Screw drill motor stator, screw drill motor and forming method

Abstract

The invention belongs to screw drilling tools in the field of petroleum and natural gas well drilling, and particularly relates to a screw drilling tool motor stator, a screw drilling tool and a forming method.The screw drilling tool motor stator comprises a shell and rubber arranged on the inner wall of the shell, the inner wall and the outer wall of the shell are each of a spiral structure, the inner wall of the rubber is of a spiral structure, and the outer wall of the shell is of a spiral structure. An inner cavity of the shell is axially and gradually changed; an inner cavity of the rubber is provided with an axial gradual change in the same direction as the inner cavity of the shell; and the gradual change angle of the axial gradual change of the shell is equal to the gradual change angle of the axial gradual change of the rubber. The shell and the rubber are axially gradually changed, when high-pressure drilling fluid enters the inner cavity of the shell, the rubber can be prevented from being scoured by the high-pressure drilling fluid, impact damage of the rotor to the rubber is buffered, torque and speed are increased, and the sand-carrying capacity is improved, and the service life of the rubber is prolonged.

Description

Technical Field

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

[0002] Screw drills are volumetric downhole power drills that use drilling fluid as power, converting fluid pressure energy into mechanical energy. In recent years, with the growth of global oil and natural gas demand, the market demand for screw drills has also been gradually increasing. As drilling technology continues to improve, higher requirements are being placed on the performance and quality of screw drills. To meet market demands, especially the needs of unconventional oil and gas fields and geothermal resource extraction, screw drill manufacturers are constantly innovating and upgrading their products, continuously optimizing efficiency, energy saving, and temperature resistance to improve product performance and reliability.

[0003] Among them, equal-wall-thickness screws have the characteristics of high output power, long service life, and strong adaptability to complex working conditions, so equal-wall-thickness screws are a key research and development direction. For example, patent CN105356646B designed an equal-wall-thickness metal bushing screw motor, proposing a double equal-wall-thickness structure of metal and rubber to achieve the purpose of equal wall-thickness of the rubber layer in contact with the rotor; patent application CN106014199A disclosed a segmented equal-wall-thickness screw drill stator, which completes the series connection of equal-wall-thickness stators by introducing pins, achieving the purpose of short machining of long stators; patent CN102773549B disclosed an equal-wall-thickness screw drill stator, which achieves equal-wall-thickness rubber forming through broaching; patent CN202260656U disclosed an internally and externally equal-wall-thickness rear screw motor, which changed the shape of the inner and outer walls of the stator housing, making the stator rubber layer thin and uniform, and overcoming the shortcomings of conventional screw drill stator technology.

[0004] However, the aforementioned existing technologies have drawbacks in use, such as low sand-carrying capacity and short rubber lifespan.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] 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 housing and rubber of the present invention have an axial gradient, which can prevent the rubber from being washed by the high-pressure drilling fluid when the high-pressure drilling fluid enters the inner cavity of the housing, buffer the rotor from impacting and damaging the rubber, and increase torque and speed, thus improving the sand carrying capacity and extending the service life of the rubber.

[0007] This invention includes the following technical solutions:

[0008] The first aspect of the present invention provides a stator for a screw drill motor, comprising a housing and a rubber disposed on the inner wall of the housing, wherein the inner and outer walls of the housing are both helical structures, the inner wall of the rubber is helical, and the inner cavity of the housing has an axial gradient; the inner cavity of the rubber has an axial gradient in the same direction as the inner cavity of the housing; the gradient angle of the axial gradient of the housing is equal to the gradient angle of the axial gradient of the rubber.

[0009] Furthermore, the gradient angle of the axial gradient of the housing is 1° to 10°.

[0010] Furthermore, the wall thickness of the rubber is 3mm to 10mm; and / or the wall thickness of the shell is 5mm to 20mm.

[0011] Furthermore, the inner and outer walls of the housing are of equal thickness; and / or the inner and outer walls of the rubber are of equal thickness.

[0012] Furthermore, the housing includes a first connecting section, a mating section for engaging with the rotor, and a second connecting section connected in sequence, with the rubber located in the mating section.

