Patent Publication Number: US-10774593-B2

Title: Sealing elements for roller cone bits

Description:
BACKGROUND 
     Several types of drill bits can be used to drill a wellbore for hydrocarbon extraction or for any other purpose. One type of drill bit is a roller cone bit, alternately referred to as a rotary cone bit or a rock bit. Briefly, roller cone bits commonly include a plurality of cutter cone assemblies (typically three) rotatably coupled to a bit body. As the bit body is rotated about its central axis, the cutter cone assemblies cooperatively grind and crush underlying rock to form a wellbore. 
     Roller cone bits also typically include an internal lubrication system that uses a fairly viscous lubricant. The lubricant is retained within the lubrication system using one or more sealing elements strategically positioned in each cutter cone assembly. The sealing elements prevent the migration of fluids and/or debris into the interior portions of the cutter cone assemblies, which could otherwise contaminate vital bearing surfaces and thereby reduce the operational lifespan of the roller cone bit. 
     Such sealing elements can wear rather rapidly because of the harsh and abrasive environments in which roller cone bits commonly operate. For instance, during operation the sealing elements are commonly subjected to drilling fluids, which can contain fine abrasive particulates, such as bentonite and drill cuttings. The sealing elements are also commonly subjected to high temperatures, large pressure fluctuations, and dynamic movement between the cutter cone assemblies and the bit body. A good sealing element design must have the ability to continue to perform its sealing function under these harsh and abrasive environments with a low leakage rate, and the design must also preferably offer an extended service life. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following figures are included to illustrate certain aspects of the present disclosure, and should not be viewed as exclusive embodiments. The subject matter disclosed is capable of considerable modifications, alterations, combinations, and equivalents in form and function, without departing from the scope of this disclosure. 
         FIG. 1  is an example drilling system that may employ the principles of the present disclosure. 
         FIGS. 2A and 2B  are views of an example roller cone drill bit that may incorporate the principles of the present disclosure. 
         FIG. 2C  is another embodiment of the cutter cone assembly of  FIG. 2B . 
         FIG. 3  is an enlarged cross-sectional side view of a portion of the drill bit of  FIG. 2B  showing an example embodiment of a sealing element. 
         FIGS. 4A-4E  are various views of the sealing element of  FIGS. 2B and 3 . 
         FIGS. 5A and 5B  are views of another embodiment of the sealing element of  FIGS. 2B and 3 , according to one or more embodiments. 
         FIG. 6  is an isometric view of another embodiment of the sealing element of  FIGS. 2B and 3 . 
         FIGS. 7A-7J  are cross-sectional end views of example sealing elements that may be used in accordance with the present disclosure. 
         FIGS. 8A and 8B  are enlarged views of a portion of the dynamic surface of additional example sealing elements. 
         FIGS. 9A-9C  are cross-sectional end views of additional example sealing elements that may be used in accordance with the present disclosure. 
         FIG. 10  is an enlarged cross-sectional side view of a portion of the drill bit of  FIG. 2B  showing another example embodiment of a sealing element. 
         FIGS. 11A-11E  are various views of the sealing element of  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION 
     This present disclosure is related to roller cone drill bits and, more particularly, to sealing elements that are ported to provide lubrication to a dynamic seal surface during operation. The embodiments discussed herein describe a sealing element used to seal between a stationary first member and a dynamic (rotating) second member. The first member, for instance, can be a journal in a cutter cone assembly, and the second member can be a roller cone rotatably mounted to the journal. A seal groove is defined at least partially between the first and second members and the sealing element is positioned in the seal groove. The sealing element provides an annular body that has a first axial surface, a second axial surface opposite the first axial surface, an inner radial surface, and an outer radial surface opposite the inner radial surface. In some embodiments, the second axial side comprises a lubricant surface and the inner radial surface comprises a dynamic surface that seals against the first member as the sealing element rotates with the second member. In other embodiments, however, the inner radial surface comprises the lubricant surface and the first axial side comprises the dynamic surface. An inlet aperture may be defined on the lubricant surface, an outlet aperture may be defined on the dynamic surface, and a lubricant channel is defined through the sealing element and extends between the inlet and outlet apertures to provide a lubricant to the dynamic surface. The lubricant channel may be in fluid communication with a lubricant chamber and is, therefore, able to maintain constant lubrication of the dynamic surface, which may improve the operational lifespan of the sealing element. 
       FIG. 1  is an example drilling system  100  that may employ one or more principles of the present disclosure. Boreholes may be created by drilling into the earth  102  using the drilling system  100 . The drilling system  100  may include and drive a bottom hole assembly (BHA)  104  positioned or otherwise arranged at the bottom of a drill string  106  extended into the earth  102  from a derrick  108  arranged at the surface  110 . The derrick  108  includes a kelly  112  and a traveling block  113  used to lower and raise the kelly  112  and the drill string  106 . 
     The BHA  104  includes a drill bit  114  operatively coupled to a tool string  116 , which is moved axially within a drilled wellbore  118  as attached to the drill string  106 . The drill bit  114  used to form the wellbore  118  can take on several designs or configurations. One example of the drill bit  114  is a roller cone bit, also commonly referred to as a rotary cone or rock bit. During operation, the drill bit  114  penetrates the earth  102  and thereby creates the wellbore  118 . The BHA  104  provides directional control of the drill bit  114  as it advances into the earth  102 . The tool string  116  can be semi-permanently mounted with various measurement tools (not shown) such as, but not limited to, measurement-while-drilling (MWD) and logging-while-drilling (LWD) tools, that may be configured to take downhole measurements of drilling conditions. 
     Drilling fluid or “mud” from a mud tank  120  may be pumped downhole using a mud pump  122  powered by an adjacent power source, such as a prime mover or motor  124 . The drilling fluid may be pumped from the mud tank  120 , through a standpipe  126 , which feeds the drilling fluid into the drill string  106  and conveys the same to the drill bit  114 . The drilling fluid exits one or more nozzles arranged in the drill bit  114  and in the process cools the drill bit  114 . After exiting the drill bit  114 , the drilling fluid circulates back to the surface  110  via the annulus defined between the wellbore  118  and the drill string  106 , and in the process returns drill cuttings and debris to the surface. The cuttings and drilling fluid mixture are passed through a flow line  128  and are processed such that a cleaned drilling fluid is returned down hole through the standpipe  126  once again. 
     Although the drilling system  100  is shown and described with respect to a rotary drill system in  FIG. 1 , those skilled in the art will readily appreciate that many types of drilling systems can be employed in carrying out embodiments of the disclosure. For instance, drills and drill rigs used in embodiments of the disclosure may be used onshore (as depicted in  FIG. 1 ) or offshore (not shown). Offshore oilrigs that may be used in accordance with embodiments of the disclosure include, for example, floaters, fixed platforms, gravity-based structures, drill ships, semi-submersible platforms, jack-up drilling rigs, tension-leg platforms, and the like. It will be appreciated that embodiments of the disclosure can be applied to rigs ranging anywhere from small in size and portable, to bulky and permanent. 
     Further, although described herein with respect to oil drilling, various embodiments of the disclosure may be used in many other applications. For example, disclosed methods can be used in drilling for mineral exploration, environmental investigation, natural gas extraction, underground installation, mining operations, water wells, geothermal wells, and the like. Further, embodiments of the disclosure may be used in weight-on-packers assemblies, in running liner hangers, in running completion strings, casing drilling strings, liner drilling strings, pipe in pipe drilling systems, coil tubing drilling systems, etc., without departing from the scope of the disclosure. 
       FIG. 2A  is a plan view of an example roller cone drill bit  200  that may incorporate the principles of the present disclosure. The drill bit  200  may be the same as or similar to the drill bit  114  of  FIG. 1  and, therefore, may be used to drill the wellbore  118 . As illustrated, the drill bit  200  may include a threaded pin connection  202  used to attach the drill bit  200  to a drill string  204  and, more particularly, to the BHA  104  ( FIG. 1 ). The pin connection  202  and the corresponding threaded connections of the drill string  204  are designed to allow rotation of the drill bit  200  in response to rotation of the drill string  204 . 
