Patent Publication Number: US-11021912-B2

Title: Rotary steering systems and methods

Description:
BACKGROUND 
     This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. 
     The present disclosure generally relates to a steering assembly for directionally drilling a borehole in an earth formation. Directional drilling is the intentional deviation of a borehole from the path it would naturally take, which may include the steering of a drill bit so that it travels in a predetermined direction. In many industries, it may be desirable to directionally drill a borehole through an earth formation in order to, for example, circumvent an obstacle and/or to reach a predetermined location in a rock formation. 
     In the oil and gas industry, boreholes are drilled into the earth to access natural resources (e.g., oil, natural gas, water) below the earth&#39;s surface. These boreholes may be drilled on dry land or in a subsea environment. In order to drill a borehole for a well, a rig is positioned proximate the natural resource. The rig suspends and powers a drill bit coupled to a drill string that drills a bore through one or more layers of sediment and/or rock. After accessing the resource, the drill string and drill bit are withdrawn from the well and production equipment is installed. The natural resource(s) may then flow to the surface and/or be pumped to the surface for shipment and further processing. 
     Directional drilling techniques have been developed to enable drilling of multiple wells from the same surface location with a single rig, and/or to extend wellbores laterally through their desired target formation(s) for improved resource recovery. Each borehole may change direction multiple times at different depths between the surface and the target reservoir by changing the drilling direction. The wells may access the same underground reservoir at different locations and/or different hydrocarbon reservoirs. For example, it may not be economical to access multiple small reservoirs with conventional drilling techniques because setting up and taking down a rig(s) can be time consuming and expensive. However, the ability to drill multiple wells from a single location and/or to drill wells with lateral sections within their target reservoir(s) may reduce cost and environmental impact. 
     SUMMARY 
     A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below. 
     The present disclosure relates generally to systems and methods for directionally drilling a borehole. In embodiments, a drilling system includes a drill bit that drills a bore through rock. A shaft is coupled to the drill bit, wherein the shaft transfers rotational power to the drill bit. A housing receives at least part of the shaft. A rotary steering system includes a steering sleeve that couples to and uncouples from the housing to control a drilling direction of the drill bit. In embodiments, a rotary steering system for controlling a drilling direction of a drill bit includes a steering sleeve that couples to and uncouples from a housing. A steering pad coupled to the steering sleeve rotates with the steering sleeve and forms a steering angle with the drill bit. 
     In other embodiments, a method of controlling a drilling direction of a drill bit may include disconnecting a steering sleeve from a housing, where the steering sleeve includes a steering pad that forms a steering angle with the drill bit. In embodiments, methods of the present disclosure may also actuate a piston to move radially with respect to a longitudinal axis of the steering sleeve to limit rotation of the steering pad. 
     Additional details regarding operations of the steering systems and methods of the present disclosure are provided below with reference to  FIGS. 1-9 . 
     Various refinements of the features noted above may be made in relation to various aspects of the present disclosure. Further features may also be incorporated in these various aspects as well. These refinements and additional features may be made individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. The brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of embodiments of the present disclosure without limitation to the claimed subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying figures in which like characters represent like parts throughout the figures, wherein: 
         FIG. 1  schematically illustrates a rig coupled to a plurality of wells for which the rotary steering systems and methods of the present disclosure can be employed to drill the boreholes; 
         FIG. 2  schematically illustrates an exemplary directional drilling system coupled to a rig according to an embodiment of the present disclosure; 
         FIG. 3  is a cross-sectional view of a directional drilling system with a rotary steering system according to an embodiment of the present disclosure; 
         FIG. 4  is a cross-sectional view of a directional drilling system with a rotary steering system according to an embodiment of the present disclosure; 
         FIG. 5  is a cross-sectional view of a directional drilling system with a rotary steering system according to an embodiment of the present disclosure; 
         FIG. 6  is a cross-sectional view of a directional drilling system with a rotary steering system according to an embodiment of the present disclosure; 
         FIG. 7  is a cross-sectional view of a directional drilling system with a rotary steering system according to an embodiment of the present disclosure; 
         FIG. 8  is a cross-sectional view of a directional drilling system with a rotary steering system according to an embodiment of the present disclosure; and 
         FIG. 9  is a cross-sectional view of a directional drilling system with a rotary steering system according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     One or more specific embodiments of the present disclosure will be described below. These described embodiments are only exemplary of the present disclosure. Additionally, in an effort to provide a concise description of these exemplary embodiments, all features of an actual implementation may not be described. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
     The drawing figures are not necessarily to scale. Certain features of the embodiments may be shown exaggerated in scale or in somewhat schematic form, and some details of conventional elements may not be shown in the interest of clarity and conciseness. Although one or more embodiments may be preferred, the embodiments disclosed should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims. It is to be fully recognized that the different teachings of the embodiments discussed may be employed separately or in any suitable combination to produce desired results. In addition, one skilled in the art will understand that the description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to intimate that the scope of the disclosure, including the claims, is limited to that embodiment. 
