Small-diameter rotary steering drilling tool and drilling method

Abstract

The invention relates to the technical field of coal mine underground drilling, in particular to a small-diameter rotary steering drilling tool and a drilling method. The small-diameter rotary steering drilling tool comprises a shell assembly, a mandrel assembly, a rotary measuring assembly, a clutch assembly, a variable-diameter supporting assembly and a bearing assembly; the mandrel assembly is arranged in the shell assembly and is of a hollow structure, and the rotation measurement assembly is arranged between the rotation measurement shell and the first rotating shaft and comprises a rotation measurement device rotating along with the first rotating shaft and a rotation structure part; the clutch assembly is arranged between the clutch assembly shell and the second rotating shaft, and the clutch assembly can drive the second rotating shaft and the clutch assembly shell to rotate synchronously; the variable-diameter supporting assembly is arranged between the supporting assembly shell and the second rotating shaft and comprises a supporting wing, and the supporting wing moves in the radial direction of the second rotating shaft. According to the invention, the measuring device and the rotary guiding part are integrated, so that signal measurement and transmission under the rotating state of the drill column can be realized; and through axial combination of multiple groups of friction plates, reliable meshing with large torque can be realized.

Description

Technical Field

[0001] This invention relates to the field of underground drilling technology in coal mines, and in particular to small-diameter rotary steerable drill bits and drilling methods. Background Technology

[0002] In recent years, directional drilling technology has been widely adopted in coal mine operations such as gas extraction and water hazard detection. Traditional directional drilling technology uses a bottom-hole screw motor sliding directional drilling mode, which suffers from low output power and drill string pressure issues in long boreholes, severely restricting efficient deep-hole directional drilling. Rotary steerable drilling technology uses a drilling rig to drive the drill string for directional drilling, offering advantages such as high output power and effectively solving the problem of increased friction caused by drill string pressure during rotation, leading to rapid development in the oil drilling field. However, rotary steerable drill bits in the oil drilling field have complex structures and large diameters, making them unsuitable for the small-diameter drilling environment in coal mines. To address this, patent CN108343380A discloses a directional rotary directional drilling tool and method for near-horizontal drilling in coal mines. While technically feasible for rotary steerable drilling, it suffers from the following problems: the measuring instrument separates from the steerable tool during drilling, making it impossible to monitor the tool face angle in real time; and the performance of the irregularly shaped piston and keyway clutch is unreliable, resulting in low engagement torque. Summary of the Invention

[0003] This invention aims to solve the above problems and provides a small-diameter rotary steerable drill bit and drilling method, the technical solution of which is as follows: A small-diameter rotary steerable drill bit includes a housing assembly, a mandrel assembly, a rotary measuring assembly, a clutch assembly, a variable-diameter support assembly, and a bearing assembly. The housing assembly comprises a rotary measuring housing, a fixed-wing joint, a clutch assembly housing, a first bearing assembly housing, a support assembly housing, a universal joint housing, and a second bearing assembly housing, all connected axially and operating synchronously. The universal joint housing is a bent pipe. The mandrel assembly is housed within the housing assembly and is a hollow structure, comprising a first joint, a first rotating shaft, a coupling, a second rotating shaft, a universal joint, a front drive shaft, and a lower joint, all connected axially and operating synchronously. The rotary measuring assembly is located between the rotary measuring housing and the first rotating shaft. The rotary measuring assembly includes a measuring device and a structural part for mounting and connecting the measuring device. The device includes a fixed measuring device and a rotating measuring device, the rotating measuring device being electrically connected to the fixed measuring device. The structural part includes a rotating structural part and a fixed structural part, the rotating structural part and the fixed structural part being slidably connected. The rotating structural part and the rotating measuring device rotate synchronously with the first rotating shaft. The fixed measuring device is fixedly connected to the rotating measuring housing through the fixed structural part. The variable diameter support assembly is disposed between the support assembly housing and the second rotating shaft. The variable diameter support assembly includes a support wing, the support wing being radially movable along the second rotating shaft, and the outer surface of the support wing protruding outside the support assembly housing. The bearing assembly includes a first bearing and a second bearing, the first bearing and the second bearing being respectively disposed within the first bearing assembly housing and the second bearing assembly housing. A universal joint is disposed within the universal joint housing.

[0004] Based on the above scheme, the rotating structure includes a cable connector and an inner insulating sleeve, the fixed structure includes a first plug, an outer insulating sleeve, and an instrument frame, and the fixed structure is fixedly connected to the rotating measuring housing. The rotating measuring device includes a first wire, and the fixed measuring device includes a second conductive grease, a second wire, and a measuring circuit board connected in sequence. The cable connector is fixedly installed inside the cavity of the first connector. The first plug, the outer insulating sleeve, and the instrument frame are sequentially sleeved on the outside of the first rotating shaft along the axial direction. The inner insulating sleeve is disposed between the outer insulating sleeve and the first rotating shaft and is fixedly connected to the first rotating shaft. The space between the inner insulating sleeve and the outer insulating sleeve is filled with an annular second conductive grease. A wiring hole is provided radially at the connection between the first rotating shaft and the inner insulating sleeve. One end of the first wire is fixedly installed on the cable connector, and the other end passes through the internal cavity of the first rotating shaft and the inner insulating sleeve in sequence before being electrically connected to the second conductive grease. The second wire passes through the outer insulating sleeve. The measuring circuit board is fixedly installed on the instrument frame.

