Flexible screw drilling tool for ultra-short radius well drilling

Abstract

The invention discloses a flexible screw drilling tool for ultra-short radius well drilling. The technical problems that an ultra-short radius flexible drilling tool is low in well drilling torque transmission efficiency, the well drilling track is difficult to adjust, and a conventional screw drilling tool is high in rigidity and is difficult to descend into an ultra-short radius well are solved. The device comprises an upper connector, a power part, a lower connector, a transmission short section and a drill bit, the power part comprises a stator shell, a stator bush and a screw rotor, the stator shell can be bent, the screw rotor is in conjugate fit with the stator bush, the stator bush and the screw rotor are made of bendable materials, a threaded flow channel is formed in the inner side wall of the stator bush, and the threaded flow channel is communicated with the lower connector. The threaded flow channel is matched with threads on the screw rotor, and when drilling fluid flows through the threaded flow channel, the screw rotor does planetary motion in the circumferential direction of the stator bush under the drilling fluid pressure difference and the conjugate action of the stator bush and the screw rotor, and the drill bit is made to rotate through the transmission short section. The torque transmission efficiency can be improved, and the drilling track can be adjusted.

Description

Technical Field

[0001] The invention belongs to the technical field of oil well drilling, and in particular relates to a flexible screw drilling tool for ultra-short radius drilling. Background Art

[0002] At present, as the development of oil and gas fields gradually enters the middle and late stages, the development of low-permeability oil and gas reservoirs, residual oil between wells, thin oil layers near the wellbore area, and medium-low permeability oil reservoirs is an important direction for the replacement of offshore oilfield production capacity. Ultra-short radius drilling and completion technology is one of the important measures to effectively tap the potential of low-permeability oil and gas reservoirs, thin oil reservoirs, and residual oil near the wellbore area. Compared with conventional horizontal wells, ultra-short radius horizontal wells have shorter inclination sections, and have the technical advantages of short target front distance, no loss of oil layers, application to new wells and old wells, multiple branches can be drilled in one well, high potential tapping, short construction time, and low cost.

[0003] The ultra-short radius drilling technology (MUR) based on flexible screw drill bits in the related technology is a drilling tool composed of multiple connected flexible short sections with a curvature radius range of 3-5m. The window opening, deflection, and horizontal section drilling are all completed in the oil layer section, and the drilling is extended along the oil layer. However, if the deflection section is deep, the length of the drill bit will be too long, and there will be serious support pressure. The torque cannot be effectively transmitted to the drill bit, which seriously affects the extension distance of the horizontal section of the wellbore. In addition, since conventional screw drill bits are difficult to lower into the deflection section of ultra-short radius horizontal wells, it is impossible to control and adjust the trajectory of the horizontal section. Once the oil layer is drilled out, the operation can only be terminated, which needs to be improved. Summary of the invention

[0004] In order to solve all or part of the above problems, the purpose of the present invention is to provide a flexible screw drill for ultra-short radius drilling, which can improve the torque transmission efficiency, extend the horizontal section extension distance, and adjust the drilling trajectory.

[0005] The present invention provides a flexible screw drill for ultra-short radius drilling, comprising an upper joint, a power unit, a lower joint, a transmission short section and a drill bit connected in sequence from top to bottom, wherein the power unit comprises:

[0006] A stator housing, the top end of which is connected to the upper joint, the bottom end of which is connected to the lower joint, and the stator housing is bendable;

[0007] A stator bushing, fixed to the inner wall of the stator housing;

[0008] A screw rotor is disposed in the stator bushing and is conjugately matched with the stator bushing, and the bottom end of the screw rotor is connected to the transmission short section;

[0009] The stator bushing and the screw rotor are respectively made of flexible materials. The inner side wall of the stator bushing is provided with a threaded flow channel, and the threaded flow channel cooperates with the thread on the screw rotor. When the drilling fluid flows through the threaded flow channel, under the drilling fluid pressure difference and the conjugate action of the stator bushing and the screw rotor, the screw rotor performs planetary motion along the circumference of the stator bushing, and converts the planetary motion into axial motion through the transmission short section and transmits it to the drill bit, so that the drill bit rotates along its own axis.

[0010] Optionally, the stator bushing is made of rubber material, and the stator bushing is fixed to the inner wall of the stator housing by vulcanization.