     When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “including” and “having” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” Any use of any form of the terms “couple,” “connect,” “attach,” “mount,” or any other term describing an interaction between elements is intended to mean either a direct or an indirect interaction between the elements described. Moreover, any use of “top,” “bottom,” “above,” “below,” “upper,” “lower,” “up,” “down,” “vertical,” “horizontal,” “left,” “right,” and variations of these terms is made for convenience but does not require any particular orientation of components. 
     Certain terms are used throughout the description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function, unless specifically stated. 
     The discussion below describes rotary steering systems and methods for controlling the orientation of a drill bit while directionally drilling a borehole. The steering assemblies of the present disclosure are disposed above the drill bit and include one or more over-gauge pads, where “over-gauge” refers to the pad having one or more points of extension greater than a nominal full-gauge or “gauge” as defined by a maximum drill bit cutter tip extension in a radial direction. Thus, for example, the radius of an over-gauge pad at a particular point is greater than the full-gauge radius of the drill bit in that radial direction. In embodiments, an over-gauge pad may include full-gauge and/or under-gauge area(s), where under-gauge refers to having one or more points of extension less than gauge as defined by a maximum drill bit cutter tip extension in that radial direction. Over-gauge pads will be referred to as “steering pads” below. 
     The maximum radial extension of a drill bit&#39;s cutter tips, and therefore the full-gauge radius, typically is (but need not be) substantially constant. A radius or gauge of a steering pad may or may not be substantially constant along its length in operation, i.e. at a given time, location, or degree of extension, as will be described further below. Moreover, at a given time, location, or degree of extension, steering pad radius may vary along its length and/or relative to a longitudinal axis of the drill string and/or on any plane perpendicular to the longitudinal axis. 
       FIG. 1  schematically illustrates an exemplary drill site  10  in which the systems and methods of the present disclosure can be employed. The drill site  10  may be located either offshore (as shown) or onshore, near one or multiple hydrocarbon-bearing rock formations or reservoirs  12  (e.g., for the production of oil and/or gas), or near one or more other subsurface earth zone(s) of interest. Using directional drilling and the rotary steering systems and methods presently described, a drilling rig  14  with its related equipment can drill multiple subsurface boreholes for wells  16  beginning from a single surface location for a vertical bore. Once completed. these wells  16  may fluidly connect to the same hydrocarbon reservoir  12  at different locations and/or to different reservoirs  12  in order to extract oil and/or natural gas. 
     As illustrated, each well  16  may define a different trajectory, including for example different degrees and/or lengths of curvature, in order to access and/or maximize surface area for production within the hydrocarbon reservoir(s)  12 . The trajectory of a well  16  may depend on a variety of factors, including for example the distance between target reservoir(s)  12  and the rig  14 , horizontal extension of a reservoir for hydrocarbon capture, as well as predicted and/or encountered rock stratigraphy, drilling obstacles, etc. between the surface and the subsurface drilling target(s). There may varying rock formation layers  18  between the rig  14  and a hydrocarbon reservoir  12 , with some of layers  18  easily and relatively quickly drilled through, and other layers  18  time consuming and subject to increased wear on drilling components. The optimal trajectory to access a hydrocarbon reservoir  12  therefore may not be the shortest distance between the rig  14  and the hydrocarbon reservoir  12 . 
     A drilling plan may be developed to include a trajectory for each proposed well  16  that takes into account properties (e.g., thicknesses, composition) of the layers  18 . Following the drilling plan, borehole(s) for the well(s)  16  may be drilled to avoid certain layers  18  and/or drill through thinner portions of difficult layers  18  using directional drilling and/or to extend a substantially horizontal section through a reservoir  12 . Directional drilling may therefore reduce drill time, reduce wear on drilling components, and fluidly connect the well  16  at or along a desired location in the reservoir  12 , among other factors. 