[0005] Based on the above scheme, a spline groove is provided on the outer surface of the first rotating shaft, and an internal spline that mates with the spline groove of the first rotating shaft is provided on the inner surface of the inner insulating sleeve, and the internal spline is engaged in the spline groove; a fixing key is provided at the end of the outer insulating sleeve facing the instrument frame, the fixing key extends outward along the axial direction, there are multiple fixing keys, and they are evenly spaced along the circumference, the end of the instrument frame facing the outer insulating sleeve is recessed inward along the axial direction to form a groove, and the fixing key is engaged in the groove.

[0006] Preferably, the second wire is connected to the positive terminal of the measuring circuit board, and the negative terminal of the measuring circuit board is connected to the rotating measuring housing; the first plug is radially mounted with a first oil plug, and the end of the first oil plug near the first rotating shaft is filled with a first conductive grease between it and the first rotating shaft, and the first conductive grease is annularly coated on the outer surface of the first rotating shaft.

[0007] Preferably, a first plug is installed at the end of the cable connector near the first rotating shaft, a second plug is installed at the cable routing hole of the first rotating shaft, a third plug is installed at the end of the outer insulating sleeve near the instrument frame along the axial direction, and a fourth plug is installed at the end of the instrument frame near the outer insulating sleeve along the axial direction; the first wire is a single-core wire with an insulating sleeve; a plug sealing ring is filled between the inner surface of the first plug and the first rotating shaft, a shell sealing ring is filled between the outer surface of the first plug and the rotating measuring shell, an inner insulating sleeve sealing ring is filled between the inner insulating sleeve and the outer insulating sleeve, an outer insulating sleeve sealing ring is filled at the radial contact position between the outer insulating sleeve and the instrument frame, and a frame sealing ring is filled between the instrument frame and the rotating measuring shell.

[0008] Preferably, the clutch assembly includes a static friction plate, a dynamic friction plate, and a sliding sleeve. The sliding sleeve is sleeved on the outside of the second rotating shaft and slides axially. The static friction plate and the dynamic friction plate are arranged in pairs and are located between the end of the fixed wing joint and the end of the sliding sleeve. The clutch assembly housing has a housing spline groove arranged axially. The outer side of the static friction plate protrudes outward to form an external spline, which is engaged in the housing spline groove. The inner side of the dynamic friction plate protrudes outward to form an internal spline. The outer surface of the second rotating shaft has a rotating shaft spline groove arranged radially, and the internal spline is engaged in the rotating shaft spline groove. When the sliding sleeve slides axially to the connection position, the adjacent static friction plate and the dynamic friction plate abut and rotate synchronously. When the sliding sleeve slides axially to the release position, there is a gap between the adjacent static friction plate and the dynamic friction plate.

[0009] Based on the above scheme, the second rotating shaft is a stepped shaft, and the stepped surface is located at the connection between the sliding sleeve and the second rotating shaft. A sliding sleeve cavity is formed between the inner end of the second sliding sleeve and the stepped surface of the second rotating shaft. A first flow hole is provided radially on the second rotating shaft. The first flow hole communicates with the internal cavity of the second rotating shaft and the sliding sleeve cavity. The clutch assembly also includes a sliding sleeve spring, which is sleeved on the outside of the second rotating shaft and abuts against the outer surface of the sliding sleeve end and the end of the first bearing assembly housing.

[0010] Preferably, the variable diameter support assembly further includes a capsule body and a rubber sleeve. The capsule body and the rubber sleeve are respectively sleeved on the outside of the second rotating shaft, and the capsule body is connected to both ends of the rubber sleeve in the axial direction. The support wing is disposed on the outside of the rubber sleeve. The outer shell of the support assembly is provided with an opening. The support wing is disposed through the opening, and the outer peripheral surface of the support wing and the outer shell of the support assembly are filled with a support wing sealing ring. A gap is provided between the second rotating shaft and the rubber sleeve. The second rotating shaft is provided with a second flow hole in the radial direction. The second flow hole communicates with the internal cavity of the second rotating shaft and the gap on the inner side of the rubber sleeve.

[0011] Preferably, the universal joint adopts a mushroom-shaped structure.

[0012] A drilling method using the aforementioned rotary steerable drill string includes the following steps: S1. Use conventional drill rods and drill bits to open holes, and the hole depth shall not be less than 3m; S2. Lower the rotary directional drill bit, and connect the free end of the first joint to the through-cable drill rod; S3. Pump water into the hollow structure of the mandrel assembly and observe the clutch performance of the clutch assembly and the support condition of the support wings of the variable diameter support assembly. S4. Adjust the universal joint housing to be directly above in the vertical plane, and adjust the tool face angle to 0°; S5. Stop pumping water, so that the clutch assembly is in the engagement position, and the variable diameter support assembly drives the support wing to retract inward without contacting the hole wall, so that the housing assembly and the spindle assembly rotate synchronously. S6. Adjust the working face according to the borehole design trajectory; S7. Start pumping water, so that the clutch assembly is in the disengaged position. The variable diameter support assembly drives the support wing to move outward until it abuts against the bore wall. At this time, the housing assembly does not rotate with the spindle assembly. S8. Under the action of the axis reversal of the universal joint housing, the drill bit cuts and drills in the direction of the adjusted tool face; S9. After reaching the designed position, lift the drill string and disassemble the rotary steerable drill string.

