Flexible drilling tool structure

Abstract

The invention discloses a flexible drilling tool structure which comprises a top drive and a hollow shaft connected with the top drive and further comprises a flexible drilling rod body, a guide screen pipe, an anti-torque assembly and a rolling resistance reduction assembly. The flexible drill rod body is composed of a plurality of sub-flexible drill rods, and one end of the flexible drill rod body is connected with the other end of the hollow shaft. The guiding screen pipe is arranged on the inner side of the flexible drill rod body in a penetrating mode, and the outer wall of the guiding screen pipe is rotationally connected with the inner wall of the flexible drill rod body through a tapered roller bearing. The anti-torsion assembly comprises a pressing pipe and a plurality of anti-torsion balls. The rolling resistance reduction assembly comprises a first annular mounting seat and a plurality of resistance reduction balls; the guide screen pipe is innovatively arranged in the flexible drill rod, the guide screen pipe is connected with the top drive through the anti-torsion assembly, the guide screen pipe can independently bear axial force so as to control the drilling track in the horizontal direction, and the guide screen pipe and the flexible drill rod are connected through the tapered roller bearing; through cooperation with the rolling resistance reduction assembly arranged on the outer wall of the flexible drill rod, friction is reduced, and therefore the horizontal drilling extension length is increased.

Description

Technical Field

[0001] The invention relates to the technical field of drilling tools, in particular to a flexible drilling tool structure. Background Art

[0002] Ultra-short-radius horizontal wells are a special well type, notably characterized by a build-up section with a radius of curvature less than 4 meters. Compared to conventional or long-radius horizontal wells, ultra-short-radius horizontal wells enable a rapid transition from vertical to horizontal sections within a very short wellbore distance. This design significantly enhances wellbore flexibility, enabling it to adapt to complex geological conditions and specialized oil and gas reservoir development requirements.

[0003] Ultra-short radius horizontal wells are primarily used to tap the potential of residual oil in remote locations of high-aquifer formations, tap the potential of casing-damaged, abandoned wells, and develop unconventional reservoirs. In mature oilfield development, the remaining oil in remote locations of high-aquifer formations is difficult to effectively tap using traditional methods. Ultra-short radius horizontal well technology uses flexible drilling tools to tap the potential of residual oil in remote locations of the original wellbore by sidetracking through casing windows. In mature oilfields, severe casing corrosion, faulting, and deformation can lead to the closure of some wells beyond repair. Ultra-short radius horizontal well technology can be applied in casing-damaged and abandoned wells. By opening windows at high positions and advancing into layers with large curvatures to quickly tap the potential of remaining oil, the abandoned wells can be reused. For thin oil layers, its high-precision penetration capability and long horizontal sections can significantly increase the oil leakage area, making up for the insufficient thickness of a single layer. In reservoirs with developed vertical fractures, the horizontal section can cross multiple fractures to form efficient seepage channels, while avoiding the damage to fractures caused by long radius drilling. For heavy oil production, ultra-short radius horizontal wells can be combined with thermal recovery technology to reduce heat loss through uniform steam injection in the horizontal section, and use multi-branch wellbores to improve heating efficiency. For low permeability reservoirs, the horizontal section extends the seepage path, and combined with volume fracturing, it can significantly improve production capacity.

[0004] Conventional rigid drilling tools are no longer able to meet the design requirements for addressing the high bending and load transfer challenges faced by drilling tools in the curvature sections of ultra-short-radius horizontal wells. In this situation, flexible drilling tools are crucial for resolving this technical challenge. With their excellent bending adaptability, flexible drilling tools can effectively handle wellbore trajectories with drastically varying curvatures. This design not only meets the stringent requirements of ultra-short-radius horizontal wells but also provides reliable support for oil and gas production in complex geological conditions.

[0005] Currently, flexible drilling tools are generally divided into two types. The first type uses a single layer of multiple sections of flexible drill pipes that are hinged to each other to form a flexible drilling tool as a whole. During the horizontal drilling process, since each section of the drill pipe is hingedly connected, although it has the advantage of a long horizontal extension distance, it is difficult to control its horizontal drilling trajectory, causing the drilled wellbore trajectory to deviate from the designed wellbore trajectory. The second type uses a double-layer structure, with the inner layer being a flexible drill pipe and the outer layer being a guide screen. During the horizontal drilling process of this flexible drilling tool, the outer layer of the guide screen mainly controls the wellbore trajectory of the flexible drilling tool. The guide screen itself cannot withstand torque, so the axial force and torque are all borne by the flexible drill pipe. However, there is a huge friction between the outer layer of the guide screen and the well wall, which causes this double-layer flexible drilling tool structure to have the defect of limited horizontal drilling extension distance. Summary of the Invention

[0006] The purpose of the present invention is to provide a flexible drilling tool structure to solve the problem that the existing flexible drilling tools are difficult to control the horizontal drilling trajectory and the horizontal drilling extension length is not limited.

