A high build rate drilling assembly with a rearward deflection variable gauge stabilizer

Abstract

The present application belongs to the technical field of oilfield drilling engineering, and particularly relates to a high build-up rate drilling tool assembly device of a post-positioned deflection variable-diameter centralizer, comprising a centralizing mechanism, a drilling tool mechanism and a connecting and locking mechanism; the drilling tool mechanism comprises a drill bit and a single-bend screw rod, the two ends of the single-bend screw rod are connected with the centralizing mechanism and the drilling tool mechanism respectively; the centralizing mechanism comprises a centralizing rod, a deflection variable-diameter passage is arranged through the centralizing rod in the axial direction, a relief mechanism and a plurality of centralizing units are arranged on the side surface of the centralizing rod; a bypass hole is arranged in the centralizing rod, one end of the bypass hole is connected with the deflection variable-diameter passage, and the other end of the bypass hole is connected with the relief mechanism. The technical scheme can increase the sliding build-up rate, reduce the sliding well section and improve the drilling efficiency. The technical invention can solve the problem of difficult directional build-up in large-size inclined well sections, can be popularized and applied in the directional construction of horizontal wells, directional wells and branch horizontal wells, and has a wide market application prospect.

Description

Technical Field

[0001] This invention belongs to the field of oilfield drilling engineering technology, specifically relating to a high build-up rate drill string assembly device with a rear-mounted deflection diameter stabilizer. Background Technology

[0002] With the proliferation of horizontal wells, directional wells, and branched horizontal wells, especially large-diameter horizontal wells, ensuring build-up efficiency during drilling operations has become increasingly difficult. During drilling, the configuration of directional drilling tools, their structural shape, drilling process parameters, and formation geological parameters all influence the build-up rate, with the directional drilling tool assembly having the greatest impact. High build-up rate drilling tool assemblies can reduce the slip ratio during directional drilling and increase the rate of penetration, which is of great significance for further promoting efficient composite directional drilling technology.

[0003] The term "large borehole" refers to a wellbore with a diameter greater than 241mm, generally including diameters such as φ311mm, φ346mm, φ394mm, and φ444.5mm. Many problems often arise during the construction of large boreholes. For exploration horizontal wells, to account for the uncertainties of exploration operations and ensure safe and smooth exploration, a large three-section wellbore structure is generally adopted, with a reserved layer of technical casing. For example, the gas exploration horizontal wells in Changqing Oilfield generally adopt a wellbore structure of φ444.5mm drill bit × φ339.7mm surface casing + φ311.2mm drill bit × φ244.5mm technical casing + φ215.9mm drill bit × φ139.7mm production casing. In deviated sections, a 311.2mm drill bit is used. The large borehole size in deviated sections results in low directional drilling efficiency with large-diameter screw drills, and directional drilling in deviated sections suffers from pressure build-up, tool face instability, and low mechanical drilling rates. Especially in the early stages of deviated well sections, the sliding ratio needs to reach over 80% for sections with an inclination of 0-30 degrees and over 50% for sections with an inclination of 30-60 degrees to meet trajectory control requirements. In the Changqing Oilfield gas exploration horizontal wells with a large φ311.2mm borehole size and low screw drill build-up rate, it is crucial to prevent under-inclination from causing passive trajectory control. Based on actual drilling data analysis, the PDC build-up rate is low in the small-inclination section of the φ311.2mm borehole, especially due to difficulties in initiating inclination at the build-up point, easily leading to under-inclination. This is typically addressed by changing the drill bit, increasing the angle of the single-bend screw drill, and increasing the length of the sliding section, sacrificing mechanical drilling rate to complete the large-inclination borehole build-up.

[0004] For bottom screw drill string assemblies with the same screw bend angle under different wellbore conditions, for example, the build-up rate of the bottom screw drill string assembly in the build-up section of a well with a diameter of φ444.5mm is lower than that of the bottom screw drill string assembly in the build-up section of a well with a diameter of φ311.2mm, especially in the initial build-up section. Improving the build-up rate of large-diameter wells and increasing the ratio of composite drilling to sliding drilling, thereby significantly increasing the drilling rig speed, is of great significance to drilling operations. Summary of the Invention

[0005] The purpose of this invention is to propose a high build-up rate drilling tool assembly with a rear-mounted deflector and diameter stabilizer, so as to effectively solve the problems of slow drilling speed and high sliding footage ratio in the construction of large-diameter directional wells.

