Screw drilling tools

Abstract

The present application discloses a screw drill tool, which belongs to the field of oil drilling and well repair. One end of the bypass valve assembly in the screw drill tool is connected to one end of the anti-drop assembly; the anti-drop assembly includes an anti-drop short circuit and an anti-drop pull rod located in the anti-drop short circuit; the stator in the motor assembly includes a stator tube and a right-handed spiral rubber bushing located inside the stator tube, the right-hand rotor is located in the stator tube, one end of the right-hand rotor is threadedly connected to one end of the anti-drop pull rod through a right-handed thread, and the stator tube is threadedly connected to the anti-drop short circuit through a left-handed thread; one end of the universal shaft in the universal shaft assembly is connected to one end of the right-hand rotor, and the universal shaft housing is connected to the stator tube; one end of the transmission shaft in the transmission shaft assembly is connected to the other end of the universal shaft, and the other end of the transmission shaft is used to connect to the drill bit. The invention solves the problem that the connection of each component of the screw drill tool in the related art is easy to loosen, and achieves the effect of improving the tightness between the components of the screw drill tool.

Description

Technical Field

[0001] The present application relates to the field of oil well drilling and repair, and in particular to a screw drilling tool. Background Art

[0002] To extract crude oil, natural gas, or underground mineral deposits buried deep within the earth, mechanical equipment is first used to create a cylindrical hole of a certain depth. This step in oil extraction operations is known as drilling. A common drilling method is rotary drilling, which utilizes the cutting or grinding action of the rotating drill bit to break up rock. A screw drill is a positive displacement downhole power drilling tool that uses drilling fluid as a power source, converting the fluid's pressure energy into mechanical energy. The screw drill, when connected to the drill bit, increases the drilling speed.

[0003] A screw drill tool in the related art includes a bypass valve assembly, an anti-drop assembly, a motor assembly, a universal shaft assembly, and a drive shaft assembly. The drive shaft is coaxially connected to the drill bit. During operation, mud, water, or other media is injected into the screw motor, causing the screw motor to drive the universal shaft and drive shaft, which in turn rotates the drill bit, converting liquid pressure energy into mechanical energy.

[0004] However, during use of the screw drill in the related art, the connections between the various components are prone to loosening. Summary of the Invention

[0005] The embodiment of the present application provides a screw drill. The technical solution is as follows:

[0006] In a first aspect, a screw drill is provided, the screw drill comprising a bypass valve assembly, an anti-drop assembly, a motor assembly, a universal shaft assembly, and a transmission shaft assembly;

[0007] One end of the bypass valve assembly is connected to one end of the anti-drop assembly;

[0008] The anti-drop assembly includes an anti-drop short circuit and an anti-drop pull rod located in the anti-drop short circuit;

[0009] The motor assembly includes a stator and a right-hand rotor, the stator includes a stator tube and a right-hand spiral rubber bushing located inside the stator tube, the right-hand rotor is located in the stator tube, one end of the right-hand rotor is threadedly connected to one end of the anti-drop pull rod through a right-hand thread, and the stator tube is threadedly connected to the anti-drop short-circuit through a left-hand thread;

[0010] The cardan shaft assembly includes a cardan shaft housing and a cardan shaft located in the cardan shaft housing, one end of the cardan shaft is connected to one end of the right-hand rotor, and the cardan shaft housing is connected to the stator tube;

[0011] The transmission shaft assembly includes a transmission shaft housing and a transmission shaft located in the transmission shaft housing. One end of the transmission shaft is connected to the other end of the universal shaft, and the other end of the transmission shaft is used to connect to a drill bit.

[0012] Optionally, the anti-drop assembly further includes an anti-drop nut and an anti-drop baffle, and the anti-drop short circuit includes a first pipe segment and a second pipe segment connected thereto, wherein the inner diameter of the second pipe segment is smaller than the inner diameter of the first pipe segment;

[0013] The other end of the anti-drop pull rod passes through the opening and is connected to the anti-drop baffle and the anti-drop nut in sequence through a right-handed thread. The outer diameter of the anti-drop baffle is larger than the inner diameter of the second pipe section, and the diameter of the anti-drop pull rod is smaller than the inner diameter of the second pipe section.

