BR112019026950B1 - ROTARY VALVE, SYSTEM FOR DIRECTING A DRILL DRILL WITH A ROTARY VALVE, AND, METHOD FOR MAINTAINING ENGAGEMENT BETWEEN SURFACES IN A ROTARY VALVE - Google Patents

Abstract

A rotary valve may include a seat and a rotary actuator, each with a surface, the rotary actuator rotatably mounted in a housing. The surfaces may form a seal due to engagement with an engagement force used to maintain engagement. A bypass device can raise the pressure in a volume sealed in the valve to a constant level above an external pressure. The elevated pressure can produce a pressure differential across the rotary actuator, thereby producing at least a portion of the engagement force. Another deflection device may act between a splined hub and a coupled splined shaft, thereby applying at least a portion of the engagement force through the shaft to the rotary actuator. Fluid flowing through a screen can create a pressure drop, causing a pressure differential across the rotary actuator and applying at least a portion of the engagement force to the surfaces.

Description

TECHNICAL FIELD

[001] The present disclosure relates generally to oil field equipment and in particular to downhole tools, drilling systems and related and increasing resistance to degradation of downhole tools due to corrosion, erosion and other forms of degradation such as chemical degradation, dissolution, etc. More particularly, the present disclosure relates to methods and systems for protecting diamond-based material from fracturing due to impacts during installation and operation, wherein the diamond-based material is used to reduce the rate of degradation of the tool. downhole tool components and/or downhole tool components.

FUNDAMENTALS

[002] Drilling wellholes in an underground formation generally requires controlling a trajectory of the drill bit as the wellbore is extended through the formation. Trajectory control can be used to direct the drill bit to drill vertical, inclined, horizontal, and lateral portions of a wellbore. In general, trajectory control can direct the drill bit into and/or through production zones to facilitate the production of formation fluids, direct the drill bit to drill a portion of a wellbore that is parallel to another wellbore for treatment or production assistance, directing the drill bit to intercept an existing wellbore, as well as many other wellbore configurations. A valve can be used to selectively activate actuators, thereby directing the drill bit, but the valve can be highly susceptible to degradation due to the flow of abrasive fluids through the valve, caustic environment, erosive/corrosive agents, and various other modes of degradation. These valves can be manufactured with a material with increased hardness and a lower rate of degradation, but materials of this type, such as diamond-based materials, can be more brittle and damaged by impacts during operation and/or installation.

[003] Therefore, it will be readily understood that improvements in techniques for protecting components against damage due to impacts and other events are continually necessary.

BRIEF DESCRIPTION OF THE DRAWINGS

[004] Various embodiments of the present disclosure will be understood more fully from the detailed description given below and from the attached figures of various embodiments of the disclosure. In the figures, similar reference numbers may indicate identical or functionally similar elements. Embodiments are described in detail below with reference to the accompanying figures, in which: FIG. 1 is a representative partial cross-sectional view of an earth well system including a downhole tool illustrated as part of a tubing string in accordance with an example embodiment of the disclosure; FIG. 2 is a representative partial cross-sectional view of a marine-based well system with one or more downhole tools, in accordance with exemplary embodiment(s) of the disclosure; FIG. 3A-3B are representative cross-sectional views of exemplary embodiments of the downhole tool of FIG. 1 with a turbine-driven motor/generator to control a rotary valve; FIG. 4 is a representative perspective view of the components of the rotary valve of FIG. 3 illustrating an exploded view of an example valve seat and rotary actuator; FIGS. 5A-5D are representative perspective views of the valve seat and rotary actuator of FIG. 4 with the rotary actuator rotated to various positions relative to the valve seat, with the resulting fluid flow through the rotary valve indicated by flow arrows for each rotational position; FIG. 6 is a schematic representation of a hydraulic circuit utilizing the rotary valve of FIG. 4 for selectively actuating a plurality of pistons in a downhole tool. FIG. 7 is a representative perspective view of a splined hub and splined shaft coupled to drive the rotary actuator of the rotary valve; FIG. 8 is a representative cross-sectional view of another exemplary embodiment of the downhole tool of FIGS. 3A-3B with a biasing device used to influence the rotary actuator to engage the valve seat; FIG. 9 is a representative cross-sectional view of another exemplary embodiment of the downhole tool of FIGS. 3A-3B with a pressure differential used to tilt the rotary actuator to engage the valve seat; FIG. 10A is a representative functional diagram of a seal that equalizes pressure across the seal when the seal is at the surface and prevents fluid communication beyond the seal; FIG. 10B is a representative functional diagram of the seal with a bypass device that maintains a constant pressure differential across the seal when the seal is at the surface and prevents fluid communication after sealing; FIG. 11A is a representative functional diagram of a seal that equalizes pressure across the seal when the seal is at the bottom of the well and prevents fluid communication beyond the seal; FIG. 11B is a representative functional diagram of the seal with a bypass device that maintains a constant pressure differential across the seal when the seal is bottomed out and prevents fluid communication beyond the seal.

DETAILED DESCRIPTION OF THE DISCLOSURE

[005] The disclosure may repeat reference numbers and/or letters in the various examples or Figures. This repetition is for simplicity and clarity and does not, in itself, dictate a relationship between the various modalities and/or configurations discussed. In addition, space-related terms such as below, below, bottom, above, top, top of well, bottom of well, upstream, downstream, and the like may be used herein to facilitate description to describe an element or relationship of the resource with other element(s) or resource(s), as illustrated, the ascending direction being that towards the top of the corresponding figure and the descending direction being that towards the bottom of the corresponding figure, the wellhead direction being that towards the surface of the wellbore, bottomhole direction being that towards the toe of the wellbore. Unless otherwise stated, space terms are intended to encompass different orientations of the apparatus or operation in use in addition to the orientation depicted in the figures. For example, if an apparatus in the Figures is turned, elements described as being “below” or “below” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass either an above or below orientation. The device may be oriented differently (rotated 90 degrees or in other orientations) and the space-related descriptors used in this document may be interpreted in the same way.

[006] Furthermore, even though a figure may represent a horizontal wellbore or a vertical wellbore, unless otherwise indicated, it should be understood by those skilled in the art that the apparatus according to the present disclosure is equally suitable for use in well holes having other orientations including vertical well holes, inclined well holes, multilateral well holes or the like. Likewise, unless otherwise indicated, even though a Figure may represent a land operation, it should be understood by those skilled in the art that the method and/or system, in accordance with the present disclosure, is equally well suited for use in land operations and vice versa.

[007] As used herein, the words “comprises”, “has”, “includes” and grammatical variations thereof are each intended to have an open, non-limiting meaning that does not exclude additional elements or steps. When compositions and methods are described in terms of “comprising,” “containing,” or “including” various components or steps, the compositions and methods may also “consist essentially of” or “consist of” the various components and steps. It should also be understood that, as used herein, “first”, “second” and “third”, are assigned arbitrarily and are merely intended to differentiate between two or more objects, etc. , as appropriate, and do not indicate any sequence. Furthermore, it must be understood that the mere use of the word “first” does not require that there be any “second” and the mere use of the word “second” does not require that there be any “first” or “third”, etc.

[008] As used in this document, the term “degradation” and all its grammatical variants (e.g., “degrade”, “degradable”, “degrading”, “dissolve”, dissolve”, “dissolvable”, “erode”, “erode”, “corrosion”, “erosion”, “erosion” and the like) refer to the deterioration of the integrity of an object (or component) made of a solid material, reducing the mass of the solid object by at least one friction sliding between the solid object and other solid objects, an abrasive fluid that flows against parts of the solid object, a hydrolytic degradation, chemical reactions (including electrochemical and galvanic reactions), thermal reactions, or radiation-induced reactions that may degrade the solid object. In some cases, material degradation may be sufficient for the solid object's material mechanical properties to be reduced to a point where the material no longer maintains its integrity and, in essence, causes the solid object to no longer perform its function. its purpose.

[009] The terms in the claims have their simple and common meaning, unless otherwise explicitly and clearly defined by the patent holder. Furthermore, the indefinite articles “a” or “an”, as used in the claims, are defined herein to mean one or more than one of the element they introduce. If there is any conflict in the uses of a word or term in this specification and in one or more patents or other documents that may be incorporated herein by reference, definitions that are consistent with this specification shall be adopted.