[0006] This invention is achieved by adopting the following technical solution:

[0007] A high build-up rate drill bit assembly with a rear-mounted deflection diameter stabilizer is characterized by comprising a stabilizer mechanism, a drill bit mechanism, and a connecting locking mechanism; the drill bit mechanism includes a drill bit and a single-bend screw rod, the drill bit being mounted on one end of the single-bend screw rod, and the other end of the single-bend screw rod being connected to the stabilizer mechanism via the connecting locking mechanism; the stabilizer mechanism includes a stabilizer rod, with a deflection diameter changing channel extending through it axially, and a pressure relief mechanism and several stabilizer units provided on the side of the stabilizer rod; a bypass channel is provided inside the stabilizer rod, one end of which is connected to the deflection diameter changing channel, and the other end of which is connected to the pressure relief mechanism.

[0008] Preferably, the biased variable diameter channel includes an inlet connector, a first variable diameter channel, an eccentric variable diameter channel and a second variable diameter channel connected axially in sequence, and the flow area of ​​the eccentric variable diameter channel is less than the flow area of ​​the first variable diameter channel and less than the flow area of ​​the second variable diameter channel.

[0009] Preferably, the pressure relief mechanism includes a bypass valve body and a pressure relief groove radially formed on the side of the straightening rod, the bottom of the pressure relief groove being connected to the first diameter changing channel; one end of the bypass channel being connected to the pressure relief groove, and the other end being connected to the second diameter changing channel; the bypass valve body is embedded in the pressure relief groove and is used to control the bypass channel to be connected to and closed with the first diameter changing channel.

[0010] Preferably, the bypass valve body includes a connecting body, a spring, and a sealing ball; the connecting body is fixedly connected to the straightening rod, and the two ends of the spring are respectively connected to the sealing ball and the connecting body.

[0011] Preferably, the straightening rod is provided with two straightening units, and the two straightening units are located at the same axial height position of the straightening rod.

[0012] Preferably, the included angle between the central axes of the two straightening units is α, and 60°≤α≤120°.

[0013] Preferably, the straightening unit includes an installation groove, a sliding sleeve, and a straightening block; the installation groove is radially opened along the straightening rod, the sliding sleeve is fixedly installed in the installation groove and tightly fits the groove wall; the straightening block is located inside the sliding sleeve, sealingly fits the inner wall of the sliding sleeve, and is slidably connected to the sliding sleeve for limiting.

[0014] Preferably, sealing rings are embedded on the outer side of the sliding sleeve and the outer side of the straightening block.

[0015] Preferably, the axial cross-section of the straightening block is convex, and a limiting protrusion is provided at one end of the sliding sleeve near the top. The limiting protrusion cooperates with the convex structure of the straightening block to prevent the limiting protrusion from disengaging from the sliding sleeve.

[0016] Preferably, the straightening unit further includes a clamping screw, which is screwed to the straightening rod, and the nut of the clamping screw clamps the sliding sleeve.

[0017] Preferably, the connection locking mechanism includes a connection locking sleeve, a connector female buckle for connecting the straightening rod, and a connection male buckle for connecting the single-bend screw; the connection male buckle and the connection female buckle are fastened together by the connection locking sleeve.

[0018] The beneficial technical effects of this invention are as follows:

[0019] This technical solution addresses the construction of large-diameter directional wells by proposing a high-build-rate drilling tool assembly with a rear-mounted deflector and variable-diameter stabilizer. The assembly combines a stabilizer, a single-bend screw, and a drill bit, and can be used for both sliding and combined drilling operations. With the assistance of the stabilizer, stable directional build-up is achieved during sliding drilling, reducing the proportion of sliding drilling and increasing the rate of penetration. In summary, this technical solution increases the sliding build-up rate, reduces the sliding well section, and improves drilling efficiency. This invention solves the problem of difficult directional build-up in large-diameter deviated well sections and can be widely applied in directional construction of horizontal wells, directional wells, and branch horizontal wells, with broad market prospects.

