Bias control unit

Abstract

A control unit includes a rotatable tubular body that rotates about a spindle. A torque transfer unit can be attached to the tubular body and the spindle. A force applied to the torque transfer unit by a biasing element can control a first torque applied by the tubular body to the spindle. The first torque is independent of the rotational speed of the tubular body. A second torque is applied to the spindle by a torque generator, the second torque controlling a net torque. Controlling the net torque allows controlling the absolute orientation of the control unit.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 62 / 850,680, filed May 21, 2019, entitled “Biased Control Unit,” the disclosure of which is incorporated herein by reference. Background Art

[0003] Wellbores may be drilled into a surface location or seabed for a variety of exploration or production purposes. For example, wellbores may be drilled to obtain fluids stored in underground formations, such as liquid and gaseous hydrocarbons, and to produce fluids from the formations. Wellbores used to produce or produce fluids may be lined with casing around the wellbore walls. A variety of drilling methods may be utilized, depending in part on the characteristics of the formations through which the wellbore is drilled.

[0004] A wellbore may be drilled by a drilling system that drills downward from the surface through earthen materials. Some wellbores are drilled vertically downward, and some wellbores have one or more bends in the wellbore to follow ideal geological formations, avoid problematic geological formations, or a combination of the two. Summary of the invention

[0005] In some embodiments, a control unit may include: a spindle; a tubular body rotatable relative to the spindle; and a torque transfer unit attached to the spindle and the tubular body. A biasing element may maintain a force against the torque transfer unit so that a first torque independent of a rotational speed of the tubular body may be applied to the spindle. A torque generator may be used to apply a second torque to the spindle to control a net torque on the spindle.

[0006] In other embodiments, a method for biasing a control unit may include rotating a tubular body connected to a torque transfer unit at a certain rotational speed. The torque transfer unit may apply a first torque to a spindle, the first torque being dependent on a force applied to the torque transfer unit using a biasing element. A second torque may be applied to the spindle using a torque generator, the second torque being used to control the net torque.

[0007] In yet other embodiments, a method for biasing a control unit may include flowing a first flow of drilling fluid through the control unit, causing the tubular body to rotate at a first speed and transmitting a first torque to the main shaft through a torque transmission unit. A torque generator may be used to apply a second torque to the main shaft. A second flow may flow through the control unit, the second flow having different fluid properties than the first flow, causing the tubular body to rotate at a second speed. The torque transmitted to the main shaft may remain the same for both the first speed and the second speed.

[0008] The provision of this summary is to introduce a series of concepts that are further described in the detailed description. This summary is not intended to identify the key or essential features of the claimed subject matter, nor is it intended to be used to assist in limiting the scope of the claimed subject matter. Other features and advantages of the embodiments of the present disclosure will be set forth in the following description, and will become apparent in part from the description, or may be learned by the practice of such embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to describe the manner in which the above-described and other features of the present disclosure can be obtained, a more specific description will be presented by reference to specific embodiments of the present disclosure, which are shown in the accompanying drawings. For better understanding, the same elements have been represented by the same reference numerals throughout the various drawings. Although some of the drawings may be schematic or exaggerated representations of concepts, at least some of the drawings may be drawn to scale. After understanding that the drawings depict some exemplary embodiments, the embodiments will be described and explained with additional features and details through the use of the drawings, in which:

[0010] Figure 1 is a schematic diagram of a general drilling station according to at least one embodiment of the present disclosure;

[0011] FIG2 is a representation of a prior art bias control unit;

[0012] Figure 3 is a perspective view of a control unit according to at least one embodiment of the present disclosure;

[0013] Figure 4 According to at least one embodiment of the present disclosure Figure 3 A longitudinal cross-sectional view of a control unit;

[0014] Figure 5 is a graph of the relationship between force and torque according to at least one embodiment of the present disclosure;

[0015] Figure 6 is a longitudinal cross-sectional view of another control unit according to at least one embodiment of the present disclosure;

[0016] Figure 7 is a longitudinal cross-sectional view of a movable nosepiece on a control unit according to at least one embodiment of the present disclosure;

[0017] Figure 8 is a method diagram of a method of biasing a control unit according to at least one embodiment of the present disclosure;

[0018] Fig. 9 According to at least one embodiment of the present disclosure Figure 8Another method diagram of the method of ; and

[0019] Fig.10 is yet another method diagram of a method of biasing a control unit according to at least one embodiment of the present disclosure. DETAILED DESCRIPTION

[0020] The present disclosure generally relates to apparatus, systems, and methods for biasing a control unit. Figure 1 One example of a drilling system 100 for drilling into an earth formation 101 to form a wellbore 102 is shown. The drilling system 100 includes a drilling rig 103 for rotating a drill assembly 104 that extends downwardly into the wellbore 102. The drill assembly 104 may include a drill string 105, a bottom hole assembly ("BHA") 106, and a drill bit 110 attached to the downhole end of the drill string 105.

[0021] The drill string 105 may include several joints of drill pipe 108a connected end to end by tool joints 109. The drill string 105 transmits drilling fluid through a central orifice and transmits rotational power from the drilling rig 103 to the BHA 106. In some embodiments, the drill string 105 may also include additional components, such as short sections, short drill pipes, etc. The drill pipe 108 provides hydraulic passages through which drilling fluid is pumped from the surface. The drilling fluid is discharged through nozzles, jets, or other orifices of selected sizes in the drill bit 110 for cooling the drill bit 110 and the cutting structure thereon and for lifting drill cuttings out of the wellbore 102 while drilling.

