Drill bit seal and method of using same

Abstract

A seal for a rolling cutter drill bit is provided. The seal has a ring shaped seal body having an inside diameter and an outside diameter, and a mud lobe and a grease lobe extending from the inside diameter of the seal body. The seal body has an asymmetrical, longitudinal cross-section such that, when positioned in a seal groove of the drill bit and compressed therein under downhole pressure, the mud lobe and grease lobe are maintained in contact with a seal land of the seal groove. The seal body may be provided with a garter spring and/or a textured pattern.

What is claimed is: 
     
         1 . A seal of a rolling cutter drill bit, the drill bit having a bearing spindle and a rolling cutter with a seal groove therebetween, the drill bit advanceable into the earth by a downhole tool, the seal comprising:
 a ring shaped seal body having an inside diameter and an outside diameter, a mud lobe and a grease lobe extending from the inside diameter of the seal body, the seal body having an asymmetrical longitudinal cross-section such that, when positioned in the seal groove of the drill bit and compressed therein under downhole pressure, the mud lobe and grease lobe are maintained in contact with a seal land of the seal groove.   
     
     
         2 . The seal of  claim 1 , wherein the seal body has a mud cavity extending into a mud side of the seal body and defining a mud area therein and a grease cavity extending into a grease side of the seal body and defining a grease area therein. 
     
     
         3 . The seal of  claim 2 , wherein the mud area is greater than the grease area. 
     
     
         4 . The seal of  claim 2 , wherein a seal ratio of the mud area to the grease area is greater than 2.5. 
     
     
         5 . The seal of  claim 4 , wherein the seal ratio is greater than 2.67. 
     
     
         6 . The seal of  claim 2 , wherein the mud cavity and the grease cavity are one of concave, polygonal or combinations thereof. 
     
     
         7 . The seal of  claim 1 , wherein the mud lobe has a pointed tip. 
     
     
         8 . The seal of  claim 1 , wherein a mud gap is provided between the mud lobe and a mud wall of the groove. 
     
     
         9 . The seal of  claim 1 , wherein a grease gap is provided between the grease lobe and a grease wall of the groove. 
     
     
         10 . The seal of  claim 1 , wherein the mud lobe and the grease lobe having a seal land gap therebetween. 
     
     
         11 . The seal of  claim 1 , wherein a mud ear and a grease ear extend from the outside diameter of the seal body. 
     
     
         12 . The seal of  claim 11 , wherein the mud ear and the grease ear having an air gap therebetween. 
     
     
         13 . The seal of  claim 12 , wherein, under the downhole pressure, the outside diameter of the seal body is pressed against a bottom of the seal groove such that the air gap is reduced. 
     
     
         14 . The seal of  claim 1 , wherein, under the downhole pressure, a grease side of the seal body is pressed against a grease wall of the seal groove. 
     
     
         15 . The seal of  claim 14 , wherein, under the downhole pressure, a grease gap between the grease lobe and the grease wall of the seal groove is reduced. 
     
     
         16 . The seal of  claim 1 , wherein the downhole pressure comprises hydrostatic pressure, high hydrostatic pressure of greater than 1,000 kg/cm, pressure from cuttings and combinations thereof. 
     
     
         17 . The seal of  claim 1 , further comprising a spring positionable in a spring cavity extending into the seal body. 
     
     
         18 . The seal of  claim 17 , wherein the spring is a garter spring. 
     
     
         19 . The seal of  claim 17 , wherein the spring cavity extends into a grease side of the seal body. 
     
     
         20 . The seal of  claim 17 , wherein the seal body has a mud cavity extending into a mud side of the seal body and defining a mud area therein and a grease cavity extending into a grease side of the seal body and defining a grease area therein. 
     
     
         21 . The seal of  claim 1 , wherein the seal body comprises one of elastomer, a rubber, fluorocarbon, perfluoroelastomer, tetrafluoroethylene propylene, and combinations thereof. 
     
     
         22 . The seal of  claim 1 , further comprising a textured surface on the inside diameter thereof, the textured surface having a plurality of textured ribs and a plurality of mud side lips. 
     
     
         23 . A rolling cutter earth boring drill bit advanceable into the earth by a downhole tool, the drill bit comprising:
 at least one leg;   a bearing spindle at a cutter end of the at least one leg;   a rolling cutter positionable about the bearing spindle with a seal groove therebetween; and   a seal positionable in the seal groove, the seal comprising a ring shaped seal body having an inside diameter and an outside diameter, a mud lobe and a grease lobe extending from the inside diameter of the seal body, the seal body having an asymmetrical longitudinal cross-section such that, when positioned in the seal groove of the drill bit and compressed therein under downhole pressure, the mud lobe and grease lobe are maintained in contact with a seal land of the seal groove.   
     
     
         24 . The drill bit of  claim 23 , further comprising at least one cutting insert. 
     
     
         25 . The drill bit of  claim 23 , further comprising at least one bearing. 
     
     
         26 . The drill bit of  claim 25 , wherein the at least one bearing is one of ball, floating, bushing, cantilever and combinations thereof. 
     
     
         27 . The drill bit of  claim 23 , wherein the drill bit has an end connectable to the downhole tool. 
     
     
         28 . The drill bit of  claim 23 , wherein the seal further comprises a spring. 
     
     
         29 . A method of sealing a rolling cutter drill bit, the drill bit having a bearing spindle and a rolling cutter with a seal groove therebetween, the drill bit advanceable into the earth by a downhole tool, the method comprising:
 positioning a seal in the seal groove, the seal comprising a ring shaped seal body having an inside diameter and an outside diameter, a mud lobe and a grease lobe extending from the inside diameter of the seal body, the seal body having an asymmetrical longitudinal cross-section;   exposing the drill bit to downhole pressure; and   maintaining the mud lobe and grease lobe in contact with a seal land of the seal groove as the seal is compressed in the seal groove of the drill bit under the downhole pressure.   
     
     
         30 . The method of  claim 29 , wherein the downhole pressure comprises hydrostatic pressure, high hydrostatic pressure of greater than 1,000 kg/cm, pressure from cuttings and combinations thereof. 
     
     
         31 . A seal of a rolling cutter drill bit, the drill bit having a bearing spindle and a rolling cutter with a seal groove therebetween, the drill bit advanceable into the earth by a downhole tool, the seal comprising:
 a ring shaped seal body having an inside diameter and an outside diameter, the inside diameter having a textured surface thereon, the textured surface having central ridge with a mud side pattern and a grease side pattern, the mud side pattern having a plurality of ribs extending at an angle to a longitudinal axis of the seal body.   
     
     
         32 . The seal of  claim 31 , wherein the mud side pattern is different from the grease side pattern. 
     
     
         33 . The seal of  claim 31 , wherein the textured surface includes a side lip on a mud side of the mud side pattern. 
     
     
         34 . The seal of  claim 31 , wherein the plurality of ribs are at a 45 degree angle to the longitudinal axis of the seal body.