[0020] This technical solution proposes a high build-up rate drill string assembly with a rear-mounted deflection variable diameter stabilizer. The stabilizer, combined with a single-bend screw and drill bit, enables controlled downhole directional drilling from the surface. Specifically, a deflection variable diameter channel is designed inside the stabilizer to utilize hydraulic forces. This allows for direct observation and adjustment of the single-bend screw direction from the surface. During sliding drilling, differential pressure provides support; when transitioning from sliding drilling to composite drilling, automatic pressure relief eliminates the need for tripping back into the well. Since existing drilling operations inherently require fluid injection into the drill string, the structure and working principle of this stabilizer are compatible with existing drilling technologies, allowing it to be integrated into existing drilling equipment and technology. The design is ingenious, and the operation is simple and convenient.

[0021] For safe operation, this technical solution uses differential pressure to provide support, reducing the impact on the drill string; it automatically releases pressure when the support force is too large; when the pump stops rotating, the upright blocks are retracted to reduce the risk of stuck drill bit and facilitate tripping in and out of the drill string. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the axial cross-sectional structure of the drill string assembly.

[0023] Figure 2 This is a radial cross-sectional view of the drill string assembly.

[0024] Figure 3 A schematic diagram of the axial cross-sectional structure of the connecting lock;

[0025] Figure 4 This is a schematic diagram illustrating the application principle of the drill string assembly.

[0026] In the picture:

[0027] 1. Drill bit; 2. Single-bend screw; 3. Bending support point; 4. Straightening mechanism; 4.1 Straightening rod; 4.2 Pressure relief mechanism; 4.21 Bypass channel; 4.22 Pressure relief groove; 4.23 Connector; 4.24 Spring; 4.25 Sealing ball; 4.3 Straightening unit; 4.31 Mounting groove; 4.32 Sliding sleeve; 4.33 Straightening block; 4.34 Sealing ring; 4.35 Clamping screw; 4.4 Offset diameter changing channel; 4.41 Liquid inlet connector; 4.42 First diameter changing channel; 4.43 Eccentric diameter changing channel; 4.44 Second diameter changing channel; 5. Connecting locking mechanism; 5.1 Connecting locking sleeve; 5.2 Connector female thread; 5.3 Connecting male thread; 6. Fluid flow direction. Detailed Implementation

[0028] To make the purpose, technical solution and advantages of the invention clearer, the technical solution of the invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the invention, but not all embodiments.

[0029] Therefore, the following detailed description of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0030] Example 1

[0031] This embodiment discloses a high build-up rate drill string assembly (hereinafter referred to as the drill string assembly) with a rear-mounted deflection diameter stabilizer, as a basic implementation scheme of the present invention, such as... Figure 1As shown, the system includes a straightening mechanism 4, a drilling tool mechanism, and a connecting locking mechanism 5. The drilling tool mechanism includes a drill bit 1 and a single-bend screw 2. The drill bit 1 is installed at one end of the single-bend screw 2, and the other end of the single-bend screw 2 is connected to the straightening mechanism 4 through the connecting locking mechanism 5. The straightening mechanism 4 includes a straightening rod 4.1, and a deflection diameter changing channel 4.4 is provided through the straightening rod 4.1 along its axial direction. A pressure relief mechanism 4.2 and several straightening units 4.3 are provided on the side of the straightening rod 4.1. A bypass channel 4.21 is provided inside the straightening rod 4.1. One end of the bypass channel 4.21 is connected to the deflection diameter changing channel 4.4, and the other end of the bypass channel 4.21 is connected to the pressure relief mechanism 4.2.

[0032] like Figure 4 As shown, the above-mentioned drill string assembly is used in drilling operations. The specific usage method and principle are as follows:

[0033] Drill bit 1 and straightening mechanism 4 are installed at both ends of single-bend screw 2, respectively, so that the internal structures of straightening mechanism 4, single-bend screw 2, and drill bit 1 are sequentially sealed and connected, completing the initial assembly of the drill string. After adjusting the bending direction of single-bend screw 2 to be consistent with the straightening direction of straightening mechanism 4, the straightening mechanism 4 and single-bend screw 2 are fixed relative to each other by connecting locking mechanism 5, completing the assembly of the drill string. According to the drilling construction design requirements, the assembled drill string is used for compound drilling and sliding drilling operations. In the compound drilling state, the drill string rotates as a whole under the control of the surface equipment, while single-bend screw 2 drives drill bit 1 to rotate under the action of internal fluid (drilling fluid). When directional drilling is required, it enters the sliding drilling state, that is, the drill string stops rotating as a whole, and single-bend screw 2 continues to drive drill bit 1 to rotate under the action of internal fluid (drilling fluid), while straightening mechanism 4 cooperates with single-bend screw 2 to directionally create an directional drilling direction in the target direction.

