Retractable Underreamer

Abstract

An underreamer is provided in which the cutting elements are retracted into the tool body during run in, extensible for the performance of cutting operations, and retractable into the body of the tool afterwards.

1 . An underreamer for use in well bores, comprising
 a tool body,   a selectively positional cam within said tool body, and   a cutting element positional by said cam in a retracted position relative to said tool body, and also positional by said cam in an extended position relative to said tool body, wherein the motion of said cutting element relative to said tool body is essentially perpendicular to the longitudinal axis of said tool body.   
     
     
         2 . The underreamer of  claim 1 , wherein said cam is selectively positional to retain said cutting element in a retracted position during run in. 
     
     
         3 . The underreamer of  claim 1 , wherein said cam is selectively positional to retain said cutting element in an extended position during cutting operations. 
     
     
         4 . The underreamer of  claim 1 , wherein said cam is selectively positional to retain said cutting element in a retracted position after cutting operations are completed. 
     
     
         5 . The underreamer of  claim 1 , additionally comprising a seat capable of engaging a plugging device, wherein said seat obstructs fluid flow through the underreamer when a plugging device is engaged on said seat. 
     
     
         6 . The underreamer of  claim 5 , additionally comprising a flow diverter, wherein said flow diverter allows fluid flow around said seat when said cam positions said cutting element in an extended position. 
     
     
         7 . The underreamer of  claim 5 , additionally comprising a second seat capable of engaging a second plugging device, wherein said second seat obstructs fluid flow through the underreamer when a second plugging device is engaged on said second seat. 
     
     
         8 . The underreamer of  claim 7 , additionally comprising a second flow diverter, wherein said second flow diverter allows fluid flow around said second seat when said cam positions said cutting element in a retracted position. 
     
     
         9 . The underreamer of  claim 1 , additionally comprising a plurality of cutting elements positional by said cam in a retracted position, and also positional by said cam in an extended position. 
     
     
         10 . The underreamer of  claim 1 , additionally comprising a stabilizer element, wherein said stabilizer element may be extended and retracted in the same manner as said cutting element. 
     
     
         11 . The underreamer of  claim 10 , comprising a plurality of stabilizer elements. 
     
     
         12 . The underreamer of  claim 1 , wherein said tool body additionally comprises a housing cover, and wherein said housing cover is selectively detachable from the remainder of said tool body. 
     
     
         13 . The underreamer of  claim 12 , additionally comprising a key, wherein said key extends into said tool body and provides a positive positional lock between said tool body and said housing cover. 
     
     
         14 . The underreamer of  claim 12 , additionally comprising a key, wherein said key extends into said housing cover and provides a positive positional lock between said tool body and said housing cover. 
     
     
         15 . A method of performing an underreaming operation in a well bore, comprising the steps of
 running a tool body into position downhole with a cutting element retracted relative to said tool body,   selectively positioning a cam within said tool body to extend said cutting element relative to said tool body by moving said cutting element in a direction essentially perpendicular to the longitudinal axis of said tool body,   underreaming the wellbore, and   selectively positioning said cam to retract said cutting element.   
     
     
         16 . The method of  claim 15 , additionally comprising the step of providing a pressure indication when the step of selectively positioning a cam within said tool body to extend said cutting element relative to said tool body is complete. 
     
     
         17 . The method of  claim 15 , additionally comprising the step of providing a pressure indication when the step of selectively positioning said cam to retract said cutting element is complete.