Hydraulic actuation of a downhole tool assembly

Abstract

A downhole tool assembly is configured for repeated and selective hydraulic actuation and deactuation. A piston assembly is configured to reciprocate axially in a downhole tool body. The piston assembly reciprocates between a first axial position and second and third axial positions that axially oppose the first position. The downhole tool is actuated when the piston assembly is in the third axial position and deactuated when the piston assembly is in either of the first or second axial positions. A spring member biases the piston assembly towards the first axial position while drilling fluid pressure in the tool body urges the piston assembly towards the second and third axial positions. Downhole tool actuation and deactuation may be controlled from the surface, for example, via cycling the drilling fluid flow rate.

What is claimed is: 
     
         1 . A downhole tool, comprising:
 a tool body having a through bore;   a mandrel in the tool body, the mandrel including at least one port; and   a piston assembly having the through bore extending therethrough, the piston assembly including at least one piston configured to reciprocate axially between a first, second, and third axial positions, and fluid flow being permitted through the through bore when the piston assembly is in each of the first, second, and third axial positions.   
     
     
         2 . The downhole tool of  claim 1 , further comprising:
 a bias member in the tool body and configured to bias the piston assembly toward the first axial position.   
     
     
         3 . The downhole tool of  claim 2 , the piston assembly being configured to move against the bias of the bias member in response to fluid flow in the through bore. 
     
     
         4 . The downhole tool of  claim 1 , the piston assembly being at least partially positioned in the mandrel. 
     
     
         5 . The downhole tool of  claim 1 , further comprising:
 a plurality of expandable cutting structures configured to be in a radially extended position when the piston assembly is in the third axial position, and to be in a radially retracted position when the piston assembly is in at least one of the first axial position or the second axial position.   
     
     
         6 . The downhole tool of  claim 1 , the at least one piston including first and second cam profiles, the first cam profile being oriented in an uphole direction and the second cam profile being oriented in a downhole direction, and the tool body including at least one guide pin, the at least one guide pin being configured to engage the first cam profile when the piston assembly is in the first axial position, and to engage the second cam profile when the piston assembly is in at least one of the second or third axial positions. 
     
     
         7 . The downhole tool of  claim 6 , the at least one guide pin including at least a first guide pin configured to engage the first cam profile when the piston assembly is in the first axial position, and a second guide pin configured to engage the second cam profile when the piston assembly is in at least one of the second or third axial positions. 
     
     
         8 . The downhole tool of  claim 7 , the second cam profile including alternating deep and shallow troughs, and the second guide pin being configured to engage a corresponding one of the shallow troughs when the piston assembly is in the second axial position and a corresponding one of the deep troughs when the piston assembly is in the third axial position. 
     
     
         9 . The downhole tool of  claim 1 , the piston assembly being configured to transition from the second axial position to the first axial position and then to the third axial position when a fluid flow rate is cycled from a high flow rate to a low flow rate and back toward the high flow rate. 
     
     
         10 . The downhole tool of  claim 1 , the at least one piston including a cam piston having at least one groove in a radially outward facing surface of the cam piston, and the tool body including at least a first guide pin engaging the at least one groove. 
     
     
         11 . The downhole tool of  claim 10 , the cam piston including alternating cam slots and cam shoulders formed on an axial end of the cam piston, and the tool body including at least a first stop configured to engage at least one of the cam shoulders when the piston assembly is in the second axial position and at least one of the cam slots when the piston assembly is in the third axial position. 
     
     
         12 . The downhole tool of  claim 1 , the piston assembly being configured to transition from the second axial position to the first axial position and then to the third axial position when a fluid flow rate is cycled from a high flow rate, to a low flow rate, to an indexing flow rate, back to the low flow rate, and then toward the high flow rate. 
     
     
         13 . The downhole tool of  claim 1 , the at least one piston including a valve piston having at least one port configured to provide fluid communication between the through bore and an annular region between the tool body and a portion of the piston assembly when the piston assembly is in the third axial position, the valve piston port being sealingly engaged with the mandrel when the piston assembly is in at least one of the first or second axial positions. 
     
     
         14 . The downhole tool of  claim 13 , the port of the valve piston providing an alternative flow path around a nozzle when the piston assembly is in the third axial position, the alternative flow path being configured to route fluid from the through bore, through the annular region, and back into the through bore. 
     
     
         15 . The downhole tool of  claim 13 , the at least one piston including a cam piston having a plurality of apertures providing fluid communication between the annular region and the through bore. 
     
     
         16 . A tool, comprising:
 a tool body having a through bore;   a cam piston in the tool body, the cam piston including first and second cam profiles thereon, the cam piston configured to reciprocate axially in the tool body between a first axial position in which at least one guide pin engages the first cam profile and second and third axial positions in which the at least one guide pin engages the second cam profile, a radial fluid flow path being in fluid communication with the through bore when the cam piston is in the third axial position and out of fluid communication with the through bore when the cam piston is in at least one of the first or second axial positions, while fluid flow is permitted axially through the throughbore when the piston assembly is in each of the first, second, and third axial positions; and   a bias member in the tool body and configured to bias the cam piston toward the first axial position.   
     
     
         17 . The tool of  claim 16 , the at least one guide pin including a first guide pin configured to engage the first cam profile when the cam piston is in the first axial position, and a second guide pin configured to engage the second cam profile when the cam piston is in the second and third axial positions. 
     
     
         18 . The tool of  claim 17 , the second cam profile including circumferentially spaced, alternating deep and shallow troughs, and the second guide pin being configured to engage a corresponding one of the shallow troughs when the cam piston is in the second axial position and a corresponding one of the deep troughs when the cam piston is in the third axial position. 
     
     
         19 . The tool of  claim 16 , further comprising:
 a plurality of expandable cutting structures configured to extend radially outward from the tool body when the fluid flow path is in fluid communication with the through bore.   
     
     
         20 . A method for reaming a wellbore, comprising:
 using a drill string to position a reamer within a wellbore, the reamer including:
 a reamer body coupled to the drill string, the reamer body having a through bore; 
 a mandrel in the tool body, the mandrel including at least one port; 
 a piston assembly in the tool body, the piston assembly including at least one piston configured to reciprocate axially between first, second, and third axial positions using a cam and at least one guide pin; and 
 a plurality of expandable cutting structures in a retracted state and configured to selectively expand in response to movement of the piston assembly; and 
   adjusting a drilling fluid flow rate within the reamer, which adjusting of the drilling fluid flow rate causes the piston assembly to move using the cam and at least one guide pin in a cycle that includes:
 from the first axial position to the second axial position; 
 from the second axial position back to the first axial position; 
 from the first axial position to the third axial position; and 
 from the third axial position back to the first axial position.