Patent Publication Number: US-10760342-B2

Title: Rolling element assembly with a compliant retainer

Description:
BACKGROUND 
     In conventional wellbore drilling in the oil and gas industry, a drill bit is mounted on the end of a drill string, which may be extended by adding segments of drill pipe as the well is progressively drilled to the desired depth. At the surface of the well site, a rotary drive (referred to as a “top drive”) may be provided to rotate the entire drill string, including the drill bit at the end, to drill through the subterranean formation. Alternatively, the drill bit may be rotated using a downhole mud motor without having to rotate the drill string. When drilling, drilling fluid is pumped through the drill string and discharged from the drill bit to remove cuttings and debris. The mud motor, if present in the drill string, may be selectively powered using the circulating drilling fluid. 
     One common type of drill bit used to drill wellbores is a “fixed cutter” bit, wherein the cutters are secured to the bit body at fixed positions. This type of bit is sometimes referred to as a “drag bit” since the cutters in one respect drag rather than roll in contact with the formation during drilling. The bit body may be formed from a high strength material, such as tungsten carbide, steel, or a composite/matrix material. A plurality of cutters (also referred to as cutter elements, cutting elements, or inserts) is attached at selected locations about the bit body. The cutters may include a substrate or support stud made of a carbide (e.g., tungsten carbide), and an ultra-hard cutting surface layer or “table” made of a polycrystalline diamond material or a polycrystalline boron nitride material deposited onto or otherwise bonded to the substrate. Such cutters are commonly referred to as polycrystalline diamond compact (“PDC”) cutters. 
     In fixed cutter drill bits, PDC cutters are rigidly secured to the bit body, such as by being brazed within corresponding cutter pockets defined on blades that extend from the bit body. Some of the PDC cutters are strategically positioned along the leading edges of the blades to engage the formation during drilling. In use, high forces are exerted on the PDC cutters, particularly in the forward-to-rear direction. Over time, the working surface or cutting edge of each cutter that continuously contacts the formation eventually wears down and/or fails. 
    
    
     
