WO2020224510A1

WO2020224510A1 - Rotary steering tool and transmission device

Info

Publication number: WO2020224510A1
Application number: PCT/CN2020/087944
Authority: WO
Inventors: 刘庆波; 底青云; 杨永友
Original assignee: 中国科学院地质与地球物理研究所
Priority date: 2019-05-07
Filing date: 2020-04-30
Publication date: 2020-11-12
Also published as: CN110080682A; US20220049553A1; CN110080682B

Abstract

A rotary steering tool, comprising: a power unit (130) having an output shaft capable of outputting torque and a bias driving part capable of outputting a radial force and/or an axial force; a transmission shaft (1202) connected to the output shaft; a support shaft connected to the transmission shaft (1202) by means of a rotating structure, a rotation axis of the rotating structure being perpendicular to an axis of the output shaft, the support shaft having an inner wall defining an accommodating cavity and a forward end and a backward end formed at two ends of the accommodating cavity, the rotation center of the rotating structure being located in the accommodating cavity, and the backward end of the support shaft being capable of being driven by the radial force outputted by the bias driving part; and a drill bit (110) having a drill bit tail end, the drill bit (110) being connected, at the drill bit tail end, to the forward end of the support shaft. The present invention can improve the deflecting capability of a drill tool and reduce the energy consumption for driving the drill tool.

Description

Rotating guide tool and transmission device

Technical field

The invention relates to a rotary steering tool and equipment device, which are used to improve the deflection building capacity of rotary steering drilling equipment, and belong to the field of petroleum drilling.

Background technique

At present, rotary steering drilling technology is a breakthrough and strategically significant technology among various advanced drilling technologies and techniques developed at home and abroad. Since its appearance in the 1990s, it has set off a revolution in directional drilling technology.

Before the advent of rotary steering drilling technology, a sliding steering drilling system driven by a mud motor was used to implement steering drilling. The sliding steering drilling system does not rotate during the steering drilling process, but slides along the axis of the well wall and is guided by sliding. The tool changes the inclination and azimuth of the borehole to control the borehole trajectory. The problems of the sliding steering drilling system include difficulty in sliding, the need to maintain orientation, the cleanliness of the wellbore is poor, and the drilling rate is low, which may cause buckling and self-locking. The existence of these problems affects the progress of drilling and the equipment normal operation.

The rotary steering drilling system keeps the direction of the borehole rotating during the drilling process. Compared with the sliding steering drilling system, it has low friction and torsion resistance, high drilling speed, low cost, short well construction period, and smooth well trajectory. Easy to adjust and extend the length of the horizontal section.

There are two commonly used rotary guidance technologies, one is directional guidance and the other is push-to-support guidance. The Chinese authorized patent CN104619944B obtained by the American company Halliburton discloses a directional steering tool, which provides a modular actuator, a steering tool and a rotary steering drilling system. The modular actuator includes a barrel and is structured as Coupled to the outer periphery of the housing. The accumulator is housed in the cylinder, and the hydraulically actuated actuator is slidably disposed in the cylinder, and moves between an activated position and an inactive position, so that the actuator piston selectively squeezes the slope surface of the drive shaft Thereby changing the direction of the drill string.

The US patent application document US20140209389A1 discloses a rotary guide tool, which includes a non-rotating body and a rotating shaft including a deflectable unit. By controlling the circumferential position of the eccentric sleeve, the deflectable unit is deflected, thereby adjusting the drill bit Drilling direction.

The United States patent application document US20170107762A1 discloses another type of rotary steering technology, namely push-to-lean rotary steering technology, which includes push parts arranged around the drill pipe and a hydraulic drive system for driving these push parts. The system can selectively drive the pushing member to move between the pushing position and the non-pushing position. When in the pushing position, the pushing member can push against the well wall in a flapping manner to generate guiding force and change the direction of the drilling. The push-to-type rotary steering system needs to act on the entire drill tool assembly in the actual operation process, and the rigidity of the drill tool assembly is relatively large, so that the pure push-to-type steering system is limited.

It should be noted that the above content belongs to the technical cognition category of the inventor and does not necessarily constitute the prior art.