[0013] The beneficial effects of this invention are as follows: By integrating the measuring device with the rotary guide section, signal measurement and transmission can be achieved while the drill string is rotating, thereby enabling real-time monitoring of the tool face angle during rotary steer drilling. By axially combining multiple sets of friction plates, reliable meshing with high torque can be achieved, overcoming the problem of unreliable clutch performance of irregular pistons and keyways in the existing technology, and improving the ability to handle accidents inside the hole. The variable diameter support assembly enables adaptive movement of the support wings, which can adaptively adjust the support position and support force according to the borehole diameter, ensuring stability and reliability. Support wing sealing rings are installed on both sides of the support wings to prevent drill cuttings from entering the drill bit and causing mechanical failure. By connecting the hollow chamber of the spindle assembly with the clutch assembly and the variable diameter support assembly, the coordinated action of synchronous rotation of the outer shell and the spindle during water pumping and stable support of the outer shell when water is stopped is achieved, making operation convenient and reliable. Attached Figure Description

[0014] Figure 1 : Schematic diagram of the structure of the present invention; Figure 2 : A cross-sectional view of the rotating measurement assembly structure of this invention; Figure 3 : Cross-sectional view of the outer insulating sleeve structure of the present invention; Figure 4 : Cross-sectional view of the inner insulating sleeve structure of the present invention; Figure 5 This invention Figure 4 Sectional view of section AA; Figure 6 : A cross-sectional view of the clutch assembly structure of the present invention; Figure 7 : Schematic diagram of the clutch assembly housing structure of the present invention; Figure 8 : Schematic diagram of the static friction plate and dynamic friction plate of the present invention; Figure 9 : A cross-sectional view of the variable diameter support assembly structure of the present invention; Figure 10 This invention Figure 9 Sectional view of section BB; Figure 11 : Schematic diagram of the supporting wing structure of the present invention; Figure 12 : Schematic diagram of the limiting sleeve structure of the present invention; Figure 13 Cross-sectional view of the universal joint structure of this invention: Figure 14 Diagram showing the angle relationship of the tool in this invention. Detailed Implementation

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments: In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0016] In the description of this invention, it should be understood that the terms "center," "length," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," and "inner," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0017] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0018] like Figures 1 to 13 As shown, a small-diameter rotary steerable drill bit includes a housing assembly, a mandrel assembly, a rotary measuring assembly 3, a clutch assembly 4, a variable diameter support assembly, and a bearing assembly.

[0019] The housing assembly includes a rotary measuring housing 11, a fixed wing connector 12, a clutch assembly housing 13, a first bearing assembly housing 14, a support assembly housing 16, a universal joint housing 17, and a second bearing assembly housing 18, which are connected axially and operate synchronously. The universal joint housing 17 is a bent pipe. The fixed wing connector 12 has a fixed wing protruding outward from its outer surface, and the fixed wing is used for support at the inner wall of the borehole.

[0020] The bearing assembly includes a first bearing 141 and a second bearing 181, which are respectively disposed within a first bearing assembly housing 14 and a second bearing assembly housing 18. The number of first bearings 141 and second bearings 181 can be multiple, and they can be TC bearings, thrust tandem bearings, etc. A universal joint 25 is disposed within a universal joint housing 17. A first transition joint 151 connects the first bearing assembly housing 14 and the support assembly housing 16, and a second transition joint 152 connects the support assembly housing 16 and the universal joint housing 17. A plug 19 is connected to the end of the second bearing assembly housing 18 away from the second transition joint 152.

[0021] The mandrel assembly is housed within the outer casing assembly and has a hollow structure. It includes a first connector 21, a first rotating shaft 22, a coupling 23, a second rotating shaft 24, a universal joint 25, a front drive shaft 26, and a lower connector 27, all connected and operating synchronously on their axes. The end of the first connector 21 is connected to a cable-carrying drill rod.

[0022] The rotating measurement assembly 3 is disposed between the rotating measurement housing 11 and the first rotating shaft 22. The rotating measurement assembly 3 includes a measuring device and a structural part for mounting and connecting the measuring device. The measuring device includes a fixed measuring device and a rotating measuring device. The rotating measuring device is electrically connected to the fixed measuring device. The structural part includes a rotating structural part and a fixed structural part. The rotating structural part and the fixed structural part are slidably connected. The rotating structural part and the rotating measuring device rotate synchronously with the first rotating shaft 22. The fixed measuring device is fixedly connected to the rotating measurement housing 11 through the fixed structural part.

