Micro flexible drilling robot and well completion method for radial horizontal well

Abstract

This invention relates to a micro-flexible drilling robot and a method for creating radial horizontal wells, and pertains to the field of drilling engineering. A first tubular cavity extending forward and backward from a first flexible hose supplies drilling fluid. A turbine traction mechanism is connected at one end to one end of the first flexible hose, and has an inlet at the other end. A first drive channel connects the first tubular cavity and the inlet. The turbine traction mechanism rotates to generate axial thrust when the drilling fluid flows through the first drive channel. A drill bit mechanism is connected at one end to the other end of the first flexible hose, and the other end is a drill head with an outlet. A second drive channel connects the first tubular cavity and the outlet. The drill bit mechanism rotates to break rocks and remove cuttings when the drilling fluid flows through the second drive channel. A controllable deformable skeleton fitted with the first flexible hose is fixed to the turbine traction mechanism and the drill bit mechanism. A control unit drives the controllable deformable skeleton to bend up and down or left and right to deflect the drill bit mechanism and adjust the drilling direction. This solves the problem of difficulty in simultaneously controlling drilling and steering in small-diameter / confined well environments.

Description

Technical Field

[0001] This invention relates to the field of drilling engineering technology, and in particular to a miniature flexible drilling robot and a method for completing radial horizontal wells. Background Technology

[0002] Radial horizontal well technology can drill one or more horizontal holes radially distributed in one or more layers within a vertical wellbore, forming a multi-layered and multi-branched radial oil and gas migration "highway network" in the reservoir. It has broad application prospects in fields such as tapping the potential of old oil fields, unconventional reservoir stimulation and geothermal resource development.

[0003] Currently, the commonly used method for radial horizontal well completion involves achieving ultra-short radius steering within the casing and relying on pure hydraulic rock breaking during drilling. However, because the high-pressure hose cannot transmit axial force, and under high-pressure operating conditions, the steering mechanism exerts significant resistance on the high-pressure hose, making advancement difficult and limiting the extension capacity of radial horizontal wells, and making wellbore trajectory uncontrollable. Furthermore, the low efficiency of pure hydraulic rock breaking in hard formations further restricts the widespread application of this technology in deep oil and gas and geothermal resource development. Summary of the Invention

[0004] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a miniature flexible drilling robot and a method for completing radial horizontal wells, which has the advantages of compact structure, fluid drive, and precise orientation, overcoming the problem in the prior art that it is difficult to simultaneously achieve drilling and steering control in small-diameter / confined well environments.

[0005] A first aspect of the present invention provides a miniature flexible drilling robot, comprising: The first hose has a first lumen extending in the front-back direction for supplying drilling fluid flow; A turbine traction mechanism, one end of which is connected to one end of the first hose, and the other end is provided with a fluid inlet. The turbine traction mechanism is provided with a first drive flow channel communicating with the first pipe cavity and the fluid inlet. The turbine traction mechanism is configured to rotate when the drilling fluid flows through the first drive flow channel to generate axial thrust in the well. The drill bit mechanism has one end connected to the other end of the first hose and the other end being a drill head. The drill head is provided with at least one fluid outlet. The drill bit mechanism is provided with a second drive flow channel communicating with the first tube cavity and at least one of the fluid outlets. The drill bit mechanism is configured to rotate through the drill head when the drilling fluid flows through the second drive flow channel in order to break rocks and remove cuttings in the well. The steering mechanism includes a controllable deformable frame and a control unit. The controllable deformable frame is sleeved on the first flexible hose. Both ends of the controllable deformable frame are fixedly connected to the turbine traction mechanism and the drill bit mechanism, respectively. The control unit is configured to drive the controllable deformable frame to bend in the up-down or left-right direction under electronic control, so as to deflect the drill bit mechanism and adjust the drilling direction of the drill bit mechanism.

[0006] The miniature flexible drilling robot according to a first aspect of the present invention has at least the following beneficial effects: by injecting drilling fluid into the miniature flexible drilling robot, the drilling fluid enters the first drive channel of the turbine traction mechanism through the inlet, enabling the turbine traction mechanism to convert the energy of the drilling fluid into its own rotational kinetic energy, thereby converting the rotational motion of the turbine traction mechanism into axial propulsion in the well, realizing the self-driven stable drilling function of the miniature flexible drilling robot in small diameter / confined well environments; the drilling fluid flowing out from the first drive channel flows through the first hose into the second drive channel of the drill bit mechanism, and then flows out from the drill bit outlet... The fluid flows out of the wellhead and into the downhole annulus, enabling the drill bit mechanism to convert the energy of the drilling fluid into the rotational kinetic energy of the drill bit. This allows the drill bit mechanism to perform mechanical cutting in the well while maintaining localized stable erosion or lubrication, improving drilling efficiency in hard formations and achieving continuous and efficient rock breaking. During drilling, the electrically controlled steering mechanism can be operated, allowing the control unit to control the controllable deformable skeleton to bend vertically or horizontally, creating a deflection force difference. This changes the contact force distribution between the drill bit mechanism and the well wall, completing the deflection in the predetermined direction. This allows for real-time adjustment of the drilling direction, realizing the precise steering control function of the micro flexible drilling robot.

[0007] In some embodiments of the present invention, the turbine traction mechanism includes a rotating drum, a spindle, at least one turbine rotor and at least one turbine stator. The outer peripheral surface of the rotating drum is provided with a plurality of helical flanges. The rotating drum is sleeved on the spindle and is rotatably connected to and sealed with the spindle. The rotating drum and the spindle together form the first drive flow channel. At least one turbine rotor and at least one turbine stator are arranged along the axial direction of the mandrel and disposed in the first drive channel. At least one turbine rotor is fixedly connected to the rotating drum, and at least one turbine stator is sleeved and fixed on the mandrel. The mandrel has a first channel and a second channel at both ends, which are connected to the first drive flow channel. One end of the first channel has the liquid inlet. One end of the mandrel is connected to one end of the first hose so that the second channel is connected to the first cavity.

[0008] In some embodiments of the present invention, the turbine traction mechanism is an eccentric rotating structure.

[0009] In some embodiments of the present invention, the drill bit mechanism includes a first housing, a drive turbine, and a cutting drill bit. The first housing forms a second drive flow channel, the drive turbine is disposed within the second drive flow channel, one end of the cutting drill bit is coaxially connected to the drive turbine and rotatably connected to and sealed with the first housing, and the other end of the cutting drill bit is the drill head and located outside the second drive flow channel. The drive turbine is configured to drive the cutting drill bit to rotate when drilling fluid flows through the second drive flow channel. The cutting drill bit is provided with a flow channel structure, which is connected to the second drive flow channel and at least one of the liquid outlets respectively. The first housing is connected to the other end of the first hose so that the second drive flow channel is connected to the first cavity.

[0010] In some embodiments of the present invention, the drill bit mechanism further includes a flow guide bushing and a septum. The first housing is provided with a first cavity and at least one fluid guiding channel. The flow guide bushing and the septum are disposed in the first cavity to divide the first cavity into a first sub-cavity, a second sub-cavity, and a third sub-cavity arranged sequentially in the front-back direction. The flow guide bushing is provided with at least one flow guide hole. The third sub-cavity, at least one fluid guiding channel, the first sub-cavity, at least one flow guide hole, and the second sub-cavity are sequentially connected to form the second drive flow channel. The drive turbine is located in the first sub-cavity and is configured to rotate when the drilling fluid flows into the first sub-cavity from the fluid guide channel due to the impact of the drilling fluid.

[0011] In some embodiments of the present invention, the first housing is provided with a plurality of injection outlets, the plurality of injection outlets are arranged circumferentially spaced along the first housing and communicate with the second drive flow channel, and the injection outlets are open toward the turbine traction mechanism in the front-rear direction; And / or, the outer circumferential surface of the first housing is provided with at least one flow guide box, the flow guide box is provided with the fluid guiding channel, the inlet of the fluid guiding channel is connected to the third sub-cavity, the outlet of the fluid guiding channel is connected to the first sub-cavity, and is tangent to the circumferential direction of the first sub-cavity or forms an acute angle with the tangent of the circumferential direction of the first sub-cavity, so that the drilling fluid can impact the blades of the drive turbine when it flows out from the outlet of the fluid guiding channel, thereby driving the drive turbine to rotate; And / or, the outer circumferential surface of the first housing is provided with a plurality of first centering parts so that the first housing is centered in the well; And / or, the drill bit has a concave surface on the side away from the turbine traction mechanism in the front-rear direction, and at least one of the liquid outlets is located on the concave surface.

[0012] In some embodiments of the present invention, the controllable deformable skeleton includes two connecting rings, multiple inner rotating rings, multiple outer rotating rings, and at least three controllable deformable units. The multiple inner rotating rings and multiple outer rotating rings are arranged at intervals along the front-back direction and are coaxially alternately arranged. The outer rotating ring is uniformly provided with four connecting arms along its circumference. Two of the connecting arms are arranged radially opposite to each other along the outer rotating ring and are hinged to one of the two adjacent inner rotating rings. The other two connecting arms are arranged radially opposite to each other along the outer rotating ring and are hinged to the other of the two adjacent inner rotating rings. The foremost inner rotating ring is connected to the drill bit mechanism through a corresponding connecting ring, and the rearmost inner rotating ring is connected to the turbine traction mechanism through a corresponding connecting ring. At least three of the controllable deformation units are fixedly connected at both ends to the foremost inner rotating ring and the last inner rotating ring, respectively. The at least three controllable deformation units are evenly arranged along the circumference of the inner rotating ring and slide in contact with the remaining inner rotating ring and all the outer rotating rings. The control unit is configured to control the corresponding controllable deformable unit to extend or shorten in the front-to-back direction, so that the controllable deformable skeleton bends in the up-down or left-to-right direction, thereby causing the drill bit mechanism to deflect. The first hose passes through all the connecting rings, all the inner rotating rings and all the outer rotating rings, and is connected to the turbine traction mechanism and the drill bit mechanism respectively.

