Drill bit having an improved seal and lubrication method using same

Abstract

A drill bit ( 100 ) for drilling a wellbore that traverses subterranean formations includes a drill bit body ( 106 ) having a plurality of journal pins ( 112 ), each having a bearing surface ( 128 ), and a rotary cutter ( 104 ) rotatably mounted on each journal pin ( 112 ), each rotary cutter ( 104 ) including a bearing surface ( 126 ). A pressure-compensated reservoir ( 130 ) is in fluid communication with the bearing surfaces ( 126, 128 ) and has a lubricant therein. A seal element ( 144 ) is positioned between each journal pin ( 112 ) and rotary cutter ( 104 ) and retains the lubricant in the bearing surfaces ( 126, 128 ). The seal element ( 144 ) is formed from a nanocomposite material including a polymer host material and a plurality of nanostructures.

1. A drill bit for drilling a wellbore, the drill bit comprising:
 a drill bit body having at least one bearing;  
 a rotary cutter rotatably attached to the drill bit body at the bearing; and  
 a seal element positioned between the drill bit body and the rotary cutter, the seal element comprising a nanocomposite material including a polymer host material and a plurality of nanostructures selected from the group consisting of polysilane resins, polycarbosilane resins, polysilsesquioxane resins and , polyhedral oligomeric silsesquioxane resins, monomers, polymers and copolymers of any of these resins, and any of the preceding nanostructures further containing termination points.  
 
     
     
       2. The drill bit as recited in  claim 1  wherein the seal element is selected from the group consisting of o-ring seals, d-seals, t-seals, v-seals, flat seals and lip seals. 
     
     
       3. The drill bit as recited in  claim 1  wherein the polymer host material further comprises an elastomer. 
     
     
       4. The drill bit as recited in  claim 3  wherein the elastomer is selected from the group consisting of nitrile butadiene, carboxylated acrylonitrile butadiene, hydrogenated acrylonitrile butadiene, highly saturated nitrile, carboxylated hydrogenated acrylonitrile butadiene, ethylene propylene, ethylene propylene diene, tetrafluoroethylene and propylene, fluorocarbon and perfluoroelastomer. 
     
     
       5. The drill bit as recited in  claim 1  wherein the nanostructures further comprise nanoparticles having a scale in the range of approximately 0.1 nanometer to approximately 500 nanometers. 
     
     
       6. The drill bit as recited  claim 1  wherein the nanostructures further comprise a material selected from the group consisting of metal oxides, nanoclays and carbon nanostructures. 
     
     
       7. The drill as recited in  claim 1  wherein the nanostructures further comprise silicon. 
     
     
       8. The drill bit as recited in  claim 1  wherein the polymer host material and the nanostuctures have interfacial interactions selected from the group consisting of copolymerization, crystallization, van der Waals interactions and cross-linking interactions. 
     
     
       9. A drill bit for drilling a wellbore, the drill bit comprising;
 a drill bit body including a coupling that attaches to a drill string and a plurality of journal pins, each having a bearing surface;  
 a rotary cutter rotatably mounted on each journal pin, each rotary cutter including a bearing surface;  
 a pressure-compensated reservoir in fluid communication with the bearing surfaces having a lubricant therein; and  
 a seal element positioned between each journal pin and rotary cutter, the seal elements retaining the lubricant in the bearing surfaces, the seal elements comprising a nanocomposite material including a polymer host material and a plurality of nanostuctures selected from the group consisting of polysilane resins, polycarbosilane resins, polysilsesquioxane resins and , polyhedral oligomeric silsesquioxane resins, monomers, polymers and copolymers of any of these resins, and any of the preceding nanostructures that also contain termination points.  
 
     
     
       10. The drill bit as recited in  claim 9  further comprising a diaphragm positioned within the pressure-compensated reservoir, the diaphragm comprising a nanocomposite material including a polymer host material and a plurality of nanostuctures. 
     
     
       11. The drill bit as recited in  claim 9  wherein the seal element is selected from the group consisting of o-ring seals, d-seals, t-seals, v-seals, flat seals and lip seals. 
     
     
       12. The drill bit as recited in  claim 9  wherein the polymer host material further comprises an elastomer. 
     
     
       13. The drill bit as recited in  claim 12  wherein the elastomer is selected from the group consisting of nitrile butadiene, carboxylated acrylonitrile butadiene, hydrogenated acrylonitrile butadiene, highly saturated nitrile, carboxylated hydrogenated acrylonitrile butadiene, ethylene propylene, ethylene propylene diene, tetrafluoroethylene and propylene, fluorocarbon and perfluoroelastomer. 
     
     
       14. The drill bit as recited in  claim 9  wherein the nanostructures further comprise nanoparticles having a scale in the range of approximately 0.1 nanometer to approximately 500 nanometers. 
     
     
       15. The drill bit as recited in  claim 9  wherein the nanostructures further comprise a material selected from the group consisting of metal oxides, nanoclays and carbon nanostuctures. 
     
     
       16. The drill bit is recited in  claim 9  wherein the nanostructures further comprise silicon. 
     
     
       17. The drill bit as recited in  claim 9  wherein the polymer host material and the nanostructures have interfacial interactions selected from the group consisting of copolymerization, crystallization, van der Waals interactions and cross-linking interactions. 
     
