A flexible drilling tool with automatic drill feeding

Abstract

The present invention belongs to the field of drilling and hole-boring technology, and is particularly directed to an automatic drill-feeding flexible drilling tool, comprising a drill bit, a plurality of drill-feeding short sections and a series of joint short sections, wherein an annular cavity and a spacer ring are provided in the drill-feeding short section, thereby isolating a low-pressure cavity in the annular cavity, and a first through hole connecting the low-pressure cavity and the annulus is provided on the drill-feeding short section. During the drilling process, the outside of the drill-feeding short section is filled with low-pressure liquid, while the inside of the push rod portion in the drill-feeding short section is filled with high-pressure liquid. Therefore, the spacer ring is forced to receive a thrust toward the low-pressure cavity, thereby pushing the drilling tool forward and flexibly applying drilling pressure. The automatic drill-feeding flexible drilling tool is connected to a flexible drill rod, and adjacent short sections are connected by joint short sections, which greatly shortens the rigid length of the tool assembly and helps solve the practical problems of severe support pressure and difficulty in drilling during guided drilling with a small curvature radius.

Description

Technical Field

[0001] The invention belongs to the technical field of exploration drilling tools, and in particular relates to an automatic drill feeding flexible drilling tool. Background Art

[0002] In the field of oil and gas exploration, directional drilling technology can artificially control the wellbore trajectory to drill towards the pre-designed target layer. This technology enables the drill bit to bypass obstacles to reach the oil reservoir, and can explore scattered oil reservoirs and heavy oil reservoirs. It has more advantages than traditional vertical well exploration. For example, in oil and natural gas extraction, drilling branch wells through directional drilling technology can significantly improve the development efficiency of oil and gas reservoirs. The branch wells here are branch wellbores connected to the main well, which is equivalent to increasing the channel for oil or gas production, which will naturally improve development efficiency and have obvious economic benefits.

[0003] In the prior art, Chinese patent document with publication number CN2135055Y describes a flexible articulated steering power drilling tool, and Chinese patent document with publication number CN2548742Y describes a ball joint universal joint in a multi-axis drill.

[0004] However, current drilling tools still have the following shortcomings: First, the rigid section of existing conventional directional drilling tools is relatively long, making it difficult to drill well sections with a small curvature radius and a large turning range during drilling; Second, there will be a pressure-supporting phenomenon during the drilling process of the drilling tool, that is, due to the excessive friction between the downhole drilling tool and the well wall, all the drilling pressure is applied to the drilling tool and cannot be applied to the drill bit, resulting in jamming or obstruction during the drilling process, resulting in slow drilling. Summary of the Invention

[0005] The present invention aims to provide an automatic drill bit feeding flexible drilling tool, which solves the technical problem in the prior art that flexible drilling tools are difficult to get out of trouble after generating support pressure during drilling.

[0006] In order to solve the above technical problems, the present invention is achieved by the following technical means:

[0007] An automatic drill feeding flexible drilling tool comprises a drill bit, a plurality of drill feeding subs, and a series of articulated subs. The series of articulated subs comprises a plurality of articulated subs, each of which comprises an articulated structure for deflectable mutual connection. The drill feeding subs comprise a combined sleeve cylinder that can generate axial thrust under hydraulic action to propel the drill bit forward. When the automatic drill feeding flexible drilling tool comprises a plurality of drill feeding subs, the drill feeding subs are connected by articulated structures. The drill feeding subs and the articulated subs are both connected by articulated structures. The drill bit is disposed at the drill feeding subs or at the lower end of the articulated subs. At least one drill feeding sub is disposed at the lower half of the automatic drill feeding flexible drilling tool. The distance between the deflection points of the articulated structures on both sides of the drill feeding subs is between 1 and 5 times the diameter of the drill bit, and the distance between the deflection point of the articulated structure in the articulated subs and the adjacent deflection point of the articulated structure is between 0.5 and 4 times the diameter of the drill bit.

[0008] Preferably, the drill delivery sub is provided with a thrust piston, which includes a push rod portion and a spacer ring; hydraulic chambers are respectively provided above and below the spacer ring; at least one of the chambers is connected to the flow channel inside the drilling tool, and the drill delivery sub is provided with a first through hole connecting the low-pressure chamber and the annulus, and the other cavity is connected to the annulus through the first through hole.