[0022] The BHA 106 may include a drill bit 110 or other components. An exemplary BHA 106 may include additional or other components (e.g., coupled between the drill string 105 and the drill bit 110). Examples of additional BHA components include drill collars, stabilizers, measurement while drilling (“MWD”) tools, logging while drilling (“LWD”) tools, downhole motors, underreamers, cross-sectioning shoes, hydraulic disconnects, jars, vibration or damping tools, other components, or combinations thereof.

[0023] Typically, the drilling system 100 may include other drilling components and accessories, such as special valves (e.g., kelly valves, blowout preventers, and safety valves). The additional components included in the drilling system 100 may be considered part of the drill string 104, the drill string 105, or the BHA 106, depending on their location in the drilling system 100.

[0024] The drill bit 110 in the BHA 106 can be any type of drill bit suitable for stripping downhole materials. For example, the drill bit 110 can be a drill bit suitable for drilling the formation 101. Exemplary types of drill bits used to drill the formation are fixed cutter or drag bits. In other embodiments, the drill bit 110 can be a milling shoe for removing metals, composites, elastomers, other downhole materials, or combinations thereof. For example, the drill bit 110 can be used with a whipstock to mill into a casing 107 lining the wellbore 102. The drill bit 110 can also be a flat-head milling shoe for milling out tools, plugs, cement, other materials, or combinations thereof within the wellbore 102. Chips or other drill cuttings formed using the milling shoe may be lifted to the surface or may be allowed to fall downhole.

[0025] FIG. 2 shows a schematic diagram of a BHA (such as Figure 1 1 and 10. The control unit 214 may be located inside the instrument carrier 216. The control unit 214 may include an upper impeller 218 and a lower impeller 220. The upper impeller 218 includes a plurality of upper impeller fins 222-1, and the lower impeller 220 includes a plurality of lower impeller fins 222-2. The upper impeller fins 222-1 and the lower impeller fins 222-2 may be oriented so that the upper impeller 218 rotates in a different direction than the lower impeller 220.

[0026] The upper impeller 218 is coupled to an upper electric torque generator 224-1, which transmits torque from the rotation of the upper impeller 218 to the control unit 214. The lower impeller 220 is also coupled to a lower electric torque generator 224-2, which transmits torque from the rotation of the lower impeller 220 to the control unit 214. Because the upper impeller 218 and the lower impeller 220 rotate in different directions, opposite torques can be applied to the control unit 214. The amount of electrical load on the torque generators 224-1, 224-2 can be changed to change the torque applied to the control unit 214 by the upper impeller 218 and the lower impeller 220. Therefore, the orientation of the control unit 214 can be controlled by changing the electrical load applied to one or both of the torque generators 224-1, 224-2. In order to turn in a given direction, the control unit 214 can remain substantially stationary to the earth. The control unit 214 can then control a valve that allows flow (e.g., mud flow) to reach the pad of a unit (e.g., a bias unit) that steers by pushing against the formation as the bias unit rotates relative to the geostationary control unit 214 and the valve. The steering direction can then be changed by changing the orientation of the control unit 214. Any suitable type of bias unit can be used.

[0027] In some cases, the bearings and other spaces of one or both of the upper impeller 218 and the lower impeller 220 may be filled with debris, thereby increasing the chances of impeller wear and jamming (e.g., biting and stopping rotation). Therefore, it may be desirable for the control unit to include only one (e.g., a single) rotating component as described herein. In some cases, this can improve downhole reliability, which can increase drilling speed and reduce overall drilling costs. In some embodiments, one of the upper impeller or the lower impeller can be replaced with other features as will be described herein, which reduce or alleviate the jamming problems sometimes observed when using the impeller. In some embodiments, the upper impeller can generate electricity for the control unit and apply torque in a first direction, and the lower torquer can be replaced by a torque transfer unit that uses friction to apply friction in a second direction opposite to the first direction.

[0028] Figure 3 is a perspective view of a control unit 314 according to at least one embodiment of the present disclosure. In some embodiments, the control unit 314 can be configured to be positioned on a drill rod (e.g., Figure 1 of drill pipe 108) and / or a BHA (e.g., Figure 1 The control unit 314 includes a tubular body 318. In some embodiments, the tubular body 318 can be or include an impeller. For example, the tubular body 318 can have a plurality of fins 322. The plurality of fins 322 can be oriented so that when drilling fluid flows through the control unit 314, the drilling fluid will hit the plurality of fins 322, thereby causing at least a portion of the tubular body 318 to rotate.

[0029] Figure 4 express Figure 3 The control unit 314. The tubular body 318 can be configured to rotate about a control unit axis 326. The control unit 314 also includes a main shaft 328, which is also configured to rotate about the control unit axis 326. In some embodiments, the tubular body 318 is the only tubular body 318 that rotates about the main shaft. In other words, the control unit 314 can include a single (e.g., no more than one) tubular body 318. The tubular body 318 may include a support member 330. The support member 330 may include one or more lips 332. The lip 332 can be oriented radially inward from the tubular body 318 or coaxial with the tubular body.

[0030] In some embodiments, the control unit 314 may be rotationally independent of the BHA (e.g., Figure 1In other words, the control unit 314 can be configured to rotate at a different speed than the surrounding BHA. In some embodiments, the control unit 314 can rotate independently of the drill bit (e.g., Figure 1 The drill bit 110 may be configured to rotate at a different speed than the drill bit.