Summary of the invention

In order to solve the above problems, the present invention provides a rotary guide tool, which is characterized in that it comprises:

The power unit has an output shaft capable of outputting torque and an offset driving part capable of outputting radial force and/or axial force;

A transmission shaft connected to the output shaft;

A support shaft connected to the transmission shaft through a rotation structure, the rotation axis of the rotation structure is perpendicular to the axis of the output shaft; the support shaft has

The inner wall defining the accommodating cavity and the forward and rearward ends formed at both ends of the accommodating cavity; the center of rotation of the rotating structure is located in the accommodating cavity; the rear end of the supporting shaft can be The radial force driven by the bias drive unit;

A drill bit has a drill bit tail end, and the forward end of the drill bit and the support shaft are connected to the drill bit tail end.

The driving torque of the power unit is transmitted to the drill bit through the above-mentioned rotary guide tool, wherein the support shaft is sleeved outside the transmission shaft, and the transmission shaft and the support shaft partially overlap in the axial direction to connect the transmission shaft and the support shaft. As close as possible to the drill bit, the transmission device connecting the power unit and the drill bit should have as small a curvature radius as possible during skew operation. When driven by a radial load, the radius of curvature will be smaller when the same range of radial movement occurs. , The greater the bending angle, which can improve the efficiency of the well deviation angle and azimuth angle change, so as to improve the deflection ability of the rotary steering tool.

In addition, the support shaft constitutes the external structure of the aforementioned transmission device, and the power unit applies lateral force or radial force to the upper support shaft through the force application structure. Under the action of the axial force or the radial force, the support shaft will generate a rotating structure. The offset of the drive shaft and the combined axis of the drill tool and the support shaft produce an offset angle. At the same time, under the action of the fulcrum, the force of the support shaft will be directly transmitted to the drill bit, and finally the entire rotation The steering tool produces the build rate in the specified direction. As mentioned above, under the driving force applied by the power unit, the force-receiving part is only the support shaft, rather than the entire drill tool assembly (including drill collars and other structures), which can shorten the load caused by dead weight and reaction force. This type of structure can reduce unnecessary energy consumption and reduce the power consumption of the drive system including the power unit.

In addition, the axial nesting of the transmission shaft and the support shaft and the change of the force position of the driving force can also reduce the possibility of self-locking. In the skew operation, the direction of the drilling will be changed as needed. At this time, the three-point fixed circle is used to make the drilling tool bend. When the direction of the drilling changes greatly, the transmission shaft and the support shaft may be stuck in different sections of the drilling and self-locking, which also means, The use of a three-point fixed-circle bending drive method needs to gradually change the inclination angle and azimuth angle, which limits the drilling tool’s deflection ability. In the solution of the present invention, the driving force for changing the direction of the drilling tool is directly applied to the connection with the drill bit. On the support shaft, the three-point circle method is no longer used, and the distance between the rotating node and the drill bit is also shortened, which is mainly beneficial to shorten the length of the support shaft, thereby reducing the possibility of self-locking.

In a preferred embodiment, the rotation structure includes a revolute joint forming a spherical pair with the support shaft; and a flexible member that passes through the revolute joint and is connected to the support shaft.

The implementation of the rotating structure preferably adopts a flexible hinge structure. In order to allow the transmission shaft and the support shaft to rotate relative to each other to form a substantial bend, the spherical pair provides a rotating track, and the flexure deforms to achieve a flexible hinge. The flexure itself also has the function of storing elastic potential energy and gradually driving the rotating structure back straight.

In a preferred embodiment, the revolute joint includes a first protrusion having a first truncated spherical surface close to the forward end of the support shaft, the support shaft has a first groove, and the first groove is connected to the The first protrusion cooperates with the spherical surface of the first section to form a spherical pair.

The spherical pair is formed at least at one end of the transmission shaft close to the forward end of the support shaft. The transmission shaft extends into the accommodating cavity formed by the support shaft. The first groove formed in the accommodating cavity first stops the transmission shaft from approaching the forward end. Movement trend, in addition, it also provides a rotating receiving surface, no matter whether the driving force is axial force or radial force, after pushing the support shaft, it will drive the support shaft to rotate relative to the drive shaft based on the spherical surface pair. The contact surface of the spherical pair here will bear a certain load, and the forming area of the spherical pair will be a truncated spherical surface. The angular range of the truncated spherical surface part will be greater than the maximum allowable rotation angle, which is defined as the transmission shaft and The maximum allowable relative rotation angle of the support shaft.