[0010] Generally, this disclosure provides a rotary valve that may include a housing and a manifold with multiple flow paths, where the manifold is mounted to the housing. A rotary actuator with a first surface may be rotatably mounted within the housing and a valve seat with a second surface may be fixed or otherwise coupled to the manifold, where the second surface may sealingly engage the first surface to form a fence. It should be understood that the first and second surfaces are defined as the surfaces that engage when the rotary actuator engages the valve seat. The sealing surfaces may be rotatably attached to the respective rotary actuator and valve seat, but need not be fixedly attached to any surface. As used herein, the rotary actuator comprises the first engagement surface, whether a component with the first engagement surface is connected to the rotary actuator or not. The component with the first engaging surface may be rotatably attached to the rotary actuator, but it is not necessary for the component with the first engaging surface to be fixedly attached to the rotary actuator. As used herein, the valve seat comprises the second engagement surface, regardless of whether a component with the second engagement surface is connected to the valve seat or not. The component with the second engagement surface may be rotatably attached to the valve seat, but it is not necessary for the component with the second engagement surface to be fixedly attached to the valve seat. As used herein, the “first and second” engagement surfaces are surfaces that form a seal between the rotary actuator and the valve seat. The rotary actuator may include a clearance that selectively aligns with respective valve seat ports as the rotary actuator rotates relative to the valve seat, selectively pressurizing one or more actuators. A system and method are also provided which may include a rotary valve that selectively causes the pads to extend to a predetermined orientation in the wellbore to direct a drill bit. The azimuthal orientation of a rotary valve actuator can determine which pads are extended and which are retracted as the drill bit rotates. The system and method provide various settings for creating a deflection force to maintain engagement between the rotary actuator and the valve seat.

[0011] FIG. 1 shows a representative partial cross-sectional elevation view of an onshore well system 10 that may include a surface drilling rig 22 (or derrick) 16 used to extend a string of tubing 30 into and through portions of a formation. of underground earth 14. The tubing string 30 may carry a drill bit 102 at its end that can be rotated to drill through the formation 14. A downhole assembly (BHA) 101 interconnected in the tubing string 30 near the drill bit 102 may include components and assemblies (not expressly illustrated in FIG. 1), such as, without limitation, logging-while-drilling (LWD) equipment, measuring-while-drilling (MWD) equipment, a folded sub or housing, a mud motor, a close drill reamer, stabilizers and other downhole instruments. The BHA 101 may also include a downhole tool 100 that may provide direction for the drill bit 102, mud pulse telemetry to support MWD/LWD activities, stabilizer actuation through fluid flow control and/or close drill reamer control through fluid flow control. The direction of the drill bit 102 can be used to facilitate deviations 44, as shown in FIGS. 1 and 2, and/or steering may be used to maintain a section in a wellbore 12 without deviations, as steering control may also be necessary to prevent deviations in the wellbore 12.

[0012] At surface 16, drill bit 22 may be provided to facilitate drilling of wellbore 12. Drill bit 22 may include a turntable 26 that rotates the tubing string 30 and drill bit 102 together around the longitudinal axis X1. The turntable 26 may be selectively driven by a motor 27 and selectively locked to prohibit rotation of the tubing string 30. A lifting device 28 and injector head 34 may be used to manipulate the tubing string 30 into and out of the hole. wellbore 12. To rotate the drill bit 102 with the pipe string 30, the turntable 26 can rotate the pipe string 30 and the mud 36 can be circulated at the bottom of the well by the mud pump 23. The mud 36 can be a calcium chloride brine slurry, for example, which may be pumped through the tubing string 30 and passed through the downhole tool 100. In some embodiments, the downhole tool 100 may be a rotary valve operable to transmit pressure pulses in mud 36, which can be detected on surface 16, as will be understood by those skilled in the art. In other embodiments, the downhole tool 100 may include a rotary valve that selectively applies pressure to various exit flow paths to control various pistons or other hydraulically driven components. Furthermore, mud 36 may be pumped through a mud motor (not expressly illustrated in FIG. 1) in the BHA 101 to rotate the drill bit 102 without having to rotate the tubing string 30 through the turntable 26.

[0013] Mud 36 may be expelled through openings (not shown) in the drill bit 102 to lubricate the drill bit 102 and returned to the surface 16 through an annular space 32 defined between the tubing string 30 and the formation of earth 14. Each of the components (including the downhole tool 100) that is exposed to the mud flow 36 may be susceptible to degradation (e.g., corrosive and abrasive wear). According to embodiments of this disclosure, surfaces that are more prone to degradation due to interaction with the flow of drilling mud 36 (or other potentially abrasive fluids) can be protected by a barrier material that can slow a rate of degradation of the materials. components, thereby prolonging the life of the downhole tool 100. As used herein, “mud 36” or “drilling mud 36” refers to a liquid flowing in the wellbore, whether it flows through a drilling string, treatment string, working string, working string, production string, annulus, etc. Therefore, “36 mud” or “36 drilling mud” may include fluid that flows through a string of tubing during drilling, treating, fracturing, production, or other well system operations. Drilling mud 36 can be used to flow through a drill string, exiting through a drill bit and returning in the annular space. Additionally, drilling mud may indicate fluid flowing from the surface through a string of tubing for treating and/or fracturing operations. Therefore, “36 drilling mud” or “36 mud” is not limited to a fluid used for well drilling.

[0014] FIG. 2 shows a representative partial cross-sectional elevation view of a marine well system 10 that may include a drilling rig 22 (or derrick) mounted on a semisubmersible platform 20 that may float in a body of water above the sea floor ( or surface) 16. Marine well system 10 is shown configured to produce formation fluid. It should be understood that the wellbore system 10 may also be used initially to drill the wellbore 12 as well as perform completion operations such as wellbore 12 treatment operations, fracturing operations, and other production operations. For the production configuration, shown in FIG. 2, a completion assembly 60 may be installed in the wellbore 12. A subsea conduit 18 may extend from a deck 38 of the platform 20 to a subsea wellhead 25, including blowout preventers 24. The platform 20 may have a lifting device 28, a catarina 29 and an injector head 34 for raising and lowering the pipe strings, such as a substantially tubular, axially extending pipe string 30, which may be referred to as a "production column" in this configuration.

[0015] A wellbore 12 may extend through the earth formation 14 and may have a casing string 40 cemented therein. The completion assembly 60 may be positioned in a substantially horizontal portion of the wellbore 12. The completion assembly 60 may include one or more screen assemblies 48 and various other components, such as one or more packers 46, one or more centralizers 50 , etc. Additionally, each screen assembly 48 may include one or more downhole tools 100, which may be flow control devices for managing the flow of fluid into or out of the tubing string 30 through the screen assemblies 48. All of these components may be subject to degradation due to abrasive materials that may be carried by a fluid flowing through the annulus and/or tubing string 30. Downhole tools 100 (such as flow control devices) may be more susceptible to degradation caused by abrasive and/or caustic fluid, as tools 100 may cause fluid flow restrictions and flow redirections. Creating any increased fluid impact on the surfaces of the tool 100 may increase the degradation of the tool 100. The degradation of the tools 100 may be significantly reduced by protecting the surfaces of the tool 100 with a material that has an increased resistance to degradation, such materials to diamond base.

[0016] FIG. 3A shows an example of a downhole tool 100 interconnected in the tubing string 30 that can selectively activate one or more hydraulic actuators. The downhole tool 100 may include a rotary valve 110 with a rotary actuator 120 that is engaged with a valve seat 130. One end 122 of the actuator 120 engages the valve seat 130 while the actuator 120 is rotated relative to the seat. of valve 130 by motor 69. Motor 69 may be any suitable device that can control the rotation of rotary actuator 120, such as a mud motor, electric motor, turbine motor, actuator, etc. FIG. 3A shows a turbine-driven motor/generator 69 with a drive shaft 68 coupled to the actuator 120 through a splined hub 104 which is coupled to a splined shaft 106. The splined shaft 106 may be secured to the support structure 128 on which the end 122 is assembled. Therefore, rotation of the drive shaft 68 can rotate the rotary actuator 120 relative to the valve seat 130.

[0017] The engine 69 may be mounted within a valve housing 64 via brackets 160, with the valve housing 64 mounted within the tool housing 56, as shown. This may couple the engine 69 to the valve seat 130 through the valve housing 64, as a manifold 62 is attached to the valve housing 64 and the tool housing 56. The valve seat 130 may be fixedly attached or coupled to manifold 62, which can permanently align ports in valve seat 130 with flow paths in manifold 62. Therefore, these elements (tool housing 56, valve housing 64, engine chassis 69, valve seat 130, and manifold 62) rotate with the drill bit 102. The motor 69 can rotate the drive shaft 68 relative to the valve housing 64, thereby rotating the rotary actuator 120 relative to the valve seat 130. It should be noted that the actuator rotary 120 and valve seat 130 are held in engagement with each other by an engagement force 97 (FIG. 3B).