[0009] The drill feed sub is provided with a hollow thrust piston, which includes a push rod portion and a connecting joint portion; at least one annular cavity is provided between the push rod portion and the inner wall of the drill feed sub, a spacer ring is provided in the annular cavity to isolate a low-pressure cavity, and a first through hole is provided on the drill feed sub to connect the low-pressure cavity and the annulus;

[0010] The drill feed sub is provided with a hollow drill feed joint at the rear end. The drill feed joint is provided with a connecting structure for mounting the connecting joint portion. The connecting joint portion can be assembled into the connecting structure via threads or other means. When the push rod portion moves axially within the drill feed sub, the connecting joint portion can apply thrust to the drill feed joint. It should be noted that the drill feed sub itself can be used inverted, with the drill feed joint on the side of the drill feed sub close to the drill bit or on the side of the drill feed sub away from the drill bit.

[0011] Preferably, the automatic drill feeding flexible drilling tool includes a plurality of drill feeding subs.

[0012] Preferably, the drill feed joint can be integrally formed with the drill feed short section as a shell, and the shell is divided into two relatively movable but non-detachable parts by a closed continuous curved gap, and the axial displacement of the thrust piston is limited by the gap. Or it can be divided in the form of a toothed slot or the like, and the relative movement mainly refers to the ability to satisfy the axial relative displacement between the two. At the same time, when the lower shell section separated by a closed continuous curved slot or composed of a toothed slot structure is suspended on the upper shell section, it can withstand the weight of the drilling tool combination below and the axial tension during the process of lifting the drilling tool. When the upper and lower shell sections are in close contact, the drilling pressure can be transmitted. The setting of the axial relative displacement satisfies the possibility that the thrust piston pushes the drill feed joint forward during the drilling support pressure.

[0013] Alternatively, the drill feed sub and the drill feed nipple may be designed and assembled separately. The connecting joint may be directly connected and fixed to the drill feed sub via threads, and the drill feed nipple sub and the spacer ring or limit ring jointly limit the axial displacement of the thrust piston. When the drill feed nipple sub is in close contact with the drill feed sub shoulder, weight-on-bit is transmitted. During support pressure, the axial thrust of the thrust piston pushes the drill feed sub forward. During the raising or lowering process, the weight of the lower drilling tool is suspended from the drill feed nipple by the spacer ring.

[0014] Preferably, the inner wall of the drill feed sub, the outer wall of the push rod part and the spacer ring further isolate a high-pressure chamber in the annular chamber, and the push rod part is provided with a second through hole connecting the high-pressure chamber and the push rod part.

[0015] Preferably, the drill feed sub comprises at least one connecting sleeve, the front end and / or rear end of the connecting sleeve being connected to a hollow connector, and the annular cavity being located between the inner wall of the connecting sleeve, the outer wall of the thrust rod, and the corresponding end face of the connector.

[0016] Preferably, it may further include a guide power sub and / or a drill bit installed at the front end of the joint sub series. The drill feed sub is connected in series at any position in the joint sub series and can cooperate with the guide power sub to complete the guided drilling.

[0017] Each joint sub includes a first shell and a second shell connected front and back, and the first shell can be turned at a certain angle relative to the second shell; the steering power sub can be any tool or combination of tools that can achieve the steering function and provide bottom hole power for drilling;

[0018] Each of the joint short section, the drill feed short section, the guide power short section and the drill bit is provided with a communicating flow channel. It should be noted that the first shell and the second shell can be an integrally manufactured complete shell with an angle.

[0019] Preferably, the connecting shaft inside the drill delivery short section is a hollow cylindrical structure, and its second end shaft portion and the third end shaft portion are provided with threads or toothed connecting grooves to be connected to the adjacent power shaft or output shaft. When relative displacement occurs between the drill delivery short section joint and the connecting joint portion, in order not to affect the torque transmission at both ends of the connecting shaft, the straight section of the connecting shaft body must meet the thrust piston stroke, and the axial displacement between the second end shaft portion and the third end shaft portion should also meet the axial displacement during the axial torque transmission process to avoid jamming and causing the automatic drill delivery flexible drilling tool to fail.

[0020] Preferably, the front end of the first shell of the joint short section is correspondingly inserted into the rear end of the second shell, and a first gap for turning is provided between the front end of the first shell and the corresponding rear end of the second shell, and a sealing ring is provided in the first gap; a universal ball shaft is provided in the first shell and the second shell, and one end of the universal ball shaft is correspondingly located in the first shell, and the other end is correspondingly located in the second shell.

[0021] Preferably, it also includes a rigid drill string and a flexible section installed at the front end of the rigid drill string, the rigid drill string is hollow, the flexible section is installed at the front end of the rigid drill string, and the rigid drill string is used to apply bit pressure to the flexible section.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The drill delivery sub of the automatic drill delivery flexible drilling tool is provided with an annular cavity in the drill delivery sub, and a spacer ring is provided in the annular cavity, thereby isolating a low-pressure cavity in the annular cavity. A first through hole connecting the low-pressure cavity and the annulus is provided on the drill delivery sub. During the drilling process, the outside of the drill delivery sub is low-pressure liquid, while the inside of the push rod part in the drill delivery sub is high-pressure liquid. Therefore, the spacer ring is forced to be pushed toward the side of the low-pressure cavity, which plays a role in pushing the drilling tool forward, helping the drilling tool to solve the pressure support problem.

