Rotary steerable drilling tool

Abstract

The present invention provides a rotary steerable drilling tool, which includes a drill bit, a steering section, a flexible drill string, a propulsion mechanism and an electric drive actuator. The steering section includes a load-bearing body, the drill bit is connected to the lower part of the load-bearing body, and a steering mechanism is connected to the load-bearing body; the flexible drill string includes a torque transmission string and a pressure-bearing hose, and the lower end of the torque transmission string is connected to the upper end of the load-bearing body; the propulsion mechanism is connected to the load-bearing body and communicates with the flexible drill string, and the propulsion mechanism can drive the drill bit to drill or pull the flexible drill string forward; the electric drive actuator is electrically connected to the steering mechanism, and the electric drive actuator can control the action of the steering mechanism. The rotary steerable drilling tool of the present invention can achieve short-radius directional drilling, and the propulsion mechanism can well assist the flexible drill string to advance or push the drill bit to drill, so as to achieve short-radius steering drilling with a certain wellbore extension length.

Description

Technical Field

[0001] The present invention relates to the technical fields of drilling technology and oil and gas exploitation technology, and particularly relates to a rotary steerable drilling tool. Background Art

[0002] A large amount of drilling technology is required for the exploration and development of underground material resources and space resources. The existing steerable drilling technologies mainly include downhole motor steerable drilling technology and rotary steerable drilling technology. The maximum build rate that can be achieved by the above technologies generally does not exceed 15° / 30 m, and neither can achieve controllable trajectory short-radius steerable drilling or continue to conduct steerable drilling at the bottom end of an existing short-radius well section. There are also many radial or short-radius drilling technologies in the prior art that cannot effectively control the wellbore trajectory, and the utilization effect of such technologies on underground resources is not good. Summary of the Invention

[0003] The object of the present invention is to provide a rotary steerable drilling tool capable of achieving a certain wellbore extension length.

[0004] To achieve the above object, the present invention provides a rotary steerable drilling tool, which includes:

[0005] A drill bit;

[0006] A steering section, which includes a bearing body, the drill bit is connected to the lower part of the bearing body, and a steering mechanism is connected to the bearing body;

[0007] A flexible drill string, which includes a torque transmission train and a pressure-bearing hose, the torque transmission train is disposed inside the pressure-bearing hose, or the pressure-bearing hose is disposed inside the torque transmission train, and the lower end of the torque transmission train is connected to the upper end of the bearing body;

[0008] A propulsion mechanism, which is connected to the bearing body and communicates with the flexible drill string, and the propulsion mechanism can drive the drill bit to drill or pull the flexible drill string forward;

[0009] An electric drive actuator, which is electrically connected to the steering mechanism, and the electric drive actuator can control the action of the steering mechanism.

[0010] The rotary steerable drilling tool as described above, wherein the propulsion mechanism includes at least two reverse nozzles arranged at intervals along the circumferential direction of the bearing body, and the inlets of the reverse nozzles are connected to the through-flow channel inside the flexible drill string.

[0011] The rotary steerable drilling tool as described above, wherein the propulsion mechanism includes a drainage nozzle and a sealing structure, the sealing structure has a throat, the drainage nozzle is arranged below the throat, and the throat is communicated with the through-flow channel inside the flexible drill string through the drainage nozzle.

[0012] The rotary steerable drilling tool as described above, wherein the torque transmission train includes a plurality of torque transmission short joints connected in sequence from top to bottom, and adjacent two torque transmission short joints are rotatably connected through a variable-angle force transmission structure, and the lowermost torque transmission short joint is connected to the bearing body.

[0013] The rotary steerable drilling tool as described above, wherein the deflection limit between any two torque transmission short joints is more than 2°.

[0014] The rotary steerable drilling tool as described above, wherein the length of the torque transmission short joint is less than or equal to 5 times the diameter of the bearing body.

[0015] The rotary steerable drilling tool as described above, wherein the length of the torque transmission short joint is 30% to 300% of the diameter of the bearing body.