[0018] Seals 162, 166 and compensating piston 164 may seal a volume 182 within the valve housing 64 that may contain clean oil 186 to lubricate the moving parts of the rotary valve 110 contained in the volume. Clean oil can be separated from drilling mud 36 by seals 162, 166 and compensating piston 164 to prevent damage to drive components (e.g., motor 69, hub 104, shaft 106) due to degradation of the elements in the drilling mud. drilling (e.g. abrasive particles, corrosive agents, caustic chemicals). Seal 162 may be a stationary seal that seals between the motor housing 69 and the valve housing 64. The compensating piston 164 may seal between the housing 64 and the splined hub 104 that rotates relative to the housing 64. However, The compensating piston 164 may also rotate with the splined hub 104 while maintaining a seal with the valve housing 64 that does not rotate with the hub 104. The compensating piston 164 may also provide pressure equalization between the volume 182 and the sludge. perforation 36, providing pressure communication between volume 182 and mud 36. Compensation piston 164 may also refer to a compensation piston 170 in FIG. 3B. Seal 166 can rotate with hub 104 and shaft 106 when drive shaft 68 rotates and can seal between splined hub 104 and splined shaft 106. Seals 162, 166 and compensating piston 164 create the isolated volume of fluid 182 which may contain the clean oil 186.

[0019] Fluid flow 70 from mud 36 may flow through a turbine 67, causing the turbine 67 to rotate. Rotation of the turbine 67 may generate electricity to power an electrical drive to rotate the drive shaft 68. The turbine may also provide rotation of the drive shaft 68 directly and/or through various other configurations of the motor 69 to control the rotary valve 110 As the drive shaft 68 rotates, the splined hub 104 coupled to the splined shaft 106 transfers the rotational motion of the drive shaft 68 to the rotational motion of the rotary actuator 120. As the rotary actuator 120 rotates in In relation to the valve seat 130, a clearance 116 and a recess 118 selectively align with flow paths 86A, 86B (and 86C or more, if applicable). FIG. 3A shows clearance 116 aligned with flow path 86A, which allows pressurized drilling mud 36 to enter flow path 86A through a port in valve seat 130, thereby pressurizing actuator #1 (shown as piston 52A ) to extend a 152A extendable pad. A second flow path 86B may be aligned with the recess 118 which may direct fluid flow 76B from the flow path 86B to be released into the annular space 32 (or other low pressure volume) through the flow path 84 as flow. of fluid 74, thereby disabling actuator #2 (shown as piston 52B) and retracting pad 152B. As the rotary actuator 120 rotates, the gap 116 may misalign from the flow path 86A and align with the flow path 86B, thereby pressurizing the piston 52B to extend the pad 152B and allowing actuator #1 (or piston 52A) depressurize through recess 118 and flow path 84 into annular space 32, thereby retracting pad 152A. Selective activation of pistons 52A, 52B (and 52C or more, if applicable) selectively extends and retracts pads 152A, 152B (and 152C or more, if applicable). The operation of the rotary valve is discussed in more detail with reference to FIGS. 4 and 5A-5D.

[0020] FIG. 3B shows another example embodiment of a downhole tool 100 interconnected in the tubing string 30 that can selectively activate one or more hydraulic actuators. It should be clear that the rotary valve 110 shown can also be used to create pressure pulses in the drilling mud 36 for communication with the surface, as well as other flow control functions. However, this example is aimed at selective activation of hydraulic actuators, even though pressure pulses can also be created as the rotary valve selects and deselects multiple hydraulic actuators.

[0021] The downhole tool 100 may include a rotary valve 110 with a rotary actuator 120 that is engaged with a valve seat 130 (similar to that of FIG. 3A). An end 122 of the actuator 120 engages the valve seat 130 as the actuator 120 is rotated relative to the valve seat 130 by the motor 69. The end 122 and/or the valve seat 130 may be manufactured from a material ( such as ScD silicon carbide diamond) which provides better resistance to degradation than if the components were made from materials such as tungsten carbide, steel, metal alloys, etc. By increasing the service life of the rotary actuator 120 and valve seat 130, the service life of the downhole tool 100 can also be extended.

[0022] The valve seat 130 may be fixedly attached or otherwise coupled to a flow manifold 62, which may have multiple flow paths to direct the flow of fluid received from the valve seat 130. The flow paths can direct fluid flow to various tool actuators, to the drill bit, to the annulus, to other chambers, and/or other locations on the downhole tool 100 or BHA 101. The manifold 62 may be attached in a manner fixed to the piping string 30 through housing 56, such as welding, brazing, threaded connections, etc. , so that the manifold 62 rotates with the tubing string 30 when the drill bit 102 rotates. This allows ports that may be formed in the tubing string 30 (or housing 56) to remain aligned with one or more of the flow paths from the collector 62, such as a flow path through the collector 62 to the annular space 32 through a wall of the pipe string 30.

[0023] The cylindrical housing 64 can support the components of the rotary valve 110. The ports 87 allow the flow of fluid 77 through the housing 64 from an internal flow passage 80 of the tubing string 30 to the rotary actuator 120 and the valve seat 130. The housing may be fixedly attached to the manifold 62 so that it rotates with the piping string 30 and the valve seat 130. A motor 69 may be mounted within the housing 64 to rotate (direction 90 indicated by the arrows) a drive shaft 68 about a central axis 88 relative to the housing 64. Rotation of the drive shaft will rotate the rotary actuator 120 relative to the valve seat 130, thereby selectively activating and deactivating fluid flow through ports 140A-C in the valve seat 130. An orientation seat 66 can be used to mount a rotary orientation 58 that rotationally mounts the drive shaft 68 in the housing 64 and helps keep the rotary actuator 120 centered within the housing. A screen 112 may be positioned around an outer surface of the housing 64 to filter drilling mud 36 passing through the screen 112 to the rotary valve 110. This screen 112 may prevent objects carried by the mud 36 from damaging the rotary valve 110 , flow paths and/or actuators controlled by the rotary valve.

[0024] A portion 77 of the fluid flow 70 from the drilling mud 36 may enter the rotary valve 110 through the screen 112 and through the ports 87. The remaining portion of the fluid flow 70 may travel through the bypass flow path 82 as fluid flow 72 to continue into the drill bit 102. As seen in FIG. 3, the rotary actuator 120 is in a rotated position that allows fluid flow 77 to enter flow path 86A in manifold 62 as fluid flow 76A. Fluid flow 76a may then be directed through flow path 86A to an actuator #1, such as a downhole tool component actuator 100 and/or an actuator of another downhole tool. Pressure developed in actuator #1 due to fluid and pressure communication through the rotary valve 110 may be released when the rotary valve 110 rotates to a different position that prevents fluid and pressure communication through the rotary valve 110 into the flow path 86A. The developed pressure can be vented through the rotary valve 110 through the flow path 84 as fluid flow 74, which can be directed to a low pressure volume such as the annular space 32. This allows actuator #1 to be deactivated. .

[0025] The drive shaft 68 may be positioned concentrically within an extended motor housing 65 and configured to rotate within the motor housing 65. An annular space 184 may be formed between the drive shaft 68 and the motor housing 65 The drive shaft 68 may also include a central flow passage 188 that may communicate the pressure in the oil 186 to the rotary actuator 120. If the pressure in the oil 186 is greater than the pressure of the mud 36 in a chamber 177 (through the which fluid flow 77 travels), a pressure differential across the rotary actuator 120 can create an engagement force 97 that impels engagement of the rotary actuator 120 with the valve seat 130. The pressure equalization ports 190 and 192 maintain equal pressure within the sealed volume 182, allowing pressure communication between an annular space 185, an annular space 184 and the central flow passage 188. Therefore, the oil pressure 186 in the sealed volume 182 remains equalized and the pressure exerted on the side left (in relation to FIG. 3B) of rotary actuator 120 (and rotary bearing 58) is equal to the pressure in annular space 185.

[0026] The downhole tool 100 of FIG. 3B is similar to downhole tool 100 of FIG. 3A, which also includes a motor 69 with brackets 160, a valve housing 64, a screen 112, a manifold 62, a rotary actuator 120, and valve seat 130, as well as the flow paths and actuators described with reference to FIG. . 3A. However, tool 100 of FIG. 3B differs from FIG. 3A at least including a deflection device 172 that provides a compensating force to the oil 186 in the isolated volume 182. The deflection device 172 is shown as a coil spring, but other deflection devices may be used, such as compression rings. and any other suitable bypass device that can produce a constant compensation pressure in the oil 186, where the compensation pressure is added to the pressure external to the isolated volume 182. It should be clear that a bypass device 172 may also be used in the tool 100 of FIG. 3A, in accordance with the principles of this disclosure.

