Adjustable drill string reamer

Abstract

A wellbore assembly includes a drill string, a drill bit, and a reamer assembly. The reamer assembly is coupled to the drill string uphole of the drill bit and includes a side cutter. The reamer assembly includes a spring that moves the side cutter from an extended position, in which the side cutter is retained by a portion of the reamer assembly against inward movement and in which the cutter defines a first drilling diameter greater than a drilling diameter of the drill bit, to a retracted position in which the portion of the reamer assembly has been broken by a shear force applied by the side cutter under a weight on bit applied against an inner component of the casing. In the retracted position, the side cutter is housed within the housing and defines a drilling diameter equal to or less than the drilling diameter of the drill bit.

1 . A wellbore assembly, comprising:
 a drill string configured to be disposed within a wellbore comprising a casing;   a drill bit coupled to a downhole end of the drill string; and   a reamer assembly coupled to the drill string and residing uphole of the drill bit; the reamer assembly comprising:
 a side cutter coupled to a wall of the drill string, and 
 a tension spring attached to the drill string and to the side cutter, the tension spring arranged to bias the side cutter toward a side cutter housing configured to house the side cutter such that the tension spring moves the side cutter from an extended position, in which the side cutter is retained by a portion of the reamer assembly against inward movement toward the side cutter housing and in which the side cutter defines a first drilling diameter greater than a drilling diameter of the drill bit, to a retracted position in which the portion of the reamer assembly has been broken, the portion of the reamer assembly configured to break under shear force applied by the side cutter bearing against an inner component of the casing that pushes, under a weight on bit applied in a downhole direction against the inner component, the side cutter inwardly until the side cutter breaks the portion of the reamer assembly to retract the side cutter, and in which the side cutter is housed within the side cutter housing with the side cutter defining a second drilling diameter less than the first drilling diameter. 
   
     
     
         2 . The wellbore assembly of  claim 1 , wherein the portion of the reamer assembly comprises a shear pin attached to the side cutter housing and disposed within an aperture of the side cutter to retain, with the side cutter in the extended position, the side cutter against inward movement toward the side cutter housing. 
     
     
         3 . The wellbore assembly of  claim 2 , wherein the shear pin defines a length that extends perpendicular with respect to a direction of the shear force applied by the side cutter. 
     
     
         4 . The wellbore assembly of  claim 1 , wherein the inner component of the casing comprises an inner rim of an open hole packer, the inner rim comprising an inner diameter less than the first drilling diameter of the side cutter such that a cutting face of the side cutter is arranged to bear, with the side cutter in the extended position, against the rim of the open hole packer. 
     
     
         5 . The wellbore assembly of  claim 4 , wherein the portion of the reamer assembly is configured to break under a shear force applied by the side cutter bearing against the inner rim of the open hole packer as the drill bit is pushed downhole from a surface of the wellbore. 
     
     
         6 . The wellbore assembly of  claim 4 , wherein the casing comprises a drillable float assembly disposed uphole of the open hole packer after a cementing operation, the drillable float assembly comprising a float shoe and a float collar and the drill bit is configured to cut, together with the side cutter in the extended position, the drillable float assembly to reach the open hole packer. 
     
     
         7 . The wellbore assembly of  claim 1 , wherein the tension spring is attached to an inner surface of the side cutter housing and pulls the side cutter toward the side cutter housing. 
     
     
         8 . The wellbore assembly of  claim 1 , wherein the side cutter is arranged, in the extended position and the retracted position, at a common angle with respect to a central longitudinal axis of the drill string. 
     
     
         9 . The wellbore assembly of  claim 1 , further comprising one or more additional side cutters evenly distributed along a circumference of the drill string and configured to move from an extended position to a retracted position by a respective tension spring. 
     
     
         10 . The wellbore assembly of  claim 1 , wherein the reamer assembly comprises a latch configured to latch onto the side cutter in the retracted position to prevent the side cutter from moving from the retracted position. 
     
