A stuck-free screw drill string with improved torque transmission capacity

Abstract

The application relates to a stuck-free screw drill tool with improved torque transmission capacity, which comprises a drill tool shell, a drill tool shaft and a plurality of accommodating spaces for accommodating stoppers between the anti-falling shell and the anti-falling rod.

Description

Technical Field

[0001] This application relates to the field of screw drill technology, and in particular to a screw drill tool for improving torque transmission capability. Background Technology

[0002] In oil and gas extraction, screw drills are crucial tools for providing torque to the drill bit to break rock. During operation, drilling fluid is pumped into the stator housing of the screw drill, driving a rotor eccentric to the stator housing to rotate. The rotor then drives the universal joint and drive shaft connected to it to rotate, which in turn drives the drill bit connected to the lower end of the screw drill. Often, in addition to the drill bit, other drilling tools connected to the lower end of the screw drill include MWD (Mechanical Warp Drive), rotary steerable tools, and near-bit measurement instruments.

[0003] During drilling, due to wellbore instability or encountering complex, difficult-to-drill hard rock, wellbore collapse or excessive cutting resistance may occur, causing the rotary guide tool or drill bit to become stuck. The output torque of the screw drill motor may be insufficient to drive the bottom-hole tools, and an effective circulation channel cannot be established. For conventional drill string assemblies without screw drills, the usual practice after a drill bit gets stuck is to increase the torque of the surface rotary table. The surface rotary table drives the drill pipe to rotate, and when the torque is high enough, the drill bit is released. However, this method is not suitable for drill string assemblies with screw drills at the bottom of the well because the commonly used screw drill structure cannot transmit the torque from the stator housing to the drill bit.

[0004] When a screw drill string is stuck at the bottom of the well, common unsticking methods include shoveling and acid soaking. For example, pulling the drill pipe creates tensile stress on the stuck area, while the shoveling device generates impact force that is transmitted to the drill bit, thus unsticking it. If unsticking fails, the only option is to uncouple the drill bit, rotary steerable tool (MWD), and screw drill string at the safety joint, leaving them at the bottom of the well for retrieval. If retrieval fails, well backfilling and sidetracking are required. In such cases, besides the loss of some drill string components remaining at the bottom of the well, retrieval, well backfilling, and sidetracking also incur additional costly drilling operations, especially for expensive rotary steerable tools.

[0005] To solve the problem of unsticking in drilling using screw drills, the first existing patented technology is to install an unsticking device on the drive shaft or universal joint, such as Chinese patent CN212201973U. This unsticking design significantly weakens the strength of the drive shaft and universal joint, which will affect the service life of the drive shaft and universal joint or even cause them to break and fall into the well, creating new risks.

[0006] The second method uses steel balls or other objects to stop the jamming, as illustrated in Chinese patent CN212837577U. The steel balls fall into the space formed by the eccentric rotor and the inner hole of the housing. Due to the eccentric configuration of the rotor and housing centerlines, the rotor moves eccentrically around the stator housing, causing the steel balls to fall into only a portion of the space. The steel balls are asymmetrically arranged circumferentially, resulting in a small number of balls capable of releasing the jamming force and a relatively small transmittable release torque. Furthermore, during the release process, the upper end of the rotor bears significant lateral forces and bending loads, potentially damaging or deforming the stator rubber, causing lateral displacement of the rotor, and leading to the steel balls falling and resulting in release failure. Existing patented technologies cannot adequately meet the release force or reliability requirements under severe jamming conditions. Summary of the Invention

[0007] This application provides a release screw drill tool to improve torque transmission capability, in order to solve the problems in related technologies where the rotor moves eccentrically around the stator housing, the steel balls can only fall into a portion of the receiving space, resulting in an asymmetrical arrangement of the steel balls along the circumference, a small number of steel balls that play a release role, and a small release torque that can be transmitted. At the same time, during the release process, the upper end of the rotor is subjected to a large lateral force and bending load, the rotor generates lateral displacement, and the falling of the steel balls leads to release failure.

[0008] This application provides an embodiment of a screw release tool for improving torque transmission capability, comprising:

[0009] The drill bit housing includes a stator housing and an anti-drop housing connected coaxially, both of which are hollow tubular structures;

[0010] The drill bit shaft includes a rotor screw located in the stator housing and an anti-drop rod located in the anti-drop housing, as well as an upper universal joint connected to the rotor screw to convert the eccentric rotation of the rotor screw into the coaxial rotation of the anti-drop rod within the anti-drop housing;

[0011] The anti-drop housing and the anti-drop rod are provided with multiple accommodating spaces around the circumference for accommodating the jamming object. When it is necessary to release the jamming, the accommodating space is filled with the jamming object that transmits the torque of the drill housing to the drill shaft.