[0016] The rotary steerable drilling tool as described above, wherein the variable-angle force transmission structure includes a universal joint and a sleeve sleeved outside the universal joint, a gap is formed between the sleeve and the universal joint to form a deflection space, and the universal joint can deflect relative to the axis of the sleeve by 0.5° to 15° within the deflection space.

[0017] The rotary steerable drilling tool as described above, wherein the variable-angle force transmission structure includes a ball seat and a ball head, a torque transmission groove is provided on one of the ball head and the ball seat, a torque transmission pin is provided on the other of the ball head and the ball seat, and the torque transmission pin is rotatably received in the torque transmission groove.

[0018] The rotary steerable drilling tool as described above, wherein the pressure-bearing hose is a composite material pipe, a rubber pipe or a slotted pipe with a sealing material filled in the slots.

[0019] The rotary steerable drilling tool as described above, wherein a diameter protection structure is connected to the outside of the bearing body, and the diameter protection structure includes scraping blade wings or centralizers.

[0020] The rotary steerable drilling tool as described above, wherein the guiding mechanism includes at least three accommodation cavities arranged on the bearing body at intervals along the circumferential direction of the bearing body, a driving piston capable of telescoping in the radial direction of the bearing body is arranged in the accommodation cavity, the driving piston can abut against the well wall, and the telescoping of the driving piston can drive the bearing body to deflect in a preset direction.

[0021] The rotary steerable drilling tool as described above, wherein the electric drive actuator includes a motor and a rotary valve, the rotary valve includes a rotary valve disc and a rotary valve seat, the rotary valve seat is fixedly connected to the bearing body, the rotary valve seat is provided with a plurality of communication holes respectively corresponding to each of the accommodation cavities one by one, the rotary valve disc is electrically connected to the motor, and the motor can drive the rotary valve disc to rotate relative to the rotary valve seat.

[0022] The rotary steerable drilling tool as described above, wherein when reverse circulation drilling is adopted, the propulsion mechanism is a packer ring, the outer diameter of the packer ring is 90%-110% of the outer diameter of the drill bit, and the packer ring can be fitted to the inner wall surface of the wellbore or maintain a preset gap.

[0023] The rotary steerable drilling tool as described above, wherein the rotary steerable drilling tool further includes a control sub, the control sub is connected between the steering sub and the flexible drill string, or the control sub is connected at any position in the flexible drill string, or the control sub is connected to the upper end of the flexible drill string, and a control circuit is provided in the control sub, and the control circuit is electrically connected to the electric drive actuator through a jumper line.

[0024] The rotary steerable drilling tool as described above, wherein the rotary steerable drilling tool further includes a downhole power supply, the downhole power supply is connected to the upper end of the flexible drill string, and the downhole power supply is electrically connected to the control circuit.

[0025] Compared with the prior art, the advantages of the present invention are as follows:

[0026] The rotary steerable drilling tool of the present invention is mainly used for short-radius radius steering drilling with a diameter range of 0.0254 mm to 0.127 m and a turning radius of less than 10 m. The flexible drill string is fed by pulling through the propulsion mechanism. The pressure-bearing hose in the flexible drill string bears the tension and plays a sealing role. The torque transmission train only needs to achieve the simple function of torque transmission, greatly simplifies the complexity of the torque transmission train, and greatly reduces the diameter size of the flexible drill string, and can realize drill string feeding, drill string pulling and torque transmission within a smaller diameter range. By setting the steering mechanism, the steering mechanism can drive the drill bit to deflect in a preset direction under the condition of rotation to change the wellbore trajectory, so as to realize short-radius directional drilling; by setting the propulsion mechanism, it can well assist the flexible drill string to advance or push the drill bit to drill, so as to realize small-diameter short-radius steering drilling with a certain wellbore extension length. The present invention uses a composite material pipe, a rubber pipe or a slotted pipe with a sealing material filled in the slot as the pressure-bearing hose, and maximally controls the weight of the flexible drill string, so that it can be smoothly pulled by the propulsion mechanism. Description of the Drawings

[0027] The following drawings are only intended to schematically illustrate and explain the present invention, and do not limit the scope of the present invention. Among them:

[0028] Figure 1 is a schematic structural diagram of the rotary steerable drilling tool of the present invention;