[0011] Optionally, the stator housing is composed of a plurality of universal joints connected in series, and the universal joint located at the top is connected to the upper joint, and the universal joint located at the bottom is connected to the lower joint.

[0012] Optionally, each of the universal joints comprises:

[0013] A universal sleeve, fixedly mounted on the stator sleeve;

[0014] A support sleeve, a fixed sleeve arranged on the stator sleeve and located below the universal sleeve;

[0015] A support shaft, the top end of which is located in the universal sleeve and the bottom end of which is threadedly connected to the support sleeve;

[0016] A universal ball, integrally formed and connected to the top end of the support shaft, and forming a universal rotation fit with the universal sleeve;

[0017] The clearance hole penetrates the support shaft and the universal ball, and the stator bushing passes through the clearance hole and is fixedly connected with the support shaft and the universal ball.

[0018] Optionally, each of the universal sleeves is threadedly connected with a limited rotation pin, and each of the universal balls is provided with a limited rotation groove, the limited rotation pin is located in the corresponding limited rotation groove, and a limited rotation gap is formed between the outer wall of the limited rotation pin and the inner wall of the corresponding limited rotation groove to limit the rotation angle of the universal ball relative to the universal sleeve.

[0019] Optionally, a limiting ring is integrally formed at the lower end of each universal sleeve, and the limiting ring abuts against the spherical surface at the lower end of the corresponding universal ball.

[0020] Optionally, the inner side wall of each of the limiting rings is respectively provided with a first guiding arc surface, and the first guiding arc surface is tightly matched with the lower end spherical surface of the corresponding universal ball.

[0021] Optionally, the outer side walls of the upper joint and each of the support sleeves are respectively provided with external threads, and the inner side walls of each of the universal sleeves are respectively provided with internal threads, and the external threads match the internal threads. When the universal sleeve is threadedly connected to the upper joint or the corresponding support sleeve, the bottom end of the upper joint or the universal sleeve abuts against the upper spherical surface of the corresponding universal ball.

[0022] Optionally, the upper joint and the bottom end of each universal sleeve are respectively provided with a second guide arc surface, and the second guide arc surface is tightly matched with the upper end spherical surface of the corresponding universal ball.

[0023] Optionally, a sealing ring is fixedly embedded on each of the second guide arc surfaces, and the sealing ring is in tight contact with the upper spherical surface of the corresponding universal ball.

[0024] It can be seen from the above technical solution that the flexible screw drilling tool for ultra-short radius drilling provided by the present invention has the following advantages:

[0025] The flexible screw drill uses drilling fluid as the driving medium. When the drilling fluid flows through the threaded flow channel, under the drilling fluid pressure difference and the conjugate action of the stator bushing and the screw rotor, the screw rotor can perform planetary motion along the circumference of the stator bushing, and convert the planetary motion into axial motion through the transmission short section and transmit it to the drill bit, so that the drill bit rotates along its own axis. This design can shorten the distance between the power source and the drill bit, thereby improving the torque transmission efficiency, ensuring the speed of the drill bit, and improving the operation time efficiency. At the same time, since the screw rotor, stator bushing and stator housing can be bent, and the length of the entire screw drill is reduced, it can not only effectively reduce the radius of curvature and realize ultra-short radius drilling, but also extend the horizontal section extension distance, and realize the adjustment of the drilling trajectory. In addition, during the horizontal drilling of the screw drill, when the measurement while drilling signal measures a large change in the well inclination angle, the rotary table drive can be stopped to adjust the tool face, and the drilling pressure and speed can be adjusted, and sliding drilling is adopted to control the wellbore trajectory within the reservoir.

[0026] Other features and advantages of the present invention will be set forth in the description which follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

[0028] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present invention;

[0029] Figure 2 is a cross-sectional view of an embodiment of the present invention;

[0030] Figure 3 Schematic diagram of the structure of the screw rotor in the embodiment of the present invention;

[0031] Figure 4 is a cross-sectional view of a stator bushing in an embodiment of the present invention;

[0032] Figure 5 is a cross-sectional view of a power unit in an embodiment of the present invention;

[0033] Figure 6 2 is a cross-sectional view of a universal joint in an embodiment of the present invention.