[0007] The technical solution of the present invention is: A flexible drilling tool structure includes a top drive and a hollow shaft, wherein the top drive is connected to the hollow shaft, and further includes a flexible drill rod body, a guide screen, an anti-torsion component and a rolling drag reduction component; the flexible drill rod body is composed of multiple sections of flexible drill rods, and two adjacent sections of flexible drill rods are hinged to each other end to end, and one end of the flexible drill rod body is connected to the other end of the hollow shaft; the guide screen is passed through the inner side of the flexible drill rod body, and the outer wall of the guide screen is rotatably connected to the inner wall of the flexible drill rod body through a tapered roller bearing; the anti-torsion component includes a pressure tube and multiple anti-torsion balls, and the pressure tube is passed through the hollow shaft. Inside the core shaft, a plurality of hemispherical notches are opened around the end face of the pressure tube facing the top drive, one side of the plurality of anti-torsion balls is respectively located in the plurality of hemispherical notches, and the other side of the plurality of anti-torsion balls is in contact with the end face of the top drive, and the outer wall of the other end of the pressure tube is connected to the pipe mouth of the guide screen pipe; the rolling drag reduction assembly includes a first annular mounting seat and a plurality of drag reduction balls, the first annular mounting seat is fixedly sleeved on the outer wall of the sub-flexible drill pipe, and the plurality of drag reduction balls are embedded in the circumferential outer wall of the first annular mounting seat, and the height of the drag reduction balls is higher than the height of the first annular mounting seat.

[0008] Preferably, as a further improvement of the present invention, a plurality of mounting slots are evenly distributed on the circumferential outer wall of the first annular mounting seat, the cross-section of the mounting slots is U-shaped, and the plurality of drag-reducing balls are installed in the plurality of mounting slots one by one, and an anti-slip component is provided on the inner wall of the hole opening of each mounting slot, and the anti-slip component is used to prevent the drag-reducing balls from falling off.

[0009] Preferably, as a further improvement of the present invention, the anti-slip component is a fixed ring, the fixed ring is fixed on the inner wall of the hole opening of the mounting slot, and the arc surface on one side of the drag-reducing ball is slidably connected to the fixed ring.

[0010] Preferably, as a further improvement of the present invention, the plurality of mounting slots are distributed along a spiral trajectory on the circumferential side wall of the first annular mounting seat.

[0011] Preferably, as a further improvement of the present invention, the surfaces of the anti-torsion balls and the drag-reducing balls are both provided with a wear-resistant coating.

[0012] Preferably, as a further improvement of the present invention, the wear-resistant coating is made of carbon fiber or polytetrafluoroethylene.

[0013] Preferably, as a further improvement of the present invention, an annular mounting cavity is provided on the end of the first annular mounting seat facing away from the top drive, a second annular mounting seat is inserted into the annular mounting cavity, the second annular mounting seat is connected between two adjacent sections of sub-flexible drill pipe, the second annular mounting seat is located in the annular mounting cavity and a second mounting hole is provided through the circumferential side wall thereof, an arc-shaped groove is provided on the outer wall of the sub-flexible drill pipe facing the second mounting hole, a ball stud key is passed through the second mounting hole, and one end of the ball stud key is in sliding contact with the arc-shaped groove.

[0014] Preferably, as a further improvement of the present invention, a sealing assembly is provided between the second annular mounting seat and two adjacent sections of flexible drill rod, and the sealing assembly includes a first sealing ring and a second sealing ring, the first sealing ring is fixed between the second annular mounting seat and one section of the flexible drill rod, and the second sealing ring is fixed between the second annular mounting seat and the other section of the flexible drill rod.