[0024] 2. Because the automatic drill feed flexible drilling tool features multiple articulated subs and drill feed subs, each relatively short, it increases the tool's overall maneuverability and significantly shortens the tool's rigid section, enabling it to meet the construction requirements of wellbores with small curvature radii. Furthermore, multiple drill feed subs connected in series provide sufficient hydraulic propulsion travel to meet the requirements of sliding steerable drilling. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are used to provide a further understanding 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 present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0026] Figure 1This is a cross-sectional view of an embodiment of the automatic drill feeding flexible drilling tool of the present invention.

[0027] Figure 2 This is a cross-sectional view of another embodiment of the automatic drill feeding flexible drilling tool of the present invention.

[0028] Figure 3 This is a cross-sectional view of another embodiment of the automatic drill feeding flexible drilling tool of the present invention.

[0029] Figure 4 This is a drilling schematic diagram of an embodiment of an automatic drill feed flexible drilling tool of the present invention.

[0030] Figure 5 It is a partial cross-sectional view of an embodiment of the automatic drill feeding flexible drilling tool of the present invention.

[0031] Figure 6 This is a schematic diagram of the connection between the drill feeding sub and the joint sub in one embodiment of the automatic drill feeding flexible drilling tool of the present invention.

[0032] Figure 7 for Figure 6 Magnified view of part A.

[0033] Figure 8 This is a schematic diagram of the connection between the power sub and the joint sub in one embodiment of the automatic drill feeding flexible drilling tool of the present invention.

[0034] Figure 9 for Figure 5 Enlarged view of part B.

[0035] In the figure, each number indicates:

[0036] Drill feed sub 1, connecting sleeve 11, first connector 12-1, second connector 12-2, third connector 12-3, fourth connector 12-4, fifth connector 12-5, sixth connector 12-6, seventh connector 12-7, spherical joint 12-7-1, first ball head seat 12-7-2, second ball head seat 12-7-3;

[0037] Thrust piston 2, push rod portion 21, connecting joint portion 22, third ball seat 22-1, fourth ball seat 22-2, first sealing ring 23;

[0038] Annular cavity 3, spacer ring 31, second sealing ring 32, low-pressure cavity 33, first through hole 34, high-pressure cavity 35, second through hole 36;

[0039] Drill feed joint 4, connecting structure 41;

[0040] Rigid drill string 10, second signal sub 101;

[0041] Guide power sub 20, third housing 201, power shaft 202, connecting groove 2021, universal ball key 2022, third flow hole 2023, third gap 203, rotor 204, stator 206, bearing 207;

[0042] Joint sub 30, first housing 301, second housing 302, universal ball joint 303, ball head 3031, first gap 304, third sealing ring 3041, fourth sealing ring 3042, first inner step 3043, second inner step 3044, ball seat 305, sealing sleeve 306, second gap 307;

[0043] Drill feed sub 40, connecting shaft 401, second end shaft portion 402, third end shaft portion 403, connecting groove 4031;

[0044] Guide mechanism or guide sub 5, fourth housing 51, output shaft 52, first end shaft portion 521, connecting groove 522, radial bearing assembly 53, axial thrust bearing assembly 54, eccentric straightening vane 55;

[0045] Drill bit 6, first flow hole 61;

[0046] Information transmission module 7, tool face angle measurement module 71, signal line 72, attitude measurement module 73;

[0047] First signal sub 8. DETAILED DESCRIPTION

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. Example 1

[0049] A flexible drilling tool with automatic drill feed, see Figure 1 .

[0050] like Figure 1 As shown, the drill feed sub includes a drill feed sub 1, which is provided with a hollow thrust piston 2. The thrust piston 2 includes a push rod portion 21 and a connecting joint portion 22. Four first sealing rings 23 are provided between the outer peripheral wall of the push rod portion 21 and the inner wall of the drill feed sub 1. The push rod portion 21 is able to move axially within the drill feed sub 1. A first sealing ring is provided between the outer wall of the push rod portion and the inner wall of the drill feed sub; a second sealing ring is provided between the spacer ring and the inner wall of the drill feed sub or the outer wall of the push rod portion.