       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. 1A  illustrates an isometric view of a rotary drill bit that may employ the principles of the present disclosure. 
         FIG. 1B  illustrates an isometric view of a portion of the rotary drill bit enclosed in the indicated box of  FIG. 1A . 
         FIG. 1C  illustrates a drawing in section and in elevation with portions broken away showing the drill bit of  FIG. 1 . 
         FIG. 1D  illustrates a blade profile that represents a cross-sectional view of a blade of the drill bit of  FIG. 1 . 
         FIG. 2  is a partial cross-sectional, isometric view of one example of a rolling element assembly. 
         FIG. 3  is a partial cross-sectional side view of the rolling element assembly of  FIG. 2 . 
         FIG. 4  is a partial cross-sectional side view of another embodiment of the rolling element assembly of  FIG. 2 . 
         FIG. 5  is a partial cross-sectional side view of another embodiment of the rolling element assembly of  FIG. 2 . 
         FIG. 6  is a partial cross-sectional, isometric view of another example embodiment of the rolling element assembly of  FIG. 2 . 
         FIG. 7  is a partial cross-sectional side view of another embodiment of the rolling element assembly of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure relates to earth-penetrating drill bits and, more particularly, to rolling type depth of cut control elements that can be used in drill bits. 
     The present disclosure includes rolling element assemblies that can be secured within corresponding cavities provided on a drill bit. Each rolling element assembly may include a cylindrical rolling element strategically positioned and secured to the drill bit so that the rolling element is able to engage the formation during drilling. In response to drill bit rotation, and depending on the selected positioning (orientation) of the rolling element with respect to the body of the drill bit, the rolling element may roll against the underlying formation, cut against the formation, or may both roll against and cut the formation. The rolling elements of the presently disclosed rolling element assemblies are retained within corresponding cavities on the bit body using an arcuate retainer received within a retainer cavity defined in the cavity. 
     Example rolling element assemblies described herein can include a rolling element rotatable about a rotational axis within a cavity defined in a bit body, and a compliant retainer positioned within a retainer slot defined in the bit body. A biasing device may be positioned within a device pocket defined within the bit body to bias the compliant retainer against the outer circumferential surface of the rolling element. The compliant retainer helps to secure the rolling element within the cavity while an arcuate portion of the rolling element protrudes from the cavity and exposes a full axial width of the rolling element. The compliant retainer may be designed so that it will be retained during drilling operations but easily removed for repair operations. 
     The orientation of each rolling element with respect to the bit body is selected to produce a variety of different functions and/or effects. The selected orientation includes, for example, a selected side rake and/or a selected back rake. In some cases while drilling, the rolling element may be configured as a rolling cutting element that both rolls along the formation (e.g., by virtue of a selected range of side rake) and cuts the formation (e.g., by virtue of the selected back rake and/or side rake). More particularly, the rolling cutting element may be positioned to cut, dig, scrape, or otherwise remove material from the formation using a portion of the rolling element (e.g., a polycrystalline diamond table) that is positioned to engage the formation. 
     In some example embodiments, the rolling element assemblies described herein can be configured as rolling cutting elements. The rolling cutting elements may be configured to rotate freely about a rotational axis and, as a result, the entire outer edge of the rolling cutting element may be used as a cutting edge. Consequently, rather than only a limited portion of the cutting edge being exposed to the formation during drilling, as in the case of conventional fixed cutters, the entire outer edge of the rolling cutting element will be successively exposed to the formation as it rotates about its rotational axis during drilling. This results in a more uniform cutting edge wear, which may prolong the operational lifespan of the rolling cutting element as compared to conventional cutters. 
     In other example embodiments, the rolling element assemblies described herein can be configured as rolling depth of cut control (DOCC) elements that roll along the formation as the drill bit rotates. In a rolling DOCC element configuration, the orientation of the rolling element may be selected so that a full axial span of the rolling element bears against the formation. As with rolling cutting elements, rolling DOCC elements may exhibit enhanced wear resilience and allow for additional weight-on-bit without negatively affecting torque-on-bit. This may allow a well operator to minimize damage to the drill bit, thereby reducing trips and non-productive time, and decreasing the aggressiveness of the drill bit without sacrificing its efficiency. The rolling DOCC elements described herein may also reduce friction at the interface between the drill bit and the formation, and thereby allow for a steady depth of cut, which results in better tool face control. 
     In yet other example embodiments, the rolling element assemblies described herein may operate as a hybrid between a rolling cutting element and a rolling DOCC element. This may be accomplished by orienting the rotational axis of the rolling element on a plane that does not pass through the longitudinal axis of the drill bit nor is the plane oriented perpendicular to a plane that does pass through the longitudinal axis of the drill bit. Those skilled in the art will readily appreciate that the presently disclosed embodiments may improve upon hybrid rock bits, which use a large roller cone element as a depth of cut limiter by sacrificing diamond volume. In contrast, the presently disclosed rolling element assemblies are small in comparison and its enablement will not result in a significant loss of diamond volume on a fixed cutter drag bit. 
       FIG. 1A  is an isometric view of an example drill bit  100  that may employ the principles of the present disclosure. The drill bit  100  is depicted as a fixed cutter drill bit, and the present teachings may be applied to any fixed cutter drill bit category, including polycrystalline diamond compact (PDC) drill bits, drag bits, matrix drill bits, and/or steel body drill bits. While the drill bit  100  is depicted in  FIG. 1A  as a fixed cutter drill bit, the principles of the present disclosure are equally applicable to other types of drill bits operable to form a wellbore including, but not limited to, roller cone drill bits. 
     The drill bit  100  has a bit body  102  that includes radially and longitudinally extending blades  104  having leading faces  106 . The bit body  102  may be made of steel or a matrix of a harder material, such as tungsten carbide. The bit body  102  rotates about a longitudinal drill bit axis  107  to drill into underlying subterranean formation under an applied weight-on-bit. Corresponding junk slots  112  are defined between circumferentially adjacent blades  104 , and a plurality of nozzles or ports  114  can be arranged within the junk slots  112  for ejecting drilling fluid that cools the drill bit  100  and otherwise flushes away cuttings and debris generated while drilling. 
     The bit body  102  further includes a plurality of cutters  116  secured within a corresponding plurality of cutter pockets sized and shaped to receive the cutters  116 . Each cutter  116  in this example comprises a fixed cutter secured within its corresponding cutter pocket via brazing, threading, shrink-fitting, press-fitting, snap rings, or any combination thereof. The fixed cutters  116  are held in the blades  104  and respective cutter pockets at predetermined angular orientations and radial locations to present the fixed cutters  116  with a desired back rake angle against the formation being penetrated. As the drill string is rotated, the fixed cutters  116  are driven through the rock by the combined forces of the weight-on-bit and the torque experienced at the drill bit  100 . During drilling, the fixed cutters  116  may experience a variety of forces, such as drag forces, axial forces, reactive moment forces, or the like, due to the interaction with the underlying formation being drilled as the drill bit  100  rotates. 
