Rotary Directional Drilling Tool, Drilling String and Drilling Control Method

Abstract

The present invention provides a rotary steerable drilling tool, a drilling string and a drilling control method. The rotary steerable drilling tool includes: a tool housing, an inner shaft, a rotor, an upper sealing piston, a lower sealing piston and a lower piston fixed shaft. The inner shaft, the rotor and the lower piston fixed shaft are all arranged in the tool housing and distributed in sequence, and a flow channel for conveying drilling fluid is provided. A stator matched with the rotor is arranged in the tool housing; the upper sealing piston and the lower sealing piston are both arranged in the tool housing and are respectively in sealing cooperation with the inner wall of the tool housing; an inner fluid channel is formed between the upper sealing piston and the lower sealing piston; the tool housing is provided with a fluid inlet and a fluid outlet which are respectively communicated with the inner fluid channel. The fluid inlet is located between the lower sealing piston and the rotor, and the fluid outlet is arranged between the upper sealing piston and the rotor, solving the technical problem that the operation difficulty of rotary steerable drilling is relatively large.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas drilling engineering, and particularly to a rotary steerable drilling tool, a drilling string and a drilling control method. Background Art

[0002] Directional drilling refers to a drilling technology in which drilling is carried out according to the pre-designed well inclination and azimuth to achieve the expected wellbore trajectory. The existing directional drilling technologies can be divided into: sliding directional drilling technology and rotary steerable drilling technology according to the different working modes of the steering tools. The sliding directional drilling technology and the rotary steerable drilling technology have different applicable ranges, so it is necessary to select different drilling methods corresponding to different working conditions during the drilling process. The rotary steerable drilling technology is expensive and is only suitable for use in key wells and high-benefit blocks. In areas where the reservoir is relatively stable, sliding direction is still the main directional drilling method. With the increase of the horizontal section, during the traditional sliding directional drilling process, the friction is large and the problem of sticking to the drill pipe is prominent. In view of the problems such as the high cost of the rotary steerable drilling technology and the limited horizontal section length of the traditional sliding directional drilling, it is necessary to develop a new type of rotary steerable drilling control tool and control method.

[0003] Chinese invention patent CN108868604B discloses a mechanical downhole torque separation and transmission tool, which is based on a conventional bent screw bottom hole assembly. The tool is installed on the drill string, and the rotary steerable drilling of the drill string is realized by separating the torque of the tool. This tool can replace the rotary steerable drilling system to realize the rotary steerable drilling of the drill string, and is used for directional drilling of complex structure wells such as directional wells, horizontal wells and extended reach wells. However, it can only realize rotary drilling.

[0004] Chinese invention patent CN111411904B discloses a downhole torque clutch type drilling drag reduction device based on RFID. The ground control signal is transmitted through a radio frequency ball, and an integral gear pair structure is adopted. The inner gear and the outer gear can be meshed and separated by moving up and down, which overcomes the defect of easy partial wear of the disengaged jaw clutch and overcomes the defect that the random effective meshing of the mechanical clutch structure cannot be guaranteed, and improves the reliability and stability of the clutch system. However, the use of RFID technology increases the difficulty of operation.

[0005] Chinese invention patent CN105525871B discloses a hydrodynamic torque converter, and proposes a hydrodynamic torque converter with simple structure, reliable performance, high control accuracy and convenient operation. When it is necessary to change the orientation of the tool face during the drilling process, the rotation speed of the drill string is increased. Since the drill string is connected to the central shaft, the rotation speed of the central shaft will also increase accordingly. The central shaft is connected to the torque generator. For the torque generator, as the input rotation speed increases, the clockwise torque it outputs will also increase. When the generated clockwise torque is greater than the counterclockwise torque transmitted from the bottom hole assembly, the bottom hole assembly will rotate in the clockwise direction. When the tool face rotates to the designed orientation, reducing the rotation speed of the drill string will also reduce the output torque of the torque generator. During rock drilling, as long as the rotation speed of the drill string is controlled so that the output torque of the torque generator is equal to the reverse torque of the bottom hole assembly, the directional drilling construction can be carried out. However, since it is necessary to identify the change of the tool face angle during the drilling process, it brings difficulties to the operation. Summary of the Invention

[0006] The object of the present invention is to provide a rotary steerable drilling tool, a drilling string and a drilling control method to solve the technical problem of relatively large operation difficulty in rotary steerable drilling.