[0031] In some embodiments, one or more torque transfer units 334-1, 334-2 can be attached to the main shaft 328 and the tubular body 318. The torque transfer unit 334-1, 334-2 can extend around the circumference of the main shaft 328 and include a first member 336-1, 336-2 attached to the main shaft 328 and a second member 338-1, 338-2 attached to the tubular body 318. In some embodiments, the second member 338-1, 338-2 can be attached to the tubular body 318 at the lip 332. The first member 336-1, 336-2 has a first bearing surface 340-1, 340-2, and the second member 338-1, 338-2 has a second bearing surface 342-1, 342-2. The first bearing surface 340-1, 340-2 abuts or contacts the second bearing surface 342-1, 342-2. In the illustrated embodiment, the first bearing surfaces 340-1, 340-2 and / or the second bearing surfaces 342-1, 342-2 can be oriented perpendicular to the main axis 328. For example, the first bearing surfaces 340-1, 340-2 and / or the second bearing surfaces 342-1, 342-2 can be oriented perpendicular to the control unit axis 326 of the control unit 314. When the torque transfer units 334-1, 334-2 are stationary relative to each other, a static friction coefficient exists between the first bearing surfaces 340-1, 340-2 and the second bearing surfaces 342-1, 342-2. When the torque transfer units 334-1, 334-2 move or rotate relative to each other, a dynamic friction coefficient exists between the first bearing surfaces 340-1, 340-2 and the second bearing surfaces 342-1, 342-2.

[0032] In some embodiments, the control unit 314 may include two torque transfer units: an upper torque transfer unit 334-1 and a lower torque transfer unit 334-2. In some embodiments, the torque transfer units 334-1 and 334-2 may be positioned adjacent to or close to each other. The upper second member 338-1 is separated from the lower second member 338-2 by a certain separation distance 343. In some embodiments, the separation distance 343 may be within a range having an upper limit value, a lower limit value, or an upper limit value and a lower limit value including any one of 0.1 cm, 0.2 cm, 0.4 cm, 0.6 cm, 0.8 cm, 1.0 cm, 2.0 cm, 3.0 cm, 4.0 cm, 5.0 cm, 6.0 cm, 7.0 cm, 8.0 cm, 9.0 cm, 10.0 cm, or any value therebetween. For example, the separation distance 343 may be greater than 0.1 cm. In another example, the separation distance 343 may be less than 10.0 cm. In yet other examples, the separation distance 343 can be any value in the range between 0.1 cm and 10.0 cm. In some embodiments, the separation distance 343 can be equal to the thickness of the lip 332. In other embodiments, the separation distance 343 can be greater than the thickness of the lip 332. In some embodiments, the separation distance between 6.0 cm and 10.0 cm may be critical. The separation distance 343 may be sufficient to place the hub aero foil section in the space between the upper second member 338-1 and the lower second member 338-2.

[0033] In some embodiments, the tubular body 318 may include more than one lip 332 attached to more than one pair of torque transfer units 334-1, 334-2. For example, the tubular body 318 may include two lips attached to four torque transfer units. In another example, the tubular body 318 may include three lips attached to six torque transfer units.

[0034] In other embodiments, the control unit 314 may include one torque transfer unit. In still other embodiments, the control unit 314 may include 3, 4, 5, or 6 torque transfer units.

[0035] As the tubular body 318 rotates, the second bearing surfaces 342-1, 342-2 can slide along the first bearing surfaces 340-1, 340-2. Therefore, in some embodiments, the torque transmission unit 334-1, 334-2 can be an axial bearing. In some embodiments, the first bearing surface 340-1, 340-2 and the second bearing surface 342-1, 342-2 can be made of tungsten carbide (WC). In other embodiments, the first bearing surface 340-1, 340-2 and the second bearing surface 342-1, 342-2 can be made of polycrystalline diamond (PCD). In yet other embodiments, the first bearing surface 340-1, 340-2 and the second bearing surface 342-1, 342-2 can be made of any wear-resistant material such as silicon carbide or cubic boron nitride.

[0036] In some embodiments, the first bearing surface 340-1, 340-2 and the second bearing surface 342-1, 342-2 can be made of the same material. For example, both the first bearing surface 340-1, 340-2 and the second bearing surface 342-1, 342-2 can be made of PCD. In other examples, the first bearing surface 340-1, 340-2 and the second bearing surface 342-1, 342-2 can be made of WC.

[0037] In other embodiments, the first bearing surface 340-1, 340-2 and the second bearing surface 342-1, 342-2 can be made of different materials. For example, the first bearing surface 340-1, 340-2 can be made of PCD, and the second bearing surface 342-1, 342-2 can be made of WC. In other examples, the first bearing surface 340-1, 340-2 can be made of WC, and the second bearing surface 342-1, 342-2 can be made of PCD. In still other embodiments, one or more torque transfer units 334-1, 334-2 may include relative disks, each disk having a PCD button ring mounted on a matching surface. Each PCD button ring can be aligned in an equidistant circular pattern, and each ring has a different number of equidistant PCD buttons so that all PCD buttons never completely overlap each other. The bearing surfaces of each ring (eg, first bearing surfaces 340-1, 340-2 and second bearing surfaces 342-1, 342-2) may be milled so that the PCD surface of each button is at the same height when measured from the surface of the disc. However, any suitable bearing may be used.

[0038] In some embodiments, one or more torque transfer units 334-1, 334-2 may be thrust bearings including a polycrystalline diamond surface.The material combination on the first bearing surface 340-1, 340-2 and the second bearing surface 342-1, 342-1 may contribute to the static and kinetic coefficients of friction.