     In  FIG. 1 , the rig  14  is an offshore drilling rig using directional drilling to drill the wells  16  below a body of water. It should be understood that directional drilling may be done with onshore rigs as well. Moreover, while the wells  16  may be wells for oil and gas production from hydrocarbon-bearing reservoirs, directional drilling is and can be performed for a variety of purposes and with a variety of targets within and outside of the oil and gas industry, including without limitation in water, geothermal, mineral, and exploratory applications. Additionally, while  FIG. 1  illustrates multiple well  16  trajectories extending from one rig  14  surface location, the number of wells extending from the same or similar surface location may be one or otherwise may be more or less than shown. 
       FIG. 2  schematically illustrates an exemplary directional drilling system  30  coupled to a rig  14 . The directional drilling system  30  includes at bottom a drill bit  32  designed to break up rock and sediments into cuttings. The drill bit  32  couples to the rig  14  using a drill string  34 . The drill string  34  is formed with a series of conduits, pipes or tubes that couple together between the rig  14  and the drill bit  32 . In order to carry the cuttings away from the drill bit  32  during a drilling operation, drilling fluid, also referred to as drilling mud or mud, is pumped from surface through the drill string  34  and exits the drill bit  32 . The drilling mud then carries the cuttings away from the drill bit  32  and toward the surface through an annulus  35  between an inner wall of the borehole  37  formed by the drill bit  32  and an outer wall of the drill string  34 . By removing the cuttings from the borehole  37  for a well  16 , the drill bit  32  is able to progressively drill further into the earth. 
     In addition to carrying away the cuttings, the drilling mud may also power a hydraulic motor  36  also referred to as a mud motor. Drilling mud is pumped into the borehole  37  at high pressures in order to carry the cuttings away from the drill bit  32 , which may be at a significant lateral distance and/or vertical depth from the rig  14 . As the mud flows through the drill string  34 , it enters a hydraulic motor  36 . The flow of mud through the hydraulic motor  36  drives rotation of the hydraulic motor  36 , which in turn rotates a shaft coupled to the drill bit  32 . As the shaft rotates, the drill bit  32  rotates, enabling the drill bit  32  to cut through rock and sediment. In some embodiments, the hydraulic motor  36  may be replaced with an electric motor that provides power to rotate the drill bit  32 . In still other embodiments, the directional drilling system  30  may not include a hydraulic motor or electric motor on the drill string  34 . Instead, the drill bit  32  may rotate in response to rotation of the drill string  34  from at or near the rig  14 , for example by a top drive  38  on the rig  14 , or a kelly drive and rotary table, or by any other device or method that provides torque to and rotates the drill string  34 . 
     In order to control a drilling direction  39  of the drill bit  32 , the directional drilling system  30  may include a rotary steering system  40  of the present disclosure. As will be discussed in detail below, the rotary steering system  40  includes a steering sleeve with one or more steering pads oriented to change and control the drilling direction  39  of the drill bit  32 . The rotary steering system  40  may be controlled by an operator and/or autonomously using feedback from a measurement-while-drilling system  42 . The measurement-while-drilling system  42  uses one or more sensors to determine the well path or borehole drilling trajectory in three-dimensional space. The sensors in the measurement-while-drilling system  42  may provide measurements in real-time and/or may include accelerometers, gyroscopes, magnetometers, position sensors, flow rate sensors, temperature sensors, pressure sensors, vibration sensors, torque sensors, and/or the like, or any combination of them. 
       FIG. 3  is a cross-sectional view of an embodiment of a directional drilling system  30  with a rotary steering system  40  of the present disclosure. As explained above with reference to  FIG. 2 , the directional drilling system  30  includes at bottom a drill bit  32  capable of cutting through rock and/or sediment to drill a borehole for a well  16 . The drill bit  32  may be powered by a motor (e.g., hydraulic or mud motor, electric motor) that in operation transfers torque to the drill bit  32  through a drive shaft  60 . The drill bit  32  may couple to the drive shaft  60  with one or more bolts  62  enabling power transfer from the motor. As the drive shaft  60  rotates, torque drives rotation of the drill bit  32 , enabling cutters or teeth  64  (e.g., polycrystalline diamond teeth) to grind into the rock face  66 . As the teeth  64  grind against the rock face  66 , the rock face  66  breaks into pieces called cuttings. The cuttings are then carried away from the rock face  66  with drilling mud  68 . The drilling mud  68  flows through a conduit or passageway  70  in the drive shaft  60  and then through openings, nozzles or apertures  72  in the drill bit  32 , carrying the cuttings around the drill bit  32  and back through the recently drilled bore. 