[0013] In some embodiments of the present invention, the control unit includes a housing, a controller, a battery, and multiple three-way valves. The housing has an inner cavity, multiple liquid inlet channels, multiple liquid outlet channels, and multiple pressure relief channels. The controller, the battery, and the multiple three-way valves are disposed in the inner cavity. The controller is electrically connected to the battery and the multiple three-way valves respectively. The multiple three-way valves, the multiple liquid inlet channels, the multiple liquid outlet channels, the multiple pressure relief channels, and at least three controllable deformable units are arranged in a one-to-one correspondence. The three valve ports of the three-way valves are respectively connected to the liquid inlet channel, the liquid outlet channel, and the pressure relief channel. The controllable deformation unit is an expansion tube, which forms an expansion channel. The outer shell is located on the inner circumference of the inner rotating ring and is fixedly connected to one of the inner rotating rings and all the expansion tubes, so that the liquid outlet channel is connected to the corresponding expansion channel. The first hose is provided with multiple delivery channels communicating with the first cavity. The multiple delivery channels are arranged one-to-one with the multiple liquid inlet channels. The first hose is inserted and fixed to the outer shell so that the delivery channels are connected with the corresponding liquid inlet channels. The controller is configured to control the opening and closing of the corresponding three-way valve so that one of the liquid inlet channel and the pressure relief channel is connected with the liquid outlet channel, thereby realizing the steering mechanism driving the drill bit mechanism to deflect.

[0014] In some embodiments of the present invention, the control unit includes a housing, a controller, a battery, and a plurality of annular hollow motors. The housing has an inner cavity and a plurality of wire-threading channels. The controller, the battery, and the plurality of annular hollow motors are disposed in the inner cavity. The controller is electrically connected to the battery and the plurality of annular hollow motors respectively. The plurality of wire-threading channels are configured to correspond one-to-one with at least three controllable deformation units. The controllable deformation unit is a pull wire. The remaining inner rotating rings and all the outer rotating rings are provided with through holes for the pull wire to pass through. The outer shell is fixed on the inner circumferential surface of one of the inner rotating rings. The pull wire passes through the corresponding wire-passing channel and is wound around the rotating end of the corresponding annular hollow motor. The controller is configured to control the operation of the corresponding annular hollow motor to release or retract the pull wire, thereby realizing the steering mechanism driving the drill bit mechanism to deflect. The first flexible tube passes through the outer shell and the plurality of annular hollow motors.

[0015] In some embodiments of the present invention, the micro flexible drilling robot further includes a guidance decision mechanism and a second hose. The guidance decision mechanism includes a second housing and an internally connected power supply, a sensing and measurement unit, an intelligent decision unit, and a wireless communication unit. The second housing is provided with a second cavity, and the internally connected power supply, sensing and measurement unit, intelligent decision unit, and wireless communication unit are disposed within the second cavity. The sensing and measurement unit is configured to measure downhole working conditions and physical parameters in real time. The wireless communication unit is configured to wirelessly transmit the real-time measurement data of the sensing and measurement unit and wirelessly receive external commands. The intelligent decision-making unit is wirelessly connected to the steering mechanism. The intelligent decision-making unit is configured to control the operation of the steering mechanism according to the real-time measurement data of the sensing and measurement unit or external commands, so as to adjust the drilling direction of the drill bit mechanism. The second hose has a second cavity extending in the front-back direction for supplying drilling fluid flow. One end of the second hose is inserted and fixed to the second housing and connected to the turbine traction mechanism so that the second cavity communicates with the fluid inlet.

[0016] In some embodiments of the present invention, the outer circumferential surface of the second housing is provided with a plurality of second centering portions so that the second housing is centered in the well.

[0017] A second aspect of the present invention provides a method for forming a radial horizontal well, applied to a miniature flexible drilling robot as described in the first aspect embodiment, the method comprising the following steps: S1: Place the miniature flexible drilling robot inside the well; S2: Drilling fluid is supplied to the miniature flexible drilling robot so that the drilling fluid drives the turbine traction mechanism and the drill bit mechanism to operate; S3: Determine whether the drilling direction needs to be adjusted based on downhole conditions, physical parameters, and external commands; S4: If so, control the steering mechanism to operate and switch from cruise mode to deflection mode to adjust the drilling direction of the drill bit mechanism; S5: After adjusting the drilling direction, control the steering mechanism to operate and switch from the deflection state to the cruise state so that the drill bit mechanism maintains a straight drilling state; S6: Repeat S3 to S5 until the drill bit mechanism reaches the target position or the drilling operation is completed.

[0018] The radial horizontal well formation method according to the second aspect of the present invention has at least the following beneficial effects: after the micro flexible drilling robot is placed in the well, drilling fluid is continuously supplied to the micro flexible drilling robot, so that the drilling fluid can flow sequentially through the inlet, the first drive channel of the turbine traction mechanism, the first hose, the second drive channel of the drill bit mechanism, and the outlet, and then enter the downhole annulus. During the flow of drilling fluid, the energy of the drilling fluid is converted into the rotational kinetic energy of the turbine traction mechanism and the rotational kinetic energy of the drill bit, ensuring that the turbine traction mechanism converts the rotational motion into axial propulsion in the radial horizontal well, realizing the self-driven stable drilling of the micro flexible drilling robot in a small diameter / confined well environment, while ensuring that the drill bit mechanism applies mechanical cutting action in the radial horizontal well and maintains local stable erosion or lubrication, improving the drilling efficiency of the micro flexible drilling robot in hard formations, and realizing continuous and efficient rock breaking.

[0019] During drilling, based on downhole conditions, physical parameters, and external commands, it is determined whether the drilling direction of the micro flexible drilling robot needs to be adjusted. If so, the steering mechanism switches from cruising to deflection mode, causing the steering mechanism to generate a deflection force difference, changing the contact force distribution between the drill bit and the well wall, and completing the deflection in the predetermined direction. This allows for real-time adjustment of the drilling direction, realizing the precise steering control function of the micro flexible drilling robot. After the drilling direction adjustment is completed, the steering mechanism switches from deflection mode to cruising mode, causing the deflection force difference to disappear, and causing the micro flexible drilling robot to return to straight-line propulsion. Before the drill bit reaches the target position or before completing the drilling operation, if the drilling direction needs to be adjusted, the steering mechanism works to realize real-time adjustment of the drilling direction and directional extension of the radial horizontal well section.

[0020] In some embodiments of the present invention, the well-forming method further includes the following steps: S7: During the process of adjusting the drilling direction, the deflection angle of the drill bit mechanism is corrected in real time according to the preset trajectory or target guidance information.

[0021] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description, claims, and drawings. Attached Figure Description

[0022] Figure 1 This is a schematic diagram illustrating the operation of the miniature flexible drilling robot provided in this embodiment of the invention when used in conjunction with general drilling equipment. Figure 2 This is a three-dimensional schematic diagram of a miniature flexible drilling robot provided according to an embodiment of the present invention; Figure 3 This is a cross-sectional schematic diagram of a miniature flexible drilling robot provided according to an embodiment of the present invention; Figure 4 This is a three-dimensional schematic diagram of a drill bit mechanism provided according to an embodiment of the present invention; Figure 5 This is a cross-sectional schematic diagram of a drill bit mechanism provided according to an embodiment of the present invention; Figure 6 This is a partial exploded view of the drill bit mechanism provided according to an embodiment of the present invention; Figure 7 This is a perspective view of a steering mechanism provided according to an embodiment of the present invention; Figure 8 This is a cross-sectional schematic diagram of a steering mechanism provided according to an embodiment of the present invention; Figure 9This is a perspective view of a steering mechanism provided according to another embodiment of the present invention; Figure 10 This is a cross-sectional schematic diagram of a steering mechanism provided according to another embodiment of the present invention; Figure 11 This is a perspective view of a turbine traction mechanism provided according to an embodiment of the present invention; Figure 12 This is an exploded view of a turbine traction mechanism provided according to an embodiment of the present invention; Figure 13 This is a three-dimensional schematic diagram of a guidance decision-making mechanism provided according to an embodiment of the present invention; Figure 14 This is a schematic flowchart of a radial horizontal well construction method provided by an embodiment of the present invention; Figure 15 This is a supplementary flowchart illustrating the well completion method for a radial horizontal well provided according to an embodiment of the present invention.

[0023] Reference numerals: 1. Coiled tubing truck; 2. Control cabinet; 3. Power skid; 4. Drum; 5. Surface controller; 6. Injection head; 7. Blowout preventer; 8. Coiled tubing; 9. Steering mechanism; 10. Hydraulic anchor; 11. Miniature flexible drilling robot; 100. Drill bit mechanism; 110. Cutting drill bit; 111. Central flow channel; 112. Liquid outlet; 113. Concave surface; 114. Groove; 120. Drive turbine; 130. First housing; 131. First connecting pipe; 132. Flow guide box; 133. Front cover; 134. Sleeve; 135. Rear cover; 140. Partition; 150. First straightening part; 161. First sub-cavity; 162. Second sub-cavity; 163. Third sub-cavity; 164. Flow guide outlet; 170. Flow guide bushing; 171. Flow guide hole; 180. Ball bearing; 190. Jet outlet; 200. Steering mechanism; 210. First connecting ring; 220. Inner rotating ring; 230. Outer rotating ring; 240. Second connecting ring; 250. Controllable deformation unit; 251. Expansion tube; 252. Expansion channel; 253. Pull cable; 260. Control unit; 261. Housing; 262. Battery; 263. Three-way valve; 264. Pressure relief channel; 265. Liquid outlet channel; 266. Controller; 267. Annular hollow motor; 300. Turbine traction mechanism; 310. First end cover; 320. Rotary drum; 330. Second end cover; 331. Second connecting pipe; 340. Helical flange; 350. Mandrel; 351. Third connecting pipe; 360. Turbine rotor; 370. Turbine stator; 381. First channel; 382. Second channel; 410. First hose; 411. Delivery channel; 420. Second hose; 500, Guiding decision-making mechanism; 510, Second housing; 511, Sealing housing; 512, Sealing cover; 520, Built-in power supply; 530, Intelligent decision-making unit; 540, Sensing and measurement unit; 550, Second straightening part; 560, Mounting through hole. Detailed Implementation

[0024] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0025] In the description of this invention, it should be understood that features specified as "first" or "second" may explicitly or implicitly include one or more of those features. In the description of this invention, unless otherwise stated, "several" means one or more, and "multiple" means two or more.