     Each fixed cutter  116  may include a generally cylindrical substrate made of an extremely hard material, such as tungsten carbide, and a cutting face secured to the substrate. The cutting face may include one or more layers of an ultra-hard material, such as polycrystalline diamond, polycrystalline cubic boron nitride, impregnated diamond, etc., which generally forms a cutting edge and the working surface for each fixed cutter  116 . The working surface is typically flat or planar, but may also exhibit a curved exposed surface that meets the side surface at a cutting edge. 
     Generally, each fixed cutter  116  may be manufactured using tungsten carbide as the substrate. While a cylindrical tungsten carbide “blank” can be used as the substrate, which is sufficiently long to act as a mounting stud for the cutting face, the substrate may equally comprise an intermediate layer bonded at another interface to another metallic mounting stud. To form the cutting face, the substrate may be placed adjacent a layer of ultra-hard material particles, such as diamond or cubic boron nitride particles, and the combination is subjected to high temperature at a pressure where the ultra-hard material particles are thermodynamically stable. This results in recrystallization and formation of a polycrystalline ultra-hard material layer, such as a polycrystalline diamond or polycrystalline cubic boron nitride layer, directly onto the upper surface of the substrate. When using polycrystalline diamond as the ultra-hard material, the fixed cutter  116  may be referred to as a polycrystalline diamond compact cutter or a “PDC cutter,” and drill bits made using such PDC fixed cutters  116  are generally known as PDC bits. 
     As illustrated, the drill bit  100  may further include a plurality of rolling element assemblies  118 , shown as rolling element assemblies  118   a  and  118   b . The orientation of a rotational axis of each rolling element assembly  118   a,b  with respect to a tangent to an outer surface of the blade  104  may dictate whether the particular rolling element assembly  118   a,b  operates as a rolling DOCC element, a rolling cutting element, or a hybrid of both. As mentioned above, rolling DOCC elements may prove advantageous in allowing for additional weight-on-bit (WOB) to enhance directional drilling applications without over engagement of the fixed cutters  116 . Effective DOCC also limits fluctuations in torque and minimizes stick-slip, which can cause damage to the fixed cutters  116 . 
       FIG. 1B  is an enlarged portion of the drill bit  100  indicated by the dashed box shown in  FIG. 1A . As shown in  FIG. 1B , each rolling element assembly  118   a,b  is located in the blade  104  and includes a rolling element  122 . Exposed portions of the rolling elements  122  are illustrated in solid linetype, while portions of the rolling elements  122  that are seated within corresponding housings of the rolling element assemblies  118   a,b  are illustrated in dashed linetype. Each rolling element  122  has a rotational axis A, a Z-axis that is perpendicular to the blade profile  138  ( FIG. 1D ), and a Y-axis that is orthogonal to both the rotational and Z axes. 
     If, for example, the rotational axis A of the rolling element  122  is substantially parallel to a tangent to the outer surface  119  of the blade profile, the rolling element assembly  118   a,b  may generally operate as a rolling DOCC element. Said differently, if the rotational axis A of the rolling element  122  passes through or lies on a plane that passes through the longitudinal axis  107  ( FIG. 1A ) of the drill bit  100  ( FIG. 1A ), then the rolling element assembly  118   a,b  may substantially operate as a rolling DOCC element. If, however, the rotational axis A of the rolling element  122  is substantially perpendicular to the leading face  106  of the blade  104 , then the rolling element assembly  118   a,b  may substantially operate as a rolling cutting element. Thus, if the rotational axis A of the rolling element  122  is perpendicular to or lies on a plane that is perpendicular to a plane passing through the longitudinal axis  107  ( FIG. 1A ) of the drill bit  100  ( FIG. 1A ), then the rolling element assembly  118   a,b  may substantially operate as a rolling cutting element. 
     Accordingly, as depicted in  FIG. 1B , the first rolling element assembly  118   a  may be positioned to operate as a rolling cutting element and the second rolling element assembly  118   b  may be positioned to operate as a rolling DOCC element. In embodiments where the rotational axis A of the rolling element  122  lies on a plane that does not pass through the longitudinal axis  107  ( FIG. 1A ) of the drill bit  100  ( FIG. 1A ) nor is the plane perpendicular to the longitudinal axis  107 , the rolling element assembly  118   a,b  may then operate as a hybrid rolling DOCC and cutting element. 
     Traditional load-bearing type cutting elements for DOCC unfavorably affect torque-on-bit (TOB) by simply dragging, sliding, etc. along the formation, whereas a rolling DOCC element, such as the presently described rolling element assemblies  118   b , may reduce the amount of torque needed to drill a formation because it rolls to reduce friction losses typical with load bearing DOCC elements. The rolling DOCC elements described herein may also prove advantageous in reducing torque fluctuations and minimizing the occurrence of stick-slip. A rolling DOCC element will also have reduced wear as compared to a traditional bearing element. As will be appreciated, however, one or more of the rolling element assemblies  118   b  can also be used as rolling cutting elements, which may increase cutter effectiveness since it will distribute heat more evenly over the entire cutting edge and minimize the formation of localized wear flats on the rolling cutting element. 
       FIG. 1C  is a drawing in section and in elevation with portions broken away showing the drill bit  100  drilling a wellbore through a first downhole formation  124  and into an underlying second downhole formation  126 . The first downhole formation  124  may be described as softer or less hard when compared to the second downhole formation  126 . Exterior portions of the drill bit  100  that contact adjacent portions of the first and/or second downhole formations  124 ,  126  may be described as a bit face, and are projected rotationally onto a radial plane to provide a bit face profile  128 . The bit face profile  128  of the drill bit  100  may include various zones or segments and may be substantially symmetric about the longitudinal axis  107  of the drill bit  100  due to the rotational projection of the bit face profile  128 , such that the zones or segments on one side of the longitudinal axis  107  may be substantially similar to the zones or segments on the opposite side of the longitudinal axis  107 . 
     For example, the bit face profile  128  may include a first gage zone  130   a  located opposite a second gage zone  130   b , a first shoulder zone  132   a  located opposite a second shoulder zone  132   b , a first nose zone  134   a  located opposite a second nose zone  134   b , and a first cone zone  136   a  located opposite a second cone zone  136   b . The fixed cutters  116  included in each zone may be referred to as cutting elements of that zone. For example, the fixed cutters  116   a  included in gage zones  130   a,b  may be referred to as gage cutting elements, the fixed cutters  116   b  included in shoulder zones  132   a,b  may be referred to as shoulder cutting elements, the fixed cutters  116   c  included in nose zones  134   a,b  may be referred to as nose cutting elements, and the fixed cutters  116   d  included in cone zones  136   a,b  may be referred to as cone cutting elements. 