[0007] The above object of the present invention can be achieved by the following technical solutions:

[0008] The present invention provides a rotary steerable drilling tool, including: a tool housing, an inner shaft, a rotor, an upper sealing piston, a lower sealing piston and a lower piston fixing shaft. The inner shaft, the rotor and the lower piston fixing shaft are all arranged in the tool housing and distributed in sequence. Moreover, the inner shaft, the rotor and the lower piston fixing shaft are connected to rotate together, and are provided with a flow channel for conveying drilling fluid. A stator cooperating with the rotor is arranged in the tool housing;

[0009] The upper sealing piston and the lower sealing piston are both arranged in the tool housing and are respectively in sealing cooperation with the inner wall of the tool housing;

[0010] The upper sealing piston is sleeved outside the inner shaft and is located above the rotor. The lower sealing piston is sleeved outside the lower piston fixing shaft and is located below the rotor. An inner fluid channel is formed between the upper sealing piston and the lower sealing piston;

[0011] The tool housing is provided with a fluid inlet and a fluid outlet respectively communicating with the inner fluid channel. The fluid inlet is located between the lower sealing piston and the rotor, and the fluid outlet is arranged between the upper sealing piston and the rotor.

[0012] In a preferred embodiment, the rotary steerable drilling tool includes a nozzle mechanism disposed within the inner fluid passage and above the rotor, and at least a portion of the fluid within the inner fluid passage flows through the nozzle mechanism.

[0013] In a preferred embodiment, the nozzle mechanism includes a nozzle seat sleeved outside the inner shaft and fixedly connected to the tool housing, and the nozzle seat is provided with a through hole penetrating up and down.

[0014] In a preferred embodiment, the nozzle seat is in sealing fit with the outer wall of the inner shaft, and the outer wall of the nozzle seat is in sealing fit with the inner wall of the tool housing.

[0015] In a preferred embodiment, the nozzle seat is provided with a plurality of the through holes, and at least one of the through holes is provided with a pressure nozzle.

[0016] In a preferred embodiment, the rotary steerable drilling tool includes a plurality of the nozzle mechanisms arranged at intervals in the longitudinal direction.

[0017] In a preferred embodiment, the inner shaft includes an upper piston fixed shaft, a central shaft, and a lower central shaft, which are sequentially distributed and connected. The upper sealing piston is sleeved outside the upper piston fixed shaft, and the nozzle seat is sleeved outside the central shaft.

[0018] In a preferred embodiment, the tool housing includes an upper fixed shaft housing, a differential pressure control assembly housing, and a lower piston housing that are sequentially distributed. The nozzle seat is fixedly connected to and in sealing fit with the differential pressure control assembly housing.

[0019] In a preferred embodiment, the tool housing includes a stator housing connected to the upper end of the lower piston housing. The stator is disposed within the stator housing, and the stator and the rotor are respectively provided with cooperating screw structures.

[0020] In a preferred embodiment, the rotary steerable drilling tool includes a diverter cone disposed within the inner fluid passage and between the rotor and the nozzle seat, and the diverter cone is sleeved outside the lower central shaft.

[0021] In a preferred embodiment, the inner shaft includes a drive shaft, a water cap, an internal adapter, a universal shaft, and a flow path adapter that are sequentially distributed. The lower end of the flow path adapter is connected to the upper piston fixed shaft.

[0022] In a preferred embodiment, a bearing is provided between the inner wall of the tool housing and the drive shaft.

[0023] The present invention provides a drilling string, comprising: a bottom drill string and the above-mentioned rotary steerable drilling tool, wherein the bottom drill string is connected to the lower end of the rotary steerable drilling tool.

[0024] The present invention provides a drilling control method, which adopts the above-mentioned rotary steerable drilling tool. The drilling control method includes: adjusting the rotational speed of the rotor to control the magnitude of the output torque for driving the rotation of the tool housing.

[0025] The features and advantages of the present invention are as follows:

[0026] The inner shaft can be rigidly connected to the upper drill string. During the rotation of the rotor, part of the drilling fluid in the annulus between the tool housing and the wellbore wall is suctioned into the inner fluid passage through the fluid inlet; the drilling fluid entering the inner fluid passage flows through the annulus between the rotor and the stator, and the mechanical energy is transmitted to the tool housing through the stator to generate the driving torque of the tool housing. By adjusting the magnitude of the driving torque transmitted from the screw rotor to the stator tool housing, the conversion between the "separated" state and the "combined" state of the upper drill string and the lower drill string is completed, and the motion state of the bottom drill string completely depends on the result of the competition between the driving torque of the tool housing and the bottom reaction torque.

[0027] With this rotary steerable drilling tool, the upper drill string can move relative to the bottom drill string assembly. When non-directional drilling, the drill string rotates for drilling, and the bottom drill string assembly rotates relative to the upper drill string for compound drilling; when directional drilling, the drill string rotates for drilling, and the bottom drill string assembly slides for drilling. This rotary steerable drilling tool does not need to identify the tool face angle. By directly comparing the reaction torque of the downhole bent screw and the torque generated by the hydraulic clutch control device in the tool, the conversion between the "separated" state and the "combined" state can be achieved, and the operation difficulty is relatively low; it also does not use electrical signal technology, so the working reliability is higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0029] Figure 1 It is a working schematic diagram of the rotary steerable drilling tool provided by the present invention;

