Screw drill motor stator, screw drill motor and forming method

Abstract

The invention relates to the field of petroleum and natural gas drilling tools, in particular to a screw drill motor stator, a screw drill motor and a forming method.The screw drill motor stator comprises a stator body, a rubber bushing is installed on the inner wall of the stator body, and a first spiral structure is arranged on the inner surface of the rubber bushing; in the stator body, sheaths are arranged at the two ends of the rubber bushing, the outer surfaces of the sheaths are fixedly connected with the stator body, and second spiral structures are arranged on the inner surfaces of the sheaths; the spiral line type of the first spiral structure is the same as the spiral line type of the second spiral structure. According to the motor stator, the second threaded surface is arranged on the inner surface of the sheath, so that the speed and the flow of drilling fluid passing through the motor stator can be increased on the basis of protecting the rubber bushing, and the motor stator has the advantage of improving the descending efficiency of the drilling fluid.

Description

Technical Field

[0001] This invention relates to the field of oil and gas drilling tools, specifically to a screw drill motor stator, a screw drill motor, and a forming method thereof. Background Technology

[0002] Screw drills are a type of volumetric downhole power tool that uses drilling fluid as a power source to convert hydraulic energy into mechanical energy. Due to their simple structure, reliable operation, wide range of speed and torque adaptability, and high drilling efficiency, they are widely used in drilling projects in oil and natural gas.

[0003] As the power core of screw drilling tools, the motor stator has played a leading role in terms of performance, efficiency, adaptability, innovation and reliability. With the complex and ever-changing market environment, oilfield customers have put forward higher requirements for stator optimization design, rubber performance improvement and reliability enhancement, thus promoting the rapid and comprehensive development of stator innovation.

[0004] Chinese patent application CN116181221A discloses a screw drill bit resistant to erosion from sand-containing mud, including a motor assembly and a drive shaft assembly. The motor assembly includes a stator and a rotor. A rubber bushing is fixedly installed on the inner wall of the stator. The rotor has an axially hollow structure. The inner surface of the rubber bushing and the outer surface of the rotor are both helical surfaces. A centering sleeve is installed on the inner wall of the stator at both ends of the rubber bushing. This improves the erosion resistance of the motor stator and drive shaft, enabling them to maintain a longer service life under harsh drilling conditions.

[0005] However, because the structure has centralizing sleeves installed at both ends of the rubber bushing, the drilling fluid efficiency during the downward movement of the screw drill bit is low.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] To address the technical problems existing in the prior art, the present invention provides a screw drill motor stator, a screw drill motor, and a molding method. The motor stator of the present invention has a second threaded surface on the inner surface of the sheath, which not only protects the rubber bushing but also increases the speed and flow rate of drilling fluid through the motor stator, thus improving the efficiency of drilling fluid flow.

[0008] This invention includes the following technical solutions:

[0009] The first aspect of the present invention provides a stator for a screw drill motor, including a stator body, a rubber bushing installed on the inner wall of the stator body, a first helical structure provided on the inner surface of the rubber bushing, a protective sleeve provided at both ends of the rubber bushing in the stator body, the outer surface of the protective sleeve being fixedly connected to the stator body, and a second helical structure provided on the inner surface of the protective sleeve.

[0010] The spiral shape of the first spiral structure is the same as that of the second spiral structure.

[0011] Furthermore, the axial length of the sheath is 50mm to 150mm, and the difference between the radial thickness of the sheath and the radial thickness of the rubber bushing is -0.2mm to 0mm.

[0012] Furthermore, the inner surface of the rubber bushing is chamfered at the end.

[0013] Furthermore, the sheath is made of a temperature-resistant, wear-resistant, and high-elasticity modulus material;

[0014] Among them, the highest temperature resistance of the high temperature resistance and wear resistance material with high elastic modulus is 250℃, the coefficient of friction ranges from 0.1 to 0.4, and the elastic modulus ranges from 3GPa to 150GPa.

[0015] Furthermore, the temperature-resistant, wear-resistant, and high-elasticity modulus material includes polyimide, polyetheretherketone, or metal rings.

[0016] Furthermore, the surface of the sheath has been coated with a spray coating.

[0017] A second aspect of the present invention provides a screw drill motor, including a rotor and a screw drill motor stator as described above, wherein the outer surface of the rotor is provided with a helical surface, and the rotor is inserted into the screw drill motor stator.

[0018] A third aspect of the present invention provides a method for forming a stator of a screw drill motor, the method comprising the following steps:

[0019] The pre-formed stator body, rubber bushing, and sheath are obtained;

[0020] The rubber bushing and the sheath are fixed in the stator body to obtain the screw drill motor stator as described above.