[0013] Furthermore, the cross-section of the mating section is shaped like a plum blossom.

[0014] Furthermore, the first connecting segment is provided with a first internal thread; and / or the second connecting segment is provided with a second internal thread.

[0015] A second aspect of the present invention provides a screw drill motor, including the screw drill motor stator and rotor described above, wherein the rotor is disposed in the inner cavity of the housing, and the rotor includes a working section that mates with rubber, the outer wall of the working section having a helical structure.

[0016] Furthermore, the cross-section of the working section is shaped like a plum blossom.

[0017] A third aspect of the present invention provides a method for forming a stator of a screw drill motor, the forming method comprising the following steps:

[0018] A first structure with a plum blossom shape is obtained by processing a frustum-shaped metal tube using a first mold.

[0019] The first structure is spirally twisted using a spiral twisting machine to obtain a second structure with a spiral structure.

[0020] The third structure is obtained by rolling the spiral structure using a rolling mill;

[0021] Rubber is injected into the inner wall of the third structure through the cooperation of a glue injection machine and a second mold to obtain the stator of the screw drill motor as described above.

[0022] The first mold includes an inner mold and an outer mold. The outer wall of the cross-section of the inner mold is shaped like a plum blossom, and the inner wall of the cross-section of the outer mold is shaped like a plum blossom.

[0023] The outer wall of the second mold has a spiral structure and has an axial gradient in the same direction as the inner cavity of the shell.

[0024] By adopting the above technical solution, the present invention has the following advantages:

[0025] 1. The shell and rubber of the present invention have an axial gradient, which can prevent the rubber from being washed by the high-pressure drilling fluid when the high-pressure drilling fluid enters the inner cavity of the shell, buffer the rotor from impacting and damaging the rubber, and increase torque and speed, thus improving the sand carrying capacity and the service life of the rubber.

[0026] 2. The axial gradient of this invention can balance the fluid (high-pressure drilling fluid) pressure, reduce rotor vibration during operation, and improve the stability and reliability of motor operation.

[0027] 3. The present invention sets the rubber wall thickness to a certain degree, which has higher uniformity and better durability, and improves the service life of the rubber.

[0028] 4. The shell and rubber of the present invention have equal wall thickness inside and out, which ensures that the rubber thickness is consistent throughout the stator, avoids stress concentration caused by uneven thickness, and thus reduces the risk of local wear; the uniform rubber layer can provide better wear resistance and anti-aging performance, and extend the service life of the motor; the equal wall thickness design can ensure a good seal between the rubber and the metal shell, prevent drilling fluid leakage, and improve the working efficiency of the motor.

[0029] 5. The combination of the shell and rubber of the present invention with equal wall thickness and axial gradient can optimize hydrodynamic performance, reduce the impact of fluid on the rubber layer, improve sand carrying efficiency, and enhance the stability and reliability of the motor; the equal wall thickness design can reduce material waste, lower production costs, and improve the market competitiveness of the product.

[0030] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0031] 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.

[0032] Figure 1 This is a schematic diagram of the structure of a screw drill motor stator in an embodiment of the present invention. Figure 1 ;

[0033] Figure 2 This is a schematic diagram of the structure of a screw drill motor stator in an embodiment of the present invention. Figure 2 ;

[0034] Figure 3 This is a cross-sectional schematic diagram of the stator mating section of a screw drill motor according to an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of the structure of the frustum-shaped metal tube in an embodiment of the present invention;

[0036] Figure 5 This is a schematic diagram of the structure of the second mold in an embodiment of the present invention;

[0037] In the figure: 10-shell, 11-first connecting section, 12-second connecting section, 13-fitting section, 20-rubber, 30-frustum metal tube, 40-second mold. Detailed Implementation

[0038] 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.

[0039] 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.

[0040] The first aspect of this embodiment provides a stator for a screw drill motor, such as... Figure 1As shown, the device includes a housing 10 and a rubber 20 disposed on the inner wall of the housing 10. The inner and outer walls of the housing 10 are both helical structures, and the inner wall of the rubber 20 is also helical. The inner cavity of the housing 10 has an axial gradient; the inner cavity of the rubber 20 has an axial gradient in the same direction as the inner cavity of the housing 10; the gradient angle of the axial gradient of the housing 10 is equal to the gradient angle of the axial gradient of the rubber 20.