[0015] Preferably, as a further improvement of the present invention, the number of the sub-flexible drill rods is N, N is a positive integer, and N≥2, and the number of the first annular mounting seat and the second annular mounting seat are both N-1.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The original power transmission structure was optimized and a new power transmission system was set up. The guide screen was innovatively built into the flexible drill pipe, and the guide screen and the flexible drill pipe were connected by a tapered roller bearing. In addition, by cooperating with the rolling drag reduction component set on the outer wall of the flexible drill pipe, multiple drag reduction balls were used to significantly reduce the friction resistance during horizontal drilling, reduce the additional energy loss caused by friction, and thus increase the horizontal drilling extension length. At the same time, due to the presence of the anti-torsion component, independent loading of torque and axial force between the flexible drill pipe body and the guide screen was achieved, so that the guide screen itself would not bear torque, but could bear axial force alone, so that the horizontal drilling trajectory could be controlled by the guide screen during drilling to ensure that the drilling trajectory of the flexible drilling tool is not affected.

[0017] 2. It realizes the layered transfer of load and improves drilling efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the three-dimensional structure of a flexible drilling tool structure according to an embodiment of the present invention.

[0019] Figure 2 For the present invention Figure 1 Schematic diagram of the cross-sectional structure at AA in FIG.

[0020] Figure 3 For the present invention Figure 2 A partial enlarged schematic diagram of point B in FIG.

[0021] Figure 4 For the present invention Figure 2 A partial enlarged schematic diagram of point C in FIG.

[0022] Figure 5 For the present invention Figure 2 A local enlarged schematic diagram of point D in the figure. DETAILED DESCRIPTION

[0023] The following combination Figures 1 to 5 , a detailed description of the specific embodiments of the present invention is provided. In the description of the invention, it should be understood that the terms "center," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inside," "outside," and the like, indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific direction, be constructed, or operate in a specific direction. Therefore, they should not be construed as limiting the present invention.

[0024] The terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the quantity of the technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include one or more of such features; and in the description of the invention, unless otherwise specified, "plurality" means two or more.

[0025] Example like Figures 1 to 5 As shown, an embodiment of the present invention provides a flexible drilling tool structure, including a top drive 1 and a hollow shaft 2, the top drive 1 is connected to the hollow shaft 2, and also includes a flexible drill pipe body 3, a guide screen 4, an anti-torsion component and a rolling drag reduction component; the flexible drill pipe body 3 is composed of multiple sections of flexible drill pipes, and the multiple sections of flexible drill pipes are hinged to each other at the head and tail, and one end of the flexible drill pipe body 3 is connected to the other end of the hollow shaft 2; the guide screen 4 is passed through the inner side of the flexible drill pipe body 3, and the outer wall of the guide screen 4 is rotatably connected to the inner wall of the flexible drill pipe body 3 through a tapered roller bearing 5; the anti-torsion component includes a pressure pipe 6 and multiple anti-torsion balls 7, and the pressure The tube 6 is passed through the inside of the hollow shaft 2, and a plurality of hemispherical notches are arranged around the end face of the pressure tube 6 facing the top drive 1. One side of the plurality of anti-torsion balls 7 is respectively located in the plurality of hemispherical notches, and the other side of the plurality of anti-torsion balls 7 is in contact with the end face of the top drive 1. The outer wall of the other end of the pressure tube 6 is connected to the pipe mouth of the guide screen pipe 4; the rolling drag reduction assembly includes a first annular mounting seat 8 and a plurality of drag reduction balls 9, the first annular mounting seat 8 is fixedly sleeved on the outer wall of the sub-flexible drill pipe, and the plurality of drag reduction balls 9 are embedded in the circumferential outer wall of the first annular mounting seat 8, and the height of the drag reduction balls 9 is higher than the height of the first annular mounting seat 8.

[0026] In this embodiment, the guide screen tube 4 is placed inside the flexible drill pipe body 3, and the two are connected by a tapered roller bearing 3. The tapered roller bearing 3 can withstand large radial loads and axial loads at the same time. When the guide screen tube 4 is subjected to the axial load, the relative position between the guide screen tube 4 and the flexible drill pipe body 3 is guaranteed to remain unchanged, so that the connection stability between the flexible drill pipe body 3 and the guide screen tube 4 can be maintained. By cooperating with the rolling drag reduction component, the rolling drag reduction component provided on the outer wall of the flexible drill pipe body 3 can reduce the friction resistance during horizontal drilling through multiple drag reduction balls 9 during drilling, reducing the additional energy loss caused by friction, thereby increasing the horizontal drilling extension length; at the same time, the top drive 1 is driven by an electric motor as a power source, can output torque and axial force, and the hollow One end of the shaft 2 is rigidly connected to the top drive 1, and the other end of the hollow shaft 2 is threadedly connected to the flexible drill pipe body 3. The power transmitted by the power source can be transmitted to the flexible drill pipe body 3 through the hollow shaft 2. One end of the pressure pipe 6 is threadedly connected to the guide screen pipe 4. A plurality of anti-torsion balls 7 are distributed between the top drive 1 and the end face of the other end of the pressure pipe 6. Due to the presence of the plurality of anti-torsion balls 7, the power transmitted from the top drive 1 to the guide screen pipe 4 is only axial force, which realizes the independent loading of torque and axial force between the flexible drill pipe body and the guide screen pipe, so that the guide screen pipe itself will not bear torque, but can bear axial force alone, so that the guide screen pipe can be used to control the horizontal drilling trajectory during drilling to ensure that the drilling trajectory of the flexible drilling tool is not affected. The overall coordination of the combined flexible drilling tool realizes the layered transmission of load and improves drilling efficiency.

