Cutter block for a downhole underreamer

Abstract

A downhole tool has a body with a bore formed at least partially therethrough. A cutter block may be coupled to the body and move radially outward from the body in response to an increased pressure in the bore. The cutter block may include an outer surface that transitions from a first portion to a second portion, with the first portion being downhole of the second portion. A radius of curvature between the first and second portions may be less than about 7 cm. The second portion or a line tangential thereto may be oriented at an angle from about 60° to about 120° with respect to a central longitudinal axis of the body. A plurality of cutting elements may be disposed on the outer surface of the cutter block. At least one of the cutting elements may be disposed at least partially on the first or second portion of the outer surface.

What is claimed is:  
     
         1 . A cutting tool, comprising:
 a body;   a cutter block coupled to the body and adapted to move radially outward from the body, the cutter block including an outer surface that transitions from a first portion to a second portion, the first portion and the second portion remaining stationary relative to each other with the first portion being downhole of the second portion, a radius of curvature between the first and second portions being less than about 7 cm, the second portion or a line tangential thereto being oriented at an angle from about 60° to about 120° with respect to a central longitudinal axis of the body; and   a plurality of cutting elements disposed on the outer surface of the cutter block, at least one of the plurality of cutting elements being disposed at least partially on the first or second portion of the outer surface.   
     
     
         2 . The cutting tool of  claim 1 , wherein the radius of curvature is less than about 5 cm, and wherein the angle is from about 75° to about 105°. 
     
     
         3 . The cutting tool of  claim 1 , wherein a first one of the cutting elements is at least partially disposed on the first portion of the outer surface of the cutter block, and wherein a second one of the cutting elements is at least partially disposed on the second portion of the outer surface of the cutter block. 
     
     
         4 . The cutting tool of  claim 3 , wherein the first portion of the outer surface of the cutter block is substantially parallel to the central longitudinal axis through the body. 
     
     
         5 . The cutting tool of  claim 1 , wherein a first distance between an apex of a cutting element closest to an inner surface of the cutter block and an apex of a cutting element farthest from the inner surface of the cutter block is from about 0.5 cm to about 10 cm, and wherein the first distance is measured in a direction perpendicular to the central longitudinal axis through the body. 
     
     
         6 . The cutting tool of  claim 5 , wherein a second distance between an apex of a cutting element closest to an end portion of the cutter block and an apex of a cutting element farthest from the end portion of the cutter block is from about 2 cm to about 20 cm, and wherein the second distance is measured in a direction parallel to the central longitudinal axis through the body. 
     
     
         7 . The cutting tool of  claim 6 , wherein a ratio of the first distance to the second distance is from about 1:1 to about 1:10. 
     
     
         8 . The cutting tool of  claim 1 , wherein an angle between a central longitudinal axis extending through a first one of the cutting elements and an X-axis in an X-Y plane is from about −90° to about 90°, the X-axis being aligned with a length of the cutter block, and a Y-axis being aligned with a height of the cutter block. 
     
     
         9 . The cutting tool of  claim 1 , wherein an angle between a central longitudinal axis extending through a first one of the cutting elements and an X-axis in an X-Z plane is from about −90° to about 45°, the X-axis being aligned with a length of the cutter block, and a Z-axis being aligned with a width of the cutter block. 
     
     
         10 . The cutting tool of  claim 1 , wherein an angle between a central longitudinal axis extending through a first one of the cutting elements and an Y-axis in an Y-Z plane is from about −45° to about 90°, the Y-axis being aligned with a height of the cutter block, and a Z-axis being aligned with a width of the cutter block. 
     
     
         11 . A downhole tool, comprising:
 a body;   a cutter block coupled to the body and adapted to move radially outward from the body, the cutter block including an outer surface that transitions from a first portion to a second portion, the first portion and the second portion remaining stationary relative to each other with the first portion defined as being downhole of the second portion, an angle between the first portion or a line tangential thereto and the second portion or a line tangential thereto being from about 60° to about 120°, the second portion or the line tangential thereto being oriented at an angle from about 60° to about 120° with respect to a central longitudinal axis of the body; and   a plurality of cutting elements disposed on the outer surface of the cutter block, at least one of the plurality of cutting elements being disposed at least partially on the second portion of the outer surface.   
     
     
         12 . The downhole tool of  claim 11 , wherein the angle between the first portion or the line tangential thereto and the second portion or the line tangential thereto is from about 75° to about 105°. 
     
     
         13 . The downhole tool of  claim 11 , wherein the angle between the second portion or the line tangential thereto and the central longitudinal axis of the body is from about 75° to about 105°. 
     
     
         14 . The downhole tool of  claim 11 , further comprising another one of the plurality of cutting elements is at least partially disposed on the first portion of the outer surface of the cutter block. 
     
     
         15 . The downhole tool of  claim 11 , wherein the first portion of the outer surface of the cutter block is substantially parallel to the central longitudinal axis through the body. 
     
     
         16 . A downhole tool, comprising:
 a body;   a cutter block coupled to the body and adapted to move radially outward from the body,   a plurality of cutting elements disposed at least partially on the outer surface of the cutter block, at least 50% of the cutting elements being positioned between first and second points along a length of the cutter block, a distance between the first and second points being 30% of the length of the cutter block, and the first point being at an end portion of the cutter block.   
     
     
         17 . The downhole tool of  claim 16 , wherein the first point is at a downhole end portion of the cutter block. 
     
     
         18 . The downhole tool of  claim 16 , wherein at least 80% of the cutting elements are positioned between the first and second points, and wherein the distance is 20% of the length of the cutter block. 
     
     
         19 . The downhole tool of  claim 16 , wherein the outer surface transitions from a first portion to a second portion, the first portion being downhole of the second portion, a radius of curvature between the first and second portions being less than about 7 cm, the second portion or a line tangential thereto being oriented at an angle from about 60° to about 120° with respect to a central longitudinal axis of the body, and at least one of the cutting elements being disposed at least partially on the second portion of the outer surface. 
     
     
         20 . The downhole tool of  claim 16 , wherein the outer surface transitions from a first portion to a second portion, the first portion being downhole of the second portion, an angle between the first portion or a line tangential thereto and the second portion or a line tangential thereto being from about 60° to about 120°, the second portion or the line tangential thereto being oriented at an angle from about 60° to about 120° with respect to a central longitudinal axis of the body, and at least one of the cutting elements being disposed at least partially on the second portion of the outer surface.