[0023] Specifically, such as Figure 2As shown, the rotating structure includes a cable connector 31 and an inner insulating sleeve 36; the fixed structure includes a first plug 34, an outer insulating sleeve 35, and an instrument frame 38, and the fixed structure is fixedly connected to the rotating measuring housing 11; the rotating measuring device includes a first wire 33; the fixed measuring device includes a second conductive lubricant 372, a second wire 374, and a measuring circuit board 382 connected in sequence; the cable connector 31 is fixedly installed inside the cavity of the first connector 21; the first plug 24, the outer insulating sleeve 35, and the instrument frame 38 are sequentially sleeved along the axial direction onto the first rotating shaft 22. On the outside, an inner insulating sleeve 36 is disposed between the outer insulating sleeve 35 and the first rotating shaft 22, and is fixedly connected to the first rotating shaft 22. An annular second conductive grease 372 is filled between the inner insulating sleeve 36 and the outer insulating sleeve 35. A wiring hole is radially provided at the connection point between the first rotating shaft 22 and the inner insulating sleeve 36. One end of the first wire 33 is fixedly installed on the cable connector 31, and the other end passes sequentially through the internal cavity of the first rotating shaft 22 and the inner insulating sleeve 36 before being electrically connected to the second conductive grease 372. The second wire 374 passes through the outer insulating sleeve 35. The measuring circuit board 382 is fixedly installed on the instrument frame 38. Through this structure, the first wire 33 can rotate with the first connector 21 and the cable connector 31, and the electrical signal in the first wire 33 continues to be transmitted backward through the annular second conductive grease 372 to the second wire 374 and the measuring circuit board 382, ​​thereby enabling real-time transmission of electrical signals during the rotation of the spindle assembly.

[0024] The second wire 374 is connected to the positive terminal of the measuring circuit board 382, ​​and the negative terminal of the measuring circuit board 382 is connected to the rotating measuring housing 11. The first plug 34 is radially fitted with a first oil plug 341, and the end of the first oil plug 341 near the first rotating shaft 22 is filled with a first conductive grease 342. The first conductive grease 342 is annularly coated on the outer surface of the first rotating shaft 22. Thus, the circuit setup of the measuring circuit board 382 is achieved through the above structure: the positive terminal of the measuring circuit board 382 is connected to the cable connector 31 in sequence through the second wire 374, the second conductive grease 372, and the first wire 33; the negative terminal of the measuring circuit board 382 is connected to the first connector 21 in sequence through the rotating measuring housing 11, the first plug 34, the first conductive grease 342, and the outer wall of the first rotating shaft 22, and is further connected to the ground through the cable drill rod connected to the first connector 21, thereby realizing measurement and transmission of measurement signals. The above scheme enables the rotatable connection between the positive terminal of the measuring circuit board 382 and the drill rod with the connecting cable while the mandrel assembly is rotating. The measurement principle and method are the same as those of conventional measurement principles and methods, and will not be elaborated here.

[0025] A first plug 32 is installed at the end of the cable connector 31 near the first rotating shaft 22. A second plug 371 is installed at the cable routing hole of the first rotating shaft 22. A third plug 373 is installed at the end of the outer insulating sleeve 35 along the axial direction near the instrument frame 38. A fourth plug 381 is installed at the end of the instrument frame 38 along the axial direction near the outer insulating sleeve 35. The first wire 33 is a single-core wire with an insulating sleeve. The above structure enables reliable transmission of electrical signals and prevents damage to the measuring device and the electrical signal transmission path caused by drilling cuttings, liquids, etc. Preferably, a plug sealing ring 343 is filled between the inner surface of the first plug 34 and the first rotating shaft 22, a shell sealing ring is filled between the outer surface of the first plug 34 and the rotating measuring shell 11, an inner insulating sleeve sealing ring 365 is filled between the inner insulating sleeve 36 and the outer insulating sleeve 35, an outer insulating sleeve sealing ring 358 is filled at the radial contact position between the outer insulating sleeve 35 and the instrument frame 38, and a frame sealing ring 383 is filled between the instrument frame 38 and the rotating measuring shell 11.

[0026] Specifically, such as Figure 3 As shown, the outer insulating sleeve 35 includes an outer insulating sleeve body 351. A first grease-receiving groove 352 is radially recessed on the inner side of the outer insulating sleeve body 351 at a position corresponding to the inner insulating sleeve 36. The first grease-receiving groove 352 is filled with a first conductive grease 342. A wire-passing hole 353 and a grease injection hole 355 are provided axially on the outer insulating sleeve body 351. A first plug hole 354 is provided at the end of the wire-passing hole 353. A second wire 374 passes through the wire-passing hole 353. A third plug 373 is provided in the first plug hole 354. The grease injection hole 355 is filled with conductive grease. A first sealing ring groove 356 is provided on the outer surface of the outer insulating sleeve body 351, in which an outer insulating sleeve sealing ring 358 is engaged. Figure 4 and Figure 5 As shown, the inner insulating sleeve 36 includes an inner insulating sleeve body 361. The inner insulating sleeve body 361 is coaxially provided with a second plug hole 362 at the corresponding position of the wiring hole. The second plug hole 362 contains a second plug 371. The first wire 33 passes through the second plug 371. A second grease receiving groove 363 is formed on the outside of the second plug hole 362. It and the first grease receiving groove 352 form an annular structure and are filled with second conductive grease 372. A second sealing ring groove 364 is provided on the outer surface of the inner insulating sleeve body 361. The inner insulating sleeve sealing ring 365 is contained in the groove. There are two inner insulating sleeve sealing rings 365, which are arranged axially on opposite sides of the second plug hole 362.