     As the drill bit  200  operates, an annulus  206  is formed between the exterior of the drill string  204  and an inner wall  208  of the wellbore  118 . In addition to rotating the drill bit  200 , the drill string  204  may also be used as a conduit for communicating drilling fluid (“mud”) from the well surface to the drill bit  200  at the bottom of the wellbore  118 . The drilling fluid may be ejected out of the drill bit  200  via various nozzles  210  provided in the drill bit  200 . Cuttings generated by the drill bit  200  and other debris at the bottom of the wellbore  118  will mix with the drilling fluid exiting the nozzles  210  and return to the well surface via the annulus  206 . 
     Cutting, grinding, and/or drilling action of the drill bit  200  occurs as one or more cutter cone assemblies  212  are rolled around the bottom of the wellbore  118  by rotation of the drill string  204 . The cutter cone assemblies  212  cooperate with each other to form the wellbore  118  in response to rotation of the drill bit  200 . Each cutter cone assembly  212  may include cutting edges  214  with protruding inserts  216  configured to scrape and gouge the sides and bottom of the wellbore  118  in response to the weight and rotation applied to the drill bit  200  from the drill string  204 . 
     The drill bit  200  may include a one-piece or unitary bit body  218  and one or more support arms  220  (typically three) angularly spaced from each other about the periphery of the bit body  218 . 
       FIG. 2B  is a partial cross-sectional side view of one of the cutter cone assemblies  212  mounted to a corresponding support arm  220 . Each support arm  220  includes a journal  222  that extends from the respective support arm  220 . Each cutter cone assembly  212  is configured to be mounted on its associated journal  222  in a substantially identical manner. Accordingly, only one support arm  220  and cutter cone assembly  212  are described herein since the same description applies generally to the other support arms  220  and their associated cutter cone assemblies  212 . 
     The cutter cone assembly  212  includes a roller cone  226  that, as illustrated, may exhibit a generally frustoconical shape. The roller cone  226  defines an internal cavity configured to receive the journal  222  to mount the roller cone  226  on the journal  222 . The journal  222  may be angled downwardly and inwardly with respect to the projected axis of rotation of the drill bit  200 . This orientation of the journal  222  results in the roller cone  226  and the associated cutting edges  214  and inserts  216  engaging the side and bottom of the wellbore  118  during drilling operations. 
     A lubricant passage  228  is defined in the support arm  220  and is in communication with a lubricant supply  230 . The journal  222  may include a plurality of bearing systems and assemblies that support the roller cone  226  and maintain it against separation from the journal  222 . For example, the journal  222  may define a bearing insert bore  232  in fluid communication with the lubricant passage  228 . Ball bearings  234  may be inserted through the bearing insert bore  232  and into engagement with an outer bearing race  236   b  defined on the inner wall of the roller cone  226 . Thereafter, a ball plug  238  may be extended into the bearing insert bore  232  to engage an inner bearing race  236   a  against the ball bearings  234 . The ball plug  236  may be secured in immovable relation to the journal  222  by means of a weld connection  240 , for example. The ball bearings  234  provide rotatable bearing support of the roller cone  226  relative to the journal  222 . 
     The ball plug  238  may define a lubricant depression or groove  242  configured to convey lubricant to the ball bearings  234  from the lubricant passage  228 . The groove  242  may also fluidly communicate with a lubricant branch passage  244  defined in the journal  222 . The lubricant branch passage  244  may help convey lubricant to a bearing interface defined between opposing hardened cylindrical surfaces  246  of the roller cone  226  and the journal  222 , respectively, thus providing a film of lubricant between these relative movable surfaces. 
     The lubricant branch passage  244  may also help convey lubricant to a sealing element  250  positioned within a seal groove  252  and interposing the roller cone  226  and the journal  222 . In some embodiments, the seal groove  252  may be defined in the roller cone  226 , but may alternatively be formed in the journal  222 . In other embodiments, as illustrated, the journal  222  and the roller cone  226  may jointly define portions of the seal groove  252 . The sealing element  250  may be configured to prevent the migration of fluids and/or debris into the interior of the roller cone  226 , which could otherwise contaminate the bearing surfaces of the cutter cone assembly  212 . 
     In accordance with the present disclosure, and as is described below, the sealing element  250  may include one or more lubricant channels that convey lubrication or “grease” originating from the lubricant supply  230  to a dynamic surface of the sealing element  250 . As used herein, the term “dynamic surface” refers to a surface of the sealing element  250  that seals against an opposing stationary surface of the seal groove  252  as the sealing element  250  rotates, or otherwise refers to a surface of the sealing element  250  that seals against an opposing dynamic (i.e., displacing or rotating) surface of the seal groove  252  as the opposing dynamic surface rotates. As described herein, the dynamic surface of the sealing element  250  maintains constant lubrication of the opposing stationary or dynamic surface and thereby improves the life of the sealing element  250 . 
     The drill bit  200  and its foregoing description are merely provided for illustrative purposes in explaining the principles of the present disclosure. Those skilled in the art will readily recognize that other types and designs of roller cone drill bits and numerous structural variations and different configurations of the drill bit  200  may be employed, without departing from the scope of the disclosure. Accordingly, the foregoing description of the drill bit  200  should not be considered limiting to the scope of the present disclosure. 
       FIG. 2C , for example, is a partial cross-sectional side view of another type of cutter cone assembly  212  mounted to the journal  222  and able to utilize the principles of the present disclosure. In contrast the cutter cone assembly  212  of  FIG. 2B , the cutter cone assembly  212  of  FIG. 2C  includes one or more sets of roller bearings  254  used to help facilitate rolling engagement between the roller cone  226  and the journal  222 . While only two sets of roller bearings  254  are shown in  FIG. 2C , it will be appreciated that more (or less) than two sets may be employed, without departing from the scope of the disclosure. The lubricant passage  228  may be in fluid communication with the roller bearings  254  via the bearing insert bore  232  and the lubricant branch passage  244  to help convey lubricant to the roller bearings  254 . 
       FIG. 3  is an enlarged cross-sectional side view of a portion of the drill bit  200  showing an example embodiment of the sealing element  250  positioned within the seal groove  252 . In the illustrated embodiment, the seal groove  252  is cooperatively defined by the journal  222  and the roller cone  226 . More specifically, the journal  222  provides a first journal surface  302   a  and a second journal surface  302   b , where the second journal surface  302   b  extends generally perpendicular to the first journal surface  302   a  but may alternatively extend at any angle therefrom. In some embodiments, as illustrated, the seal groove  252  may define a radiused journal surface  304  that provides a transition between the first and second journal surfaces  302   a,b . Furthermore, the roller cone  226  provides a first cone surface  306   a  and a second cone surface  306   b , where the second cone surface  306   b  extends generally perpendicular to the first cone surface  306   a  but may alternatively extend at any angle therefrom. Accordingly, the first and second journal surfaces  302   a,b  and the first and second cone surfaces  306   a,b  may cooperatively define the seal groove  252 . 
     A small gap  308  is defined between the journal  222  and the roller cone  226  and allows the roller cone  226  to rotate relative to the journal  222  during operation. A lubricant  310  (alternately referred to as “grease”) is pumped into the gap  308  to lubricate the interface between the journal  222  and the roller cone  226 . The lubricant  310  may originate from the lubricant supply  230  ( FIG. 2B ) and may be fed into the gap  308  via the lubricant passage  228  ( FIG. 2B ) and the lubricant branch passage  244  ( FIG. 2B ). The gap  308  may also facilitate a conduit or pathway for the lubricant  310  to infiltrate and otherwise enter the seal groove  252  and thereby provide lubrication for the dynamic sealing engagement provided by the sealing element  250 . 
     The sealing element  250  generally comprises an annular (i.e., ring-shaped) structure having opposing axial ends in the form of a first axial surface  312   a  and a second axial surface  312   b  opposite the first axial surface  312   a . The first and second axial surfaces  312   a,b  generally refer to the axial ends or sides of the sealing element  250 . During operation, the first axial surface  312   a  will be exposed to debris and contaminant-laden fluids via an external separation  314  between the journal  222  and the roller cone  226 . Accordingly, the first axial surface  312   a  is often referred to and otherwise characterized as a “mud surface.” In contrast, the second axial surface  312   b  will be exposed to the lubricant  310  entering the seal groove  252  via the gap  308 . Accordingly, the second axial surface  312   b  is often referred to and otherwise characterized as a “lubricant surface.” In at least one embodiment, however, more than one sealing element may be arranged within the seal groove  252 . In such embodiments, the first axial surface  312   a  may not necessarily be exposed to debris and contaminant-laden fluids, but may instead be arranged axially adjacent another sealing element. 