The spherical pair also plays a supporting role. When the drill bit bears the geological reaction load of the drilling layer, the spherical pair helps to stably support the drive shaft in the support shaft.

In a preferred embodiment, the surface hardness of the first groove is greater than the surface hardness of the first protrusion.

The surface hardness of the first groove is higher than that of the first protrusion, which is represented by a wear-resistant material, for example, a wear-resistant cast iron material or a surface-treated wear-resistant layer is formed on the surface of the first groove. One implementation is to provide a detachable wear sleeve in the accommodating cavity of the support shaft, and the first groove is formed on the wear sleeve. The formation position of the spherical pair will be the position where the load is concentrated, and it is also the wear-prone position. It is set as a detachable structure, which is convenient for maintenance and replacement.

In a preferred embodiment, the rotation structure includes a pair of connecting keys arranged with the central axis of rotation of the transmission shaft as a symmetrical axis, and the pair of connecting keys is installed on the rotating joint; The keyway that the connecting key fits;

The connecting key has a second protrusion, and the surface of the second protrusion is a truncated cylindrical shape with the rotation axis of the rotating structure as the center axis.

In order to reliably transmit torque, the support shaft and the transmission shaft are set as a key connection, and in order to achieve relative rotation, the top of the connecting key is set as a cylindrical surface to support the top of the connecting key without interference with the keyway during rotation.

In a preferred embodiment, the revolute joint further includes a third protrusion formed at an end of the forward end of the connecting key away from the support shaft; the third protrusion has the same shape as the first truncated spherical portion Concentric second truncated spherical surface;

The support shaft has a third groove, and the third groove and the third protrusion cooperate with the second cross-sectional spherical surface to form a spherical pair.

In a more complete rotation structure, a third protrusion opposite to the first protrusion is provided, that is, a third protrusion far from the forward end of the support shaft relative to the first protrusion, and spherical supports are provided at the opposite ends, and the stop transmission While the shaft moves away from the forward end of the support shaft, the revolute joint is jointly limited by the first groove and the third groove, and the revolute joint is stably supported.

In a preferred implementation manner, the third groove is formed in the blocking structure provided in the accommodating cavity installed on the support shaft, which facilitates the non-return member. The transmission shaft extends into the accommodating cavity of the support shaft and approaches the movement tendency of the front end of the support shaft. The internal structure of the supported shaft is stopped, and the movement tendency to escape the support will be stopped by the blocking structure.

In a preferred embodiment, one end of the flexure is mounted on the fixed part of the support shaft, and the other end of the flexure is supported by the support part of the transmission shaft; The center of rotation is located between the fixing part and the supporting part.

The flexure is arranged to pass through the rotation center of the rotating structure, that is, the bending deformation structure and the rotating structure form a positional relationship that partially overlaps, which is also a further optimization way to shorten the overall radius of curvature of the bending structure. In addition, the flexible piece preferably has a flexible sleeve structure, which has a hollow channel and openings at both ends of the channel, passing through the center of rotation, and an opening at one end connected to the support shaft for mud passing through the drill bit to flow in, enter the hollow channel, and then pass through the drive The opening at one end of the shaft flows out into the power unit, and the mud removal at the rear end is consistent with the traditional steering drill method and principle. That is, in this preferred manner, the mud passage through the rotating structure is provided by a flexible sleeve, and the central axis of the flexible sleeve preferably coincides with or nearly coincides with the central axis of the drive shaft.

In a preferred embodiment, it further includes an annular pressure balance portion connecting the inner wall of the support shaft and the outer wall of the transmission shaft, a portion of the inner wall of the support shaft, a portion of the outer wall of the transmission shaft and the pressure balance portion The inner surfaces together define the medium cavity.