     In order to steer the directional drilling system  30  and more specifically control the orientation of the drill bit  32 , the directional drilling system  30  of the present disclosure includes the rotary steering system  40 . The rotary steering system  40  in  FIG. 3  includes one or more steering pads  74  (e.g., one, two, three, four, five, six or more steering pads) that couple to a steering sleeve  76 . The steering sleeve  76  couples to a housing  78  that receives the shaft  60 . In some embodiments, the housing  78  may be referred to as a motor collar. In some embodiments, the drilling motor is configured to generate torque and first rotational speed (revolutions per minute (RPM)) to power the drive shaft  60  that is part of the motor, and the drive shaft  60  causes the drill string  34  to rotate at a second rotational speed or RPM. In some embodiments, there is no drive shaft  60  and the bit  32  is part of or integral to the housing  78 , in which case the torque and RPM are fully provided by the drill string  34 . 
     In operation, the steering sleeve  76  rotates as the drill string  34  rotates. As will be explained in detail below, by coupling and uncoupling the steering sleeve  76  from the housing  78 , the rotary steering system  40  uses the rotation or non-rotation of the housing  78  to control steering of the drill bit  32 . 
     The steering pad(s)  74  may be formed as one piece with the steering sleeve  76 , as shown, or may be formed separately and then coupled to the steering sleeve  76 , for example by bolting, brazing, welding, or fastening (e.g., by threaded fasteners), or the like. In some embodiments, a steering pad  74  may include a body made out of a first material such as carbide (e.g., tungsten or other transition metal carbide). The body may define a curvilinear surface  79  configured to engage the rock face  66  described above. The body may also include a plurality of counterbores  81  in the curvilinear surface  79 . These counterbores  81  enable the steering pad  74  to receive a plurality of inserts  83 . The inserts  83  may include diamond inserts, boron nitride inserts, tungsten carbide inserts, or a combination thereof. The inserts  83  may be conventional polycrystalline diamond cutters (PDC or PCD cutters). These inserts  83  provide abrasion resistance as the steering pad  74  contacts the rock face  66 . 
     As illustrated, the steering pad  74  extends a radial distance  80  beyond the outermost radial surface  82  of the drill bit  32  as defined by the outermost cutter extension, which places the steering pad(s)  74  into contact with the rock face  66  surrounding the bore. In other words, the steering pad  74  is over-gauge, and the radial distance  80  is an over-gauge radial distance. For example, the over-gauge radial distance  80  may be in a range between about 0.1 to 20 mm, 0.1 to 10 mm, and/or 0.1 to 5 mm. In embodiments, the steering sleeve also may include an under-gauge section opposite the over-gauge section, as described in U.S. patent application Ser. No. 15/945,158, incorporated by reference herein in entirety for all purposes. 
     By contacting the rock face  66  the steering pads  74  are able to (passively) force the drill bit  32  in a particular direction (i.e., steer the drill bit  32 ). More specifically, the steering pad  74  forms a steering angle  84  between the drill bit  32  (e.g., outermost surface of a cutter of the drill bit  32 ) and an edge  85  of the steering pad  74 . This steering angle  84  enables the steering pad  74  to change the drilling direction  39  of the drill bit  32 . However, if the steering sleeve  76  rotates with the housing  78 , the influence of the steering pad  74  is negligible or even nonexistent because the effects of the steering pad  74  are felt equally about the circumference of the drill bit  32 . In other words, the effect of the steering pad  74  in a first position is neutralized or canceled when the steering pad  74  is rapidly rotated to a second position that is one hundred and eighty degrees from the first position or continuously rotated at a speed similar to or lower than the drill bit  32 . 
     Accordingly, in order for the steering pad  74  to change the drilling direction of the drill bit  32 , the steering pad  74  is held in place at a particular circumferential position relative to the bore/earth. And in order to block or reduce rotation of the steering pad  74 , the steering sleeve  76  is uncoupled from the housing  78 . 
     The steering sleeve  76  couples and uncouples to the housing  78  with a locking system  86 . In some embodiments, the locking system  86  may include one or more pins  88  (e.g., one, two, three, four, five, six, seven, eight, nine, ten or more pins) that move axially in directions  90  and  92  to couple and uncouple the steering sleeve  76  and housing  78 . More specifically, the pins  88  engage apertures  94  on an end face  96  of the steering sleeve  76  to couple the housing  78  to the steering sleeve  76 . In some embodiments, the pins  88  may radially engage a portion of the steering sleeve  76  overlapped by the housing  78 . In some embodiments, instead of pins  88  the housing  78  and steering sleeve  76  may couple together or engage with gear teeth of dogs, or any other mechanism known in the art to selectively lock and unlock a torsional coupling, including without limitation a sleeve brake system (see, e.g., discussion below with reference to  FIG. 4  (item  142 )) which may be sufficiently powerful to remove the need for pins  88  or the like. In some embodiments, there may be a mechanical friction brake with friction pads similar to a clutch (see, e.g., discussion below with reference to  FIG. 5  (item  160 )). 
