging threads of said mandrel and sleeve between said first and second sealing rings to provide a confined body of said lubricant that prevents drilling mud and abrasive particles flowing to positions between said mandrel and sleeve and which body at all times fully lubricates the engaging threads of said sleeve and mandrel to minimize wear thereon as said mandrel and sleeve are subjected to intermittent shocks during a drilling operation involving said drill string.