[0014] Optionally, the other end of the transmission shaft has a left-hand thread buckle according to American Petroleum Institute standards.

[0015] Optionally, one end of the bypass valve assembly is connected to the anti-drop short-circuit thread through a left-hand thread.

[0016] Optionally, the right-hand rotor is machined by a disc milling cutter, and the angle direction of the machining axis of the disc milling cutter is opposite to the angle direction when machining the left-hand rotor, and the angle ranges from 5 degrees to 80 degrees.

[0017] Optionally, the right-handed spiral rubber bushing in the stator is formed by setting a core shaft in the stator tube and injecting rubber into the stator tube. The core shaft is processed by a disc milling cutter, and the direction and range of the angle of the processing axis of the disc milling cutter are the same as the direction and range of the angle when processing the right-handed rotor.

[0018] Optionally, the surfaces of the core shaft and the rotor are swung in two directions along the included angle of the machining axis by a polishing machine, and the swing angle is -60 degrees to 60 degrees.

[0019] Optionally, the cross section of the stator has equidistant lines of short-amplitude hypocycloids.

[0020] Optionally, the cross section of the right-hand rotor is a conjugate curve of the equidistant line of the short-amplitude hypocycloid.

[0021] Optionally, the anti-drop assembly further includes a shock-absorbing structure, and the shock-absorbing structure is located on a side of the anti-drop baffle facing the rotor.

[0022] The technical solutions provided by the embodiments of the present application may have the following beneficial effects:

[0023] Provided is a screw drill comprising a bypass valve assembly, an anti-drop assembly, a motor assembly, a universal joint assembly, and a transmission shaft assembly. The bypass valve assembly is connected to the anti-drop assembly, and the stator is connected to the anti-drop short-circuit thread via a left-handed thread. The right-hand rotor in the motor assembly is meshed with the stator. After the power fluid is injected, the rotor rotates, converting the pressure energy of the power fluid into mechanical energy. The universal joint assembly converts the eccentric motion of the right-hand rotor into a fixed-axis rotation of the transmission shaft and then transmits the power to the transmission shaft assembly. The transmission shaft assembly transmits the power to the drill bit connected thereto. During drilling operations, when reverse drilling is encountered, the screw drill can rotate counterclockwise. During the rotation of the drill bit, the left-handed thread connection becomes tighter and tighter. This solves the problem of easy loosening of the connections of the various components of the screw drill in the related art, and achieves the effect of improving the tightness between the various components of the screw drill. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0025] Figure 1 This is a structural diagram of a screw drill provided in an embodiment of the present application;

[0026] Figure 2 This is a schematic structural diagram of another screw drill provided in an embodiment of the present application;

[0027] Figure 3 for Figure 2 Schematic diagram of the local structure of the medium screw drilling tool;

[0028] Figure 4 for Figure 2 Cross-section of the motor assembly of a mid-screw drill.

[0029] The above drawings illustrate specific embodiments of the present application, which will be described in more detail below. These drawings and the textual description are not intended to limit the scope of the present application in any way, but rather to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0030] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0031] The power fluid of the screw drill can be mud or clean water. The power fluid is pumped into the screw drill through the mud pump, and then enters the screw motor through the center hole of the pipe string. The screw motor converts the liquid pressure energy of the power fluid into mechanical energy, and transmits the mechanical energy of the motor to the drill bit through the transmission shaft. During the downhole drilling process, the screw drill serves as a channel for conveying high-pressure working medium and a rod to support the drill bit's counter-torque. When the drill head rotates, the screw drill does not rotate.

[0032] The underground rock environment is complex. During the drilling process, when encountering a harder rock layer or inclined rock breaking is required, the drill bit's rotary motion rotates irregularly, or reverses due to the obstruction of hard materials. During the reversal operation, the reverse force of the drill bit is applied to the screw drill, causing the various components in the screw drill connected to the drill bit to loosen under the reverse force, resulting in a weakening of the power transmission capacity between the screw drill components. After the power of the motor is transmitted to the drill bit, the drill bit's drilling ability is reduced, making it more difficult to break the already hard rock. Drilling needs to be suspended, and the screw drill needs to be pulled out and the various components need to be inspected and tightened.