     Cone zones  136   a,b  may be generally concave and may be formed on exterior portions of each blade  104  ( FIG. 1A ) of the drill bit  100 , adjacent to and extending out from the longitudinal axis  107 . The nose zones  134   a,b  may be generally convex and may be formed on exterior portions of each blade  104 , adjacent to and extending from each cone zone  136 . Shoulder zones  132   a,b  may be formed on exterior portions of each blade  104  extending from respective nose zones  134   a,b  and may terminate proximate to a respective gage zone  130   a,b . The area of the bit face profile  128  may depend on cross-sectional areas associated with zones or segments of the bit face profile  128  rather than on a total number of fixed cutters  116 , a total number of blades  104 , or cutting areas per fixed cutter  116 . 
       FIG. 1D  illustrates a blade profile  138  that represents a cross-sectional view of one of the blades  104  of the drill bit  100  ( FIG. 1A ). The blade profile  138  includes the cone zone  136 , the nose zone  134 , the shoulder zone  132  and the gage zone  130 , as described above with respect to  FIG. 1C . Each zone  130 ,  132 ,  134 ,  135  may be based on its respective location along the blade  104  with respect to the longitudinal axis  107  and a horizontal reference line  140  that indicates a distance from the longitudinal axis  107  in a plane perpendicular to the longitudinal axis  107 . A comparison of  FIGS. 1C and 1D  shows that the blade profile  138  of  FIG. 1D  is upside down with respect to the bit face profile  128  of  FIG. 1C . 
     The blade profile  138  includes an inner zone  142  and an outer zone  144 . The inner zone  142  extends outward from the longitudinal axis  107  to a nose point  146 , and the outer zone  144  extends from the nose point  146  to the end of the blade  104 . The nose point  146  may be a location on the blade profile  138  within the nose zone  134  that has maximum elevation as measured by the bit longitudinal axis  107  (vertical axis) from reference line  140  (horizontal axis). A coordinate on the graph in  FIG. 1D  corresponding to the longitudinal axis  107  may be referred to as an axial coordinate or position. A coordinate corresponding to reference line  140  may be referred to as a radial coordinate or radial position that indicates a distance extending orthogonally from the longitudinal axis  107  in a radial plane passing through longitudinal axis  107 . For example, in  FIG. 1D , the longitudinal axis  107  may be placed along a Z-axis and the reference line  140  may indicate the distance (R) extending orthogonally from the longitudinal axis  107  to a point on a radial plane that may be defined as the Z-R plane. 
     Depending on how the rotational axis A ( FIG. 1B ) of each rolling element assembly  118   a,b  ( FIG. 1B ) is oriented with respect to the longitudinal axis  107 , and, more particularly with respect to the Z-R plane that passes through the longitudinal axis  107 , the rolling assemblies  118   a,b  may operate as a rolling DOCC element, a rolling cutting element, or a hybrid thereof. The rolling element assembly  118   a,b  will generally operate as a rolling DOCC element if the rotational axis A of the rolling element  122  lies on the Z-R plane, but will generally operate as a rolling cutting element if the rotational axis A of the rolling element  122  lies on a plane perpendicular to the Z-R plane. The rolling element assembly  118   a,b  may operate as a hybrid rolling DOCC element and a rolling cutting element in embodiments where the rotational axis A of the rolling element  122  lies on a plane offset from the Z-R plane, but not perpendicular thereto. 
     Depending on how they are oriented with respect to the longitudinal axis  107 , each rolling element assembly  118   a,b  ( FIG. 1B ) may exhibit side rake or back rake during operation. Side rake can be defined as the angle between the rotational axis A ( FIG. 1B ) of the rolling element  122  and the Z-R plane that extends through the longitudinal axis  107 . When the rotational axis A is parallel to the Z-R plane, the side rake is substantially 0°, such as in the case of the second rolling element assembly  118   b  of  FIG. 1B . When the rotational axis A is perpendicular to the Z-R plane, however, the side rake is substantially 90°, such as in the case of the first rolling element assembly  118   a  of  FIG. 1B . When viewed along the Z-axis from the positive Z-direction (viewing toward the negative Z-direction), a negative side rake results from counterclockwise rotation of the rolling element  122 , and a positive side rake results from clockwise rotation of the rolling element  122 . Said differently, when viewing from the top of the blade profile  128 , a negative side rake results from counterclockwise rotation of the rolling element  122 , and a positive side rake results from clockwise rotation of the rolling element  122  about the Z-axis. 
     Back rake can be defined as the angle subtended between the Z-axis of a given rolling element  122  and the Z-R plane. More particularly, as the Z-axis of a given rolling element  122  rotates offset backward or forward from the Z-R plane, the amount of offset rotation is equivalent to the measured back rake. If, however, the Z-axis of a given rolling element  122  lies on the Z-R plane, the back rake for that rolling element  122  will be 0°. 
     In some embodiments, one or more of the rolling element assemblies  118   a,b  may exhibit a side rake that ranges between 0° and 45° (or 0° and −45°), or alternatively a side rake that ranges between 45° and 90° (or −45° and −90°). In other embodiments, one or more of the rolling element assemblies  118   a,b  may exhibit a back rake that ranges between 0° and 45° (or 0° and −45°). The selected side rake will affect the amount of rolling versus the amount of sliding that a rolling element  122  included with the rolling element assembly  118   a,b  will undergo, whereas the selected back rake will affect how a cutting edge of the rolling element  122  engages the formation (e.g., the first and second formations  124 ,  126  of  FIG. 1C ) to cut, scrape, gouge, or otherwise remove material. 
     Referring again to  FIG. 1A , the second rolling element assemblies  118   b  may be placed in the cone region of the drill bit  100  and otherwise positioned so that rolling element assemblies  118   b  track in the path of the adjacent fixed cutters  116 ; e.g., they are placed in a secondary row behind the primary row of fixed cutters  116  on the blade  104 . However, since the second rolling element assemblies  118   b  are able to roll, they can be placed in positions other than the cone without affecting TOB. 
     Strategic placement of the first and second rolling element assemblies  118   a,b  may further allow them to be used as either primary and/or secondary rolling cutting elements as well as rolling DOCC elements, without departing from the scope of the disclosure. For instance, in some embodiments, one or more of the rolling element assemblies  118   a,b  may be located in a kerf forming region  120  located between adjacent fixed cutters  116 . During operation, the kerf forming region  120  results in the formation of kerfs on the underlying formation being drilled. One or more of the rolling element assemblies  118   a,b  may be located on the bit body  102  such that they will engage and otherwise extend across one or multiple formed kerfs during drilling operations. In such an embodiment, the rolling element assemblies  118   a,b  may also function as prefracture elements that roll on top of or otherwise crush the kerf(s) formed on the underlying formation between adjacent fixed cutters  116 . In other cases, one or more of the rolling element assemblies  118   a,b  may be positioned on the bit body  102  such that they will proceed between adjacent formed kerfs during drilling operations. In yet other embodiments, one or more of the rolling element assemblies  118   a,b  may be located at or adjacent the apex of the drill bit  100  (i.e., at or near the longitudinal axis  107 ). In such embodiments, the drill bit  100  may fracture the underlying formation more efficiently. 
     In some embodiments, as illustrated, the rolling element assemblies  118   a,b  may each be positioned on a respective blade  104  such that the rolling element assemblies  118   a,b  extend orthogonally from the outer surface  119  ( FIG. 1B ) of the respective blade  104 . In other embodiments, however, one or more of the rolling element assemblies  118   a,b  may be positioned at a predetermined angular orientation (three degrees of freedom) offset from normal to the profile of the outer surface  119  of the respective blade  104 . As a result, the rolling element assemblies  118   a,b  may exhibit an altered or desired back rake angle, side rake angle, or a combination of both. As will be appreciated, the desired back rake and side rake angles may be adjusted and otherwise optimized with respect to the primary fixed cutters  116  and/or the surface  119  ( FIG. 1B ) of the blade  104  on which the rolling element assemblies  118   a,b  are disposed. 