[0027] Among them, top drive 1 is realized by using model TDS-250 top drive, with 450kW power and continuous torque of 40.1kn / m.

[0028] Furthermore, a plurality of mounting slots are evenly distributed on the circumferential outer wall of the first annular mounting seat 8, and the cross-section of the mounting slot is U-shaped. The plurality of drag-reducing balls 9 are installed in the plurality of mounting slots one by one, and an anti-slip component 10 is provided on the inner wall of the opening of each mounting slot. Specifically, the anti-slip component 10 is a fixing ring, which is fixed on the inner wall of the opening of the mounting slot, and one side arc surface of the drag-reducing ball 9 is slidably connected in the fixing ring.

[0029] In the specific implementation, the diameter of the installation slot is 10mm and the depth is 7.5mm. A drag-reducing ball 9 with a diameter of 10mm is installed in the slot. At the same time, a fixing ring is used to limit the position of the ball, successfully transforming the surface contact between the traditional flexible drilling tool and the well wall into point contact between the drag-reducing ball 9 and the well wall. This improvement greatly reduces the contact area while ensuring the strength of the flexible drilling tool, thereby significantly reducing friction resistance and improving the operating efficiency and durability of the flexible drilling tool.

[0030] As a preferred embodiment, in this embodiment, multiple mounting slots are distributed along a spiral trajectory on the circumferential side wall of the first annular mounting seat 8. Through the above-mentioned setting, the arrangement of multiple drag-reducing balls 9 can coincide with the trajectory of spiral drilling, which can further reduce friction during the drilling process.

[0031] Furthermore, in order to avoid wear, a wear-resistant coating is provided on the surfaces of the anti-torsion balls 7 and the drag-reducing balls 9.

[0032] Among them, the wear-resistant coating is made of carbon fiber or polytetrafluoroethylene. It has excellent wear resistance and self-lubricating properties, making it more suitable for use in scenarios where friction needs to be reduced.

[0033] In another embodiment of the present invention, an annular mounting cavity is provided at the end of the first annular mounting seat 8 facing away from the top drive 1, and a second annular mounting seat 12 is inserted into the annular mounting cavity. The second annular mounting seat 12 is connected between two adjacent sections of sub-flexible drill pipes. The second annular mounting seat 12 is located in the annular mounting cavity and a second mounting hole is provided through the circumferential side wall thereof. An arc-shaped groove 31 is provided on the outer wall of the sub-flexible drill pipe facing the second mounting hole. A ball stud key 11 is passed through the second mounting hole, and one end of the ball stud key 11 is in sliding contact with the arc-shaped groove 31.

[0034] Through the above arrangement, the ball stud key 11 can move in the recess on the flexible drill rod during rotation, thereby achieving relative rotation between the two sections of flexible sub-drill rods to adapt to the bending and deflecting process.

[0035] Furthermore, a sealing assembly is provided between the second annular mounting seat 12 and two adjacent sections of flexible drill pipe, and the sealing assembly includes a first sealing ring 13 and a second sealing ring 14. The first sealing ring 13 is fixed between the second annular mounting seat 12 and one section of the flexible drill pipe, and the second sealing ring 14 is fixed between the second annular mounting seat 12 and the other section of the flexible drill pipe. The first sealing ring 13 is a circular sealing ring, and the second sealing ring 14 is a square sealing ring. The first sealing ring 13 and the second sealing ring 14 are provided to prevent leakage of drilling fluid.

[0036] Furthermore, the number of sub-flexible drill rods is N, N is a positive integer, and N≥2, and the number of first annular mounting seats 8 and second annular mounting seats 12 are both N-1. Such a setting can adjust the length of the flexible drilling tool according to design requirements.