[0030] Figure 2 It is a structural schematic diagram of the rotary steerable drilling tool provided by the present invention;

[0031] Figure 3 For Figure 2 It is a partial structural schematic diagram of the upper part of the drive shaft assembly in the shown rotary steerable drilling tool;

[0032] Figure 4 is Figure 2 a partial structural schematic diagram of the lower part of the drive shaft assembly in the rotary steerable drilling tool shown;

[0033] Figure 5 is Figure 2 a structural schematic diagram of the differential pressure control assembly in the rotary steerable drilling tool shown;

[0034] Figure 6 is Figure 2 a structural schematic diagram of the screw assembly in the rotary steerable drilling tool shown;

[0035] Figure 7 is a structural schematic diagram of the nozzle mechanism in the rotary steerable drilling tool provided by the present invention.

[0036] Explanation of the reference numerals in the drawings:

[0037] 101, tool housing; 102, inner shaft; 103, flow channel;

[0038] 110, inner fluid channel; 111, fluid inlet; 112, fluid outlet;

[0039] 1, drive shaft; 2, inner ring of upper TC bearing; 3, outer ring of upper TC bearing;

[0040] 4, drive shaft housing;

[0041] 5, outer bearing locator; 6, inner bearing locator A; 7, inner bearing locator B;

[0042] 8, series bearing;

[0043] 9, outer ring of lower TC bearing; 10, inner ring of lower TC bearing;

[0044] 11, water cap; 12, internal adapter;

[0045] 13, universal shaft;

[0046] 14, universal shaft housing;

[0047] 15, flow path adapter;

[0048] 16, upper piston fixing shaft; 17, upper sealing piston;

[0049] 18, upper fixing shaft housing;

[0050] 19, central shaft; 20, differential pressure control assembly housing; 21, fixing screw;

[0051] 22, nozzle mechanism; 221, nozzle seat; 222, through hole;

[0052] 23. Diverging cone

[0053] 24. Lower central shaft

[0054] 25. Lower central shaft housing

[0055] 26. Stator housing; 261. Stator

[0056] 27. Rotor

[0057] 28. Lower piston fixing shaft; 29. Lower sealing piston

[0058] 30. Lower piston housing Specific implementation mode

[0059] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0060] Solution 1

[0061] The present invention provides a rotary directional drilling tool. As Figures 1-6 shown, the rotary directional drilling tool includes: tool housing 101, inner shaft 102, rotor, upper sealing piston, lower sealing piston 29 and lower piston fixing shaft 28. The inner shaft 102, rotor and lower piston fixing shaft 28 are all arranged in the tool housing 101 and distributed in sequence. Moreover, the inner shaft 102, rotor and lower piston fixing shaft 28 are connected to rotate together, and a flow channel 103 for conveying drilling fluid is provided. A stator 261 that cooperates with the rotor is arranged in the tool housing 101; both the upper sealing piston and the lower sealing piston 29 are arranged in the tool housing 101 and are respectively in sealing cooperation with the inner wall of the tool housing 101; the upper sealing piston is sleeved outside the inner shaft 102 and is located above the rotor, the lower sealing piston 29 is sleeved outside the lower piston fixing shaft 28 and is located below the rotor 27, and an inner fluid channel 110 is formed between the upper sealing piston 17 and the lower sealing piston 29; the tool housing 101 is provided with a fluid inlet 111 and a fluid outlet 112 that are respectively communicated with the inner fluid channel 110. The fluid inlet 111 is located between the lower sealing piston 29 and the rotor, and the fluid outlet 112 is arranged between the upper sealing piston and the rotor.

[0062] The inner shaft 102 can be rigidly connected to the upper drill string and is used to transmit the rotation of the upper drill string to the rotor. The tool housing 101 is rigidly connected to the lower bottom hole assembly. During the rotation of the rotor, a part of the drilling fluid in the annulus between the tool housing 101 and the wellbore is suctioned into the inner fluid passage 110 through the fluid inlet 111; the drilling fluid entering the inner fluid passage 110 flows through the annulus between the rotor and the stator 261, and the mechanical energy is transmitted to the tool housing 101 through the stator 261, generating a driving torque of the tool housing 101. By adjusting the magnitude of the driving torque transmitted from the rotor to the stator 261 and the tool housing 101, the conversion between the "separation" state and the "combination" state of the upper drill string and the lower drill string is completed, and the motion state of the lower drill string completely depends on the result of the competition between the driving torque of the tool housing 101 and the bottom counter torque.

[0063] Through this rotary steerable drilling tool, the upper drill string can move relative to the lower drill string assembly. When non-directional drilling, the drill string rotates for drilling, and the lower drill string assembly rotates relative to the upper drill string for compound drilling; when directional drilling, the drill string rotates for drilling, and the lower drill string assembly slides for drilling. This rotary steerable drilling tool does not need to identify the tool face angle. By directly comparing the counter torque of the downhole bent screw and the torque generated by the hydraulic clutch control device in the tool, the conversion between the "separation" state and the "combination" state can be achieved, and the operation difficulty is relatively low; it also does not need to use electrical signal technology, and the working reliability is higher.