       FIG. 2  is a partial cross-sectional, isometric view of one example of a rolling element assembly  200 , according to one or more embodiments. The rolling element assembly  200  may be used, for example, with the drill bit  100  of  FIGS. 1A-1B , in which case the rolling element assembly  200  may be a substitution for either of the rolling element assemblies  118   a,b  or a specific example embodiment of the rolling element assemblies  118   a,b.    
     As illustrated, the rolling element assembly  200  may be positioned within a cavity  202  defined in a blade  104  of the drill bit  100  ( FIG. 1A ). Only a portion of the blade  104  is represented in  FIG. 2  and depicted in the general shape of a rectangular cube in cross-section. In embodiments where the drill bit  100  is made of a matrix material, the cavity  202  may be formed by selectively placing displacement materials (i.e., consolidated sand or graphite) at the location where the cavity  202  is to be formed. In embodiments where the drill bit  100  comprises a steel body drill bit, conventional machining techniques may be employed to machine the cavity  202  to desired dimensions at the desired location. Moreover, while the cavity  202  is shown as being defined in the blade  104 , it will be appreciated that the principles of the present disclosure are equally applicable to the cavity  202  being defined and otherwise provided at other locations of the drill bit  100 , without departing from the scope of the disclosure. 
     The rolling element assembly  200  includes a rolling element  204  that comprises a generally cylindrical or disk-shaped body having a first axial end  206   a  and a second axial end  206   b  opposite the first axial end  206   a . The distance between the first and second axial ends  206   a,b  is referred to herein as the axial width  208  of the rolling element  204 . 
     The rolling element  204  includes a substrate  210  and opposing diamond tables  212   a  and  212   b  arranged at the first and second axial ends  206   a,b , respectively, and otherwise coupled to opposing axial ends of the substrate  210 . The substrate  210  may be formed of a variety of hard or ultra-hard materials including, but not limited to, steel, steel alloys, tungsten carbide, cemented carbide, any derivatives thereof, and any combinations thereof. Suitable cemented carbides may contain varying proportions of titanium carbide (TiC), tantalum carbide (TaC), and niobium carbide (NbC). Additionally, various binding metals may be included in the substrate  210 , such as cobalt, nickel, iron, metal alloys, or mixtures thereof. In the substrate  210 , the metal carbide grains are supported within a metallic binder, such as cobalt. In other cases, the substrate  210  may be formed of a sintered tungsten carbide composite structure or a diamond ultra-hard material, such as polycrystalline diamond (PCD) or thermally stable polycrystalline diamond (TSP). 
     The diamond tables  212   a,b  may be made of a variety of ultra-hard materials including, but not limited to, polycrystalline diamond (PCD), thermally stable polycrystalline diamond (TSP), cubic boron nitride, impregnated diamond, nanocrystalline diamond, ultra-nanocrystalline diamond, and zirconia. Such materials are extremely wear-resistant and are suitable for use as bearing surfaces, as herein described. 
     The rolling element  204  may comprise and otherwise include one or more cylindrical bearing portions. More particularly, in this example, the entire rolling element  204  is cylindrical and made of hard, wear-resistant materials, and thus any portion of the rolling element  204  may be considered as a cylindrical bearing portion to the extent it slidingly engages a bearing surface of the cavity  202  or another component of the rolling element assembly  200  while rolling, such as would be expected during drilling operations. In some embodiments, for instance, one or both of the diamond tables  212   a,b  may be considered cylindrical bearing portions for the rolling element  204  and contact adjacent sidewalls of the cavity  202  during operation. In other embodiments, one or both of the diamond tables  212   a,b  may be omitted from the rolling element  204  and the substrate  210  may alternatively be considered as a cylindrical bearing portion. In yet other embodiments, the entire cylindrical or disk-shaped rolling element  204  may be considered as a cylindrical bearing portion and may be made of any of the hard or ultra-hard materials mentioned herein, without departing from the scope of the disclosure. 
     It should be noted that the features of the rolling element  204  are shown for illustrative purposes only and may or may not be drawn to scale. Consequently, the rolling element  204  as depicted should not be considered as limiting the scope of the present disclosure. For example, the thickness or axial extent (length) of the diamond tables  212   a,b  may or may not be the same. In at least one embodiment, for instance, one of the diamond tables  212   a,b  may be thicker than the other. Moreover, in some embodiments, one of the diamond tables  212   a,b  may be omitted from the rolling element  204  altogether. In yet other embodiments, the substrate  210  may be omitted and the rolling element  204  may instead be made entirely of the material of the diamond tables  212   a,b.    
     The rolling element assembly  200  also includes a compliant retainer  214  used to help secure or retain the rolling element  204  in the cavity  202  during use. The cavity  202  provides and otherwise defines an opening  216  large enough to receive the rolling element  204 ; i.e., the length of the opening  216  is larger than the diameter of the rolling element  204 . When seated within the cavity  202 , an arcuate portion of the rolling element  204  extends out of cavity  202  at the opening  216 , which exposes the full axial width  208  of the rolling element  204 . As will be described in greater detail below, a biasing device  218  may be included to act on and urge the compliant retainer  214  against the outer circumference of the rolling element  204  and thereby retain the rolling element  204  within the cavity  202  during operation. This is accomplished as portions of the cavity  202  and the compliant retainer  214  jointly encircle more than 180° of the circumference of the rolling element  204 , but less than 360°, so that the full axial width  208  of the rolling element  204  remains exposed for external contact with a formation during operation. 
     The compliant retainer  214  may exhibit a variety of cross-sectional shapes. In the illustrated embodiment, for example, the compliant retainer  214  is depicted as exhibiting a generally rectangular cross-section with two rounded (arced) sides. In other embodiments, however, the cross-section of the compliant retainer  214  may be circular, oval, ovoid, or any other polygonal shape, without departing from the scope of the disclosure. 
     In at least one embodiment, as illustrated, the rolling element assembly  200  may further include a bearing element  220  also positioned within the cavity  202  and engageable with the outer circumference of the rolling element  204 . Similar to the compliant retainer  214 , the bearing element  220  may exhibit a variety of cross-sectional shapes including, but not limited to, polygonal (e.g., rectangular, square, etc.), circular, oval, ovoid, or any combination thereof. In other embodiments, however, the bearing element  220  may be omitted, without departing from the scope of the disclosure. In such embodiments, the rolling element  204  may instead engage an inner arcuate surface or wall of the cavity  202 . 
     During drilling operations, the rolling element  204  is able to rotate within the cavity  202  about a rotational axis A of the rolling element  204 . As the rolling element  204  rotates about the rotational axis A, the compliant retainer  214  maintains the rolling element  204  within the cavity while allowing an arcuate portion to extend out of the cavity  202  through the opening  216  to engage (i.e., cut, roll against, or both) the underlying formation. This allows the full axial width  208  of the rolling element  204  across the entire outer circumferential surface to be progressively used as the rolling element  204  rotates during use. 