     The sealing element  250  also includes opposing inner and outer diameters in the form of an inner radial surface  316   a  and an outer radial surface  316   b . The sealing element  250  of  FIG. 3  is configured as a radial seal where the inner and outer radial surfaces  316   a,b  provide sealed interfaces during operation. More specifically, the inner radial surface  316   a  is configured to sealingly engage the first journal surface  302   a , while the outer radial surface  316   b  is configured to sealingly engage the first cone surface  306   a . The sealing element  250  is maintained under sufficient compression to thereby ensure maintenance of a seal at the interface between the inner radial surface  316   a  and the first journal surface  302   a  and the interface between the outer radial surface  316   b  and the first cone surface  306   a.    
     In embodiments where the sealing element  250  rotates with the roller cone  226  relative to the journal  222 , the inner radial surface  316   a  will be characterized as the “dynamic surface.” In contrast, in embodiments where the sealing element  250  remains stationary with the journal  222  relative to the roller cone  226 , the outer radial surface  316   b  will be characterized as the “dynamic surface.” For purposes of the following description, however, it will be assumed that the sealing element  250  rotates with the roller cone  226  relative to the journal  222  and, therefore, the inner radial surface  316   a  will be referred to herein as the “dynamic surface  316   a .” It will be appreciated, however, that the principles of the present disclosure are equally applicable to embodiments where the outer radial surface  316   b  serves as the dynamic surface, without departing from the scope of the disclosure. 
     The sealing element  250  may be made of a variety of pliable or flexible materials including, but not limited to, elastomers, thermoplastics, and thermosets. Suitable elastomers that may be used for the sealing element  250  include, for example, nitrile butadiene (NBR) which is a copolymer of acrylonitrile and butadiene, carboxylated acrylonitrile butadiene (XNBR), butyl rubber, nitrile rubber, hydrogenated acrylonitrile butadiene (HNBR) which is commonly referred to as highly saturated nitrile (HSN), carboxylated hydrogenated acrylonitrile butadiene (XHNBR), hydrogenated carboxylated acrylonitrile butadiene (HXNBR), halogenated butyl rubbers, styrene-butadiene rubber, ethylene propylene rubber, ethylene propylene diene rubber, epichlorohydrin rubber, polyacrylic rubber, silicone rubber, fluorosilicone rubber, chloroprene rubber, polysulfide rubber, ethylene propylene (EPR), ethylene propylene diene (EPDM), tetrafluoroethylene and propylene (FEPM), fluorocarbon (FKM), perfluoroelastomer (FEKM), natural polyisoprene, synthetic polyisoprene, polybutadiene, polychloroprene, neoprene, baypren, fluoroelastomers, perfluoroelastomers, polyether block amides, chlorosulfonated polyethylene, ethylene-vinyl acetate, thermoplastic elastomers, resilin, elastin, combinations thereof, and the like. 
     Suitable thermoplastics that may be used for the sealing element  250  include, for example, polyphenylene sulfide (PPS), polyetheretherketones (e.g., PEEK, PEK and PEKK), and polytetrafluoroethylene (PTFE). Suitable thermosets that may be used for the sealing element  250  include, for example, epoxies and phenolics. 
     In some embodiments, the sealing element  250  may be made of a composite material including a nonelastomeric component bonded to a rubber matrix. One example nonelastomeric component is in the form of fibers such as those selected from the group consisting of polyester fiber, cotton fiber, stainless steel fibers aromatic polyamines (Aramids) such as those available under the Kevlar family of compounds, polybenzimidazole (PBI) fiber, poly m-phenylene isophthalamide fiber such as those available under the Nomex family of compounds, and mixtures or blends thereof such as PBI/Kevlar/stainless steel staple fabric. The fibers either can be used in their independent state and/or combined with an elastomeric composite component, or may be combined into threads or woven into fabrics with or without an elastomeric composite component. Other composite materials suitable for use in forming the sealing element  250  include those that display properties of high-temperature stability and endurance, wear resistance, and have a coefficient of friction similar to that of the polymeric material specifically mentioned above. If desired, glass fiber can be used to strengthen the polymeric fiber, in such case constituting the core for the polymeric fiber. 
     In some embodiments, as illustrated, the second axial surface  312   b  may be spaced from the second cone surface  306   b  and thereby define a lubricant chamber  318  within the seal groove  252 . During operation, the lubricant  310  may be pumped or otherwise migrate into and fill the lubricant chamber  318 . The lubricant  310  may be used to lubricate the interface between the dynamic surface  316   a  and the first journal surface  302   a , and thereby prolong the life of the sealing element  250 . 
     According to embodiments of the present disclosure, the sealing element  250  may provide and otherwise define a lubricant channel  320  that extends between the second axial surface  312   b  and the dynamic surface  316   a . The lubricant channel  320  may be machined into the sealing element  250  or may alternatively be molded into the sealing element  250  during manufacture. The lubricant channel  320  may provide a fluid passageway or conduit configured to convey the lubricant  310  from the lubricant chamber  318  directly to the interface between the dynamic surface  316   a  and the first journal surface  302   a  and at an axial location between the first axial surface  312   a  and the second axial surface  312   b.    
     In the illustrated embodiment, an axial channel  322   a  and a radial channel  322   b  jointly define the lubricant channel  320 . The axial channel  322   a  extends from the second axial surface  312   b  and the radial channel  322   b  extends from the dynamic surface  316   a  and is substantially perpendicular to the axial channel  322   a . The axial and radial channels  322   a,b  intersect at a location within the interior of the sealing element  250  to facilitate fluid communication from the lubricant chamber  318  to the dynamic surface  316   a . As will be appreciated, several variations and designs of the sealing element  250  and the lubricant channel  320  may be employed without departing from the scope of the disclosure. The following figures and discussion provide various contemplated designs and configurations for the sealing element  250  and the lubricant channel  320 , but should not be considered as limiting the scope of the disclosure. Rather, those skilled in the art will readily recognize that other designs and configurations could equally be used in keeping with the principles described herein. 
       FIGS. 4A-4E  are various views of the sealing element  250  of  FIGS. 2B and 3 , according to one or more embodiments. As illustrated in  FIG. 4A , the sealing element  250  may comprise an annular body  400  that defines and otherwise provides the opposing first and second axial surfaces  312   a,b , the dynamic surface  316   a , and the outer radial surface  316   b . The annular body  400  also provides a central axis  402 . 
     One or more inlet apertures  404  (four shown in  FIG. 4A ) may be defined in the second axial surface  312   b  and one or more outlet apertures  406  (two shown in  FIG. 4A ) may be defined in the dynamic surface  316   a . Each inlet and outlet aperture  404 ,  406  provides access into a corresponding channel  320  ( FIGS. 4B, 4C, and 4E ) extending between the second axial surface  312   b  and the dynamic surface  316   a.    
       FIG. 4B  is a partial cross-sectional view of the sealing element  250  as taken through angularly opposite channels  320 , and  FIG. 4C  is an enlarged cross-sectional view of the sealing element  250  as taken through one of the channels  320 . Each lubricant channel  320  includes the axial channel  322   a  extending from the second axial surface  312   b  and the radial channel  322   b  extending from the dynamic surface  316   a  and intersecting at a location within the interior of the sealing element  250  to facilitate fluid communication from the lubricant chamber  318  ( FIG. 3 ) to the dynamic surface  316   a . In some embodiments, the axial channel  322   a  may extend from the dynamic surface  316   a  at an angle substantially parallel to the central axis  402  ( FIG. 4A ), and the radial channel  322   b  may extend substantially perpendicular to the axial channel  322   a  and the central axis  402 . It will be appreciated, however, that the axial and radial channels  322   a,b  may alternatively extend at various other angles and nonetheless provide fluid communication between the second axial surface  312   b  and the dynamic surface  316   a , without departing from the scope of the disclosure. 