     The pins  88  are controlled with actuators  98 . The actuators  98  may be mechanical actuators and/or hydraulic actuators capable of extending the pins  88  in axial direction  92  to engage the steering sleeve  76  and to retract the pins  88  in axial direction  90  to uncouple them from and thereby disengage the steering sleeve  76 . In  FIG. 3 , the actuators  98  are coupled to the housing  78 , but in some embodiments the actuators  98  may be coupled to the steering sleeve  76 . Actuators  98  on the steering sleeve  76  would accordingly extend the pins  88  into and retract them from apertures in an end face  100  of the housing  78 . In some embodiments, there may be a combination of actuators  98  on both the steering sleeve  76  and on the housing  78  that axially move pins  88  to couple and uncouple the steering sleeve  76  and the housing  78 . 
     To control the lock system  86 , the rotary steering system  40  may include a controller  102  a processor  104  and a memory  106 . For example, the processor  104  may be a microprocessor that executes software to control the operation of the actuators  98 . The processor  104  may include multiple microprocessors, one or more “general-purpose” microprocessors, one or more special-purpose microprocessors, and/or one or more application specific integrated circuits (ASICs), or some combination thereof. For example, the processor  104  may include one or more reduced instruction set computer (RISC) processors. 
     The memory  106  may include a volatile memory, such as random access memory (RAM), and/or a nonvolatile memory, such as read-only memory (ROM). The memory  106  may store a variety of information and may be used for various purposes. For example, the memory  106  may store processor executable instructions, such as firmware or software, for the processor  104  to execute. The memory may include ROM, flash memory, a hard drive, or any other suitable optical, magnetic, or solid-state storage medium, or a combination thereof. The memory may store data, instructions, and any other suitable data. The controller  102  may be positioned on the rig  14  and/or may be part of the measurement while drilling system  42  on the drill string  34 , for example. 
     In operation, the controller  102  may receive feedback from one or more sensors  108  (e.g., position sensors) that detect the position of the steering sleeve  76  and by extension the position of the steering pads  74  with respect to the drill bit  32 . Using feedback from the sensors  108 , the controller  102  is able to control the actuators  98  to uncouple the steering sleeve  76  from the housing  78  in order to position the steering pad  74  in a desired position relative to the bore/earth. In the position shown in  FIG. 3 , the steering pad  74  creates a displacement through contact with the rock face  66  that drives the drilling bit  32  toward lateral direction  110 . 
     In order to maintain the steering pad  74  in a desired position relative to the bore/earth, the rotary steering system  40  may include a steering brake system  112 . The steering brake system  112  may include a brake pad  114  that is capable of moving both radially outward and inward to engage and disengage, respectively, the rock face  66 . In operation, the brake pad  114  creates friction with the rock face  66  to maintain the steering pad  74  in a specific position relative to the bore/earth. In other words, the brake pad  114  is configured to prevent slipping/rotation of the steering pad  74  relative to the bore/earth. In some embodiments, the brake pad  114  is axially aligned with or substantially axially aligned with the steering pad  74  with respect to a central longitudinal axis of the steering sleeve  76 . In some embodiments, the brake pad  114  and steering pad  74  may offset from one another about the circumference of the steering sleeve  76 . For example, the brake pad  114  and the steering pad  74  may be offset from each other about the circumference of the steering sleeve  76  in a range between about 1 to 30 degrees, 1 to 90 degrees, 1 to 180 degrees, and/or 1 to 360 degrees. It should be understood that while a single brake pad  114  is illustrated, the steering brake system  112  may include multiple brake pads  114 , for example, two, three, four, five or more brake pads  114 , spaced about the circumference of the steering sleeve  76 . These brake pads  114  may be evenly or unevenly spaced about the circumference of the steering sleeve  76 . In some embodiments, the steering brake pads  114  may be axially as well as radially offset from each other. In some embodiments, the brake pad  114  may be passive (e.g., not actively controlled) and/or in substantially continuous contact with the formation. In embodiments, there may be no brake pad at all. 