[0064] A part of the drilling fluid in the annulus enters the inner fluid passage 110 through the fluid inlet 111, flows upward in the inner fluid passage 110, and returns to the annulus after being discharged from the fluid outlet 112. The pressure of the drilling fluid drops during the flow in the inner fluid passage 110, that is, there is a pressure difference between the fluid inlet 111 and the fluid outlet 112. Due to the structure of the fluid inlet 111, the fluid outlet 112 and the inner fluid passage 110, the pressure of the drilling fluid will drop during the upward flow process.

[0065] In some embodiments, the rotary steerable drilling tool includes a nozzle mechanism. The nozzle mechanism is arranged in the inner fluid passage 110 and above the rotor. At least part of the fluid in the inner fluid passage 110 flows through the nozzle mechanism, and a pressure drop will occur when the drilling fluid in the inner fluid passage 110 flows through the nozzle mechanism, which is beneficial to increasing the pressure drop of the drilling fluid flowing through the inner fluid passage 110. Preferably, all the fluid in the inner fluid passage 110 passes through the nozzle mechanism.

[0066] Such as Figure 5 and Figure 7As shown, the nozzle mechanism includes a nozzle seat 221. The nozzle seat 221 is sleeved outside the inner shaft 102 and fixedly connected to the tool housing 101. The nozzle seat 221 is provided with a through hole 222 penetrating up and down, and the drilling fluid in the inner fluid passage 110 can flow upward through this passage. Further, the nozzle seat 221 is in sealed cooperation with the outer wall of the inner shaft 102, and the outer wall of the nozzle seat 221 is in sealed cooperation with the inner wall of the tool housing 101, so that the drilling fluid in the inner fluid passage 110 all needs to flow upward through the through hole 222 of the nozzle seat 221, which is beneficial to regulating the pressure drop of the drilling fluid through the nozzle mechanism.

[0067] In one embodiment, the nozzle seat 221 is provided with a plurality of through holes 222, at least one through hole 222 is provided with a pressure nozzle, and a pressure drop is generated during the process that the drilling fluid in the inner fluid passage 110 flows through the nozzle. The plurality of pressure nozzles can be arranged in a ring. Preferably, the rotary steerable drilling tool includes a plurality of nozzle mechanisms, such as Figure 5 As shown, the plurality of nozzle mechanisms are arranged at intervals longitudinally. The pressure drop is relatively large due to the reduction of the internal flow area of the nozzle.

[0068] The plurality of nozzle mechanisms control the pressure drop of the inner fluid passage 110 to control the pressure difference between the inlet and the outlet of the annulus area between the stator 261 and the rotor, and further control the driving torque of the tool housing 101. The nozzle mechanism is provided with a certain number of pressure nozzles. The pressure difference between the inlet and the outlet of the annulus area between the stator 261 and the rotor can be controlled by adjusting the number of nozzle mechanisms, or the installation number of pressure nozzles in the nozzle mechanism, or the diameter of the central hole of the pressure nozzle.

[0069] Further, the tool housing 101 includes a differential pressure control assembly housing 20. The nozzle mechanism is located inside the differential pressure control assembly housing 20, and the nozzle seat 221 is fixedly connected to the inner wall of the differential pressure control assembly housing 20.

[0070] In one embodiment, the rotary steerable drilling tool includes a diverter cone. The diverter cone is arranged inside the inner fluid passage 110 and between the rotor and the nozzle seat 221, and the diverter cone is arranged inside the differential pressure control assembly housing 20. A number of fluid through holes are evenly distributed on the surface of the diverter cone, and the diverter cone can adopt the existing technology.

[0071] As Figures 4-5 shown, the inner shaft 102 includes an upper piston fixed shaft, a central shaft and a lower central shaft. The upper piston fixed shaft, the central shaft and the lower central shaft are distributed in sequence and connected. The upper sealing piston is sleeved outside the upper piston fixed shaft, the nozzle seat 221 is sleeved outside the central shaft, and the diverter cone is sleeved outside the lower central shaft. The tool housing 101 includes an upper fixed shaft housing, a differential pressure control assembly housing and a lower piston housing 30 which are distributed in sequence. The nozzle seat 221 is fixedly connected to the differential pressure control assembly housing and in sealed cooperation.

[0072] As Figure 6 shown, the tool housing 101 includes a stator housing 26 connected to the upper end of the lower piston housing 30. The stator 261 is disposed on the inner wall of the stator housing 26. Preferably, the stator 261 and the stator housing 26 are of an integral structure. In one embodiment, the stator 261 and the rotor are respectively provided with a mating screw structure. Specifically, the rotor is Figure 6 the screw shown, and the stator 261 is adapted to the screw. The stator 261 and the rotor form a screw mechanism.