       FIG. 4D  is an enlarged view of a portion of the dynamic surface  316   a . In some embodiments, the outlet aperture  406  defined in the dynamic surface  316   a  may be offset from an annular centerline  408  of the sealing element  250 . The annular centerline  408  is the axial midpoint of the contact area of the sealing element  250  between the first and second axial surfaces  312   a,b . In the illustrated embodiment, the outlet aperture  406  is defined in the dynamic surface  316   a  at a location that is axially offset from the annular centerline  408  and axially closer to the second axial surface  312   b . In other embodiments, however, the outlet aperture  406  may be defined in the dynamic surface  316   a  at a location that is axially offset from the annular centerline  408  and axially closer to the first axial surface  312   a , or aligned with the annular centerline  408 , without departing from the scope of the disclosure. 
     Having the outlet aperture  406  located axially closer to the second axial surface  312   b , as compared to being closer to the first axial surface  312   a , may prove advantageous in prolonging the operational lifespan of the sealing element  250 . More specifically, a slurry of abrasive particulates commonly forms at the first axial surface  312   a  during operation, and will progressively erode away at the annular body  400  ( FIGS. 4A-4B ) on the first axial surface  312   a  as the sealing element  250  rotates (or as an opposing surface/substrate rotates). Eventually the axial thickness of the annular body  400  will erode away enough to reach the outlet aperture  406 , which could adversely affect the sealing performance of the sealing element  250 . Placing the outlet aperture  406  closer to the second axial surface  312   b , however, provides the sealing element  250  with a longer operational lifespan until the erosion reaches the outlet aperture  406 . Assuming the distance between the first and second axial surfaces  312   a,b  can be characterized as a percentage of axial distance between the two, the first axial surface  312   a  may be located at 100% of the axial distance and the second axial surface  312   b  may be located at 0%. In such a measurement scenario, the outlet aperture  406  may be located at a distance between about 49% and 10% of the axial distance between the first and second axial surfaces  312   a,b.    
     In some embodiments, each lubricant channel  320  may also include a slot  410  defined in the dynamic surface  316   a  and contiguous with the outlet aperture  406 . Each slot  410  may generally comprise a recess formed on the dynamic surface  316   a  that connects the outlet aperture  406  to the dynamic surface  316   a . The slot  410  may exhibit a length L and a width W, where the length L extends generally along the arcuate length of the dynamic surface  316   a  and the width W extends generally in the axial direction between the opposing first and second axial surfaces  312   a,b . The length L is typically greater than the width W, but in alternative embodiments, the width W may be greater than the length L, without departing from the scope of the disclosure. 
     In some embodiments, as illustrated, the slot  410  may include a first furrow  412   a  extending from the outlet aperture  406  in a first direction and a second furrow  412   b  extending from the outlet aperture  406  in a second direction opposite the first direction. In other embodiments, however, only one furrow  412   a,b  may be included. 
       FIG. 4E  is a cross-sectional side view of the sealing element  250  as taken along the lines  4 E- 4 E in  FIG. 4D . The depth of each furrow  412   a,b  may vary as extending from the outlet aperture  406  in each direction and otherwise along the arcuate length of the dynamic surface  316   a . In the illustrated embodiment, for example, each furrow  412   a,b  tapers radially inward and toward the dynamic surface  316   a  as extending in each corresponding direction away from the outlet aperture  406 . Consequently, the depth of the furrows  412   a,b  may be deepest near the outlet aperture  406  and tapers to zero or flush with the dynamic surface  316   a  at the ends of the length L ( FIG. 4D ). The furrows  412   a,b  may taper at an angle or alternatively over a curved or arcuate surface. In some embodiments, the taper of the furrows  412   a,b  may undulate. 
     The slots  410  may prove advantageous for inducing hydroplaning during operation of the sealing element  250 . More particularly, the lubricant  310  ( FIGS. 2B and 3 ) exits the outlet aperture  406  and is fed into the furrows  412   a,b  during operation. The lubricant  310  is continuously expressed (discharged) onto the opposing stationary or dynamic surface (e.g., the first journal surface  302   a  of  FIG. 3 ) and a high local pressure is achieved that overcomes the seal contact pressure at the dynamic interface. This allows the lubricant  310  to migrate into the dynamic interface and thereby separate the dynamic surface  316   a  from the opposing surface. This also helps spread the lubrication  310  over a larger surface area on the dynamic surface  316   a . This continuous leak (discharge) of lubricant  310  helps maintain constant lubrication at the dynamic interface and also cleans contamination off the dynamic surface. 
       FIG. 5A  is an isometric view of another embodiment of the sealing element  250  of  FIGS. 2B and 3 , according to one or more embodiments. Similar to the sealing element  250  of  FIGS. 4A-4E , the sealing element  250  of  FIG. 5A  includes the annular body  400  that defines one or more inlet apertures  404  (four shown) in the second axial surface  312   b  and one or more outlet apertures  406  (two shown in  FIG. 5A ) in the dynamic surface  316   a . Moreover, the sealing element  250  of  FIG. 5A  may also include one or more slots  410  defined in the dynamic surface  316   a  and contiguous with each outlet aperture  406 . Unlike the sealing element  250  of  FIGS. 4A-4E , however, the slots  410  of the sealing element  250  of  FIG. 5A  are defined in the dynamic surface  316   a  at an angle with respect to the annular centerline  408  of the sealing element  250  or alternatively at an angle offset from perpendicular to the central axial  402 . 
       FIG. 5B  is an enlarged view of a portion of the dynamic surface  316   a . As shown in  FIG. 5B , the first and second furrows  412   a,b  extend from the outlet aperture  406  in opposing directions and at an angle  502  with respect to the annular centerline  408 . The angle  502  may range from 1° to 90° relative to the annular centerline  408 . As will be appreciated, increasing the magnitude of the angle  502  may prove advantageous in increasing the surface area on the opposing surface being swept by the furrows  412   a,b . Furthermore, with rotation of the sealing element  250  relative to the journal  222  ( FIG. 2B ), the angle  502  adds axial pumping and helps push the lubricant  310  ( FIG. 3 ) toward the first axial surface  312   a . more specifically, when the dynamic surface  316   a  moves (as in rotation) from left to right in  FIG. 5B , the slot  410  arranged at the angle  502  may help to push or urge the lubricant  310  toward the first axial surface  312   a  as compared to a slot that is parallel to the annular centerline  408 . 
       FIG. 6  is an isometric view of another embodiment of the sealing element  250  of  FIGS. 2B and 3 , according to one or more embodiments. Similar to prior embodiments of the sealing element  250 , the sealing element  250  of  FIG. 6  includes the annular body  400  that defines one or more inlet apertures  404  (eight shown) in the second axial surface  312   b  and one or more outlet apertures  406  (four shown) in the dynamic surface  316   a . Moreover, the sealing element  250  of  FIG. 6  may also include a plurality of slots  410  defined in the dynamic surface  316   a  and contiguous with each associated outlet aperture  406 . 
     Unlike the sealing element  250  of prior embodiments, however, the slots  410  of the sealing element  250  of  FIG. 6  are defined in the dynamic surface  316   a  at varying angles with respect to the annular centerline  408  ( FIGS. 4D and 5B ) of the sealing element  250 . More specifically, angularly adjacent slots  410  defined in the dynamic surface  316   a  may exhibit alternating angles with respect to the annular centerline  408 . In other embodiments, the angles of angularly adjacent slots  410  may not necessarily alternate, but they may be different nonetheless, without departing from the scope of the disclosure. The slots  410  configured at alternating angles may help maintain good lubrication of the underlying sealing areas on both angular sides of the outlet apertures  406 . 
       FIGS. 7A-7J  are cross-sectional end views of example designs for various sealing elements  700   a - 700   f  that may be used in accordance with the present disclosure. Each sealing element  700   a - 700   f  may be similar to the sealing element  250  of  FIG. 3  and therefore may be best understood with reference thereto, where like numerals represent like elements or components not described again. For instance, each sealing element  700   a - f  may provide the opposing first and second axial surfaces  312   a,b , the dynamic surface  316   a , and the outer radial surface  316   b . Each sealing element  700   a - f  may also provide a channel  320  extending between the second axial surface  312   b  and the dynamic surface  316   a  to convey the lubricant  310  ( FIG. 3 ) from the lubricant chamber  318  ( FIG. 3 ) directly to the interface between the dynamic surface  316   a  and an opposing surface (e.g., the first journal surface  302   a  of  FIG. 3 ). Each lubricant channel  320  may further include the inlet and outlet apertures  404 ,  406 , as generally described above. 