[0027] To achieve synchronous rotation between the rotary measuring assembly 3 and the first rotating shaft 22, a spline groove is provided on the outer surface of the first rotating shaft 22, and an internal spline is provided on the inner surface of the inner insulating sleeve 36 to mate with the spline groove of the first rotating shaft 22, and the internal spline is engaged in the spline groove; a fixing key 357 is provided on the end of the outer insulating sleeve 35 facing the instrument frame 3, the fixing key 357 extends outward along the axial direction, there are multiple fixing keys 357, and they are evenly spaced along the circumference, the end of the instrument frame 3 facing the outer insulating sleeve 35 is recessed inward along the axial direction to form a groove, and the fixing key 357 is engaged in the groove, thereby transmitting the rotation of the first rotating shaft 22 sequentially through the inner insulating sleeve 36 and the outer insulating sleeve 35 to the instrument frame 38, and further driving the measuring circuit board 382 to rotate, thereby realizing the synchronous rotation of the measuring device and signal transmission.

[0028] The clutch assembly 4 is disposed between the clutch assembly housing 13 and the second rotating shaft 22. When the clutch assembly 4 is in the engaged position, it drives the second rotating shaft 22 to rotate synchronously with the clutch assembly housing 13. When the clutch assembly 4 is in the disengaged position, the second rotating shaft 22 does not rotate synchronously with the clutch assembly housing 13. Specifically, as shown... Figures 6 to 8 As shown, the clutch assembly 4 includes a stationary friction plate 41, a moving friction plate 42, and a sliding sleeve 43. The sliding sleeve 43 is sleeved on the outside of the second rotating shaft 24 and slides axially. The stationary friction plate 41 and the moving friction plate 42 are arranged in pairs, with multiple pairs of friction plates adjacent to each other and in contact, and are arranged between the end of the fixed wing joint 12 and the end of the sliding sleeve 43. The clutch assembly housing 13 has a housing spline groove 131 arranged axially inside. The outer side of the stationary friction plate 41 protrudes outward to form an outer spline 411, which is engaged in the housing spline groove 131. The inner side of the moving friction plate 42 protrudes outward to form an inner spline 421. The outer surface of the second rotating shaft 24 has a rotating shaft spline groove arranged radially, and the inner spline 421 is engaged in the rotating shaft spline groove, thereby realizing that the stationary friction plate 41 rotates synchronously with the clutch assembly housing 13, and the moving friction plate 42 rotates synchronously with the second rotating shaft 24. When the sliding sleeve 43 slides axially to the connection position, the adjacent static friction plates 41 and dynamic friction plates 42 abut and rotate synchronously. At this time, the rotation of the second rotating shaft 24 is transmitted to the static friction plates 41 through the dynamic friction plates 42, and the static friction plates 41 rotate through friction, thereby driving the clutch assembly housing 13 to rotate synchronously. Furthermore, it achieves synchronous movement between the housing assembly and the spindle assembly. When the sliding sleeve 43 slides axially to the disengagement position, there is a gap between the adjacent static friction plates 41 and dynamic friction plates 42. At this time, there is not enough friction between the static friction plates 41 and dynamic friction plates 42, and the dynamic friction plates 42 cannot drive the static friction plates 41 to rotate. Therefore, the clutch assembly housing 13 and the second rotating shaft 24 disengage. An appropriate amount of lubricating oil is injected into the friction plates to lubricate the static friction plates 41, dynamic friction plates 42, and other components.

[0029] As can be seen from the above analysis, this scheme achieves power transmission through the friction between adjacent friction plates. Therefore, the more friction plates there are, the greater the torque that can be transmitted.

[0030] Preferably, such as Figure 6 As shown, the second rotating shaft 24 is a stepped shaft, and the stepped surface is located at the connection between the sliding sleeve 43 and the second rotating shaft 24. A sliding sleeve cavity 431 is formed between the inner end of the second sliding sleeve 43 and the stepped surface of the second rotating shaft 24. A first flow hole 242 is provided radially on the second rotating shaft 24. The first flow hole 242 communicates with the internal cavity of the second rotating shaft 24 and the sliding sleeve cavity 431. The clutch assembly 4 also includes a sliding sleeve spring 44, which is sleeved on the second rotating shaft 24 and abuts against the outer surface of the end of the sliding sleeve 43 and the end of the first bearing assembly housing 14. When the internal cavity of the second rotating shaft 24 is filled with water under a certain pressure, the water flows through the first flow hole 242 into the sliding sleeve cavity 431. When the pressure of the water in the sliding sleeve cavity 431 on the sliding sleeve 43 is greater than the squeezing force of the sliding sleeve spring 44 on the sliding sleeve 43, the sliding sleeve 43 pushes the sliding sleeve spring 44 to compress, causing the sliding sleeve 43 to move away from the fixed wing joint 12 until the sliding sleeve 43 moves to the loosened position. When the water pressure decreases, the sliding sleeve 43 moves in the opposite direction under the action of the sliding sleeve spring 44 until it returns to the connected position. A spring limiting sleeve 45 is provided outside the sliding sleeve spring 44 to prevent the sliding sleeve spring 44 from deforming or shifting.

