Using magnetic force/field for drill bits and other cutting tools

Abstract

A cutting element assembly includes a rotatable cutting element having an axis of rotation extending axially therethrough, a cutting face and a body extending axially downward from the cutting face, at least one retention mechanism disposed adjacent to the rotatable cutting element, and a first magnet disposed at a back face of the rotatable cutting element.

What is claimed is: 
     
         1 . A cutting element assembly, comprising:
 a rotatable cutting element comprising an axis of rotation extending axially therethrough, a cutting face and a body extending axially downward from the cutting face;   at least one retention mechanism disposed adjacent to the rotatable cutting element; and   a first magnet disposed at a back face of the rotatable cutting element.   
     
     
         2 . The cutting element assembly of  claim 1 , further comprising a sleeve, wherein the rotatable cutting element is partially disposed within the sleeve. 
     
     
         3 . The cutting element assembly of  claim 2 , further comprising a ferrofluid disposed between the rotatable cutting element and the sleeve. 
     
     
         4 . The cutting element assembly of  claim 1 , further comprising a second magnet disposed adjacent to the first magnet and opposite the back face. 
     
     
         5 . The cutting element assembly of  claim 4 , wherein the first magnet and the second magnet each have poles, and wherein the same poles of the first and second magnets are positioned facing each other. 
     
     
         6 . The cutting element assembly of  claim 1 , wherein the first magnet comprises an electromagnet. 
     
     
         7 . The cutting element assembly of  claim 1 , wherein the first magnet comprises a permanent magnet. 
     
     
         8 . The cutting element assembly of  claim 3 , wherein the ferrofluid comprises a plurality of ferromagnetic nanoparticles. 
     
     
         9 . A downhole cutting tool, comprising:
 a body;   a plurality of blades extending radially from the body;   a plurality of cutter pockets disposed on the plurality of blades;   at least one cutting element assembly disposed in the cutter pockets, wherein the at least one cutting element assembly comprises:
 a rotatable cutting element retained in the at least one cutter pocket, the rotatable cutting element comprising an axis of rotation extending axially therethrough, a cutting face and a body extending axially downward from the cutting face; and 
 a first magnet disposed at a back face of the rotatable cutting element. 
   
     
     
         10 . The downhole cutting tool of  claim 9 , wherein a bottom side of the cutter pocket comprises a ferromagnetic material. 
     
     
         11 . The downhole cutting tool of  claim 10 , wherein the cutting element assembly further comprises a sleeve and at least one retention mechanism disposed between the rotatable cutting element and the sleeve. 
     
     
         12 . The downhole cutting tool of  claim 11 , further comprising a ferrofluid disposed between the rotatable cutting element and the sleeve. 
     
     
         13 . The downhole cutting tool of  claim 9 , further comprising a second magnet disposed adjacent to the first magnet and opposite the back face. 
     
     
         14 . The downhole cutting tool of  claim 13 , wherein the first magnet and the second magnet each have poles, and wherein the same poles of the first and second magnets are positioned facing each other. 
     
     
         15 . The downhole cutting tool of  claim 9 , wherein the first magnet comprises an electromagnet. 
     
     
         16 . The downhole cutting tool of  claim 9 , wherein the first magnet comprises a permanent magnet. 
     
     
         17 . A downhole tool, comprising:
 at least one dynamic component;   at least one magnet disposed adjacent to the at least one dynamic component; and   a ferrofluid adjacent the at least one magnet and a portion of the at least one dynamic component.   
     
     
         18 . The downhole tool of  claim 17 , wherein the downhole cutting tool is a drill bit, comprising:
 a bit body;   a journal extending from the bit body, wherein the at least one rotatable structure is retained to the journal;   wherein the bearing system is disposed between the at least one rotatable structure and the journal;   wherein the at least one magnet is disposed between the at least one rotatable structure and the journal; and   wherein the ferrofluid is disposed between the at least one rotatable structure and the journal.   
     
     
         19 . The downhole tool of  claim 20 , wherein the bearing system comprises an o-ring seal and the at least one magnet comprises a ring magnet disposed proximate to the o-ring seal. 
     
     
         20 . The downhole tool of  claim 20 , wherein the ferrofluid is a ferrofluid grease comprising ferropowder and grease. 
     
     
         21 . The downhole tool of  claim 17 , wherein the tool comprises a reamer, an indexable bit, a percussion bit, a hole opener, a turbine, a drilling motor, a stabilizer, a measurement while drilling tool, a logging while drilling tool, a steering tool, turbine, an alternator, a production pump, an under-reamer, a hole-opener, a turbine-alternator, an adjustable whipstock, or a bent sub.