[0027] A compensating piston 170 can communicate pressure between a chamber 178 and annular space 185, while preventing fluid communication between them. As the pressure changes in the annular space 185 or chamber 178, the compensating piston 170 may move along the motor housing 65 to compensate for any pressure changes, thereby equalizing the pressure in the space 185 with the pressure in the chamber 178 , assuming that the bypass device 172 was not present. At least two options are given in FIG. 3B to establish pressure in chamber 178. Equalizing ports 96 may be positioned at various locations in valve housing 64 to establish pressure in chamber 178. An annular space 176 is shown as an annular space between screen 112 and the housing. of valve 64. The ports 96 shown as solid lines can provide pressure equalization between the annular space 176 and the chamber 178. The pressure in the annular space 176 is equal to the pressure in the chamber 177 due to the ports 87 in the valve housing 64. Therefore , with this positioning of the ports 96, the pressure in the chamber 178 can be equalized with the pressure in the annular space 176 and the chamber 177. Alternatively, one or more ports 96 can be positioned in the valve housing 64 so as to provide communication of pressure between the flow passage 80 and the chamber 178. In this configuration, the ports 96 with the solid lines are removed and the port 96 illustrated with dashed lines can be formed in the valve housing outside the screen 112. Therefore, the pressure in the chamber 178 178 is equalized with the pressure in the flow passage 80 of the tubing string 30.

[0028] Therefore, without the bypass device 172, the oil pressure 186 would be maintained at the pressure of the drilling mud 36 in the flow passage 80 (using port 96 with dashed lines) or equal to the pressure in the annular space 176 (using 96 ports with solid lines). It should also be understood that the pressure in the chamber 178 is equal to the pressure in the flow passage 80, regardless of the position of the ports 96 when the rotary valve 110 is at the surface or when fluid is not flowing through the rotary valve 110, since the pressure may equalize between the chamber 178, the flow passage 80, the annular space 176 and the chamber 177, i.e. if the bypass device 172 is not provided.

[0029] However, if the bypass device 172 is provided, then the oil pressure 186 can be maintained at a pressure that is the pressure in the chamber 178 plus a compensation pressure K (see FIGS. 10 and 11). This compensation pressure K can provide a positive engagement force 97 to maintain engagement of the rotary actuator 120 and the valve seat 130 during surface mounting of the valve 110 and drill string 30, installation in the wellbore 12, and operation of downhole of the rotary valve 110. The bypass device 172 may be configured to provide a desired compensation pressure K in the oil 186, thereby providing a desired engagement force 97 to protect the actuator 120 and the valve seat 130 from damage due to to impacts that may be caused when the actuator 120 is moved away from the valve seat 130 and then engages the valve seat 130 again with an impact on the engagement surfaces 138, 132 of the actuator 120 and the valve seat 130, respectively. However, the deflection device 172 is not necessary to produce the desired engagement force 97.

[0030] FIG. 4 shows a perspective view of the rotary actuator 120 and valve seat 130 of the rotary valve 110 without the other components of the rotary valve 110 for clarity. Furthermore, the actuator 120 and the valve seat 130 are shown separated by a space between the surfaces 138 and 132. However, in operation, the surfaces 138 and 132 closely fit together to form a seal. The rotary actuator 120 may rotate in any direction 90 about the central axis 88. The splines 78 may be coupled to the drive shaft 68 (e.g., through the splined hub 104 and the splined shaft 106, where the splined shaft may include the splines 78) and used to rotate the rotary actuator 120. The end 122 of the actuator 120 may be formed as a cylinder with a gap 116 formed in the circumference of the cylinder and a recess 118 formed in the surface 138 of the end 122. The recess 118 may be extend through the end 122 and further into the main body of the actuator 120, if desired. A structure 128 of the main body of the actuator 120 may be used to support the end 122, which may be composed of layers 124, 126. The layer 124 may be made of a degradation-resistant material (or materials) to reduce the rate of degradation. of the rotary actuator 120. Degradation in the actuator 120, and in particular up to the end 122, may be caused by the fluid flowing through the rotary valve 110, as well as by the engagement forces experienced by the surface 138 of the actuator 120 and the surface 132 of the valve seat 130. It should be understood that end 122 may be made of a single layer of a degradation-resistant material without having two individual layers 124, 126. Both layers may be necessary when a layer 126 (or substrate) is used to support a layer of degradation-resistant material 124, such as polycrystalline diamond PCD. Single layer configuration can be used when ScD Silicon Carbide Diamond is used as degradation resistant material.

[0031] The valve seat 130 of this rotary valve 110 may be composed of layers 134, 136. The layer 134 may be made of a degradation-resistant material (or materials) to reduce the rate of degradation of the valve seat 130. Likewise, degradation in the valve seat 130 may be caused by fluid flowing through the rotary valve 110, as well as the engagement forces experienced by the surfaces 138 and 132. It should be understood that the valve seat 130 may be made of a single layer of a degradation-resistant material (e.g., ScD) without two individual layers 134, 136. Both layers may be necessary when a layer 136 (or substrate) is used to support a layer of degradation-resistant material 134, such as PCD polycrystalline diamond. Valve seat 130 may include ports 140A-C and 142 for controlling fluid flow with each of these ports associated with one or more flow paths in manifold 62.

[0032] The operation of valve 110 shown in FIG. 4 is illustrated by FIGS. 5A-5D. These figures show the various rotational positions of the rotary actuator 120 relative to the valve seat 130. The following discussion at least describes how this embodiment of the rotary valve 110 operates to selectively provide and receive fluid flow through ports 140A-C and 142 of valve seat 130. Ports 140A-C may be associated with actuators #1, #2, and #3, respectively, through flow paths in manifold 62 (not shown in FIGS 5A-5D).

[0033] FIG. 5A shows the rotary actuator 120 rotated so that the space 116 is aligned with the port 140A and at least a portion of the recess 118 is aligned with the ports 140B, 140C and port 142. The port 142 remains aligned with a portion of the recess 118 which is centered on the central axis 88. The fluid flow 77 that has passed through the screen 112 and the ports 87 can pass through the port 140A as flow 76A and be directed by the manifold 62 to an actuator #1. The flow 76A can pressurize the actuator #1 and thus activate actuator #1. However, fluid flow 77 is prevented from flowing through ports 140B, 140C since rotary actuator 120 is blocking these fluid flow ports 77.

[0034] Through previous revolutions of the rotary actuator 120, actuators #2 and #3 could have been pressurized through ports 140B and 140C, respectively, through fluid flow 76B and 76C, respectively. Therefore, with ports 140B and 140C at least partially aligned with recess 118, pressure in actuators #2 and #3 can be released by fluid flows 76B and 76C, as indicated by arrows showing fluid flows 76B, 76C. flowing back through ports 140B, 140C into recess 118. These fluid flows 76B, 76C can be diverted through recess 118 (shown as U-shaped arrows 75) to port 142 as fluid flow 74 and directed through manifold 62 to annular space 32 (or any other low-pressure volume), thereby releasing pressure on actuators #2, #3. In this way, port 142 may also be referred to as a drain port 142. However, if there were no pressure in actuators 2 and 3, fluid flow 76B, 76C would be minimal, if at all.

[0035] FIG. 5B shows actuator 120 rotated further in direction 90 so that port 140B is no longer aligned with recess 118. However, port 140C remains aligned with recess 118, allowing pressure equalization of actuator #3 with the low pressure volume (e.g., annular space 32) by fluid flow 76C through port 140C, into recess 118 which redirects fluid flow 76C (indicated by U-shaped arrow 75) into the drain port 142 as fluid flow 74, which may be directed into annular space 32 by manifold 62. Ports 140A, 140B are at least partially aligned with gap 116, allowing fluid flow 77 to enter both ports, pressurizing and activating actuators #1 and #2.

[0036] FIG. 5C shows actuator 120 rotated further in direction 90 so that ports 140A, 140C are at least partially aligned with recess 118, allowing pressure in actuators #1 and #3 to be released by fluid flows 76A, 76C through ports 140A, 140C, respectively, into recess 118 which redirects fluid flows 76A, 76C (indicated by U-shaped arrows 75) to port 142 as fluid flow 74, which is directed to annular space 32 by manifold 62. Port 140B is fully aligned with gap 116, allowing fluid flow 77 to enter the port, thereby continuing to pressurize actuator #2.

