A trajectory control system for a build-up section of a horizontal well with ultra-short radius

Abstract

The application discloses a kind of ultra-short radius horizontal well build-up section trajectory control systems, belong to oil and gas exploitation equipment technical field.The system includes cable drill rod, engineering parameter receiving short section, unilateral bending flexible motor, engineering parameter transmitting short section and drill bit connected in sequence.Unilateral bending flexible motor is made of multiple flexible units in series, each flexible unit includes ball head, shell, stator, rotor, output shaft and flexible shaft, by the one-way articulation of ball head and shell and the sliding fit of limiting block and limiting groove, limit flexible unit only bending in single direction, form plane circular arc trajectory, avoid the generation of helical three-dimensional curve trajectory.Drilling fluid drives rotor rotation through the drilling fluid passage of flexible unit, drives drill bit drilling.The application controls build-up section trajectory accurately, significantly reduces the frictional resistance of drill rod and well wall, improves drill bit effective load, extends horizontal section drilling depth, improves oil layer drilling rate and oil and gas recovery.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas exploitation equipment, and particularly relates to a trajectory control system for build-up section of ultra-short radius horizontal well. BACKGROUND

[0002] As an important means for developing low-permeability oil reservoirs and shallow oil reservoirs, the ultra-short radius horizontal well technology has been widely used in recent years. By drilling an ultra-short radius horizontal well in the oil reservoir, the contact area of the oil reservoir can be significantly increased, thereby improving the oil and gas recovery rate. The build-up section is a transition section connecting the vertical section and the horizontal section in the horizontal well. By adjusting the drilling assembly and directional control technology, the well trajectory is bent at a predetermined angle (usually from 0° to 90° gradually), and finally enters the horizontal state.

[0003] At present, the build-up section drilling of the ultra-short radius horizontal well mainly relies on the ultra-short radius flexible drill pipe. This drill pipe has multi-degree-of-freedom bending capability and can flexibly adjust the direction in a complex well trajectory. However, due to this multi-degree-of-freedom bending characteristic, the trajectory of the build-up section is not a simple planar circular arc, but a spiral three-dimensional curve. This spiral trajectory not only increases the frictional resistance between the drill pipe and the well wall, but also causes the effective load transmitted to the drill bit to decrease sharply, thereby seriously affecting the drilling depth of the ultra-short radius flexible drill pipe in the horizontal section. Specifically, the spiral three-dimensional curve trajectory causes the drill pipe to move more complexly in the well, increases the contact area and frictional resistance between the drill pipe and the well wall, and the increased frictional resistance not only reduces the drilling efficiency of the drill bit, but also can cause the drill pipe to be worn out or even broken prematurely. In addition, due to the reduction of the effective load, the drilling depth of the drill bit in the horizontal section is limited, thereby reducing the drilling rate of the reservoir and affecting the oil and gas recovery rate.

[0004] Therefore, how to effectively control the actual drilling trajectory of the build-up section of the ultra-short radius horizontal well, reduce the frictional resistance between the drill pipe and the well wall, and improve the effective load of the drill bit has become a key problem to be solved in the current ultra-short radius horizontal well technology. SUMMARY

[0005] The purpose of the present application is to provide a trajectory control system for build-up section of ultra-short radius horizontal well to solve the problems existing in the prior art and effectively control the actual drilling trajectory of the build-up section of the ultra-short radius horizontal well, so as to reduce the frictional resistance between the drill pipe and the well wall and improve the effective load of the drill bit.

[0006] To achieve the above purpose, the present application provides the following scheme:

[0007] The present application provides a trajectory control system for build-up section of ultra-short radius horizontal well, comprising a wired drill pipe, an engineering parameter receiving short section, a single-sided bending flexible motor, an engineering parameter transmitting short section and a drill bit connected in sequence.

[0008] The single-side bending flexible motor comprises a plurality of sequentially connected flexible units, each of which comprises a shell, a stator, a rotor, an output shaft and a flexible shaft, the stator is fixed in the shell, the rotor is fixedly connected with the output shaft, the output shaft is in rotational fit with the shell, and one end of the flexible shaft is fixedly connected with the output shaft; the flexible unit closest to the engineering parameter receiving sub is a first flexible unit, and each of the flexible units other than the first flexible unit is a second flexible unit, each of the second flexible units further comprises a ball head, the ball head is hollow, arranged outside the shell and connected with the shell; a drilling fluid channel is formed in each of the flexible units, and the drilling fluid channels of two adjacent flexible units are communicated.