[0034] In actual construction sites, as the drilling depth increases, drilling equipment such as drill collars, downhole tools, and drill pipes are continuously connected and stacked behind the centralizing mechanism 4. The connection and application of these drilling equipment is a standard practice in drilling engineering (and will not be elaborated here). Conventional directional drilling is divided into sliding drilling and combined drilling depending on the drilling method. In sliding drilling, the rotary table or top drive is locked (which can be understood as "cutting off" the overall rotational control of the drill collars, centralizing mechanism 4, single-bend screw 2, and drill bit 1 from the surface rotary drive equipment), and only the single-bend screw 2 drives the drill bit 1 to rotate to cut the formation. In sliding drilling, directional drilling operations can be performed with the help of the centralizing mechanism 4. In the combined drilling state, the drilling of the single-bend screw 2 (i.e., the single-bend screw 2 drives the drill bit 1 to rotate) is combined with the rotary table drilling (i.e., the rotary table is unlocked, and the ground rotation drive equipment controls the overall synchronous rotation of the drill collar, the straightening mechanism 4, the single-bend screw 2 and the drill bit 1, etc.). At this time, the bending direction of the single-bend screw 2 is uncertain, so it is impossible to create an skew.

[0035] Furthermore, based on the above structure, the directional tilting in the target direction by the straightening mechanism 4 in conjunction with the single-bend screw 2 includes the following steps:

[0036] Adjust the drilling face posture according to the target direction to prepare for directional operation;

[0037] Hydraulic force is injected into the drill string through ground equipment (such as by pumping high-pressure drilling fluid into the drill fluid pump), causing the centralizing block 4.33 of the centralizing mechanism 4 to extend radially under hydraulic operation until it supports the well wall;

[0038] The supporting force of the straightening block 4.33 on the well wall is F2, and the well wall provides the straightening block 4.33 with the same and opposite supporting force, F1=F2;

[0039] Under the action of the counter-support force F2, the bending support point 3 of the single-bend screw 2 is used as the point of force exertion, so that a force F3 is generated at the high force point of the drill bit 1, and then the sliding drilling operation begins.

[0040] Furthermore, once the sliding drilling operation is completed (i.e., the current directional drilling task is completed), the drill string is switched to the composite drilling state. Specifically, the switch can be completed by unlocking the rotary table. After the switch, the straightening block 4.33 of the straightening mechanism 4 retracts into the straightening rod 4.1 under the action of rotational force to withdraw the supporting force on the well wall.

[0041] Example 2

[0042] This embodiment discloses a high build-up rate drill bit assembly device with a rear-mounted deflection diameter stabilizer. As a basic implementation of the present invention, it includes a stabilizer mechanism 4, a drill bit mechanism, and a connecting locking mechanism 5. The drill bit mechanism includes a drill bit 1 and a single-bend screw 2. The drill bit 1 is installed at one end of the single-bend screw 2, and the other end of the single-bend screw 2 is connected to the stabilizer mechanism 4 through the connecting locking mechanism 5. The stabilizer mechanism 4 includes a stabilizer rod 4.1, with a deflection diameter channel 4.4 extending through the stabilizer rod 4.1 axially. A pressure relief mechanism 4.2 and several stabilizer units 4.3 are provided on the side of the stabilizer rod 4.1. A bypass channel 4.21 is opened inside the stabilizer rod 4.1. One end of the bypass channel 4.21 is connected to the deflection diameter channel 4.4, and the other end of the bypass channel 4.21 is connected to the pressure relief mechanism 4.2.

