Drill bits having rotating cutting structures thereon

Abstract

A drill bit may include a bit body rotatable about a longitudinal axis and having, at one end, a connection for securing the drill bit to a drill string and having a face opposite the connection end; and a plurality of cutting structures having at least one fixed cutting structure disposed on the bit body face and at least one cutting body rotatably attached to the face of the bit body; wherein, in a rotated view of the plurality of cutting structures into a single plane, there is substantially no radial overlap between at least one fixed cutting structure and the at least one cutting body.

What is claimed: 
     
         1 . A drill bit, comprising:
 a bit body rotatable about a longitudinal axis and having, at one end, a connection for securing the drill bit to a drill string and having a face opposite the connection end; and   a plurality of cutting structures comprising:
 at least one fixed cutting structure disposed on the bit body face; and 
 at least one cutting body rotatably attached to the face of the bit body; 
   wherein, in a rotated view of the plurality of cutting structures into a single plane, there is substantially no radial overlap between at least one fixed cutting structure and the at least one cutting body.   
     
     
         2 . The drill bit of  claim 1 , wherein the at least one fixed cutting structure comprises at least one blade extending azimuthally from the bit body, the at least one blade having a plurality of cutters thereon. 
     
     
         3 . The drill bit of  claim 1 , wherein the at least one fixed cutting structure comprises a raised body extending from the face, the raised body having a plurality of blades extending azimuthally therefrom, the plurality of blades having a plurality of cutters thereon. 
     
     
         4 . The drill bit of  claim 1 , wherein the at least one fixed cutting structure comprises a cutting element inserted into an insert hole formed in the bit body. 
     
     
         5 . The drill bit of  claim 1 , wherein the plurality of cutting structures comprise a plurality of the cutting bodies, wherein each of the plurality of cutting bodies have a substantially parallel axis of rotation. 
     
     
         6 . The drill bit of  claim 1 , wherein the at least one cutting body comprises a plurality of raised segments azimuthally spaced about the at least one cutting body. 
     
     
         7 . The drill bit of  claim 1 , wherein the at least one cutting body comprises a plurality of cutting elements thereon. 
     
     
         8 . The drill bit of  claim 1 , wherein the cutting surface of the at least one fixed cutting structure has an axial overlap with the cutting surface of the at least one cutting body. 
     
     
         9 . The drill bit of  claim 1 , wherein the bottommost extent of the at least one cutting body is located axially above the bottommost extent of the at least one fixed cutting structure. 
     
     
         10 . The drill bit of  claim 1 , wherein the at least one cutting body comprises a shaft that extends into the bore formed in the face of the bit body. 
     
     
         11 . The drill bit of  claim 1 , wherein a turbine assembly is connected to the drill string. 
     
     
         12 . A drill bit, comprising:
 a bit body rotatable about a longitudinal axis and having, at one end, a connection for securing the drill bit to a drill string and having a face opposite the connection end; and   a plurality of cutting structures comprising:
 a plurality of cutting bodies rotatably attached to the face of the bit body, 
 wherein each of the plurality of cutting bodies have a substantially parallel axis of rotation and have axially overlapping cutting surfaces; and 
   wherein the bit body has no blades extending azimuthally therefrom.   
     
     
         13 . The drill bit of  claim 12 , further comprising:
 at least one leg extending from a face of the bit body and having a journal formed thereon; and   wherein the plurality of cutting structures further comprises at least one roller cone rotatably mounted on the journal.   
     
     
         14 . The drill bit of  claim 12 , wherein the plurality of cutting structures consist of the plurality of cutting bodies. 
     
     
         15 . The drill bit of  claim 12 , wherein the plurality of cutting structures further comprises a cutting element inserted into an insert hole formed in the bit body. 
     
     
         16 . The drill bit of  claim 12 , wherein the plurality of rotating cutting bodies comprises a cylindrical body. 
     
     
         17 . The drill bit of  claim 16 , wherein the cylindrical body comprises cutting elements disposed circumferentially around the cylindrical body. 
     
     
         18 . The drill bit of  claim 16 , wherein the cylindrical body comprises cutting elements disposed on the planar surface thereof. 
     
     
         19 . The drill bit of  claim 12 , wherein a turbine assembly is connected to the drill string. 
     
     
         20 . A drill bit, comprising:
 a bit body rotatable about a longitudinal axis and having, at one end, a connection for securing the drill bit to a drill string and having a face opposite the connection end; and   at least one cutting structure comprising:
 at least one cutting body rotatably attached to the face of the bit body, wherein the at least one cutting body comprises a plurality of raised segments aximuthally spaced about the at least one cutting body. 
   
     
     
         21 . The drill bit of  claim 20 , wherein the at least one cutting structure further comprises at least one blade extending azimuthally from the bit body, the at least one blade having a plurality of cutters thereon. 
     
     
         22 . The drill bit of  claim 21 , wherein, in a rotated view of the plurality of cutting structures into a single plane, there is radial overlap between the cutters at least one blade and the at least one cutting body. 
     
     
         23 . The drill bit of  claim 20 , wherein the at least one fixed cutting structure comprises a raised body extending from the face, the raised body having a plurality of blades extending azimuthally therefrom, the plurality of blades having a plurality of cutters thereon. 
     