[0009] The shell of the first flexible unit is fixedly connected with the engineering parameter receiving sub; in any two adjacent flexible units, the flexible unit close to the cable drill rod is a proximal flexible unit, and the other flexible unit is a distal flexible unit, the flexible shaft in the proximal flexible unit passes through the ball head in the distal flexible unit and is connected with the output shaft in the distal flexible unit, the ball head in the distal flexible unit is unidirectionally hinged with the shell in the proximal flexible unit, and the unidirectional rotation directions of all the ball heads are the same; the flexible shaft in the flexible unit closest to the engineering parameter transmitting sub passes through the engineering parameter transmitting sub and is fixedly connected with the drill bit.

[0010] Preferably, a plurality of limiting blocks are arranged on the ball head, a limiting groove corresponding to each of the limiting blocks on the ball head in the distal flexible unit is arranged on the shell in the proximal flexible unit, and the limiting blocks and the corresponding limiting grooves are in sliding fit along the unidirectional rotation direction.

[0011] Preferably, a first spherical arc surface is arranged on the side of the limiting block away from the ball head, the side of the limiting block close to the ball head is fixedly connected with the ball head, and the remaining side walls of the limiting block are planes; a second spherical arc surface corresponding to the first spherical arc surface on the corresponding limiting block is arranged on the limiting groove, and the first spherical arc surface and the corresponding second spherical arc surface are in sliding fit.

[0012] Preferably, the output shaft is in rotational fit with the shell through a bearing, a bearing seat corresponding to the bearing is arranged on the shell, and the bearing is installed on the bearing seat.

[0013] Preferably, a plurality of liquid passing holes are arranged on the bearing seat, and the drilling fluid channel comprises the liquid passing holes.

[0014] Preferably, the shell comprises an end cover, an upper shell and a lower shell, the end cover is connected with one end of the upper shell, the lower shell is connected with the other end of the upper shell, the stator, the rotor and the output shaft are arranged in the upper shell, the flexible shaft passes through the lower shell, and the limiting groove is arranged on the lower shell.

[0015] Preferably, a locking sleeve is further arranged, the ball head is threadedly connected with the locking sleeve, and the locking sleeve is connected with the end cover.

[0016] Preferably, a first sealing ring is arranged between the end cover and the upper shell, and a second sealing ring is arranged between the upper shell and the lower shell.

[0017] Preferably, a plurality of positioning bosses are arranged on the end cover, a plurality of positioning grooves corresponding to the positioning bosses are arranged on the upper shell, and the positioning bosses can be embedded in the corresponding positioning grooves.

[0018] Preferably, an adjusting sleeve is arranged on the bearing seat, and the flexible unit further comprises a pressing ring arranged on the rotor.

[0019] The present application has the following technical effects relative to the prior art:

[0020] The super-short radius horizontal well build-up section trajectory control system of the present application realizes accurate control of the trajectory of the super-short radius horizontal well build-up section by sequentially connecting the wired drill pipe, the engineering parameter receiving sub, the single-side bending flexible motor, the engineering parameter transmitting sub and the drill bit, not only avoids the disturbance of the stratum caused by the rotation of the flexible drill pipe itself, but also ensures that the actual drilling trajectory of the build-up section is a planar circular arc due to the single-side bending characteristics of the drill pipe, improves the random three-dimensional curve trajectory of the build-up section caused by the omnidirectional bending of the flexible drill pipe, effectively reduces the frictional resistance between the drill pipe and the well wall, improves the effective load of the drill bit, and thus significantly improves the drilling efficiency of the super-short radius horizontal well and the oil and gas recovery rate.

[0021] Further, the engineering parameter transmitting sub collects data and wirelessly transmits the data to the engineering parameter receiving sub, the receiving sub transmits the data to the ground processing system through the wired drill pipe, the drilling trajectory of the build-up section can be monitored online, it can be quickly judged whether the target reservoir is entered, and it is beneficial to adjust the drilling process, thereby saving the drilling period and the drilling cost.