As the buffer and lubrication of the rotating structure, a medium cavity is formed between the support shaft and the transmission shaft to flush the lubricating medium, such as hydraulic oil, to lubricate the rotating pair and the spherical pair formed by each contact surface. At the same time, the filled medium can also Play a role in buffering the impact of the load. The pressure balance part is, for example, an elastic sleeve-shaped member. The two ends are respectively connected to the transmission shaft and the support shaft. The sleeve-shaped member and the transmission shaft form a medium extension cavity communicating with the medium cavity. When the transmission shaft and the support shaft rotate relative to each other When the medium in the medium extension cavity is compressed, one side of the sleeve-like member will also be compressed. Both compressions will generate energy accumulation, which will help maintain the overall pressure balance of the rotating structure. A typical sleeve-shaped member is a bellows, and a heat-resistant rubber sleeve similar in shape to the bellows can also be used.

In a preferred embodiment, the shortest distance between the center of rotation and the tail end of the drill bit is not greater than 3.5 times the maximum radial dimension of the support shaft.

As a favorable design, the drill bit support shaft is designed to be shorter, referring to the radial size of the support shaft, shorten the support shaft, especially the size from the rotation center of the support shaft to the drill bit installation position, which is more conducive to the technical solution description of the present invention The advantage of the rotating structure is to reduce the radius of curvature, improve the ability to build angle, and reduce the loss of drilling tools.

At the same time, in the present invention, the transmission device formed by the transmission shaft and the support shaft will also be explained as an independent technical solution for protection. The plan is as follows:

The transmission devices are connected separately:

The power unit has an output shaft capable of outputting torque and an offset driving part capable of outputting radial force;

Drill bit, with the end of the drill bit;

The device includes:

A transmission shaft coaxially connected with the output shaft;

A support shaft coaxially connected with the transmission shaft through a rotating structure, the rotation axis of the rotating structure is perpendicular to the axis of the output shaft; the support shaft has

The accommodating cavity and the forward and rearward ends formed at both ends of the accommodating cavity; the rotation center of the rotating structure is located in the accommodating cavity; the rear end of the supporting shaft can be biased Driven by the radial force output by the driving part; the forward end and the drill bit are coaxially connected to the tail end of the drill bit.

The advantages of the transmission device will be embodied through the use of the aforementioned transmission guide tool, and will not be repeated here.

Description of the drawings

The drawings described here are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention, and do not constitute an improper limitation of the present invention. In the attached picture:

Fig. 1 shows a schematic diagram of the structure of a rotary guide tool in an embodiment of the present invention.

2 is a schematic diagram showing the structural composition of the transmission device in the rotary guide tool in an embodiment of the present invention;

FIG. 3 illustrates a schematic diagram of the structure of the transmission shaft in the rotary guide tool in an embodiment of the present invention.

Detailed ways

In order to explain the overall concept of the present invention more clearly, a detailed description will be given below by way of example in conjunction with the accompanying drawings of the specification.

It should be noted that in the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described here. Therefore, the protection scope of the present invention is not Limitations of the specific embodiments disclosed.

In addition, in the description of the present invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal" "," "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc. indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and other terms should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection , Or integrated; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal communication between two elements or the interaction relationship between two elements. However, the indication of direct connection means that the connected two main bodies do not construct a connection relationship through an excessive structure, but are only connected through a connection structure to form a whole. For those of ordinary skill in the art, the specific meaning of the above-mentioned terms in the present invention can be understood according to specific circumstances.

In the present invention, unless expressly stipulated and defined otherwise, the first feature “on” or “under” the second feature may be in direct contact with the first and second features, or the first and second features may be indirectly through an intermediary. contact. In the description of this specification, descriptions with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean specific features described in conjunction with the embodiment or example , Structure, materials or features are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

As shown in FIG. 1, in an embodiment of the present invention, a structural schematic diagram of a downhole drilling tool assembly is described. The rotary steering tool includes a drill bit 110, a transmission device 120, and a power unit 130, and the components also include rotary steering MWD unit 140 with tool matching.