[0037] The above disclosures are only several preferred specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the scope of protection of the present invention.

Claims

1. A flexible drilling tool structure, comprising a top drive (1) and a hollow shaft (2), wherein the top drive (1) is connected to the hollow shaft (2), and is characterized in that: Also includes: The flexible drill rod body (3) is composed of multiple sections of flexible drill rods, and two adjacent sections of flexible drill rods are hinged to each other end to end, and one end of the flexible drill rod body (3) is connected to the other end of the hollow shaft (2); A guide screen tube (4) is provided on the inner side of the flexible drill rod body (3), and the outer wall of the guide screen tube (4) and the inner wall of the flexible drill rod body (3) are rotatably connected via a tapered roller bearing (5); An anti-torsion component comprises a pressure tube (6) and a plurality of anti-torsion balls (7), wherein the pressure tube (6) is passed through the interior of the hollow shaft (2), and a plurality of hemispherical notches are formed around the end surface of the pressure tube (6) facing the top drive (1), one side of the plurality of anti-torsion balls (7) is respectively located in the plurality of hemispherical notches, and the other side of the plurality of anti-torsion balls (7) abuts against the end surface of the top drive (1), and the outer wall of the other end of the pressure tube (6) is connected to the pipe opening of the guide screen tube (4); The rolling drag reduction assembly comprises a first annular mounting seat (8) and a plurality of drag reduction balls (9), wherein the first annular mounting seat (8) is fixedly sleeved on the outer wall of the sub-flexible drill pipe, and the plurality of drag reduction balls (9) are embedded on the circumferential outer wall of the first annular mounting seat (8), and the height of the drag reduction balls (9) is higher than that of the first annular mounting seat (8).

2. The flexible drilling tool structure according to claim 1, characterized in that: A plurality of mounting slots are evenly distributed on the circumferential outer wall of the first annular mounting seat (8), and the cross-section of the mounting slots is U-shaped. The plurality of drag-reducing balls (9) are mounted in the plurality of mounting slots in a one-to-one correspondence, and an anti-slipping member (10) is provided on the inner wall of the opening of each mounting slot, and the anti-slipping member (10) is used to prevent the drag-reducing balls (9) from falling off.

3. The flexible drilling tool structure according to claim 2, characterized in that: The anti-slip component (10) is a fixed ring, which is fixed to the inner wall of the opening of the installation slot hole, and the arc surface on one side of the drag-reducing ball (9) is slidably connected to the fixed ring.

4. The flexible drilling tool structure according to claim 2, characterized in that: The plurality of mounting slots are distributed along a spiral trajectory on the circumferential side wall of the first annular mounting seat (8).

5. The flexible drilling tool structure according to claim 1, characterized in that: The surfaces of the anti-torsion balls (7) and the drag-reducing balls (9) are both provided with wear-resistant coatings.

6. The flexible drilling tool structure according to claim 5, characterized in that: The material of the wear-resistant coating is carbon fiber or polytetrafluoroethylene.

7. The flexible drilling tool structure according to claim 1, characterized in that: An annular mounting cavity is provided at one end of the first annular mounting seat (8) facing away from the top drive (1), a second annular mounting seat (12) is inserted into the annular mounting cavity, the second annular mounting seat (12) is connected between two adjacent sections of the sub-flexible drill pipe, a second mounting hole is provided through the circumferential side wall of the second annular mounting seat (12) located in the annular mounting cavity, an arc-shaped groove (31) is provided on the outer wall of the sub-flexible drill pipe facing the second mounting hole, a ball stud key (11) is passed through the second mounting hole, and one end of the ball stud key (11) is in sliding contact with the arc-shaped groove (31).

8. The flexible drilling tool structure according to claim 7, characterized in that: A sealing assembly is provided between the second annular mounting seat (12) and two adjacent sections of flexible drill rod, the sealing assembly comprising a first sealing ring (13) and a second sealing ring (14), the first sealing ring (13) being fixed between the second annular mounting seat (12) and one section of the flexible drill rod, and the second sealing ring (14) being fixed between the second annular mounting seat (12) and the other section of the flexible drill rod.

9. The flexible drilling tool structure according to claim 8, characterized in that: The number of the sub-flexible drill rods is N, N is a positive integer, and N≥2, and the number of the first annular mounting seats (8) and the second annular mounting seats (12) are both N-1.

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