[0051] In this embodiment, two annular cavities 3 are provided between the outer wall of the push rod portion 21 and the inner wall of the drill delivery sub 1, and a spacer ring 31 is provided in each annular cavity 3. In this embodiment, the spacer ring 31 is threadedly connected to the outer wall of the push rod portion 21, and a second sealing ring 32 is provided between the spacer ring 31 and the inner wall of the drill delivery sub 1. Therefore, the inner wall of the drill delivery sub 1, the outer wall of the push rod portion 21 and the spacer ring 31 can isolate a low-pressure cavity 33 in the annular cavity 3. The drill delivery sub 1 is provided with a first through hole 34 connecting the low-pressure cavity 33 and the outside, so that the hydraulic pressure in the low-pressure cavity 33 is consistent with that on the outside of the drill delivery sub 1.

[0052] Of course, in other embodiments, the spacer ring may also be connected to the inner wall of the drill feed sub by threading. In this case, the second sealing ring is arranged between the spacer ring and the outer wall of the push rod portion.

[0053] In this embodiment, Figure 1 The inner wall of the drill feed sub 1 on the middle right side, the outer wall of the push rod part 21 and the spacer ring 31 further isolate a high-pressure chamber 35 in the annular cavity 3. The push rod part 21 is provided with a second through hole 36 connecting the high-pressure chamber 35 and the push rod part 21, so that the high-pressure chamber 35 is hydraulically consistent with the inner side of the push rod part 21.

[0054] During the drilling process, the outside of the drill sub 1 is filled with low-pressure liquid, while the inside of the push rod part 21 is filled with high-pressure liquid. Therefore, the hydraulic pressure in the high-pressure chamber 35 is greater than the hydraulic pressure in the low-pressure chamber 33, forcing the spacer ring 31 to be thrust to the right (on the side of the low-pressure chamber), so that the thrust piston 2 can apply axial thrust to the right, thereby pushing the drilling tool forward.

[0055] In this embodiment, due to Figure 1 The annular cavity 3 on the left side is located at the end of the push rod portion 21. The space on the left side of the annular cavity 3 on the left side of the spacer ring 31 is directly connected to the inside of the push rod portion 21. Therefore, Figure 1 The spacer ring 31 on the left side of the center is also subjected to a rightward thrust, further prompting the thrust piston 2 to apply an axial thrust to the right.

[0056] The drill feed sub 1 in this embodiment is a hollow cylindrical structure connected by multiple short sleeves. By arranging the multiple short sleeves to be connected, the interior of the drill feed sub 1 has the required structure and the various components of the drill feed sub are easily assembled together.

[0057] Specifically, such as Figure 1As shown, in this embodiment, the drill delivery short section 1 includes two connecting sleeves 11, and hollow connectors are connected at both ends of the connecting sleeves 11, specifically including a first connector 12-1, a second connector 12-2 and a third connector 12-3. In this embodiment, the first connector 12-1 is connected between the two connecting sleeves 11, and the second connector 12-2 and the third connector 12-3 are respectively connected to the corresponding ends of the two connecting sleeves 11. The front port and the rear port of the connecting sleeve 11 are both tapered threaded ports, and the corresponding ends of the first connector 12-1, the second connector 12-2 and the third connector 12-3 are matching tapered threaded joints, so that the two connecting sleeves 11, the first connector 12-1, the second connector 12-2 and the third connector 12-3 are correspondingly connected to form the drill delivery short section 1, and the annular cavity 33 is located between the inner wall of the connecting sleeve 11, the outer wall of the thrust rod 21 and the end face of the corresponding connector.

[0058] like Figure 1 As shown, the rear end of the drill feed sub 1 is provided with a hollow drill feed joint 4. When in use, the drill feed sub is serially connected to a drilling tool, with the third connector 12-3 and the drill feed joint 4 serving as connectors. The drill feed joint 4 is provided with a connecting structure 41 for mounting the connecting joint portion 22. In this embodiment, the connecting joint portion 22 is a tapered head, and the connecting structure 41 has a corresponding tapered shape. The connecting joint portion is directly mounted within the connecting structure 41. When the push rod portion 21 is forced to move axially within the drill feed sub 1, the connecting joint portion 22 can apply a rightward axial thrust to the drill feed joint 4.

[0059] In this embodiment, the drill feed sub 4 and the second connector 12-2 are designed and assembled separately, not integrally formed. The connector portion 22 is directly connected to the drill feed sub 4 via threads. At the same time, the drill feed sub 4 and the second connector 12-2 are provided with interlocking tooth structures. During the raising of the drilling tool, the weight of the lower drilling tool is transferred from the drill feed sub 4 via the push rod portion 21 to the spacer ring 31, which is suspended from the drill feed sub, completing the force transmission. During the lowering process, the drilling pressure applied from above is directly transmitted to the drill feed sub 4 via the connector of the drill feed sub 1, forcing the drilling tool forward.