[0073] In one embodiment, the inner shaft 102 includes a drive shaft, a water cap, an internal adapter, a universal shaft, and a flow path adapter arranged in sequence. As Figures 3-6 shown, the lower end of the flow path adapter is connected to the upper piston fixed shaft. The water cap, the internal adapter, and the fluid adapter are all fluid channels for the drilling fluid inside the tool. Since the rotor rotates with both self-rotation and revolution during the rotation process, the connection through the universal shaft can eliminate the influence of the rotor revolution on the central axis.

[0074] Further, a bearing is provided between the inner wall of the tool housing 101 and the drive shaft. Specifically, the bearing includes a TC bearing (i.e., a cemented carbide bearing) and a string bearing.

[0075] The drive shaft, the central shaft, and the rotor all have central holes for providing a downward flow channel 103 for the drilling fluid inside the tool. The fluid inlet 111 and the fluid outlet 112 are respectively communicated with the inner fluid channel 110 of the drill string and the wellbore annulus for the annulus fluid to enter and exit.

[0076] As Figures 1-3 shown, the bearing, the drive shaft with a central hole, the universal shaft, the transition joint, the flow path joint, the upper sealing piston, the upper piston fixed shaft with a central hole, and the upper fixed shaft housing with the fluid outlet 112 constitute a drive shaft assembly for isolating the rotational movements of the upper and lower drill strings and separating the fluids inside the drill pipe and the annulus.

[0077] As Figure 6 shown, the stator 261, the hollow rotor, the lower piston fixed shaft 28, the lower piston housing with the fluid inlet 111, and the lower sealing piston constitute a screw assembly.

[0078] As Figure 5 shown, the central shaft with a central hole, the differential pressure control housing, the nozzle mechanism, and the lower central shaft constitute a differential pressure control assembly. The nozzle mechanism can control the differential pressure at the inlet and outlet of the screw mechanism, thereby controlling the torque transmitted from the rotor to the stator housing.

[0079] Specifically, the drive shaft is assembled in the drive shaft housing by the outer ring of the lower TC bearing and the inner ring of the lower TC bearing. The string bearing is assembled on the upper end of the outer ring of the lower TC bearing and the inner ring of the lower TC bearing. The inner ring of the upper TC bearing is assembled with the drive shaft. Then, the inner bearing locator A and the inner bearing locator B are assembled with the drive shaft. The inner bearing locator A is of a split structure for easy assembly. The outer ring of the upper TC bearing is assembled onto the drive shaft housing, and the drive shaft is assembled with the drive shaft housing. The water cap is assembled with the inner ring of the lower TC bearing.

[0080] The lower end of the water cap is connected to the adapter sub. The universal shaft is assembled inside the inner adapter sub at the lower end. The flow path adapter sub is assembled to the lower end of the universal shaft. The lower end of the flow path adapter sub is connected to the upper piston fixed shaft. The lower end of the drive shaft housing is sequentially connected to the universal shaft housing and the upper fixed shaft housing. The upper sealing piston 17 is installed in the annulus area between the upper piston fixed shaft and the tool housing 101. The side wall of the upper fixed shaft housing 18 is provided with an opening, serving as the fluid outlet 112 for the fluid flowing through the tool in the annulus between the drill string and the wellbore wall.

[0081] This rotary steerable drilling tool can be connected to the upper drill string at the top and the lower drill string assembly, MWD, bent sub, and bit at the bottom. The upper drill string is connected to the drive shaft 1 at the bottom. The drive shaft 1 is connected to the inner ring 2 of the upper TC bearing at the top. The inner ring 2 of the upper TC bearing is externally connected to the outer ring 3 of the upper TC bearing. The inner ring 2 of the upper TC bearing is connected to the inner bearing locator A 6 at the bottom. The outer ring 3 of the upper TC bearing is connected to the drive shaft housing 4 and the outer bearing locator 5 at the bottom. The inner bearing locator A 6 is connected to the inner bearing locator B 7 at the bottom. The inner bearing locator B 7 and the outer bearing locator 5 are connected to the string bearing 8 at the bottom. The string bearing 8 is connected to the outer ring 9 of the lower TC bearing and the inner ring 10 of the lower TC bearing at the bottom. The drive shaft 1 and the inner ring 10 of the lower TC bearing are connected to the water cap 11 at the bottom. The drive shaft housing 4 is connected to the universal shaft housing 14 at the bottom. The universal shaft housing 14 is connected to the upper fixed shaft housing 18 at the bottom. The water cap 11 is connected to the inner adapter sub 12 at the bottom. The inner adapter sub 12 is connected to the universal shaft 13 at the bottom. The universal shaft 13 is connected to the flow path adapter sub 15 at the bottom. The flow path adapter sub 15 is connected to the upper piston fixed shaft 16 at the bottom. The upper sealing piston 17 is installed in the annulus area between the upper piston fixed shaft 16 and the upper fixed shaft housing 18. The upper piston fixed shaft 16 is connected to the central shaft 19 at the bottom. The central shaft 19 is installed with a diverter cone 23 and is connected to the lower central shaft 24 at the bottom. The upper fixed shaft housing 18 is sequentially connected to the differential pressure control assembly housing 20 and the lower central shaft housing 25 at the bottom. A number of nozzle mechanisms 22 are installed in the annulus between the central shaft 19 and the differential pressure control assembly housing 20, and the nozzle mechanisms 22 are fixed with fixing screws 21. The rotor 27 is connected to the lower central shaft 24 at the top and is externally connected to the stator housing 26. The rotor 27 is connected to the lower piston fixed shaft 28 at the bottom. The lower piston fixed shaft 28 is externally connected to the lower sealing piston 29. The lower sealing piston 29 is externally connected to the lower piston housing 30. The lower piston housing 30 is connected to the bottom hole assembly, MWD, bent sub, and bit at the bottom.