[0043] The biased variable diameter channel 4.4 includes a fluid inlet connector 4.41, a first variable diameter channel 4.42, an eccentric variable diameter channel 4.43, and a second variable diameter channel 4.44 connected axially in sequence. The flow area of ​​the eccentric variable diameter channel 4.43 is less than the flow area of ​​the first variable diameter channel 4.42 and less than the flow area of ​​the second variable diameter channel 4.44. Based on this structure, since the flow areas of each channel are different, the hydraulic pressure in each channel is also different. When the bypass channel 4.21 is closed, the centralizing unit 4.3 extends to provide support. At the same time, the flow rate and discharge of the injected fluid (drilling fluid) can be controlled by surface equipment (such as a water pump system), thereby controlling the magnitude of the hydraulic pressure. Furthermore, based on this biased variable diameter channel 4.4 structure, to achieve the utilization and control of the hydraulic pressure, it is best to position the pressure relief mechanism 4.2 and the centralizing unit 4.3 at the corresponding positions of the first variable diameter channel 4.42.

[0044] Furthermore, the pressure relief mechanism 4.2 includes a bypass valve body and a pressure relief groove 4.22 radially formed on the side of the stabilizer 4.1. The bottom of the pressure relief groove 4.22 is connected to the first variable diameter channel 4.42. One end of the bypass channel 4.21 is connected to the pressure relief groove 4.22, and the other end is connected to the second variable diameter channel 4.44. The bypass valve body is embedded in the pressure relief groove 4.22 and is used to control the connection and closure of the bypass channel 4.21 and the first variable diameter channel 4.42. Based on this structure, when the drill bit is in a sliding drilling state, the bypass valve body is in a closed state, ensuring that the hydraulic pressure in the first variable diameter channel 4.42 increases. When the drill bit is in a combined drilling state, due to the rotation of the stabilizer, the bypass valve body opens under the action of centrifugal force, and part of the fluid in the first variable diameter channel 4.42 flows directly into the second variable diameter channel 4.44 through the bypass channel 4.21 to achieve the purpose of pressure relief.

[0045] Furthermore, based on the aforementioned working requirements of the bypass valve body, the bypass valve body can adopt the following structure: the bypass valve body includes a connecting body 4.23, a spring 4.24, and a sealing ball 4.25; the connecting body 4.23 is fixedly connected to the centralizing rod 4.1, and the two ends of the spring 4.24 are respectively connected to the sealing ball 4.25 and the connecting body 4.23. Thus, when the drill bit is in the sliding drilling state, the sealing ball 4.25, under the action of the spring 4.24, blocks the pressure relief groove 4.22 and the first diameter changing channel 4.42. When the drill bit is in the combined drilling state, the sealing ball 4.25, under the action of centrifugal force, leaves its original blocking position and compresses the spring 4.24. At this time, the first diameter changing channel 4.42, the pressure relief groove 4.22, and the bypass channel 4.21 are sequentially connected.

[0046] Example 3

[0047] This embodiment discloses a high build-up rate drill bit assembly device with a rear-mounted deflection diameter stabilizer. As a basic implementation of the present invention, it includes a stabilizer mechanism 4, a drill bit mechanism, and a connecting locking mechanism 5. The drill bit mechanism includes a drill bit 1 and a single-bend screw 2. The drill bit 1 is installed at one end of the single-bend screw 2, and the other end of the single-bend screw 2 is connected to the stabilizer mechanism 4 through the connecting locking mechanism 5. The stabilizer mechanism 4 includes a stabilizer rod 4.1, with a deflection diameter channel 4.4 extending through the stabilizer rod 4.1 axially. A pressure relief mechanism 4.2 and several stabilizer units 4.3 are provided on the side of the stabilizer rod 4.1. A bypass channel 4.21 is opened inside the stabilizer rod 4.1. One end of the bypass channel 4.21 is connected to the deflection diameter channel 4.4, and the other end of the bypass channel 4.21 is connected to the pressure relief mechanism 4.2.

[0048] Among them, such as Figure 2 As shown, two straightening units 4.3 are provided on the straightening rod 4.1, and the two straightening units 4.3 are located at the same axial height position on the straightening rod 4.1. Furthermore, the included angle between the central axes of the two straightening units 4.3 is α, and 60°≤α≤120°. Thus, the two straightening units 4.3 cooperate to support the well wall, making the straightening operation of the straightening mechanism 4 more stable.