     In  FIG. 7A , the lubricant channel  320  is defined as a curved or arcuate conduit extending between the second axial surface  312   b  and the dynamic surface  316   a . In at least one embodiment, as illustrated, portions of the lubricant channel  320  may be straight as well as curved. In  FIG. 7B , the lubricant channel  320  is defined as a straight conduit or passageway extending between the second axial surface  312   b  and the dynamic surface  316   a  at an angle  701  relative to one or both of the second axial surface  312   b  and the dynamic surface  316   a . The angle  701  of the lubricant channel  320  may vary, depending on the application, but will nonetheless extend between the second axial surface  312   b  and the dynamic surface  316   a.    
     In  FIG. 7C , the lubricant channel  320  provides an axial channel  702   a  extending from the second axial surface  312   b  and a radial channel  702   b  extending from the dynamic surface  316   a  and intersecting at a location within the interior of the sealing element  700   c . As illustrated, the axial channel  702   a  extends from the second axial surface  312   b  substantially parallel to the dynamic surface  316   a . The radial channel  702   b  may extend at an angle  704  offset from perpendicular to the dynamic surface  316   a . In alternative embodiments, the axial channel  702   a  may instead extend from the dynamic surface  316   a  at an angle offset from parallel to the dynamic surface  316   a  while the radial channel  702   b  may extend perpendicular to the dynamic surface  316   a . In yet other embodiments, both the axial and radial channels  702   a,b  may extend at corresponding angles offset from parallel and perpendicular, respectively, to the dynamic surface  316   a , without departing from the scope of the disclosure. 
     In  FIG. 7D , the lubricant channel  320  is formed in the sealing element  700   d  by removing contiguous sections of the second axial surface  312   b  and the dynamic surface  316   a  such that a corner section of the sealing element  700   d  is excised. In this embodiment, the inlet and outlet apertures  404 ,  406  form a contiguous passageway. 
     In  FIGS. 7E and 7F , the lubricant channel  320  includes an annular conduit  706  that fluidly communicates an axial channel  708   a  extending from the second axial surface  312   b  with a radial channel  708   b  extending from the dynamic surface  316   a . Accordingly, the axial and radial channels  708   a,b  intersect and otherwise fluidly communicate at the annular conduit  706 . The annular conduit  706  comprises an annular passageway defined within and otherwise extending through the entire annular body of the sealing elements  700   e,f . The annular conduit  706  of  FIG. 7E  may be molded into the sealing element  700   e  during the manufacturing process. The annular conduit  706  of  FIG. 7F , however, may comprise a tube or pipe  710  and the sealing element  700   f  may be molded around the pipe  710 . 
     In some embodiments, the axial and radial channels  708   a,b  may be molded into the sealing elements  700   e,f  during the manufacturing process. In other embodiments, however, the axial and radial channels  708   a,b  may be machined (e.g., drilled) into the sealing elements  700   e,g  and thereby locate and tap into the annular conduit  706  at their respective locations. 
     In operation, the lubricant  310  ( FIG. 3 ) enters the lubricant channel  320  at the inlet aperture  404  and flows to the annular conduit  706  via the axial channel  708   a . The lubricant  310  may then fill the annular conduit  706  and distribute the lubricant to the radial channel  708   b  to be discharged via the outlet aperture  406 . The sealing elements  700   e,f  may generate a pumping action as the sealing element  700   e,f  is rotated from the loaded to the unloaded side of the bearing, similar to operation of a peristaltic pump. Accordingly, in some embodiments, the sealing elements  700   e,f  may require only one inlet aperture  404  and an associated axial channel  708   a  that feeds the lubricant  310  to the annular conduit  706 . In such embodiments, the sealing elements  700   e,f  may include one or multiple radial channels  708   b  and associated outlet apertures  406  to dispense the lubricant  310  from the annular conduit  706  at the dynamic interface. 
     In  FIGS. 7G and 7H , the lubricant channel  320  comprises an axial channel  712   a  extending from the second axial surface  312   b  with a radial channel  712   b  extending from the dynamic surface  316   a . The axial and radial channels  712   a,b  intersect and otherwise fluidly communicate at a point in the interior of the sealing element  700   g  and  700   h . In the illustrated embodiment, the walls of the lubricant channel  320  are not necessarily parallel at all locations. Rather, as illustrated, at least a portion of the walls of the radial channel  712   b  may vary, such as at a tapered section  714 . In  FIG. 7G , the tapered section  714  is located at or near the outlet aperture  406 , and in  FIG. 7H , the tapered section  714  is located at or near the inlet aperture  404 . In other embodiments, the lubricant channel  320  may include the tapered section  714  at both the inlet and outlet apertures  404 ,  406 . 
     The tapered section  714  may be large enough for the lubricant channel  320  to remain open when the sealing element  700   g  is compressed, or the lubricant channel  320  may alternatively close upon being compressed. When the lubricant channel  320  is compressed to close the inlet or outlet apertures  404 ,  406 , the lubricant channel  320  may act as a lubricant reservoir initially, but as the sealing element  700   g  wears, the inlet or outlet apertures  404 ,  406  will gradually open and thereby allow communication between the second axial surface  312   b  and the dynamic surface  316   a  to decrease friction in the worn state. Accordingly, the sealing elements  700   g  and  700   h  may operate as a type of valve that may be opened after an amount of wear has occurred, and enough wear to open the inlet or outlet apertures  404 ,  406  to facilitate discharge of the lubricant  310  ( FIG. 3 ). 
     In embodiments where the sealing elements  700   g,h  exhibits an oval or elliptical cross-section, the wear on the sealing element  700   g,h  may allow operation as a valve. More specifically, an oval sealing element  700   g,h  may be aligned such that when it is under compression the tapered section  714  opens or when the compression is perpendicular the tapered section  714  closes. These orientations would allow the oval sealing element  700   g,h  acting as a valve to open or close as the sealing element  700   g,h  wears and compression is gradually relieved. 
     In  FIGS. 7I and 7J , the lubricant channel  320  comprises an axial channel  716   a  extending from the second axial surface  312   b  with a radial channel  716   b  extending from the dynamic surface  316   a . The axial and radial channels  716   a,b  intersect and otherwise fluidly communicate at a point in the interior of the sealing elements  700   i  and  700   j . The sealing elements  700   i,j  may further each include a valve member  718  positioned within the lubricant channel  320 . 
     In  FIG. 7I , the valve member  718  may comprise a flap  720  coupled to the wall of at least one of the axial and radial channels  716   a,b . In the illustrated embodiment, the flap  720  is depicted as being coupled to and otherwise extending from the radial channel  716   b . The flap  720  may be flexible and operate as a one-way valve that allows the lubricant  310  to flow from the inlet aperture  404  to the outlet aperture  406 , but prevent the lubricant  310  from flowing in the reverse direction. 
     In  FIG. 7J , the valve member  718  may comprise a funnel  722  positioned within at least one of the axial and radial channels  716   a,b . In the illustrated embodiment, the funnel  722  is depicted as being positioned within the axial channel  716   a . The funnel  722  may also operate as a one-way valve that allows the lubricant  310  to flow from the inlet aperture  404  to the outlet aperture  406 , but prevent the lubricant  310  from flowing in the reverse direction. The sealing element  700   j , however, may further include a choke  724  arranged at the inlet aperture  404 . The choke  720  may be characterized as a reduced diameter section of the axial channel  716   a . In embodiments where the sealing element  700   j  rotates, the choke  724  may be designed to open at an unloaded side and close at a loaded side, which may cause a pumping action to the flow of the lubricant. At the unloaded side, the choke  724  may open and draw in the lubricant  310  and, as the sealing element  700   j  rotates to the loaded side, the choke  724  may be configured to close as the sealing element  700   j  is compressed, which results in the lubricant  310  being squeezed or discharged out the outlet aperture  406 . 
       FIGS. 8A and 8B  are enlarged views of a portion of the dynamic surface  316   a  of additional example sealing elements  800   a  and  800   b , according to one or more embodiments. Each sealing element  800   a,b  may be similar to the sealing element  250  of  FIGS. 3 and 4A-4F  and therefore may be best understood with reference thereto, where like numerals represent like elements or components not described again. Each sealing element  800   a,b  may provide the opposing first and second axial surfaces  312   a,b  and the dynamic surface  316   a . Moreover, each sealing element  800   a,b  may also provide at least one slot  802  defined in the dynamic surface  316   a  and contiguous with an associated outlet aperture  406 . Similar to the slots  410  described above with reference to  FIGS. 4A-4F , each slot  802  generally comprise a recess formed on the dynamic surface  316   a  that connects the outlet aperture  406  to the dynamic surface  316   a.    