[0031] The variable diameter support assembly is disposed between the support assembly housing 16 and the second rotating shaft 24. The variable diameter support assembly includes a support wing 54, which moves radially along the second rotating shaft 24, and the outer surface of the support wing 54 protrudes beyond the outer side of the support assembly housing 16. Specifically, as... Figures 9 to 12The variable diameter support assembly further includes a capsule body 51 and a rubber sleeve 52. The capsule body 51 and the rubber sleeve 52 are respectively sleeved on the outside of the second rotating shaft 24, and the capsule body 51 is connected to both axial ends of the rubber sleeve 52. A support wing 54 is disposed on the outside of the rubber sleeve 52. An opening is provided on the outer shell 16 of the support assembly, and the support wing 54 passes through the opening. A gap is provided between the second rotating shaft 24 and the rubber sleeve 52. A second flow hole 243 is provided radially on the second rotating shaft 24. The second flow hole 243 communicates with the internal cavity of the second rotating shaft 24 and the gap inside the rubber sleeve 52. When the internal cavity of the second rotating shaft 24 is filled with water at a certain pressure, the water flows through the second flow hole 243 into the gap inside the rubber sleeve 52. The water flow in the gap will push the rubber sleeve 52 outward, thereby pushing the support wing 54 to move radially outward until it abuts against the borehole wall, thus achieving the support function. When the pumping stops, the rubber sleeve 52 and the support wing 54 retract radially inward to reset. Preferably, a support wing sealing ring 55 is filled between the outer peripheral surface of the support wing 54 and the outer shell 16 of the support assembly. The support wing sealing ring 55 can be a special-shaped sealing ring. By setting the support wing sealing ring 55, the gap between the support wing 54 and the outer shell of the support assembly 16 is filled and blocked, preventing drill cuttings from entering the drill bit from the gap.

[0032] A steel strip 521 is embedded axially in the rubber sleeve 52 to assist the rubber sleeve 52 in returning to its original position. A limiting sleeve 53 is also fitted on the outside of the rubber sleeve 52 to prevent damage caused by excessive deformation of the rubber sleeve 52. The limiting sleeve 53 has a limiting sleeve window 531 along the axial direction, and a support wing 54 is disposed at the limiting sleeve window 531. The support wing 54 includes a support body 541, the outer surface of which is a support surface 542. Hard alloy pillars 543 are arranged radially along the rubber sleeve 52 inside the support wing 54 to strengthen the structural strength of the support wing 54 and prevent structural damage. The limiting wings 544 are fixedly connected to both sides of the support body 541 to limit the radial movement of the support wing 54.

[0033] Furthermore, a throttling nozzle 244 is installed in the inner cavity of the second rotating shaft 24 near the universal joint 25. The inner surface of the throttling nozzle 244 is formed by connecting a frustum and a cylindrical surface along the axial direction, and the inner diameter of the throttling nozzle 244 gradually increases in the direction away from the universal joint 25. This causes the water pressure in the inner cavity of the second rotating shaft 24 to increase through the throttling effect, thereby realizing the radial expansion of the rubber sleeve 52.

[0034] The variable diameter support assembly is connected to the first transition joint 151. A joint oil seal 1511 is provided radially on the first transition joint 151, and a joint sealing ring 1512 is filled between the first transition joint 151 and the second rotating shaft 24.

[0035] like Figure 13As shown, the universal joint 25 adopts a mushroom-shaped structure with gaps between the mushroom segments. Water flow channels exist radially at these gaps, thus achieving a certain degree of drainage and allowing the water flow in the drained portion to lubricate the second bearing 181. The universal joint 25 can also be any other structure with radially existing flow channels.

[0036] A drilling method using the aforementioned rotary steerable drill string includes the following steps: S1. Use conventional drill rods and drill bits to open holes, and the hole depth shall not be less than 3m; S2. Lower the rotary directional drill bit, and connect the free end of the first joint 21 to the cable-connected drill rod; S3. Pump water into the hollow structure of the mandrel assembly and observe the clutch performance of the clutch assembly and the support condition of the support wing 54 of the variable diameter support assembly. S4. Adjust the universal joint housing 17 to be directly above in the vertical plane, and adjust the tool face angle to 0°; S5. Stop pumping water, so that the clutch assembly is in the engagement position, the variable diameter support assembly drives the support wing 54 to retract inward, and does not abut against the hole wall or make non-supporting contact with the hole wall, so that the housing assembly and the spindle assembly rotate synchronously. S6. Adjust the working face according to the borehole design trajectory; during the adjustment process, if... Figure 14 As shown, the radial mounting position of the measuring circuit board 382 does not affect the drill tool face angle, i.e. ,in To measure the tool face angle when the circuit board 382 is centered, To measure the tool face angle when the circuit board 382 is biased; S7. Start pumping water, so that the clutch assembly is in the disengaged position. The variable diameter support assembly drives the support wing 54 to move outward until it abuts against the bore wall. At this time, the housing assembly does not rotate with the spindle assembly. S8. Under the action of the axis reversal of the universal joint housing 17, the drill bit cuts and drills in the direction of the adjusted tool face; S9. After reaching the designed position, lift the drill string and disassemble the rotary steerable drill string.