[0012] In some embodiments: the upper universal joint includes a lower universal joint located at the top of the rotor screw, an upper universal joint located at the bottom of the anti-drop rod, and a universal joint connecting rod movably connected between the lower universal joint and the upper universal joint;

[0013] The two ends of the universal joint extend into the lower universal joint and the upper universal joint respectively and are spherically rotatably connected to each other, and are provided with sealing sleeves that are sealed to the lower universal joint and the upper universal joint.

[0014] In some embodiments: the drill housing further includes an upper universal joint housing threadedly connected between the stator housing and the anti-drop housing, the upper universal joint being located within the upper universal joint housing;

[0015] The anti-drop rod extends into the upper universal joint housing at one end and is rotatably connected to the upper universal joint housing via a bearing.

[0016] In some embodiments: the bearing includes an outer bearing ring coaxially fixedly connected to the upper universal joint housing, and an inner bearing ring coaxially fixedly connected to the anti-drop rod, wherein the outer bearing ring and the inner bearing ring are provided with flow channels for drilling fluid.

[0017] In some embodiments: the receiving space includes a stop groove located on the inner wall of the anti-drop housing, the stop groove extending along the axial direction of the anti-drop housing; and

[0018] A stop surface located on the side wall of the anti-fall rod and cooperating with the stop groove, wherein the stop groove and the stop surface form the receiving space.

[0019] In some embodiments: a plurality of stop grooves are evenly distributed along the circumferential direction of the anti-drop housing, and a plurality of stop surfaces are evenly distributed along the circumferential direction of the side wall of the anti-drop rod, and the plurality of stop grooves and the plurality of stop surfaces form a plurality of receiving spaces.

[0020] In some embodiments: the locking element is a steel ball, the diameter of the locking element is greater than the minimum gap between the stop groove and the stop surface, and the diameter of the locking element is less than the maximum gap between the stop groove and the stop surface.

[0021] In some embodiments: a mud channel for flowing mud is provided inside the rotor screw along the axial direction of the rotor screw, a nozzle communicating with the mud channel is provided on the upper side wall of the rotor screw, and a bypass hole communicating with the mud channel is provided on the lower side wall of the rotor screw.

[0022] In some embodiments: the top of the anti-fall rod is provided with an anti-fall nut and an anti-fall washer, and the anti-fall housing is provided with a stop hole with a diameter smaller than the outer diameter of the anti-fall nut or the anti-fall washer, and the anti-fall rod is located in the stop hole.

[0023] In some embodiments: the drill housing further includes a lower universal joint housing and a drive shaft housing located at the bottom of the stator housing, and the drill shaft further includes a lower universal joint connected to the rotor screw located in the lower universal joint housing, and a drive shaft connected to the lower universal joint located in the drive shaft housing.

[0024] The beneficial effects of the technical solution provided in this application include:

[0025] This application provides a freeing screw drill bit with improved torque transmission capability. The freeing screw drill bit includes a drill bit housing comprising a stator housing and an anti-drop housing coaxially connected, both being hollow tubular structures. It also includes a drill bit shaft comprising a rotor screw located within the stator housing and an anti-drop rod located within the anti-drop housing, as well as an upper universal joint connected to the rotor screw to convert the eccentric rotation of the rotor screw into coaxial rotation of the anti-drop rod within the anti-drop housing. Multiple circumferential spaces are provided between the anti-drop housing and the anti-drop rod to accommodate stuck objects. When freeing is required, these spaces are filled with the stuck objects that transmit the torque of the drill bit housing to the drill bit shaft.