[0026] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] The following is for reference. Figures 1 to 15 This invention describes a miniature flexible drilling robot and a method for completing radial horizontal wells, provided by embodiments of the present invention.

[0028] like Figures 1 to 13 As shown, the miniature flexible drilling robot 11 according to the first aspect of the present invention can be applied to the field of oil and gas and geothermal drilling engineering technology. It belongs to the category of downhole miniature self-driven drilling devices and can complete the well completion work of radial horizontal wells. It can perform continuous drilling and directional control in small-diameter or confined wells. The miniature flexible drilling robot 11 of this embodiment has the advantages of compact structure, fluid drive, and precise orientation, overcoming the problem in the prior art that drilling and steering control are difficult to achieve simultaneously in small-diameter / confined well environments.

[0029] The miniature flexible drilling robot 11 has a first direction, and the length direction of the miniature flexible drilling robot 11 extends along the first direction. In this embodiment, it is assumed that the first direction is the front-to-back direction.

[0030] like Figures 1 to 13As shown, the miniature flexible drilling robot 11 includes a first hose 410, a turbine traction mechanism 300, a steering mechanism 200, and a drill bit mechanism 100.

[0031] The first hose 410 extends along the longitudinal direction and has a first cavity. The first cavity extends through the longitudinal direction and can be used to supply drilling fluid flow.

[0032] The turbine traction mechanism 300 extends longitudinally along the front-to-back direction. One end of the turbine traction mechanism 300 is connected to one end of the first hose 410, for example, by inserting the first hose 410 into one end of the turbine traction mechanism 300 to achieve a detachable connection. The other end of the turbine traction mechanism 300 is provided with a fluid inlet. The turbine traction mechanism 300 is provided with a first drive channel, which is connected to both the first cavity and the fluid inlet. The fluid inlet can be connected to a drilling fluid delivery pipe so that drilling fluid flows into the first drive channel of the turbine traction mechanism 300 through the fluid inlet and then flows into the first cavity. The turbine traction mechanism 300 is configured to rotate when the drilling fluid flows through the first drive channel, so that the turbine traction mechanism 300 can generate axial thrust within the well.

[0033] Specifically, such as Figure 2 , Figure 3 , Figure 11 and Figure 12 As shown, the turbine traction mechanism 300 includes a rotating drum 320, a spindle, at least one turbine rotor 360, and at least one turbine stator 370. The outer circumferential surface of the rotating drum 320 is provided with multiple helical flanges 340, which are integrally formed with the rotating drum 320. The multiple helical flanges 340 are spaced apart around the outer circumferential surface of the rotating drum 320 and spaced apart along the axial direction of the rotating drum 320. The rotating drum 320 is sleeved on the spindle and coaxially arranged, and the rotating drum 320 and the spindle are rotatably connected. The contact points between the rotating drum 320 and the spindle are sealed, enabling the rotating drum 320 and the spindle to jointly form a first drive flow channel.

[0034] At least one turbine rotor 360 is arranged axially along the mandrel and disposed within the first drive flow channel. The turbine rotor 360 is fixedly connected to the rotating drum 320, causing the turbine rotor 360 to drive the rotating drum 320 to rotate together. At least one turbine stator 370 is arranged axially along the mandrel and disposed within the first drive flow channel, and is sleeved and fixed on the mandrel. The mandrel has a first channel 381 and a second channel 382 at both ends, both of which are connected to the first drive flow channel. One end of the first channel 381 has a liquid inlet, and one end of the mandrel is connected to one end of the first hose 410, so that the second channel 382 is connected to the first cavity of the first hose 410.

[0035] In this embodiment, the mandrel includes a first end cap 310, a mandrel portion 350, and a second end cap 330. The mandrel portion 350 extends in the front-rear direction. The rotating cylinder 320 is sleeved on the mandrel portion 350 and is coaxially arranged with the mandrel portion 350. The first end cap 310 is coaxially sleeved on one end of the mandrel portion 350 and is detachably connected to the mandrel portion 350. The first end cap 310 is rotatably connected to one end of the rotating cylinder 320 and covers one end opening of the rotating cylinder 320. The second end cap 330 is coaxially sleeved on the other end of the mandrel portion 350 and is integrally formed with the mandrel portion 350. The second end cap 330 is rotatably connected to the other end of the rotating cylinder 320 and covers the other end opening of the rotating cylinder 320.

[0036] A second connecting pipe 331 is formed at one end of the mandrel portion 350. The second connecting pipe 331 can be connected to one end of the drilling fluid delivery pipe. The second connecting pipe 331 is integrally formed with the mandrel portion 350. A first channel 381 is provided at one end of the mandrel portion 350. One end of the first channel 381 is a fluid inlet, and the other end is provided with four circumferentially distributed diversion ports. A third connecting pipe 351 is formed at the other end of the mandrel portion 350. The third connecting pipe 351 can be connected to one end of the first hose 410. The third connecting pipe 351 is integrally formed with the mandrel portion 350. A second channel 382 is provided at the other end of the mandrel portion 350. One end of the second channel 382 is provided with four circumferentially distributed confluence ports, and the other end of the second channel 382 is a drilling fluid outlet. After the drilling fluid flows into the first channel 381 through the inlet, it flows through four branch outlets to the first drive channel, then through four confluence outlets into the second channel 382, ​​and finally through the drilling fluid outlet into the first cavity of the first hose 410. The second connecting pipe 331 and the third connecting pipe 351 are both coaxially arranged with the mandrel part 350.

[0037] There are three turbine rotors 360 and two turbine stators 370. The turbine rotors 360 and turbine stators 370 are arranged alternately in the front-to-back direction. Adjacent turbine rotors 360 and turbine stators 370 can be connected by mutual fitting and rotation.

[0038] When the inlet of the turbine traction mechanism 300 receives drilling fluid, the drilling fluid in the first channel 381 flows into the first drive channel through four branch ports. The drilling fluid flowing along the first drive channel flows to the turbine stator 370 and the turbine rotor 360, driving the turbine rotor 120 to rotate. This causes the turbine rotor 360 to drive the rotating drum 320 to rotate as well. The fluid then flows into the second channel 382 through four return ports, thus collecting and flowing into the first cavity of the first hose 410. The mandrel and the turbine stator 370 are tightly fitted together and remain relatively stationary, without rotation. The turbine rotor 360 and the rotating drum 320 are tightly fitted together and can rotate together. When the spiral flange 340 on the outer periphery of the rotating drum 320 contacts the well wall, the rotational motion of the rotating drum 320 can be converted into a propulsive displacement (i.e., linear motion) along the well shaft axis, enabling the micro-flexible drilling robot 11 to advance in the well.

[0039] It is understandable that the turbine rotor 360 and turbine stator 370 can use straight or curved blades in their blade shape design, and the number of stages (i.e., quantity) of the turbine rotor 360 and turbine stator 370 can be adapted according to the actual disclosure. The overall material of the rotating drum 320 can be metal, alloy, non-metal, or a welded body with metal as the base material and non-metal. The spiral flanges 340 on the outer side of the rotating drum 320 can be arranged in an equal row or spiral arrangement. The spiral flanges 340 can be coated with wear-resistant material, or the spiral flanges 340 can be locally reinforced, or the spiral flanges 340 can be inlaid with wear-resistant material. The contact point between the rotating drum 320 and the spindle is equipped with a labyrinth seal and adopts a wear-resistant design. The shape of the labyrinth seal includes, but is not limited to, straight, zigzag, stepped, or honeycomb. The wear-resistant design includes, but is not limited to, adding lubricating medium, setting wear-resistant material, adding bearings, or placing ball bearings.

[0040] In some examples, the turbine traction mechanism 300 is a concentric rotating structure, with the turbine rotor 360, turbine stator 370, rotating drum 320, and mandrel arranged concentrically. In other examples, the turbine traction mechanism 300 is an eccentric rotating structure, with the centers of the turbine rotor 360 and turbine stator 370 eccentrically positioned relative to the center of the mandrel. This design increases the contact force between the rotating drum 320 and the wellbore, which helps to overcome the problem of slippage caused by the enlargement of the wellbore size during drilling.

[0041] The drill bit mechanism 100 extends longitudinally along the front-to-back direction. One end of the drill bit mechanism 100 is connected to the other end of the first flexible hose 410, for example, by inserting the first flexible hose 410 into one end of the drill bit mechanism 100 for a detachable connection. The other end of the drill bit mechanism 100 is the drill head, which has at least one fluid outlet 112. The drill bit mechanism 100 has a second drive channel, which is connected to the first cavity and at least one fluid outlet 112. The fluid outlet 112 allows drilling fluid to exit the second drive channel and enter the downhole annulus. The drill bit mechanism 100 is configured to rotate as the drilling fluid flows through the second drive channel, enabling the drill head to break rocks and remove cuttings inside the well.

[0042] Specifically, such as Figures 2 to 6 As shown, the drill bit mechanism 100 includes a first housing 130, a drive turbine 120, and a cutting drill bit 110. The first housing 130 forms a second drive flow channel, and the drive turbine 120 is disposed within the second drive flow channel. One end of the cutting drill bit 110 is coaxially connected to the drive turbine 120, thus fixing the drive turbine 120 to the cutting drill bit 110. One end of the cutting drill bit 110 can be mounted on the first housing 130 via a ball bearing 180, enabling a rotatable connection between the cutting drill bit 110 and the first housing 130. The cutting drill bit 110 and the first housing 130 are sealed together. The other end of the cutting drill bit 110 is the drill head, located outside the second drive flow channel and away from the first flexible hose 410. The cutting drill bit 110 has a flow channel structure that connects the second drive flow channel and at least one outlet 112. The first housing 130 is connected to the other end of the first flexible hose 410, allowing the second drive flow channel to communicate with the first tubular cavity. The drive turbine 120 and the cutting drill bit 110 extend in the front-to-back direction along their axes. The drive turbine 120 can convert the kinetic energy of the drilling fluid into the rotational energy of the cutting drill bit 110. The drive turbine 120 is configured to be impacted and propelled by the drilling fluid as it flows through the second drive channel, thereby driving the cutting drill bit 110 to rotate as well, so that the cutting drill bit 110 can perform rock-breaking function.