[0022] Further, the single-side bending flexible motor comprises a plurality of sequentially connected flexible units, each of which comprises a ball head, a shell, a stator, a rotor, an output shaft and a flexible shaft. This design enables each flexible unit to rotate and each flexible unit except the first flexible unit to deflect to the same direction, so that the single-side bending flexible motor as a whole can be single-side bent, flexibly adjust the direction in a complex wellbore trajectory, reduce the formation of spiral three-dimensional curve trajectory and reduce frictional resistance. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort based on these drawings.

[0024] Figure 1 Structure diagram of the trajectory control system for the build-up section of the ultra-short radius horizontal well of the present application Figure 1 ;

[0025] Figure 2 Structure diagram of the trajectory control system for the build-up section of the ultra-short radius horizontal well of the present application Figure 2 ;

[0026] Figure 3 Structure diagram of the single-side bending flexible motor in the trajectory control system for the build-up section of the ultra-short radius horizontal well of the present application

[0027] Figure 4 Structure diagram of the ball head in the trajectory control system for the build-up section of the ultra-short radius horizontal well of the present application

[0028] Figure 5 Structure diagram of the lower shell in the trajectory control system for the build-up section of the ultra-short radius horizontal well of the present application

[0029] Figure 6 Structure diagram of the upper shell in the trajectory control system for the build-up section of the ultra-short radius horizontal well of the present application

[0030] Figure 7 Structure diagram of the end cover in the trajectory control system for the build-up section of the ultra-short radius horizontal well of the present application

[0031] Figure 8 Connection diagram of the ball head and the lower shell in the trajectory control system for the build-up section of the ultra-short radius horizontal well of the present application Figure 1 ;

[0032] Figure 9 Connection diagram of the ball head and the lower shell in the trajectory control system for the build-up section of the ultra-short radius horizontal well of the present applicationFigure 2 ;

[0033] Figure 10 The figure is a schematic diagram of the flow direction of the drilling fluid in the flexible unit;

[0034] Figure 11 The figure is a schematic diagram of the structure of the bearing seat in the application;

[0035] In the figure: 1, cable drill pipe; 2, engineering parameter receiving sub; 3, single-sided bending flexible motor; 4, engineering parameter transmitting sub; 5, drill bit; 11, ball head; 12, end cover; 13, locking sleeve; 14, upper shell; 15, adjusting sleeve; 16, bearing; 17, bearing seat; 18, pressing ring; 19, stator; 110, rotor; 111, output shaft; 112, flexible shaft; 113, first sealing ring; 114, lower shell; 115, second sealing ring; 121, end cover positioning surface; 122, positioning boss; 113, limiting stopper; 112, ball head positioning surface; 141, limiting groove; 142, positioning groove. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the application.

[0037] The purpose of the application is to provide a super-short radius horizontal well build-up section trajectory control system to solve the problems in the prior art, effectively control the actual drilling trajectory of the super-short radius horizontal well build-up section, reduce the frictional resistance between the drill pipe and the well wall, and improve the effective load of the drill bit.

[0038] In order to make the above-mentioned purposes, characteristics and advantages of the application more obvious and easy to understand, the application will be further described in detail below with reference to the drawings and specific embodiments.

[0039] As shown in Figures 1 to 11 The embodiment provides a super-short radius horizontal well build-up section trajectory control system, which comprises cable drill pipes 1, engineering parameter receiving subs 2, single-sided bending flexible motors 3, engineering parameter transmitting subs 4 and drill bits 5 connected in sequence.

[0040] The single-side bending flexible motor 3 comprises a plurality of sequentially connected flexible units, each of which comprises a ball head 11, a shell, a stator 19, a rotor 110, an output shaft 111 and a flexible shaft 112, the ball head 11 is hollow, arranged outside the shell and connected with the shell, the stator 19 is fixedly arranged in the shell, the rotor 110 is fixedly connected with the output shaft 111, the output shaft 111 is rotationally matched with the shell, and one end of the flexible shaft 112 is fixedly connected with the output shaft 111; a drilling fluid channel is formed in each flexible unit, and the drilling fluid channels of two adjacent flexible units are communicated;