[0082] Drive shaft 1, upper TC bearing inner ring 2, upper TC bearing outer ring 3, drive shaft housing 4, bearing outer positioning part 5, bearing inner positioning part A 6, bearing inner positioning part B 7, series bearing 8, lower TC bearing outer ring 9, lower TC bearing inner ring 10, water cap 11, internal adapter 12, universal shaft 13, flow path adapter 15, upper piston fixed shaft 16, universal shaft housing 14, upper sealing piston 17, upper fixed shaft housing 18 are assembled into a drive shaft assembly. When the upper drill string rotates, the drive shaft assembly will be driven to rotate by the upper drill string, thereby driving the central shaft 19 and the lower central shaft 24 to rotate, realizing that the drive shaft assembly drives the screw assembly to rotate.

[0083] Specifically, the central shaft 19 in the differential pressure control assembly is connected to the lower end of the upper piston fixed shaft 16. The lower part of the central shaft is connected to the lower central shaft 24. The lower end of the upper fixed shaft housing is sequentially connected to the differential pressure control assembly housing and the lower central shaft housing. Several nozzle mechanisms 22 are installed in the annulus area between the central shaft and the tool housing 101. Threaded holes are machined on the surface of the tool housing 101, and the nozzle mechanisms are fixed by screws.

[0084] Specifically, the hollow rotor 27 inside the screw assembly is connected to the lower central shaft 24. The lower end of the hollow rotor is connected to the lower piston fixed shaft 28. The lower end of the lower central shaft housing 25 is sequentially connected to the stator 261 and the lower piston housing 30. The side wall of the lower piston housing 30 is opened as the annulus fluid inlet 111 between the drill pipe and the wellbore wall. A lower sealing piston 29 is installed in the annulus area between the lower piston fixed shaft and the tool housing 101. The rotor 27, stator housing 26, lower piston fixed shaft 28, lower sealing piston 29 and lower piston housing 30 form the screw assembly.

[0085] The drive shaft is rigidly connected to the upper drill string and is used to transfer the rotation of the upper drill string to the rotor of the screw assembly. The bearing group is used to isolate the rotation of the tool housing 101 from the drive shaft and rotor inside the tool. The tool housing 101 is rigidly connected to the lower bottom hole assembly. During the rotation of the rotor, part of the drilling fluid in the annulus between the drill string and the wellbore wall is sucked into the tool. The rotor transfers mechanical energy to the tool housing 101 through the drilling fluid entering the tool, generating the driving torque of the tool housing 101. By adjusting the magnitude of the driving torque transferred from the rotor to the stator housing, the conversion between the "separation" state and the "combination" state of the upper drill string and the lower drill string is completed. The motion state of the lower drill string completely depends on the result of the competition between the driving torque of the tool housing 101 and the bottom reaction torque.

[0086] The specific working process of this rotary steerable drilling tool includes:

[0087] The mud pumped into the well from the surface system is transmitted downward through the central hole inside the tool, enters the annulus area between the drill string and the wellbore after passing through the drill bit. When the upper drill string is stationary and not rotating, most of the mud in the annulus flows upward through the annulus. Similar to a conventional motor, the rotary steerable drilling control tool also has a positive displacement power end. So when the upper drill string rotates at a certain speed, a certain amount of mud in the annulus between the drill string and the wellbore is sucked in and flows through the cavity between the rotor 27 and the stator 261, and then through the screw assembly (the rest of the mud flows through the annulus between the drill string and the wellbore). Thus, a certain pressure difference is generated between the inlet and outlet of the screw assembly of the rotary steerable drilling control tool. This pressure difference can generate a driving torque due to the rotation of the upper drill string, and this driving torque is used to balance the reaction torque resisting the drilling of the lower drilling motor.