[0043] More specifically, the drill bit mechanism 100 also includes a flow guide bushing 170 and a septum 140. The first housing 130 is hollow inside, forming a first cavity and at least one fluid guiding channel. The flow guide bushing 170 and the septum 140 are arranged at intervals in the front-back direction and are disposed in the first cavity to divide the first cavity into a first sub-cavity 161, a second sub-cavity 162 and a third sub-cavity 163. The first sub-cavity 161, the second sub-cavity 162 and the third sub-cavity 163 are arranged sequentially in the front-back direction. The first sub-cavity 161 is disposed near the cutting drill bit 110 and the third sub-cavity 163 is disposed near the first flexible tube 410. The flow guide bushing 170 is provided with at least one flow guide hole 171, which is connected to the first sub-cavity 161 and the second sub-cavity 162 respectively. The fluid guide channel is connected to the first sub-cavity 161 and the third sub-cavity 163 respectively. Thus, the third sub-cavity 163, at least one fluid guide channel, the first sub-cavity 161, at least one flow guide hole 171 and the second sub-cavity 162 are sequentially connected and together form the second drive flow channel. The drive turbine 120 is located in the first sub-cavity 161. The drive turbine 120 is configured to rotate when the drilling fluid flows into the first sub-cavity 161 from the fluid guide channel, driven by the impact of the drilling fluid, thereby driving the cutting drill bit 110 to rotate.

[0044] In one specific embodiment, the outer circumferential surface of the first housing 130 is provided with at least one flow guide box 132. The flow guide box 132 is provided with a fluid guiding channel. The inlet of the fluid guiding channel is connected to the third sub-cavity 163, and the outlet of the fluid guiding channel is connected to the first sub-cavity 161. The fluid guiding channel is tangent to the circumferential direction of the first sub-cavity 161 or forms an acute angle with the tangent to the circumferential direction of the first sub-cavity 161, so that the drilling fluid can impact the blades of the drive turbine 120 when it flows out from the outlet of the fluid guiding channel, thereby driving the drive turbine 120 to rotate.

[0045] In this embodiment, the first housing 130 includes a front cover 133, a sleeve 134, and a rear cover 135. The front cover 133 and the rear cover 135 are located on the front and rear sides of the sleeve 134, respectively, and are connected to the sleeve 134 to form a first cavity. The flow guide bushing 170 and the shroud 140 are installed in the first cavity and are fixedly connected to the sleeve 134. The flow guide bushing 170 is provided with a plurality of flow guide holes 171. The flow guide holes 171 are arc-shaped when viewed from the front and rear direction. The plurality of flow guide holes 171 are evenly distributed along the circumference of the flow guide bushing 170 so that the drilling fluid in the first sub-cavity 161 flows to the second sub-cavity 162 through the flow guide holes 171. The flow guide bushing 170 has a central through hole, which can play a role in centering and fixing the cutting drill bit 110 and the ball bearing 180. The front cover 133 has a shaft hole into which one end of the cutting drill bit 110 extends. One end of the rear cover 135 has a first connecting pipe 131. The first connecting pipe 131 can be connected to the first flexible hose 410. The first connecting pipe 131 is integrally formed with the rear cover 135. The cavity of the first connecting pipe 131 is connected to the third sub-cavity 163.

[0046] The outer circumferential surface of the sleeve 134 is provided with two flow guide boxes 132. The two flow guide boxes 132 are evenly arranged along the circumference of the sleeve 134. The flow guide boxes 132 are L-shaped and form liquid guiding channels. The outer circumferential surface of the sleeve 134 is provided with two flow guide inlets and two flow guide outlets 164. The two flow guide inlets are connected to the third sub-cavity 163, and the two flow guide outlets 164 are connected to the first sub-cavity 161. The two flow guide inlets, two flow guide outlets 164 and two liquid guiding channels are arranged in a one-to-one correspondence. One end of the liquid guiding channel is connected to the third sub-cavity 163 through the flow guide inlet, and the other end of the liquid guiding channel is connected to the first sub-cavity 161 through the flow guide outlet 164.

[0047] The guide outlet 164 serves as the outlet of the fluid guiding channel. It is tangentially arranged to the circumference of the first sub-cavity 161, or forms a certain acute angle with the tangent of the circumference of the first sub-cavity 161. This ensures that the drilling fluid in the fluid guiding channel can impact the blades of the drive turbine 120 when it flows into the first sub-cavity 161, causing a portion of the drilling fluid energy to be converted into the rotational kinetic energy of the drive turbine 120. This enables the drive turbine 120 to drive the cutting drill bit 110 to rotate as the drilling fluid flows through the second drive channel.

[0048] The drill bit is provided with three fluid outlets 112, which are evenly arranged around the circumference of the cutting drill bit 110. The flow channel structure of the cutting drill bit 110 includes a central flow channel 111 and three jet flow channels. The central flow channel 111 extends in the front-to-back direction and is coaxially arranged with the cutting drill bit 110. The three jet flow channels and the three fluid outlets 112 are arranged in a one-to-one correspondence, and the jet flow channels are respectively connected to the central flow channel 111 and the fluid outlets 112. The drilling fluid in the second sub-cavity 162 flows into the central flow channel 111, and flows through the multiple jet flow channels to the fluid outlets 112, and finally flows out of the drill bit mechanism 100 and enters the downhole annulus.

[0049] It is understood that the blade form of the drive turbine 120 includes, but is not limited to, single-channel bucket blades, double-channel bucket blades, or straight blades. The cutting drill bit 110 can be a milling cutter or a grinding tool, and can be made of materials such as impregnated diamond, metal, or alloy, and can use cemented carbide components such as titanium carbide, tungsten carbide, or diamond. Specifically, the diamond-impregnated cutting drill bit 110 mainly relies on the high-stress contact between a large number of micro-scale diamond particles and the rock to achieve rock breaking during drilling. Its rock breaking methods are mainly micro-cutting, micro-grinding, and micro-crack-induced fracturing. The diamonds exposed on the matrix surface produce a grinding effect on the rock under high rotation speed and low drilling pressure, causing the rock to be peeled off in the form of fine rock chips. At the same time, the continuous abrasion of the metal matrix during drilling promotes the continuous exposure of new diamond particles, while dulled or broken particles gradually fall off, thus forming a self-sharpening cycle mechanism of "matrix abrasion - diamond renewal", ensuring that the cutting drill bit 110 can achieve stable and continuous rock breaking in high-hardness and high-abrasive formations. The cutting drill bit 110 can be connected to the drive turbine 120 and the first housing 130 via a clamping tool to facilitate the replacement of worn cutting drill bit 110.

[0050] Furthermore, such as Figure 4 and Figure 6 As shown, the outer circumferential surface of the first housing 130 is provided with a plurality of first centering portions 150. The first centering portions 150 enable the first housing 130 to be centered within the well, thereby giving the first housing 130 the characteristic of centering and stabilizing. It can be understood that the first centering portions 150 can be rigid structures, elastic structures, rollers, or ball bearings, etc. In this embodiment, the first centering portions 150 are cuboid in shape and are fixedly connected to the outer circumferential surface of the sleeve 134, and the plurality of first centering portions 150 are arranged at intervals along the circumference of the sleeve 134.

[0051] Furthermore, such as Figure 4 and Figure 5 As shown, the drill bit has a concave surface 113 on the side away from the turbine traction mechanism 300 along the front-rear direction, and at least one fluid outlet 112 is provided on the concave surface 113. This design allows drilling fluid to be smoothly discharged from the fluid outlet 112 when the drill bit is breaking rocks and removing cuttings. In addition, the outer circumferential surface of the drill bit has multiple grooves 114. The grooves 114 are arc-shaped when viewed along the front-rear direction, and the grooves 114 extend along the front-rear direction and penetrate through the front and rear sides of the drill bit.

[0052] The steering mechanism 200 extends along the longitudinal direction. The steering mechanism 200 includes a controllable deformable frame and a control unit 260. The controllable deformable frame is sleeved on the first flexible hose 410. The two ends of the controllable deformable frame are fixedly connected to the turbine traction mechanism 300 and the drill bit mechanism 100, respectively. The control unit 260 is configured to drive the controllable deformable frame to bend in the vertical or horizontal direction under electronic control, so as to deflect the drill bit mechanism 100 and thereby adjust the drilling direction of the drill bit mechanism 100.

[0053] Specifically, such as Figure 2 , Figure 3 , Figures 7 to 10 As shown, the controllable deformable skeleton includes two connecting rings, multiple inner rotating rings 220, multiple outer rotating rings 230, and at least three controllable deformable units 250. Both the inner rotating rings 220 and the outer rotating rings 230 are annular, with the outer diameter of the inner rotating ring 220 being smaller than that of the outer rotating ring 230. The inner rotating rings 220 and the outer rotating rings 230 are arranged at intervals along the front-to-back direction, coaxially, and alternately. That is, there is one outer rotating ring 230 between any two adjacent inner rotating rings 220. The number of inner rotating rings 220 is one more than the number of outer rotating rings 230.

[0054] The outer rotating ring 230 has four connecting arms, which are integrally formed with the outer rotating ring 230. The four connecting arms are evenly arranged along the circumference of the outer rotating ring 230, with two connecting arms located on the front side of the outer rotating ring 230 and the other two connecting arms located on the rear side of the outer rotating ring 230. Two of the connecting arms are arranged radially opposite each other along the outer rotating ring 230 and are hinged to one of the two adjacent inner rotating rings 220 via a hinge shaft. The other two connecting arms are arranged radially opposite each other along the outer rotating ring 230 and are hinged to the other of the two adjacent inner rotating rings 220 via a hinge shaft. Therefore, the four hinge points on each inner rotating ring 220 are evenly arranged along the circumference of the inner rotating ring 220. By connecting multiple inner rotating rings 220 and multiple outer rotating rings 230 in series, they can jointly form a bending deformation skeleton, which can bend in the vertical or horizontal direction. It is understood that the number of inner rotating rings 220 and outer rotating rings 230 can be selected according to actual needs and is not limited here.