For each part of the structure, the drill bit 110 is used for drilling, cutting and destroying the rock formation, and plays the role of rock breaking, and is directly connected with the transmission device 120; the power unit assembly 130 provides the driving force for the transmission device 120, and the driving force can be radial or axial. The MWD unit 140 is a conventionally configured monitoring device that can measure and monitor wellbore trajectory parameters and rotary steering tool working devices, and is equipped with a mud pulse generator or electromagnetic wave transmission unit to drive downhole Useful information is transmitted to the ground operating system.

FIG. 2 is a schematic diagram of the structural assembly of the transmission device 120. It mainly includes a transmission shaft and a support shaft, and the transmission shaft extends into the support shaft and is connected by a rotary joint. The rotary joint can transmit torque between the transmission shaft and the support shaft, and the transmission shaft and the support shaft can rotate relatively through the rotary joint . To change the direction of the drill bit, thereby adjusting the well inclination and azimuth.

As shown in the figure, the support shaft includes an upper support shaft 1211 and a lower support shaft 1201. The lower support shaft 1201 is connected to the drill bit. The transmission shaft 1202 and the connecting key 1203 are the main structural components for power transmission. The keyway formed in the lower support shaft 1201 has an accommodating cavity to transmit torque. At the same time, the connecting key also cooperates with the keyway to form a rotating pair. As shown in the figure, the two pairs of connecting keys are connected to the rotating joint of the front section of the drive shaft through a hole column structure. When the lower supporting shaft rotates relative to one of the pair of connecting keys, the central shaft of the other pair of connecting keys having a hole-column connection structure is used as the rotating shaft. The center of the hole-column connection of each connection key meets the rotation center of the revolute joint

The drive shaft 1202 is fixedly connected with the power unit through a threaded structure, so that it can withstand the torque and driving force provided by the power unit.

The tightening member 1204 and the flexible wear-resistant sleeve 1205 are used to seal and isolate the mud passage in the device from the outer annular mud passage. At the same time, the tightening piece is fixedly connected to the lower supporting shaft, which can be regarded as a part of the supporting shaft, that is, one end of the flexible wear-resistant sleeve is fixedly connected to the supporting shaft. The other end of the flexible wear-resistant sleeve is supported on the inner hole of the transmission shaft and sealed by a sealing structure.

There is a spherical substructure between the wear sleeve 1206 and the transmission shaft 1202, thereby forming a universal transmission node. The structure of the spherical pair is shown in the figure, including the front-end spherical pair and the rear-end spherical pair. Specifically, the revolute joint includes a first protrusion having a first truncated spherical surface close to the forward end of the support shaft, the support shaft has a first groove, and the first groove and the first protrusion are matched with the first cross-sectional spherical surface A front end spherical surface pair is formed; the revolute joint also includes a third protrusion formed at one end of the forward end of the connecting key away from the support shaft; the third protrusion has a second truncated spherical surface that is concentric with the first truncated spherical surface; the support shaft has a Three grooves, the third groove and the third protrusion cooperate with the second cross-section spherical surface to form a rear end spherical surface pair.

The anti-dropping part 1207 is mainly used to prevent the transmission device from separating from the drilling tool assembly during the lifting process of the transmission guide tool. Specifically, it is to prevent the transmission shaft from separating from the support shaft.

The revolving joint is immersed in the closed hydraulic oil filled in the medium cavity. The hydraulic oil must be vacuumed before work. The oil circuit system has a sleeve-shaped pressure balance member 1208, and the two ends are connected to the transmission shaft and the support shaft. It is a high temperature resistant rubber part, but also can be a metal bellows or other types of balance structures. It can adaptively balance the external mud pressure to automatically adapt to the underground high temperature and high pressure environment.

The oil filling plugs 1209 and 1212 are used to seal the oil filling ports of the medium cavity containing the hydraulic oil, and the oil filling plugs 1209 and 1212 are removed after the tool is assembled. Then connect the external vacuum oil filling device to complete the oil filling operation. The sealing

members

1213 and 1214 are high-temperature static sealing structures, such as O-rings, which are used to achieve a sealing function.