       FIG. 3  is a partial cross-sectional side view of the rolling element assembly  200  as installed within the cavity  202  defined in the blade  104 . As illustrated, the blade  104  (e.g., the bit body  102  of  FIG. 1A ) may provide or otherwise define a retainer slot  302  extending from and communicating with the volume of the cavity  202  and configured to receive and accommodate the compliant retainer  214 . Moreover, in embodiments where the bearing element  220  is included in the rolling element assembly  200 , the blade  104  (e.g., the bit body  102  of  FIG. 1A ) may further provide or otherwise define a bearing slot  304  extending from and communicating with the volume of the cavity  202  and configured to receive and accommodate the bearing element  220 . The retainer and bearing slots  302 ,  304  may exhibit a shape generally configured to receive the cross-sectional shape of the compliant retainer  214  and the bearing element  220 , respectively. 
     The compliant retainer  214  provides an inner arcuate surface  306  and a back surface  308  opposite the inner arcuate surface  306 . With the compliant retainer  214  received within the retainer slot  302 , the back surface  308  will be disposed against or otherwise adjacent a bottom  310  of the retainer slot  302  and the inner arcuate surface  306  will be disposed against or otherwise adjacent the outer circumferential surface of the rolling element  204 . Similarly, the bearing element  220  provides an inner arcuate surface  312  and a back surface  314  opposite the inner arcuate surface  306 . With the bearing element  220  received within the bearing slot  304 , the back surface  314  will be disposed against or otherwise adjacent a bottom  316  of the bearing slot  304  and the inner arcuate surface  312  will be disposed against or otherwise adjacent the outer circumferential surface of the rolling element  204 . The curvature of the inner arcuate surfaces  306 ,  312  and the interposing inner wall of the cavity  202  (if any) enables the rolling element  204  to bear against a continuously (uniformly) curved surface at all angular locations within the cavity  202  during operation. 
     The compliant retainer  214  and the bearing element  220  (if used) can be made of any of the hard or ultra-hard materials mentioned above for the substrate  212  and the diamond tables  214   a,b . More specifically, the compliant retainer  214  and/or the bearing element  220  may be of materials such as, but not limited to, steel, a steel alloy, tungsten carbide, a sintered tungsten carbide composite structure, cemented carbide, polycrystalline diamond (PCD), thermally stable polycrystalline diamond (TSP), cubic boron nitride, impregnated diamond, nanocrystalline diamond, ultra-nanocrystalline diamond, zirconia, any derivatives thereof, and any combinations thereof. Alternatively, or in addition thereto, the compliant retainer  214  and/or the bearing element  220  may be made of an engineering metal, a coated material (i.e., using processes such as chemical vapor deposition, plasma vapor deposition, etc.), or other hard or abrasion-resistant materials. 
     The biasing device  218  may be positioned within a device pocket  318  defined within the blade  104  (e.g., the bit body  102  of  FIG. 1A ) and extending from and otherwise communicating with the retainer slot  302 . In some embodiments, as illustrated, the biasing device  218  comprises a helical compression spring. In other embodiments, however, the biasing device  318  may comprise any other device or means capable of biasing the compliant retainer  214  into engagement with the outer circumference of the rolling element  204 . For example, the biasing device  318  may alternatively comprise a series of Belleville washers, an air shock, a hydraulic shock, an engineered polymer, a plastic, an elastic material, or any combination of the foregoing. 
     In the illustrated embodiment, the biasing device  218  is positioned between and otherwise engageable with the back surface  308  of the compliant retainer  214  and a bottom  320  of the device pocket  318 . When the rolling element assembly  200  is properly assembled, the biasing device  218  acts on and urges the compliant retainer  214  against the outer circumference of the rolling element  204 , which moves the compliant retainer  214  off the bottom  310  of the retainer slot  302 . As a result, a gap  322  can form between the back surface  308  of the compliant retainer  214  and the bottom  310 . Formation of the gap  322  allows the rolling element  204  to be properly retained within the cavity  202  for operation and also facilitates an amount of give that the rolling element assembly  200  may assume during operation, which may prove advantageous in extending the service life of the rolling element  204 . 
     The rolling element assembly  200  may be assembled by first inserting the biasing device  218  into the device pocket  318  and subsequently inserting the compliant retainer  214  into the retainer slot  302 , and thereby engaging the back surface  308  of the compliant retainer  214  against the biasing device  218 . As biased by the biasing device  218 , the compliant retainer  214  extends partially into the volume of the cavity  202  and the gap  322  will be at its largest. If included in the rolling element assembly  200 , the bearing element  220  may also be inserted into the bearing slot  304 . The rolling element  204  may then be inserted into the cavity  202  via the opening  216 . As the rolling element  204  extends into the cavity  202 , it engages an upper extent  324  of the compliant retainer  214 , which forms part of the inner arcuate surface  306 . Engaging the upper extent  324  pushes (urges) the compliant retainer  214  deeper into the retainer slot  302  and thereby decreases the magnitude of the gap  322  and simultaneously compresses the biasing device  218 , which builds spring (biasing) force. Once the diameter of the rolling element  204  traverses (surpasses) the upper extent  324 , the spring force is able to at least partially release and the biasing device  218  urges the compliant element  214  against the rolling element  204  and the inner arcuate surface  306  is brought into engagement with the outer circumference of the rolling element  204 . 
     As biased against the outer circumference of the rolling element  204 , the compliant element  214  serves to retain the rolling element  204  within the cavity  202 . More specifically, when the rolling element  204  is assembled in the cavity  202 , the rolling element  204  exhibits a centerline  326  that is generally parallel with (or tangent to) the opening  216  and perpendicular to the rotational axis A. Since the upper extent  324  of the compliant retainer  214  extends above the centerline  326 , more than 180° (but less than 360°) of the circumference of the rolling element  204  will be engaged with and otherwise encircled by the compliant retainer  214 , portions of the inner arcuate walls of the cavity  202 , and/or the bearing element  220  (if used). Moreover, the cavity  202  is sized such that the rolling element  204  bottoms out with an arcuate portion extending out of the opening  216  so that the full axial width  208  ( FIG. 2 ) of the rolling element  204  remains exposed for external contact with a formation during operation. 
     In some applications, the rolling element assembly  200  may be arranged on the blade  104  such that the rolling element  204  will rotate about the rotational axis A in a first direction  330  during operation. As the rolling element  204  engages an underlying subterranean formation and rotates about the rotational axis A, a weight on bit (WOB) force F 1  and a friction force F 2  will act on the rolling element  204 . The WOB force F 1  is the weight force applied to the rolling element  204  in the direction of advancement of the drill bit  100  ( FIGS. 1A-1B ). The friction force F 2  is a drag force assumed by the rolling element  204  and applied in the direction opposite rotation of the drill bit  100 . Based on the respective magnitudes of the WOB force F 1  and the friction force F 2 , a resultant force F R  will be assumed by the rolling element  204 . The magnitude of the resultant force F R  may be determined as follows:
 