[0029] Figure 2 is Figure 1 the enlarged structural diagram of part A in

[0030] Figure 3 is another schematic structural diagram of the rotary steerable drilling tool of the present invention;

[0031] Figure 4 is Figure 3 the enlarged structural diagram of part B in

[0032] Figure 5 is a schematic structural diagram of a closed structure;

[0033] Figure 6 is a first schematic structural diagram of a flexible drill string;

[0034] Figure 7 is a second schematic structural diagram of a flexible drill string;

[0035] Figure 8 is a third schematic structural diagram of a flexible drill string;

[0036] Figure 9 is another schematic structural diagram of the rotary steerable drilling tool of the present invention.

[0037] Explanation of the reference numerals in the drawings:

[0038] 1. Bit; 11. Front cutting blade; 12. Front nozzle;

[0039] 2. Steering section; 21. Load-bearing body; 211. Steering mechanism; 2111. Accommodation cavity; 2112. Driving piston; 212. Gauge protection structure; 22. Packing ring;

[0040] 3. Flexible drill string; 31. Torque transmission train; 311. Torque transmission sub-joint; 312. Variable-angle force transmission structure; 3123. Ball head; 3124. Ball seat; 3125. Torque transmission groove; 3126. Torque transmission pin; 3127. Seal; 32. Pressure-bearing hose; 33. Through-flow channel;

[0041] 4. Propulsion mechanism; 41. Reverse nozzle; 42. Drainage nozzle; 43. Closed structure; 431. Throat;

[0042] 5. Electric drive actuator; 51. Electric motor; 52. Rotary valve; 521. Rotary valve disc; 522. Rotary valve seat;

[0043] 6. Drive drill string;

[0044] 7. Deflector;

[0045] 8. Anchoring device;

[0046] 9. Control sub; 91. Control circuit; 92. Jump wire;

[0047] 10. Downhole power supply;

[0048] Z. Main wellbore;

[0049] F. Branch wellbore. Detailed implementation manner

[0050] For a clearer understanding of the technical solution, purpose and effect of the present invention, the specific implementation manner of the present invention will be described below with reference to the accompanying drawings. Herein, "front" and "rear" in the present invention do not represent specific orientations, but only represent the relative positional relationship of the ultra-short radius rotary steerable tool itself; "rear" and "upper" have the same meaning, "front" and "lower" have the same meaning; "ultra-short radius" mainly refers to the case where the radius is less than 10 meters, but the specific value of the turning radius is not a limiting content in the present invention; in the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0051] As Figure 1 、 Figure 2 、 Figure 3 and Figure 4 shown, the present invention provides a rotary steerable drilling tool, which includes a drill bit 1, a steering section 2, a flexible drill string 3, a propulsion mechanism 4 and an electric drive actuator 5, wherein:

[0052] The drill bit 1 may include a front cutting blade 11 with cutting ability and a front nozzle 12 with jet rock breaking ability. During the drilling process, the main drilling power comes from the weight on bit and torque transmitted to the front cutting blade 11 by the flexible drill string 3, and the secondary power is the jet rock breaking by the high-pressure water jet through the front nozzle 12. The front nozzle 12 can play the role of timely carrying the cuttings to avoid repeated crushing and timely cooling the front cutting blade 11. Or, the main drilling power comes from the jet rock breaking by the high-pressure water jet through the front nozzle 12, and the secondary power is the weight on bit and torque transmitted to the front cutting blade 11 by the flexible drill string 3. The front cutting blade 11 can play a role in further leveling the wellbore. Specifically, when the angle set by the front nozzle 12 is small, the size of the new wellbore formed by the jet is relatively small. On the contrary, when the angle set by the front nozzle 12 is large, the size of the new wellbore formed by the jet is also relatively large. Since the wellbore trajectory formed by the water jet is not flat, the wellbore formed solely by jet rock breaking is not conducive to the working stability of the steering actuator, which will cause difficulties in stable steering and fine control of the wellbore trajectory. The front cutting blade 11 can play a role in assisting in scraping the wellbore wall and leveling the wellbore, which is conducive to ensuring the stability of directional drilling and realizing the fine control of the wellbore trajectory. The drill bit 1 mainly using the front cutting blade 11 for rock breaking is suitable for the case of a larger wellbore diameter, and the drill bit 1 mainly using the jet nozzle for rock breaking is suitable for a smaller wellbore diameter. The specific structures of the front cutting blade 11 and the front nozzle 12 are prior arts and will not be elaborated here;