[0033] Furthermore, the reverse force acting on the various components of the screw drill string connected to the drill bit can also cause the screw drill string to break and fracture. Once the screw drill string breaks, it will fall into the wellbore, requiring drilling to be suspended. Downhole salvage tools are then used to salvage the broken wellbore and other loosened screw drill string components that have fallen into the rock fissures. The screw drill string and drill bit can then be replaced and drilling operations can resume. This salvaging process is time-consuming and labor-intensive, increasing drilling costs and impacting oil production progress.

[0034] The embodiments of the present application provide a screw drill that can solve the problems existing in the above-mentioned related technologies.

[0035] Figure 1 It is a structural schematic diagram of a screw drill provided in an embodiment of the present application.

[0036] The screw drilling tool includes a bypass valve assembly 10 , an anti-drop assembly 20 , a motor assembly 30 , a universal joint shaft assembly 40 and a transmission shaft assembly 50 .

[0037] One end of the bypass valve assembly 10 is connected to one end of the anti-drop assembly 20 .

[0038] The anti-drop assembly 20 includes an anti-drop short circuit 21 and an anti-drop pull rod 22 located in the anti-drop short circuit 21 .

[0039] The motor assembly 30 includes a stator 31 and a right-handed rotor 32. The stator 31 includes a stator tube 311 and a right-handed spiral rubber bushing 312 located inside the stator tube 311. The right-handed rotor 32 is located in the stator tube 311. One end of the right-handed rotor 32 is threadedly connected to one end of the anti-drop pull rod 22 through a right-handed thread, and the stator tube 311 is threadedly connected to the anti-drop short circuit 21 through a left-handed thread.

[0040] The cardan shaft assembly 40 includes a cardan shaft housing 41 and a cardan shaft 42 located in the cardan shaft housing 41 . One end of the cardan shaft 42 is connected to one end of the right rotor 32 , and the cardan shaft housing 41 is connected to the stator tube 311 .

[0041] The transmission shaft assembly 50 includes a transmission shaft housing 51 and a transmission shaft 52 located in the transmission shaft housing 51 . One end of the transmission shaft 52 is connected to the other end of the universal shaft 42 , and the other end of the transmission shaft 52 is used to connect to the drill bit.

[0042] In summary, the embodiment of the present application provides a screw drill comprising a bypass valve assembly, an anti-drop assembly, a motor assembly, a universal joint assembly and a transmission shaft assembly, wherein the bypass valve assembly is connected to the anti-drop assembly, the stator is connected to the anti-drop short-circuit thread via a left-handed thread, the right-hand rotor in the motor assembly is meshed with the stator, and after the power fluid is injected, the rotor rotates, converting the pressure energy of the power fluid into mechanical energy, the universal joint assembly converts the eccentric motion of the right-hand rotor into a fixed-axis rotation of the transmission shaft and then transmits the power to the transmission shaft assembly, and the transmission shaft assembly transmits the power to the drill bit connected thereto. During drilling operations, when reverse drilling is encountered, the screw drill can rotate counterclockwise, and during the rotation of the drill bit, the left-handed thread connection becomes tighter and tighter. The problem of easy loosening of the connections of the various components of the screw drill in the related art is solved, and the effect of improving the tightness between the various components of the screw drill is achieved.

[0043] Optionally, the anti-drop assembly further includes an anti-drop nut and an anti-drop baffle, and the anti-drop short circuit includes a first pipe segment and a second pipe segment connected thereto, wherein the inner diameter of the second pipe segment is smaller than the inner diameter of the first pipe segment;

[0044] The other end of the anti-drop pull rod passes through the opening and is connected to the anti-drop baffle and the anti-drop nut in sequence through right-hand threads. The outer diameter of the anti-drop baffle is larger than the inner diameter of the second pipe section, and the diameter of the anti-drop pull rod is smaller than the inner diameter of the second pipe section.

[0045] Optionally, the other end of the drive shaft has an API standard left-hand thread lock.

[0046] Optionally, one end of the bypass valve assembly is connected to the anti-drop short-circuit thread through a left-hand thread.