[0055] Two connecting rings are respectively located on the front and rear sides of the controllable deformable frame. The foremost inner rotating ring 220 is connected to the drill bit mechanism 100 via a corresponding connecting ring, and the rearmost inner rotating ring 220 is connected to the turbine traction mechanism 300 via a corresponding connecting ring. The connecting rings, inner rotating ring 220, and outer rotating ring 230 are coaxially arranged. The connecting rings, inner rotating ring 220, and outer rotating ring 230 are detachably connected to each other, facilitating modular replacement and maintenance. All three rings are made of wear-resistant materials to improve their service life.

[0056] In this embodiment, the two connecting rings are respectively configured as a first connecting ring 210 and a second connecting ring 240. Both the first and second connecting rings are cylindrical. The first connecting ring 210 is located on the front side of the controllable deformable frame. The front end of the first connecting ring 210 is fixedly connected to the rear cover 135 of the drill bit mechanism 100 by screws. The rear end of the first connecting ring 210 has two first connecting parts, which are arranged radially opposite to each other and hinged to the foremost inner rotating ring 220. The second connecting ring 240 is located on the rear side of the controllable deformable frame. The rear end of the second connecting ring 240 is fixedly connected to the first housing 130 of the turbine traction mechanism 300 by screws. The front end of the second connecting ring 240 has two second connecting parts, which are arranged radially opposite to each other and hinged to the rearmost inner rotating ring 220. The four hinge points on each inner rotating ring 220 are evenly distributed circumferentially around the inner rotating ring 220. Of course, it is possible that the first connecting ring 210 is fixedly connected to the foremost inner rotating ring 220, and the second connecting ring 240 is fixedly connected to the rearmost inner rotating ring 220.

[0057] The controllable deformation unit 250 extends along the front-to-back direction. At least three controllable deformation units 250 are fixedly connected at both ends to the foremost inner rotating ring 220 and the rearmost inner rotating ring 220, respectively. The at least three controllable deformation units 250 are evenly arranged along the circumference of the inner rotating rings 220. Furthermore, the outer circumferential surfaces of the at least three controllable deformation units 250 are in sliding contact with the remaining inner rotating rings 220 and all outer rotating rings 230, respectively, so that the at least three controllable deformation units 250 and the bending deformation skeleton together constitute a controllable deformation skeleton. The number of controllable deformation units 250 can be three, four, or more. The material of the controllable deformation unit 250 can be metal, alloy, or non-metal such as rubber.

[0058] The control unit 260 is configured to control the corresponding controllable deformation unit 250 to extend or shorten in the front-to-back direction, so that the controllable deformation skeleton bends in the up-down or left-to-right direction, thereby causing the drill mechanism 100 to deflect. This enables the steering mechanism 200 to deflect at a small angle by selectively controlling the deformation action of the controllable deformation unit 250.

[0059] The first flexible hose 410 passes through all the connecting rings, all the inner rotating rings 220, and all the outer rotating rings 230, and is connected to the turbine traction mechanism 300 and the drill bit mechanism 100 respectively. In this embodiment, the first flexible hose 410, the connecting rings, the inner rotating rings 220, and the outer rotating rings 230 are arranged coaxially.

[0060] In Example 1, as Figure 7 and Figure 8 As shown, the control unit 260 includes a housing 261, a controller 266, a battery 262, and multiple three-way valves 263. The housing 261 has an inner cavity, multiple inlet channels, multiple outlet channels 265, and multiple pressure relief channels 264. The controller 266, battery 262, and multiple three-way valves 263 are located within the inner cavity. The controller 266 is electrically connected to the battery 262 and the multiple three-way valves 263. The battery 262 can be a toroidal battery, providing power to the controller 266. The controller 266 can be a control board, integrating a central processing unit, a general-purpose processor, a digital signal processor, and application-specific integrated circuits. The controller 266 can control the opening and closing of the three-way valves 263. Multiple three-way valves 263, multiple inlet channels, multiple outlet channels 265, multiple pressure relief channels 264, and at least three controllable deformation units 250 are arranged in a one-to-one correspondence. The three valve ports of the three-way valves 263 are respectively connected to the inlet channel, the outlet channel 265, and the pressure relief channel 264.

[0061] The controllable deformation unit 250 is an expansion tube 251, which is evenly arranged along the circumference of the inner rotating ring 220. The expansion tube 251 forms an expansion channel 252, which extends in the front-back direction. The outer shell 261 is disposed on the inner circumference of the inner rotating ring 220 and is fixedly connected to one of the inner rotating rings 220 and all the expansion tubes 251, so that each liquid outlet channel 265 communicates with the corresponding expansion channel 252.

[0062] In this embodiment, four expansion tubes 251 are provided, and are respectively arranged opposite to the four hinge points of the inner rotating ring 220. The front ends of the four expansion tubes 251 are fixedly connected to the rear side of the foremost inner rotating ring 220, and the rear ends of the four expansion tubes 251 are fixedly connected to the front side of the rearmost inner rotating ring 220. The expansion tubes 251 are steel hoses. Furthermore, each expansion tube 251 adopts a split design with two parts, the front and rear parts of which are respectively fixedly connected to the front and rear sides of the outer shell 261. The liquid outlet channel 265 of the outer shell 261 is T-shaped and can communicate with the expansion channels 252 on the front and rear sides. The outer shell 261 is fixedly connected to the middle inner rotating ring 220. Of course, it is possible that each expansion tube 251 is an integral design and located on the periphery of the outer shell 261. In this case, the liquid outlet channel 265 is in a straight line and is connected to the expansion channel 252; the outer shell 261 is fixedly connected to the inner rotating ring 220 at the front or the inner rotating ring 220 at the back.

[0063] The first hose 410 is provided with multiple delivery channels 411, which communicate with the first cavity. The delivery channels 411 extend radially along the first hose 410, and each delivery channel 411 corresponds to a different inlet channel. The first hose 410 passes through and is fixed to the housing 261, so that each delivery channel 411 communicates with its corresponding inlet channel. The housing 261 may be annular to allow the first hose 410 to pass through. The contact between the first hose 410 and the housing 261 is sealed. The controller 266 is configured to control the opening and closing of a corresponding three-way valve 263, so that one of the inlet channel and the pressure relief channel 264 communicates with the outlet channel 265, thereby enabling the steering mechanism 200 to drive the drill bit mechanism 100 to deflect.

[0064] Understandably, during the flow of drilling fluid along the first hose 410, the controller 266 can control the corresponding three-way valve 263 to switch according to the control signal to pressurize the expansion tube 251. The opening of the three-way valve 263 ensures that the corresponding inlet and outlet channels 265 are connected. At this time, the pressure relief channel 264 and the outlet channel 265 are not connected. The drilling fluid in the first tube cavity can flow into the expansion channel 252 through the inlet and outlet channels 265. Due to the pressure difference between the inside and outside, the expansion... The tube 251 can extend radially or axially and generate contact force with the inner rotating ring 220 and the outer rotating ring 230. However, drilling fluid does not flow into the expansion channels 252 of the remaining expansion tubes 251, and the length of the expansion tubes 251 remains unchanged. Therefore, by controlling the length changes of multiple expansion tubes 251, the expansion tubes 251 can drive the controllable deformable skeleton to bend and deform through the force, thereby causing the steering mechanism 200 to switch to the deflection state, so as to adjust the drilling direction of the drill bit mechanism 100.

[0065] When a reset is required, the controller 266 controls the corresponding three-way valve 263 to switch to depressurize the expansion tube 251. The closure of the three-way valve 263 ensures that the corresponding fluid outlet channel 265 and the pressure relief channel 264 are connected. At this time, the fluid inlet channel and the fluid outlet channel 265 are not connected to each other. The drilling fluid in the first hose 410 cannot flow into the fluid outlet channel 265. The drilling fluid in the expansion channel 252 is discharged outward to the downhole annulus through the fluid outlet channel 265 and the pressure relief channel 264, so that the expansion tube 251 returns to its original length, that is, the expansion tube 251 retracts to its initial shape, thereby prompting the steering mechanism 200 to switch to the cruise state, so that the drill bit mechanism 100 returns to the straight-line propulsion state.

[0066] In Example 2, as Figure 9 and Figure 10 As shown, the control unit 260 includes a housing 261, a controller 266, a battery 262, and multiple annular hollow motors 267. The housing 261 has an inner cavity and multiple wiring channels. The controller 266, battery 262, and multiple annular hollow motors 267 are located within the inner cavity. The controller 266 is electrically connected to the battery 262 and the multiple annular hollow motors 267. The battery 262 can be a toroidal battery, providing power to the controller 266. The controller 266 can be a control board, integrating a central processing unit, a general-purpose processor, a digital signal processor, and application-specific integrated circuits. The controller 266 can control the opening, closing, and rotation switching of the annular hollow motors 267. The annular hollow motors 267 can be ultrasonic motors. The multiple wiring channels are arranged in a one-to-one correspondence with at least three controllable deformable units 250.