     The brake pad  114  may be composed of the same materials as the steering pad  74  (e.g., carbide with polycrystalline diamond inserts). In other embodiments, the material of the brake pad  114  (e.g., steel) may differ from that of the steering pad  74  (e.g., carbide). In  FIG. 3 , the brake pad  114  shown is actuated with a hydraulic piston  116 . In some embodiments, the hydraulic piston  116  may be pressurized and driven using the pressurized drilling mud  68  flowing through the directional drilling system  30 . For example, the steering sleeve  76  and the housing  78  may include respective apertures  118  and  120  that enable pressurized drilling mud  68  to flow from the cavity  121  to the hydraulic piston  116 . The flow of pressurized drilling mud  68  to the hydraulic piston  116  is controlled with a valve  122  that couples to the controller  102 . The valve  122  may be located on the housing  78  to control the flow of drilling mud  68  through the aperture  120 . In another embodiment, the valve  122  may located on the steering sleeve  76  to control the flow of drilling mud  68  through the aperture  118 . In still other embodiments, both the housing  78  and the steering sleeve  76  may include respective valves to control fluid flow through the respective apertures  120  and  118 . When the valve  122  opens, pressurized drilling mud  68  is able to flow through the apertures  120  and  118  to actuate the hydraulic piston  116 . Actuation of the hydraulic piston  116  drives the brake pad  114  radially outward with respect to the steering sleeve  76  and into contact with the rock face  66 . The friction between the brake pad  114  and the rock face  66  reduces or blocks rotation of the steering sleeve  76  and thus maintains the steering pad  74  in a desired position to control the drilling direction  39  of the drill bit  32 . In some embodiments, the rotary steering system  40  may include seals and/or bearings  124  (e.g., circumferential seals) between the housing  78  and the steering sleeve  76  that direct the drilling mud  68  flowing through the aperture  120  to the aperture  118 . In some embodiments, the steering system  40  may not include the valve  122 , enabling the hydraulic piston  116  to be constantly actuated when drilling mud is flowing through the directional drilling system  30 . 
       FIG. 4  is a cross-sectional view of an embodiment of a directional drilling system  30  with a rotary steering system  40  of the present disclosure. As explained above, directional drilling enables the drill bit  32  to repeatedly change orientation between the rig  14  and a reservoir  12 . Accordingly, after drilling with the drill bit  32  in a first direction, it may be desirable to change the drilling direction  39 . In order to change the position of the steering pad  74 , the controller  102  shuts the valve  122 , enabling the hydraulic piston  116  to radially retract and reduce the contact force between the brake pad  114  and the rock face  66 . The controller  102  also signals the actuators  98  to drive the pins  88  into the apertures  94  to couple the housing  78  to the steering sleeve  76 . Once coupled, the torque from the housing  78  is transferred to the steering sleeve  76 , rotating the steering sleeve  76  and the steering pad  74 . As the steering sleeve  76  rotates, the controller  102  receives feedback from the sensor  108 , enabling the controller  102  to determine when the steering pad  74  is in the desired position. Once the steering pad  74  is in the desired position, the controller  102  may control the actuators  98  to retract the pins  88 , enabling the housing  78  to rotate relative to the steering sleeve  76 . The valve  122  may again be opened, enabling pressurized drilling mud  68  to actuate the hydraulic piston  116 . As the hydraulic piston  116  moves radially outward with respect to the steering sleeve  76 , the brake pad  114  again contacts the rock face  66 , reducing and/or blocking rotation of the steering sleeve  76 . As illustrated in  FIG. 4 , the steering sleeve  76  and steering pad  74  have been rotated one hundred and eighty degrees from their position in  FIG. 3 . In this rotated position, the steering pad  74  creates a (passive/reaction) force through contact with the rock face  66  that drives the drilling bit  32  toward lateral direction  140 . 
     In some embodiments, the rotary steering system  40  may include a sleeve brake system  142  that through a slowing force of friction facilitates alignment between the housing  78  and the steering sleeve  76  in order to align the pins  88  (or dogs with teeth, or other mechanism known in the art to selectively lock and unlock a torsional coupling) with the apertures  94 . For example, the sleeve brake system  142  may slow rotation of the housing  78  and/or steering sleeve  76  in order to align the housing  78  with steering sleeve  76  before actuation of the locking system  86 . The sleeve brake system  142  also may provide for adjustable coupling torque to facilitate locating the bit toolface and setting direction. The sleeve brake system  142  may be a mechanical system, an electromechanical system (e.g., magnets), or a hydro-mechanical system (e.g., powered by drilling mud). In order to actuate the sleeve brake system  142 , the controller  102  may control an actuator  144  in response to feedback from the sensor  108  indicating the position of the steering sleeve  76  relative to the housing  78 . In some embodiments, the sleeve brake system  142  may replace or supplement the locking mechanism  86  (e.g., operate as a primary or secondary locking system). For example, the sleeve brake system  142  may generate sufficient force to couple the housing  78  and the steering sleeve  76  together to block and/or reduce relative motion between the two without the locking system  86 . 
