Downhole Cutting Tool Having A Jetted Top Bushing

Abstract

A downhole cutting tool having a jetted top bushing. The cutting tool has a plurality of blades which rotate from a first, retracted position to a second, extended position. In this extended position, cutting surfaces on the blades contact the tubular wall, and rotation of the cutting tool enables cutting through the tubular. The blades are rotated by an internal piston which pushes down on portions of the blades in response to fluid flow through the tool. A plurality of fluid outlets or jets are positioned above (uphole from) the blades, whereby a portion of the fluid being pumped downhole flows out of the jets, into the annulus and onto the blades, keeping them clean and enhancing lifting of cuttings to the surface. The fluid outlet flow area may be easily changed, without disassembly of the cutting tool, by changing jets to different flow areas, or blanked off if desired.

I claim: 
     
         1 . A downhole tubular cutting tool, comprising:
 a main body having a longitudinal bore therethrough;   a plurality of blades rotatably attached to said main body and rotatable between a first position wherein said blades are substantially aligned with said main body, and a second position wherein said blades are rotated outwardly from said main body, said blades having cutting surfaces thereon;   a means for rotating said blades from said first position to said second position; and   a plurality of fluid outlets positioned uphole from said blades, said fluid outlets permitting fluid flow from said bore into an annulus between said cutting tool and a borehole.   
     
     
         2 . The cutting tool of  claim 1 , wherein said fluid outlets comprise removable jets disposed therein, at least one of said jets comprising a hole to yield a desired flow area therethrough, said jets being removable and replaceable from an exterior of said cutting tool. 
     
     
         3 . The cutting tool of  claim 2 , wherein fluid flow through at least one of said jets is angled downwardly toward said blades. 
     
     
         4 . The cutting tool of  claim 2 , wherein said jets are threadably engaged within said fluid outlets. 
     
     
         5 . The cutting tool of  claim 2 , wherein said jets are fixed in said fluid outlets by pins. 
     
     
         6 . The cutting tool of  claim 1 , wherein said means for rotating said blades comprises a piston slidably disposed in said bore of said main body, said piston comprising a bore therethrough, said piston moveable in a downhole direction under the influence of fluid pumped through said bore of said main body and said bore of said piston, said piston thereby bearing against a heel portion of said blades and rotating said blades to said second position. 
     
     
         7 . The cutting tool of  claim 1 , wherein said main body comprises a removable top bushing, and wherein said fluid outlets are disposed in said top bushing. 
     
     
         8 . The cutting tool of  claim 2 , wherein said main body comprises a removable top bushing, and wherein said fluid outlets are disposed in said top bushing. 
     
     
         9 . A downhole tubular cutting tool, comprising:
 a main body having a longitudinal bore therethrough;   a plurality of blades rotatably attached to said main body and rotatable between a first position wherein said blades are substantially aligned with said main body, and a second position wherein said blades are rotated outwardly from said main body, said blades having cutting surfaces thereon;   a piston slidably disposed in said bore of said main body, said piston comprising a bore therethrough, said piston moveable in a downhole direction under the influence of fluid pumped through said bore of said main body and said bore of said piston, said piston thereby bearing against a heel portion of said blades and rotating said blades to said second position; and   a plurality of fluid outlets positioned uphole from said blades, said fluid outlets permitting fluid flow from said bore into an annulus between said cutting tool and a borehole, said fluid outlets comprising removable jets disposed therein, at least one of said jets comprising a hole to yield a desired flow area therethrough, said jets being removable and replaceable from an exterior of said cutting tool.   
     
     
         10 . The cutting tool of  claim 9 , wherein fluid flow through at least one of said jets is angled downwardly toward said blades. 
     
     
         11 . The cutting tool of  claim 9 , wherein said jets are threadably engaged within said fluid outlets. 
     
     
         12 . The cutting tool of  claim 9 , wherein said jets are fixed in said fluid outlets by pins. 
     
     
         13 . The cutting tool of  claim 9 , wherein said main body comprises a removable top bushing, and wherein said fluid outlets are disposed in said top bushing. 
     
     
         14 . The cutting tool of  claim 13 , wherein fluid flow through at least one of said jets is angled downwardly toward said blades. 
     
     
         15 . The cutting tool of  claim 14 , wherein said jets are threadably engaged within said fluid outlets. 
     
     
         16 . The cutting tool of  claim 14 , wherein said jets are fixed in said fluid outlets by pins.