[0067] The controllable deformation unit 250 is a pull wire 253, which is evenly distributed along the circumference of the inner rotating ring 220 and extends in the front-to-back direction. The remaining inner rotating rings 220 and all the outer rotating rings 230 have through holes for the pull wire 253 to pass through, allowing the pull wire 253 to slide in contact with the remaining inner rotating rings 220 and all the outer rotating rings 230. The front and rear ends of the pull wire 253 are fixedly connected to the foremost and rearmost inner rotating rings 220, respectively. The outer casing 261 is fixedly disposed on the inner circumferential surface of one of the inner rotating rings 220. The pull wire 253 passes through the corresponding through-path and is wound around the rotating end (i.e., the rotating shaft or rotating platform) of the corresponding annular hollow motor 267. The controller 266 is configured to control the operation of the corresponding annular hollow motor 267 to release or retract the pull wire 253, thereby enabling the steering mechanism 200 to drive the drill bit mechanism 100 to deflect. The rotating end of the annular hollow motor 267 can be wound with one pull wire 253 or two pull wires 253. The first flexible tube 410 passes through the outer shell 261 and multiple annular hollow motors 267, and the first flexible tube 410, the outer shell 261 and the annular hollow motors 267 are arranged coaxially.

[0068] In this embodiment, four pull wires 253 are provided and are evenly distributed along the circumference of the inner rotating ring 220 at the four hinge points. The pull wires 253 can be steel wire ropes. The outer shell 261 is fixedly connected to the middle inner rotating ring 220. There are two annular hollow motors 267, and each annular hollow motor 267 has two pull wires 253 wound around its rotating end. The two pull wires 253 are wound in opposite directions and are arranged opposite each other along the radial direction of the inner rotating ring 220.

[0069] Therefore, the controller 266 can control the operation of the corresponding annular hollow motor 267 according to the control signal. When the annular hollow motor 267 rotates forward, the rotating end of the annular hollow motor 267 will release one of the pull wires 253 and retract the other pull wire 253. At this time, one of the pull wires 253 gradually extends from the corresponding wire channel to increase its length, while the other pull wire 253 gradually retracts from the corresponding wire channel to decrease its length. When the length of the pull wire 253 decreases, a tension is generated between the foremost inner rotating ring 220 and the last inner rotating ring 220. By controlling the length changes of multiple pull wires 253, the pull wires 253 can drive the controllable deformable frame to bend and deform through the tension, thereby causing the steering mechanism 200 to switch from the cruise state to the deflection state to adjust the drilling direction of the drill bit mechanism 100.

[0070] When a reset is required, the annular hollow motor 267 reverses under the control command of the controller 266. The rotating end of the annular hollow motor 267 retracts one of the pull wires 253 and releases the other pull wire 253, causing the lengths of both pull wires 253 to return to their original lengths. This causes the steering mechanism 200 to switch from the deflection state to the cruising state, so that the drill bit mechanism 100 returns to the straight-line propulsion state. Of course, it is possible that the outer casing 261 is fixedly connected to either the foremost inner rotating ring 220 or the rearmost inner rotating ring 220.

[0071] In the use of the micro-flexible drilling robot 11 provided in the first aspect embodiment of the present invention, drilling fluid is injected into the micro-flexible drilling robot 11, allowing the drilling fluid to enter the first drive channel of the turbine traction mechanism 300 through the inlet. This enables the turbine traction mechanism 300 to convert the energy of the drilling fluid into its own rotational kinetic energy, allowing the turbine traction mechanism 300 to convert rotational motion into axial propulsion within the well, thereby realizing the self-driven stable drilling function of the micro-flexible drilling robot 11 in small-diameter / confined well environments. The drilling fluid flowing out from the first drive channel flows into the drill bit mechanism 100 through the first hose 410. Within the second drive channel, the fluid flows out from the outlet 112 of the drill bit and enters the downhole annulus, enabling the drill bit mechanism 100 to convert the energy of the drilling fluid into the rotational kinetic energy of the drill bit. This allows the drill bit mechanism 100 to perform mechanical cutting in the well while maintaining localized stable erosion or lubrication, improving drilling efficiency in hard formations and achieving continuous and efficient rock breaking. During drilling, a deflection force difference can be generated through the electrically controlled steering mechanism 200 to change the contact force distribution between the drill bit mechanism 100 and the well wall, completing the deflection in the predetermined direction. This allows for real-time adjustment of the drilling direction, realizing the precise steering control function of the micro flexible drilling robot 11.

[0072] In some embodiments, such as Figure 6 As shown, the first housing 130 is provided with multiple injection outlets 190, which are spaced apart circumferentially along the first housing 130. These injection outlets 190 communicate with the second drive channel and are open towards the turbine traction mechanism 300 in the front-rear direction. In this embodiment, the rear side of the rear cover 135 is provided with multiple injection outlets 190, which are evenly arranged circumferentially along the rear cover 135 and communicate with the third sub-cavity 163. Furthermore, the rear side of the guide box 132 is also provided with injection outlets 190, which communicate with the fluid guiding channel. This design allows the first housing 130 to divert drilling fluid, ensuring that the drilling fluid flowing into the second drive channel of the drill bit mechanism 100 flows out not only from the outlet 112 but also from the injection outlets 190. High-pressure drilling fluid is ejected from the injection outlets 190, and the reaction force of the ejected fluid provides forward propulsion to the micro-flexible drilling robot 11.

[0073] In some embodiments, such as Figure 2 , Figure 3 and Figure 13As shown, the miniature flexible drilling robot 11 also includes a guidance decision-making mechanism 500 and a second flexible hose 420. The guidance decision-making mechanism 500 includes a second housing 510, a built-in power supply 520, a sensing and measurement unit 540, an intelligent decision-making unit 530, and a wireless communication unit. The second housing 510 has a second cavity, within which the built-in power supply 520, sensing and measurement unit 540, intelligent decision-making unit 530, and wireless communication unit are located. In this embodiment, the second housing 510 includes a sealing shell 511 and a sealing cover 512, which are connected and together form the second cavity. The second housing 510 may be cylindrical.

[0074] The built-in power supply 520, sensing and measurement unit 540, intelligent decision-making unit 530, and wireless communication unit are electrically connected to each other. The built-in power supply 520 can be a toroidal battery, which provides electrical energy. The sensing and measurement unit 540 is configured to measure downhole working conditions and physical parameters in real time. The wireless communication unit is configured to wirelessly transmit the real-time measurement data of the sensing and measurement unit 540 and wirelessly receive external commands. The intelligent decision-making unit 530 is wirelessly connected to the steering mechanism 200 and is configured to control the operation of the steering mechanism 200 according to the real-time measurement data of the sensing and measurement unit 540 or external commands to adjust the drilling direction of the drill bit mechanism 100. In addition, the controller 266 of the steering mechanism 200 may be equipped with a wireless receiver, which is wirelessly connected to the wireless communication unit.

[0075] Understandably, the wireless communication unit can be integrated into the intelligent decision-making unit 530. The wireless communication unit can transmit downhole measurement data to the surface controller 5 in real time or periodically, and can also receive instructions from the surface controller 5, thereby enabling information interaction with the surface controller 5. The intelligent decision-making unit 530 can be a control board, integrating a central processing unit, a general-purpose processor, a digital signal processor, and application-specific integrated circuits, and storing a large artificial intelligence model, capable of autonomous learning and decision-making. The sensing and measurement unit 540 includes multiple measurement and control sensors, including but not limited to temperature, pressure, lithology, and hydrology sensors. The sensing and measurement unit 540 can collect various types of data, such as azimuth, dip, acceleration, magnetometer data, and well logging data, and can transmit this data to the intelligent decision-making unit 530 for real-time data processing and control strategy generation. This allows for automatic closed-loop control of the steering mechanism 200 according to a preset trajectory, and also enables the wireless communication unit to send data to the surface controller 5 and receive correction instructions from the surface controller 5.

[0076] The second hose 420 has a second cavity extending through it in a front-to-back direction. The second cavity is used to supply drilling fluid. One end of the second hose 420 passes through and is fixed to the second housing 510. For example, the second housing 510 has a mounting through hole 560 for the second hose 420 to pass through. One end of the second hose 420 is fixedly connected to the turbine traction mechanism 300 so that the second cavity communicates with the fluid inlet. The other end of the second hose 420 can be connected to the drilling fluid delivery pipe. The second hose 420 can be the same as the first hose 410 in size and material.

[0077] Understandably, the guidance decision-making mechanism 500 can monitor downhole geology and drilling trajectory information in real time, and can wirelessly communicate with the ground controller 5 and the controller 266 of the steering mechanism 200. Multiple guidance decision-making mechanisms 500 are connected in series, provided the steering spacing is met. The integrated functions of these multiple series-connected guidance decision-making mechanisms 500 include, but are not limited to, information acquisition, trajectory mapping, and data transmission. In the structure of the micro-flexible drilling robot 11, the steering mechanism 200, the turbine traction mechanism 300, and the guidance decision-making mechanism 500 can be connected in multiple stages, either intermittently or directly. The various mechanisms can be connected by standardized connectors via threaded or snap-fit ​​connections, facilitating the replacement of the drill bit mechanism 100 or damaged parts.

[0078] Furthermore, such as Figure 13 As shown, the outer circumferential surface of the second housing 510 is provided with a plurality of second centering portions 550. The second centering portions 550 enable the second housing 510 to be centered within the well, thereby giving the second housing 510 the characteristic of centering and alignment. It can be understood that the second centering portions 550 can be rigid structures, elastic structures, rollers, or ball bearings, etc. In this embodiment, the second centering portions 550 are cuboid in shape and are fixedly connected to the outer circumferential surface of the sealing shell 511, and the plurality of second centering portions 550 are evenly arranged along the circumference of the sealing shell 511.

[0079] Understandably, the overall outer diameter of the micro flexible drilling robot 11 can be 35mm to 45mm. The steering mechanism 200, the turbine traction mechanism 300 and the guidance decision mechanism 500 can have different maximum outer diameters, and their maximum outer diameters are less than or equal to the maximum outer diameter of the cutting drill bit 110.