     In some embodiments, the rotary steering system  40  may include a bearing system  146  that enables and/or facilitates rotation of the steering sleeve  76  relative to the shaft  60 . The bearing system  146  includes an inner bearing  148  and an outer bearing  150 . The inner bearing  148  couples to and rotates with the shaft  60 , while the outer bearing  150  couples to the steering sleeve  76 . 
       FIG. 5  is a cross-sectional view of an embodiment of a directional drilling system  30  with a rotary steering system  40  of the present disclosure. The rotary steering system  40  is similar to that described above with reference to  FIGS. 3 and 4 . However,  FIG. 5  illustrates that the rotary steering system  40  may place the valve  122  and sensor  108  in different locations. For example, instead of coupling the valve  122  to the housing  78 , the embodiment in  FIG. 5  couples the valve  122  to the steering sleeve  76  to control the fluid flow through the aperture  118 . Similarly, instead of coupling the sensor  108  (e.g., position sensor) to the housing  78 , the sensor  108  may be coupled to the steering sleeve  76 . In some embodiments, the rotary steering system  40  may include a clutch  160  (e.g., annular clutch) that blocks and/or reduces the level of torque transferred from the housing  78  to the pins  88  when coupled to the steering sleeve  76 . In some embodiments, the clutch  160  may be controlled by the controller  102  in response to feedback from sensors (e.g., sensors  108 ) that detect torque and/or rotational speeds of the directional drilling system  30  (e.g., housing  78 , steering sleeve  76 ). 
       FIG. 6  is a cross-sectional view of an embodiment of a directional drilling system  30  with a rotary steering system  40  of the present disclosure. The rotary steering system  40  is similar to that described above with reference to  FIGS. 3-5 . However, in  FIG. 6  the housing  78  and drive shaft  60  may be one piece. In operation, rotation of the drilling string  34  (e.g., by a top drive  38 ) rotates the housing  76  and drive shaft  60 , which in turn rotates the drill bit  32 . The bearing system  146  therefore may be fed with drilling mud  68  through apertures  168  instead of through the cavity  121  described above. 
       FIG. 6  also illustrates that the rotary steering system  40  may include a different actuator for actuating the piston  116 , as well as different placement of the actuator that controls the sleeve brake system  142 . As explained above, the position of the brake pad  114  may be controlled by a hydraulic piston  116  that moves radially with respect to the steering sleeve  76  in response to pressurized drilling fluid. However, in  FIG. 6  the rotary steering system  40  may include a non-hydraulic actuator  170 . For example, the actuator  170  may be a mechanical actuator (e.g., jackscrew) that couples to the steering sleeve  76 . In operation, the mechanical actuator  170  radially extends and retracts the piston  116  with respect to a longitudinal axis of the steering sleeve  76 . Furthermore,  FIG. 6  illustrates that the actuator  144  for the sleeve brake system  142  may be coupled to the steering sleeve  76  instead of the housing  78 . 
       FIG. 7  is a cross-sectional view of an embodiment of a directional drilling system  30  with a rotary steering system  40  of the present disclosure. Similar to the discussion above, the rotary steering system  40  in  FIG. 7  includes a locking system  200  that couples and uncouples the housing  78  to and from the steering sleeve  76 . The locking system  200  may include one or more pins  88  (e.g., one, two, three, four, five, six, seven, eight, nine, ten or more pins) that move axially in directions  90  and  92  to couple and uncouple the steering sleeve  76  to and from the housing  78 . More specifically, the pins  88  engage apertures  94  on the end face  96  of the steering sleeve  76  to couple the housing  78  to the steering sleeve  76 . In some embodiments, the pins  88  may be oriented to move radially in order to couple and uncouple the housing  78  to and from the steering sleeve  76 . For example, the pins  88  may radially engage a portion of the steering sleeve  76  overlapped by the housing  78 . 
