Wellbore drill bit with stationary and expandable blades

Abstract

A wellbore drill bit with stationary and expandable blades includes a drill bit body defining an internal volume. The stationary blades are attached and stationary with respect to the drill bit body. The stationary blades are spaced apart on an outer surface of the drill bit body to define openings; each defined between two consecutive stationary blades. The expandable blades are positioned in the respective spaces. Each expandable blade can transition between a retracted state and an open state. In the retracted state, each expandable blade is radially nearer to the longitudinal axis compared to each stationary blade. In the open state, each expandable blade extends radially away from the longitudinal axis to be radially farther away from the longitudinal axis compared to each stationary blade. The drill bit includes a ball activation mechanism that can be activated to transition the expandable blades between the retracted and open states.

1 . A wellbore drilling assembly comprising: 
 a wellbore drill bit comprising: 
 a drill bit body having a longitudinal axis, 
 a plurality of stationary blades attached to the drill bit body and stationary with respect to the drill bit body, the plurality of stationary blades configured to drill through a subterranean formation to form a wellbore, the plurality of stationary blades spaced apart on an outer surface of the drill bit body to define a plurality of openings, each opening defined between two consecutively spaced apart stationary blades, 
 a plurality of expandable blades positioned in the respective plurality of openings, each expandable blade configured to drill through the subterranean formation to form the wellbore, each expandable blade configured to transition between a retracted state, in which each expandable blade is radially nearer to the longitudinal axis compared to each stationary blade, and an open state, in which each expandable blade extends radially away from the longitudinal axis to be radially farther away from the longitudinal axis compared to each stationary blade, and 
 a ball activation mechanism comprising a plurality of ball seats axially offset from each other along the longitudinal axis, a first ball seat of the plurality of ball seats configured to receive a first ball to transition the plurality of expandable blades from the retracted state to the open state, a second ball seat of the plurality of ball seats configured to receive a second ball to transition the plurality of expandable blades from the open state to the retracted state; and 
   a plurality of balls comprising the first ball and the second ball.   
     
     
         2 . The assembly of  claim 1 , wherein the drill bit body defines an internal volume including the plurality of openings defined on the outer surface of the drill bit body, wherein, in the retracted state, the plurality of expandable blades reside within the internal volume of the drill bit body, wherein the first ball seat and the second ball seat are installed within the internal volume of the drill bit body. 
     
     
         3 . The assembly of  claim 2 , wherein the ball activation mechanism comprises a first piston positioned within the internal volume of the drill bit body, the first piston defining the first ball seat, the first piston configured to move axially within the internal volume of the drill bit body in response to axial pressure. 
     
     
         4 . The assembly of  claim 3 , wherein the first piston defines an internal volume, wherein the first piston comprises axial walls defining through openings, wherein, in an absence of the first ball in the first ball seat, the first piston is configured to permit wellbore fluid to flow along the longitudinal axis past the first piston, and in a presence of the first ball in the first ball seat, the first piston is configured to divert the wellbore fluid to flow through the internal volume of the first piston and through openings in the axial walls instead of past the first piston. 
     
     
         5 . The assembly of  claim 4 , wherein the ball activation mechanism comprises a second piston positioned within the internal volume of the drill bit body, the second piston defining the second ball seat, the second piston contacting the first piston, the second piston configured to move axially within the internal volume in response to axial pressure and to responsively axially move the first piston. 
     
     
         6 . The assembly of  claim 5 , wherein the ball activation mechanism comprises a plurality of pads positioned within the internal volume defined by the drill bit body, the plurality of pads connected to the plurality of expandable blades, the second piston contacting the plurality of pads, the plurality of pads and the plurality of expandable blades arranged such that an axial movement of the plurality of pads within the internal volume defined by the drill bit body causes a radial movement of the plurality of expandable blades between the retracted state and the open state. 
     
     
         7 . The assembly of  claim 6 , wherein, in an absence of the second ball in the second ball seat, the second piston is configured to permit wellbore fluid to flow along the longitudinal axis past the second piston, and in a presence of the second ball in the second ball seat, the second piston is configured to prevent the wellbore fluid to flow past the second piston, wherein the second piston is configured to move the plurality of pads along the longitudinal axis in response to the wellbore fluid being prevented from flowing past the second piston. 
     
     
         8 . The assembly of  claim 1 , wherein the first ball seat is smaller than the second ball seat. 
     
     
         9 . The assembly of  claim 8 , wherein the first ball is smaller than the second ball.  
     
     
         10 . The assembly of  claim 2 , wherein the plurality of stationary blades is attached to a first axial end of the drill bit body, wherein the drill bit body comprises a second axial end configured to receive the plurality of balls. 
     