     
       18. The drill bit as recited in  claim 9  wherein the nanostructures further comprise carbon. 
     
     
       19. A drill bit for drilling a wellbore, the drill bit comprising:
 a drill bit body including a coupling that attaches to a drill string and a plurality of journal pins, each having a bearing surface;  
 a rotary cutter rotatably mounted on each journal pin, each rotary cutter including a bearing surface;  
 a pressure-compensated reservoir in fluid communication with the bearing surfaces having a lubricant therein;  
 a diaphragm positioned within the pressure-compensated reservoir, the diaphragm comprising a nanocomposite material including a polymer host material and a plurality of nanostructures selected from the group consisting of polysilane resins, polycarbosilane resins, polysilsesquioxane resins and , polyhedral oligomeric silsesquioxane resins, monomers, polymers and copolymers of any of these resins, and any of the preceding nanostructures that also contain termination points; and  
 a seal element positioned between each journal pin and rotary cutter, the seal elements retaining the lubricant in the bearing surfaces.  
 
     
     
       20. The drill bit as recited in  claim 19  wherein the seal element comprising a nanocomposite material including a polymer host material and a plurality of nanostructures. 
     
     
       21. The drill bit as recited in  claim 20  wherein the seal element is selected from the group consisting of o-ring seals, d-seals, t-seals, v-seals, flat seals and lip seals. 
     
     
       22. The drill bit as recited in  claim 19  wherein the polymer host material further comprises an elastomer. 
     
     
       23. The drill bit as recited in  claim 22  wherein the elastomer is selected from the group consisting of nitrile butadiene, carboxylated acrylonitrile butadiene, hydrogenated acrylonitrile butadiene, highly saturated nitrile, carboxylated hydrogenated acrylonitrile butadiene, ethylene propylene, ethylene propylene diene, tetrafluoroethylene and propylene, fluorocarbon and perfluoroelastomer. 
     
     
       24. The drill bit as recited in  claim 19  wherein the nanostructures further comprise nanoparticles having a scale in the range of approximately 0.1 nanometer to approximately 500 nanometers. 
     
     
       25. The drill bit as recited in  claim 19  wherein the nanostructures further comprise a material selected from the group consisting of metal oxides, nanoclays and carbon nanostructures. 
     
     
       26. The drill bit as recited in  claim 19  wherein the nanostructures further comprise silicon. 
     
     
       27. The drill bit as recited in  claim 19  wherein the polymer host material and the nanostructures have interfacial interactions selected from the group consisting of copolymerization, crystallization, van der Waals interactions and cross-linking interactions. 
     
     
       28. A method for lubricating a drill bit for drilling a wellbore, the drill bit including a drill bit body having at least one bearing and a rotary cutter rotatably attached to the drill bit body at the bearing, the method comprising the steps of:
 introducing a lubricant into a pressure-compensated reservoir in fluid communication with the bearing; and  
 retaining the lubricant within the drill bit with a seal element comprising a nanocomposite material including a polymer host material and a plurality of nanostructures selected from the group consisting of polysilane resins, polycarbosilane resins, polysilsesquioxane resins and , polyhedral oligomeric silsesquioxane resins, monomers, polymers and copolymers of any of these resins, and any of the preceding nanostructures that also contain termination points.  
 
     
     
       29. The method as recited in  claim 28  further comprising the step of applying pressure from the exterior of the drill bit on the lubricant with a diaphragm comprising a nanocomposite material including a polymer host material and a plurality of nanostructures. 
     
     
       30. The method as recited in  claim 28  wherein the step of retaining the lubricant within the drill bit with a seal element further comprises retaining the lubricant within the drill bit with a seal element selected from the group consisting of o-ring seals, d-seals, t-seals, v-seals, flat seals and lip seals. 
     
     
       31. The method as recited in  claim 28  wherein the step of retaining the lubricant within the drill bit with a seal element further comprises selecting the polymer host material from the group consisting of elastomers. 
     
     
       32. The method as recited in  claim 28  wherein the step of retaining the lubricant within the drill bit with a seal element further comprises selecting the polymer host material from the group consisting of nitrile butadiene, carboxylated acrylonitrile butadiene, hydrogenated acrylonitrile butadiene, highly saturated nitrile, carboxylated hydrogenated acrylonitrile butadiene, ethylene propylene, ethylene propylene diene, tetrafluoroethylene and propylene, fluorocarbon and perfluoroelastomer. 
     
     
       33. The method as recited in  claim 28  wherein the step of retaining the lubricant within the drill bit with a seal element further comprises selecting the nanostructures from nanomaterials having a scale in the range of approximately 0.1 nanometer to approximately 500 nanometers. 
     
     
       34. The method as recited in  claim 28  wherein the step of retaining the lubricant within the drill bit with a seal element further comprises selecting the nanostructures from the group consisting of metal oxides, nanoclays and carbon nanostructures. 
     
     
       35. The method as recited in  claim 28  wherein the step of retaining the lubricant within the drill bit with a seal element further comprises selecting the nanostructures from the group consisting of silicon based nanomaterials.