[0037] The present invention has been described above by way of example, but the present invention is not limited to the specific embodiments described above. Any modifications or variations made based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A small-diameter rotary steerable drill bit, characterized in that, The assembly includes a housing assembly, a spindle assembly, a rotary measuring assembly (3), a clutch assembly (4), a variable diameter support assembly, and a bearing assembly. The housing assembly includes a rotary measuring housing (11), a fixed wing joint (12), a clutch assembly housing (13), a first bearing assembly housing (14), a support assembly housing (16), a universal joint housing (17), and a second bearing assembly housing (18), which are connected axially and move synchronously. The universal joint housing (17) is a bent tube. The spindle assembly is located inside the housing assembly and has a hollow structure. The spindle assembly includes axes connected axially and move synchronously. The actuating components include a first connector (21), a first rotating shaft (22), a coupling (23), a second rotating shaft (24), a universal joint (25), a front drive shaft (26), and a lower connector (27). The rotary measuring assembly (3) is disposed between the rotary measuring housing (11) and the first rotating shaft (22). The rotary measuring assembly (3) includes a measuring device and a structural part for mounting and connecting the measuring device. The measuring device includes a fixed measuring device and a rotary measuring device, which are electrically connected to the fixed measuring device. The structural part includes a rotary structural part and a fixed structural part. The rotating structure and the fixed structure are slidably connected. The rotating structure and the rotating measuring device rotate synchronously with the first rotating shaft (22). The fixed measuring device is fixedly connected to the rotating measuring housing (11) through the fixed structure. The clutch assembly (4) is disposed between the clutch assembly housing (13) and the second rotating shaft (22). When the clutch assembly (4) is in the connected position, it drives the second rotating shaft (22) to rotate synchronously with the clutch assembly housing (13). When the clutch assembly (4) is in the disengaged position, the second rotating shaft (22) does not rotate synchronously with the clutch assembly housing (13). The variable diameter support assembly The variable diameter support assembly is located between the support assembly housing (16) and the second rotating shaft (24). The support wing (54) is radially movable along the second rotating shaft (24), and the outer surface of the support wing (54) protrudes out of the support assembly housing (16). The bearing assembly includes a first bearing (141) and a second bearing (181). The first bearing (141) and the second bearing (181) are respectively located in the first bearing assembly housing (14) and the second bearing assembly housing (18). A universal shaft (25) is located in the universal shaft housing (17).

2. The small-diameter rotary steerable drill bit according to claim 1, characterized in that, The rotating structure includes a cable connector (31) and an inner insulating sleeve (36). The fixed structure includes a first plug (34), an outer insulating sleeve (35), and an instrument frame (38). The fixed structure is fixedly connected to the rotating measuring housing (11). The rotating measuring device includes a first wire (33). The fixed measuring device includes a second conductive grease (372), a second wire (374), and a measuring circuit board (382) connected in sequence. The cable connector (31) is fixedly installed inside the cavity of the first connector (21). The first plug (24), the outer insulating sleeve (35), and the instrument frame (38) are sequentially sleeved on the outside of the first rotating shaft (22) along the axial direction. An insulating sleeve (36) is disposed between the outer insulating sleeve (35) and the first rotating shaft (22) and is fixedly connected to the first rotating shaft (22). The inner insulating sleeve (36) and the outer insulating sleeve (35) are filled with annular second conductive grease (372). A wiring hole is provided radially at the connection between the first rotating shaft (22) and the inner insulating sleeve (36). One end of the first wire (33) is fixedly installed on the cable connector (31), and the other end passes through the internal cavity of the first rotating shaft (22) and the inner insulating sleeve (36) in sequence and is electrically connected to the second conductive grease (372). The second wire (374) is disposed through the outer insulating sleeve (35). The measuring circuit board (382) is fixedly installed on the instrument frame (38).

3. A small-diameter rotary directional drill bit according to claim 2, characterized in that, The outer surface of the first rotating shaft (22) is provided with a spline groove, and the inner surface of the inner insulating sleeve (36) is provided with an inner spline that mates with the spline groove of the first rotating shaft (22), and the inner spline is engaged in the spline groove; a fixing key (357) is provided at the end of the outer insulating sleeve (35) facing the instrument frame (3), the fixing key (357) extends outward along the axial direction, there are multiple fixing keys (357), and they are evenly spaced along the circumference, the end of the instrument frame (3) facing the outer insulating sleeve (35) is recessed inward along the axial direction to form a groove, and the fixing key (357) is engaged in the groove.

4. A small-diameter rotary steerable drill bit according to claim 2, characterized in that, The second wire (374) is connected to the positive terminal of the measuring circuit board (382), and the negative terminal of the measuring circuit board (382) is connected to the rotating measuring housing (11); the first plug (34) is radially mounted with a first oil plug (341), and the end of the first oil plug (341) near the first rotating shaft (22) is filled with a first conductive grease (342), and the first conductive grease (342) is annularly coated on the outer surface of the first rotating shaft (22).