[0060] During support pressure application, the drill sub 1's connector and the drill feed connector 4 are not in close contact, hindering the transmission of WOB. Under the action of high-pressure drilling fluid, the thrust piston generates axial thrust, pushing the drill feed connector forward to complete the pressurization. During the pressurization process, the drill feed sub and the spacer ring or limit ring jointly limit the axial displacement of the thrust piston until the drill feed sub 1 and the drill feed connector shoulder are in close contact, at which point WOB transmission is achieved. Example 2

[0061] A flexible drilling tool with automatic drill feed, see Figure 2 .

[0062] like Figure 2 As shown, compared with Example 1, the drill delivery sub 1 of this embodiment includes a connecting sleeve 11 and two connecting heads, which are a fourth connecting head 12-4 and a fifth connecting head 12-5. The fourth connecting head 12-4 and the fifth connecting head 12-5 are connected to both ends of the connecting sleeve 11 through a threaded structure.

[0063] In addition, compared with Example 1, this embodiment provides an annular cavity 3 in the drill delivery sub 1, and the thrust piston 2 in this embodiment is shorter. A spacer ring 31 is provided at the end of the push rod portion 21 of the thrust piston 2. The spacer ring 31 is located in the annular cavity 3. A second sealing ring 32 is provided between the spacer ring 31 and the inner wall of the connecting sleeve 11. An annular groove is provided on the outer wall of the spacer ring 31, and the second sealing ring 32 is provided in the annular groove. A low-pressure cavity 33 is located on the right side of the spacer ring 31 in the annular cavity 3. A first through hole 34 connected to the low-pressure cavity 33 is provided on the connecting sleeve 11. When high-pressure liquid is introduced into the drill delivery sub 1, the spacer ring 31 is driven to move right, driving the thrust piston 2 to move right.

[0064] Compared with Example 1, since this embodiment only has one spacer ring 31, the thrust to the right received by the thrust piston 2 is smaller. However, the drill feed short section in this embodiment is shorter. When it is connected in series in the drilling tool, the turning radius of the drilling tool at the drill feed short section position is smaller. Example 3

[0065] A flexible drilling tool with automatic drill feed, see Figure 3 .

[0066] like Figure 3 As shown, compared with Example 1, the drill delivery short section 1 in this embodiment includes a connecting sleeve 11, and the left and right sides of the connecting sleeve 11 are respectively connected to connecting heads, namely the seventh connecting head 12-7 and the sixth connecting head 12-6, wherein the right end of the connecting sleeve 11 is provided with a tapered threaded joint, and the left side of the sixth connecting head 12-6 is correspondingly provided with a tapered threaded port, so that the sixth connecting head 12-6 is threadedly connected to the connecting sleeve 11; the right end of the seventh connecting head 12-7 is provided with a universal transmission mechanism, so that the seventh connecting head 12-7 can be deflected by a certain angle in any direction relative to the connecting sleeve 11, the universal transmission mechanism includes a spherical joint 12-7-1 connected to the internal thread of the seventh connecting head 12-7, and a first ball head seat 12-7-2 and a second ball head seat 12-7-3 provided in the cylindrical port at the left end of the connecting sleeve 11, and the first ball head seat 12-7-2 and the second ball head seat 12-7-3 are threadedly connected to the cylindrical port at the left end of the connecting sleeve 11.

[0067] In this embodiment, a spacer ring 31 is provided on the outer wall of the end of the push rod portion 21 of the thrust piston 2, and a limit ring 37 is provided at intervals. The spacer ring 31 and the limit ring 37 are connected to the outer wall of the push rod portion 21 through a threaded structure. The spacer ring 31 and the limit ring 37 are arranged in the annular cavity 3 in the drill delivery short section 1. A first through hole 34 is provided on the connecting sleeve 11, so that a low-pressure cavity 33 is isolated on the right side of the annular cavity 3, and the limit ring 37 is located in the low-pressure cavity 33.

[0068] When the spacer ring 31 is pushed to the right, the thrust piston 2 moves to the right, and the limit ring 37 can be blocked on the step surface inside the sixth connector 12-6, preventing the spacer ring 31 from moving to the right side of the first through hole 34 and causing pressure loss inside the drill feed sub 1.