[0049] Furthermore, the centralizing unit 4.3 includes an installation groove 4.31, a sliding sleeve 4.32, and a centralizing block 4.33. The installation groove 4.31 is radially opened along the centralizing rod 4.1. The sliding sleeve 4.32 is fixedly installed in the installation groove 4.31 and tightly fits against the groove wall of the installation groove 4.31. The centralizing block 4.33 is located inside the sliding sleeve 4.32, sealingly fitting against the inner wall of the sliding sleeve 4.32, and is limited and slidably connected to the sliding sleeve 4.32. Based on this structure, the working principle of the centralizing unit 4.3 is as follows: When the hydraulic force at the corresponding local position in the variable diameter channel increases, the centralizing block 4.33 extends radially outward under the action of the hydraulic force to support the well wall. A mutual supporting force is generated between the centralizer and the well wall. After the pressure is released through the pressure relief mechanism 4.2, the hydraulic force decreases, the centralizing block 4.33 retracts radially, and the supporting force is withdrawn.

[0050] Example 4

[0051] This embodiment discloses a high build-up rate drill bit assembly device with a rear-mounted deflection diameter stabilizer. As a basic implementation of the present invention, it includes a stabilizer mechanism 4, a drill bit mechanism, and a connecting locking mechanism 5. The drill bit mechanism includes a drill bit 1 and a single-bend screw 2. The drill bit 1 is installed at one end of the single-bend screw 2, and the other end of the single-bend screw 2 is connected to the stabilizer mechanism 4 through the connecting locking mechanism 5. The stabilizer mechanism 4 includes a stabilizer rod 4.1, with a deflection diameter channel 4.4 extending through the stabilizer rod 4.1 axially. A pressure relief mechanism 4.2 and several stabilizer units 4.3 are provided on the side of the stabilizer rod 4.1. A bypass channel 4.21 is opened inside the stabilizer rod 4.1. One end of the bypass channel 4.21 is connected to the deflection diameter channel 4.4, and the other end of the bypass channel 4.21 is connected to the pressure relief mechanism 4.2.

[0052] The straightening rod 4.1 is equipped with two straightening units 4.3, and the two straightening units 4.3 are located at the same axial height position of the straightening rod 4.1. Furthermore, the included angle between the central axes of the two straightening units 4.3 is α, and 60°≤α≤120°.

[0053] Furthermore, the straightening unit 4.3 includes a mounting groove 4.31, a sliding sleeve 4.32, and a straightening block 4.33; the mounting groove 4.31 is radially opened along the straightening rod 4.1, the sliding sleeve 4.32 is fixedly installed in the mounting groove 4.31 and is tightly fitted with the groove wall of the mounting groove 4.31; the straightening block 4.33 is located inside the sliding sleeve 4.32, is sealed and fitted with the inner wall of the sliding sleeve 4.32, and is limited and slidably connected with the sliding sleeve 4.32.

[0054] Furthermore, sealing rings 4.34 are embedded on the outer side of the sliding sleeve 4.32 and the outer side of the straightening block 4.33 to prevent leakage of the straightening mechanism 4.

[0055] Furthermore, the axial cross-section of the straightening block 4.33 is convex. The sliding sleeve 4.32 is provided with a limiting protrusion near the top. The limiting protrusion, in conjunction with the convex structure of the straightening block 4.33, is used to prevent the limiting protrusion from disengaging from the sliding sleeve 4.32, so as to prevent the straightening block 4.33 from disengaging from the straightening rod 4.1 under hydraulic action, which would cause the straightening mechanism 4 to leak.

[0056] Furthermore, the straightening unit 4.3 also includes a clamping screw 4.35, which is screwed to the straightening rod 4.1. The nut of the clamping screw 4.35 clamps the sliding sleeve 4.32 to prevent the sliding sleeve 4.32 from detaching from the straightening rod 4.1 under hydraulic action, which would cause the straightening mechanism 4 to leak.

[0057] Example 5

[0058] A high build-up rate drill bit assembly with a rear-mounted deflection diameter stabilizer is characterized by comprising a stabilizer mechanism 4, a drill bit mechanism, and a connecting locking mechanism 5; the drill bit mechanism includes a drill bit 1 and a single-bend screw 2, the drill bit 1 being mounted on one end of the single-bend screw 2, and the other end of the single-bend screw 2 being connected to the stabilizer mechanism 4 via the connecting locking mechanism 5; the stabilizer mechanism 4 includes a stabilizer rod 4.1, with a deflection diameter changing channel 4.4 extending through the stabilizer rod 4.1 axially, and a pressure relief mechanism 4.2 and several stabilizer units 4.3 provided on the side of the stabilizer rod 4.1; a bypass channel 4.21 is provided inside the stabilizer rod 4.1, one end of the bypass channel 4.21 being connected to the deflection diameter changing channel 4.4, and the other end of the bypass channel 4.21 being connected to the pressure relief mechanism 4.2.