In the actual work process, the upper support shaft 1211 and the power unit, the power unit acts on the upper support shaft 1211 through a suitable force structure. This force can be a radial force or an axial force, which acts on the outside. Under the action of force, an offset around the rotating structure is generated, so that the center line of the rotary guide tool and the drilling tool assembly axis have an offset angle. At the same time, under the action of the fulcrum, the force on the upper support shaft will pass through the lower support The shaft is directly transmitted to the drill bit part, and finally the entire drill tool assembly generates a ramp rate in the specified direction. Since the force-bearing part is only the transmission device, not the entire drill tool assembly, this type of rotary steering structure reduces unnecessary energy consumption At the same time, the ability to build a pitch will be improved.

The parts of the present invention that are not described in detail belong to the common knowledge of those skilled in the art.

Claims

A rotary guide tool, characterized in that it comprises:

The power unit has an output shaft capable of outputting torque and an offset driving part capable of outputting radial force and/or axial force;

A transmission shaft connected to the output shaft;

A support shaft connected to the transmission shaft through a rotation structure, the rotation axis of the rotation structure is perpendicular to the axis of the output shaft; the support shaft has

The inner wall defining the accommodating cavity and the forward and rearward ends formed at both ends of the accommodating cavity; the center of rotation of the rotating structure is located in the accommodating cavity; the rear end of the supporting shaft can be The radial force driven by the bias drive unit;

A drill bit has a drill bit tail end, and the forward end of the drill bit and the support shaft are connected to the drill bit tail end.
The rotary guide tool according to claim 1, wherein the rotation structure includes a revolute joint forming a spherical pair with the support shaft; and a flexible member that passes through the revolute joint and is connected to the support shaft.
The rotary guide tool according to claim 2, wherein the revolute joint includes a first protrusion having a first truncated spherical surface close to the forward end of the support shaft, and the support shaft has a first groove The first groove and the first protrusion cooperate with the spherical surface of the first section to form a spherical pair.
The rotary guide tool of claim 3, wherein the surface hardness of the first groove is greater than the surface hardness of the first protrusion.
The rotary guide tool according to claim 3, wherein the revolute joint further comprises a pair of connecting keys arranged with the central axis of rotation of the transmission shaft as a symmetrical axis, and the pair of connecting keys are installed on the revolving joint ; The support shaft is formed with a keyway that cooperates with the connecting key;

The connecting key has a second protrusion, and the surface of the second protrusion is a truncated cylindrical shape with the rotation axis of the rotating structure as the central axis.
The rotary guide tool according to any one of claims 3 to 5, wherein the revolute joint further comprises a third protrusion formed at an end of the connecting key that is away from the forward end of the support shaft;

The third protrusion has a second truncated spherical surface that is concentric with the first truncated spherical surface;

The support shaft has a third groove, and the third groove and the third protrusion cooperate with the second cross-sectional spherical surface to form a spherical pair.
The rotary guide tool according to any one of claims 2 to 5, wherein one end of the flexible member is mounted on a fixed portion of the support shaft, and the other end of the flexible member is The transmission shaft is supported by a supporting part; the rotation center of the rotating structure is located between the fixed part and the supporting part.
The rotary guide tool according to any one of claims 1 to 5, further comprising an annular pressure balance portion connecting the inner wall of the support shaft and the outer wall of the transmission shaft, and a part of the inner wall of the support shaft A part of the outer wall of the transmission shaft and the inner surface of the pressure balance part jointly define a medium cavity.
The rotary guide tool according to claim 1, wherein the shortest distance between the center of rotation and the tail end of the drill bit is not greater than 3.5 times the maximum radial dimension of the support shaft.
A transmission device connected separately:

The power unit has an output shaft capable of outputting torque and an offset driving part capable of outputting radial force;

Drill bit, with the end of the drill bit;

It is characterized by:

A transmission shaft coaxially connected with the output shaft;

A support shaft coaxially connected with the transmission shaft through a rotating structure, the rotation axis of the rotating structure is perpendicular to the axis of the output shaft; the support shaft has

The accommodating cavity and the forward and rearward ends formed at both ends of the accommodating cavity; the rotation center of the rotating structure is located in the accommodating cavity; the rear end of the supporting shaft can be biased Driven by the radial force output by the driving part; the forward end and the drill bit are coaxially connected to the drill bit tail end.