Modified cutters and a method of drilling with modified cutters

Abstract

A cutter for a drag bit may include a substrate and an ultrahard layer on an end surface of the substrate. The ultrahard layer may include an exposed surface having at least three depressions extending from an interior of the exposed surface radially outward to a peripheral edge formed between the working surface and a side surface of the ultrahard layer, the at least three depressions separated from each other by at least three raised regions forming an apex of the exposed surface, the at least three raised regions connected to each other proximate the central axis and extending from proximate the central axis to the peripheral edge. Other working surfaces are also included.

What is claimed: 
     
         1 . A cutter, comprising:
 a substrate; and   an ultrahard layer on an end surface of the substrate, the ultrahard layer including a central axis and an exposed surface having at least three depressions extending from an interior of the exposed surface radially outward to a peripheral edge formed between the working surface and a side surface of the ultrahard layer, the at least three depressions separated from each other by at least three raised regions forming an apex of the exposed surface, the at least three raised regions connected to each other proximate the central axis and extending from proximate the central axis to the peripheral edge.   
     
     
         2 . The cutter of  claim 1 , wherein at least one raised region has a width that varies on a length of the raised region. 
     
     
         3 . The cutter of  claim 1 , wherein the peripheral edge undulates between the at least three raised regions and the at least three depressions. 
     
     
         4 . The cutter of  claim 1 , wherein the peripheral edge extends to an outer diameter of the cutter. 
     
     
         5 . The cutter of  claim 1 , wherein the at least three raised ridges comprise a flat region extending from a first portion of the peripheral edge to the central axis. 
     
     
         6 . The cutter of  claim 1 , wherein the at least three depressions have a concave curvature. 
     
     
         7 . The cutter of  claim 1 , wherein the apex comprises a convex curvature. 
     
     
         8 . The cutter of  claim 1 , wherein the peripheral edge has a varied geometry around at least a portion of the periphery of the exposed top surface. 
     
     
         9 . A fixed cutter drill bit comprising a body having the cutter as recited in  claim 1  mounted thereon. 
     
     
         10 . A cutter for a drag bit, the cutter comprising:
 a substrate;   an ultrahard layer on an end surface of the substrate, the ultrahard layer including an exposed top surface surrounded by a peripheral edge, the exposed top surface comprising:
 an apex extending from the first cutting edge to another portion of the peripheral edge, wherein the exposed top surface decreases in height away from the apex to other portions of the peripheral edge which have a lower overall height than the height of the apex, 
 wherein the apex has a width that varies along its length. 
   
     
     
         11 . The cutter of  claim 10 , wherein the apex comprises a convex curvature. 
     
     
         12 . The cutter of  claim 10 , wherein the exposed top surface has a concave curvature as it decreases in height away from the apex. 
     
     
         13 . The cutter of  claim 10 , wherein the peripheral edge has a varied geometry around at least a portion of the periphery of the exposed top surface. 
     
     
         14 . The cutter of  claim 10 , wherein the apex comprises a flat region extending from the first cutting edge to the other portion of the peripheral edge. 
     
     
         15 . A fixed cutter drill bit comprising a body having the cutter as recited in  claim 10  mounted thereon. 
     
     
         16 . A cutter, comprising:
 a substrate;   an ultrahard layer on an end surface of the substrate, the ultrahard layer including an exposed dome shaped top surface surrounded by a peripheral edge, the dome shaped exposed top surface comprising:
 an apex extending from the first cutting edge to another portion of the peripheral edge, wherein the exposed top surface decreases in height away from the apex to other portions of the peripheral edge which have a lower overall height than the height of the apex. 
   
     
     
         17 . The cutter of  claim 16 , wherein the apex comprises a convex curvature. 
     
     
         18 . The cutter of  claim 16 , wherein the exposed top surface has a concave curvature as it decreases in height away from the apex. 
     
     
         19 . The cutter of  claim 16 , wherein the peripheral edge has a varied geometry around at least a portion of the periphery of the exposed top surface. 
     
     
         20 . A fixed cutter drill bit comprising a body having the cutter as recited in  claim 16  mounted thereon.