[0026] Therefore, during normal operation, the rotor screw of this application converts the eccentric rotation of the rotor screw into the coaxial rotation of the anti-drop rod within the anti-drop housing via the universal joint, ensuring that all accommodating spaces are of equal size and that no jamming objects are placed within any of these spaces. When unjamming is required, a certain number of jamming objects are inserted into the drill pipe from the ground. These objects fall into multiple accommodating spaces between the anti-drop housing and the anti-drop rod. The drill pipe housing, through steel balls, drives the drill pipe shaft to rotate synchronously, transmitting the torque of the drill pipe housing to the drill pipe shaft, thus achieving reliable and rapid unjamming of the bottom drill pipe. A certain number of jamming objects can fall into multiple accommodating spaces and are symmetrically arranged circumferentially along the anti-drop rod. The large number of jamming objects and the large jamming surface enable the transmission of a relatively large rotary table torque, resulting in strong unjamming capability, high reliability, minimal damage to the motor rubber, and the ability for the unjammed screw drill pipe to continue to be used in the well. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the structure of an embodiment of this application during normal operation;

[0029] Figure 2 This is a schematic diagram of the structure in the card unlocking state according to an embodiment of this application;

[0030] Figure 3 for Figure 1 A cross-sectional view along the AA direction;

[0031] Figure 4 for Figure 2 A cross-sectional view along the BB direction.

[0032] Figure label:

[0033] 100. Drill tool housing; 110. Stator housing; 120. Anti-drop housing; 121. Accommodation space; 122. Stop groove; 130. Upper universal joint housing; 140. Lower universal joint housing; 150. Drive shaft housing; 160. Bearing; 161. Bearing outer ring; 162. Bearing inner ring; 163. Flow channel;

[0034] 200. Drill tool shaft; 210. Rotor screw; 211. Mud channel; 212. Nozzle; 213. Bypass hole; 220. Anti-drop rod; 221. Stop surface; 222. Shoulder; 223. Anti-drop nut; 224. Anti-drop washer; 230. Upper universal joint; 231. Universal joint connecting rod; 232. Lower universal joint; 233. Upper universal joint; 240. Lower universal joint; 250. Drive shaft; 300. Locking device. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0036] This application provides a release screw drill tool to improve torque transmission capability. It can solve the problems in related technologies where the rotor moves eccentrically around the stator housing, the steel balls can only fall into a part of the receiving space, resulting in the steel balls being asymmetrically arranged in the circumferential direction, the number of steel balls that play the role of release is small, the release torque that can be transmitted is small, and at the same time, during the release process, the upper end of the rotor is subjected to a large lateral force and bending load, the rotor generates lateral displacement, and the falling of steel balls leads to release failure.

[0037] See Figures 1 to 4 As shown in the figure, this application provides a screw release tool for improving torque transmission capability, comprising:

[0038] The drill housing 100 includes a stator housing 110 and a fall-prevention housing 120 coaxially connected. The fall-prevention housing 120 is located on top of the stator housing 110. Both the stator housing 110 and the fall-prevention housing 120 are hollow tubular structures.

[0039] The drill bit shaft 200 includes a rotor screw 210 located in the stator housing 110 and an anti-drop rod 220 located in the anti-drop housing 120, as well as an upper universal joint 230 connected to the rotor screw 210 and converting the eccentric rotation of the rotor screw 210 into the coaxial rotation of the anti-drop rod 220 within the anti-drop housing 120.

[0040] Multiple receiving spaces 121 are provided circumferentially between the anti-drop housing 120 and the anti-drop rod 220 to accommodate the locking object 300. The multiple receiving spaces 121 are the same size. When it is necessary to release the jamming, the multiple receiving spaces 121 are filled with the locking object 300 that transmits the torque of the drill housing 100 to the drill shaft 200.

[0041] In the normal operation of the release screw drill tool of this application embodiment, the rotor screw 210 converts the eccentric rotation of the rotor screw 210 into the coaxial rotation of the anti-drop rod 220 within the anti-drop housing 120 via the upper universal joint 230, so that each accommodating space 121 is the same size and no jamming object 300 is placed in the accommodating space 121. The anti-drop rod 220 and the anti-drop housing 120 are relatively independent and cannot rotate together.

[0042] When it is necessary to release the stuck drill bit, a certain number of locking objects 300 are dropped from the ground into the drill pipe. The locking objects 300 fall into multiple receiving spaces 121 between the anti-fall housing 120 and the anti-fall rod 220. The drill housing 100 drives the drill shaft 200 to rotate synchronously through the locking objects 300, and transmits the torque of the drill housing 100 to the drill shaft 200, so as to achieve reliable and fast release of the bottom drill bit.

[0043] When the screw is released, a certain number of locking objects 300 can fall into multiple receiving spaces 121 and be symmetrically arranged around the anti-drop rod 220. The number of locking objects 300 that play the role of releasing the screw is large and the locking surface is large, which can transmit a relatively large rotary table torque. The screw has strong release capability, high reliability, and minimal damage to the motor rubber. The screw drill can be used again after the screw is released.