[0059] Furthermore, the offset variable diameter channel 4.4 includes an inlet connector 4.41, a first variable diameter channel 4.42, an eccentric variable diameter channel 4.43, and a second variable diameter channel 4.44 connected axially in sequence, wherein the flow area of ​​the eccentric variable diameter channel 4.43 is less than the flow area of ​​the first variable diameter channel 4.42 and less than the flow area of ​​the second variable diameter channel 4.44. The second variable diameter channel 4.44 is also an outlet channel, and an outlet connector is provided on the outer wall of the straightening rod at its location.

[0060] Furthermore, the pressure relief mechanism 4.2 includes a bypass valve body and a pressure relief groove 4.22 radially formed on the side of the centralizing rod 4.1. The bottom of the pressure relief groove 4.22 is connected to the first variable diameter channel 4.42. One end of the bypass channel 4.21 is connected to the pressure relief groove 4.22, and the other end is connected to the second variable diameter channel 4.44. The bypass valve body is embedded in the pressure relief groove 4.22 and is used to control the connection and closure of the bypass channel 4.21 and the first variable diameter channel 4.42. The bypass valve body includes a connecting body 4.23, a spring 4.24, and a sealing ball 4.25. The connecting body 4.23 is fixedly connected to the centralizing rod 4.1, and the two ends of the spring 4.24 are respectively connected to the sealing ball 4.25 and the connecting body 4.23.

[0061] Furthermore, two straightening units 4.3 are provided on the straightening rod 4.1, and the two straightening units 4.3 are located at the same axial height position of the straightening rod 4.1. The included angle between the central axes of the two straightening units 4.3 is α, and 60°≤α≤120°.

[0062] Furthermore, the straightening unit 4.3 includes a mounting groove 4.31, a sliding sleeve 4.32, and a straightening block 4.33. The mounting groove 4.31 is radially opened along the straightening rod 4.1. The sliding sleeve 4.32 is fixedly installed in the mounting groove 4.31 and tightly fits against the groove wall of the mounting groove 4.31. The straightening block 4.33 is located inside the sliding sleeve 4.32, sealingly fitting against the inner wall of the sliding sleeve 4.32, and slidingly connected to the sliding sleeve 4.32 for limiting. Sealing rings 4.34 are embedded on the outer side of the sliding sleeve 4.32 and the outer side of the straightening block 4.33. The axial cross-section of the straightening block 4.33 is convex. A limiting protrusion is provided at the top end of the sliding sleeve 4.32. The limiting protrusion, in conjunction with the convex structure of the straightening block 4.33, is used to prevent the limiting protrusion from detaching from the sliding sleeve 4.32. The straightening unit 4.3 also includes a clamping screw 4.35, which is screwed to the straightening rod 4.1, and the nut of the clamping screw 4.35 clamps the sliding sleeve 4.32.

[0063] Furthermore, such as Figure 3 As shown, the connecting locking mechanism 5 includes a connecting locking sleeve 5.1, a connector female buckle 5.2 for connecting the straightening rod 4.1, and a connecting male buckle 5.3 for connecting the single-bend screw 2; the connecting male buckle 5.3 and the connecting female buckle are fastened together by the connecting locking sleeve 5.1.