[0041] The flexible unit closest to the engineering parameter receiving sub 2 is a first flexible unit, and the other flexible units except the first flexible unit are second flexible units, the first flexible unit does not comprise the ball head 11, and the shell of the first flexible unit is fixedly connected with the engineering parameter receiving sub 2, the connection mode ensures the stability and continuity of the system, and the movement of the drill pipe in the wellbore is more stable, and unnecessary friction and wear are reduced; in any two adjacent flexible units, the flexible unit close to the wired drill pipe 1 is a proximal flexible unit, and the other flexible unit is a distal flexible unit, the flexible shaft 112 in the proximal flexible unit penetrates through the ball head 11 in the distal flexible unit and is connected with the output shaft 111 in the distal flexible unit, and after the flexible shaft 112 in the proximal flexible unit penetrates through the ball head 11 in the distal flexible unit, a remaining space is ensured in the hollow part of the ball head 11 except the flexible shaft 112, to serve as part of the drilling fluid channel, to ensure the smooth flow of the drilling fluid, the ball head 11 in the distal flexible unit is one-way hinged with the shell in the proximal flexible unit, and the one-way rotation directions of all the ball heads 11 are the same; the flexible shaft 112 in the flexible unit closest to the engineering parameter transmitting sub 4 penetrates through the engineering parameter transmitting sub 4 and is fixedly connected with the drill bit 5.

[0042] It is worth mentioning that the engineering parameter receiving sub 2 and the engineering parameter transmitting sub 4 are commercially available products well known to those skilled in the art, and both are hollow to facilitate the passage of cables, drilling fluids and the like, so the specific structure and working principle of the engineering parameter receiving sub 2 and the engineering parameter transmitting sub 4 will not be described in detail in this embodiment.

[0043] In the optional scheme of this embodiment, preferably, two limiting blocks 113 are arranged on the ball head 11, and a limiting groove 141 corresponding to the limiting block 113 on the ball head 11 in the distal flexible unit is arranged on the shell in the proximal flexible unit, and the limiting block 113 and the corresponding limiting groove 141 are slidingly matched in the above-mentioned one-way rotation direction (see Figure 8 and Figure 9 The limiting and sliding matching design ensures that the two adjacent flexible units can only rotate relative to each other in a single direction, realizes that the single-side bending flexible motor 3 can only bend in a single direction, avoids unnecessary swinging and friction, and improves the stability and reliability of the system.

[0044] In the optional scheme of the embodiment, preferably, the side of the limiting block 113 away from the ball head 11 is a first spherical surface, the side of the limiting block 113 close to the ball head 11 is fixedly connected with the ball head 11, and the remaining side wall of the limiting block 113 is a plane; the limiting recess 141 is provided with a second spherical surface corresponding to the first spherical surface on the corresponding limiting block 113, the first spherical surface and the corresponding second spherical surface are in sliding fit, and the area of the second spherical surface is greater than that of the first spherical surface, the first spherical surface and the second spherical surface are in close contact, and the design of the first spherical surface and the second spherical surface makes the sliding between the limiting block 113 and the limiting recess 141 more smooth, reduces the frictional resistance, and improves the response speed and accuracy of the system.

[0045] In the optional scheme of the embodiment, preferably, the output shaft 111 is in rotary fit with the shell through the bearing 16, the shell is provided with a bearing seat 17 corresponding to the bearing 16, and the bearing 16 is installed on the bearing seat 17, which ensures the stable rotation of the output shaft 111, reduces the friction and wear, and improves the service life and reliability of the system.

[0046] In the optional scheme of the embodiment, preferably, as shown in Figure 11 the bearing seat 17 is provided with three through liquid holes 171 uniformly distributed in the circumferential direction, in the embodiment, the through liquid hole 171 is an arc-shaped hole; the drilling fluid channel includes the through liquid hole, the through liquid hole 171 communicates the upper and lower sides of the bearing seat 17, and the flow path of the drilling fluid in a single flexible unit is as shown in Figure 10 the design of the through liquid hole 171 ensures that the drilling fluid can smoothly pass through each flexible unit in turn, reduces the resistance of the drilling fluid flow, drives the rotation of the rotor 110 in each flexible unit, and improves the drilling efficiency.