[0044] In some alternative embodiments: see Figure 1 and Figure 2 As shown, this application provides an unlocking screw drill tool with improved torque transmission capability. The upper universal joint 230 of the unlocking screw drill tool includes a lower universal joint 232 located at the top of the rotor screw 210, an upper universal joint 233 located at the bottom of the anti-drop rod 220, and a universal joint connecting rod 231 movably connected between the lower universal joint 232 and the upper universal joint 233.

[0045] The two ends of the universal joint connecting rod 231 extend into the lower universal joint 232 and the upper universal joint 233 respectively, and are spherically rotatably connected to each other. Both ends of the universal joint connecting rod 231 are provided with sealing sleeves that are sealingly connected to the lower universal joint 232 and the upper universal joint 233. A lower sealing oil cavity is formed between the sealing sleeve and the lower universal joint 232, and grease for lubricating the lower universal joint 232 is provided in the lower sealing oil cavity. An upper sealing oil cavity is formed between the sealing sleeve and the upper universal joint 233, and grease for lubricating the upper universal joint 233 is provided in the upper sealing oil cavity.

[0046] In some alternative embodiments: see Figure 1 and Figure 2 As shown in the figure, this application provides a snagging screw drill bit with improved torque transmission capability. The drill bit housing 100 of the snagging screw drill bit also includes an upper universal joint housing 130 threadedly connected between the stator housing 110 and the anti-drop housing 120. The upper universal joint 230 is located inside the upper universal joint housing 130. One end of the anti-drop rod 220 near the upper universal joint 230 extends into the upper universal joint housing 130 and is rotatably connected to the upper universal joint housing 130 via a bearing 160.

[0047] The bearing 160 includes an outer bearing ring 161 coaxially fixedly connected to the upper universal joint housing 130, and an inner bearing ring 162 coaxially fixedly connected to the anti-drop rod 220. The outer bearing ring 161 and the inner bearing ring 162 are not only provided with bearing balls, but also with a flow channel 163 for drilling fluid. The flow channel 163 is used to guide the drilling fluid entering the anti-drop housing 120 into the stator housing 110, thereby driving the rotor screw 210 within the stator housing 110 to rotate eccentrically within the stator housing 110.

[0048] In this embodiment, the two ends of the upper universal joint housing 130 are respectively connected to the stator housing 110 and the anti-drop housing 120 by threads. The upper universal joint 230 is located inside the upper universal joint housing 130, which facilitates the assembly of the upper universal joint 230 with the rotor screw 210 and the anti-drop rod 220, as well as the assembly of the bearing 160 with the rotor screw 210 and the anti-drop rod 220.

[0049] In some alternative embodiments: see Figure 3 and Figure 4 As shown, this application embodiment provides a release screw drill tool to improve torque transmission capability. The receiving space 121 of the release screw drill tool includes a stop groove 122 located on the inner wall of the anti-drop housing 120, the stop groove 122 extending along the axial direction of the anti-drop housing 120; and a stop surface 221 located on the side wall of the anti-drop rod 220 and cooperating with the stop groove 122. The stop groove 122 and the stop surface 221 together form the receiving space 121.

[0050] Multiple stop grooves 122 are evenly distributed along the circumference of the anti-fall housing 120, and multiple stop surfaces 221 are evenly distributed along the circumference of the side wall of the anti-fall rod 220. The multiple stop grooves 122 and multiple stop surfaces 221 form multiple receiving spaces 121. The side wall of the anti-fall rod 220 is provided with a shoulder 222 to restrict the falling of the locking object 300. The shoulder 222 is located at the bottom of the stop surface 221. The gap between the shoulder 222 and the inner wall of the anti-fall housing 120 is smaller than the diameter of the locking object 300. When the locking object 300 falls onto the shoulder 222, it is stopped by the shoulder 222.

[0051] The locking element 300 is preferably a steel ball, but it is not limited to a regular steel ball; it can also be a rigid structure such as a cylinder or ellipse. The diameter of the locking element 300 is greater than the minimum gap between the stop groove 122 and the stop surface 221, and less than the maximum gap between the stop groove 122 and the stop surface 221. The stop groove 122 is an arc-shaped groove with a diameter greater than that of the locking element 300, and the stop surface 221 is a plane. The locking element 300 is located within the receiving space 121 formed by the stop groove 122 and the stop surface 221.