[0021] Furthermore, the preforming process of the sheath includes:

[0022] Preparation work includes selecting machine tools, preparing cutting tools, preparing bar stock blanks with protective sleeves, and completing the relative position and fixation of the cutting tools and blanks.

[0023] The programming input involves writing the machining program and parameters for the bushing based on the internal cavity dimensions of the stator body and the helical shape of the first helical structure of the rubber bushing, and then inputting them into the machine tool system.

[0024] The spiral surface is machined by roughing, semi-finishing and finishing to complete the second spiral structure of the sheath;

[0025] The outer diameter is machined to complete the outer diameter dimensions, surface roughening, and activation of the sheath.

[0026] Furthermore, the sheath is connected to the stator body by means of adhesive or mechanical fastening.

[0027] By adopting the above technical solution, the present invention has the following advantages:

[0028] 1. When a screw drill bit is in operation, the high-pressure drilling fluid entering the motor stator cavity increases the impact force on the rubber bushing due to its high flow rate, causing deformation and even adhesive failure. Simultaneously, the impact of the rotor within the motor stator can easily damage the rubber bushing and adhesive layer. To protect these weak points of the motor stator, this invention adds a protective sleeve at each end of the rubber bushing. The flushing pressure of the drilling fluid and the impact of the rotor act on the protective sleeve first, effectively protecting the rubber. Furthermore, this protective sleeve incorporates a second helical structure, ensuring unobstructed drilling fluid flow and improving the efficiency of drilling fluid flow.

[0029] 2. The bushing of the motor stator of the present invention is made of a high-temperature resistant, wear-resistant and elastic modulus material. This not only effectively controls and protects the compression limit and adhesion of the rubber bushing, preventing premature irreversible plastic deformation and delamination of the rubber, but also avoids aging and spalling of the rubber bushing due to excessive local heat accumulation by reducing the amount of compression. This can significantly improve the adaptability and service life of the motor stator in downhole applications.

[0030] 3. The motor stator of the present invention has low molding difficulty, simple structure, and high working safety. It can be widely used in conventional screws, screws with equal wall thickness, and high temperature resistant screws, making it suitable for complex drilling fluids.

[0031] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention can be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a cross-sectional view of a screw drill motor stator according to an embodiment of the present invention;

[0034] Figure 2This is a schematic diagram of the structure of a screw drill motor stator according to an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of the structure of the rubber bushing and sheath in an embodiment of the present invention;

[0036] In the diagram, 10 is the stator body, 20 is the rubber bushing, and 30 is the sheath. Detailed Implementation

[0037] The following description provides many different embodiments or examples for implementing various features of the invention. The elements and arrangements described in the specific examples below are only for concise expression of the invention and are merely examples, not intended to limit the invention.

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] The first aspect of this embodiment provides a stator for a screw drill motor, such as... Figure 1 As shown, it includes a stator body 10, a rubber bushing 20 installed on the inner wall of the stator body 10, a first spiral structure provided on the inner surface of the rubber bushing 20, a protective sleeve 30 provided at both ends of the rubber bushing 20 inside the stator body 10, the outer surface of the protective sleeve 30 fixedly connected to the stator body 10, and a second spiral structure provided on the inner surface of the protective sleeve 30.

[0040] The spiral shape of the first spiral structure is the same as that of the second spiral structure.

[0041] The sheath 30 of this invention features a second helical structure, ensuring that the sheath 30 and the rotor also have an N+1 and N-head helical fit, guaranteeing a downward cavity for the drilling fluid and improving the downward efficiency of the drilling fluid. Simultaneously, the design of the second helical structure allows for a smaller thickness difference between the sheath 30 and the rubber bushing 20, providing better protection for the rubber bushing 20. If the sheath 30 were the inner ring structure of the prior art, its radial thickness could not exceed the minimum radial thickness of the rubber bushing 20 to accommodate the rotor; that is, the radial thickness of the sheath 30 could not exceed the trough of the first helical structure of the rubber bushing 20. In this case, the upper part of the peak and the transition surface of the first helical structure of the rubber bushing 20 would directly contact the drilling fluid, and the lower part would directly collide with the rotor, neither receiving protection from the sheath 30. This situation is more pronounced when the thickness difference between the peak and trough of the first helical structure of the rubber bushing 20 is relatively large.