[0047] Optionally, the right-hand rotor is machined by a disc milling cutter, and the angle direction of the machining axis of the disc milling cutter is opposite to the angle direction when machining the left-hand rotor, and the angle ranges from 5 degrees to 80 degrees.

[0048] Optionally, the right-handed spiral rubber bushing in the stator is formed by setting a core shaft in the stator tube and injecting rubber into the stator tube. The core shaft is processed by a disc milling cutter, and the direction and range of the angle of the processing axis of the disc milling cutter are the same as the direction and range of the angle when processing the right-handed rotor.

[0049] Optionally, the surfaces of the core shaft and the rotor are swung in two directions along the included angle of the machining axis by a polishing machine, and the swing angle is -60 degrees to 60 degrees.

[0050] Optionally, the cross section of the stator has equidistant lines of short-amplitude hypocycloids.

[0051] Optionally, the cross section of the right-hand rotor is a conjugate curve of the equidistant line of the short-amplitude hypocycloid.

[0052] Optionally, the anti-drop assembly further includes a shock-absorbing structure, which is located on a side of the anti-drop baffle facing the rotor.

[0053] Please refer to Figure 2 , which shows a structural schematic diagram of another screw drill provided in an embodiment of the present application.

[0054] Optionally, the other end of the drive shaft 52 has a left-hand thread buckle 521 according to the American Petroleum Institute standard. The drive shaft 52 is located in the drive shaft housing 51. One end of the drive shaft 52 is connected to the other end of the universal joint 42, and bears the force applied by the motor assembly 30 transmitted by the universal joint 42. The other end of the drive shaft 52 is connected to the drill bit (not shown in the figure). The drive shaft 52 directly transmits the power of the screw drill to the drill bit. Therefore, the drive shaft 52 is an important component of the screw drill. If an ordinary threaded connection buckle is used, during the drilling process of the drill bit, if hard rock formations are encountered, the rotary motion of the drill bit operates irregularly, or the drill bit reverses due to the obstruction of hard materials, the other end of the drive shaft 52 directly receives the force of the drill bit's reversal, and the other end of the drive shaft 52 will produce a thread on the other end of the drive shaft that follows the drill bit's reversal, thereby loosening the thread. When using the left-hand buckle of the American Petroleum Institute standard in the embodiment of the present application, when the drill bit is reversed, the left-hand buckle at the other end of the drive shaft 52 will be turned tighter and tighter, that is, the connection between the other end of the drive shaft 52 and the drill bit will become more and more firm, thereby avoiding the drill bit's drilling ability being reduced or the drill bit falling due to loosening of the connecting parts.

[0055] The American Petroleum Institute (API), the leading trade promotion organization for the U.S. oil and gas industry, has established numerous industry standards and recommendations covering all aspects of the oil and gas industry. The left-hand threaded fasteners used in this embodiment comply with the API's standards for left-hand threaded fasteners.

[0056] The cardan shaft assembly 40 includes a cardan shaft housing 41 and a cardan shaft 42 located in the cardan shaft housing 41. The cardan shaft assembly 40 connects the motor assembly 30 and the drive shaft assembly 50. As a transfer assembly for power transmission, the cardan shaft assembly 40 can convert the eccentric motion of the motor assembly 30 into the fixed-axis rotation of the drive shaft 52. The cardan shaft 42 in the embodiment of the present application is a flexible-axis cardan shaft, and a petal-type cardan shaft or a ball-jointed cardan shaft can also be used. The specific form of the cardan shaft is not limited in the embodiment of the present application.

[0057] One end of the universal shaft 42 in the universal shaft assembly 40 is threadedly connected to one end of the right-hand rotor 32 through a left-hand thread. When the drill bit rotates irregularly or reverses due to the obstruction of hard materials, the connection between the universal shaft 42 and one end of the right-hand rotor 32 will become tighter and tighter, and the threaded connection will be more secure, avoiding the weakening of the power transmission of the screw drill tool due to loose connection between the universal shaft assembly 40 and the motor assembly 30.

[0058] The universal joint housing 41 in the universal joint assembly 40 is threadedly connected to the stator tube 311 via a left-handed thread. If the drill bit rotates erratically or reverses due to an obstruction from a hard object, the connection between the universal joint housing 41 and one end of the stator tube 311 tightens with rotation, further strengthening the threaded connection and preventing the screw drill from weakening its power transmission due to a loose connection between the universal joint assembly 40 and the motor assembly 30.