[0039] The biasing element 344 can be connected to the main shaft 328. In some embodiments, the biasing element 344 can include an elastic member 346 biased against the lower torque transfer unit 334-2. Or, in other words, the biasing element 344 can apply a force to the lower first member 336-2. In other words, the biasing element 344 can maintain the position of the first member 336-1, 336-2 against the second member 338-1, 338-2. The force applied to the lower first member 336-2 can be transferred to the lower second member 338-2. The lower second member 338-2 can transfer the force to the lip 332 of the tubular body 318, and the lip can transfer the force to the upper second member 338-1. Then the force can be transferred from the upper second member 338-1 to the upper first member 336-1.

[0040] In embodiments including more than two torque transfer units 334-1, 334-2 (e.g., more than one lip 332 on the tubular body 318), each torque transfer unit 334-1, 334-2 may include its own biasing element 344. In other embodiments, each torque transfer unit pair (such as an upper torque transfer unit 334-1 and a lower torque transfer unit 334-2) may include a biasing element 344. In still other embodiments, the biasing element 344 may apply a force through more than two torque transfer units 334-1, 334-2.

[0041] In some embodiments, the upper first member 336-1 can be rigidly attached to the main shaft 328 both longitudinally and rotationally. Therefore, the force applied by the biasing element 344 can be applied to the upper first member 336-1. The force can clamp the torque transfer unit 334-1, 334-2 between the biasing element 344 and the upper first member 336-1. A greater force applied to the torque transfer unit 334-1, 334-2 will result in greater static friction and greater dynamic friction. Therefore, the static friction and dynamic friction depend on the force applied to the torque transfer unit 334-1, 334-2 and the static friction coefficient and the dynamic friction coefficient.

[0042] In some embodiments, the resilient member 346 can be a conical or frustoconical washer, such as a Belleville spring. In other embodiments, the resilient member 346 can be a coil spring, a leaf spring, or any other type of member configured to apply a force against the lower first member 336-2. In still other embodiments, the resilient member 346 can be a piston, such as a hydraulic or pneumatic piston. The hydraulic or pneumatic piston can make it possible to change the force applied by the biasing element 344 during operation.

[0043] In some embodiments, the position of the biasing element 344 can be changed along the length of the main shaft 328. Changing the position of the biasing element 344 can change the force applied by the elastic member 346 against the lower first member 336-2. Or, in other words, changing the position of the biasing element 344 on the main shaft 328 can change the force applied to the torque transfer unit 334-1, 334-2. For example, moving the biasing element 344 closer to the lower first member 336-2 can increase the force applied against the lower first member 336-2, thereby increasing static friction and dynamic friction. In other examples, moving the biasing element 344 farther away from the lower first member 336-2 can reduce the force applied against the lower first member 336-2, thereby reducing static friction and dynamic friction.

[0044] In some embodiments, the biasing element 344 can be mounted on the spindle 328 using a threaded connection. By rotating the biasing element 344 on the threaded connection, the longitudinal position of the biasing element 344 can be changed, and thus the force applied to the torque transfer unit 334-1, 334-2 can be changed. In this way, the static friction coefficient and the dynamic friction coefficient can be changed by moving the biasing element 344 on the threaded connection.

[0045] In some embodiments, the lower first member 336-2 can be longitudinally slidably attached to the main shaft 328. Or, in other words, the lower first member 336-2 can slide along the main shaft 328 parallel to the control unit axis 326 but remain fixed to the main shaft 328 in rotation. This can be achieved, for example, by one or more dovetail type connections between the inner surface of the lower first member 336-2 and the outer surface of the main shaft 328. Having a longitudinally slidable connection at the lower first member 336-2 can allow the force from the biasing element 344 to be more fully transmitted to the remaining components of the torque transfer unit 334-1, 334-2. In some embodiments, the tubular body 318 can be longitudinally fixed or held in place by the force applied by the biasing element 344.

[0046] In other embodiments, the biasing element 344 can be mounted on the main shaft 328 between the torque transfer units 334-1, 334-2. The upper second member 338-1 and the lower second member 338-2 can be slidably attached to the main shaft 328. Or, in other words, the upper second member 338-1 and the lower second member 338-2 can slide along the main shaft 328 parallel to the control unit axis 326 but remain fixed to the main shaft 328 in rotation. This can be achieved, for example, by one or more dovetail connections between the inner surface of the upper second member 338-1 and the lower second member 338-2 and the outer surface of the main shaft 328. Having a longitudinally slidable connection at the upper second member 338-1 and the lower second member 338-2 can allow the force from the biasing element 344 to be more fully transmitted to the remaining members of the torque transfer units 334-1, 334-2 (e.g., the upper first member 336-1 and the lower first member 336-2). In some embodiments, the tubular body 318 can be longitudinally fixed or held in place by the force applied by the biasing element 344.

[0047] The impact of the drilling fluid on the plurality of fins 322 on the tubular body 318 can apply torque to the tubular body 318. The tubular body 318 can transmit torque to the first member 336-1, 336-2. The torque will push the first bearing surface 340-1, 340-2 to slide against the second bearing surface 342-1, 342-2, or in other words, the torque will push the first member 336-1, 336-2 to rotate relative to the second member 338-1, 338-2. When the torque reaches the breakout torque, the first bearing surface 340-1, 340-2 will begin to slide against the second bearing surface 342-1, 342-2, or in other words, the first member 336-1, 336-2 will begin to rotate relative to the second member 338-1, 338-2. The breakout torque is the torque when the static friction force is overcome, and depends on the static friction coefficient and the static friction force. In other words, a higher static friction coefficient and / or static friction force will result in a higher breakaway torque. In other words again, a greater force applied by the biasing element 344 will result in a higher breakaway torque.