[0047] In the optional scheme of the embodiment, preferably, the shell includes an end cover 12, an upper shell 14 and a lower shell 114, the end cover 12 is connected with one end of the upper shell 14, the lower shell 114 is connected with the other end of the upper shell 14, the stator 19, the rotor 110 and the output shaft 111 are all arranged in the upper shell 14, the flexible shaft 112 passes through the lower shell 114, and the limiting recess 141 is arranged on the lower shell 114, and this split design facilitates the assembly and maintenance of the system, and improves the operability and reliability of the system.

[0048] In an optional scheme of the embodiment, preferably, the locking sleeve 13 is further included, the ball head 11 is threadedly connected with the locking sleeve 13, the locking sleeve 13 is connected with the end cover 12, and the locking sleeve 13 is arranged to ensure the close connection between the ball head 11 and the shell, reduce the looseness and friction, and improve the stability and reliability of the system; the ball head 11 and the end cover 12 are positioned and matched by the end cover positioning surface 121 and the ball head positioning surface 112.

[0049] In an optional scheme of the embodiment, preferably, the first sealing ring 113 is arranged between the end cover 12 and the upper shell 14, and the second sealing ring 115 is arranged between the upper shell 14 and the lower shell 114, and the arrangement of the first sealing ring 113 and the second sealing ring 115 ensures the sealing property of the shell, prevents the drilling fluid from leaking, and improves the safety and reliability of the system.

[0050] In an optional scheme of the embodiment, preferably, the two positioning bosses 122 are arranged on the end cover 12, the positioning recesses 142 corresponding to the positioning bosses 122 are arranged on the upper shell 14, the positioning bosses 122 can be embedded in the corresponding positioning recesses 142, and the design of the positioning bosses 122 and the positioning recesses 142 ensures the accurate positioning between the end cover 12 and the upper shell 14, reduces the assembly error, and improves the precision and reliability of the system.

[0051] In an optional scheme of the embodiment, preferably, the adjusting sleeve 15 is arranged on the bearing seat 17, the arrangement of the adjusting sleeve 15 ensures the stable installation and adjustment of the bearing 16, reduces the friction and wear, and improves the service life and reliability of the system; the flexible unit further includes the compression ring 18 installed on the rotor 110, the compression ring 18 is installed by matching with the rotor 110, can effectively fix the position of the rotor 110, prevents the rotor 110 from being axially or radially deviated during high-speed rotation, the fixing action ensures the stable operation of the rotor 110 in the shell, reduces the vibration and friction caused by the deviation of the rotor 110, and thus improves the operation stability and service life of the system.

[0052] The specific working principle of the trajectory control system for the build-up section of the ultra-short radius horizontal well in the embodiment is as follows:

[0053] The engineering parameter transmitting short section 4 collects the inclination, azimuth, gamma and other engineering parameters near the drill bit 5, and wirelessly transmits them to the engineering parameter receiving short section 2. The engineering parameter receiving short section 2 transmits the obtained data to the wired drill pipe 1. The wired drill pipe 1 transmits the data to the ground processing system through the cable embedded in the drill pipe. The operator will obtain the real-time drilling trajectory of the build-up section, perform online monitoring, compare the design path, and make timely adjustments. At the same time, the operator will quickly determine whether the target reservoir is entered according to the obtained formation gamma data, so as to adjust the subsequent drilling assembly and drilling technology. After the drilling fluid enters the flexible unit, the rotor 110 is driven to rotate, the drilling fluid energy inside the drill pipe is converted into torque, the output shaft 111 and the flexible shaft 112 are driven to rotate, the series structure of multiple flexible units realizes multi-stage superposition of torque, and finally the torque is transmitted to the drill bit 5.

[0054] The embodiment realizes the planar circular arc trajectory control of the build-up section of the ultra-short radius horizontal well by the directional control of the unilateral bending flexible motor 3, the trajectory constraint of the limiting mechanism and the closed-loop feedback of the engineering parameter short section. The core lies in changing the multi-degree-of-freedom bending of the flexible drill pipe in the prior art. The unilateral bending of the unilateral bending flexible motor 3 converts the spiral trajectory into a planar trajectory, thereby significantly reducing the frictional resistance and improving the effective load, and finally solving the problem of insufficient drilling depth in the prior art.