[0053] The steering joint 2 includes a load-bearing body 21. The drill bit 1 is connected to the lower part of the load-bearing body 21. A steering mechanism 211 is connected to the load-bearing body 21. The steering mechanism 211 can drive the drill bit 1 and the steering joint 2 to deflect in a preset direction, thereby changing the wellbore trajectory to achieve a short build-up rate;

[0054] The flexible drill string 3 includes a torque transmission string 31 and a pressure-bearing hose 32. The torque transmission string 31 is disposed inside the pressure-bearing hose 32, or the pressure-bearing hose 32 is disposed inside the torque transmission string 31. The lower end of the torque transmission string 31 is connected to the upper end of the load-bearing body 21. The torque transmission string 31 is used to transmit the torque required for drilling and a small part of the weight on bit, and the inside of the flexible drill string 3 is connected to the inside of the load-bearing body 21 to form a flow channel;

[0055] The propulsion mechanism 4 is connected to the load-bearing body 21 and is in communication with the flexible drill string 3. The propulsion mechanism 4 can drive the drill bit 1 to drill or pull the flexible drill string 3 forward. Since the turning radius is extremely short, it is necessary to maximize the flexibility of the drill string to adapt to the extremely small turning radius. As the flexibility of the flexible drill string 3 continuously increases, its ability to transmit the weight on bit decreases. Therefore, the propulsion mechanism 4 can well assist the flexible drill string 3 to move forward;

[0056] The electric drive actuator 5 is electrically connected to the guiding mechanism 211. The electric drive actuator 5 can control the movement of the guiding mechanism 211, making it simple and convenient to drive the guiding mechanism 211 to achieve rotary guiding operation.

[0057] For the rotary guiding drilling tool of the present invention, by arranging the guiding mechanism 211, the guiding mechanism 211 can drive the drill bit 1 to deflect in a preset direction under the rotating condition, so as to change the wellbore trajectory, thereby achieving a short build rate; by arranging the propulsion mechanism 4, it can well assist the flexible drill string 3 to advance or push the drill bit 1 to drill, thereby achieving short-radius guiding drilling with a certain wellbore extension length.

[0058] In an embodiment of the present invention, as Figure 1 and Figure 2 shown, the propulsion mechanism 4 includes at least two reverse nozzles 41 arranged at intervals along the circumferential direction of the bearing body 21. The inlet of the reverse nozzle 41 is connected to the through-flow channel 33 inside the flexible drill string 3. High-pressure water flow can enter the reverse nozzle through the channel. The reverse nozzle 41 provides all or part of the axial force for rock breaking and / or pulling the flexible drill string 3 forward. This axial force refers to the axial direction along the guiding section 2. The reverse nozzle 41 uses the drilling circulating medium conveyed by the flexible drill string 3 to achieve reverse jetting to provide the forward drilling power. Further, the reverse nozzle 41 cooperates with the drill bit 1. Since the forward resistance suffered by the drill bit 1 during drilling is opposite to the axial drag force provided by the reverse nozzle 41, when the drill bit 1 uses the front blade 11 as the main power, the hydraulic energy is only used as an auxiliary. At this time, the hydraulic energy of the reverse nozzle 41 mainly plays the role of cleaning the wellbore; when the drill bit 1 uses the jet nozzle as the main power, the hydraulic energy should play the role of breaking the formation. The main function of the reverse nozzle 41 is to overcome the forward resistance and provide sufficient axial drag force for extended drilling. Preferably, 3 to 8 reverse nozzles 41 are arranged along the circumferential direction of the bearing body 21.