[0048] Different properties of the drilling fluid may affect the torque applied to the tubular body 318, and therefore the rotational speed of the tubular body 318. For example, a higher volume flow rate may increase the rotational speed, while a lower volume flow rate may decrease the rotational speed. A higher mud density may increase the force applied against the plurality of fins 322, thereby increasing the rotational speed, while a lower mud density may decrease the rotational speed. Other fluid properties include mud viscosity, mud composition (e.g., water-based, oil-based, chemical additives, or elemental additives), mud pressure, or other fluid properties.

[0049] When the first member 336-1, 336-2 rotates relative to the second member 338-1, 338-2, the second member 338-1, 338-2 will transfer the first torque 345 to the first member 336-1, 336-2, which will transfer the torque to the main shaft 328. Therefore, the tubular body 318 transfers the torque to the main shaft 328 through the torque transfer unit 334-1, 334-2. Due to the dynamic friction force, the first torque 345 is transferred through the torque transfer unit 334-1, 334-2. Higher dynamic friction forces will transfer more torque from the tubular body 318 to the main shaft 328, while lower dynamic friction forces will transfer less torque from the tubular body 318 to the main shaft 328.

[0050] In some embodiments, the first torque 345 may be within a range having an upper limit value, a lower limit value, or both, including any of 0.0 N·m, 0.5 N·m, 1.0 N·m, 1.5 N·m, 2.0 N·m, 2.5 N·m, 3.0 N·m, 3.5 N·m, 4.0 N·m, 4.5 N·m, 5.0 N·m, 6 N·m, 7 N·m, 8 N·m, 9 N·m, 10 N·m, or any value therebetween. In one example, the first torque 345 may be less than 5.0 N·m. In another example, the first torque 345 may be less than 10 N·m.

[0051] The first torque 345 may cause the spindle 328 to rotate at a spindle speed. The spindle speed may be different from the surrounding BHA (e.g., Figure 1 The control unit 314 may include a torque generator 348. The torque generator 348 may be configured to apply a second torque 347 against the main shaft 328. The second torque 347 may be opposite in direction to the first torque 345, or in other words, the second torque 347 may be a counter torque to the first torque 345. For example, if the first torque 345 is counterclockwise, the second torque 347 will be clockwise. Similarly, if the first torque 345 is clockwise, the second torque 347 will be counterclockwise.

[0052] The torque generator 348 may include any device configured to apply torque to the main shaft 328. In some embodiments, the torque generator 348 may be an electromagnetic brake. For example, the main shaft 328 may include a plurality of magnets placed circumferentially around the outer portion of the main shaft 328. A corresponding set of electromagnets may be positioned radially offset from the main shaft 328. In other examples, the main shaft 328 may include a plurality of electromagnets, and the permanent magnets may be radially offset from the main shaft 328. When an electrical load is applied to the electromagnets, the electromagnets and the magnets will interact, thereby generating a second torque 347 or a counter torque on the main shaft 328.

[0053] In other embodiments, the torque generator 348 can be a mechanical brake. For example, the torque generator 348 can be a band brake. In other examples, the torque generator 348 can be a disc brake. The spindle 328 can include a circumferential disc against which the caliper can be applied, thereby applying the second torque 347.

[0054] In some embodiments, the second torque 347 may be within a range having an upper limit value, a lower limit value, or an upper limit value and a lower limit value including any of 0.5 N m, 1.0 N m, 2.0 N m, 3.0 N m, 4.0 N m, 5.0 N m, 6.0 N m, 7.0 N m, 8.0 N m, 8.0 N m, 10.0 N m, 12.0 N m, 14 N m, 16 N m, 18 N m, 20 N m, 25 N m, 30 N m, 35 N m, 40 N m, 45 N m, 50 N m, or any value therebetween. For example, the second torque 347 may be greater than 0.5 N m. In another example, the second torque 347 may be less than 50 N m. In yet other examples, the second torque 347 may be any value within a range between 0.5 N m and 50 N m. In a further example, the second torque 347 may be in a range between 1.0 Nm and 14 Nm.

[0055] The first torque 345 and the second torque 347 can be related to each other. For example, the first torque 345 can transfer rotation from the tubular body 318 to the main shaft 328 to rotate the main shaft 328 in a first direction, while the second torque 347 can be oriented in the opposite rotational direction to counteract the rotation in the first direction. Therefore, the relative magnitudes of the first torque 345 and the second torque 347 can affect the absolute rotation of the main shaft 328 relative to the surrounding environment of the control unit 314.

[0056] In some embodiments, the first torque 345 and the second torque 347 may have the same first magnitude and second magnitude, respectively, and the first torque 345 and the second torque 347 may offset each other. In other embodiments, the second magnitude may be within 10% of the first magnitude. For example, the spindle 328 may be asymmetrically balanced relative to the control unit axis 326. In such examples, when the control unit 314 is located in a transverse borehole, the spindle 328 may be "stable" in a specific orientation relative to gravity. When the second magnitude offsets at least 80% of the first magnitude, gravity may be sufficient to keep the spindle 328 in a specific orientation. In yet other embodiments, the second magnitude may be within 5% of the first magnitude (i.e., offset at least 85% of the first magnitude). In further embodiments, the second magnitude may be within 1% of the first magnitude (i.e., offset at least 89% of the first magnitude).

