Modified cutters and a method of drilling with modified cutters

Abstract

A cutter for a fixed cutter drill bit including a substrate and an ultrahard material layer disposed on an end surface of the substrate, the ultra hard material layer having an upper surface opposite the substrate end surface and a peripheral surface such that the upper surface intersects the peripheral surface along a peripheral edge. The peripheral edge continuously increases and decreases in height as measured from a plane perpendicular to a longitudinal axis of the cutter.

What is claimed is: 
     
       1. A cutter for a fixed cutter drill bit for cutting earth formations, the cutter comprising:
 a substrate for mounting on said bit, said substrate having a periphery, an end surface, a longitudinal axis extending through said end surface; and 
 an ultra hard material disposed on the end surface, said ultra hard material layer comprising an exposed upper surface opposite said end surface and a peripheral surface, wherein said ultra hard material upper surface intersects said ultra hard material peripheral surface along a peripheral edge wherein said peripheral edge continuously decreases and increases in height as measured from a first plane perpendicular to said longitudinal axis, wherein a second plane along said longitudinal axis intersects said peripheral edge at a first point and a second point and wherein a third plane along said longitudinal axis and perpendicular to said second plane intersects said peripheral edge at a third point and a fourth point, wherein said peripheral edge has a first convex portion extending from said first point in a direction toward said third point and a first concave portion from said first convex portion to said third point, wherein said peripheral edge has a second concave portion extending from said third point in a direction toward said second point and a second convex portion extending from said second concave portion to said second point, wherein said peripheral edge has a third convex portion extending from said second point in a direction toward said fourth point and a third concave portion extending from said third convex portion to said fourth point, and wherein said peripheral edge has a fourth concave portion extending from said fourth point in a direction toward said first point and a fourth convex portion extending from said fourth concave portion to said first point, wherein the first concave portion and the second concave portion define a first continuous concave curve, wherein the second convex portion and the third convex portion define a first continuous convex curve, wherein the third concave portion and the fourth concave portion define a second continuous concave curve and wherein the fourth convex portion and the first convex portion define a second continuous convex curve. 
 
     
     
       2. The cutter as recited in  claim 1  wherein said first and second points are at a same height as measured from said first plane and wherein said third and fourth points are at a same height as measured from said first plane. 
     
     
       3. The cutter as recited in  claim 2  wherein said first and second points are at maximum height of said peripheral edge as measured from said first plane and wherein said third and fourth points are at minimum height of said peripheral edge as measured from said first plane. 
     
     
       4. A fixed cutter drill bit comprising a body having the cutter as recited in  claim 3  mounted thereon. 
     
     
       5. A fixed cutter drill bit comprising a body having the cutter as recited in  claim 1  mounted thereon. 
     
     
       6. A cutter for a fixed cutter drill bit, the cutter comprising:
 a base portion for mounting on said fixed cutter drill bit; and   an ultrahard layer disposed on the base portion, the ultrahard layer comprising an exposed side surface and an exposed top surface surrounded by a peripheral edge formed at the intersection of the exposed side surface and exposed top surface, the exposed top surface comprising:
 a cutting face extending a height above the base portion along a portion of the peripheral edge to form a first cutting edge portion along the peripheral edge; and 
 an apex extending from the first cutting edge to another portion of the peripheral edge, 
 the exposed top surface, adjacent the first cutting edge and the apex and extending from opposite sides of the apex, decreases in height in opposite directions away from the cutting face to other portions of the peripheral edge which have a lower overall height than the height of the cutting face and the first cutting edge portion such that at least a portion of the exposed top surface extending away from the apex has a convex curvature and such that the exposed side surface at the cutting edge has a greater height than the exposed side surface adjacent the other portions of the peripheral edge having the lower overall height, wherein said cutting face comprises at least a portion of the apex. 
   
     
     
       7. The cutter of claim 6, wherein the cutting face comprises a beveled edge around at least a portion of the periphery of the cutter. 
     
     
       8. The cutter of claim 7, wherein the cutting face comprises a beveled edge which extends less than a full periphery of the cutter. 
     