[0042] It should be noted that the N+1 head and N-head helical fit should be understood as follows: the number of helical heads in the first helical structure of the rubber bushing 20 and the second helical structure of the sheath 30 are both N+1, and the number of heads in the helical structure on the outer surface of the rotor is N. Thus, after the rubber bushing 20 and sheath 30 are fitted with the rotor, a cavity is formed, providing a channel for the drilling fluid to flow downwards. Specifically, for example, the number of heads in both the first and second helical structures is 8, and the number of heads in the helical structure of the rotor is 7. Simultaneously, the outer diameter of the rotor and the inner diameter of the rubber bushing 20 are interference-fitted to achieve a line seal.

[0043] There are no restrictions on the connection method between the sheath 30 and the rubber bushing 20, so the sheath 30 and the rubber bushing 20 can be connected by contact or by a fixed connection. As long as the sheath 30 is set at both ends of the rubber bushing 20, the flushing pressure of the drilling fluid and the impact of the rotor will act on the sheath 30 first, which can not only better protect the rubber bushing 20, but also avoid the rubber bushing 20 from being frequently squeezed and losing its adhesion to the stator body 10; furthermore, the rubber bushing 20 will not be subjected to extreme compression, and its compression heat generation will also be reduced, further avoiding the adhesion failure between the rubber bushing 20 and the stator body 10.

[0044] The present invention does not impose limitations on the radial thickness (i.e., the wall thickness of the sheath 30) and the radial thickness (i.e., the wall thickness of the rubber bushing 20). However, in order to ensure a smooth transition between the sheath 30 and the rubber bushing 20, reduce the degree of deformation of the rubber bushing 20 under pressure, and provide better protection for the rubber bushing 20, in some embodiments, the axial length of the sheath 30 is 50mm to 150mm, and the difference between the radial thickness of the sheath 30 and the radial thickness of the rubber bushing 20 is -0.2mm to 0mm. Since the rubber bushing 20 has a first helical structure and the sheath 30 has a second helical structure, the wall thickness of both the rubber bushing 20 and the sheath 30 has crests, troughs, and connecting sections between crests and troughs. Therefore, the difference between the radial thickness of the sheath 30 and the radial thickness of the rubber bushing 20 is -0.2mm to 0mm. This should be understood as the difference between the radial thickness at the crest of the rubber bushing 20 and the radial thickness at the crest of the sheath 30, the difference between the radial thickness at the trough of the rubber bushing 20 and the radial thickness at the trough of the sheath 30, and the difference between the radial thickness at the connecting section between the crests and troughs of the rubber bushing 20 and the radial thickness at the connecting section between the crests and troughs of the sheath 30.

[0045] To ensure a seamless connection between the sheath 30 and the rubber bushing 20, and to avoid stress concentration and premature seal failure caused by the protruding edges of the rubber bushing 20, in some embodiments, the ends of the inner surface of the rubber bushing 20 are chamfered. Preferably, the chamfer is greater than 0° and less than or equal to 45°.

[0046] The present invention does not limit the materials used for the rubber bushing 20 and the sheath 30. In some embodiments, the sheath 30 is made of a temperature-resistant, wear-resistant, and high-elastic-modulus material; wherein the maximum temperature resistance of the temperature-resistant, wear-resistant, and high-elastic-modulus material is 250℃, the coefficient of friction ranges from 0.1 to 0.4, and the elastic modulus ranges from 3GPa to 150GPa. This has the advantage of improving the protective capability of the sheath 30 and extending its service life.

[0047] In some embodiments, the temperature-resistant, wear-resistant, and high-elasticity modulus material includes polyimide, polyetheretherketone, or a metal ring.

[0048] In some embodiments, the rubber bushing 20 is made of nitrile rubber, hydrogenated nitrile rubber, or fluororubber.

[0049] To further improve the wear resistance, temperature resistance, and corrosion resistance of the sheath 30, in some embodiments, the surface of the sheath 30 is treated with a spraying process, which involves spraying a LI NE-X coating (Lex protective coating, a superelastic material mainly composed of polyurethane and polyurea elastomers), a PTFE coating (polytetrafluoroethylene coating), or a ceramic coating.

[0050] The second aspect of this embodiment provides a screw drill motor, including a rotor and the aforementioned screw drill motor stator, wherein the outer surface of the rotor is provided with a helical surface, and the rotor is inserted into the screw drill motor stator.

[0051] The third aspect of this embodiment provides a method for forming a stator of a screw drill motor, the method comprising the following steps:

[0052] The pre-formed stator body 10, rubber bushing 20 and sheath 30 are obtained;

[0053] The rubber bushing 20 and the sheath 30 are fixed inside the stator body 10 to obtain the screw drill motor stator as described above.