[0037] FIG. 5D shows actuator 120 rotated further in direction 90 so that port 140A is aligned with recess 118, allowing pressure in actuator #1 to be further released by fluid flow 76A through port 140A into recess 118 that redirects fluid flow 76A (indicated by U-shaped arrow 75) into drain port 142 as fluid flow 74, which is directed to annular space 32 by manifold 62. Ports 140B, 140C may be at least partially aligned with gap 116, allowing fluid flow 77 to enter both ports, thereby pressurizing actuators #2, #3. As rotary actuator 120 continues to rotate, these settings (as well as other intermediate settings) of rotary valve 110 may be repeated until the actuator 120 is no longer rotated.

[0038] FIG. 6 shows a schematic diagram of an example rotary valve 110 (which may include similar components as shown in FIG. 4), being used to selectively activate and deactivate actuators #1, #2, #3 which are shown as pistons 52A -C, respectively. However, other rotary valves 110 may be substituted for the rotary valve 110 and more or fewer pistons may be supported by this configuration shown in FIG. 6. The rotary valve 110 may be used to synchronize the pad extensions of a downhole tool 100 with the rotation of the drill bit 102 and to facilitate steering of the drill bit 102 through selective pad extensions.

[0039] Drilling mud 36 can be pumped from surface 16 as fluid flow 70 through tubing string 30 through internal flow passage 80. This mud 36 can be referred to as a “high” pressure side of the system. Part of the mud fluid flow 70 may be diverted as flow 77 to supply fluid and pressure to the rotary valve 110, with the remainder (and majority) of the mud 36 flowing to the drill bit 102 as fluid flow 72 under "high " pressure. The diverted flow 77 may pass through a screen 112 to filter any debris or other objects from the fluid before entering the rotary valve 110.

[0040] As the mud 36 flows through the drill bit 102 and into the annular space 32, the mud 36 may experience a pressure drop across the drill bit 102. Therefore, the annular space 32 can be referred to as a “low” pressure side of the system. The rotary valve 110 can be connected between the “high” pressure side and the “low” pressure side, as shown in FIG. 6. Fluid flow 77 may enter the rotary valve 110 from the high pressure side through ports 87 (not shown) and space 116 to selectively pressurize actuators #1, #2, #3 and then exit the valve rotary 110 to the “low” pressure side via port 142 which is in fluid communication with the annular space 32 (a low pressure volume) via flow path 84. These pistons 52A-C can be connected to ports 140A- C through flow paths 86A-C, respectively. As the rotary actuator 120 is rotated, pistons 52A-C are selectively activated and deactivated.

[0041] When gap 116 is aligned with port 140A, then pressure can be applied to flow path 86A and thereby activate piston 52A. When the gap 116 is aligned with the port 140B, then pressure can be applied to the flow path 86B and thereby activate the piston 52B, with the pressure in the piston 56A being released through the drain port 142 into the flow path. 84 as fluid flow 74, which may be dumped into the annular space 32 (or other low pressure volume), where it may join the mud flow 71 flowing back to the surface 16. When the space 116 is aligned with the port 140C, then pressure can be applied to flow path 86C and thereby activate piston 52C, with the pressure on pistons 56A, 56B being released through drain port 142 to flow path 84 as fluid flow 74 , which can be dumped into the annular space 32, where it can join the mud stream 71 flowing back to the surface 16. This sequence can continue as long as the rotary actuator 120 continues to rotate relative to the valve seat 130. How can this be seen in FIG. 6, gap 116 is shown as being aligned with port 140B, which allows pressure to be applied to piston 52B through flow path 86B. The piston 52B is shown extended in the piston chamber 52B with the piston 52B extending the pad 152B radially to contact an interior surface (or wall) of the wellbore 12.

[0042] In one example, the rotary valve 110 can be used to direct the drill bit 102 as the drill bit rotates to extend the wellbore 12. Pistons 52A-C can be used to extend and retract the drill pads. orientation 152A-C, respectively, which may be circumferentially spaced on an exterior of the piping string 30 (or housing 56). As these orientation pads 152A-C are selectively extended in contact with the wellbore 12, the tubing string 30 can be pushed away from the wellbore wall contacted by an extended pad and pushed toward an opposite wall of the wellbore. well hole. If the selected guidance pads 152A-C are periodically extended, then the drill bit 102 can be guided in an azimuthal direction away from the longitudinal axis X1 to change the trajectory of the drill bit 102 through the earth formation 14 as it wellbore 12 is extended. To periodically extend the orienting pads 152A-C in a desired azimuth orientation relative to the wellbore 12, the orienting pad extensions can be synchronized with the rotation of the tubing string 30 using the rotary valve 110 to control the extensions and retractions of the 152A-C extendable guidance pads.

[0043] With the housing 56 rotating at a given RPM, then the motor 69 can be controlled to rotate the drive shaft 68 (and therefore the rotary actuator 120) at the given RPM, but in an opposite direction. Therefore, the rotary actuator 120 can be viewed as “geostationary” compared to the earth formation 14 and the wellbore 12. As the drill bit 102 rotates, the rotary actuator 120 can rotate relative to the valve seat. 130 (which rotates with drill bit 102 and housing 56). Once the actuator 120 is set to a desired azimuthal orientation relative to the wellbore 12 by the motor 69, then the motor 69 can maintain that orientation relative to the wellbore 12 when the drill bit 102 rotates, rotating the actuator. 120 in the opposite direction at the same speed as the drill bit 102. As the valve seat 130 rotates with the drill bit 102, it will present ports 140A-C in sequence to the clearance 116 of the rotary actuator 120, thereby pressurizing the associated piston 52A-C when individual ports 140A-C are aligned with clearance 116

[0044] As each individual port 140A-C moves out of alignment with the gap 116, it aligns with a recess 118 in the rotary actuator 120 that provides fluid communication between the port aligned with the recess 118 and the drain port 142, thereby freeing the pressure on the respective piston 52A-C through the flow path 84 to the annular space 32. With the “geostationary” actuator 120, it can be seen that each extended block due to the alignment of the space 116 with the individual ports 140A-C, will be extended in a desired azimuthal orientation, which is determined by the azimuthal orientation of the actuator 120 relative to the wellbore 12, where the desired azimuthal orientation of the actuator 120 may be different from the desired azimuthal orientation for extending the individual pads 152A-C. In this way, periodic pad extensions in the same desired azimuthal orientation can continue to direct the drill bit 102 in a desired azimuthal orientation (which may also be different from the other azimuthal orientations) away from the central longitudinal axis X1 of the wellbore 12 .

[0045] Referring again to FIG. 4, at least one of the generally flat, disc-shaped first and second mating surfaces 138, 132 may be constructed of an ScD material to inhibit or resist degradation of the rotary valve 110 in operation. As illustrated, the rotary actuator 120 may be constructed with a wear surface 138 of an ScD composite forming the end 122 (where the end 122 may be one layer of “T2” thickness rather than two layers 124, 126 as described previously) and is attached to a support structure 128. The support structure 128 may be constructed of a material, e.g., WC and/or cemented carbide that is different from the ScD composite end 122. In some embodiments, the composite end of ScD 122 can be connected to the support structure 128 by brazing techniques at brazing temperatures between 650 and 925 °C. Using furnace brazing methods and active brazing alloys, it is possible to obtain shear forces of 250 to 350MPa. The ScD 122 composite end is thermally stable, at least in part because the ScD 122 composite end does not contain the interstitial cobalt (Co) catalyst present in sintered PCD. Thus, thermal degradation due to expansion and thermal graphitization of Co does not occur with brazing even at temperatures exceeding 700 degrees Celsius and the rotary actuator 120 can remain structurally stable without cracking. In some embodiments, the rotary actuator 120 may be constructed from a monolithic piece or bonded pieces of ScD composite material.

[0046] Rotation of the rotary actuator 120 relative to the valve seat 130 may cause frictional contact between the engaging surfaces 138, 132. Since the coefficient of friction of the ScD component may be relatively low, the rotational movement between engagement surfaces 138, 132 can be achieved with relatively low energy expenditure and relatively low abrasive wear.

[0047] The valve seat 130 can be manufactured from a monolithic piece or from linked pieces of ScD composite material. The monolithic part or parts attached may be polished to form ports 140A-C and drain port 142. Therefore, engagement surface 132 and ports 140A-C, 142 expose fluid flow through valve seat 130 to surfaces made of ScD and can provide significant resistance to degradation of the valve seat 130. The valve seat 130 may also be welded using standard brazing alloys at standard brazing temperatures (e.g., temperatures greater than 650 degrees) to provide a upper connection between valve seat 130 and manifold 62.