[0088] The nozzle mechanism is used to adjust the pressure difference of the screw assembly; after the mud entering the tool flows through the tool, it returns to the annulus between the drill string and the wellbore through the fluid outlet 112 of the upper fixed shaft housing 18 of the tool, so there is no mud loss inside the drill string. The rotational speed at which the driving torque generated by the rotary steerable drilling control tool is equal to the lower screw reaction torque is called the static driving speed. For different formations, the reaction torque generated during drilling is different. The pressure nozzle of the nozzle mechanism 22 can be selected on the ground to generate the desired driving torque, thereby setting the static driving speed. The nozzle mechanism can control the pressure difference at both ends of the screw assembly, and further control the driving torque generated by the tool. This rotary steerable drilling tool realizes the annulus split-flow type hydraulic coupling rotary steerable drilling control.

[0089] Solution Two

[0090] The present invention provides a drilling string, including: a lower drill string and the above-mentioned rotary steerable drilling tool, and the lower drill string is connected to the lower end of the rotary steerable drilling tool. This drilling string has the characteristics and beneficial effects of the above-mentioned rotary steerable drilling tool, which will not be elaborated here.

[0091] Solution Three

[0092] The present invention provides a drilling control method, using the above-mentioned rotary steerable drilling tool. The drilling control method includes: adjusting the rotational speed of the rotor to control the magnitude of the output torque for driving the tool housing 101 to rotate. This drilling control method has the characteristics and beneficial effects of the above-mentioned rotary steerable drilling tool, which will not be elaborated here.

[0093] During the rock-breaking drilling process, the drill bit is subject to the reaction torque (counter-torque) of the formation. The counter-torque is mainly determined by factors such as formation conditions, drilling pressure, torque, and rotational speed, and its direction is opposite to the direction of the driving torque of the tool housing 101. The drill string between the tool and the drill bit is subject to the action of the friction torque, and the direction of this friction torque is always opposite to the direction of the movement or the trend of movement of the tool housing 101. Considering the above situation, in this drilling control method, when the rotational speed of the rotor is adjusted to ensure that the driving torque transmitted to the stator housing through the drilling fluid entering the tool is greater than the counter-torque received by the drill bit, the lower drill string rotates together with the upper drill string, being in the "combined" state, and the drill string enters the compound drilling state. When the driving torque of the stator housing is less than the counter-torque received by the drill bit, the lower drill string cannot rotate, being in the "separated" state, and the drill string enters the directional drilling state. In the directional drilling state, when the counter-torque of the lower drill bit fluctuates, the friction torque can play a role in stabilizing the movement state of the tool housing 101, keeping the tool in the "separated" state.

[0094] Specifically, the ground controls the rotational speed of the upper drill string to drive the rotation of the rotor of the screw assembly. During the rotation of the rotor, the screw assembly generates a pumping and suction effect on the fluid in the annulus between the drill string and the wellbore wall, causing part of the fluid in the annulus between the drill string and the wellbore wall to enter the interior of the tool of the present invention. The screw assembly can be equivalently regarded as a screw pump, which generates a pumping and pressure-boosting effect on the fluid entering the interior of the tool, forming a high-pressure chamber at the end of the screw assembly, converting mechanical energy into hydraulic energy. The fluid entering the tool, after passing through the nozzle mechanism, has a pressure drop, and the hydraulic energy is converted into the mechanical energy of the tool housing 101, thereby generating an output torque that drives the rotation of the tool housing 101.

[0095] The calculation model of the driving torque is as shown in Equation 1:

[0096]

[0097] Where, M 1 is the output torque of the tool, Q 1 is the flow rate of the fluid entering the interior of the tool, Δp 1 is the pressure increase of the fluid entering the screw assembly, n 1 is the rotational speed of the rotor of the screw assembly, n 2 is the rotational speed of the housing of the screw assembly, η p is the volumetric efficiency of the screw assembly.

[0098] Q 1 = Q - Q 2 (2)

[0099] Where, Q is the total flow rate in the annulus between the drill string and the wellbore wall, Q 2 is the flow rate of the remaining fluid in the annulus between the drill string and the wellbore wall.

[0100] Δp 1= Δp 2 -Δp 3 (3)

[0101] wherein, Δp 2 is the pressure drop of the fluid entering the tool flowing through the nozzle assembly, and Δp 3 is the pressure drop of the fluid in the annulus between the drill string and the wellbore during the process of flowing through the inlet and outlet of the tool.

[0102] The magnitude of the output torque is mainly determined by the flow rate of the fluid entering the tool and the pressure increase of the fluid by the screw assembly; the flow rate of the fluid entering the tool is determined by the rotational speed difference between the rotor of the screw assembly and the tool housing 101; the pressure increase of the fluid by the screw assembly is determined by the pressure drop of the fluid passing through the nozzle assembly and the pressure drop of the fluid in the annulus between the drill string and the wellbore. During the working process, the magnitude of the output torque is adjusted by adjusting the rotational speed and flow rate of the rotor. The output torque of the tool competes with the reaction torque of the lower drill string. When the output torque converted from the rotational speed of the upper drill string is greater than the reaction torque of the lower drill string of the tool, the lower drill string is driven to rotate to form compound drilling; when the output torque converted from the rotational speed of the upper drill string is less than or equal to the reaction torque of the lower drill string of the tool, the lower drill string does not rotate to form directional drilling.