[0034] Description of reference numerals:

[0035] 1. Upper joint; 2. Power unit; 21. Stator housing; 22. Stator bushing; 23. Screw rotor; 24. Threaded flow channel; 3. Lower joint; 4. Transmission short section; 5. Drill bit; 6. Universal joint; 61. Universal sleeve; 62. Support sleeve; 63. Support shaft; 64. Universal ball; 65. Clearance hole; 7. Limiting pin; 8. Limiting groove; 9. Limiting gap; 10. Limiting ring; 11. First guide arc surface; 12. External thread; 13. Internal thread; 14. Second guide arc surface; 15. Sealing ring. DETAILED DESCRIPTION

[0036] To make the purpose, technical solution and advantages of the present invention more clear, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other arbitrarily without conflict.

[0037] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 The embodiment of the present invention is shown in the figure, which discloses a flexible screw drill for ultra-short radius drilling, including an upper joint 1, a power unit 2, a lower joint 3, a transmission short section 4 and a drill bit 5 connected in sequence from top to bottom, the power unit 2 includes a stator housing 21, a stator bushing 22 and a screw rotor 23, the top end of the stator housing 21 is connected to the upper joint 1, the bottom end is connected to the lower joint 3, and the stator housing 21 can be bent. The stator bushing 22 is fixed on the inner side wall of the stator housing 21, the screw rotor 23 is arranged in the stator bushing 22, and is conjugately matched with the stator bushing 22, and the bottom end of the screw rotor 23 is connected to the transmission short section 4.

[0038] In one embodiment, Figure 2 , Figure 3 , Figure 4As shown, the stator bushing 22 and the screw rotor 23 are respectively made of bendable materials, and the inner wall of the stator bushing 22 is provided with a threaded flow channel 24, and the threaded flow channel 24 matches with the thread on the screw rotor 23. When the drilling fluid flows through the threaded flow channel 24, under the drilling fluid pressure difference and the conjugate action of the stator bushing 22 and the screw rotor 23, the screw rotor 23 can make planetary motion along the circumference of the stator bushing 22, and convert the planetary motion into axial motion through the transmission short section 4 and transmit it to the drill bit 5, so that the drill bit 5 rotates along its own axis.

[0039] The flexible screw drill for ultra-short radius drilling in this embodiment uses drilling fluid as the driving medium. When the drilling fluid flows through the threaded flow channel 24, under the drilling fluid pressure difference and the conjugate action of the stator bushing 22 and the screw rotor 23, the screw rotor 23 can make planetary motion along the circumference of the stator bushing 22, and convert the planetary motion into axial motion through the transmission short section 4 and transmit it to the drill bit 5, so that the drill bit 5 rotates along its own axis. This design can shorten the distance between the power source and the drill bit 5, thereby improving the torque transmission efficiency, ensuring the rotation speed of the drill bit 5, and improving the operation time efficiency. At the same time, since the screw rotor 23, the stator bushing 22 and the stator housing 21 can be bent, and the length of the entire screw drill is reduced, it can not only effectively reduce the radius of curvature and realize ultra-short radius drilling, but also extend the horizontal section extension distance, and realize the adjustment of the drilling trajectory.

[0040] In this embodiment, the bottom end of the screw rotor 23 is connected to the universal shaft in the transmission subsection 4, and the drill bit 5 is connected to the transmission shaft in the transmission subsection 4. The planetary motion of the screw rotor 23 is converted into the axial motion of the transmission shaft and transmitted to the drill bit 5 through the universal shaft, so that the torque of the screw rotor 23 is transmitted to the drill bit 5. Since the transmission subsection 4 is a prior art, it will not be described in detail here.

[0041] In one embodiment, Figure 3 , Figure 4 As shown, the screw rotor 23 can be made of a bendable material with a certain rigidity such as tin bronze, zinc white copper, beryllium bronze or silicon manganese steel, the stator bushing 22 is made of rubber material, and the stator is vulcanized and fixed to the inner wall of the flexible drill shell.

[0042] In one embodiment, Figure 2 , Figure 5 As shown, the stator housing 21 is composed of multiple universal joints 6 connected in series. The universal joint 6 located at the top is threadedly connected to the upper joint 1, and the universal joint 6 located at the bottom is threadedly connected to the lower joint 3. Since two adjacent universal joints 6 can rotate relative to each other, the entire stator housing 21 can bend with the stator sleeve 22.