[0069] In this embodiment, the connecting joint part 22 at the right end of the thrust piston 2 is a ball head, and the connecting structure 41 in the drill delivery joint 4 is a cylindrical cavity. The connecting joint part 22 is assembled in the connecting structure 41 through a combined ball seat. The combined ball seat includes a third ball head seat 22-1 and a fourth ball head seat 22-2. The third ball head seat 22-1 and the fourth ball head seat 22-2 are connected to the connecting structure 41 through a threaded structure. Therefore, the connecting joint part 22 can rotate a certain angle with the drill delivery joint 4.

[0070] It can be seen that, compared with Example 1, the drill delivery sub in this embodiment can not only apply axial thrust to the drilling tool, but also has a turning function, so that the turning radius of the drilling tool is smaller. Example 4

[0071] A flexible drilling tool with automatic drill feed, see Figures 4 to 9 .

[0072] like Figure 4 and Figure 5 As shown, the automatic drill string flexible drilling tool includes a rigid drill string 10 and a flexible section mounted at the front end of the rigid drill string 10. The rigid drill string 10 is located in the main wellbore M, and the flexible section is located in the branch wellbore N. The main wellbore M is a vertical wellbore, and the branch wellbore N is a curved wellbore. The rigid drill string 10 is used to apply weight on bit (WOB) to the flexible section. WOB refers to the forward drilling pressure of the automatic drill string flexible drilling tool in the wellbore. The flexible section can bend to drill the curved branch wellbore.

[0073] The flexible section includes multiple sections of guide power subs 20, multiple sections of articulated subs 30, and multiple sections of drill feed subs 40 in Example 1. The drill feed subs 40 are connected in series at any position between the guide power subs 20. Adjacent guide power subs 20 and drill feed subs 40, as well as adjacent guide power subs 20, are connected via articulated subs 30. In this embodiment, the drill feed subs 40 are not arranged adjacent to each other.

[0074] The steering power sub 20 is used to apply power to the rotation of the automatic drill feeding flexible drilling tool. Each joint sub 30 can achieve a certain angle range of turning, so the entire flexible section can turn, so the flexible section can be set in the branch wellbore N.

[0075] Specifically, such as Figure 6 and Figure 7 As shown, each joint short section 30 includes a first shell 301 and a second shell 302, and a universal ball shaft 303 is provided in the first shell 301 and the second shell 302. The rear end of the universal ball shaft 303 is located in the first shell 301, and the front end is located in the second shell 302. Ball heads 3031 are provided at both the front and rear ends of the universal ball shaft 303 for connecting the power short sections 20 on the front and rear sides.

[0076] The front and rear ends of the first shell 301 are conical interfaces, and the front end of the second shell 302 is correspondingly provided with a conical head, so that the end of the second shell 302 can be inserted into the port of the first shell 301, and a first gap 304 for turning is provided between the rear end of the first shell 301 and the corresponding front end of the second shell 302. The first gap 304 is an annular space, and a sealing ring is provided in the first gap 304, including a third sealing ring 3041 and a fourth sealing ring 3042, so that the first gap 304 is sealed to prevent the leakage of the high-pressure liquid medium circulating inside, and also to prevent the external hydraulic fluid from entering the first shell 301 and the second shell 302 when drilling. At the same time, the first shell 301 can turn a certain angle relative to the second shell 302.

[0077] A ball socket 305 is provided within the second housing 302, and the rear end of the second housing 302 is spherical and matches the ball socket 305, allowing the second housing 302 to swing smoothly along the first housing 301. Due to the first gap 304, when the second housing 302 turns relative to the first housing 301, one side of the third sealing ring 3041 and the fourth sealing ring 3042 can be compressed and deformed. As a result, the first and second housings 301 and 302 can turn within a certain angle range. Because the flexible section has multiple joint segments 30, each joint segment 30 can turn a certain angle, giving the flexible section as a whole a large turning range.

[0078] The first signal sub 8 is equipped with a tool face angle measurement module 71, which transmits information to the information transmission module 7 via a signal line 72. The steering power sub is equipped with an attitude measurement module 73, which transmits near-bit attitude information to the information transmission module 7 via a signal line 72. The information transmission module 7 is electrically connected to the mud pulser and can control the pulser to send signals to the surface.

[0079] like Figure 8As shown, each guide power sub 20 described in this embodiment includes a third housing 201 , and the front and rear ends of the third housing 201 can be connected to the corresponding first housing 301 and second housing 302 by means of threads.

[0080] Furthermore, each guide power short section 20 is provided with a power shaft 202, and a connecting groove 2021 is provided at both ends of the power shaft 202. The ball head 3031 at the end of the universal ball shaft is installed in the connecting groove 2021 through a universal ball key 2022. The universal ball key 2022 is connected to the connecting groove 2021 through a pin structure, a threaded socket or a tooth, and is used to transmit torque between the ball head 3031 and the connecting groove 2021.