[0057] In some embodiments, the first torque 345 can remain constant above a minimum rotational speed of the tubular body 318. Or, in other words, the dynamic friction force can be independent of the rotational speed of the tubular body 318. Or, in yet other words, the first torque 345 is independent of the rotational speed of the tubular body 318 above the minimum rotational speed.

[0058] In some embodiments, the first torque 345 may fluctuate within a range having an upper limit, a lower limit, or both, including any of 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 8%, 10%, or any value therebetween. For example, the first torque 345 may fluctuate by more than 1%. In another example, the first torque 345 fluctuates by less than 10%. In yet other examples, the first torque 345 fluctuates by any value within the range of 1% to 10%.

[0059] In some embodiments, the minimum rotation speed may be within a range having an upper limit, a lower limit, or both, including any one of 0 revolutions per minute (RPM), 100RPM, 500RPM, 1,000RPM, 1,500RPM, 2,000RPM, 2,500RPM, 3,000RPM, 3,500RPM, 4,000RPM, 4,500RPM, 5,000RPM, or any value therebetween. For example, the minimum rotation speed may be any value within a range between 0RPM and 5,000RPM.

[0060] The particular torque transfer unit 334-1, 334-2 having first bearing surfaces 340-1, 340-2, second bearing surfaces 342-1, 342-2 made of known materials may dictate what the magnitude of the first bearing surface 345 may be for a given force. Figure 5 is a force applied to the torque transfer unit (such as by the biasing element 344 against Figure 4 The torque transfer units 334-1, 334-2 exert a force) and a torque (such as Figure 4 The graph indicates that the torque depends on the force applied against the torque transfer unit (e.g., by the biasing element 344 against the Figure 4 The relationship between torque and force is linear or approximately linear.

[0061] Because the torque remains constant or approximately constant, the torque of the Figure 4 The biasing element 344) exerts a given force on the spindle (e.g., Figure 4 The rotation of the main shaft 328) can be known. Or, in other words, for a given axial position of the biasing element, the rotation of the main shaft can be known.

[0062] A first torque (eg, Figure 4 The first torque 345) and the second torque (eg, Figure 4 The target net torque may be the net torque required to maintain a desired speed or a desired absolute orientation (e.g., orientation relative to north or relative to the direction of gravity). Because the first torque is known for a given force, it can be determined by using a torque generator (e.g., Figure 4 The torque generator 348 of the embodiment of the present invention changes the magnitude of the second torque to control the net torque. By controlling the rotation of the net torque, the main shaft and thus the control unit (e.g., Figure 4 Using the absolute orientation of the control unit, the rotary steerable system may be able to bias the drill bit in a desired direction. In this way, a tubular body (e.g., Figure 4 The orientation of the control unit is controlled by rotating the tubular body 318).

[0063] Figure 6 414 according to at least one embodiment of the present disclosure. The control unit 414 may include Figure 3 , Figure 4 and Figure 5 In some embodiments, the tubular body 418 may be rotatably or rigidly connected to a drill bit (e.g., Figure 1 In other words, the tubular body 418 can rotate at the same speed as the drill bit 106. In other embodiments, the tubular body 418 can rotate at the same speed as any other part of the BHA.

[0064] In some embodiments, the tubular body 418 can be connected to a torque transfer unit 434 having a first member 436 connected to the main shaft 428 and a second member 438 connected to the tubular body 418. The first member 436 has a first bearing surface 440, and the second member 438 has a second bearing surface 442. The second member 438 abuts the first member 436 so that the first bearing surface 440 is in contact with the second bearing surface 442. A biasing element 444 having an elastic member 446 can be biased against the second member 438, applying a force to the second member 438, which is transferred to the first member 436. A torque generator 448 can be connected to the main shaft 428. In some embodiments, the torque generator 448 can be connected to the main shaft 428 below the torque transfer unit 434 (e.g., downhole). In other embodiments, the torque generator 448 can be connected to the main shaft 428 above the torque transfer unit (e.g., uphole).

[0065] When the tubular body 418 rotates with the drill bit, the second member 438 will rotate relative to the first member 436. Figure 5 As discussed, when the tubular body 418 rotates beyond the minimum rotation speed, the first torque 445 will be transmitted to the main shaft 428 through the torque transmission unit 434. The second torque 447 opposite to the first torque 445 can be applied to the main shaft 428 from the torque generator 448. The net torque is the difference between the first torque 445 and the second torque 447.

[0066] The target net torque may be determined to keep the main shaft 428, and therefore the control unit 414, rotating at a particular speed. Because above the minimum speed, for a given force on the torque transfer unit 434, the first torque remains constant or approximately constant (see Figure 5 ), so the target net torque can be maintained by adjusting the torque generator 448. Therefore, the rotation speed of the control unit 414, and therefore the absolute orientation, can be maintained by adjusting the second torque 447 applied by the torque generator 448.

[0067] Figure 7 An embodiment of a system for regulating flow through a set of fins is shown. For example, the system can include a nose 592 located at an uphole end of a control unit 514. In some embodiments, the nose 592 can move in a longitudinal direction 594 relative to a sleeve 590 of the control unit 514. The sleeve 590 can accommodate the fins 522 and / or the tubular body 518 of the control unit 514 so that the tubular body 518 is rotated by a flow of drilling fluid 596 passing through the sleeve 590 between the sleeve 590 and the tubular body 518.