F R   2 F 1   2 +F 2   2   Equation (1)
 
     and the resultant force F R  vector will be directed at an angle θ offset from the WOB force F 1 . The angle θ may be determined as follows: F R   
     
       
         
           
             
               
                 
                   θ 
                   = 
                   
                     arctan 
                     ⁢ 
                     
                       
                         F 
                         R 
                       
                       
                         F 
                         1 
                       
                     
                   
                 
               
               
                 
                   Equation 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   
                     ( 
                     2 
                     ) 
                   
                 
               
             
           
         
       
     
     If the direction of the resultant force F R  vector intersects the compliant retainer  214  as positioned within the retainer slot  302 , then the compliant retainer  214  may not only be used to help retain the rolling element  204  in the cavity  202 , but may also prove useful as a bearing element that assumes at least a portion of the resultant force F R  of the rolling element  204  during drilling operations. In such embodiments, the biasing device  218  may prove advantageous in assuming shock or impact loads during operation, which would abruptly decrease the magnitude of the gap  322 . If, however, the direction of the resultant force F R  vector does not intersect the compliant retainer  214 , then the compliant retainer  214  will primarily serve as a structure that helps retain the rolling element  204  in the cavity  202 . 
     In the illustrated embodiment, an arc length L of the compliant retainer  214  is long enough such that the resultant force F R  vector will intersect the compliant retainer  214 , which allows the compliant retainer  214  to simultaneously operate as a retaining structure and a bearing element. In other embodiments, however, and depending on known or predicted drilling parameters, the arc length L of the compliant retainer  214  may be increased or decreased to allow the compliant retainer  214  to operate solely as a retainer. Accordingly, the compliant retainer  214  not only helps secure the rolling element  204  in the cavity  202 , but can also serve as a bearing surface that supports and guides the rolling element  204 . 
     Alternatively, the friction force F 2  may be applied on the rolling element  204  in a direction opposite to that which is shown in  FIG. 3 . In such embodiments, the resultant force F R  would be instead directed generally at the bearing element  220 , which would assume most (if not all) of the impact loading during operation. The compliant retainer  214  would then serve the primary purpose of retaining the rolling element  204  within the cavity  202 . The biasing device  218  may be configured and otherwise designed to provide sufficient biasing force to maintain constant contact between the compliant retainer  214  and the rolling element  204 . 
     Given the design of the rolling element assembly  200 , the force exerted on the compliant retainer  214  or the bearing element  220  during operation will be primarily compressive in nature. Having the compliant retainer  214  and the bearing element  220  made of a hard or ultra-hard material may help reduce the amount of friction and wear between the rolling element  204  and the inner arcuate surfaces  306 ,  312  as the rolling element  204  bears and slides against the inner arcuate surfaces  306 ,  312 . Consequently, the hard or ultra-hard materials of the compliant retainer  214  and the bearing element  220  may reduce or eliminate the need for lubrication between the rolling element  204  and the inner arcuate surfaces  306 ,  312  of the compliant retainer  214  and the bearing element  220 , respectively. In at least one embodiment, however, one or both of the inner arcuate surfaces  306 ,  312  may be polished so as to reduce friction between the opposing surfaces. The inner arcuate surfaces  306 ,  312  may be polished, for example, to a surface finish of about 40 micro-inches or better. 
     It should be noted that, although the rolling element assembly  200  has been described as retaining one rolling element  204 , embodiments of the disclosure are not limited thereto and the rolling element assembly  200  (or any of the rolling element assemblies described herein) may include and otherwise use two or more rolling elements  204 , without departing from the scope of the disclosure. In such embodiments, the multiple rolling elements  204  may be retained within the cavity  202  using the compliant retainer  214  or each rolling element  204  may be supported by individual compliant retainers  214 . 
       FIG. 4  is a partial cross-sectional side view of another embodiment of the rolling element assembly  200  as installed within the cavity  202  defined in the blade  104 . Unlike the embodiment of  FIG. 3 , the bearing element  220  ( FIG. 3 ) is omitted from the embodiment of  FIG. 4 . As illustrated, the compliant retainer  214  is arranged within the retainer slot  302  and maintains the rolling element  204  within the cavity  202 . The biasing device  218  acts on and urges the compliant retainer  214  against the outer circumference of the rolling element  204 . Assembly of the embodiment of  FIG. 4  is similar to the assembly of the embodiment of  FIG. 3  and, therefore, will not be provided again. During operation, the resultant force F R  ( FIG. 3 ) may be directed toward and assumed by an inner arcuate surface  402  of the cavity  202 , thereby allowing the compliant retainer  214  to serve the primary purpose of retaining the rolling element  204  within the cavity  202 . 
       FIG. 5  is a partial cross-sectional side view of another embodiment of the rolling element assembly  200  as installed within the cavity  202  defined in the blade  104 . In the illustrated embodiment, a second biasing device  502  may be positioned within a second device pocket  504  defined within the blade  104  (e.g., the bit body  102  of  FIG. 1A ) and extending from and otherwise communicating with the bearing slot  304  that receives the bearing element  220 . Similar to the biasing device  218 , in some embodiments the second biasing device  502  may comprise a helical compression spring, as illustrated, but may alternatively comprise any other device or means capable of biasing the bearing element  220  into engagement with the outer circumference of the rolling element  204 . For example, the biasing device  318  may alternatively comprise a series of Belleville washers, an air shock, a hydraulic shock, an engineered polymer, a plastic, an elastic material, or any combination of the foregoing. 
     In the illustrated embodiment, the second biasing device  502  is positioned between and otherwise engageable with the back surface  314  of the bearing element  220  and a bottom  506  of the second device pocket  504 . When the rolling element assembly  200  is assembled within the cavity  202 , the second biasing device  502  acts on and urges the bearing element  220  against the outer circumference of the rolling element  204 . Similar to the operation of the biasing device  218 , the second biasing device  502  may also prove advantageous in assuming shock or impact loading from the rolling element  204  during operation, and thereby help extend the operational life of the rolling element assembly  200 . 
     In some embodiments, the retainer slot  302  may be defined in the blade  104  at a first angle  508   a  relative to the outer surface  328  of the blade  104 , and the bearing slot  304  may be defined in the blade  104  at a second angle  508   b  relative to the outer surface  328  of the blade  104  such that the retainer and bearing slots  302 ,  304  may be angularly offset from each other by a third angle  508   c . The angles  508   a,b  may be optimized depending on the type of drill bit being used and the projected rate of penetration. For example, the first angle  508   a  may dictate what geometry is suitable for the compliant retainer  204  to properly retain the rolling element  204  within the cavity  202 . More specifically, the first angle  508   a  may be optimized such that the upper extent  324  extends above the centerline  326  ( FIG. 3 ) of the rolling element  204  such that more than 180° (but less than 360°) of the circumference of the rolling element  204  will be encircled at any given moment to lock the rolling element  204  within the cavity  202 . Moreover, the second angle  508   b  may be optimized and otherwise configured such that the bearing element  220  lies substantially perpendicular to a projected load direction (e.g., the resultant force F R  of  FIG. 3 ) expected during drilling operations to enable the bearing element  220  to assume most (if not all) of the loading. 