[0059] In another embodiment of the present invention, as Figure 3 、 Figure 4 and Figure 5 shown, the propulsion mechanism 4 includes a drainage nozzle 42 and a sealing structure 43. The sealing structure 43 is sleeved outside the bearing body 21. The sealing structure 43 has a throat 431. The drainage nozzle 42 is connected to the lower end of the throat 431. The inlet of the throat 431 is connected to the flexible drill string 3 through the drainage nozzle 42, that is, the throat 431 is connected to the through-flow channel 33 through the drainage nozzle 42. The drainage nozzle 42 can jet high-pressure fluid towards the extending direction of the throat 431, and use the fluid jetted by the drainage nozzle 42 to drive the fluid below the sealing structure 43 to flow above the sealing structure 43, so as to generate a pressure difference between the upper and lower parts of the sealing structure 43. This pressure difference can push the drill bit 1 forward.

[0060] In an implementation manner of the present invention, asFigure 1 , Figure 3 , Figure 6 and Figure 7 As shown in Figure 1 , Figure 3 , Figure 6 and Figure 7 , the torque transmission train 31 includes a plurality of torque transmission subsections 311 connected in sequence from top to bottom. Adjacent torque transmission subsections 311 are rotatably connected by a variable-angle force transmission structure 312, that is, the torque transmission train 31 has a hinge structure. The torque transmission subsection 311 at the bottom is connected to the bearing body 21. Since the propulsion device can propel the drill bit 1 to break rock and the pressure-bearing hose 32 can bear the axial force, the torque transmission subsection 311 can transmit the torque for driving the drill bit 1 to rotate.

[0061] Furthermore, the length of the torque transmission subsection 311 is less than or equal to 5 times the diameter of the bearing body 21, and the deflection limit between any torque transmission subsections 311 is above 2°, so as to fully ensure that the torque transmission subsection 311 train has sufficient flexibility.

[0062] Furthermore, the length of the torque transmission subsection 311 is 30% - 300% of the diameter of the bearing body 21.

[0063] Furthermore, the variable-angle force transmission structure 312 includes a universal joint and a sleeve sleeved outside the universal joint. There is a gap between the sleeve and the universal joint to form a deflection space. The universal joint can deflect 0.5° - 15° relative to the axis of the sleeve. By restricting the deflection angle of the universal joint through the sleeve, it is possible to prevent the variable-angle force transmission structure 312 from buckling excessively during the drill pressure torque transmission process, which may hinder the drill pressure torque transmission, so that the drill pressure torque can be transmitted smoothly.

[0064] Alternatively, the variable-angle force transmission structure 312 includes a ball seat 3124 and a ball head 3123. A torque transmission groove 3125 is provided on one of the ball head 3123 and the ball seat 3124, and a torque transmission pin 3126 is provided on the other. The torque transmission pin 3126 is rotatably received in the torque transmission groove 3125 to achieve torque transmission, and a seal 3127 is provided between the torque transmission pin 3126 and the torque transmission groove 3125. The seal 3127 can prevent the drilling fluid in the annulus from flowing into the drilling fluid inside the flexible drill string 3.

[0065] In an embodiment of the present invention, as shown in Figure 6 and Figure 7 , the pressure-bearing hose 32 is a composite material pipe, a rubber pipe or a slotted pipe. Among them, when the torque transmission train 31 is a slotted pipe, the slots of the slotted pipe are filled with sealing materials.

[0066] Furthermore, as shown in Figure 8As shown in the figure, when reverse circulation drilling is adopted, the propulsion mechanism 4 is a packer ring 22. The outer diameter of the packer ring is 90% - 110% of the outer diameter of the drill bit 1. The packer ring 22 can fit against the inner wall surface of the wellbore or maintain a preset (smaller) gap. The drilling circulation medium passes through the annulus between the rotary steerable drilling tool and the wellbore and then passes through the packer ring 22, and further returns through the through-flow channel 33 inside the flexible drill string 3.