     
       9. The cutter of claim 7, wherein the beveled edge ranges from about 0.005 inches to about 0.050 inches. 
     
     
       10. The cutter of claim 6, wherein the at least one cutting face comprises a first cutting face and a second cutting face, wherein each extends to a height above the base portion along a portion of the peripheral edge to form the first cutting edge and a second cutting edge, respectively, and wherein the apex extends between the first and second cutting edges. 
     
     
       11. The cutter of claim 6, wherein the apex comprises a flat region extending from the first cutting edge to the other portion of the peripheral edge. 
     
     
       12. The cutter of claim 6, wherein a portion of the exposed top surface extending away from the apex has a concave curvature. 
     
     
       13. The cutter of claim 6, wherein the apex comprises a convex curvature. 
     
     
       14. A fixed cutter drill bit comprising a body having the cutter as recited in claim 6 mounted thereon. 
     
     
       15. A cutter for a fixed cutter drill bit, the cutter comprising:
 a base portion for mounting on the fixed cutter drill bit; and   an ultrahard layer disposed on the base portion comprising an exposed top surface surrounded by a peripheral edge, the exposed top surface comprising:
 a cutting face extending a height above the base portion along a portion of the peripheral edge to form a first cutting edge portion along the peripheral edge; and 
 an apex extending from the first cutting edge to another portion of the peripheral edge, where the exposed top surface, adjacent the first cutting edge and the apex and extending from opposite sides of the apex, decreases in height in opposite directions away from the cutting face and the first cutting edge portion to other portions of the peripheral edge which have a lower overall height than the height of the cutting face, wherein the cutting face comprises at least a portion of the apex; 
 wherein the peripheral edge has a beveled edge around at least a portion of the periphery of the exposed top surface, the beveled edge creating a varied edge geometry around at least a portion of the periphery of the exposed top surface. 
   
     
     
       16. The cutter of claim 15, wherein the varied edge geometry comprises a varied bevel width. 
     
     
       17. The cutter of claim 16, wherein the varied bevel width increases along a portion of the edge extending in either direction away from the first cutting edge. 
     
     
       18. The cutter of claim 16, wherein the varied bevel width decreases along a portion of the edge extending in either direction away from the first cutting edge. 
     
     
       19. The cutter of claim 15, wherein the varied edge geometry comprises a varied bevel angle. 
     
     
       20. The cutter of claim 15, wherein the apex comprises a flat region extending from the first cutting edge to the other portion of the peripheral edge. 
     
     
       21. The cutter of claim 15, wherein the apex comprises a convex curvature. 
     
     
       22. A fixed cutter drill bit comprising a body having the cutter as recited in claim 15 mounted thereon. 
     
     
       23. The cutter of claim 15, wherein the peripheral edge has the varied edge geometry adjacent the apex. 
     
     
       24. A fixed cutter drill bit, comprising:
 a bit body having a bit axis and a direction of rotation about the bit axis;   at least one blade extending from the bit body, the at least one blade having a leading face facing the direction of rotation of the bit body about the bit axis, a trailing face facing away from the direction of rotation of the bit body about the bit axis, and a formation facing surface extending between the leading face and the trailing face, the at least one blade having at least one cutter pocket formed therein, the at least one cutter pocket opening to the leading face of the at least one blade; and   at least one cutting element attached to the at least one cutter pocket, the at least one cutting element comprising:
 a base portion; and 
 an ultrahard layer on the base portion comprising an exposed top surface surrounded by a peripheral edge, the exposed top surface extending a height above the base portion along a portion of the peripheral edge to form a first cutting edge portion along the peripheral edge and the exposed top surface decreasing in height in a direction away from the height of the first cutting edge towards the base portion to another portion of the peripheral edge that has a lower overall height than the height of the cutting edge. 
   
     
     
       25. The fixed cutter drill bit of claim 24, wherein the peripheral edge has a varied geometry around at least a portion of the periphery of the exposed top surface. 
     