     
         11 . The assembly of  claim 1 , further comprising a wellbore conveyance fluidically coupled to the second axial end, the wellbore conveyance configured to flow wellbore fluid through the second axial end, wherein the plurality of balls are flowed into the internal volume of the drill bit body with the wellbore fluid through the wellbore conveyance. 
     
     
         12 . A wellbore drill bit comprising: 
 a drill bit body having a longitudinal axis and defining an internal volume;   a plurality of stationary blades attached to the drill bit body and stationary with respect to the drill bit body, the plurality of stationary blades configured to drill through a subterranean formation to form a wellbore, the plurality of stationary blades spaced apart on an outer surface of the drill bit body to define a plurality of openings, each opening defined between two consecutively spaced apart stationary blades;   a plurality of expandable blades positioned in the respective plurality of openings, each expandable blade configured to drill through the subterranean formation to form the wellbore, each expandable blade configured to transition between a retracted state, in which each expandable blade is radially nearer to the longitudinal axis compared to each stationary blade, and an open state, in which each expandable blade extends radially away from the longitudinal axis to be radially farther away from the longitudinal axis compared to each stationary blade; and   a ball activation mechanism comprising: 
 a first piston positioned within the internal volume defined by the drill bit body, the first piston defining a first ball seat, and 
 a second piston positioned within the internal volume defined by the drill bit body, the second piston axially offset from the first piston, the second piston defining a second ball seat, wherein, in response to receiving a first ball and a second ball in the first ball seat and the second ball seat, respectively, the first piston and the second piston are configured to axially move causing the plurality of expandable blades to radially move between the retracted state and the open state. 
   
     
     
         13 . The wellbore drill bit of  claim 12 , further comprising a plurality of pads positioned within the internal volume defined by the drill bit body, the plurality of pads connected to the plurality of expandable blades, the plurality of pads configured to move axially within the internal volume defined by the drill bit body. 
     
     
         14 . The wellbore drill bit of  claim 13 , wherein the plurality of pads are connected to the second piston, wherein the plurality of pads are configured to move axially in response to axial movement of the second piston. 
     
     
         15 . The wellbore drill bit of  claim 13 , wherein the plurality of pads are in contact with the plurality of expandable blades, wherein the plurality of expandable blades are configured to radially move in response to axial movement of the plurality of pads. 
     
     
         16 . A method comprising: 
 while drilling a wellbore through a subterranean formation using a wellbore drill bit defining an internal volume, the wellbore drill bit including a plurality of stationary blades: 
 flowing, with a wellbore fluid, a first ball into the internal volume defined by the wellbore drill bit; 
 receiving, by a first ball seat formed in a first piston positioned within the internal volume defined by the wellbore drill bit, the first ball to prevent flow of wellbore fluid past the first piston; 
 in response to preventing the flow of wellbore fluid past the first piston, redirecting, by the first piston, the wellbore fluid towards a plurality of pads positioned within the internal volume defined by the wellbore drill bit; 
 moving, by the plurality of pads, in an axial direction in response to the redirected flow of the wellbore fluid, wherein the plurality of pads contact a plurality of expandable blades positioned within the internal volume defined by the wellbore drill bit;  
 in response to moving, by the plurality of pads, in the axial direction, moving, by the plurality of expandable blades, in a radially outward direction out of the internal volume defined by the wellbore drill bit, by the plurality of pads, in the axial direction, wherein the plurality of expandable pads extend past the plurality of stationary blades of the wellbore drill bit; and 
 enlarging, by the plurality of expandable blades, the wellbore by rotating within the wellbore. 
   
     
     
         17 . The method of  claim 16 , further comprising, after enlarging the wellbore: 
 flowing, with the wellbore fluid, a second ball into the internal volume defined by the wellbore drill bit;   receiving, by a second ball seat formed in a second piston positioned within the internal volume defined by the wellbore drill bit, the second ball to prevent flow of the wellbore fluid past the second piston, wherein the plurality of pads are connected to the second piston;   in response to preventing the flow of the wellbore fluid past the second piston, moving, by the second piston, in an axial direction towards the first piston; and   in response to the second piston moving in the axial direction towards the first piston, moving, by the expandable blades, in a radially inward direction into the internal volume defined by the wellbore drill bit.   
     
     
         18 . The method of  claim 17 , wherein the first piston is downstream of the second piston. 
     
     
         19 . The method of  claim 17 , wherein the first ball seat is smaller than the second ball seat. 
     
     
         20 . The method of  claim 17 , wherein the first ball is smaller than the second ball.