[0081] Since the universal ball joint 33 is arranged inside the first shell 31 and the second shell 32, and its two ends are installed in the connecting groove 221 on the adjacent power shaft 22 by the ball head 331 through the universal ball key 222, when the adjacent power shaft 22 is deflected, the universal ball joint 303 completes the transmission of drilling power.

[0082] like Figure 9 As shown, the guide mechanism or guide sub 5 described in this embodiment includes a fourth housing 51, an output shaft 52 is provided in the fourth housing 51, and the drill bit 6 is integrally provided at the front end of the output shaft 52 or connected to the output shaft 52 through a thread.

[0083] The rear end of the fourth housing 51 is threadedly connected to the second housing 302 of the adjacent joint sub. The output shaft 52 includes a first end shaft portion 521 at the rear end. A connecting groove 522 is provided at the distal end of the first end shaft portion 521. The ball head 3031 of the universal ball joint adjacent to the output shaft 52 is correspondingly connected to the connecting groove 522, thereby connecting the guide mechanism or guide sub 5 to the flexible section. It is understood that the front end of the rigid drill string 10 is threadedly connected to the rear end of the first housing of the corresponding joint sub, which will not be described in detail here.

[0084] like Figure 6As shown, a connecting shaft 401 is provided within the drill feed sub 40. A second end shaft portion 402 and a third end shaft portion 403 are provided at either end of the connecting shaft 401. The connecting shaft 401 is threadedly connected to the second end shaft portion 402 or connected via a torque transmission groove, key, teeth, or a toothed recess. The second end shaft portion 402 and the third end shaft portion 403 are correspondingly threadedly connected or connected via a torque transmission groove, key, teeth, or a toothed recess. The other end of the third end shaft portion 403 is provided with a connecting groove 4031. The corresponding ball head 3031 within the joint sub is rotatably disposed in the connecting groove 4031. The drill feed connector 4 and the third connector 12-3 at both ends of the drill feed sub 40 are respectively threadedly connected to the ports of the first housing 301 of the joint sub on both sides, so that the front and rear ends of the drill feed sub 40 are connected to the joint sub on both sides. In this embodiment, there is at least one axial displacement between the second end shaft portion 402, the third end shaft portion 403, and the connecting shaft 401 that satisfies the torque transmission condition.

[0085] During construction, the flexible section of the automatic drill feeding flexible drilling tool is connected and transmitted to the well by the rigid drill string 10. The rigid drill string 10 can transmit the drilling pressure required for drilling to the flexible section. The power shaft 202 in each power short section 20 of the automatic drill feeding flexible drilling tool, the universal ball shaft 303 in each joint short section 30, the output shaft 52 in the guide mechanism or the guide short section 5, the connecting shaft 401 in each drill feeding short section 40, the second end shaft portion 402, and the third end shaft portion 403 are connected in sequence.

[0086] The drill bit 6 is installed at the front end of the output shaft 52, and the rigid drill string 10, each guide power short section 20, each joint short section 30, each drill feed short section 40, the guide mechanism or the guide short section 5 and the drill bit 6 are provided with a connecting flow channel, which is used to provide a flow channel for the drilling circulating medium.

[0087] Because the automatic drill feed flexible drilling tool is equipped with multiple articulated subs 30 and multiple power subs 20, each power sub 20 can provide independent torque. Therefore, while meeting the drilling power requirements, the articulated subs 30 and the power sub 20 are relatively short, significantly shortening the rigid section length of the overall drilling tool. In oil and gas development, the articulated subs 30 can be used to deliver the drill to a high-curvature branch wellbore, or the automatic drill feed flexible drilling tool can be delivered to a high-curvature branch well section to achieve branch well drilling operations, thereby enabling drilling in small curvature radius wellbores that are difficult to access with conventional power drilling tools.

[0088] In addition, since the automatic drill feeding flexible drilling tool is provided with multiple drill feeding subs 40, each drill feeding sub 40 can apply axial thrust to the drilling tool, and can effectively cope with the support pressure phenomenon during the drilling process.