[0059] Optionally, one end of the bypass valve assembly 10 is connected to the anti-drop short-circuit thread via a left-hand thread. The other end of the bypass valve assembly 10 is connected to a power fluid injection pump (not shown in the figure). The bypass valve assembly 10 may include a valve body, a valve sleeve, a valve core, and a spring. When the power fluid is injected into the screw drill, the valve core slides in the valve sleeve under the action of the liquid pressure. The sliding movement of the valve core can change the flow direction of the power fluid, thereby placing the bypass valve assembly 10 in an open or closed state. That is, during the drilling operation, the valve sleeve and the valve body through-hole are not closed, and the bypass valve assembly is in an open state. When the power fluid is injected, the power fluid can enter the anti-drop assembly 20 through the bypass valve assembly 10, and then enter the motor assembly 30 from the anti-drop assembly 20. The motor assembly 30 converts the pressure energy. When the flow rate and pressure of the power fluid reach the preset value, the valve core moves downward, the valve body through-hole of the bypass valve assembly 10 closes, and the bypass valve assembly 10 is in a closed state.

[0060] The flow rate of the power fluid injected by the bypass valve assembly 10 is related to the power value generated by the motor assembly 30. When the power fluid flow rate is large, the power generated by the motor assembly 30 is greater, and thus the power provided to the drill bit is greater. Therefore, whether the internal structure of the bypass valve assembly 10 can operate normally is particularly important. Before using the screw drill provided by the embodiment of the present application for drilling, the bypass valve assembly 10 in the screw drill can also be inspected to see whether the power fluid can flow, in order to prevent the power fluid injected by the bypass valve assembly from not flowing normally after being lowered into the well. The bypass valve assembly can be put into use after passing the inspection. In addition, the bypass valve assembly can also include other components that can improve the performance of the bypass valve assembly and ensure the flow rate of the power fluid, which is not limited in the embodiment of the present application.

[0061] Figure 3 for Figure 2 Schematic diagram of the local structure of the medium screw drilling tool, Figure 3 Schematic diagram of the structure of the motor assembly 30 and the anti-drop assembly 20.

[0062] The motor assembly 30 includes a stator 31 and a right-hand rotor 32. The motor assembly 30 is a component that provides power to the drill bit. The stator 31 and the right-hand rotor 32 in the motor assembly 30 can engage with each other when the power fluid is injected, wherein the stator 31 is connected to the sleeve in the motor assembly 30, that is, the stator 31 is usually fixed on the inside of the screw drill bit. When the stator 31 and the right-hand rotor 32 are engaged, the stator 31 is in a non-moving state. The right-hand rotor 32 is usually a spiral rod with a spiral structure on it. When the power fluid is injected, the rotor rotates and engages with the stator during rotation. The lead difference between the right-hand rotor 32 and the stator 31 is used to form a spiral sealing chamber to convert the pressure energy of the power fluid into mechanical energy, thereby providing power to the drill bit.

[0063] Optionally, the right-hand rotor 32 is processed by a disc milling cutter, and the angle direction of the machining axis of the disc milling cutter is opposite to the angle direction when machining the left-hand rotor, and the angle ranges from 5 degrees to 80 degrees. The right-hand rotor 32 is located in the stator tube 311, and one end of the right-hand rotor 32 is threadedly connected to one end of the anti-drop pull rod 22 through a right-handed thread. The right-hand rotor 32 can choose a corrosion-resistant and high-hardness screw rod, and the screw rod is milled to form a right-handed thread. The milling cutter is a rotating tool with one or more teeth, wherein the disc milling cutter can mill large end faces due to its large diameter. In this application, milling is performed on the screw rod, and the milling area is large. The use of a disc milling cutter can increase the milling speed. The disc milling cutter can be used on a vertical milling machine, an end milling machine or a gantry milling machine. The specific milling machine specifications and models are not limited in this embodiment of the application.