     In  FIG. 8A , the slot  802  includes a single furrow  804  extending from the outlet aperture  406  in a first direction along the arcuate length of the dynamic surface  316   a . In other embodiments, the furrow  804  may extend from the outlet aperture  406  in a second direction opposite the first direction, without departing from the scope of the disclosure. The design and description of the furrow  804  may be similar to the first or second furrows  412   a,b  of  FIGS. 4C-4E  and, therefore, will not be described again in detail. 
     In  FIG. 8B , the slot  802  may include a first furrow  806   a  extending from the outlet aperture  406  in a first direction and a second furrow  806   b  extending from the outlet aperture  406  in a second direction opposite the first direction and along the arcuate length of the dynamic surface  316   a . Similar to the slots  410  of  FIGS. 4A-4E , the depth of each furrow  806   a,b  may vary extending from the outlet aperture  406  in each direction and otherwise along the arcuate length of the dynamic surface  316   a . Unlike the first and second furrows  412   a,b  of  FIGS. 4C-4E , however, which each exhibit a generally teardrop shape, the first and second furrows  806   a,b  may each exhibit a generally polygonal shape with rounded corners or edges. Those skilled in the art will appreciate that other shapes may be employed for the furrows  806   a,b , without departing from the scope of the disclosure. Moreover, in some embodiments, the first and second furrows  806   a,b  may exhibit different shapes. 
       FIGS. 9A-9C  are cross-sectional end views of example sealing elements  900   a ,  900   b , and  900   c , respectively, that may be used according to the principles of the present disclosure. Each sealing element  900   a - c  may be similar to the sealing element  250  of  FIG. 3  and therefore may be best understood with reference thereto, where like numerals represent like elements or components not described again. For instance, each sealing element  900   a - c  may provide the opposing first and second axial surfaces  312   a,b , the dynamic surface  316   a , and the outer radial surface  316   b . Whereas the sealing elements shown in any of the prior figures each exhibit a generally polygonal cross-sectional end shape with rounded corner or edges (see, for example,  FIGS. 7A-7F ), the sealing elements  900   a - c  of  FIG. 9A-9C  may exhibit different cross-sectional end shapes. 
     In  FIG. 9A , for example, the cross-sectional end shape of the sealing element  900   a  may be generally polygonal (i.e., rectangular) with angled portions  902   a  and  902   b  excised from one or both of the first and second axial surfaces  312   a,b . This reduces the contact area of the dynamic surface  316   a  while providing stability and compliance. 
     In  FIG. 9B , the cross-sectional end shape of the sealing element  900   b  may be generally circular or ovoid (i.e., oval). Accordingly, in such embodiments, the sealing element  900   b  may be characterized as an O-ring or the like. The sealing element  900   b  may prove advantageous in being in the form of general industry standard, which is simple to make and, therefore, less expensive. 
     In  FIG. 9C , the cross-sectional end shape of the sealing element  900   c  may be generally polygonal (i.e., rectangular), but portions of one or more of the first and second axial surfaces  312   a,b , the dynamic surface  316   a , and the outer surface  316   b  may be removed. As illustrated, for example, the one or both of the first and second axial surfaces  312   a,b  may define side grooves  904   a  and  904   b . The side grooves  904   a,b  may be arcuate (i.e., rounded) or include sharp angled surfaces (i.e., polygonal). In some embodiments, the side grooves  904   a,b  may be defined on the first and second axial surfaces  312   a,b  along the entire circumference of the sealing element  900   c . In other embodiments, however, the side grooves  904   a,b  may be defined on the first and second axial surfaces  312   a,b  along only a portion of the circumference of the sealing element  900   c.    
     In some embodiments, as illustrated, one or both of the dynamic surface  316   a  and the outer radial surface  316   b  may also include a groove  906   a  and  906   b . Similar to the side grooves  904   a,b , the grooves  906   a,b  may be arcuate (i.e., rounded) or may alternatively include sharp angled surfaces (i.e., polygonal). The groove  906   a  defined on the dynamic surface, in particular, may exhibit various shapes including, but not limited to, a v-channel, a concave shape, a convex shape, and any combination thereof. In some embodiments, the grooves  906   a,b  may be defined on the dynamic surface  316   a  and the outer radial surface  316   b , respectively, along the entire inner and outer radial surfaces of the sealing element  900   c . In other embodiments, however, the grooves  906   a,b  may be defined on the dynamic surface  316   a  and the outer radial surface  316   b , respectively, along only a portion of the inner and outer radial surfaces of the sealing element  900   c . As will be appreciated, the side grooves  904   a,b  and the grooves  906   a,b  may prove advantageous in reducing the contact area and reducing contact pressure as well as friction of the dynamic surface  316   a  while providing compliance with multiple defined boundaries separating the mud and the lubricant. 
     In some embodiments, the dynamic surface  316   a  may further include or otherwise define one or more surface features. Example surface features that may be included on the dynamic surface  916   a  include, but are not limited to, texture, dimples, undulations, cross-hatching, waves, and any combination thereof. Those skilled in the art will readily recognize that such surface features may minimize surface contact at the dynamic interface, which minimizes friction. 
       FIG. 10  is an enlarged cross-sectional side view of a portion of the drill bit  200  of  FIG. 2B  showing another example embodiment of a sealing element  250 , referenced in  FIG. 10  at  1000 , and as received within the seal groove  252 . As generally described above, the lubricant  310  is pumped into the gap  308  to lubricate the interface between the journal  222  and the roller cone  226 , and subsequently enter the seal groove  252  to provide lubrication for the dynamic sealing engagement provided by the sealing element  1000 . 
     The sealing element  1000  may be similar in some respects to the sealing element  250  described above and therefore may be best understood with reference thereto, where like numerals will correspond to like components or elements. For instance, the sealing element  1000  may be made of the same materials as the sealing element  250 . Moreover, as illustrated, the sealing element  1000  includes the first and second axial surfaces  312   a,b  and the opposing inner and outer radial surfaces  316   a,b.    
     Unlike the sealing element  250  of  FIG. 3 , however, the sealing element  1000  of  FIG. 10  is configured as an axial seal where the first and second axial surfaces  312   a,b  provide sealed interfaces against opposing surfaces of the seal groove  252  during operation. More specifically, the first axial surface  312   a  is configured to sealingly engage the second journal surface  302   b , while the second axial surface  312   b  is configured to sealingly engage the second cone surface  306   b . The sealing element  1000  is maintained under sufficient axial compression to ensure maintenance of a seal at the interface between the first axial surface  312   a  and the second journal surface  302   b  and the interface between the second axial surface and the second cone surface  306   b.    
     The sealing element  1000  may be configured to rotate with rotation of the roller cone  226  or may alternatively remain stationary with the journal  222 . In embodiments where the sealing element  1000  rotates with the roller cone  226  relative to the journal  222 , the first axial surface  312   a  will be characterized as a “dynamic surface.” In contrast, in embodiments where the sealing element  1000  remains stationary with the journal  222  relative to the roller cone  226 , the second axial surface  312   b  will be characterized as the “dynamic surface.” For purposes of the present description, however, it will be assumed that the sealing element  1000  rotates with the roller cone  226  relative to the journal  222  and, therefore, the first axial surface  312   a  will be referred to herein as the “dynamic surface  312   a .” It will be appreciated, however, that the principles of the present disclosure are equally applicable to embodiments where the second axial surface  312   b  serves as the dynamic surface, without departing from the scope of the disclosure. 
     In some embodiments, as illustrated, the inner radial surface  316   a  is spaced from the first journal surface  302   a  and thereby defines the lubricant chamber  318  within the seal groove  252 . During operation, the lubricant  310  is pumped or otherwise conveyed into the lubricant chamber  318 . Accordingly, the inner radial surface  316   a  will be exposed to the lubricant  310  entering the seal groove  252  via the gap  308  and, therefore, may be referred to and otherwise characterized as a “lubricant surface.” 