[0089] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0090] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A flexible drilling tool with automatic drill feeding, characterized by: The present invention relates to a drilling tool according to claim 1, wherein the drill bit is provided with a plurality of drill feed short sections and a joint short section series, wherein the joint short section series includes a plurality of joint short sections, and the joint short sections include a joint structure for deflectable mutual connection; the drill feed short section includes a combined cylinder, which generates axial thrust under the action of hydraulic force to push the drill bit forward; when the automatic drilling flexible drilling tool includes a plurality of drill feed short sections, the drill feed short sections are connected by a joint structure; the drill feed short sections and the joint short sections are connected by a joint structure; the drill bit is arranged at the lower end of the drill feed short section or the joint short section; at least one drill feed short section is arranged at the lower half of the automatic drilling flexible drilling tool; the distance between the deflection points of the joint structures on both sides of the drill feed short section is between 1-5 times the diameter of the drill bit, and the distance between the deflection point of the joint structure in the joint short section and the deflection point of the adjacent joint structure is between 0.5-4 times the diameter of the drill bit; The drill feed sub is provided with a thrust piston, which includes a push rod portion and a connecting joint portion; at least one annular cavity is provided between the push rod portion and the inner wall of the drill feed sub, and a spacer ring is provided in the annular cavity, the spacer ring being connected to the inner wall of the drill feed sub or the outer wall of the push rod portion; the inner wall of the drill feed sub, the outer wall of the push rod portion and the spacer ring separate a low-pressure cavity and a high-pressure cavity in the annular cavity, and the drill feed sub is provided with a first through hole connecting the low-pressure cavity and the outside; A hollow drill delivery joint is provided at the rear end of the drill delivery short section, and a connecting structure for installing the connecting joint part is provided in the drill delivery joint. The connecting joint part is assembled in the connecting structure. When the push rod part moves axially in the drill delivery short section, the connecting joint part can apply thrust to the drill delivery joint.

2. The automatic drill feed flexible drilling tool according to claim 1, characterized in that: The automatic drill feeding flexible drilling tool comprises a plurality of drill feeding subs.

3. The automatic drill feeding flexible drilling tool according to claim 1, characterized in that: The drill feed joint and the drill feed sub are integrally formed as a housing, and the housing is divided into two relatively movable but non-detachable parts by a closed continuous curved gap, and the axial displacement of the thrust piston is limited by the gap; Or the drill feeding joint and the drill feeding short section are designed and combined separately, the connecting joint is directly connected and fixed to the drill feeding joint through threads, and the axial displacement of the thrust piston is jointly limited by the drill feeding short section joint and the spacer ring or limit ring.

4. The automatic drill feed flexible drilling tool according to claim 1, characterized in that: The inner wall of the drill feed sub, the outer wall of the push rod part and the spacer ring further isolate a high-pressure chamber in the annular chamber, and the push rod part is provided with a second through hole connecting the high-pressure chamber and the push rod part.

5. The automatic drill feeding flexible drilling tool according to claim 1, characterized in that: The drill feed sub comprises at least one connecting sleeve, the front end and / or rear end of the connecting sleeve being connected to a hollow connector, and the annular cavity being located between the inner wall of the connecting sleeve, the outer wall of the thrust rod and the corresponding end face of the connector.

6. The automatic drill feed flexible drilling tool according to claim 1, characterized in that: It also includes a guide power sub and / or a drill bit installed at the front end of the joint sub series. The drill feed sub is connected in series at any position in the joint sub series to cooperate with the guide power sub to complete the guided drilling. Each joint sub includes a first shell and a second shell connected front and back, and the first shell can be turned at a certain angle relative to the second shell; the steering power sub is any tool or combination of tools that can achieve the steering function and provide bottom hole power for drilling; Communicating flow channels are provided in the joint short sections, the drill feed short sections, the guide power short sections and the drill bit.

7. The automatic drill feed flexible drilling tool according to claim 6, characterized in that: The connecting shaft inside the drill delivery sub is a hollow cylindrical structure, and its second end shaft portion and third end shaft portion are both provided with threaded or toothed connecting grooves to be connected to the adjacent power shaft or output shaft. When relative displacement occurs between the drill delivery sub joint and the connecting joint portion, in order not to affect the torque transmission at both ends of the connecting shaft, the straight section of the connecting shaft body must meet the thrust piston stroke, and the axial displacement between the second end shaft portion and the third end shaft portion should also meet the axial displacement during the axial torque transmission process to avoid jamming and causing the drill delivery sub to fail.

8. The automatic drill feed flexible drilling tool according to claim 7, characterized in that: The front end of the first shell of the joint short section is correspondingly inserted into the rear end of the second shell, and a first gap for turning is provided between the front end of the first shell and the corresponding rear end of the second shell, and a sealing ring is provided in the first gap; a universal ball shaft is provided in the first shell and the second shell, one end of the universal ball shaft is correspondingly located in the first shell, and the other end is correspondingly located in the second shell.

9. The automatic drill feed flexible drilling tool according to claim 1, characterized in that: It also includes a rigid drill string and a flexible section installed at the front end of the rigid drill string. The rigid drill string is hollow, the flexible section is installed at the front end of the rigid drill string, and the rigid drill string is used to apply bit pressure to the flexible section.

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