[0064] Since the right-hand rotor 32 in the embodiment of the present application has a different spiral direction from the rotor in the related art, when manufacturing the right-hand rotor 32 in the embodiment of the present application, the milling machine and the disc milling cutter for processing the right-hand rotor must be adjusted first. The angle direction of the machining axis of the disc milling cutter is opposite to the angle direction when processing the left-hand rotor. At this time, the milling machine is started, and the teeth of the disc milling cutter intermittently cut off the excess of the screw during operation, so that the screw forms evenly distributed inclined protrusions and depressions, thereby forming the right-hand rotor 32. The angle range between the disc milling cutter and the machining axis is 5 degrees to 80 degrees. Within the above angle range, a right-hand rotor 32 spiraling to the right can be processed. The spiral line of the right-hand rotor 32 can include a single-head or multi-head spiral line. The fewer the number of heads of the right-hand rotor 32, the higher the speed and the smaller the torque; the more the number of heads, the lower the speed and the greater the torque. The number of heads of the right-hand rotor 32 is not limited in the embodiment of the present application.

[0065] The stator 31 includes a stator tube 311 and a right-handed spiral rubber bushing 312 located inside the stator tube 311. The stator tube 311 is threadedly connected to the anti-drop short circuit 21 via a left-handed thread connection. The threaded connection buckle between the stator tube 311 and the anti-drop short circuit 21 complies with the API standard. The stator in the related art is usually connected to the bypass valve. In the embodiment of the present application, in order to prevent the screw drill from falling into the well, an anti-drop assembly 20 is further provided between the bypass valve assembly and the motor assembly. After the stator tube 311 of the stator 31 is connected to the anti-drop assembly 20, it can prevent the motor assembly 30 from falling into the well when the casing of the screw drill breaks.

[0066] Optionally, the right-handed spiral rubber bushing 312 in the stator 31 is formed by cooling the rubber after the mandrel is set in the stator tube 311 and the rubber is injected into the stator tube 311. The mandrel is processed by a disc milling cutter, and the direction of the machining axis angle of the disc milling cutter is the same as the direction and range of the angle when processing the right-handed rotor. Because the right-handed rotor 32 rotates in the stator 31. The better the fixation of the stator 31, the longer the service life of the motor assembly 30. Therefore, in order to avoid the stator 31 and the screw drill being loosely fixed and causing the stator 31 to fall off, the rubber injected into the mandrel can be heated to a flowable state. After the mandrel is set in the stator tube 311, the heated flowable rubber is injected into the stator tube 311. After the rubber is cooled and formed, the stator 31 firmly connected to the screw drill casing can be formed. The core shaft in the stator 31 determines the overall shape of the stator 31. In order to enable the stator 31 and the right-hand rotor 32 to be tightly engaged, when manufacturing the core shaft in the stator 31, the direction of the machining axis angle of the disc milling cutter can be the same as the direction of the angle when machining the right-hand rotor, and the range of the angle is also the same. The range of the angle in the embodiment of the present application is any value between 5 degrees and 80 degrees. The specific angle value is not limited in the embodiment of the present application.

[0067] Optionally, the surface of the mandrel and the right-hand rotor 32 is swung along the machining axis angle in two directions by a polishing machine, and the swing angle is -60 degrees to 60 degrees. Because the mandrel and the right-hand rotor 32 surfaces after the disc milling cutter is cut may be relatively rough, when the mandrel surface is relatively rough, the injected rubber may be caused to form a rough uneven surface after cooling, thereby affecting the engagement and sealing effect of the stator 31 and the right-hand rotor 32, therefore after the disc milling cutter is machined, it is also necessary to grind and polish the surface of the right-hand rotor 32 and the surface of the mandrel to make its surface smooth and flat. In the embodiment of the present application, a polishing machine is used to polish, the mandrel or the right-hand rotor 32 is rotated at a high speed by a sponge or wool polishing disc installed on the polishing machine, the polishing disc and polishing agent act together and rub against the mandrel or the right-hand rotor 32, thereby removing the pollution and shallow marks on the mandrel or the right-hand rotor 32 surfaces, so that the stator 31 and the right-hand rotor 32 can be better engaged.