[0067] It should be noted that the packer ring 22 includes a rubber ring to achieve close contact between the packer ring and the well wall. During reverse circulation drilling, since the packer ring 22 occupies the annular space between the rotary steerable drilling tool and the well wall, a large resistance will be generated when the drilling circulation medium flows through the packer ring 22. A large throttling pressure difference will be generated between the upper end and the lower end of the packer ring 22, and this throttling pressure difference will drive the drill bit 1 forward. In this embodiment, the packer ring 22 is sleeved on the outside of the bearing body 21. As a better option, a centralizing bearing is provided between the packer ring 22 and the bearing body 21 so that the packer ring can not rotate with the rotary steerable drilling tool, which is used to reduce the wear of the packer ring 22.

[0068] In an embodiment of the present invention, as Figure 2 and Figure 4 shown, a gauge protection structure 212 is connected to the outside of the bearing body 21. The gauge protection structure 212 includes scraping blades or centralizers. The external dimensions of the scraping blades should be basically the same as those of the front blades 11. In small-diameter wellbores, it can also ensure that the flexible drill string 3 can pass through the short - very short radius wellbore smoothly and complete the deep drilling of the extended section. The centralizer can be used as an effective fulcrum during the rotary steering process to ensure stable steering.

[0069] In an embodiment of the present invention, as Figure 2 and Figure 4 shown, the guiding mechanism 211 includes at least three receiving cavities 2111 arranged at intervals along the circumferential direction of the bearing body 21 on the bearing body 21. Preferably, the receiving cavities 2111 are equally spaced. A driving piston 2112 that can expand and contract along the radial direction of the bearing body 21 is arranged in the receiving cavity 2111. The driving piston 2112 can abut against the well wall. Specifically, the driving piston 2112 can directly abut against the well wall or indirectly abut against the well wall through a pushing member. The expansion and contraction of the driving piston 2112 can drive the bearing body 21 to deflect in a preset direction. Specifically, by adjusting the expansion and contraction amounts of the driving pistons 2112, the thrust exerted by each driving piston on the well wall can be adjusted. The well wall will act on the bearing body 21 through the driving piston 2112 with a reaction force, so that the bearing body 21 drives the drill bit 1 to deflect a certain angle relative to the well wall, thereby changing the wellbore trajectory.

[0070] Further, the electric drive actuator 5 includes a motor 51 and a rotary valve 52. The rotary valve 52 includes a rotary valve disc 521 and a rotary valve seat 522. The rotary valve seat 522 is fixedly connected to the bearing body 21. The rotary valve seat 522 is provided with a plurality of communication holes respectively corresponding to the accommodating cavities 2111 one by one. The rotary valve disc 521 is electrically connected to the motor 51. The motor 51 can drive the rotary valve disc 521 to rotate relative to the rotary valve seat 522, so that the through holes on the rotary valve seat 522 periodically supply high-pressure drilling fluid to the corresponding accommodating cavities 2111, so as to periodically generate thrust on the driving piston 2112.

[0071] In an embodiment of the present invention, as Figure 9 shown, when laterally drilling a branch well inside a wellbore, the rotary steerable drilling tool further includes a drive drill string 6. The drive drill string 6 drives the rotary steerable drilling tool to perform rotary drilling. The rotary steerable drilling tool is supported by a whipstock 7 and turns from the main wellbore into the branch wellbore. An anchoring device 8 is provided below the whipstock 7. The anchoring device 8 can be connected to the inner wall surface of the wellbore to prevent the whipstock 7 from slipping. The drive drill string 6 is connected to the upper end of the flexible drill string 3. The drive drill string 6 can transmit the drilling power to the drill bit 1 through the flexible drill string 3. The specific structure of the drive drill string 6 is prior art and will not be described in detail here.

[0072] In an embodiment of the present invention, as Figure 1 and Figure 3 shown, the rotary steerable drilling tool further includes a control sub 9. The control sub 9 is connected between the steering sub 2 and the flexible drill string 3, or the control sub 9 is connected to any position in the flexible drill string 3, or the control sub 9 is connected to the upper end of the flexible drill string 3. Since the diameter of the rotary steerable drilling tool should be less than 0.1016 m due to the assistance of the propulsion device to advance the flexible drill string 3, it is not convenient for the control sub 9 to enter the branch wellbore F together with the rotary steerable drilling tool. The advantage of the present invention is that during the construction process, the control sub 9 does not need to enter the branch wellbore F, so there is no need to consider the flexibility of the control sub 9; a control circuit 91 is provided in the control sub 9. The control circuit 91 is electrically connected to the electric drive actuator 5 through a jumper line 92 to control the drive guiding mechanism 211 of the electric drive actuator 5 to achieve the rotary steering function.