     As illustrated, the pins  88  are controlled with springs  202  (e.g., actuators) that respond to the flow of pressurized drilling fluid (e.g., drilling mud) that flows through the directional drilling system  30 . In  FIG. 7 , the pins  88  are in a retracted position due to the pressurized drilling fluid driving pistons  204  in axial direction  90 . As the pistons  204  move in axial direction  90 , the pistons  204  compress the springs  202 , enabling the pins  88  to retract. Retraction of the pins  88  uncouples the steering sleeve  76  from the housing  78 , enabling the steering sleeve  76  and the housing  78  to move independently. That is, the housing  78  is able to rotate while the steering sleeve  76  remains stationary or substantially stationary (e.g., non-rotationary with respect to the borehole/earth). However, when the drilling fluid is depressurized, the springs  202  drive the piston  204  and pins  88  in axial direction  92  coupling the housing  78  to the steering sleeve  76 . The housing  78  may then be rotated along with the steering sleeve  76  from a first position to a second position in order to reposition the steering pad  74 . Once repositioned, the drilling fluid may again be pressurized to uncouple the pins  88  from the steering sleeve  76 . 
     As pressurized drilling fluid drives operation of the locking system  200 , it also actuates a steering brake system  206 . The steering brake system  206  includes one more brake pads  114  that move both radially outward and inward to engage with and disengage from the rock face  66  to maintain the steering pad  74  in a specific position relative to the bore/earth. The brake pads  114  are actuated with a hydraulic piston  116 . When the drilling fluid is pressurized, drilling fluid may flow through the apertures  118  to actuate the hydraulic piston  116 . Actuation of the hydraulic piston  116  drives the brake pads  114  radially outward with respect to the steering sleeve  76  and into contact with the rock face  66 . The friction between a brake pad  114  and the rock face  66  reduces or blocks rotation of the steering sleeve  76  and thus maintains the steering pad  74  in a desired position to control the drilling direction  39  of the drill bit  32 . However, when the drilling fluid is depressurized, friction between the brake pads  114  and the rock face  66  is reduced, enabling the steering sleeve  76  to rotate with the housing  78 . In this way, the steering system  40  uses the pressure of the drilling fluid to both couple and uncouple the steering sleeve  76  to and from the housing  78  while also controlling actuation of the steering brake system  206 . 
       FIG. 8  is a cross-sectional view of an embodiment of a directional drilling system  30  with a rotary steering system  40 . The rotary steering system  40  is similar to that described above. However,  FIG. 8  illustrates a housing  78  with a groove  230  that receives the steering sleeve  76  between opposing first and second shoulders  232  and  234 . Placement of the steering sleeve  76  in this groove  230  enables the shoulders  232  and  234  to reduce axial movement of the steering sleeve  76  with respect to the drill bit  32  (i.e., block contact between the steering sleeve  76  and the drill bit  32 ). To facilitate movement of the steering sleeve  76  relative to the housing  78 , the steering system  40  includes a bearing  236 . In some embodiments, the bearing  236  may be a radial and axial bearing that enables the steering sleeve  76  to rotate relative to the housing  78 . As explained above, the steering sleeve  76  rotates relative to the housing  78  to enable the repositioning of one or more steering pads  74  from a first circumferential position to a second circumferential position relative to the bore/earth to change the drilling direction  39 . 
       FIG. 9  is a cross-sectional view of an embodiment of a directional drilling system  30  with a rotary steering system  40 . The rotary steering system  40  is similar to that described above. However,  FIG. 9  illustrates a unit  61  with a groove  250  that receives the steering sleeve  76  between opposing first and second shoulders  252  and  254 . Placement of the steering sleeve  76  in this groove  250  enables the shoulders  252  and  254  to reduce axial movement of the steering sleeve  76  with respect to the drill bit  32  (i.e., block contact between the steering sleeve  76  and the drill bit  32 ). To facilitate movement of the steering sleeve  76  relative to the unit  61 , the steering system  40  includes a bearing  256 . In some embodiments, the bearing  256  may be a radial and axial bearing that enables the steering sleeve  76  to rotate relative to the unit  61 . As explained above, the steering sleeve  76  rotates to enable the repositioning of one or more steering pads  74  from a first circumferential position to a second circumferential position relative to the bore/earth to change the drilling direction  39 . As illustrated, the unit  61  may couple to a motor  258 . The motor  258  may be a mud motor or an electric motor that provides torque to the unit  61  to rotate the drill bit  32 . In some embodiments, the unit  61  may couple directly to the drill string  34 , enabling the unit  61  to receive torque from a top drive  38 , kelly drive and/or rotary table. 
     The steering assembly of the present disclosure may be part of, or fixedly coupled or adjustably coupled to, a mud motor, a turbine, an electric motor, or any other suitable component along a drill string. The steering assembly of the present disclosure may be manufactured, formed, or assembled separately from, or as an integral part of (in a single piece) with, any one or more of such other drill string component(s). 
     The embodiments discussed above are susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the embodiments are not intended to be limited to the particular forms disclosed.