[0041] The housing 10 is a ring-shaped structure, so it has a cavity that extends through both ends, which is the inner cavity; similarly, the rubber 20 set on the inner wall of the housing 10 also has an inner cavity that extends through both ends; this inner cavity needs to allow drilling fluid to pass through during operation.

[0042] Axial gradient should be understood as follows: along the axial direction of the housing 10, the size of the radial cross section of the inner cavity of the housing 10 gradually changes, and the size of the radial cross section of the inner cavity of the rubber 20 gradually changes. That is, the inner wall of the housing 10 is inclined in the axial direction, and the inner wall of the rubber 20 is inclined in the axial direction.

[0043] The stator of the screw drill motor of this invention, during use, can prevent the rubber 20 from being eroded by high-pressure drilling fluid, buffer the impact damage to the rubber 20 caused by the rotor, and increase torque and speed, thus improving the sand-carrying capacity and extending the service life of the rubber 20. Specifically, when the high-pressure drilling fluid enters the flow channel, the larger flow channel area buffers the erosion pressure of the high-pressure drilling fluid on the rubber 20, reducing the pressure of the high-pressure drilling fluid. The resistance of the rubber 20 to rotor damage describes the rubber 20 at the lower end of the stator. Due to the eccentric rotation of the rotor and the reaction force of the formation, the rotor has a large impact on the rubber 20. Through a gradual design, the rubber 20 at the end with the smaller inner diameter has a certain interference fit with the rotor, reducing the rotor's eccentricity and thus weakening the damage to the rubber 20. After the drilling fluid enters the annulus within the casing 10, the axially tapered shape of the annulus reduces the flow area, increasing the drilling pressure and thus accelerating the rotor speed. This torque-increasing speed refers to the increased output torque of the motor and the increased rotor speed. During the upward drilling process, the increased drilling pressure and torque allow for faster rotation speed and improved drilling efficiency. Propellant carrying capacity is the ability to carry particulate matter such as cuttings and sand. The axially tapered shape of the casing 10 means that as the drilling fluid returns to the surface from bottom to top, the fluid cross-sectional area gradually decreases, increasing the flow velocity and thus enhancing proppant carrying capacity.

[0044] If the gradient angle of the axial gradient is too large, it will cause uneven distribution of the pressure on the rubber 20 (i.e., the pressure exerted on the rubber 20 by the drilling fluid and the rotor), resulting in a reduced service life of the rubber 20; however, if the gradient angle is too small, it will reduce the sand-carrying capacity of the drilling fluid; therefore, in some embodiments, such as Figure 2As shown, the axial gradient angle of the housing 10 is 1° to 10°, where α represents the gradient angle. This gradient angle not only improves the uniformity of pressure resistance of the rubber 20 but also provides good sand-carrying capacity.

[0045] If the wall thickness of rubber 20 is less than 3mm, the bonding strength between rubber 20 and shell 10 and the wear resistance of rubber 20 will decrease, resulting in a shorter service life of rubber 20. Moreover, if shell 10 has a slender structure, if rubber 20 is too thin, the processing difficulty and the difficulty in controlling eccentricity will increase, resulting in a low product qualification rate. If it is greater than 10mm, rubber 20 will generate too much heat, resulting in excessive heat accumulation and making it more prone to delamination. At the same time, it is also detrimental to cost control, and the reduced rigidity will also reduce fluid flow efficiency. Therefore, in some embodiments, the wall thickness of rubber 20 is 3mm to 10mm; a wall thickness of 3mm to 10mm for rubber 20 also has the advantage of ensuring sufficient wear resistance and impact resistance.

[0046] The rigidity and pressure resistance provided by an excessively thin shell 10 structure cannot enable normal drilling, while an excessively thick shell 10 will increase weight and manufacturing costs; therefore, in some embodiments, the wall thickness of the shell 10 is 5 mm to 20 mm.