     
       26. The fixed cutter drill bit of claim 25, wherein the varied geometry comprises a varied bevel width. 
     
     
       27. The fixed cutter drill bit of claim 26, wherein the varied bevel width increases along a portion of the edge extending in either direction away from the first cutting edge. 
     
     
       28. The fixed cutter drill bit of claim 25, wherein the varied geometry comprises a beveled edge which extends less than a full periphery of the cutter. 
     
     
       29. The fixed cutter drill bit of claim 24, wherein the exposed surface further comprises an apex extending from the first cutting edge to another portion of the peripheral edge, and wherein the exposed surface decreases in height away from the apex. 
     
     
       30. The fixed cutter drill bit of claim 29, wherein the apex comprises a flat region extending from the first cutting edge to the other portion of the peripheral edge. 
     
     
       31. The fixed cutter drill bit of claim 29, wherein the apex comprises a convex curvature. 
     
     
       32. The fixed cutter drill bit of claim 29, wherein the peripheral edge has a varied geometry adjacent the apex. 
     
     
       33. The fixed cutter drill bit of claim 29, further comprising a plurality of cutting elements that form a cutter profile, wherein the at least one cutting element is oriented in the at least one cutter pocket such that the apex is aligned to be substantially perpendicular to the cutter profile. 
     
     
       34. A fixed cutter drill bit, comprising:
 a bit body having a bit axis and a direction of rotation about the bit axis;   at least one blade extending from the bit body, the at least one blade having a leading face facing the direction of rotation of the bit body about the bit axis, a trailing face facing away from the direction of rotation of the bit body about the bit axis, and a formation facing surface extending between the leading face and the trailing face, the at least one blade having at least one cutter pocket formed therein, the at least one cutter pocket opening to the leading face of the at least one blade; and   at least one cutting element attached to the at least one cutter pocket, the at least one cutting element comprising:
 a base portion; and 
 an ultrahard layer on the base portion comprising an exposed top surface surrounded by a peripheral edge, the exposed top surface extending a height above the base portion to an apex that extends from a first region of the peripheral edge forming first cutting edge portion along the peripheral edge to another region of the peripheral edge and peripheral edge being a continuously curved edge that decreases in height in a direction away from the height of the first cutting edge. 
   
     
     
       35. The fixed cutter drill bit of claim 34, further comprising a plurality of cutting elements that form a cutter profile, wherein the at least one cutting element is oriented in the at least one cutter pocket such that the apex is aligned to be substantially perpendicular to the cutter profile. 
     
     
       36. The fixed cutter drill bit of claim 34, wherein the apex comprises a convex curvature. 
     
     
       37. A fixed cutter drill bit, comprising:
 a bit body having a bit axis and a direction of rotation about the bit axis;   at least one blade extending from the bit body, the at least one blade having a leading face facing the direction of rotation of the bit body about the bit axis, a trailing face facing away from the direction of rotation of the bit body about the bit axis, and a formation facing surface extending between the leading face and the trailing face, the at least one blade having at least one cutter pocket formed therein, the at least one cutter pocket opening to the leading face of the at least one blade; and   a plurality of cutting elements forming a cutting profile, at least one of the plurality of cutting elements being attached to the at least one cutter pocket and comprising:
 a base portion; and 
 an ultrahard layer on the base portion comprising an exposed top surface surrounded by a peripheral edge, the exposed top surface extending a height above the base portion to an apex that extends from a first region of the peripheral edge forming first cutting edge portion along the peripheral edge to another region of the peripheral edge and the exposed top surface decreasing in height in a direction away from the height of the apex and first cutting edge towards the base portion to another portion of the peripheral edge that has a lower overall height than the height of the cutting edge, 
   wherein the at least one of the plurality of cutting element is oriented in the at least one cutter pocket such that the apex is aligned to be substantially perpendicular to the cutter profile.   
     
     
       38. The fixed cutter drill bit of claim 37, wherein the apex comprises a flat region extending from the first cutting edge to the other portion of the peripheral edge. 
     
     
       39. The fixed cutter drill bit of claim 37, wherein the apex comprises a convex curvature.