     The sealing element  1000  may provide a lubricant channel  1002  that extends between the inner radial surface  316   a  and the dynamic surface  312   a . The lubricant channel  1002  may be machined into the sealing element  1000  or may alternatively be molded into the sealing element  1000  during manufacture. The lubricant channel  1002  provides a fluid passageway or conduit configured to convey the lubricant  310  from the lubricant chamber  318  directly to the dynamic surface  312   a  (i.e., the interface between the dynamic surface  312   a  and the second journal surface  302   b ) and at a radial location between the inner and outer radial surfaces  316   a,b.    
     In the illustrated embodiment, a radial channel  1004   a  and an axial channel  1004   b  jointly define the lubricant channel  1002 . The radial channel  1004   a  extends from the inner radial surface  316   a  and the axial channel  1004   b  extends from the dynamic surface  312   a  and is substantially perpendicular to the radial channel  1004   a . The radial and axial channels  1004   a,b  intersect at a location within the interior of the sealing element  1000  to facilitate fluid communication from the lubricant chamber  318  to the dynamic surface  312   a.    
     Similar to the sealing element  250  of  FIG. 3 , several variations and designs of the sealing element  1000  and the lubricant channel  1002  may be employed without departing from the scope of the disclosure. The following figures and discussion provide various contemplated designs and configurations for the sealing element  1000  and the lubricant channel  1002 , but should not be considered as limiting the scope of the disclosure. Rather, those skilled in the art will readily recognize that other designs and configurations could equally be used in keeping with the principles described herein. 
       FIGS. 11A-11E  are various views of the sealing element  1000  of  FIG. 10 , according to one or more embodiments. As illustrated in  FIG. 11A , the sealing element  1000  comprises an annular body  1100  that provides the opposing inner and outer radial surfaces  316   a,b , the dynamic surface  312   a , and the second axial surface  312   b . The annular body  1100  also provides a central axis  1102 . One or more inlet apertures  1104  (two shown in  FIG. 11A ) may be defined in the inner radial surface  316   a  and one or more outlet apertures  1106  (four shown in  FIG. 11A ) may be defined in the dynamic surface  312   a  (i.e., the first axial surface). 
       FIG. 11B  is a partial cross-sectional view of the sealing element  1000  as taken through angularly opposite channels  1002 , and  FIG. 11C  is an enlarged cross-sectional view of the sealing element  1000  as taken through one of the channels  1002 . Each inlet and outlet aperture  1104 ,  1106  provides access into a corresponding channel  1002  extending between the inner radial surface  316   a  and the dynamic surface  312   a . Each lubricant channel  1002  includes the radial channel  1004   a  extending from the inner radial surface  316   a  and the axial channel  1004   b  extending from the dynamic surface  312   a  and intersecting at a location within the interior of the sealing element  1000  to facilitate fluid communication from the lubricant chamber  318  ( FIG. 10 ) to the dynamic surface  312   a . In some embodiments, the axial channel  1004   b  may extend from the dynamic surface  312   a  substantially parallel to the central axis  1102  ( FIG. 11A ), and the radial channel  1004   b  may extend substantially perpendicular to both the radial channel  1004   a  and the central axis  1102 . It will be appreciated, however, that the radial and axial channels  1004   a,b  may alternatively extend at various other angles and nonetheless provide fluid communication between the inner radial surface  316   a  and the dynamic surface  312   a , without departing from the scope of the disclosure. 
       FIG. 11D  is an enlarged view of a portion of the dynamic surface  312   a . In some embodiments, the outlet aperture  1106  defined in the dynamic surface  312   a  may be offset from an annular centerline  1108  of the sealing element  1000 . The annular centerline  1108  is the radial midpoint of the contact area of the sealing element  1000  between the inner and outer radial surfaces  316   a,b . In the illustrated embodiment, the outlet aperture  1106  is defined in the dynamic surface  312   a  at a location that is radially offset from the annular centerline  1108  and radially closer to the inner radial surface  316   a . In other embodiments, however, the outlet aperture  1106  may be radially offset from the annular centerline  1108  and radially closer to the outer radial surface  316   b , or aligned with the annular centerline  1108 , without departing from the scope of the disclosure. 
     Having the outlet aperture  1106  located radially closer to the inner radial surface  316   a , as compared to being closer to the outer radial surface  316   b , may prove advantageous in prolonging the operational lifespan of the sealing element  1000 . More specifically, a slurry of abrasive particulates will commonly form at the outer radial surface  316   b  during operation, and will progressively erode away at the annular body  1100  (FIGS.  11 A- 11 B) on the outer radial surface  316   b  as the sealing element  1000  rotates (or as an opposing surface/substrate rotates). Eventually the axial thickness of the annular body  1100  will erode away enough to reach the outlet aperture  1106 , which could adversely affect the sealing performance of the sealing element  1000 . Placing the outlet aperture  1106  closer to the inner radial surface  316   a , however, provides the sealing element  1000  with a longer operational lifespan until the erosion reaches the outlet aperture  1106 . Assuming the distance between the inner and outer radial surfaces  316   a,b  can be characterized as a percentage of radial distance between the two, the outer radial surface  316   b  may be located at 100% of the radial distance and the inner radial surface  316   a  may be located at 0%. In such a measurement scenario, the outlet aperture  1106  may be located at a distance between about 49% and 10% of the radial distance between the inner and outer radial surfaces  316   a,b.    
     Similar to the sealing element  250 , in some embodiments, each lubricant channel  1002  may also include a slot  1110 . In the illustrated embodiment, however, the slot  1110  is defined in the dynamic surface  312   a  and contiguous with the outlet aperture  1106 . As described above, each slot  1110  comprises a recess formed on the dynamic surface  312   a  that connects the outlet aperture  1106  to the dynamic surface  312   a . The slot  1110  exhibits a length L and a width W where, in the illustrated embodiment, the length L extends generally along the arcuate length of the dynamic surface  312   a  and the width W extends generally in the radial direction between the opposing inner and outer radial surfaces  316   a,b.    
     As illustrated, the slot  1110  may include the first and second furrows  412   a,b , as generally described above. In other embodiments, however, only one furrow  412   a,b  may be included. In some embodiments, as illustrated, the first and second furrows  412   a,b  may extend parallel to a tangent to the outer radial surface  316   a . In other embodiments, the first and second furrows  412   a,b  may extend at an angle to a tangent to the outer radial surface  316   a , similar to the angle  502  of  FIG. 5B ). In at least one embodiment, however, one or both of the furrows  412   a,b  may extend at an arcuate angle along the dynamic surface and otherwise parallel to the annular centerline  108 , as shown in the dashed lines  1112   a  and  1112   b.    
       FIG. 11E  is a cross-sectional side view of the sealing element  1000  as taken along the lines  11 E- 11 E in  FIG. 11D . The depth of each furrow  412   a,b  may vary as extending from the outlet aperture  1106  in each direction and otherwise along the arcuate length of the dynamic surface  312   a . In the illustrated embodiment, for example, each furrow  412   a,b  tapers radially inward and toward the dynamic surface  312   a  as extending in each corresponding direction away from the outlet aperture  1106 . Consequently, the depth of the furrows  412   a,b  may be deepest near the outlet aperture  1106  and tapers to zero or flush with the dynamic surface  312   a  at the ends of the length L ( FIG. 11D ). 
     The slots  1110  may prove advantageous for inducing hydroplaning during operation of the sealing element  1000 . More particularly, the lubricant  310  ( FIG. 10 ) exits the outlet aperture  1106  and is fed into the furrows  412   a,b  during operation. The lubricant  310  is continuously expressed (discharged) onto the opposing stationary or dynamic surface (e.g., the first journal surface  302   a  of  FIG. 10 ) and a high local pressure is achieved that overcomes the seal contact pressure at the dynamic interface. This allows the lubricant  310  to migrate into the dynamic interface and thereby separate the dynamic surface  312   a  from the opposing surface. This also helps spread the lubrication  310  over a larger surface area on the dynamic surface  312   a . This continuous leak (discharge) of lubricant  310  helps maintain constant lubrication at the dynamic interface and also cleans contamination off the dynamic surface. 