[0068] In some embodiments, the nose 592 is configured to selectively shield the inlet 598 of the sleeve 590. In other words, the nose 592 can be moved relative to the sleeve 590 in the longitudinal direction 594 to an open position and a closed position. In some embodiments, the nose 592 is passively biased toward the open position. When the flow 596 applies force to the nose 592 and pushes the nose 592 toward the sleeve 590, the nose 592 can move longitudinally toward the closed position. In other embodiments, the longitudinal position of the nose 592 is actively controlled. For example, the nose 592 can be moved by an electric motor or by a hydraulic or pneumatic piston and cylinder in response to a detected flow rate flowing through the tubular body 518 and / or in response to a detected torque applied to the tubular body 518.

[0069] In the open position, the nose 592 can be longitudinally positioned away from the inlet 598 and can allow a flow 596 of drilling fluid to enter the sleeve 590, thereby interacting with the fins 522 to move the tubular body 518. In the closed position, the nose 592 can close or otherwise shield the inlet 598 of the sleeve 590, such that the flow 596 entering the sleeve 590 is reduced relative to the flow 596 in the open position. In some embodiments, the nose 592 in the closed position blocks approximately all of the flow 596 from entering the sleeve 590. For example, the nose 592 can direct at least 85% of the flow 596 to the outside of the sleeve 590 when in the closed position relative to the flow 596 in the open position. In other embodiments, the nose can allow at least a portion of the flow 596 to enter the inlet 598 when in the closed position. For example, nose piece 592 may admit at least 10%, at least 20%, or at least 30% of flow 596 when in the closed position relative to flow 596 in the open position.

[0070] The movable nose 592 can adjust the flow 596 through the fins 522. Therefore, the nose 592 can adjust the torque applied to the tubular body 518 by the drilling fluid flow 596. The force applied to the fins 522 and therefore the torque applied to the tubular body 518 can be related to the flow rate, fluid density, viscosity or other properties of the drilling fluid flow 596. For example, the flow rate may increase, which may undesirably increase the torque on the tubular body. The nose 592 according to the present disclosure can move longitudinally toward the sleeve 590 in response to the increase in flow rate, thereby reducing the flow 596 through the inlet 598 to maintain a more constant torque on the tubular body 518. In other examples, the flow rate may remain unchanged, while the drilling fluid density may increase, which may undesirably increase the torque on the tubular body. A nose 592 according to the present disclosure can move longitudinally toward the sleeve 590 in response to an increase in drilling fluid density, thereby reducing flow 596 through the inlet 598 to maintain a more constant torque on the tubular body 518. In each case, the increase in flow rate and the increase in drilling fluid density apply an increased force to the nose 592, which can move the passively biased nose 592 in the longitudinal direction 594 to adjust the flow 596 through the sleeve 590. In other examples, the nose 592 can be actively moved in the longitudinal direction 594 by an electric motor or by a hydraulic or pneumatic piston and cylinder.

[0071] Figure 86 is a method diagram showing a method 670 for biasing a control unit. The method 670 includes rotating a tubular body at 672. In some embodiments, the tubular body may be rotated by passing drilling fluid through a plurality of fins. In other embodiments, the tubular body may rotate with the rotation of the drill bit. The tubular body rotates at a certain rotation speed. In some embodiments, the tubular body may rotate at a minimum rotation speed. The tubular body may be connected to a first member of a torque transfer unit, wherein a second member of the torque transfer unit is connected to a spindle coaxial with the tubular body.

[0072] At 674, a biasing element may be used to apply a force to a second member of the torque transfer unit. In some embodiments, at 676, a first torque may be applied to the main shaft through the torque transfer unit by rotation of the tubular body. The first torque may be applied by sliding the first member against the second member. In some embodiments, the first torque may depend on the force applied to the second member. In some embodiments, the first torque may be independent of a rotational speed greater than a minimum rotational speed. At 677, a torque generator may be used to apply a second torque to the main shaft.

[0073] Fig. 9 yes Figure 8 The method 670 of FIG. 1 further includes determining a net torque sufficient to maintain the absolute axial orientation at 678. The net torque is the difference between the first torque and the second torque. At 679, the net torque can be controlled by changing the second torque applied by the torque generator.

[0074] Fig.10 780 is shown for biasing a control unit. In some embodiments, at 782, a first stream of drilling fluid may flow through the control unit. The first stream may have a fluid property with a first value. The fluid property may be at least one of fluid density, fluid composition, fluid velocity, or fluid viscosity, or any combination of fluid properties. Flowing the first stream may cause the tubular body to rotate at a first rotational speed.

[0075] At 784, as a result of flowing the first flow, a first torque can be applied to the main shaft by the torque transfer unit. A first member of the torque transfer unit can be rigidly connected to the main shaft, and a second member of the torque transfer unit can be rigidly connected to the tubular body. Thus, when the first flow is caused to flow to rotate the tubular body, a first torque can be applied to the main shaft. In some embodiments, two torque transfer units connected to the lips of the tubular body can be used to apply the first torque.

[0076] At 786, a torque generator may be used to apply a second torque to the spindle. The second torque may be applied in a direction opposite to the first torque. This will produce a net torque, which is the difference between the first torque and the second torque. The net torque may be adjusted by changing or adjusting the second torque. In some embodiments, at 788, a second stream may flow through the control unit. The second stream may have different fluid properties from the first stream. Flowing the second stream may cause the tubular body to rotate at a second speed different from the first speed. For the first speed and the second speed, the first torque may maintain the same magnitude or have the same magnitude or approximately the same magnitude.