[0048] FIG. 7 shows the splined hub 104 engaged and coupled to the splined shaft 106. The splined hub 104 transmits the rotational movement of the transmission shaft 68 to the splined shaft 106 due to the engagement of the splined hub 104 with the splined shaft 106. The engagement of the splines makes whereby the hub 104 and the shaft 106 rotate together as a unit, allowing lateral (i.e., longitudinal) movement of the shaft 106 relative to the hub 104. Therefore, the splined shaft 106 can move longitudinally (i.e., the Z axis ) relative to the splined hub 104. The splined interface allows sufficient freedom of longitudinal movement for the rotary actuator 120 (frame 128 of actuator 120 shown) to self-adjust to the relative movement of the valve seat 130.

[0049] FIG. 8 is a simplified partial cross-sectional view of a rotary valve 110 similar to the valve 110 shown in FIG. 3A. However, FIG. 8 has a bypass device 174. It is to be understood that this bypass device 174 may also be used in the rotary valves shown in FIGS. 3A and 3B, as well as other embodiments of the rotary valve 110. The bypass device 174 may be positioned between an end 200 of the splined shaft 106 and an inner shoulder 202 of the splined hub 104. The bypass device 174 may apply a force 98 to the splined shaft 106 which can transmit the force 98 to the rotary actuator 120, thereby applying the force 98 to the rotary actuator 120 to urge the surface 138 to engage with the surface 132 on the valve seat 130. This engagement force 98 can also maintain an engagement of surface 138 with surface 132 during assembly of valve 110 and/or drill string 30 on surface 16, installation of valve 110 in wellbore 12, and downhole operation of valve 110. The deflection device 172 is shown as a coil spring, but other deflection devices such as compression rings, expandable foam, and any other suitable deflection device that can produce the force 98 against the splined shaft 106 and the surface may also be used. coupling force 138. It should be understood that force 98 in FIG. 8 may also include the force 97 produced by the diverter device 172 when the drive shaft 68 has the central flow passage 188 (see FIG. 3B) through which fluid pressure in the sealed volume 182 may be applied to the shaft 106. The sealed volume 182 may contain the clean oil 186.

[0050] FIG. 9 illustrates yet another way of applying an engagement force (shown here as engagement force 99) to the rotary actuator 120 to maintain engagement between the rotary actuator 120 and the valve seat 130 when pressurized fluid is flowing through the rotary valve 110. With flow passage 80 in pressure communication with sealed volume 182, pressure P2 in the sealed volume will be equal to pressure P1 in flow passage 80, through compensating piston 170 and port 96 (i.e., port dashed line 96 in FIG. 3B). Therefore, the pressure P1 is equal to P2, with P2 being applied to the left side (relative to the figure) of the splined shaft 106. A portion of the drilling mud 36 enters the rotary valve 110 through the screen 112 as fluid flow 77. The screen 112 (or filter) can create a pressure drop in the drilling mud across the filter, resulting in a pressure P3 in the chamber 177 that is less than the pressure P1 in the flow passage 80. This pressure P3 can be applied to the side right (in relation to the figure) of the splined shaft 106 of the chamber 177, thus creating a pressure differential across the splined shaft 106, since P3 is smaller than P2. As an example, if P1 is 1,000 psi, P2 would be 1,000 psi due to pressure equalization between flow passage 80 and sealed volume 182. If the pressure drop across screen 112 were 50 psi, pressure P3 in chamber 177 it would be 950 psi. The pressure differential across spline shaft 106 would also be 50 psi, since P2 - P3 is 50 psi in this example. The pressure values presented here are merely stated to help illustrate the operation of producing force 99 due to a pressure differential across the splined shaft 106.

[0051] As can be seen, there are at least three different ways of applying an engagement force to maintain engagement of the rotary actuator 120 with the valve seat 130. One way produces the engagement force 97, due to the production of pressure. compensation K in sealed volume 182 via bypass device 172 as described with reference to FIG. 3B. Another way produces the engagement force 98 due to the deflection device 174 applying a deflection force to the splined shaft 106 as described with reference to FIG. 8. The third way produces the engagement force 99, due to a pressure differential between the sealed volume 182 and the chamber 177. Two or more of these engagement forces may be combined as needed to apply a desired engagement force to the rotary actuator 120.

[0052] For example, the offset device 172 may be employed without the additional offset device 174. During mounting the drill string 30 to the surface and installing the drill string in the wellbore 12, the force 97 may maintain a engagement of the rotary actuator 120 with the valve seat 130. After drilling begins and the mud 36 is pumped through the drill string 30, then additional engagement force 98 (due to the pressure differential across the splined shaft 106) may be combined with the force 97 to maintain engagement of the rotary actuator 120 with the valve seat 130. Additionally, the deflection device 174 may also be used, which may produce the engagement force 99 by applying an engagement force to the rotary actuator 120 that combines forces 97, 98 and 99. Additionally, if no bypass device 172, 174 is used, then the pressure differential across the splined shaft may provide the engagement force 99 when the rotary valve 110 has pressurized the fluid flowing through it. However, with this configuration, fluid flow through valve 110 is necessary to produce the pressure differential across rotary actuator 120.

[0053] FIGS. 10A and 10B show a simplified functional diagram to illustrate how the bypass device 172 can be used to produce the compensation pressure K on the surface 16. The compensation piston 170 can slide in the valve housing 64 to adjust the pressure changes in the sealed volume 182 (containing clean oil 186) or in chamber 178 (which may contain ambient air 180 at surface 16). Compensation piston 170 provides pressure communication between volume 182 and chamber 178, but does not provide fluid communication between them. If the rotary valve 110 is at the surface (e.g., during drillstring assembly), then the chamber 178 can be filled with air 180 at atmospheric pressure. Therefore, pressure P1 in chamber 178 may be atmospheric pressure at surface 16, and since compensation piston 170 provides pressure communication, pressure P2 in sealed volume 182 is equal to P1, both being equal to atmospheric pressure. In FIG. 10B, the bypass device 172 has been added to the side of the chamber 178 of the compensation piston 170, between the compensation piston 170 and a shoulder of the valve housing 64. The bypass device 172 can provide a compensation pressure K. Therefore, the pressure P2 in the sealed volume 182 may be the compensation pressure K combined with the pressure P1. This compensation pressure K may be applied to the rotary actuator 120 to maintain engagement with the valve seat 130.

[0054] FIGS. 11A and 11B show a simplified functional diagram to illustrate how the bypass device 172 can be used to produce compensation pressure K at the bottom of the well. The compensation piston 170 which can slide in the valve housing 64 to adjust pressure changes in the sealed volume 182 or chamber 178. Again, the compensation piston 170 provides pressure communication between the volume 182 and the chamber 178, but not provides fluid communication between them. If the rotary valve 110 is downhole (e.g., during drilling operations), the chamber 178 may be filled with pressurized drilling mud 36 at pressure P1, causing the pressure P2 in the sealed volume 182 to be equal to P1 . In FIG. 11B, bypass device 172 has been added to the chamber 178 side of compensation piston 170, as in FIG. 10B. The bypass device 172 can provide the compensation pressure K to the sealed volume 182. Therefore, the pressure P2 in the sealed volume 182 can be the compensation pressure K combined with the pressure P1. This compensation pressure K can be applied to the rotary actuator 120 to maintain engagement with the valve seat 130 at the bottom of the well.

[0055] Thus, a rotary valve 110 is provided which may include a valve housing 64, a manifold 62 mounted on the valve housing 64, a rotary actuator 120 rotatably mounted within the valve housing 64 with the rotary actuator 120 having a first engaging surface 138, a valve seat coupled to the manifold and the valve seat having a second engaging surface 132 that sealably engages the first engaging surface 138 and forms a seal between the first and second engaging surface 138, 132. An engagement force 97, 98, 99 may be applied to the rotary actuator 120 to maintain engagement between the first and second engagement surfaces 138, 132.

[0056] For any of the previous embodiments, the valve 110 may include any of the following elements, individually or in combination with each other:

[0057] Manifold 62 may include multiple flow paths 86A-C, valve seat 130 may include ports 140A-C that are in fluid communication with respective flow paths 86A-C in manifold 62, and rotary actuator 120 may include a gap 116 that selectively aligns with the respective valve seat ports 140A-C when the rotary actuator 120 rotates relative to the valve seat 130. An engagement force 97, 98, 99 may be created by at least one of a first bypass device 172, a second bypass device 174, and a pressure differential across the rotary actuator 120. At least a portion of the engagement force 97, 98, 99 may be created by the first bypass device 172 acting on a piston compensation 164, 170.

[0058] Valve 110 may include a sealed volume 182 within the valve housing 64, where the compensating piston 164, 170 may provide pressure communication between the sealed volume 182 and a first flow passage 80, 176 external to the sealed volume 182 and the first bypass device 172 acting on the compensation piston 164, 170 can create a pressure differential between the first flow passage and the sealed volume 182 by increasing a pressure in the sealed volume 182 by a constant amount above a pressure in the first flow passage 80, 176 . The increased pressure in the sealed volume 182 may create a pressure differential across the rotary actuator 120, thereby creating portion of the engagement force 97, 98, 99. The first flow passage 80, 176 may be an internal flow passage 80 of a drill string 30.