[0103] The above are only several embodiments of the present invention. Those skilled in the art can make various changes or modifications to the embodiments of the present invention without departing from the spirit and scope of the present invention according to the content disclosed in the application documents.

Claims

1. A rotary directional drilling tool, characterized in that, it comprises: a tool housing, an inner shaft, a rotor, an upper sealing piston, a lower sealing piston and a lower piston fixed shaft. The inner shaft, the rotor and the lower piston fixed shaft are all arranged in the tool housing and distributed in sequence. Moreover, the inner shaft, the rotor and the lower piston fixed shaft are connected to rotate together and are provided with a flow channel for conveying drilling fluid. A stator matched with the rotor is arranged in the tool housing; the upper sealing piston and the lower sealing piston are both arranged in the tool housing and are respectively in sealing cooperation with the inner wall of the tool housing; the upper sealing piston is sleeved outside the inner shaft and is located above the rotor. The lower sealing piston is sleeved outside the lower piston fixed shaft and is located below the rotor. An inner fluid channel is formed between the upper sealing piston and the lower sealing piston; the tool housing is provided with a fluid inlet and a fluid outlet respectively communicated with the inner fluid channel. The fluid inlet is located between the lower sealing piston and the rotor. The fluid outlet is arranged between the upper sealing piston and the rotor; the rotary directional drilling tool comprises a nozzle mechanism. The nozzle mechanism is arranged in the inner fluid channel and is located above the rotor. At least part of the fluid in the inner fluid channel flows through the nozzle mechanism; the drilling fluid flowing upward in the annulus can enter the inner fluid channel from the fluid inlet, flow through the annulus between the rotor and the stator and the nozzle mechanism, and then flow out from the fluid outlet to generate a driving torque on the tool housing.

2. The rotary directional drilling tool according to claim 1, characterized in that, the nozzle mechanism comprises a nozzle seat. The nozzle seat is sleeved outside the inner shaft and is fixedly connected to the tool housing. The nozzle seat is provided with a through hole penetrating up and down.

3. The rotary directional drilling tool according to claim 2, characterized in that, the nozzle seat is in sealing cooperation with the outer wall of the inner shaft, and the outer wall of the nozzle seat is in sealing cooperation with the inner wall of the tool housing.

4. The rotary directional drilling tool according to claim 2, characterized in that, the nozzle seat is provided with a plurality of the through holes, and at least one of the through holes is provided with a pressure nozzle.

5. The rotary directional drilling tool according to any one of claims 1-4, characterized in that, the rotary directional drilling tool comprises a plurality of the nozzle mechanisms arranged at intervals longitudinally.

6. The rotary directional drilling tool according to claim 2, characterized in that, the inner shaft comprises an upper piston fixed shaft, a central shaft and a lower central shaft. The upper piston fixed shaft, the central shaft and the lower central shaft are distributed in sequence and are connected. The upper sealing piston is sleeved outside the upper piston fixed shaft, and the nozzle seat is sleeved outside the central shaft.

7. The rotary directional drilling tool according to claim 6, characterized in that, the tool housing comprises an upper fixed shaft housing, a differential pressure control assembly housing and a lower piston housing which are distributed in sequence. The nozzle seat is fixedly connected to the differential pressure control assembly housing and is in sealing cooperation.

8. The rotary directional drilling tool according to claim 7, characterized in that, The tool housing includes a stator housing connected to the upper end of the lower piston housing. The stator is disposed in the stator housing, and the stator and the rotor are respectively provided with matching screw structures.

9. The rotary directional drilling tool according to claim 6, wherein, the rotary directional drilling tool includes a diverter cone. The diverter cone is disposed in the inner fluid passage and located between the rotor and the nozzle seat, and the diverter cone is sleeved outside the lower central shaft.

10. The rotary directional drilling tool according to claim 6, wherein, the inner shaft includes a drive shaft, a water cap, an internal adapter, a universal shaft, and a flow path adapter that are sequentially distributed. The lower end of the flow path adapter is connected to the upper piston fixed shaft.

11. The rotary directional drilling tool according to claim 10, wherein, a bearing is provided between the inner wall of the tool housing and the drive shaft.

12. A drilling string, wherein, it includes: a bottom hole assembly and the rotary directional drilling tool according to any one of claims 1-11. The bottom hole assembly is connected to the lower end of the rotary directional drilling tool.

13. A drilling control method, wherein, the rotary directional drilling tool according to any one of claims 1-11 is adopted. The drilling control method includes: adjusting the rotational speed of the rotor to control the magnitude of the output torque for driving the rotation of the tool housing.

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