[0080] In the micro-flexible drilling robot 11 of the first aspect of the present invention, the turbine traction mechanism 300 receives drilling fluid and uses the energy of the drilling fluid to linearly drive the multi-stage turbine rotor 360 to rotate the drum 320. Simultaneously, when the spiral flange 340 outside the drum 320 contacts the well wall, the rotational motion of the drum 320 is converted into axial propulsion. Therefore, it can adapt to self-driven propulsion in small wellbores without the need for additional drilling pressure and torque. The turbine 120 is directly driven by the drilling fluid, eliminating the need for external high torque transmission or external pressurization equipment. The short length of each mechanism makes it easier to traverse confined spaces. The drill bit mechanism 100 uses a portion of the drilling fluid energy to drive the rotation of the cutting drill bit 110, and with the design of the jet outlet 190, it maintains localized stable erosion or lubrication while ensuring mechanical cutting, significantly improving drilling efficiency in hard formations and achieving continuous and efficient rock breaking in small-diameter well environments. The steering mechanism 200 works in conjunction with the guidance decision-making mechanism 500 to deflect the drill bit mechanism 100 without large-scale deformation during propulsion, reducing the impact on propulsion efficiency, improving fault isolation capability, and enhancing reliability.

[0081] The miniature flexible drilling robot 11 can perform real-time closed-loop control and downhole orientation. The guidance decision-making mechanism 500 integrates a sensing and measurement unit 540, an intelligent decision-making unit 530, and a wireless communication unit, which can realize real-time monitoring and closed-loop control of downhole attitude. It supports two working modes: remote command from the ground and local autonomous control, and is suitable for precise orientation in complex well environments.

[0082] The miniature flexible drilling robot 11 is modular and easy to maintain. The modular design facilitates the rapid replacement of worn parts on the ground and adapts to different diameter rotary drums 320 and controllable deformable skeletons, improving on-site deployment efficiency and reducing the cost of secondary well entry.

[0083] The micro flexible drilling robot 11 has a simple and reliable overall structure, modular integration, and short length of each mechanism. It relies on drilling fluid for propulsion and simple and reliable steering, making it suitable for small-diameter or confined well environments and easy for old well retrofitting and on-site deployment.

[0084] like Figures 1 to 14 As shown, the radial horizontal well formation method according to a second aspect embodiment of the present invention, applied to a micro-flexible drilling robot 11 as described in the first aspect embodiment, includes the following steps: Step S1: Place the miniature flexible drilling robot 11 into the well.

[0085] Step S2: Drilling fluid is delivered to the micro flexible drilling robot 11 so that the drilling fluid drives the turbine traction mechanism 300 and the drill bit mechanism 100 to operate.

[0086] Step S3: Determine whether the drilling direction needs to be adjusted based on the downhole conditions, physical parameters, and external commands.

[0087] Step S4: If yes, control the steering mechanism 200 to operate and switch from cruise mode to deflection mode to adjust the drilling direction of the drill bit mechanism 100.

[0088] Step S5: After adjusting the drilling direction, control the steering mechanism 200 to operate and switch from the deflection state to the cruise state so that the drill bit mechanism 100 maintains a straight drilling state.

[0089] Step S6: Repeat steps S3 to S5 until the drill bit mechanism 100 reaches the target position or the drilling operation is completed.

[0090] Understandably, drilling fluid can be water pressurized to 20MPa to 80MPa or supercritical carbon dioxide, among other fluids. When supercritical carbon dioxide is used as the drilling fluid, the formation temperature gradually increases with depth, with a temperature gradient of approximately 20-50℃ / km. At depths of several hundred meters, the temperature exceeds the critical temperature of carbon dioxide (31.1℃), reaching a supercritical state near the cutting bit 110. After being ejected through the injection outlet 190, the pressure of the supercritical carbon dioxide fluid drops sharply. Under the Joule-Thomson effect, the temperature of the supercritical carbon dioxide fluid decreases dramatically, providing a cooling effect on the cutting bit 110 and the downhole drilling. As the drilling fluid circulates, carbon dioxide gradually rises in the annulus, its temperature constantly changing with the formation temperature, its pressure constantly changing with well depth, and its density constantly changing with temperature and pressure.

[0091] like Figure 1 As shown, the power skid 3 of the coiled tubing trolley 1 operates, enabling the drum 4 to rotate and release the coiled tubing 8. The coiled tubing 8 extends downhole via the injection head 6 and blowout preventer 7, and is then turned 90° by the steering mechanism 9 before docking with the miniature flexible drilling robot 11. The miniature flexible drilling robot 11 continuously delivers drilling fluid. The hydraulic anchor 10 is used to anchor the downhole tubing string, preventing axial movement or bending during high-pressure drilling and ensuring drilling operation safety.

[0092] After the micro flexible drilling robot 11 is installed in the well, drilling fluid is continuously injected into the micro flexible drilling robot 11 through the coiled tubing 8, so that the drilling fluid can flow sequentially through the inlet, the first drive channel of the turbine traction mechanism 300, the first hose 410, the second drive channel of the drill bit mechanism 100 and the outlet 112, and then enter the downhole annulus.

[0093] During the drilling fluid flow process, the energy of the drilling fluid is converted into the rotational kinetic energy of the turbine traction mechanism 300 and the drill bit. This ensures that the turbine traction mechanism 300 converts rotational motion into axial propulsion in the radial horizontal well, enabling the micro flexible drilling robot 11 to perform self-driven stable drilling in a small diameter / confined well environment. At the same time, it ensures that the drill bit mechanism 100 applies mechanical cutting action in the radial horizontal well and maintains local stable erosion or lubrication. Furthermore, drilling fluid is injected through the injection outlet 190 to form a certain propulsion force to assist the micro flexible drilling robot 11 in advancing, thereby improving the drilling efficiency of the micro flexible drilling robot 11 in hard formations and achieving continuous and efficient rock breaking.

[0094] During drilling, based on the downhole working conditions and physical parameters (attitude / geological data collected by the sensing and measurement unit 540) and the instructions from the ground controller 5 at the control cabinet 2, it is determined whether the drilling direction of the micro flexible drilling robot 11 needs to be adjusted. If turning is required, the turning mechanism 200 is activated, causing the turning mechanism 200 to switch from the cruising state to the deflection state, so that the turning mechanism 200 can generate a certain deflection force difference, change the contact force distribution between the drill bit mechanism 100 and the well wall, and complete the deflection in the predetermined direction. Thus, the drilling direction can be adjusted in real time, realizing the precise steering control function of the micro flexible drilling robot 11.

[0095] After the drilling direction adjustment is completed, the steering mechanism 200 switches from the deflection state to the cruise state, which makes the deflection force difference disappear and causes the micro flexible drilling robot 11 to resume the straight-line propulsion state. Before the drill bit mechanism 100 drills to the target position or completes the drilling operation, when it is necessary to adjust the drilling direction, the steering mechanism 200 works to realize the real-time adjustment of the drilling direction and the directional extension of the radial horizontal well section.

[0096] In some embodiments, such as Figure 15 As shown, the well completion method for radial horizontal wells also includes the following steps: Step S7: During the process of adjusting the drilling direction, the deflection angle of the drill bit mechanism 100 is corrected in real time according to the preset trajectory or target guidance information.

[0097] The guidance decision-making mechanism 500 controls the steering mechanism 200 through closed-loop feedback to achieve precise control of the deflection angle, which can be corrected in real time according to the preset trajectory or target guidance situation.

[0098] The ground controller 5 can receive drilling data from the miniature flexible drilling robot 11, including but not limited to mapping data and fault data; determine the fault type of the drilling equipment based on the drilling data; determine the corresponding ground operation command based on the fault type, and send the ground operation command to the downhole drilling tools; wherein, the ground operation command is used to correct the working parameters. The ground controller 5 can determine the fault type of the drilling equipment based on the drilling data, and determine the corresponding operation command to adjust the normal operation of the equipment. For example, when the difference between the well trajectory and the preset track exceeds the preset error, an adjustment operation command is issued to adjust the drilling direction of the miniature flexible drilling robot 11.

[0099] The radial horizontal well construction method of this embodiment achieves radial horizontal well construction within a confined downhole space through a self-propelled drilling method driven by in-well fluid, without the need for external rigid thrust rods, ultra-high pump pressure, and traditional rotary steering systems.

[0100] In the well completion method for radial horizontal wells, the turbine rotor 360 in the traction mechanism of the turbine 120 driven by drilling fluid drives the rotating drum 320 to rotate. Through the contact between the spiral flange 340 on the outer side of the rotating drum 320 and the well wall, the rotational motion is converted into axial propulsion motion, realizing self-driven stable drilling in a small wellbore. During the drilling process, at least three controllable deformation units 250 located at the rear end of the drill bit mechanism 100 and distributed in a circular pattern are selectively controlled to create a deflection force difference in the controllable deformation skeleton, thereby realizing real-time adjustment of the drilling direction and directional extension of the radial horizontal well section. At the same time, combined with downhole measurement and control and directional decision-making, closed-loop control of the well completion process is realized.

[0101] Compared with existing ultra-short radius hydraulic jet drilling and rotary steering technologies, the radial horizontal well drilling method of this embodiment can complete high-precision directional drilling under micro-bore conditions. It has the advantages of weak coupling between propulsion and steering, good well continuity, small system size, and strong engineering adaptability. It is particularly suitable for old well refurbishment and new well development, effectively shortening the drilling cycle, saving drilling costs, reducing the labor intensity of workers, and improving construction results. Therefore, it has good market potential.

[0102] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0103] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A miniature flexible drilling robot, characterized in that, include: The first hose has a first cavity extending in the front-back direction for supplying drilling fluid flow; A turbine traction mechanism, one end of which is connected to one end of the first hose, and the other end is provided with a fluid inlet. The turbine traction mechanism is provided with a first drive flow channel communicating with the first pipe cavity and the fluid inlet. The turbine traction mechanism is configured to rotate when the drilling fluid flows through the first drive flow channel to generate axial thrust in the well. The drill bit mechanism has one end connected to the other end of the first hose and the other end being a drill head. The drill head is provided with at least one fluid outlet. The drill bit mechanism is provided with a second drive flow channel communicating with the first tube cavity and at least one of the fluid outlets. The drill bit mechanism is configured to rotate through the drill head when the drilling fluid flows through the second drive flow channel in order to break rocks and remove cuttings in the well. The steering mechanism includes a controllable deformable frame and a control unit. The controllable deformable frame is sleeved on the first flexible hose. Both ends of the controllable deformable frame are fixedly connected to the turbine traction mechanism and the drill bit mechanism, respectively. The control unit is configured to drive the controllable deformable frame to bend in the up-down or left-right direction under electronic control, so as to deflect the drill bit mechanism and adjust the drilling direction of the drill bit mechanism.