     It will be appreciated that the lubricant channel  1002  in the sealing element  1000  may conform to various configurations, without departing from the scope of the disclosure. For example, any of the configurations of the lubricant channel  320  shown in  FIGS. 7A-7J  may be equally applicable to the lubricant channel  1002  of the sealing element  1000  and, therefore, will be not be discussed again in detail. Moreover, the design and configurations of the slots  1110  of the sealing element  1000  may conform to the various configurations and designs of the slots  802  shown in  FIGS. 8A-8B . Furthermore, the cross-sectional end shape of the sealing element  1000  may vary depending on the application, and may be similar to any of the cross-sectional end shapes of the sealing elements  900   a - c  of  FIGS. 9A-9C , without departing from the scope of the disclosure. 
     Embodiments disclosed herein include: 
     A. A seal assembly that includes a seal groove defined at least partially between a first member and a second member rotatable relative to the first member, an annular sealing element positioned in the seal groove and providing a mud surface, a lubricant surface axially opposite the mud surface, an inner radial surface, and an outer radial surface radially opposite the inner radial surface, wherein one of the inner and outer radial surfaces is a dynamic surface that seals against the first member when the sealing element rotates with the second member, or seals against the second member when the second member rotates relative to the sealing element, and a lubricant channel defined through the sealing element and extending between the lubricant surface and the dynamic surface to provide a lubricant to the dynamic surface. 
     B. A sealing element that includes an annular body having a mud surface, a lubricant surface axially opposite the mud surface, an inner radial surface, and an outer radial surface radially opposite the inner radial surface, wherein one of the inner and outer radial surfaces is a dynamic surface that seals against a stationary surface of a first member when the sealing element is rotated with a second member rotatable relative to the first member, or seals against a rotating surface of the second member when the second member rotates relative to the sealing element, an inlet aperture defined on the lubricant surface, an outlet aperture defined on the dynamic surface, and a lubricant channel defined through the annular body and extending between the inlet aperture and the outlet aperture to facilitate communication of a lubricant to the dynamic surface from the lubricant surface. 
     C. A seal assembly that includes a seal groove defined at least partially between a first member and a second member rotatable relative to the first member, a sealing element positioned in the seal groove and providing an annular body having a first axial side, a second axial side axially opposite the first axial side, an inner radial surface, and an outer radial surface radially opposite the inner radial surface, wherein one of the first and second axial sides is a dynamic surface that seals against a stationary surface of the first member when the sealing element is rotated with the second member, or seals against a rotating surface of the second member when the second member rotates relative to the sealing element, and a lubricant channel defined through the sealing element and extending between the inner radial surface and dynamic surface to provide a lubricant to the dynamic surface. 
     D. A sealing element that includes an annular body having a first axial side, a second axial side opposite the first axial side, an inner radial surface, and an outer radial surface opposite the inner radial surface, wherein one of the first and second axial sides is a dynamic surface that seals against a stationary surface of a first member as the sealing element is rotated with a second member, or seals against a rotating surface of the second member as the second member rotates relative to the sealing element, an inlet aperture defined on the inner radial surface, an outlet aperture defined on the dynamic surface, and a lubricant channel defined through the sealing element and extending between the inlet aperture and the outlet aperture to facilitate communication of a lubricant to the dynamic surface from the inner radial surface. 
     Each of embodiments A, B, C, and D may have one or more of the following additional elements in any combination: Element 1: further comprising a lubricant chamber defined between the lubricant surface and a wall of the seal groove, wherein the lubricant channel conveys the lubricant from the lubricant chamber directly to a dynamic interface between the dynamic surface and the first member or the second member. Element 2: wherein the first member is a journal of a roller cone drill bit and the second member is a roller cone of the roller cone drill bit. Element 3: wherein the lubricant channel is a first lubricant channel and extends to a first outlet aperture defined on the dynamic surface, the seal assembly further comprising a second lubricant channel defined through the sealing element and extending between the lubricant surface and a second outlet aperture defined on the dynamic surface, a first slot defined in the dynamic surface and contiguous with the first outlet aperture, wherein the first slot provides at least one furrow that extends from the first outlet aperture, and a second slot defined in the dynamic surface and contiguous with the second outlet aperture, wherein the second slot provides at least one furrow that extends from the second outlet aperture. 
     Element 4: wherein the lubricant channel comprises an axial channel extending from the lubricant surface and a radial channel extending from the dynamic surface. Element 5: wherein at least a portion of the lubricant channel is curved. Element 6: wherein the lubricant channel comprises a straight conduit extending between the lubricant surface and the dynamic surface at an angle relative to the dynamic surface. Element 7: wherein the lubricant channel comprises an annular conduit extending within the annular body, one or more axial channels extending from the lubricant surface and fluidly communicating with the annular conduit, and one or more radial channels extending from the dynamic surface and fluidly communicating with the annular conduit. Element 8: wherein the annular conduit comprises an annular tube and the body is molded around the tube. Element 9: wherein the outlet aperture is offset from an annular centerline of the body and axially closer to the lubricant surface as compared to the mud surface. Element 10: further comprising a slot defined in the dynamic surface and contiguous with the outlet aperture. Element 11: wherein the slot provides at least one furrow that extends from the outlet aperture along an arcuate length of the dynamic surface, and wherein the at least one furrow tapers radially inward and toward the dynamic surface as extending away from the outlet aperture. Element 12: wherein the at least one furrow extends at an angle offset from parallel with an annular centerline of the sealing element. Element 13: wherein a side groove is defined on one or both of the mud and lubricant surfaces. Element 14: wherein the lubricant channel defines a tapered section at or near the outlet aperture. Element 15: further comprising a valve member positioned within the lubricant channel. Element 16: further comprising a choke positioned within the lubricant channel. 
     Element 17: wherein the first member is a journal of a roller cone drill bit and the second member is a roller cone of the roller cone drill bit. Element 18: wherein the lubricant channel is a first lubricant channel and extends to a first outlet aperture defined on the dynamic surface, the seal assembly further comprising a second lubricant channel defined through the sealing element and extending between the inner radial surface and a second outlet aperture defined on the dynamic surface, a first slot defined in the dynamic surface and contiguous with the first outlet aperture, wherein the first slot provides at least one furrow that extends from the first outlet aperture, and a second slot defined in the dynamic surface and contiguous with the second outlet aperture, wherein the second slot provides at least one furrow that extends from the second outlet aperture. 
     Element 19: wherein the lubricant channel comprises a radial channel extending from the lubricant surface and an axial channel extending from the dynamic surface. Element 20: wherein the lubricant channel comprises an annular conduit extending within the annular body, one or more axial channels extending from the lubricant surface and fluidly communicating with the annular conduit, and one or more radial channels extending from the dynamic surface and fluidly communicating with the annular conduit. Element 21: wherein the outlet aperture is offset from an annular centerline of the sealing element and radially closer to the lubricant surface as compared to the second axial end. Element 22: further comprising a slot defined in the dynamic surface and contiguous with the outlet aperture. Element 23: wherein the slot provides at least one furrow that extends from the outlet aperture along an arcuate length of the dynamic surface, and wherein the at least one furrow tapers radially inward and toward the dynamic surface as extending away from the outlet aperture. 
     By way of non-limiting example, exemplary combinations applicable to A, B, C, and D include: Element 4 with Element 5; Element 7 with Element 8; Element 10 with Element 11; and Element 11 with Element 12. 
     Therefore, the disclosed systems and methods are well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the teachings of the present disclosure may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered, combined, or modified and all such variations are considered within the scope of the present disclosure. The systems and methods illustratively disclosed herein may suitably be practiced in the absence of any element that is not specifically disclosed herein and/or any optional element disclosed herein. While compositions and methods are described in terms of “comprising,” “containing,” or “including” various components or steps, the compositions and methods can also “consist essentially of” or “consist of” the various components and steps. All numbers and ranges disclosed above may vary by some amount. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range is specifically disclosed. In particular, every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles “a” or “an,” as used in the claims, are defined herein to mean one or more than one of the elements that it introduces. If there is any conflict in the usages of a word or term in this specification and one or more patent or other documents that may be incorporated herein by reference, the definitions that are consistent with this specification should be adopted. 
     As used herein, the phrase “at least one of” preceding a series of items, with the terms “and” or “or” to separate any of the items, modifies the list as a whole, rather than each member of the list (i.e., each item). The phrase “at least one of” allows a meaning that includes at least one of any one of the items, and/or at least one of any combination of the items, and/or at least one of each of the items. By way of example, the phrases “at least one of A, B, and C” or “at least one of A, B, or C” each refer to only A, only B, or only C; any combination of A, B, and C; and/or at least one of each of A, B, and C.