5. A small-diameter rotary steerable drill bit according to claim 2, characterized in that, A first plug (32) is installed at the end of the cable connector (31) near the first rotating shaft (22), a second plug (371) is installed at the cable routing hole of the first rotating shaft (22), a third plug (373) is installed at the end of the outer insulating sleeve (35) near the instrument frame (38) along the axial direction, and a fourth plug (381) is installed at the end of the instrument frame (38) near the outer insulating sleeve (35) along the axial direction; the first wire (33) is a single-core wire with an insulating sleeve; the first plug (34) The inner surface of the first plug (34) is filled with a plug sealing ring (343) between the inner surface and the first rotating shaft (22), the outer surface of the first plug (34) is filled with a shell sealing ring between the outer surface and the rotating measuring shell (11), the inner insulating sleeve sealing ring (365) is filled between the inner insulating sleeve (36) and the outer insulating sleeve (35), the outer insulating sleeve sealing ring (358) is filled at the radial contact position between the outer insulating sleeve (35) and the instrument frame (38), and the frame sealing ring (383) is filled between the instrument frame (38) and the rotating measuring shell (11).

6. A small-diameter rotary steerable drill bit according to claim 1, characterized in that, The clutch assembly (4) includes a stationary friction plate (41), a moving friction plate (42), and a sliding sleeve (43). The sliding sleeve (43) is sleeved on the outside of the second rotating shaft (24) and slides axially. The stationary friction plate (41) and the moving friction plate (42) are arranged in pairs and are located between the end of the fixed wing joint (12) and the end of the sliding sleeve (43). The clutch assembly housing (13) is provided with a housing spline groove (131) axially inside. The outer side of the stationary friction plate (41) protrudes outward to form an external spline (411). 11) The inner spline (42) of the moving friction plate (42) protrudes outward to form an inner spline (421) in the spline groove (131) of the outer shell. The outer surface of the second rotating shaft (24) is provided with a rotating shaft spline groove along the radial axis. The inner spline (421) is engaged in the rotating shaft spline groove. When the sliding sleeve (43) slides to the connection position along the axial direction, the adjacent static friction plate (41) and the moving friction plate (42) abut and rotate synchronously. When the sliding sleeve (43) slides to the release position along the axial direction, there is a gap between the adjacent static friction plate (41) and the moving friction plate (42).

7. A small-diameter rotary steerable drill bit according to claim 6, characterized in that, The second rotating shaft (24) is a stepped shaft, and the stepped surface is located at the connection between the sliding sleeve (43) and the second rotating shaft (24). A sliding sleeve cavity (431) is formed between the inner end of the second sliding sleeve (43) and the stepped surface of the second rotating shaft (24). A first flow hole (242) is provided radially on the second rotating shaft (24). The first flow hole (242) is connected to the internal cavity of the second rotating shaft (24) and the sliding sleeve cavity (431). The clutch assembly (4) also includes a sliding sleeve spring (44). The sliding sleeve spring (44) is sleeved on the outside of the second rotating shaft (24) and abuts against the outer surface of the end of the sliding sleeve (43) and the end of the first bearing assembly housing (14).

8. A small-diameter rotary steerable drill bit according to claim 1, characterized in that, The variable diameter support assembly further includes a capsule body (51) and a rubber sleeve (52). The capsule body (51) and the rubber sleeve (52) are respectively sleeved on the outside of the second rotating shaft (24), and the capsule body (51) is connected to both ends of the rubber sleeve (52) in the axial direction. The support wing (54) is disposed on the outside of the rubber sleeve (52). An opening is provided on the support assembly housing (16). The support wing (54) is disposed through the opening, and a support wing sealing ring (55) is filled between the outer peripheral surface of the support wing (54) and the support assembly housing (16). A gap is provided between the second rotating shaft (24) and the rubber sleeve (52). A second flow hole (243) is provided in the radial direction of the second rotating shaft (24). The second flow hole (243) is connected to the internal cavity of the second rotating shaft (24) and the gap on the inner side of the rubber sleeve (52).

9. A small-diameter rotary steerable drill bit according to claim 1, characterized in that, The universal joint (25) adopts a mushroom-shaped structure.

10. A drilling method, characterized in that, The rotary steerable drill string as described in any one of claims 1-9 is characterized by comprising the following steps: S1. Use conventional drill rods and drill bits to open holes, and the hole depth shall not be less than 3m; S2. Lower the rotary directional drill bit, and connect the free end of the first joint (21) to the cable-connected drill rod; S3. Pump water into the hollow structure of the mandrel assembly and observe the clutch performance of the clutch assembly and the support condition of the support wing (54) of the variable diameter support assembly; S4. Adjust the universal joint housing (17) to be directly above in the vertical plane, and correct the tool face angle to 0°; S5. Stop pumping water, so that the clutch assembly is in the engagement position, and the variable diameter support assembly drives the support wing (54) to retract inward without contacting the hole wall, so that the housing assembly and the spindle assembly rotate synchronously. S6. Adjust the working face according to the borehole design trajectory; S7. Start pumping water, so that the clutch assembly is in the disengaged position, and the variable diameter support assembly drives the support wing (54) to move outward until it abuts against the hole wall. At this time, the housing assembly does not rotate with the spindle assembly. S8. Under the axial reversal action of the universal joint housing (17), the drill bit cuts and drills in the direction of the adjusted tool face; S9. After reaching the designed position, lift the drill string and disassemble the rotary steerable drill string.

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