Cutting structures for fixed cutter drill bit and other downhole cutting tools

Abstract

A downhole cutting tool may include a tool body; a plurality of blades extending azimuthally from the tool body; and a plurality of cutting elements disposed on the plurality of blades, the plurality of cutting elements comprising: at least two non-planar cutting elements comprising a substrate and a diamond layer having a non-planar cutting end, wherein at least one of the at least two conical cutting elements has a positive back rake angle or positive side rake angle, and at least one of the at least two non-planar cutting elements has a negative back rake angle or a negative side rake angle.

1 .- 33 . (canceled) 
     
     
         34 . A drill bit for drilling a borehole in earth formations, comprising:
 a bit body having a bit axis and a bit face;   a plurality of blades extending radially along the bit face;   a plurality of cutting elements disposed on the plurality of blades, and   a coring cutting element having a cutting end terminating in an apex disposed in a region between at least two blades,   wherein the apex of the coring cutting element is at a height H less than a cutting edge of the most radially interior cutting element, wherein H ranges up to 0.35 times a diameter of the bit.   
     
     
         35 . The drill bit of  claim 34 , wherein H is up to 0.1 times the bit diameter. 
     
     
         36 . The drill bit of  claim 34 , wherein a ratio of H to a diameter of the coring cutting element ranges from 0.5 to 3. 
     
     
         37 . The drill bit of  claim 34 , where the coring cutting element has a cone angle ranging from 60 to 120 degrees. 
     
     
         38 . The drill bit of  claim 34 , where the coring cutting element is disposed along the bit axis. 
     
     
         39 . The drill bit of  claim 34 , where the coring cutting element is adjacent the bit axis. 
     
     
         40 . The drill bit of  claim 34 , wherein the apex is rounded. 
     
     
         41 . The drill bit of  claim 40 , wherein the apex has a radius of curvature ranging from 0.05 to 0.20 inch. 
     
     
         42 . The drill bit of  claim 34 , wherein the apex has a beveled surface. 
     
     
         43 . A downhole cutting tool, comprising:
 a tool body;   a central axis extending axially through the tool body;   a coring cutting element having a cutting end terminating in an apex, where the coring cutting element is disposed on the tool body within a central region defined by a radius around the central axis equal to three times a diameter of the coring cutting element; and   a plurality of cutting elements disposed on the tool body, where a portion of a cutting element radially closest to the coring cutting element that is configured to interact with a formation is at a height greater than the apex of the coring cutting element.   
     
     
         44 . The downhole tool of  claim 43 , wherein the coring cutting element is disposed on the tool body at the central axis. 
     
     
         45 . The downhole tool of  claim 43 , wherein the coring cutting element is disposed on the tool body adjacent the central axis. 
     
     
         46 . The downhole tool of  claim 43 , wherein the height ranges up to 0.35 times a diameter of the bit. 
     
     
         47 . The downhole tool of  claim 43 , further comprising a plurality of blades extending azimuthally from the tool body and converging towards the central region. 
     
     
         48 . The downhole tool of  claim 47 , wherein at least a portion of the plurality of blades comprises a diamond impregnated matrix material. 
     
     
         49 . The downhole tool of  claim 47 , wherein the plurality of cutting elements is disposed on the plurality of blades. 
     
     
         50 . The downhole tool of  claim 43 , wherein the plurality of cutting elements includes at least one cutter having a substrate and a diamond table having a substantially planar cutting face. 
     
     
         51 . The downhole tool of  claim 43 , wherein the plurality of cutting elements includes at least two non-planar cutting elements comprising a substrate and a diamond layer having a non-planar cutting end. 
     
     
         52 . The downhole tool of  claim 43 , wherein a longitudinal axis of the coring cutting element is parallel with the central axis. 
     
     
         53 . The downhole tool of  claim 43 , wherein a longitudinal axis of the coring cutting element is angled with respect to the central axis.