Cam mechanism for downhole rotary valve actuation and a method for drilling

Abstract

A method of drilling a wellbore with a downhole tool having a cam piston, and a rotary piston includes providing a first flow of fluid to the downhole tool. The first flow of fluid causes the cam piston to move axially downward, thereby rotating a rotary valve of the rotary piston, which in turn places the downhole tool in a compressed position to activate a secondary tool. Next the formation may be drilled with the downhole tool in a compressed position. A second flow of fluid may be provided to the downhole tool to move the cam piston axially downward thereby rotating the rotary valve and deactivating the secondary tool.

1 .- 14 . (canceled) 
     
     
         15 . A method of drilling, the method comprising:
 disposing a downhole tool in a wellbore in an uncompressed position, the downhole tool comprising a cam piston and a rotary piston, the rotary piston having a rotary valve;   providing a first flow of fluid to the downhole tool, the first flow of fluid moving the cam piston axially downward, thereby rotating the rotary valve to place the downhole tool in a compressed position and to activate a secondary tool;   drilling formation with the downhole tool in a compressed position; and   providing a second flow of fluid to the downhole tool, the second flow of fluid rotating the cam piston while the rotary piston is stationary.   
     
     
         16 . (canceled) 
     
     
         17 . The method of  claim 21 , wherein when the downhole tool is in a compressed position, one or more blocks of the secondary tool are radially expanded. 
     
     
         18 . The method of  claim 15 , wherein a flow rate of at least one of the first flow and the second flow is within a trigger range flow rate. 
     
     
         19 . The method of  claim 15 , wherein the downhole tool further comprises a earn track and an auxiliary track, wherein a guide pin is disposed in the cam track and a position pin is disposed in the auxiliary track. 
     
     
         20 . The method of  claim 19 , further comprising moving the guide pin in the cam track and moving the position pin in a non-corresponding track pattern of the auxiliary track when the flow of fluid is in a trigger range. 
     
     
         21 . The method of  claim 15 , wherein the secondary tool is one selected from a group consisting of a reamer and a stabilizer. 
     
     
         22 . The method of  claim 18 , further comprising providing a third flow of fluid above the trigger range, thereby rotating the cam piston while the rotary valve stays stationary. 
     
     
         23 . A downhole tool comprising:
 a cam housing having a guide pin;   a cam piston having a cam track disposed at least partially within the cam housing, the guide pin of the cam housing engaged with the cam track;   a rotary piston disposed at least partially within the cam piston, the rotary piston having a rotary valve and an auxiliary track; and   a position pin extending through a cam flange of the cam piston and engaged with the auxiliary track of the rotary piston,   wherein the rotary piston is configured to rotate with the cam piston with a first flow of fluid and remain stationary as the cam piston rotates with a second flow of fluid.   
     
     
         24 . The downhole tool of  claim 23 , wherein the cam track includes one or more cycles, each cycle having a start position and an end position, wherein an end position of a first cycle is a start position an adjacent cycle, and wherein each cycle includes at least two return paths. 
     
     
         25 . The downhole tool of  claim 24 , wherein the auxiliary track includes one or more cycles, wherein a track pattern of each cycle of the one or more cycles of the auxiliary track corresponds to at least one return path of the cam track. 
     
     
         26 . The downhole tool of  claim 23 , further comprising pressure signal slots disposed in at least one of the rotary piston or the cam piston, wherein fluid flows through the pressure signal slots when the downhole tool is in a compressed position. 
     
     
         27 . The downhole tool of  claim 23 , further comprising a spring disposed around at least a portion of the cam piston. 
     
     
         28 . The downhole tool of  claim 23 , wherein the spring is biased to move the cam piston axially up hole. 
     
     
         29 . The downhole tool of  claim 23 , wherein at least a portion of the cam piston is located in a secondary tool.