Downhole cutting tools having hybrid cutting structures

Abstract

A drill bit is disclosed, wherein the drill bit has a bit body with a longitudinal axis extending there through and a bit face. A plurality of blades extends from the bit body, wherein the plurality of blades has a blade profile including a nose. A plurality of cutting elements are disposed on the plurality of blades, including a plurality of non-planar cutting elements and a plurality of rotatable cutting elements, wherein the plurality of non-planar cutting elements are disposed in a non-planar cutting element region on at least one of the blades between the longitudinal axis and the nose

What is claimed is: 
     
         1 . A drill bit, comprising:
 a bit body having a longitudinal axis extending there through and a bit face;   a plurality of blades extending from the bit body, wherein the plurality of blades has a blade profile comprising a nose;   a plurality of cutting elements disposed on the plurality of blades, the plurality of cutting elements comprising:
 a plurality of non-planar cutting elements; and 
 a plurality of rotatable cutting elements; 
 wherein the plurality of non-planar cutting elements are disposed in a non-planar cutting element region on at least one of the blades between the longitudinal axis and the nose. 
   
     
     
         2 . The drill bit of  claim 1 , wherein the plurality of non-planar cutting elements have a cutting end with a conical, convex, or concave side surface terminating in a rounded apex. 
     
     
         3 . The drill bit of  claim 2 , wherein the plurality of non-planar cutting elements comprise a plurality of conical cutting elements. 
     
     
         4 . The drill bit of  claim 3 , wherein the plurality of conical cutting elements has a back rake angle ranging from −35 to 35. 
     
     
         5 . The drill bit of  claim 1 , wherein at least one rotatable cutting element comprises a substantially planar cutting face. 
     
     
         6 . The drill bit of  claim 1 , further comprising a center coring cutting element having a pointed end disposed in a region between at least two blades. 
     
     
         7 . The drill bit of  claim 1 , wherein a first radial cutting element disposed on a blade comprises an angle formed between the most radially interior portion of the first radial cutting element and a line parallel to the bit longitudinal axis, wherein the angle is greater than zero. 
     
     
         8 . The drill bit of  claim 1 , wherein the plurality of rotatable cutting elements is disposed in a rotatable cutting element region adjacent to the non-planar cutting element region. 
     
     
         9 . The drill bit of  claim 1 , wherein the plurality of rotatable cutting elements is disposed in a rotatable cutting element region overlapping with the non-planar cutting element region when viewed in a rotated profile view. 
     
     
         10 . The drill bit of  claim 1 , wherein at least one non-planar cutting element is rotatably retained to a blade. 
     
     
         11 . The drill bit of  claim 1 , wherein at least one fixed cutter is disposed in a gage region of the blade profile. 
     
     
         12 . The drill bit of  claim 1 , wherein at least one of the plurality of blades includes only non-planar cutting elements disposed thereon. 
     
     
         13 . The drill bit of  claim 1 , wherein at least one of the plurality of blades includes only rotatable cutting elements disposed thereon. 
     
     
         14 . A downhole cutting tool, comprising:
 a tool body having a longitudinal axis extending there through and a cutting end;   a plurality of blades extending from the tool body;   a plurality of cutting elements disposed on the plurality of blades, the plurality of cutting elements comprising:
 at least one rotatable cutting element; and 
 at least one non-planar cutting element; 
 wherein the at least one non-planar cutting element is in a non-planar cutting element region of the blades closest to the cutting end. 
   
     
     
         15 . The drill bit of  claim 14 , wherein the plurality of non-planar cutting elements have a cutting end with a conical, convex, or concave side surface terminating in a rounded apex. 
     
     
         16 . The drill bit of  claim 15 , wherein the plurality of non-planar cutting elements comprise a plurality of conical cutting elements. 
     
     
         17 . The cutting tool of  claim 14 , wherein the at least one rotatable cutting element and the at least one non-planar cutting element are on the same blade. 
     
     
         18 . The cutting tool of  claim 14 , wherein the at least one rotatable cutting element is disposed in a rotatable cutting element region adjacent to the non-planar cutting element region. 
     
     
         19 . The cutting tool of  claim 14 , wherein the at least one rotatable cutting element is disposed in a rotatable cutting element region overlapping with the non-planar cutting element region when viewed in a rotated profile view. 
     
     
         20 . The cutting tool of  claim 14 , wherein the cutting tool is a bi-center bit comprising a pilot section and a reamer section longitudinally offset from the pilot section, and wherein the plurality of blades comprise pilot blades extending from the pilot section of the tool body and reamer blades extending from the reamer section of the tool body. 
     
     
         21 . The cutting tool of  claim 20 , wherein the at least one non-planar cutting element is disposed on the pilot blades and the at least one rotatable cutting element is disposed on the reamer blades. 
     
     
         22 . The cutting tool of  claim 20 , wherein at least one non-planar cutting element is disposed on the reamer blades in a non-planar cutting element region closest to the cutting end and at least one rotatable cutting element is disposed in a rotatable cutting element region adjacent to the non-planar cutting element region. 
     
     
         23 . The cutting tool of  claim 14 , wherein the cutting tool is a hole enlargement tool. 
     
     
         24 . The cutting tool of  claim 14 , wherein at least one non-planar cutting element is rotatably retained on a blade. 
     
     
         25 . The cutting tool of  claim 14 , wherein at least one of the plurality of blades includes only non-planar cutting elements disposed thereon. 
     
     
         26 . The cutting tool of  claim 14 , wherein at least one of the plurality of blades includes only rotatable cutting elements disposed thereon.