[0077] The embodiments of the control unit are described primarily with reference to wellbore drilling operations; the control unit described herein can be used in applications other than drilling wellbores. In other embodiments, the control unit according to the present disclosure can be used outside of a wellbore or other downhole environment for exploring or producing natural resources. For example, the control unit of the present disclosure can be used in a borehole for placing utility lines. Therefore, the terms "wellbore", "borehole", etc. should not be interpreted as limiting the tools, systems, assemblies, or methods of the present disclosure to any particular industry, field, or environment.

[0078] One or more specific embodiments of the present disclosure will be described herein. These described embodiments are examples of currently disclosed technology. In addition, in an effort to attempt to provide a concise description of these embodiments, all features of the actual embodiments may not be described in this specification. It should be understood that in the development of any such actual implementation, as in any engineering or design project, many implementation-specific decisions will be made to achieve the specific goals of the developer, such as compliance with system-related and business-related constraints, which may be different between different implementations. In addition, it should be understood that this development work may be complex and time-consuming, but for the general technicians who benefit from the present disclosure, they will be routine work in design, manufacture and production.

[0079] In addition, it should be understood that the reference to "one embodiment" or "embodiment" of the present disclosure is not intended to be interpreted as excluding the existence of other embodiments that also incorporate the features. For example, any element described with respect to the embodiments herein can be combined with any element of any other embodiment described herein. As will be understood by those of ordinary skill in the art encompassed by the embodiments of the present disclosure, the numerals, percentages, ratios, or other values ​​set forth herein are intended to include the value and other values ​​that are "about" or "approximately" the value. Therefore, the value should be interpreted broadly enough to include at least sufficiently close to the value to perform the desired function or achieve the desired result. The value includes at least the variation expected in a suitable manufacturing or production process, and may include values ​​within 5%, within 1%, within 0.1%, or within 0.01% of the value.

[0080] In view of this disclosure, those skilled in the art will recognize that equivalent constructions do not depart from the spirit and scope of the present disclosure, and that various changes, substitutions, and modifications may be made to the embodiments disclosed herein without departing from the spirit and scope of the present disclosure. Equivalent structures including functional "means plus function" clauses are intended to cover structures described herein as performing the functions described, including structural equivalents that operate in the same manner and equivalent structures that provide the same functions. Applicants expressly intend not to invoke means plus function or other functional claim protection for any claim other than those claims in which the words 'means for' appear together with the associated function. Every addition, deletion, and modification to the embodiments that falls within the meaning and scope of the claims will be covered by the claims.

[0081] As used herein, the terms "approximately," "about," and "substantially" refer to an amount that is close to a stated amount, is within standard manufacturing or process tolerances, or still performs a desired function or achieves a desired result. For example, the terms "approximately," "about," and "substantially" may refer to an amount that is within 5%, within 1%, within 0.1%, and within 0.01% of the stated amount. In addition, it should be understood that any directions or reference frames in the foregoing description are merely relative directions or movements. For example, any reference to "up" and "down" or "above" or "below" merely describes the relative position or movement of the associated elements.

[0082] Without departing from the spirit or characteristics of the present disclosure, the present disclosure may be embodied in other specific forms. The described embodiments should be considered as merely illustrative and not restrictive. Therefore, the scope of the present disclosure is indicated by the appended claims rather than by the foregoing description. Changes within the meaning and scope of the equivalents of the claims are included within the scope of the claims.

Claims

1. A control unit, comprising: Spindle; a tubular body rotatable relative to the spindle, the tubular body comprising a plurality of fins; a torque transmission unit having a first member attached to the spindle and a second member attached to the tubular body, the first member having a first bearing surface and the second member having a second bearing surface, the first bearing surface and the second bearing surface contacting each other with a certain friction force; as well as A torque generator is configured to apply torque to the main shaft.

2. The control unit of claim 1, further comprising a second torque transfer unit adjacent to the torque transfer unit, the second torque transfer unit having a first support member attached to the main shaft and a second support member attached to the tubular body. 3 . The control unit of claim 1 , wherein the friction force is dependent on the friction force between the first member and the second member. The control unit according to claim 1 , wherein the friction force is independent of the rotational speed above a minimum rotational speed.

5. The control unit of claim 1, further comprising a biasing element that maintains the position of the first member against the second member with a certain force.

6. The control unit of claim 5, the biasing element being selected from the group consisting of a resilient member, a compliant member, a conical washer, a frustoconical washer, a Belleville spring, a coil spring, a leaf spring, a hydraulic piston, and a pneumatic piston.

7. The control unit of claim 1, the tubular body being rotationally connected to a drill head.

8. A method for biasing a control unit according to any one of claims 1 to 7, comprising: rotating a tubular body at a certain rotational speed, the tubular body being connected to a first member of a torque transmission unit, a second member of the torque transmission unit being rigidly attached to a main shaft coaxial with the tubular body; applying a force against the second member using a biasing element; applying a first torque on the spindle by sliding the first member against the second member; as well as A second torque is applied to the spindle using a torque generator.

9. The method of claim 8, wherein applying the first torque is dependent upon the force against the second member.

10. The method of claim 8, wherein rotating the tubular body comprises rotating the tubular body at a minimum rotational speed relative to the spindle. 11 . The method of claim 10 , wherein when the rotational speed is greater than the minimum rotational speed, applying the first torque is independent of the rotational speed.

12. The method according to claim 8, further comprising: determining a net torque on the spindle sufficient to maintain absolute axial orientation, the net torque being the difference between the first torque and the second torque; as well as The net torque is controlled by varying the second torque using the torque generator.

13. The method of claim 8, further comprising varying the first torque by varying the force applied by the biasing element.

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