Downhole swivel

Abstract

A downhole tool includes a first sub, a second sub, and a clutch assembly positioned between the first sub and the second sub. The clutch assembly is configured to allow rotation between the first sub and the second sub in a first direction, and to prevent rotation between the first sub and the second sub in a second, opposite direction, when a compression force is applied to the downhole tool, when a tension force is applied to the downhole tool, and when no axial force is applied to the downhole tool.

What is claimed is: 
     
         1 . A downhole tool, comprising:
 a first sub;   a second sub; and   a clutch assembly positioned between the first sub and the second sub, wherein the clutch assembly is configured to allow rotation between the first sub and the second sub in a first direction, and to prevent rotation between the first sub and the second sub in a second, opposite direction, when a compression force is applied to the downhole tool, when a tension force is applied to the downhole tool, and when no axial force is applied to the downhole tool.   
     
     
         2 . The downhole tool of  claim 1 , further comprising:
 an outer housing that is coupled to the second sub such that the outer housing is restrained from rotation relative to the second sub; and   an inner mandrel disposed within the outer housing and coupled to the first sub such that the inner mandrel is restrained from rotation relative to the first sub,   wherein the clutch assembly comprises:
 a body coupled to the inner mandrel, wherein one or more tapered pockets are defined in the body; and 
 one or more clutch elements positioned in the one or more tapered pockets, wherein the one or more clutch elements are configured to produce a mechanical interference that resists rotation of the inner mandrel relative to the outer housing in the second direction. 
   
     
     
         3 . The downhole tool of  claim 2 , wherein the outer housing is integrally-formed with the second sub, and wherein the body of the clutch assembly is integrally-formed with the inner mandrel. 
     
     
         4 . The downhole tool of  claim 2 , wherein the one or more clutch elements comprise one or more cylindrical or spherical rollers. 
     
     
         5 . The downhole tool of  claim 2 , wherein the clutch assembly further comprises:
 a engaging member positioned partially in the body and extending into one of the one or more pockets, wherein the engaging member pushes against the one of the one or more clutch elements when the first sub rotates in the first direction relative to the second sub; and   a biasing member that forces the engaging member towards the one of the one or more pockets, to preload the clutch assembly.   
     
     
         6 . The downhole tool of  claim 2 , further comprising:
 a load ring coupled to the outer housing;   a first axial thrust bearing positioned between the first sub and a first axial side of the load ring; and   a second axial thrust bearing positioned axially between a shoulder of the inner mandrel and a second axial side of the load ring, and radially within the outer housing.   
     
     
         7 . The downhole tool of  claim 6 , further comprising a cover coupled to the first sub and extending over the first axial thrust bearing. 
     
     
         8 . The downhole tool of  claim 2 , wherein the inner mandrel is fixed to the first sub, and wherein the second sub is rotatable relative to the inner mandrel. 
     
     
         9 . A downhole tool, comprising:
 a first sub configured to connect to a first tubular;   a second sub configured to connect to a second tubular;   an outer housing coupled to the second sub and extending toward and separated axially apart from the first sub;   an inner mandrel positioned at least partially within the first and second subs, the inner mandrel being rotatable relative to the second sub and connected to and prevented from rotating relative to the first sub; and   a clutch assembly received within the outer housing and coupled with the inner mandrel, the clutch assembly comprising a body having a pocket formed therein, and a clutch element movably positioned in the pocket, wherein the clutch element permits the inner mandrel to rotate in a first direction relative to the outer housing and is engageable with the body and an inner diameter surface of the outer housing to prevent rotation of the inner mandrel relative to the outer housing in a second direction.   
     
     
         10 . The downhole tool of  claim 9 , wherein the pocket has a decreasing depth as proceeding in the first direction. 
     
     
         11 . The downhole tool of  claim 9 , wherein the clutch element comprises one or more cylindrical rollers. 
     
     
         12 . The downhole tool of  claim 9 , wherein the clutch assembly comprises one or more engaging members extending through a recess defined in a sidewall of the pocket, wherein the one or more engaging members engage the clutch element when the body of the clutch assembly rotates in the first direction relative to the outer housing. 
     
     
         13 . The downhole tool of  claim 12 , wherein the clutch assembly comprises a biasing member connected to the one or more engaging members, the biasing member being configured to bias the engaging member toward the clutch element, to preload the clutch assembly. 
     
     
         14 . The downhole tool of  claim 9 , further comprising:
 a load ring coupled to the outer housing; and   first and second axial thrust bearings, wherein the inner mandrel comprises a shoulder, the first axial thrust bearing being positioned between the shoulder and the load ring, and the second axial thrust bearing being positioned between the first sub and the load ring.   
     
     
         15 . The downhole tool of  claim 14 , wherein the body of the clutch is integral with the shoulder. 
     
     
         16 . The downhole tool of  claim 14 , further comprising a radial bearing positioned between the inner mandrel and the outer housing. 
     
     
         17 . The downhole tool of  claim 9 , wherein a plurality of pockets, including the pocket, are defined in the body of the clutch assembly, and wherein the clutch assembly includes a plurality of clutch elements, including the clutch element, that are positioned within respective ones of the plurality of pockets. 
     
     
         18 . The downhole tool of  claim 17 , wherein the pockets are positioned at approximately equal angular intervals around the body of the clutch. 
     
     
         19 . A method for isolating rotation in one direction and transmitting rotation in another direction in a tubular string, the method comprising:
 connecting a swivel to a tubular string, the swivel comprising:
 a first sub configured to connect to a first tubular; 
 a second sub configured to connect to a second tubular, wherein the second sub comprises an outer housing extending toward and separated axially apart from the first sub; 
 an inner mandrel positioned at least partially within the first and second subs, the inner mandrel being rotatable relative to the second sub and connected to and prevented from rotating relative to the first sub; and 
 a clutch assembly received within the outer housing and coupled with the inner mandrel, the clutch assembly comprising a body having a pocket formed therein, and a clutch element movably positioned in the pocket, wherein the clutch element permits the inner mandrel to rotate in a first circumferential direction relative to the outer housing and is engageable with the body and an inner diameter surface of the outer housing to prevent rotation of the inner mandrel relative to the outer housing in a second circumferential direction. 
   deploying the tubular string and the swivel into a well;   rotating the tubular string in the first circumferential direction, wherein the rotation in the first circumferential direction causes first sub to rotate relative to the second sub; and   rotating the tubular string in the second circumferential direction, wherein the rotation in the second circumferential direction causes the clutch assembly to engage the body and the outer housing, such that the first and second subs to rotate together.   
     
     
         20 . The method of  claim 19 , wherein the swivel comprises a plurality of pockets, including the pocket, are defined in the body of the clutch assembly, and wherein the clutch assembly includes a plurality of clutch elements, including the clutch element, that are positioned within respective ones of the plurality of pockets, and wherein, when rotating the tubular string in the second circumferential direction, the plurality of clutch elements engage the outer housing and prevent relative rotation therebetween.