[0059] Valve 110 may include a screen 112 configured to filter fluid flowing from an internal flow passage 80 of a drill string 30 to the rotary valve 110, wherein the first flow passage 80, 176 is a chamber 176 which is downstream of the screen 112. The screen 112 may create a pressure drop in the screen 112 when fluid flows from an internal flow passage 80 of the drill string 30 into the chamber 176, so that the pressure in the chamber 176 is less than the pressure in the internal flow passage 80. The screen 112 may be configured to filter fluid flowing from a first external flow passage 80 to the rotary valve 110 to a chamber 176 in the rotary valve 110 that is downstream of the screen 112, wherein the screen 112 can create a pressure drop across the screen 112 when fluid flows from the first flow passage 80 to the chamber 176, such that the pressure in the chamber 176 is less than the pressure in the first flow passage 80. The valve 110 may include a sealed volume 182 within the valve housing 64, where a compensating piston 164, 170 may provide pressure communication between the sealed volume 182 and the first flow passage 80, 176. The pressure drop can create the pressure differential across the rotary actuator 120, thereby creating at least a portion of the engagement force 97, 98, 99.

[0060] A portion of the engagement force 97, 98, 99 may be created by the second deflection device 174 acting on the rotary actuator 120. A motor 69 with a drive shaft 68 may be coupled to the rotary actuator 120 through the a splined shaft 106 with a splined hub 104, wherein the splined hub 104 permits longitudinal movement of the splined shaft 106 relative to the splined hub 104 and the splined hub 104 restricts the splined shaft 106 from rotating with the splined hub 104. The second device deflection device 174 may be positioned between the splined hub 104 and the splined shaft 106 and the second offset device 174 may apply a deflection force 98 to the splined shaft 106 which urges the splined shaft 106 to move longitudinally in the splined hub 104, thereby creating the part of the coupling force 97, 98, 99.

[0061] An end 122 of the rotary actuator 120 may include the first engaging surface 138, wherein the end 122 is made of a silicon carbide diamond (ScD) composite and the engaging force 97, 98, 99 maintains the engagement between the first and second engagement surfaces 138, 132 during one or more impacts on the rotary valve 110. Damage to either of the first and second engagement surfaces 138, 132 can be avoided when contact is maintained between the first and second engagement surfaces 138, 132. the second engagement surface 138, 132. The valve seat 130 may be made of a silicon carbide diamond (ScD) composite and the engagement force 97, 98, 99 may maintain contact between the first and second engagement surfaces. engagement 138, 132 during one or more impacts on the rotary valve 110.

[0062] A system for directing a drill bit 102 with a rotary valve 110 is also provided and may include a downhole tool 100 interconnected in a drill string 30, the downhole tool 100 including a plurality of extendable pads 152A - C that can be activated by respective actuators 52A-C and the rotary valve 110 can selectively activate actuators 52A-C. The rotary valve 110 may include a valve housing 64, a manifold 62, a rotary actuator 120 with a first engagement surface 138, a valve seat 130 with a second engagement surface 132, and an engagement force 97, 98, 99 applied to the rotary actuator 120, wherein the engagement force 97, 98, 99 can maintain engagement between the first and second engagement surfaces 138, 132 and an interconnected drill bit 102 at the end of the drill string 30, wherein the drill bit 102 is steered due to the selective extension and retraction of the extendable pads 152A-C controlled by the rotary valve 110.

[0063] For any of the preceding embodiments, the system may include any of the following elements, individually or in combination with each other: At least one of the valve seats 130 and a portion of the rotary actuator 120 may be made of a composite Silicon Carbide Diamond (ScD).

[0064] The rotary valve 110 may include a motor 69 that controls the rotation of the rotary actuator 120, thereby causing selective extension and retraction of the extendable pads 152A-C. The motor 69 may be coupled to the rotary actuator 120 via a splined shaft 106 inserted into a splined hub 104, where the splined shaft 106 may move longitudinally within the splined hub 104.

[0065] The engagement force 97, 98, 99 may be partially created by at least one of a first bypass device 172, a second bypass device 174, and a pressure differential across the rotary actuator 120.

[0066] The rotary valve 110 may include a sealed volume 182, wherein the first bypass device 172 applies a compensating pressure to the sealed volume 182 and maintains the sealed volume 182 at an elevated pressure, wherein the elevated pressure is raised above of a flow passage pressure 80, 176 by the amount of compensation pressure and the flow passage 80, 176 is external to the sealed volume 182. The sealed volume 182 may contain an engine 69 and may be filled with clean oil 186, where clean oil 186 is maintained at high pressure. The elevated pressure of the clean oil 186 can produce at least a portion of the engagement force 97, 98, 99, creating a pressure differential across the rotary actuator 110.

[0067] The second deflection device 174 may be positioned between a splined hub 104 and a splined shaft 106 and the second deflection device 174 may act on the splined shaft 106 to produce at least a portion of the engagement force 97, 98, 99 .

[0068] Fluid 77 entering the rotary valve 110 from a flow passage 80 of the drill string 30 may pass through a screen 112 which may create a pressure drop in the fluid 77 that causes a pressure differential across the rotary actuator 120 and produces at least a portion of the engagement force 97, 98, 99.

[0069] A method for maintaining engagement between surfaces 138, 132 on a rotary valve 110 is also provided and may include mounting a rotary valve 110 on a downhole tool 100, where the rotary valve 110 may include a valve housing 64, a manifold 62, a rotary actuator 120 with a first engagement surface 138, and a valve seat 130 with a second engagement surface 132. Applying an engagement force 97, 98, 99 to the rotary actuator 120 , thus maintaining engagement between the first and second engagement surfaces 138, 132.

[0070] For any of the above embodiments, the system may include any of the following elements, individually or in combination with each other: Rotary valve 110 may include a compensating piston 164, 170 and a sealed volume 182, wherein The compensation piston 164, 170 provides pressure communication between the sealed volume 182 and a flow passage 80, 176 external to the sealed volume 182. Bypassing the compensation piston 164, 170 with a bypass device 172 can raise the pressure in the sealed volume 182 by an amount of compensation pressure above the pressure in the external flow passage 80, 176. Creating a pressure differential across the rotary actuator 120 due to the elevated pressure in the sealed volume 182 and producing at least a portion of the force coupling 97, 98, 99 due to high pressure.

[0071] The rotary valve 110 may include a transmission shaft 68 coupled to the rotary actuator 120 through a splined shaft 106 inserted into a splined hub 104, where a bypass device 174 may be positioned between the splined hub 104 and the splined shaft. 106. At least a portion of the engagement force 97, 98, 99 may be produced by the deflection device 174.

[0072] The rotary valve 110 may include a screen 112, wherein fluid 77 flowing through the screen 112 creates a pressure drop in the fluid flow and at least a portion of the engagement force 97, 98, 99 is produced by the pressure drop in the flowing fluid. The engagement force 97, 98, 99 may be realized at the surface 16 and/or at the bottom of the wellbore 12. Although various embodiments have been shown and described, the disclosure is not limited to such embodiments and it will be understood that it includes all modifications and variations, as would be evident to one skilled in the art. Therefore, it should be understood that disclosure is not intended to be limited to the particular forms disclosed; rather, the intent is to cover all modifications, equivalents and alternatives that fall within the spirit and scope of the disclosure as defined by the appended claims.