[0055] The principle and implementation mode of the present application are described by applying specific examples in the present application. The above embodiment is only used to help understand the method of the present application and its core idea; at the same time, for those skilled in the art, according to the idea of the present application, the specific implementation mode and application range will be changed. In conclusion, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A trajectory control system for the build-up section of an ultra-short radius horizontal well, characterized in that: It includes a cable drill rod, an engineering parameter receiving sub, a single-sided bending flexible motor, an engineering parameter launching sub, and a drill bit, which are connected in sequence. The single-sided bending flexible motor includes multiple flexible units connected in sequence. Each flexible unit includes a housing, a stator, a rotor, an output shaft, and a flexural shaft. The stator is fixed inside the housing, the rotor is fixedly connected to the output shaft, the output shaft is rotatably coupled to the housing, and one end of the flexural shaft is fixedly connected to the output shaft. The flexible unit closest to the engineering parameter receiving section is the first flexible unit, and each of the other flexible units is a second flexible unit. Each second flexible unit also includes a ball head, which is hollow, disposed outside the housing, and connected to the housing. Each flexible unit has a drilling fluid channel, and the drilling fluid channels of two adjacent flexible units are connected. The housing of the first flexible unit is fixedly connected to the engineering parameter receiving section; in any two adjacent flexible units, the flexible unit closer to the cabled drill rod is the proximal flexible unit, and the other flexible unit is the distal flexible unit. The flexural shaft in the proximal flexible unit passes through the ball joint in the distal flexible unit and is connected to the output shaft in the distal flexible unit. The ball joint in the distal flexible unit is unidirectionally hinged to the housing in the proximal flexible unit, and all the ball joints rotate in the same unidirectional direction. The flexural shaft in the flexible unit closest to the engineering parameter launching section passes through the engineering parameter launching section and is fixedly connected to the drill bit. The ball head is provided with a plurality of limiting blocks, and the housing in the proximal flexible unit is provided with limiting grooves corresponding one-to-one with the limiting blocks on the ball head in the distal flexible unit. The limiting blocks and the corresponding limiting grooves slide in the unidirectional rotation direction. The side of the limiting block away from the ball head is a first spherical arc surface, and the side of the limiting block close to the ball head is fixedly connected to the ball head. The remaining sidewalls of the limiting block are flat. The limiting groove is provided with a second spherical arc surface corresponding to the first spherical arc surface on the corresponding limiting block. The first spherical arc surface and the corresponding second spherical arc surface slide in the same manner.

2. The trajectory control system for the ultra-short radius horizontal well build-up section according to claim 1, characterized in that: The output shaft is rotatably coupled to the housing via a bearing, and a bearing seat is provided on the housing corresponding to the bearing, and the bearing is mounted on the bearing seat.

3. The trajectory control system for the ultra-short radius horizontal well build-up section according to claim 2, characterized in that: The bearing housing is provided with a plurality of fluid passage holes, and the drilling fluid channel includes the fluid passage holes.

4. The trajectory control system for the ultra-short radius horizontal well build-up section according to claim 1, characterized in that: The housing includes an end cover, an upper housing, and a lower housing. The end cover is connected to one end of the upper housing, and one end of the lower housing is connected to the other end of the upper housing. The stator, the rotor, and the output shaft are all disposed in the upper housing. The flexural shaft passes through the lower housing, and the limiting groove is disposed on the lower housing.

5. The trajectory control system for the ultra-short radius horizontal well build-up section according to claim 4, characterized in that: It also includes a locking sleeve, the ball head being threadedly connected to the locking sleeve, and the locking sleeve being connected to the end cap.

6. The trajectory control system for the ultra-short radius horizontal well build-up section according to claim 4, characterized in that: A first sealing ring is provided between the end cap and the upper housing, and a second sealing ring is provided between the upper housing and the lower housing.

7. The trajectory control system for the ultra-short radius horizontal well build-up section according to claim 4, characterized in that: The end cap is provided with a plurality of positioning protrusions, and the upper housing is provided with positioning grooves that correspond one-to-one with the positioning protrusions, and the positioning protrusions can be fitted into the corresponding positioning grooves.

8. The trajectory control system for the ultra-short radius horizontal well build-up section according to claim 2, characterized in that: An adjusting sleeve is provided on the bearing housing, and the flexible unit also includes a pressure ring installed on the rotor.

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