[0052] In some alternative embodiments: see Figure 1 and Figure 2 As shown in the figure, this application provides a release screw drill bit with improved torque transmission capability. The rotor screw 210 of this release screw drill bit has a mud channel 211 for mud flow along its axial direction. A nozzle 212 communicating with the mud channel 211 is provided on the upper sidewall of the rotor screw 210, and a bypass hole 213 communicating with the mud channel 211 is provided on the lower sidewall of the rotor screw 210.

[0053] When the drill bit gets stuck, and the rotor screw 210 is unable to pump drilling fluid, the mud channel 211, nozzle 212 and bypass hole 213 inside the rotor screw 210 can still establish a small-volume drilling fluid circulation channel to prevent the inability to start the pump after the drill bit gets stuck, the accumulation of cuttings at the bottom of the well and other reasons that prevent the drill bit from getting stuck.

[0054] An anti-fall nut 223 and an anti-fall washer 224 are provided at the top of the anti-fall rod 220. The anti-fall housing 120 has a stop hole with a diameter smaller than the outer diameter of the anti-fall nut 223 or the anti-fall washer 224, and the anti-fall rod 220 is located in the stop hole. The anti-fall rod 220, the anti-fall nut 223, and the anti-fall washer 224 are used to prevent the upper universal joint 230, the rotor screw 210, the lower universal joint 240, and the drive shaft 250 from falling into the well.

[0055] The drill housing 100 also includes a lower universal joint housing 140 and a drive shaft housing 150 located at the bottom of the stator housing 110. The drill shaft 200 also includes a lower universal joint 240 located in the lower universal joint housing 140 and connected to the rotor screw 210, and a drive shaft 250 located in the drive shaft housing 150 and connected to the lower universal joint 240.

[0056] Working principle

[0057] This application provides an unlocking screw drill bit with improved torque transmission capability. The unlocking screw drill bit includes a drill bit housing 100, which comprises a stator housing 110 and an anti-drop housing 120 coaxially connected, both of which are hollow tubular structures. A drill bit shaft 200 includes a rotor screw 210 located within the stator housing 110 and an anti-drop rod 220 located within the anti-drop housing 120.

[0058] And an upper universal joint 230 connected to the rotor screw 210 to convert the eccentric rotation of the rotor screw 210 into the anti-drop rod 220 coaxially rotating within the anti-drop housing 120; a plurality of receiving spaces 121 are provided on the circumference between the anti-drop housing 120 and the anti-drop rod 220 for accommodating the locking object 300. When it is necessary to release the jamming, the receiving space 121 is filled with the locking object 300 that transmits the torque of the drill housing 100 to the drill shaft 200.

[0059] Therefore, when the release screw drill tool of this application is working normally, the rotor screw 210 converts the eccentric rotation of the rotor screw 210 into the anti-drop rod 220 coaxially rotating within the anti-drop housing 120 through the upper universal joint 230, so that each accommodating space 121 is the same size and no jamming object is placed in the accommodating space 121.

[0060] When it is necessary to release the stuck drill bit, a certain number of locking objects 300 are dropped from the ground into the drill pipe. The locking objects 300 fall into multiple receiving spaces 121 between the anti-fall housing 120 and the anti-fall rod 220. The drill housing 100 drives the drill shaft 200 to rotate synchronously through the locking objects 300, and transmits the torque of the drill housing 100 to the drill shaft 200, so as to achieve reliable and fast release of the bottom drill bit.

[0061] A certain number of locking objects 300 can fall into multiple receiving spaces 121 and be symmetrically arranged circumferentially along the anti-drop rod 220. The number of locking objects 300 that play the role of unblocking is large and the locking surface is large, which can transmit a relatively large rotary table torque. It has strong unblocking ability, high reliability, and little damage to the motor rubber. Moreover, the screw drill bit can continue to be used in the well after unblocking.