[0054] In some embodiments, the preforming process of the sheath 30 includes:

[0055] Preparations include selecting the machine tool, preparing the cutting tool, preparing the bar stock blank with a 30mm sheath, and completing the relative position and fixing of the cutting tool and the blank.

[0056] The programming input involves writing the program and parameters for machining the sheath 30 based on the inner cavity dimensions of the stator body 10 and the helical shape of the first helical structure of the rubber bushing 20, and then inputting them into the machine tool system.

[0057] The spiral surface is machined by roughing, semi-finishing and finishing to complete the second spiral structure of the sheath 30.

[0058] The outer diameter is machined to complete the outer diameter dimension of the sheath, surface roughening and activation processing.

[0059] In some embodiments, the sheath 30 is connected to the stator body 10 by means of adhesive or mechanical fastening.

[0060] The adhesives include epoxy resin adhesives, high-strength structural adhesives, instant adhesives, or anaerobic adhesives. The specific steps for connecting the sheath 30 to the stator body 10 using adhesives are: surface treatment, adhesive preparation, adhesive application, assembly, and curing.

[0061] To further improve the safety of the connection between the sheath 30 and the stator body 10, the sheath 30 and the stator body 10 are interference-fitted in addition to being fixed by adhesive or mechanical means.

[0062] Among them, mechanical fixing methods include outer circle anchoring, tenon and mortise fixing, nesting fixing, slot fixing or expansion bolt fixing.

[0063] In some embodiments, when the sheath 30 is connected to the stator body 10 by an adhesive, the sheath 30 and the stator body 10 are polished, sulfonated, plasma-treated, or threaded before the adhesive is applied.

[0064] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0065] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" 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, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of multiple components or the interaction between multiple components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0066] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A stator for a screw drill motor, comprising a stator body (10), wherein a rubber bushing (20) is installed on the inner wall of the stator body (10), and the inner surface of the rubber bushing (20) is provided with a first helical structure, characterized in that, Inside the stator body (10), both ends of the rubber bushing (20) are provided with sheaths (30), the outer surface of the sheaths (30) is fixedly connected to the stator body (10), and the inner surface of the sheaths (30) is provided with a second spiral structure. The spiral shape of the first spiral structure is the same as that of the second spiral structure.

2. The stator of a screw drill motor according to claim 1, characterized in that, The axial length of the sheath (30) is 50mm to 150mm, and the difference between the radial thickness of the sheath (30) and the radial thickness of the rubber bushing (20) is -0.2mm to 0mm.

3. The stator of a screw drill motor according to claim 2, characterized in that, The inner surface of the rubber bushing (20) is chamfered at the end.

4. The stator of a screw drill motor according to claim 1, characterized in that, The sheath (30) is made of a high-temperature resistant, wear-resistant, and high-elasticity modulus material; Among them, the highest temperature resistance of the high temperature resistance and wear resistance material with high elastic modulus is 250℃, the coefficient of friction ranges from 0.1 to 0.4, and the elastic modulus ranges from 3GPa to 150GPa.

5. The stator of a screw drill motor according to claim 4, characterized in that, The temperature-resistant, wear-resistant, and high-elasticity modulus material includes polyimide, polyetheretherketone, or metal rings.

6. The stator of a screw drill motor according to claim 1, characterized in that, The surface of the sheath (30) has been sprayed.

7. A screw drill motor, characterized in that, It includes a rotor and a stator of a screw drill motor as described in any one of claims 1-6, wherein the outer surface of the rotor is provided with a helical surface, and the rotor is inserted into the stator of the screw drill motor.

8. A method for forming a stator of a screw drill motor, characterized in that, The molding method includes the following steps: The preformed stator body (10), rubber bushing (20) and sheath (30) are obtained; The rubber bushing (20) and the sheath (30) are fixed inside the stator body (10) to obtain the stator of the screw drill motor as described in any one of claims 1-6.

9. A method for forming a stator of a screw drill motor according to claim 8, characterized in that, The preforming process of the sheath (30) includes: Preparation work: Select machine tool, prepare cutting tool, prepare bar blank with sheath (30), and complete the relative position and fixation of cutting tool and blank; The programming input is based on the inner cavity dimensions of the stator body (10) and the helical line shape of the first helical structure of the rubber bushing (20). The program and parameters for machining the sheath (30) are written and input into the machine tool system. The spiral surface is machined by roughing, semi-finishing and finishing to complete the machining of the second spiral structure of the sheath (30); The outer diameter is machined to complete the outer diameter dimensions, surface roughening and activation of the sheath (30).

10. A method for forming a stator of a screw drill motor according to claim 8, characterized in that, The sheath (30) is connected to the stator body (10) by means of adhesive or mechanical fixation.

Images