2. The miniature flexible drilling robot according to claim 1, characterized in that, The turbine traction mechanism includes a rotating drum, a spindle, at least one turbine rotor, and at least one turbine stator. The outer circumferential surface of the rotating drum is provided with multiple helical flanges. The rotating drum is sleeved on the spindle and is rotatably connected to and sealed with the spindle. The rotating drum and the spindle together form the first drive flow channel. At least one turbine rotor and at least one turbine stator are arranged along the axial direction of the mandrel and disposed in the first drive channel. At least one turbine rotor is fixedly connected to the rotating drum, and at least one turbine stator is sleeved and fixed on the mandrel. The mandrel has a first channel and a second channel at both ends, which are connected to the first drive flow channel. One end of the first channel has the liquid inlet. One end of the mandrel is connected to one end of the first hose so that the second channel is connected to the first cavity.

3. The miniature flexible drilling robot according to claim 2, characterized in that, The turbine traction mechanism is an eccentric rotating structure.

4. The miniature flexible drilling robot according to claim 1, characterized in that, The drill bit mechanism includes a first housing, a drive turbine, and a cutting drill bit. The first housing forms a second drive flow channel. The drive turbine is disposed within the second drive flow channel. One end of the cutting drill bit is coaxially connected to the drive turbine and rotatably connected to and sealed with the first housing. The other end of the cutting drill bit is the drill head and is located outside the second drive flow channel. The drive turbine is configured to drive the cutting drill bit to rotate when drilling fluid flows through the second drive flow channel. The cutting drill bit is provided with a flow channel structure, which is connected to the second drive flow channel and at least one of the liquid outlets respectively. The first housing is connected to the other end of the first hose so that the second drive flow channel is connected to the first cavity.

5. The miniature flexible drilling robot according to claim 4, characterized in that, The drill bit mechanism further includes a flow guide bushing and a septum. The first housing has a first cavity and at least one fluid guiding channel. The flow guide bushing and the septum are disposed in the first cavity to divide the first cavity into a first sub-cavity, a second sub-cavity, and a third sub-cavity arranged sequentially in the front-back direction. The flow guide bushing has at least one flow guide hole. The third sub-cavity, at least one fluid guiding channel, the first sub-cavity, at least one flow guide hole, and the second sub-cavity are sequentially connected to form the second drive flow channel. The drive turbine is located in the first sub-cavity and is configured to rotate when the drilling fluid flows into the first sub-cavity from the fluid guide channel due to the impact of the drilling fluid.

6. The miniature flexible drilling robot according to claim 5, characterized in that, The first housing is provided with a plurality of injection outlets, which are spaced apart circumferentially along the first housing and communicate with the second drive channel. The injection outlets open toward the turbine traction mechanism in the front-rear direction. And / or, the outer circumferential surface of the first housing is provided with at least one flow guide box, the flow guide box is provided with the fluid guiding channel, the inlet of the fluid guiding channel is connected to the third sub-cavity, the outlet of the fluid guiding channel is connected to the first sub-cavity, and is tangent to the circumferential direction of the first sub-cavity or forms an acute angle with the tangent of the circumferential direction of the first sub-cavity, so that the drilling fluid can impact the blades of the drive turbine when it flows out from the outlet of the fluid guiding channel, thereby driving the drive turbine to rotate; And / or, the outer circumferential surface of the first housing is provided with a plurality of first centering parts so that the first housing is centered in the well; And / or, the drill bit has a concave surface on the side away from the turbine traction mechanism in the front-rear direction, and at least one of the liquid outlets is located on the concave surface.

7. The miniature flexible drilling robot according to claim 1, characterized in that, The controllable deformable skeleton includes two connecting rings, multiple inner rotating rings, multiple outer rotating rings, and at least three controllable deformable units. The multiple inner rotating rings and multiple outer rotating rings are arranged at intervals along the front-back direction and are coaxially alternately arranged. The outer rotating rings are evenly provided with four connecting arms along their circumference. Two of the connecting arms are arranged radially opposite to each other along the outer rotating rings and are hinged to one of the two adjacent inner rotating rings. The other two connecting arms are arranged radially opposite to each other along the outer rotating rings and are hinged to the other of the two adjacent inner rotating rings. The foremost inner rotating ring is connected to the drill bit mechanism through a corresponding connecting ring, and the rearmost inner rotating ring is connected to the turbine traction mechanism through a corresponding connecting ring. At least three of the controllable deformation units are fixedly connected at both ends to the foremost inner rotating ring and the last inner rotating ring, respectively. The at least three controllable deformation units are evenly arranged along the circumference of the inner rotating ring and slide in contact with the remaining inner rotating ring and all the outer rotating rings. The control unit is configured to control the corresponding controllable deformable unit to extend or shorten in the front-to-back direction, so that the controllable deformable skeleton bends in the up-down or left-to-right direction, thereby causing the drill bit mechanism to deflect. The first hose passes through all the connecting rings, all the inner rotating rings and all the outer rotating rings, and is connected to the turbine traction mechanism and the drill bit mechanism respectively.

8. The miniature flexible drilling robot according to claim 7, characterized in that, The control unit includes a housing, a controller, a battery, and multiple three-way valves. The housing has an inner cavity, multiple liquid inlet channels, multiple liquid outlet channels, and multiple pressure relief channels. The controller, the battery, and the multiple three-way valves are located in the inner cavity. The controller is electrically connected to the battery and the multiple three-way valves. The multiple three-way valves, the multiple liquid inlet channels, the multiple liquid outlet channels, the multiple pressure relief channels, and at least three controllable deformation units are arranged in a one-to-one correspondence. The three valve ports of the three-way valves are respectively connected to the liquid inlet channel, the liquid outlet channel, and the pressure relief channel. The controllable deformation unit is an expansion tube, which forms an expansion channel. The outer shell is located on the inner circumference of the inner rotating ring and is fixedly connected to one of the inner rotating rings and all the expansion tubes, so that the liquid outlet channel is connected to the corresponding expansion channel. The first hose is provided with multiple delivery channels communicating with the first cavity. The multiple delivery channels are arranged one-to-one with the multiple liquid inlet channels. The first hose is inserted and fixed to the outer shell so that the delivery channels are connected with the corresponding liquid inlet channels. The controller is configured to control the opening and closing of the corresponding three-way valve so that one of the liquid inlet channel and the pressure relief channel is connected with the liquid outlet channel, thereby realizing the steering mechanism driving the drill bit mechanism to deflect.

9. The miniature flexible drilling robot according to claim 7, characterized in that, The control unit includes a housing, a controller, a battery, and multiple annular hollow motors. The housing has an inner cavity and multiple wiring channels. The controller, the battery, and the multiple annular hollow motors are located in the inner cavity. The controller is electrically connected to the battery and the multiple annular hollow motors respectively. The multiple wiring channels are configured to correspond one-to-one with at least three controllable deformation units. The controllable deformation unit is a pull wire. The remaining inner rotating rings and all the outer rotating rings are provided with through holes for the pull wire to pass through. The outer shell is fixed on the inner circumferential surface of one of the inner rotating rings. The pull wire passes through the corresponding wire-passing channel and is wound around the rotating end of the corresponding annular hollow motor. The controller is configured to control the operation of the corresponding annular hollow motor to release or retract the pull wire, thereby realizing the steering mechanism driving the drill bit mechanism to deflect. The first flexible tube passes through the outer shell and the plurality of annular hollow motors.

10. The miniature flexible drilling robot according to any one of claims 1 to 9, characterized in that, The micro flexible drilling robot also includes a guidance decision-making mechanism and a second hose. The guidance decision-making mechanism includes a second housing and an internally connected power supply, a sensing and measurement unit, an intelligent decision-making unit, and a wireless communication unit. The second housing has a second cavity, and the internally connected power supply, sensing and measurement unit, intelligent decision-making unit, and wireless communication unit are located inside the second cavity. The sensing and measurement unit is configured to measure downhole working conditions and physical parameters in real time. The wireless communication unit is configured to wirelessly transmit the real-time measurement data of the sensing and measurement unit and wirelessly receive external commands. The intelligent decision-making unit is wirelessly connected to the steering mechanism. The intelligent decision-making unit is configured to control the operation of the steering mechanism according to the real-time measurement data of the sensing and measurement unit or external commands, so as to adjust the drilling direction of the drill bit mechanism. The second hose has a second cavity extending in the front-back direction for supplying drilling fluid flow. One end of the second hose is inserted and fixed to the second housing and connected to the turbine traction mechanism so that the second cavity communicates with the fluid inlet.

11. The miniature flexible drilling robot according to claim 10, characterized in that, The outer circumferential surface of the second housing is provided with a plurality of second centering parts to center the second housing within the well.

12. A method for completing a radial horizontal well, characterized in that, Applied to the micro-flexible drilling robot as described in any one of claims 1 to 11, the well completion method includes the following steps: S1: Place the miniature flexible drilling robot inside the well; S2: Drilling fluid is supplied to the miniature flexible drilling robot so that the drilling fluid drives the turbine traction mechanism and the drill bit mechanism to operate; S3: Determine whether the drilling direction needs to be adjusted based on downhole conditions, physical parameters, and external commands; S4: If so, control the steering mechanism to operate and switch from cruise mode to deflection mode to adjust the drilling direction of the drill bit mechanism; S5: After adjusting the drilling direction, control the steering mechanism to operate and switch from the deflection state to the cruise state so that the drill bit mechanism maintains a straight drilling state; S6: Repeat S3 to S5 until the drill bit mechanism reaches the target position or the drilling operation is completed.

13. The method for creating a radial horizontal well according to claim 12, characterized in that, The well-forming method also includes the following steps: S7: During the process of adjusting the drilling direction, the deflection angle of the drill bit mechanism is corrected in real time according to the preset trajectory or target guidance information.

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