[0043] In one embodiment, Figure 5 , Figure 6As shown, each universal joint 6 comprises a universal sleeve 61, a support sleeve 62, a support shaft 63 and a universal ball 64. The universal sleeve 61 and the support sleeve 62 are respectively sleeved on the stator sleeve 22, and the support sleeve 62 is located below the universal sleeve 61. The bottom end of the support shaft 63 is located in the support sleeve 62 and is threadedly connected to the support sleeve 62. The universal ball 64 is integrally connected to the top end of the support shaft 63 and forms a universal rotation fit with the universal sleeve 61. At the same time, a clearance hole 65 is provided through the support shaft 63 and the universal ball 64. The stator sleeve 22 passes through the clearance hole 65, and the stator sleeve 22 is fixed to the universal sleeve 61, the support sleeve 62, the support shaft 63 and the universal ball 64 by vulcanization.

[0044] In one embodiment, Figure 5 , Figure 6 As shown, each universal sleeve 61 is threadedly connected with a limited rotation pin 7, and each universal ball 64 is provided with a limited rotation groove 8. The limited rotation pin 7 is located in the corresponding limited rotation groove 8, and a limited rotation gap 9 is formed between the outer wall of the limited rotation pin 7 and the inner wall of the corresponding limited rotation groove 8 to limit the rotation angle of the universal ball 64 relative to the universal sleeve 61, thereby facilitating the control of the posture of the screw drill.

[0045] In one embodiment, Figure 5 , Figure 6 As shown, the lower end of each universal sleeve 61 is integrally formed with a limit ring 10, and the limit ring 10 abuts against the lower spherical surface of the corresponding universal ball 64. At the same time, the inner side wall of each limit ring 10 is respectively provided with a first guide arc surface 11, and the first guide arc surface 11 is closely matched with the lower spherical surface of the corresponding universal ball 64 to improve the guiding effect, so that the universal ball 64 can rotate smoothly.

[0046] In one embodiment, Figure 5 , Figure 6 As shown, the outer side wall of the upper joint 1 and each support sleeve 62 is respectively provided with an external thread 12, and the inner side wall of each universal sleeve 61 is respectively provided with an internal thread 13, and the external thread 12 matches the internal thread 13. When the universal sleeve 61 is threadedly connected with the upper joint 1 or the corresponding support sleeve 62, the bottom end of the upper joint 1 or the universal sleeve 61 abuts against the upper spherical surface of the corresponding universal ball 64. At the same time, the bottom end of the upper joint 1 and each universal sleeve 61 is respectively provided with a second guide arc surface 14, and the second guide arc surface 14 is closely matched with the upper spherical surface of the corresponding universal ball 64 to improve the guiding effect, so that the universal ball 64 can rotate smoothly.

[0047] In one embodiment, Figure 5 , Figure 6As shown, a sealing ring 15 is fixedly embedded on each second guide arc surface 14 , and the sealing ring 15 is in close contact with the upper spherical surface of the corresponding universal ball 64 to improve the sealing effect between the universal ball 64 and the upper joint 1 or the support sleeve 62 .

[0048] It can be seen from the above process that the use of the flexible screw drill can shorten the distance between the power source and the drill bit 5, thereby improving the torque transmission efficiency, ensuring the rotation speed of the drill bit 5, and improving the operation time efficiency. At the same time, since the screw rotor 23, the stator bushing 22 and the stator housing 21 can be bent, and the length of the entire screw drill is reduced, it can not only effectively reduce the radius of curvature and achieve ultra-short radius drilling, but also extend the horizontal section extension distance. In addition, during the horizontal drilling of the screw drill, when the downhole measurement signal detects a large change in the well inclination angle, the turntable drive can be stopped to adjust the tool face, and the drilling pressure and rotation speed can be adjusted, and sliding drilling can be used to control the wellbore trajectory within the reservoir to control the drilling trajectory.