[0068] Figure 4 for Figure 2 The cross-sectional view of the motor assembly of the mid-screw drill tool shows that the stator 31 and the right-hand rotor 32 are engaged, that is, the right-hand rotor 32 rotates in the stator. The right-hand rotor 32 rotates around the axis and has multiple engagement points. The cavity closed by the multiple engagement points can form a sealed cavity. The volume of the cavity is constant. As the right-hand rotor 32 rotates in the stator 21, the sealed cavity gradually moves along the axis, which can convert the pressure energy of the power fluid into mechanical energy. The cross-sectional view between the stator and the right-hand rotor 32 when the right-hand rotor 32 rotates to different angles can be shown as follows. Figure 4 shown.

[0069] Optionally, the cross section of the stator 31 has equidistant lines of short hypocycloids. Short hypocycloids are the trajectory of a point within and fixed to a moving circle (generating circle) when it rolls purely along the inner side of a fixed circle (base circle) on a plane. Figure 4 As shown, in cross section, the right-hand rotor 32 rolls along the inner side of the stator 31 .

[0070] Optionally, the cross section of the right-hand rotor 32 is a conjugate curve of the equidistant line of the short hypocycloid. A conjugate curve refers to a pair of continuously tangent curves on two components used to achieve a given motion law. If the cross section of the stator 31 has an equidistant line of the short hypocycloid, the cross section of the right-hand rotor 32 is correspondingly a conjugate curve of the equidistant line of the short hypocycloid.

[0071] Optionally, the anti-drop assembly 20 includes an anti-drop short circuit 21 and an anti-drop pull rod 22 located in the anti-drop short circuit 21. The anti-drop assembly 20 also includes an anti-drop nut 23 and an anti-drop baffle 24. The anti-drop short circuit 21 includes a first pipe section 211 and a second pipe section 212 connected together. The inner diameter of the second pipe section 212 is smaller than the inner diameter of the first pipe section 211; the other end of the anti-drop pull rod 22 passes through the opening and is sequentially connected to the anti-drop baffle 24 and the anti-drop nut 23 through a right-hand thread. The outer diameter of the anti-drop baffle 24 is larger than the inner diameter of the second pipe section 212, and the diameter of the anti-drop pull rod is smaller than the inner diameter of the second pipe section. The first pipe section 211 of the anti-drop short circuit 21 is connected to the bypass valve assembly. When the sleeve of the screw drill bit breaks, since one end of the anti-drop rod 22 is connected to the motor assembly 30, the anti-drop baffle 24 is stuck in the second pipe section 212, and the anti-drop rod 22 is pulled so as not to fall downward, and the motor assembly 30 connected to the other end of the anti-drop rod 22 will not fall. As a result, the universal joint assembly connected to the motor assembly 30 and the drive shaft assembly connected to the universal joint assembly will not fall into the well, avoiding the need to stop the well to salvage dropped objects due to parts falling into the well, thereby improving the performance of the screw drill bit and the efficiency of oil production.

[0072] Optionally, the anti-drop assembly further includes a shock-absorbing structure, which is located on the side of the anti-drop baffle facing the rotor. Screw drill tools are typically made of steel or other alloy materials. For example, the screw drill tool may be made of tungsten alloy, and therefore are relatively heavy. When the casing breaks, the motor assembly, the universal joint assembly, and the transmission shaft assembly fall downward, and the anti-drop baffle moves downward until it is stuck on the second pipe section 212. The weight of the motor assembly, the universal joint assembly, and the transmission shaft assembly causes a large vibration force to be generated between the anti-drop baffle and the second pipe section 212. The shock-absorbing structure can reduce the vibration force between the anti-drop baffle and the second pipe section 212. Reducing this vibration force can avoid damage to the screw drill tool when the vibration force is generated.

[0073] In summary, the embodiment of the present application provides a screw drill comprising a bypass valve assembly, an anti-drop assembly, a motor assembly, a universal joint assembly and a transmission shaft assembly, wherein the bypass valve assembly is connected to the anti-drop assembly, the stator is connected to the anti-drop short-circuit thread via a left-handed thread, the right-hand rotor in the motor assembly is meshed with the stator, and after the power fluid is injected, the rotor rotates, converting the pressure energy of the power fluid into mechanical energy, the universal joint assembly converts the eccentric motion of the right-hand rotor into a fixed-axis rotation of the transmission shaft and then transmits the power to the transmission shaft assembly, and the transmission shaft assembly transmits the power to the drill bit connected thereto. During drilling operations, when reverse drilling is encountered, the screw drill can rotate counterclockwise, and during the rotation of the drill bit, the left-handed thread connection becomes tighter and tighter. The problem of easy loosening of the connections of the various components of the screw drill in the related art is solved, and the effect of improving the tightness between the various components of the screw drill is achieved.