[0047] In some embodiments, the housing 10 has equal wall thickness inside and out; and / or the rubber 20 has equal wall thickness inside and out.

[0048] Equal wall thickness inside and outside should be understood as follows: the radial distance between the outer wall and the inner wall of the housing 10 at any position is equal, and the radial distance between the outer wall and the inner wall of the rubber 20 at any position is equal. It should be noted that, based on the equal wall thickness inside and outside of the housing 10 and the rubber 20, the housing 10 and the rubber 20 also have an axial gradient, so the outer wall of the housing 10 and the rubber 20 must also have an axial gradient.

[0049] In some embodiments, such as Figure 1 As shown, the housing 10 includes a first connecting section 11, a mating section 13 for cooperating with the rotor, and a second connecting section 12 connected in sequence, with the rubber 20 located in the mating section 13.

[0050] In some embodiments, such as Figure 3 As shown, the cross-section of the mating section 13 is shaped like a plum blossom.

[0051] In some embodiments, the first connecting segment 11 is provided with a first internal thread; and / or the second connecting segment 12 is provided with a second internal thread. The first and second internal threads are used for connection with other structures described above (other structures of screw drills).

[0052] The second aspect of this embodiment provides a screw drill motor, including the screw drill motor stator and rotor as described above. The rotor is disposed in the inner cavity of the housing 10. The rotor includes a working section that mates with rubber 20, and the outer wall of the working section has a helical structure.

[0053] In some embodiments, the cross-section of the working section is quincunx-shaped, for mating with the quincunx-shaped mating section 13 of the housing 10.

[0054] The third aspect of this embodiment provides a method for forming a stator of a screw drill motor, the forming method comprising the following steps:

[0055] Process frustum-shaped metal tubes (such as those made using the first mold) Figure 4 As shown, a first structure with a plum blossom shape is obtained; the first mold includes an inner mold and an outer mold, the outer wall of the cross-section of the inner mold is plum blossom shaped, and the inner wall of the cross-section of the outer mold is plum blossom shaped; specifically, the inner mold is set inside the frustum-shaped metal tube, and the outer mold is set outside the frustum-shaped metal tube, and the frustum-shaped metal tube is processed into a first structure with a plum blossom shape by the cooperation of the inner mold and the outer mold.

[0056] The first structure is spirally twisted by a spiral twisting machine to obtain a second structure with a spiral structure. Specifically, the spiral twisting machine applies a torsional force to make the first structure form a uniform spiral structure along the axial direction. This process ensures the consistency of the spiral angle and spacing by controlling the twisting speed and force. It should be noted that, for those skilled in the art, the twisting speed and force are set according to the actual situation such as the spiral pitch and the size and length of the shell 10.

[0057] The third structure is obtained by rolling the spiral structure using a rolling mill; more specifically, the steps may include the following:

[0058] Pretreatment: The second structure is cleaned and preheated to ensure that the surface is free of impurities and oil.

[0059] Roller preparation: The roller is composed of multiple sets of rollers, which are installed inside the roller and a third mold that matches the outer diameter of the second structure is provided on the outside; a certain gap is left between the roller and the mold to ensure that the roller can rotate freely and apply pressure;

[0060] Initial positioning: Place the second structure at the inlet of the rolling mill, ensuring it is aligned with the rollers and the third mold;

[0061] Roller movement: Start the rolling mill, the rollers begin to rotate and gradually apply pressure to the interior of the second structure; the speed and pressure of the rollers need to be controlled according to design requirements to ensure the consistency of the helical angle and spacing; for those skilled in the art, the speed and pressure of the rollers are set accordingly based on the actual situation such as the pitch of the helical structure;

[0062] Third mold support: The outer mold of the third mold provides support for the outer wall of the second structure to prevent it from deforming during the rolling process. The design of the third mold needs to match the movement path of the roller to ensure that the second structure maintains a stable shape during the rolling process.

[0063] Multi-stage rolling: The rolling process can be divided into multiple stages. The pressure and speed of the rollers in each stage can be gradually adjusted to optimize the formation of the spiral structure. Multi-stage rolling can ensure that the spiral angle and spacing of the metal tube remain consistent at different positions.