[0073] Furthermore, the rotary steerable drilling tool also includes a downhole power supply 10, which is connected to the upper end of the flexible drill string 3. The downhole power supply 10 is electrically connected to the control circuit 91. The downhole power supply 10 can generate electricity by driving the downhole generator with a downhole turbine, or by driving the downhole generator with a downhole screw, or by directly supplying electricity with an downhole battery. The above-mentioned methods of generating electricity all require a large amount of space. Therefore, the present invention arranges the downhole power supply 10 above the flexible drill string 3. During the construction process, the downhole power supply 10 does not enter the branch wellbore F. In this way, there is no need to consider the flexibility of the downhole power supply 10, and it can well power the electric drive actuator 5 in the flexible drill string 3 and / or the supporting body 21.

[0074] It should be noted that the method of realizing the side drilling of an extremely short radius branch well from any position Z of the main wellbore is an existing technology. In the existing technology, the process of the extremely short radius side drilling can guide the wellbore trajectory of the extremely short radius well section to a certain extent by relying on the orientation of the bevel 7 and the angle between the guiding inclined surface of the bevel 7 and the Z axis of the main wellbore. However, after completing the side drilling of the extremely short radius branch, in order to achieve the purpose of maximizing contact with the formation, it is necessary to continue to complete the extension section of the extremely short radius branch well section. The extension displacement of the extension section and the wellbore trajectory accuracy directly determine the economic benefits of the extremely short radius branch well (including the extremely short radius well section and its extension section). Therefore, the main purpose of the present invention is to solve the wellbore trajectory control problem of the extension section of the extremely short radius branch well section, but it does not mean that the content of the present invention is only used for the extension section of the extremely short radius branch well section.

[0075] To sum up, the rotary directional drilling tool of the present invention, by setting a guiding mechanism, can drive the drill bit to deflect in a preset direction under rotation conditions to change the wellbore trajectory, thereby realizing short-radius directional drilling; by setting a propulsion mechanism, it can assist the flexible drill string to advance or push the drill bit to drill, thereby realizing small-diameter short-radius directional drilling with a certain wellbore extension length.

[0076] The above description is only an illustrative embodiment of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention should fall within the scope of protection of the present invention. It should also be noted that the various components of the present invention are not limited to the above-mentioned overall application. The various technical features described in the specification of the present invention can be selected one by one or multiple features can be used in combination according to actual needs. Therefore, the present invention naturally covers other combinations and specific applications related to the invention point of this case.

Claims

1. A rotary steerable drilling tool, characterized in that, The rotary steerable drilling tool includes: A drill bit; the drill bit includes a front cutting blade with cutting ability and a front nozzle with jet rock-breaking ability. During drilling, the main drilling power comes from the weight on bit and torque transmitted by the flexible drill string to the front cutting blade, and the secondary power is the jet rock-breaking by high-pressure water jet through the front nozzle. The front nozzle is used to carry rock in time to avoid repeated crushing and cool the front cutting blade in time. Or, the main drilling power comes from the jet rock-breaking by high-pressure water jet through the front nozzle, and the secondary power is the weight on bit and torque transmitted by the flexible drill string to the front cutting blade. The front cutting blade is used to flatten the wellbore; A steering section, which includes a bearing body. The drill bit is connected to the lower part of the bearing body, and a steering mechanism is connected to the bearing body; A flexible drill string, which includes a torque transmission string and a pressure-bearing hose. The torque transmission string is disposed inside the pressure-bearing hose, or the pressure-bearing hose is disposed inside the torque transmission string. The lower end of the torque transmission string is connected to the upper end of the bearing body; A propulsion mechanism, which is connected to the bearing body and communicates with the flexible drill string. The propulsion mechanism can drive the drill bit to drill or pull the flexible drill string forward; The propulsion mechanism includes a drainage nozzle and a sealing structure. The sealing structure has a throat. The drainage nozzle is disposed at the lower part of the throat. The throat is communicated with the through-flow channel inside the flexible drill string through the drainage nozzle. The drainage nozzle is used to jet high-pressure fluid towards the extending direction of the throat, and drive the fluid below the sealing structure to flow above the sealing structure through the fluid jetted by the drainage nozzle, so as to generate a pressure difference between the upper and lower parts of the sealing structure. The pressure difference pushes the drill bit forward; An electric drive actuator, which is electrically connected to the steering mechanism. The electric drive actuator can control the action of the steering mechanism.