[0062] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "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; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0063] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0064] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A free point screw drill string for improved torque transmission, characterized in that, The application relates to a torque transmission capacity improved unblocking screw drill tool. The torque transmission capacity improved unblocking screw drill tool comprises a drill tool shell (100), a drill tool shaft (200) and a blocking member (300). The drill tool shell (100) comprises coaxially connected stator shell (110) and anti-falling shell (120), and the stator shell (110) and the anti-falling shell (120) are both hollow tube structures. The drill tool shaft (200) comprises a rotor screw (210) located in the stator shell (110), an anti-falling rod (220) located in the anti-falling shell (120) and an upper universal shaft (230) connected with the rotor screw (210) and converting eccentric rotation of the rotor screw (210) into coaxial rotation of the anti-falling rod (220) in the anti-falling shell (120). A plurality of accommodating spaces (121) for accommodating the blocking member (300) are arranged on the circumference between the anti-falling shell (120) and the anti-falling rod (220), and the accommodating spaces (121) are filled with the blocking member (300) for transmitting the torque of the drill tool shell (100) to the drill tool shaft (200) when unblocking is needed. The upper universal shaft (230) comprises a lower universal joint (232) located at the top of the rotor screw (210), an upper universal joint (233) located at the bottom of the anti-falling rod (220) and a universal shaft connecting rod (231) movably connected between the lower universal joint (232) and the upper universal joint (233). The two ends of the universal shaft connecting rod (231) respectively extend into the lower universal joint (232) and the upper universal joint (233) and are connected with each other through spherical surface rotation, and sealing rubber sleeves are arranged in sealing connection with the lower universal joint (232) and the upper universal joint (233). The drill tool shell (100) further comprises an upper universal shaft shell (130) screw-connected between the stator shell (110) and the anti-falling shell (120), and the upper universal shaft (230) is located in the upper universal shaft shell (130). The end of the anti-falling rod (220) close to the upper universal shaft (230) extends into the upper universal shaft shell (130) and is rotatably connected with the upper universal shaft shell (130) through a bearing (160). The bearing (160) comprises a bearing outer ring (161) fixedly connected with the upper universal shaft shell (130) and a bearing inner ring (162) fixedly connected with the anti-falling rod (220), and a flow channel (163) for circulating drilling fluid is arranged between the bearing outer ring (161) and the bearing inner ring (162).

2. The torque transmission capacity improved unblocking screw drill tool according to claim 1, wherein the accommodating space (121) comprises a stop groove (122) located on the inner wall of the anti-falling shell (120), the stop groove (122) extends along the axial direction of the anti-falling shell (120), and a stop surface (221) located on the side wall of the anti-falling rod (220) and matched with the stop groove (122), the stop groove (122) and the stop surface (221) form the accommodating space (121).

3. The torque transmission capacity improved unblocking screw drill tool according to claim 2, wherein the stop groove (122) comprises a first stop groove (1221) and a second stop groove (1222), the first stop groove (1221) is located on the top of the anti-falling shell (120), the second stop groove (1222) is located on the bottom of the anti-falling shell (120), and the stop surface (221) comprises a first stop surface (2211) and a second stop surface (2212), the first stop surface (2211) is located on the top of the anti-falling rod (220), and the second stop surface (2212) is located on the bottom of the anti-falling rod (220). ​ The stop groove (122) is arranged along the circumferential direction of the anti-drop shell (120), and the stop surface (221) is arranged along the circumferential direction of the side wall of the anti-drop rod (220), and the plurality of stop grooves (122) and the plurality of stop surfaces (221) form a plurality of accommodation spaces (121).

4. The anti-stuck screw drill of claim 2 or 3, wherein: The stopper (300) is a steel ball, the diameter of the stopper (300) is greater than the minimum gap between the stop groove (122) and the stop surface (221), and the diameter of the stopper (300) is less than the maximum gap between the stop groove (122) and the stop surface (221).

5. The anti-stuck screw drill of claim 1, wherein: The rotor screw (210) is provided with a mud channel (211) for mud flow along the axial direction of the rotor screw (210), the upper end side wall of the rotor screw (210) is provided with a nozzle (212) in communication with the mud channel (211), and the lower end side wall of the rotor screw (210) is provided with a bypass hole (213) in communication with the mud channel (211).

6. The anti-stuck screw drill of claim 1, wherein: The top of the anti-drop rod (220) is provided with an anti-drop nut (223) and an anti-drop washer (224), the anti-drop shell (120) is provided with a stop hole with a diameter smaller than the outer diameter of the anti-drop nut (223) or the anti-drop washer (224), and the anti-drop rod (220) is located in the stop hole.

7. The anti-stuck screw drill of claim 1, wherein: The drill tool shell (100) further comprises a lower universal shaft shell (140) and a transmission shaft shell (150) at the bottom of the stator shell (110), and the drill tool shaft (200) further comprises a lower universal shaft (240) connected with the rotor screw (210) in the lower universal shaft shell (140), and a transmission shaft (250) connected with the lower universal shaft (240) in the transmission shaft shell (150).

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