Cutting elements for casing milling

Abstract

A downhole tool includes a tool body and at least one blade coupled to the tool body. Cutting elements are coupled to a forward surface of the blade, and each cutting element may include a flank face and a trailing face to collectively define the width of the cutting element. A cutting edge is formed at the intersection of the flank face and a front face of the cutting element. The trailing and flank faces of adjacent cutting elements may be inclined relative to each other to define a flank angle that may be between greater than 0° and 15°. Adjacent cutting elements may have a gap therebetween, even when there is contact between the adjacent cutting elements.

What is claimed is: 
     
         1 . A downhole tool comprising:
 a body;   a blade coupled to the body, the blade having a forward surface;   a first cutting element coupled to the forward surface of the blade, the first cutting element having a flank face and a trailing face; and   a second cutting element coupled to the forward surface of the blade, the second cutting element being axially adjacent the first cutting element and having a flank face and a trailing face, the flank face of the second cutting element defining a flank angle greater than 0° relative to the trailing face of the first cutting element.   
     
     
         2 . The downhole tool of  claim 1 , the flank face of the second cutting element defining a flank angle up to 15° relative to the trailing face of the first cutting element. 
     
     
         3 . The downhole tool of  claim 1 , each of the first and second cutting elements including:
 first and second sides;   a front face between the first and second sides and between the flank and trailing faces; and   a cutting edge at an intersection of the front and flank faces.   
     
     
         4 . The downhole tool of  claim 3 , each of the first and second cutting elements further including:
 a plurality of back-up cutting edges formed in the front face at an intersection of a back-up flank face and a rake face, the back-up cutting edge extending across a full length of the front face of the cutting element.   
     
     
         5 . The downhole tool of  claim 4 , a back-up flank angle being formed between the rake face of each back-up cutting edge and a line perpendicular to the front face. 
     
     
         6 . The downhole tool of  claim 5 , the back-up flank angle being equal to the flank angle. 
     
     
         7 . The downhole tool of  claim 1 , each of the first and second cutting elements further including:
 a trailing edge at an intersection between the trailing face and the front face, at least a portion of the trailing edge of the first cutting element contacting the flank face of the second cutting element.   
     
     
         8 . The downhole tool of  claim 7 , the trailing edge of the first cutting element being in full contact with the second cutting element. 
     
     
         9 . The downhole tool of  claim 1 , the first and second cutting elements defining a gap between the flank face of the second cutting element and the trailing face of the first cutting element. 
     
     
         10 . The downhole tool of  claim 1 , a width of the cutting element varying along a length of the cutting element. 
     
     
         11 . The downhole tool of  claim 1 , the first and second cutting elements each including a front face extending between the flank face and the trailing face, at least a portion of the front face of the first or second cutting element having at least one coating applied thereto. 
     
     
         12 . The downhole tool of  claim 1 , each of the first and second cutting elements having a width of 1 inch or less as measured from the flank face to the trailing face. 
     
     
         13 . A cutting element, comprising:
 a flank face;   a trailing face opposite the flank face and non-parallel to the flank face, a distance between the flank face and the trailing face defining a width of the cutting element;   a front face extending between the flank face and the trailing face;   a cutting edge at an intersection of the front face and the flank face; and   a trailing edge at an intersection of the trailing face and the front face.   
     
     
         14 . The cutting element of  claim 13 , a flank angle of the flank face being between greater than 0° to 15°. 
     
     
         15 . The cutting element of  claim 13 , further including:
 a plurality of teeth defining back-up cutting edges in the front face, each back-up cutting edge being at an intersection of a back-up flank face and a rake face, and having a back-up flank angle.   
     
     
         16 . The cutting element of  claim 15 , the back-up flank angle being equal to a flank angle of the flank face. 
     
     
         17 . The cutting element of  claim 15 , a transition between the back-up flank face and the rake face having at least one of a curved, angled, or planar shape. 
     
     
         18 . The cutting element of  claim 15 , a ratio of a tooth width of the plurality of teeth to the width of the cutting element being between 1:8 and 1:2. 
     
     
         19 . The cutting element of  claim 12 , the width of the cutting element being between 3/16 inch and ⅜ inch, and a thickness of the cutting element being between ⅛ inch and ½ inch. 
     
     
         20 . A method of milling, comprising:
 inserting a cutting tool into a wellbore, the cutting tool including a blade with a first and second cutting elements coupled thereto, the first and second cutting elements being axially adjacent with a gap therebetween, each of the first and second cutting elements including:
 a flank face; 
 a trailing face; 
 first and second sides; 
 a front face extending between the first and second sides, and between the flank and trailing faces; 
 a cutting edge at an intersection of the front face and the flank face; and 
 a trailing edge at an intersection of the trailing face and the front face; 
   engaging a casing with at least the first cutting element of the cutting tool; and   milling away a portion of the casing with at least the first cutting element.   
     
     
         21 . The method of  claim 20 , the gap being formed between the trailing face of the first cutting element and the flank face of the second cutting element. 
     
     
         22 . The method of  claim 20 , each of the first and second cutting elements further including one or more back-up teeth, wherein milling away the portion of the casing includes wearing down the flank face such that the cutting edge moves toward the one or more back-up teeth.