       FIG. 6  is a partial cross-sectional, isometric view of another example of the rolling element assembly  200 , according to one or more embodiments. In the illustrated embodiment, a locking pin  602  may be included in the rolling element assembly  200  and used to secure the rolling element  204  within the cavity  202 . More particularly, the locking pin  602  may be insertable into (accommodated within) a body aperture  604  defined in the blade  104  and extending from the outer surface  328  of the blade  104 . The body aperture  604  extends to and penetrates the retainer slot  302 . In some embodiments, as illustrated, the body aperture  604  may extend past (through) the retainer slot  302  and deeper into the blade  104 , but may alternatively only penetrate the retainer slot  302 , without departing from the scope of the disclosure. 
     The compliant retainer  214  may provide and otherwise define a retainer aperture  606  alignable with the body aperture  604  when the compliant retainer  214  is arranged in the retainer slot  302 . The locking pin  602  is configured to be extended into the body aperture  604  and simultaneously into the aligned retainer aperture  606  to lock the compliant retainer  214  in place within the retainer slot  302 . This may prove advantageous in helping to secure the rolling element  204  within the cavity  202  since the compliant retainer  214  would be unable to move to a position in the retainer slot  302  where the rolling element  204  would be able to bypass the upper extent  324  for extraction from the cavity  202 . 
     In some embodiments, the locking pin  602  may be threaded into one or both of the blade and retainer apertures  604 ,  606 . In other embodiments, the locking pin  602  may simply be extended into the blade and retainer apertures  604 ,  606 . The locking pin  602  may exhibit a variety of cross-sectional shapes. In the illustrated embodiment, for example, the locking pin  602  is depicted as exhibiting a generally circular cross-section. In other embodiments, however, the cross-section of the compliant retainer  214  may be oval, ovoid, or polygonal, without departing from the scope of the disclosure. 
     In some embodiments, the retainer aperture  606  may be sized to allow the compliant retainer  214  a small amount of travel within the retainer slot  302 . More specifically, as illustrated, the retainer aperture  606  may be defined as an elongated oval that allows the compliant retainer  214  to translate a small distance within the retainer slot  302  as constrained by the geometry of the elongated oval. This may prove advantageous in allowing the compliant retainer  214  to exhibit an amount of give as biased against the biasing device  218  during operation. As a result, shock or impact loading assumed by the rolling element  204  may be transferred at least partially to the compliant retainer  214  and the biasing device  218 , which may extend the service life of the rolling element assembly  200 . 
       FIG. 7  is a partial cross-sectional side view of another embodiment of the rolling element assembly  200  as installed within the cavity  202  defined in the blade  104 . The illustrated embodiment is similar in some respects to the embodiment shown in  FIG. 4 . As illustrated, the compliant retainer  214  is arranged within the retainer slot  302  and the biasing device  218  acts on and urges the compliant retainer  214  against the outer circumference of the rolling element  204  to help maintain the rolling element  204  within the cavity  202 . 
     Unlike the embodiment of  FIG. 4 , however, the cavity  202  in the embodiment of  FIG. 7  includes a retention feature that also helps retain the rolling element  204  within the cavity. More specifically, the inner arcuate surface  402  of the cavity  202  opposite the retainer slot  302  may proceed in a continuous curved or arced trajectory until terminating at the opening  216 . As a result, the compliant retainer  214  and a portion of the inner arcuate surface  402  at the opening  216  jointly encircle more than 180° of the circumference of the rolling element  204 , but less than 360° and thereby retain the rolling element  204  within the cavity  202 . Although the inner arcuate surface  402  provides an elongated continuous curved or arced surface as compared to the embodiment of  FIG. 4 , the length of the opening  216  remains larger than the diameter of the rolling element  204  to allow the rolling element  204  to enter. 
     Embodiments disclosed herein include: 
     A. A rolling element assembly that includes a rolling element rotatable about a rotational axis when positioned within a cavity defined on a bit body of a drill bit, a compliant retainer positioned within a retainer slot defined in the bit body, and a biasing device positioned within a device pocket defined within the bit body to bias the compliant retainer against the outer circumferential surface of the rolling element, wherein the compliant retainer secures the rolling element within the cavity while an arcuate portion of the rolling element protrudes from the cavity and exposes a full axial width of the rolling element. 
     B. A drill bit that includes a bit body including one or more blades extending therefrom, a plurality of cutters secured to the one or more blades, and a rolling element assembly positioned within a cavity defined on the bit body, the rolling element assembly including a rolling element rotatable within the cavity about a rotational axis and a compliant retainer positioned within a retainer slot defined in the bit body and biased against an outer circumferential surface of the rolling element, wherein the compliant retainer secures the rolling element within the cavity while an arcuate portion of the rolling element protrudes from the cavity and exposes a full axial width of the rolling element. 
     Each of embodiments A and B may have one or more of the following additional elements in any combination: Element 1: wherein at least the compliant retainer and the cavity cooperatively encircle more than 180° but less than 360° of a circumference of the rolling element. Element 2: wherein the biasing device causes formation of a gap between a back surface of the compliant retainer and a bottom of the retainer slot. Element 3: wherein the compliant retainer comprises a material selected from the group consisting of steel, a steel alloy, tungsten carbide, a sintered tungsten carbide composite, cemented carbide, polycrystalline diamond, thermally stable polycrystalline diamond, cubic boron nitride, impregnated diamond, nanocrystalline diamond, ultra-nanocrystalline diamond, zirconia, any derivatives thereof, and any combination thereof. Element 4: wherein the compliant retainer defines an inner arcuate surface having an upper extent that extends above a centerline of the rolling element when the rolling element is assembled in the cavity. Element 5: further comprising a bearing element positioned within a bearing slot defined in the bit body and having an inner arcuate surface engageable with the outer circumference of the rolling element. Element 6: further comprising a second biasing device positioned within a second device pocket defined within the bit body to bias the bearing element against the outer circumferential surface of the rolling element. Element 7: further comprising a locking pin that secures the compliant retainer within the retainer slot. Element 8: wherein the bit body defines a body aperture that penetrates the retainer slot and the compliant retainer defines a retainer aperture alignable with the body aperture, and wherein the locking pin is extendable into the body aperture and the retainer aperture. Element 9: wherein the retainer aperture is sized to allow the compliant retainer to translate within the retainer slot. 
     Element 10: wherein the cavity is defined on the one or more blades. Element 11: wherein the compliant retainer defines an inner arcuate surface having an upper extent that extends above a centerline of the rolling element when the rolling element is assembled in the cavity. Element 12: further comprising a bearing element positioned within a bearing slot defined in the bit body and having an inner arcuate surface engageable with the outer circumference of the rolling element. Element 13: further comprising a second biasing device positioned within a second device pocket defined within the bit body to bias the bearing element against the outer circumferential surface of the rolling element. Element 14: further comprising a locking pin extendable through a body aperture defined in the bit body to secure the compliant retainer within the retainer slot. Element 15: wherein the rolling element assembly is oriented on the bit body to exhibit a side rake angle ranging between 0° and 45° or a side rake angle ranging between 45° and 90°. Element 16: wherein the rolling element assembly is oriented on the bit body to exhibit a back rake angle ranging between 0° and 45°, thereby allowing the rolling element to operate as a cutter. Element 17: wherein the rotational axis of the rolling element lies on a plane that passes through a longitudinal axis of the bit body. Element 18: wherein the rotational axis of the rolling element lies on a plane that is perpendicular to a longitudinal axis of the bit body. 
     By way of non-limiting example, exemplary combinations applicable to A and B include: Element 5 with Element 6; Element 7 with Element 8; Element 8 with Element 9; Element 12 with Element 13; 
     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.