Hydraulically-Actuated Propellant Stimulation Downhole Tool

Abstract

A hydraulically-actuated propellant stimulation downhole tool for hydrocarbon wells. According to one embodiment of the invention, the tool comprises a first section having an internal sidewall defining at least a portion of a flowpath, and a ported outer sidewall and a propellant volume having at least a portion within said first section. An annular portion has at least one chamber having an end positioned adjacent to the propellant volume and an inlet providing a communication path to said flowpath. A detonator assembly is located within each chamber proximal to the propellant volume such that detonation of the assembly causes detonation of the propellant volume. A firing pin is propelled toward the detonation assembly by providing communication between the chamber and the flow path, causing a pressure differential between the pressure isolated ends of the firing pin.

We claim: 
     
         1 . A downhole tool for stimulating a hydrocarbon-producing formation, the downhole tool comprising:
 a first section having an internal sidewall defining at least a portion of a flowpath, and an outer sidewall;   a propellant volume having at least a portion within said first section;   an annular portion with at least one chamber having an end positioned adjacent to said propellant volume and an inlet;   at least one detonator assembly within said at least one chamber proximal to said end;   at least one firing pin within said at least one chamber, said at least one firing pin having a first end pressure isolated from a second end;   a second section at least partially separating said flowpath and the exterior of the downhole tool; and   a sleeve assembly defining at least a portion of said flowpath and moveable between a first position and a second position.   
     
     
         2 . The downhole tool of  claim 1  wherein in said first position said sleeve assembly is between the inlet of said at least one chamber and said flowpath. 
     
     
         3 . The downhole tool of  claim 1  wherein at least a portion of said propellant volume is between said internal sidewall and said outer sidewall. 
     
     
         4 . The downhole tool of  claim 1  wherein said second section has at least one flow port defining a fluid communication path between said flowpath and the exterior of the downhole tool, and wherein in said first position said sleeve assembly is between said at least one flow port and said flowpath. 
     
     
         5 . The downhole tool of  claim 4  wherein said at least one detonator assembly comprises a isolation bulkhead proximal to said propellant volume, a shaped charge adjacent said isolation bulkhead, a primer case adjacent said shaped charge, and a primer adjacent said primer case. 
     
     
         6 . The downhole tool of  claim 4  wherein said sleeve assembly comprises:
 a piston sleeve having a sidewall and at least one port providing a communication path through said sidewall; 
 an insert sleeve engagable with said piston sleeve and having spaced-apart upper and lower sealing rings located upwell and downwell, respectively, of said at least one flow port when said sleeve assembly is in said first position; and 
 an insert sleeve locking key coupling said insert sleeve to said piston sleeve when in said first position. 
 
     
     
         7 . The downhole tool of  claim 6  wherein said insert sleeve further comprises a ball seat having an orifice defining a portion of said flowpath and engagable by a ball to substantially prevent fluid communication through said flowpath to below said insert sleeve. 
     
     
         8 . The downhole tool of  claim 6  wherein in said first position said insert sleeve is attached to said second section with a plurality of circumferentially aligned shear pins. 
     
     
         9 . The downhole tool of  claim 6  further comprising a firing pin locking key circumferentially disposed around said sleeve assembly, wherein in said first position said firing pin locking key is engaged with a retention groove circumferentially formed around said at least one firing pin, and wherein in said second position said firing pin locking key is disengaged from said retention groove. 
     
     
         10 . The downhole tool of  claim 9  wherein said sleeve assembly defines an outer groove circumferentially disposed therearound, and wherein in said second position:
 said at least one port is substantially radially aligned with said inlet of said at least one chamber; 
 said firing pin locking key is positioned in said outer groove and disengaged from said at least one firing pin; and 
 said piston sleeve is decoupled from said insert sleeve. 
 
     
     
         11 . The downhole tool of  claim 9  wherein:
 said second section further comprises an inner shoulder adjacent a flanged section, said inner shoulder having a radius; 
 a piston locking key is positioned in said flanged section and disengaged from said insert sleeve when in said sleeve assembly is in said second position; and 
 said radius of said shoulder is smaller than the radius of a bottom end of said piston sleeve to block movement of said sleeve below said shoulder.