Claims

1. A high build-up rate drill string assembly with a rear-mounted deflector diameter stabilizer, characterized in that: Includes a straightening mechanism (4), a drilling tool mechanism, and a connecting and locking mechanism (5); The drilling mechanism includes a drill bit (1) and a single-bend screw (2). The drill bit (1) is installed at one end of the single-bend screw (2), and the other end of the single-bend screw (2) is connected to the straightening mechanism (4) through a connecting locking mechanism (5). The straightening mechanism (4) includes a straightening rod (4.1), and a deflection variable diameter channel (4.4) is provided through the straightening rod (4.1) along its axial direction; a pressure relief mechanism (4.2) and several straightening units (4.3) are provided on the side of the straightening rod (4.1), and a bypass channel (4.21) is provided. The biased variable diameter channel (4.4) includes an inlet connector (4.41), a first variable diameter channel (4.42), an eccentric variable diameter channel (4.43), and a second variable diameter channel (4.44) connected axially in sequence. The flow area of ​​the eccentric variable diameter channel (4.43) is less than the flow area of ​​the first variable diameter channel (4.42) and less than the flow area of ​​the second variable diameter channel (4.44). The pressure relief mechanism (4.2) includes a bypass valve body and a pressure relief groove (4.22) radially opened along the straightening rod (4.1); the bottom of the pressure relief groove (4.22) is connected to the first diameter change channel (4.42) of the deflection diameter change channel (4.4); one end of the bypass channel (4.21) is connected to the pressure relief groove (4.22), and the other end is connected to the second diameter change channel (4.44) of the deflection diameter change channel (4.4); the bypass valve body is embedded in the pressure relief groove (4.22) and is used to control the connection and closure of the bypass channel (4.21) and the first diameter change channel (4.42); The straightening unit (4.3) is located outside the first variable diameter channel (4.42) and achieves radial expansion and contraction based on the magnitude of the hydraulic force inside the first variable diameter channel (4.42).

2. The high build-up rate drill string assembly with a rear-mounted deflector and diameter stabilizer as described in claim 1, characterized in that: The bypass valve body includes a connector (4.23), a spring (4.24), and a sealing ball (4.25); the connector (4.23) is fixedly connected to the straightening rod (4.1), and the two ends of the spring (4.24) are respectively connected to the sealing ball (4.25) and the connector (4.23).

3. The high build-up rate drill string assembly with a rear-mounted deflector and diameter stabilizer as described in claim 1, characterized in that: The straightening rod (4.1) is provided with two straightening units (4.3), and the two straightening units (4.3) are located at the same axial height position of the straightening rod (4.1).

4. A high build-up rate drill string assembly with a rear-mounted deflector and diameter stabilizer as described in claim 3, characterized in that: The included angle between the central axes of the two straightening units (4.3) is a, and 60°≤a≤120°.

5. A high build-up rate drill string assembly with a rear-mounted deflector and diameter stabilizer as described in claim 1, characterized in that: The straightening unit (4.3) includes a mounting groove (4.31), a sliding sleeve (4.32), and a straightening block (4.33). The mounting groove (4.31) is radially opened along the straightening rod (4.1). The sliding sleeve (4.32) is fixedly installed in the mounting groove (4.31) and is tightly fitted with the groove wall of the mounting groove (4.31). The straightening block (4.33) is located inside the sliding sleeve (4.32), is sealed and fitted with the inner wall of the sliding sleeve (4.32), and is limited and slidably connected with the sliding sleeve (4.32).

6. A high build-up rate drill string assembly with a rear-mounted deflector and diameter stabilizer as described in claim 5, characterized in that: A sealing ring (4.34) is embedded on the outer side of the sliding sleeve (4.32) and the outer side of the straightening block (4.33).

7. A high build-up rate drill string assembly with a rear-mounted deflector and diameter stabilizer as described in claim 5, characterized in that: The axial cross section of the straightening block (4.33) is convex. The sliding sleeve (4.32) is provided with a limiting protrusion at one end near the top. The limiting protrusion cooperates with the convex structure of the straightening block (4.33) to prevent the limiting protrusion from disengaging from the sliding sleeve (4.32).

8. A high build-up rate drill string assembly with a rear-mounted deflector and diameter stabilizer as described in claim 5, characterized in that: The straightening unit (4.3) also includes a clamping screw (4.35), which is screwed to the straightening rod (4.1), and the nut of the clamping screw (4.35) clamps the sliding sleeve (4.32).

9. A high build-up rate drill string assembly with a rear-mounted deflector and diameter stabilizer as described in claim 1, characterized in that: The connecting locking mechanism (5) includes a connecting locking sleeve (5.1), a female connector (5.2) for connecting the straightening rod (4.1), and a male connector (5.3) for connecting the single-bend screw (2); the male connector (5.3) and the female connector are fastened together by the connecting locking sleeve (5.1).

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