     
         24 . The drill bit of  claim 20 , wherein the at least one fixed cutting structure comprises a cutting element inserted into an insert hole formed in the bit body. 
     
     
         25 . The drill bit of  claim 20 , wherein the plurality of cutting structures comprise a plurality of the cutting bodies, wherein each of the plurality of cutting bodies have a substantially parallel axis of rotation. 
     
     
         26 . A drill bit, comprising:
 a bit body rotatable about a longitudinal axis and having, at one end, a connection for securing the drill bit to a drill string and having a face opposite the connection end, wherein the face comprises at least one bore formed therein; and   at least one cutting structure comprising:
 at least one cutting body rotatably attached to the face of the bit body, wherein the at least one cutting body comprises an exposed end and a shaft that extends into the bore formed in the face of the bit body. 
   
     
     
         27 . The drill bit of  claim 26 , wherein the at least one cutting body has an opening formed on the surface thereof, the opening fluidly connected to a conduit extending through the exposed end and the shaft for channeling a fluid from a fluid plenum to outside the bit. 
     
     
         28 . The drill bit of  claim 26 , wherein the drill bit further comprises:
 a first seal gland formed between the shaft of the at least one cutting body and the bit body proximal the face of the bit body; and   a first seal disposed in the first seal gland.   
     
     
         29 . The drill bit of  claim 26 , wherein the drill bit further comprises:
 a second seal gland formed between the shaft of the at least one cutting body and the bit body proximal the end of the shaft; and   a second seal disposed in the second seal gland.   
     
     
         30 . The drill bit of  claim 26 , further comprising:
 a bearing sleeve disposed in a bearing sleeve housing formed between radial surfaces of the shaft and the bit body.   
     
     
         31 . The drill bit of  claim 26 , further comprising:
 a thrust bearing disposed in a thrust bearing housing formed between axial surface of the shaft and the bit body.   
     
     
         32 . The drill bit of  claim 26 , further comprising:
 a plurality of retention balls disposed in a ball race formed between the shaft and the bit body.   
     
     
         33 . The drill bit of  claim 26 , further comprising:
 a first seal gland formed between the shaft of the at least one cutting body and the bit body proximal the face of the bit body;   a first seal disposed in the first seal gland;   a bearing sleeve disposed in a bearing sleeve housing formed between radial bearing surfaces of the shaft and the bit body and axially adjacent the first seal gland;   a thrust bearing disposed in a thrust bearing housing formed between axial bearing surfaces of the shaft and the bit body and axially adjacent the bearing sleeve;   a lubricant reservoir in fluid connection with the bearing surfaces;   a plurality of retention balls disposed in a ball race formed between the shaft and the bit body and axially adjacent the thrust bearing;   a second seal gland formed between the shaft of the at least one cutting body and the bit body proximal the end of the shaft;   a second seal disposed in the second seal gland;   wherein the at least one cutting body has an opening formed on the surface thereof, the opening fluidly connected to a conduit extending through the exposed end and the shaft for channeling a fluid from a fluid plenum to outside the bit, and wherein the second seal seals the bearing surfaces from the fluid.   
     
     
         34 . The drill bit of  claim 26 , further comprising a mechanical seal assembly disposed between the cutting body and the bit body, proximal to the face of the bit body, wherein the mechanical seal assembly comprises:
 a first sealing ring proximate to the cutting body;   an elastomer energizer proximate to the bit body; and   a second sealing ring disposed between the first sealing ring and the elastomer energizer.   
     
     
         35 . The drill bit of  claim 34 , wherein the first sealing ring contacts the second sealing ring at an interface surface having a width of less than 0.4 inches. 
     
     
         36 . The drill bit of  claim 34 , wherein the elastomer energizer comprises a fluoroelastomer, perfluoroelastomer, highly saturated nitrile, or a combination thereof. 
     
     
         37 . The drill bit of  claim 34 , wherein the first sealing ring is integral with the cutting body. 
     
     
         38 . The drill bit of  claim 34 , wherein at least one of the first sealing ring and the second sealing ring has a diamond coating there between. 
     
     
         39 . The drill bit of  claim 34 , further comprising an o-ring disposed between the second sealing ring and the bit body, adjacent to the elastomer energizer. 
     
     
         40 . The drill bit of  claim 26 , further comprising an open bearing system, wherein the open bearing system comprises:
 a radial bearing surface extending around the circumference of the shaft;   a bearing sleeve disposed around the axial bearing surface;   a thrust bearing disposed between the shaft and the base of the bore, wherein the thrust bearing comprises at least two bearing rings.   
     
     
         41 . The drill bit of  claim 40 , wherein at least one of the radial bearing surface, the bearing sleeve and the thrust bearing comprises wear buttons. 
     
     
         42 . The drill bit of  claim 40 , wherein the bearing sleeve comprises at least one of tungsten carbide, silicon carbide and polycrystalline diamond. 
     
     
         43 . The drill bit of  claim 40 , wherein the thrust bearing comprises three bearing rings and wherein one of the bearing rings is a wear ring disposed between the other two bearing rings. 
     
     
         44 . The drill bit of  claim 40 , wherein wear buttons are disposed between two bearing rings of the thrust bearing. 
     
     
         45 . The drill bit of  claim 26 , wherein a turbine assembly is connected to the drill string.