     
         11 . A wellbore assembly, comprising:
 a drill string configured to be disposed within a wellbore;   a side cutter coupled to a wall of the drill string and disposed uphole of a drill bit of the drill string; and   a retaining member coupled to the drill string and to the side cutter, the retaining member arranged to retain the side cutter in an extended position and prevent the side cutter from moving inwardly toward a housing configured to house at least part of the side cutter, the retaining member configured to break under a shear force applied by the side cutter bearing against a portion of the wellbore comprising a reduced diameter that biases, under a weight on bit applied in a downhole direction against the inner component, the side cutter inwardly until the side cutter breaks the retaining member to allow the side cutter to move to a retracted position in which the side cutter is at least partially housed within the housing, the side cutter defining, in the extend position, a first drilling diameter greater than a drilling diameter of the drill bit, and the side cutter defining, in the retracted position, a second drilling diameter less than the first drilling diameter and such that the drill string is able to drift through the portion of the wellbore comprising the reduced diameter.   
     
     
         12 . The wellbore assembly of  claim 11 , further comprising a biasing member attached to the drill string and to the side cutter, the biasing member arranged to urge the side cutter toward the housing to move the side cutter from the extended position to the retracted position, and wherein the retaining member comprises a shear pin attached to the side cutter housing and disposed within an aperture of the side cutter. 
     
     
         13 . The wellbore assembly of  claim 11 , wherein the portion of the wellbore comprises an inner rim of an open hole packer, the inner rim comprising an inner diameter less than the first drilling diameter of the side cutter such that a cutting face of the side cutter is arranged to bear, with the side cutter in the extended position, against the rim of the open hole packer. 
     
     
         14 . The wellbore assembly of  claim 13 , wherein the retaining member is configured to break under a shear force applied by the side cutter bearing against the inner rim of the open hole packer as the drill bit is pushed downhole from a surface of the wellbore. 
     
     
         15 . The wellbore assembly of  claim 11 , wherein the casing comprises a drillable float assembly disposed uphole of the open hole packer after a cementing operation, the drillable float assembly comprising a float shoe and a float collar and the drill bit is configured to cut, together with the side cutter in the extended position, the drillable float assembly to reach the open hole packer. 
     
     
         16 . The wellbore assembly of  claim 11 , further comprising a biasing attached to an inner surface of the side cutter housing and configured to pull the side cutter toward the side cutter housing. 
     
     
         17 . The wellbore assembly of  claim 1 , wherein the second drilling diameter of the side cutter is equal to or less than the drilling diameter of the drill bit. 
     
     
         18 . The wellbore assembly of  claim 11 , wherein the reamer assembly comprises a latch configured to latch onto the side cutter in the retracted position to prevent the side cutter from moving from the retracted position. 
     
     
         19 . A method, comprising:
 drilling, with a drill string disposed inside a wellbore comprising a casing and an open hole packer attached to the casing, a drillable wellbore component, the drill string comprising a drill bit and a reamer assembly residing uphole of the drill bit, the reamer assembly comprising i) a side cutter coupled to the drill string and ii) a retaining member coupled to the drill string and to the side cutter, the retaining member arranged to retain the side cutter in an extended position and prevent the side cutter from moving inwardly toward a housing configured to house at least part of the side cutter, the retaining member configured to break under a shear force applied by the side cutter bearing against a portion of the wellbore comprising a reduced diameter that biases, under a weight on bit applied in a downhole direction against the inner component, the side cutter inwardly until the side cutter breaks the retaining member to allow the side cutter to move to a retracted position in which the side cutter is at least partially housed within the housing, the side cutter defining, in the extend position, a first drilling diameter greater than a drilling diameter of the drill bit, and the side cutter defining, in the retracted position, a second drilling diameter less than the first drilling diameter and such that the drill string is able to drift pass the portion of the wellbore comprising the reduced diameter;   applying weight on the drill string to push the side cutter against an inwardly projecting shoulder of the open hole packer until the retaining member breaks under a shear force applied by the side cutter bearing against the inwardly projecting shoulder of the open hole packer and the side cutter moves, with the retaining member broken, to the retracted position; and   moving, with the side cutter in the retracted portion, the drill bit and side cutters through the casing past the open hole packer to continue to drill downhole of the open hole packer.   
     
     
         20 . The method of  claim 19 , further comprising, before drilling the drillable wellbore component, cementing the casing on the wellbore, wherein the drillable wellbore component comprises a float shoe disposed inside the casing and an open hole packer attached to the casing and disposed downhole of the float shoe.