[0049] It should be noted that, unless otherwise specified, the technical terms or scientific terms used in the present invention should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0050] In addition, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. In the description of the present invention, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A flexible screw drill for ultra-short radius drilling, characterized in that: The invention comprises an upper joint (1), a power unit (2), a lower joint (3), a transmission short section (4) and a drill bit (5) which are connected in sequence from top to bottom, wherein the power unit (2) comprises: A stator housing (21), the top end of which is connected to the upper joint (1) and the bottom end of which is connected to the lower joint (3), and the stator housing (21) is bendable; A stator bushing (22) fixed on the inner wall of the stator housing (21); A screw rotor (23) is disposed in the stator bushing (22) and is conjugately matched with the stator bushing (22), and the bottom end of the screw rotor (23) is connected to the transmission short section (4); The stator bushing (22) and the screw rotor (23) are respectively made of bendable materials. The inner wall of the stator bushing (22) is provided with a threaded flow channel (24), and the threaded flow channel (24) matches with the thread on the screw rotor (23). When drilling fluid flows through the threaded flow channel (24), under the drilling fluid pressure difference and the conjugate action of the stator bushing (22) and the screw rotor (23), the screw rotor (23) performs planetary motion along the circumference of the stator bushing (22), and converts the planetary motion into axial motion through the transmission short section (4) and transmits it to the drill bit (5), so that the drill bit (5) rotates along its own axis.

2. The flexible screw drill according to claim 1, characterized in that: The stator liner (22) is made of rubber material, and the stator liner (22) is fixed on the inner side wall of the stator housing (21) by vulcanization.

3. The flexible screw drill according to claim 1, characterized in that: The stator housing (21) is composed of a plurality of universal joints (6) connected in series, wherein the universal joint (6) located at the top is connected to the upper joint (1), and the universal joint (6) located at the bottom is connected to the lower joint (3).

4. The flexible screw drill according to claim 3, characterized in that: Each of the universal joints (6) comprises: A universal sleeve (61) fixedly sleeved on the stator sleeve (22); A support sleeve (62), which is fixedly mounted on the stator sleeve (22) and is located below the universal sleeve (61); A support shaft (63), the top end of which is located in the universal sleeve (61) and the bottom end of which is threadedly connected to the support sleeve (62); A universal ball (64) is integrally formed and connected to the top end of the support shaft (63) and forms a universal rotation fit with the universal sleeve (61); The clearance hole (65) passes through the support shaft (63) and the universal ball (64), and the stator bushing (22) passes through the clearance hole (65) and is fixedly connected to the support shaft (63) and the universal ball (64).

5. The flexible screw drill according to claim 4, characterized in that: A limited rotation pin (7) is respectively threadedly connected to each of the universal sleeves (61), and a limited rotation groove (8) is respectively arranged on each of the universal balls (64). The limited rotation pin (7) is located in the corresponding limited rotation groove (8), and a limited rotation gap (9) is formed between the outer side wall of the limited rotation pin (7) and the inner side wall of the corresponding limited rotation groove (8) to limit the rotation angle of the universal ball (64) relative to the universal sleeve (61).

6. The flexible screw drill according to claim 4, characterized in that: A limiting ring (10) is integrally formed at the lower end of each universal sleeve (61), and the limiting ring (10) abuts against the lower spherical surface of the corresponding universal ball (64).

7. The flexible screw drill according to claim 6, characterized in that: The inner side wall of each of the limiting rings (10) is respectively provided with a first guiding arc surface (11), and the first guiding arc surface (11) is tightly matched with the lower end spherical surface of the corresponding universal ball (64).

8. The flexible screw drill according to claim 4, characterized in that: The outer side walls of the upper joint (1) and each of the support sleeves (62) are respectively provided with external threads (12), and the inner side walls of each of the universal sleeves (61) are respectively provided with internal threads (13), and the external threads (12) match the internal threads (13). When the universal sleeve (61) is threadedly connected with the upper joint (1) or the corresponding support sleeve (62), the bottom end of the upper joint (1) or the universal sleeve (61) abuts against the upper spherical surface of the corresponding universal ball (64).

9. The flexible screw drill according to claim 8, characterized in that: The upper joint (1) and the bottom end of each universal sleeve (61) are respectively provided with a second guide arc surface (14), and the second guide arc surface (14) is tightly matched with the upper end spherical surface of the corresponding universal ball (64).

10. The flexible screw drill according to claim 9, characterized in that: A sealing ring (15) is fixedly embedded on each of the second guide arc surfaces (14), and the sealing ring (15) is in tight contact with the upper spherical surface of the corresponding universal ball (64).

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