[0074] The above description is merely an optional embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A screw drill, characterized in that: The screw drilling tool includes a bypass valve assembly, an anti-drop assembly, a motor assembly, a universal shaft assembly, a transmission shaft assembly and a shock absorbing structure; One end of the bypass valve assembly is connected to one end of the anti-drop assembly; The anti-drop assembly includes an anti-drop short circuit, an anti-drop pull rod located in the anti-drop short circuit, an anti-drop nut and an anti-drop baffle, the anti-drop short circuit includes a first pipe section and a second pipe section connected, the inner diameter of the second pipe section is smaller than the inner diameter of the first pipe section, the other end of the anti-drop pull rod passes through the opening of the anti-drop short circuit and is sequentially connected to the anti-drop baffle and the anti-drop nut through a right-hand thread, the outer diameter of the anti-drop baffle is larger than the inner diameter of the second pipe section, and the diameter of the anti-drop pull rod is smaller than the inner diameter of the second pipe section; The motor assembly includes a stator and a right-hand rotor, the stator includes a stator tube and a right-hand spiral rubber bushing located inside the stator tube, the right-hand rotor is located in the stator tube, one end of the right-hand rotor is threadedly connected to one end of the anti-drop pull rod through a right-hand thread, and the stator tube is threadedly connected to the anti-drop short-circuit through a left-hand thread. The right-hand rotor and the right-hand spiral rubber bushing can engage with each other when the power fluid is injected. When the stator and the right-hand rotor are engaged, the stator is in a non-moving state. The right-hand spiral rubber bushing is formed by setting a core shaft in the stator tube, injecting flowable rubber into the stator tube, and waiting for the rubber to cool and form. The surface of the core shaft and the surface of the right-hand rotor are respectively ground and polished by the polishing disk and polishing agent of the polishing machine; The cardan shaft assembly includes a cardan shaft housing and a cardan shaft located in the cardan shaft housing, one end of the cardan shaft is connected to one end of the right-hand rotor, and the cardan shaft housing is connected to the stator tube; The transmission shaft assembly includes a transmission shaft housing and a transmission shaft located in the transmission shaft housing, one end of the transmission shaft is connected to the other end of the universal shaft, and the other end of the transmission shaft is used to connect to the drill bit; The shock absorbing structure is located on a side of the anti-drop baffle facing the rotor, and is used to reduce the vibration force between the anti-drop baffle and the second pipe section of the anti-drop short circuit.

2. The screw drill according to claim 1, characterized in that: The other end of the transmission shaft has a left-hand thread thread according to the American Petroleum Institute standard.

3. The screw drill according to claim 1, characterized in that: One end of the bypass valve assembly is connected to the anti-drop short-circuit thread through a left-hand thread.

4. The screw drill according to claim 1, characterized in that: The right-hand rotor is machined by a disc milling cutter, and the included angle direction of the machining axis of the disc milling cutter is opposite to the included angle direction when machining the left-hand rotor, and the range of the included angle is 5 degrees to 80 degrees.

5. The screw drill according to claim 4, characterized in that: The core shaft is processed by a disc milling cutter, and the direction and range of the angle of the machining axis of the disc milling cutter are the same as the direction and range of the angle when processing the right-hand rotor.

6. The screw drill according to claim 5, characterized in that: The surfaces of the core shaft and the rotor are swung in two directions along the included angle of the machining axis by a polishing machine, and the swing angle is -60 degrees to 60 degrees.

7. The screw drill according to claim 1, characterized in that: The cross section of the stator has equidistant lines of short-amplitude hypocycloids.

8. The screw drill according to claim 7, characterized in that: The cross section of the right-hand rotor is a conjugate curve of the equidistant line of the short-amplitude hypocycloid.

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