Claims (19)

1. Rotary valve (110), characterized by the fact that it comprises: a valve housing (64); a manifold (62) mounted in the valve housing (64); a rotary actuator (120) rotatably mounted within the valve housing (64), with the rotary actuator (120) having a first engagement surface (138); and a valve seat (130) which is coupled to the manifold (62), the valve seat (130) having a second engagement surface (132) which sealably engages the first engagement surface (138), wherein a engagement force (97, 98, 99) is applied to the rotary actuator (120) to maintain engagement between the first and second engagement surfaces (138, 132), wherein at least a portion of the engagement force (97, 98, 99) is created by a first bypass device (172) acting on a compensation piston (164, 170). 2. Valve (110) according to claim 1, characterized in that the engagement force (97, 98, 99) is created by at least one of a second bypass device (174) and a pressure differential across of the rotary actuator (120); and wherein the manifold (62) includes a plurality of flow paths, wherein the valve seat (130) further comprises ports (140A-C) that are in fluid communication with the respective flow paths in the manifold (62), and wherein that the rotary actuator (120) further comprises a space (116) that selectively aligns with respective valve seat ports (140A-C) as the rotary actuator (120) rotates relative to the valve seat (130). . 3. Valve (110) according to claim 1, characterized in that it further comprises a sealed volume (82) within the valve housing (64), wherein the compensation piston (164, 170) provides pressure communication between the sealed volume (82) and a first flow passage (80, 176) external to the sealed volume (82), and wherein the first bypass device (172) acting on the compensation piston (164, 170) creates a pressure differential between the first flow passage (80, 176) and the sealed volume (82) increasing a pressure in the sealed volume (82) by a constant amount above a pressure in the first flow passage (80, 176); wherein the increased pressure in the sealed volume (82) creates a pressure differential across the rotary actuator (120), thereby creating portion of the engagement force (97, 98, 99); wherein the first flow passage (80, 176) is an internal flow passage of a drill string (30); wherein the valve further comprises a screen (112) configured to filter fluid flowing from an internal flow passage of a drill string to the rotary valve (110), wherein the first flow passage is a chamber (176) that is downstream of the screen (112); and wherein the screen (112) creates a pressure drop across the screen (112) when fluid flows from an internal flow passage (80) of the drill string (30) to the chamber (176) such that the pressure in the chamber (176) is less than the pressure in the internal flow passage (80). 4. Valve (110) according to claim 2, characterized in that it further comprises a screen (112) configured to filter fluid flowing from a first flow passage external to the rotary valve (110) into a chamber (176) on the rotary valve (110) which is downstream of the screen (112), wherein the screen (112) creates a pressure drop across the screen (112) when fluid flows from the first flow passage into the chamber (176) so that the pressure in the chamber (176) is lower than the pressure in the first flow passage (80). 5. Valve (110) according to claim 4, characterized in that it further comprises a sealed volume (82) within the valve housing (64), wherein a compensating piston (164, 170) provides pressure communication between the sealed volume (82) and the first flow passage (80, 176); and/or wherein the pressure drop creates the pressure differential across the rotary actuator (120), thereby creating at least a portion of the engagement force (97, 98, 99). 6. Valve (110) according to claim 2, characterized by the fact that at least a portion of the engagement force (97, 98, 99) is created by the second bypass device (174) acting on the rotary actuator (120 ); further comprising a motor (69) with a transmission shaft (68) coupled to the rotary actuator (120) through engagement of a splined shaft (106) with a splined hub (104), wherein the splined hub (104) allows the longitudinal movement of the splined shaft (106) relative to the splined hub (104), and wherein the splined hub (104) restricts the splined shaft (106) from rotating with the splined hub (104); and wherein the second deflection device (174) is positioned between the splined hub (104) and the splined shaft (106), and the second deflection device (174) applies a deflection force to the splined shaft (106) which impels the splined shaft (106) moving longitudinally in the splined hub (104), thus creating the portion of the engagement force (97, 98, 99). 7. Valve (110) according to claim 1, characterized in that an end (122) of the rotary actuator (120) includes the first engaging surface (138), wherein the end (122) is made of a silicon carbide diamond (ScD) composite, and wherein the engagement force (97, 98, 99) maintains engagement between the first and second engagement surfaces (138, 132) during one or more impacts on the rotary valve (110); and wherein damage to one of the first and second engaging surfaces (138, 132) is prevented when contact is maintained between the first and second engaging surfaces (138, 132). 8. Valve (110) according to claim 1, characterized by the fact that the valve seat (130) is made of a silicon carbide diamond (ScD) composite, and wherein the engagement force (97. 98, 99) maintains contact between the first and second engagement surfaces (138, 132) during one or more impacts on the rotary valve (110); and wherein damage to one of the first and second engaging surfaces (138, 132) is prevented when contact is maintained between the first and second engaging surfaces (138, 132). 9. System for directing a drill bit with a rotary valve (110), characterized in that it comprises: a downhole tool (100) interconnected in a drill string (30), the downhole tool ( 100) comprising: a plurality of extendable pads (152A-C) which are activated by respective actuators, and the rotary valve (110) which selectively activates the actuators, the rotary valve (110) comprising: a valve housing (64), a manifold (62), a rotary actuator (120) with a first engagement surface (138), a valve seat (130) with a second engagement surface (132), and an engagement force (97, 98, 99) applied to the rotary actuator (120), wherein the engagement force (97, 98, 99) maintains engagement between the first and second engagement surfaces (138, 132), wherein at least a portion of the engagement force (97 , 98, 99) is created by a first bypass device (172) acting on a compensation piston (164, 170); and the drill bit interconnected at one end of the drill string, wherein the drill bit is directed due to the selective extension and retraction of the extendable pads (152A-C) which are controlled by the rotary valve (110). 10. System according to claim 9, characterized by the fact that at least one of the valve seat (130) and at least a portion of the rotary actuator (120) are made of a silicon carbide diamond (ScD) composite. . 11. System according to claim 9, characterized by the fact that the rotary valve (110) further comprises a motor (69), and wherein the motor (69) controls the rotation of the rotary actuator (120) and, thus, the selective extension and retraction of the extendable pads (152A-C); wherein the motor (69) is coupled to the rotary actuator (120) by means of a splined shaft (106) inserted into a splined hub (104), and wherein the splined shaft (106) can move longitudinally within the splined hub (104). 12. System according to claim 9, characterized by the fact that the engagement force (97, 98, 99) is at least partially created by at least one of a second bypass device (174) and a pressure differential across of the rotary actuator (120). 13. System according to claim 12, characterized by the fact that the rotary valve (110) further comprises a sealed volume (82), wherein the first bypass device (172) applies a compensation pressure to the sealed volume (82 ) and maintains the sealed volume (82) at an elevated pressure, wherein the elevated pressure is raised above a flow passage pressure by the amount of compensation pressure, and wherein the flow passage is external to the sealed volume (82 ). 14. System according to claim 13, characterized by the fact that the sealed volume (82) contains a motor and is filled with clean oil, and in which the clean oil is maintained at elevated pressure; and/or wherein the high pressure of the clean oil produces at least a portion of the engagement force (97, 98, 99) creating a pressure differential across the rotary actuator (120). 15. System according to claim 12, characterized by the fact that the second deflection device (174) is positioned between a splined hub (104) and a splined shaft (106), and wherein the second deflection device (174 ) acts on the splined shaft (106) to produce at least a portion of the engagement force (97, 98, 99); and/or wherein fluid entering the rotary valve (110) from a drill string flow passage passes through a screen (112) which creates a pressure drop in the fluid, and wherein this pressure drop causes a pressure differential across the rotary actuator (120) and thus produces at least a portion of the engagement force (97, 98, 99). 16. Method for maintaining engagement between surfaces in a rotary valve (110), characterized in that the method comprises: mounting a rotary valve (110) on a downhole tool, the rotary valve (110) comprising: a valve housing (64), a manifold (62), the rotary actuator (120) with a first engagement surface (138), and a valve seat (130) with a second engagement surface (132); and applying an engagement force (97, 98, 99) to the rotary actuator (120), thereby maintaining engagement between the first and second engagement surfaces (138, 132), wherein at least a portion of the engagement force ( 97, 98, 99) is created by a first bypass device (172) acting on a compensation piston (164, 170). 17. Method according to claim 16, characterized in that the rotary valve (110) further comprises a compensation piston (164, 170) and a sealed volume (82), and wherein the compensation piston (164, 170) 170) provides pressure communication between the sealed volume (82) and a flow passage (80, 176) external to the sealed volume (82); further comprising deflecting the compensation piston (164, 170) with a bypass device, thereby raising the pressure in the sealed volume (82) by an amount of compensation pressure above the pressure in the external flow passage; and further comprising creating a pressure differential across the rotary actuator (120) due to the elevated pressure in the sealed volume (82) and producing at least a portion of the engagement force due to the elevated pressure. 18. Method according to claim 16, characterized by the fact that the rotary valve (110) further comprises a transmission shaft coupled to the rotary actuator (120) by means of a splined shaft (106) inserted into a splined hub (104 ), and wherein a deflection device is positioned between the splined hub (104) and the splined shaft (106); and further comprising producing at least a portion of the engagement force (97, 98, 99) due to the deflection device. 19. Method according to claim 16, characterized in that the rotary valve (110) further comprises a screen (112), wherein the fluid flowing through the screen (112) creates a pressure drop in the fluid flow , and wherein at least a portion of the engagement force (97, 98, 99) is produced by the pressure drop in the fluid flow; and/or in which the application of the engagement force (97, 98, 99) is carried out at the surface and/or at the bottom of the well in a well.