2. The rotary steerable drilling tool according to claim 1, wherein The torque transmission string includes a plurality of torque transmission short joints connected in sequence from top to bottom. Adjacent two torque transmission short joints are rotatably connected through an angle-changing force transmission structure. The torque transmission short joint at the lowermost position is connected to the bearing body.

3. The rotary steerable drilling tool according to claim 2, wherein The deflection limit between any torque transmission short joints is more than 2°; 4. The rotary steerable drilling tool according to claim 2, wherein The length of the torque transmission short joint is less than or equal to 5 times the diameter of the bearing body; 5. The rotary steerable drilling tool according to claim 2, wherein The length of the torque transmission short joint is 30% - 300% of the diameter of the bearing body; 6. The rotary steerable drilling tool according to claim 2, wherein The angle-changing force transmission structure includes a universal joint and a sleeve sleeved outside the universal joint. There is a gap between the sleeve and the universal joint to form a deflection space. The universal joint can deflect 0.5° - 15° relative to the axis of the sleeve within the deflection space.

7. The rotary steerable drilling tool according to claim 2, wherein the variable-angle force transmission structure includes a ball seat and a ball head, one of the ball head and the ball seat is provided with a torque transmission groove, the other of the ball head and the ball seat is provided with a torque transmission pin, and the torque transmission pin is rotatably received in the torque transmission groove.

8. The rotary steerable drilling tool according to claim 1, wherein the pressure-bearing hose is a composite material pipe, a rubber pipe or a slotted pipe with a sealing material filled in the slots.

9. The rotary steerable drilling tool according to claim 1, wherein a gauge protection structure is connected to the outside of the load-bearing body, and the gauge protection structure includes scraping blade wings or centralizers.

10. The rotary steerable drilling tool according to claim 1, wherein the guiding mechanism includes at least three accommodation cavities circumferentially spaced on the load-bearing body, a driving piston capable of telescoping in the radial direction of the load-bearing body is arranged in the accommodation cavity, the driving piston can abut against the wellbore wall, and the telescoping of the driving piston can drive the load-bearing body to deflect in a preset direction.

11. The rotary steerable drilling tool according to claim 10, wherein the electric drive actuator includes a motor and a rotary valve, the rotary valve includes a rotary valve disc and a rotary valve seat, the rotary valve seat is fixedly connected to the load-bearing body, the rotary valve seat is provided with a plurality of communication holes respectively corresponding to the accommodation cavities one by one, the rotary valve disc is electrically connected to the motor, and the motor can drive the rotary valve disc to rotate relative to the rotary valve seat.

12. The rotary steerable drilling tool according to claim 1, wherein when reverse circulation drilling is adopted, the propulsion mechanism is a packer ring, the outer diameter of the packer ring is 90% - 110% of the outer diameter of the drill bit, and the packer ring can fit with the inner wall surface of the wellbore or maintain a preset gap.

13. The rotary steerable drilling tool according to any one of claims 1 to 12, wherein the rotary steerable drilling tool further includes a control sub, the control sub is connected between the guiding sub and the flexible drill string, or the control sub is connected at any position in the flexible drill string, or the control sub is connected to the upper end of the flexible drill string, a control circuit is arranged in the control sub, and the control circuit is electrically connected to the electric drive actuator through a jumper line.

14. The rotary steerable drilling tool according to claim 13, wherein the rotary steerable drilling tool further includes a downhole power supply, the downhole power supply is connected to the upper end of the flexible drill string, and the downhole power supply is electrically connected to the control circuit.

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