[0064] Rubber 20 is injected into the inner wall of the third structure through the cooperation of a glue injection machine and a second mold 40 to obtain the stator of the screw drill motor described above; more specifically, it may include the following steps:

[0065] Pretreatment: The inner wall of the third structure is cleaned and pretreated to ensure it is clean and free of oil; at the same time, an adhesive is applied to the inner wall of the third structure.

[0066] Injection: The rubber 20 material is heated to a molten state. The second mold 40 is set in the inner cavity of the third structure. The rubber 20 is injected into the gap between the third structure and the second mold 40 using a high-pressure injection machine, so that the rubber 20 is fixed on the inner wall of the third structure. During the injection process, it is necessary to control the temperature and pressure to ensure that the rubber 20 is uniform. For those skilled in the art, the temperature and pressure are set according to the actual situation.

[0067] Curing: The third structure after adhesive injection is placed in a curing oven and cured according to the predetermined temperature profile; during the curing process, time and temperature need to be strictly controlled to ensure that the 20 rubber layers are cured uniformly and tightly bonded to the third structure;

[0068] like Figure 5 The outer wall of the second mold 40 shown is a spiral structure, and the outer wall of the second mold 40 has an axial gradient in the same direction as the inner cavity of the housing 10.

[0069] 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.

[0070] 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.

[0071] 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 housing (10) and a rubber (20) disposed on the inner wall of the housing (10), wherein the inner and outer walls of the housing (10) are both helical structures, and the inner wall of the rubber (20) is helical, characterized in that, The inner cavity of the housing (10) has an axial gradient; the inner cavity of the rubber (20) has an axial gradient in the same direction as the inner cavity of the housing (10); the gradient angle of the axial gradient of the housing (10) is equal to the gradient angle of the axial gradient of the rubber (20).

2. The stator of a screw drill motor according to claim 1, characterized in that, The axial gradient angle of the housing (10) is 1° to 10°.

3. A stator for a screw drill motor according to claim 1 or 2, characterized in that, The wall thickness of the rubber (20) is 3mm to 10mm; and / or the wall thickness of the shell (10) is 5mm to 20mm.

4. A stator for a screw drill motor according to claim 1 or 2, characterized in that, The shell (10) has equal wall thickness inside and out; and / or the rubber (20) has equal wall thickness inside and out.

5. The stator of a screw drill motor according to claim 1, characterized in that, The housing (10) includes a first connecting section (11), a mating section (13) for cooperating with the rotor, and a second connecting section (12) connected in sequence, with the rubber (20) located in the mating section (13).

6. The stator of a screw drill motor according to claim 5, characterized in that, The cross-section of the mating section (13) is plum blossom shaped.

7. A stator for a screw drill motor according to claim 5 or 6, characterized in that, The first connecting segment (11) is provided with a first internal thread; and / or the second connecting segment (12) is provided with a second internal thread.

8. A screw drill motor, characterized in that, Includes a stator and rotor of a screw drill motor as described in any one of claims 1-7, wherein the rotor is disposed in the inner cavity of the housing (10), and the rotor includes a working section that mates with rubber (20), the outer wall of which has a helical structure.

9. A screw drill motor according to claim 8, characterized in that, The cross-section of the working section is shaped like a plum blossom.

10. A method for forming the stator of a screw drill motor, characterized in that, The molding method includes the following steps: A first structure with a plum blossom shape is obtained by processing a frustum-shaped metal tube using a first mold. The first structure is spirally twisted using a spiral twisting machine to obtain a second structure with a spiral structure. The third structure is obtained by rolling the spiral structure using a rolling mill; Rubber (20) is injected into the inner wall of the third structure by the cooperation of a glue injection machine and a second mold (40) to obtain the stator of the screw drill motor as described in any one of claims 1-7; The first mold includes an inner mold and an outer mold. The outer wall of the cross-section of the inner mold is shaped like a plum blossom, and the inner wall of the cross-section of the outer mold is shaped like a plum blossom. The outer wall of the second mold (40) is a spiral structure, and the outer wall of the second mold (40) has an axial gradient in the same direction as the inner cavity of the shell (10).

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