CN211819296U - Reverse circulation grinding and milling system for horizontal well - Google Patents

Abstract

The application provides a horizontal well reverse circulation milling system, in this system, go up conversion cavity portion and down conversion cavity portion first crossover sub and the inside conversion of second crossover sub respectively, realize circulation liquid circulation channel's change, realize the reverse circulation of circulation liquid to make the milling piece return ground along with circulation liquid smoothly, this can effectively prevent the production of accidents such as piece sticking to bore, thereby realize improving milling efficiency, reduce the construction risk. The adjusting part is arranged to effectively solve the connection of inflection points between the horizontal well section and the vertical well section, so that the circulating liquid with milling chips is prevented from being influenced by the horizontal well section, and the circulating liquid effectively returns to the ground along the vertical well section. The pressure of the pumped circulation liquid drives the hydraulic motor to normally operate in the hydraulic motor part, so that the effective rotating speed and the torque of the bottom are realized, the effective rotating torque acts on the hollow rotating shaft to drive the lower conversion cavity part to rotate, the sleeve milling work is completed, and the milling efficiency is improved.

Description

A horizontal well reverse circulation milling system

technical field

The utility model relates to the technical field of horizontal wells, in particular to a horizontal well reverse circulation milling system.

Background technique

With the deepening of oilfield development, most of the oilfields have basically entered the middle and late stages of exploitation. Some oil and water wells are produced with disease due to falling objects and casing changes, and in severe cases, oil and water wells will be scrapped. In recent years, drilling technology and production technology have gradually matured, and many highly deviated wells and horizontal wells have been continuously developed, but the supporting workover technology has not been improved. The problem is especially reflected in the horizontal drilling, grinding and milling construction operations.

In the traditional workover milling operation, the drilling tool is connected to the milling bit and then lowered into the well, and the ground equipment provides the drilling tool with rotational torque in the well, so that the milling bit can be used for milling operations. Affected by the characteristics of horizontal wells, the drilling tool is affected by the inflection point, so that most of the rotational torque provided by the surface equipment is consumed by frictional resistance, and the milling effect is not obvious.

Based on this, a way of connecting a drilling tool, a hydraulic motor and a milling bit is adopted for workover milling construction, so that the torque provided by the hydraulic motor directly acts on the top of the falling object, thereby improving the milling efficiency. Due to the use of hydraulic motor drive, the circulation mode of circulating fluid must be positive circulation mode, that is, the circulating fluid reaches the milling drill bit from the inner hole of the drilling tool through the hydraulic motor, and returns through the water hole of the milling drill bit. As a result, the chips generated during milling are carried back to the surface from between the drilling tool and the casing by the circulating fluid. Due to the influence of wear resistance, at the same time, the circulation channel changes from a small channel to a large channel, which reduces the flow rate of the circulating fluid, and the large debris cannot be returned. Returning to the ground from the well will lead to the accumulation of some debris, resulting in the jamming of the milling and drilling tools cannot be effectively dealt with, which will cause engineering accidents, and in serious cases, the oil well will be scrapped.

Utility model content

The utility model provides a horizontal well reverse circulation milling system to solve the problem of accumulation of a large amount of debris in the horizontal well in the existing workover milling construction process.

The utility model provides a horizontal well reverse circulation milling system, which comprises an upper conversion cavity part, an adjustment part, a hydraulic motor part and a lower conversion cavity part; the connecting joint is connected to the upper conversion cavity part and the hydraulic motor part; the hydraulic motor part and the lower conversion cavity part are connected by a connecting shaft;

The upper conversion cavity part comprises a rubber cylinder seat sealing pipe, a first conversion joint and a conversion center pipe whose ends are connected; a sealing rubber cylinder with a sealing sleeve is arranged on the outside of the rubber cylinder seat sealing pipe;

The end of the first conversion joint is provided with a first conversion cavity, and the first conversion cavity is communicated with the conversion center pipe;

A first conversion jacket is provided outside the end of the first conversion joint, and a first clamping cavity is formed between the first conversion jacket, the first conversion joint and the conversion center pipe;

The lower conversion cavity part includes a hollow rotating shaft and a second conversion joint connected; the end of the second conversion joint is provided with a second conversion cavity, and the second conversion cavity is connected to the hollow rotary shaft. connected;

A second conversion jacket is provided on the outer side of the connection between the hollow rotating shaft and the second conversion joint, and a second clamping cavity is formed between the second conversion jacket, the hollow rotating shaft and the second conversion joint;

The outer side of the hollow rotating shaft is provided with a centralizing sleeve, a third clamping cavity is formed between the centralizing sleeve and the hollow rotating shaft, and the second clamping cavity is communicated with the third clamping cavity.

Preferably, a fourth clamping cavity is formed between the rubber cartridge seat sealing tube and the conversion center pipe; the first clamping cavity is respectively communicated with the fourth clamping cavity and the inside of the first conversion joint.

Preferably, the adjustment part includes an adjustment sleeve, a changeover switch, and an extension pipe located outside the conversion center pipe; a switch joint is provided between the adjustment sleeve and the changeover switch;

A connecting jacket is provided on the outside of the extension pipe, and a fifth clamping cavity is formed between the connecting jacket and the transfer switch, the extension pipe, the hydraulic motor part, and the righting jacket;

A sixth clamping cavity is formed between the transfer switch and the conversion central pipe; the fifth clamping cavity and the sixth clamping cavity are communicated with each other through a flow hole.

Preferably, the outer side of the extension pipe is provided with a butt coupling.

Preferably, a switch lock ring is provided between the switch connector and the transfer switch.

Preferably, a rotating tube is provided on the outside of the hollow rotating shaft, and the rotating tube is connected with the centralizing sleeve bearing; a seventh clamping cavity is formed between the hollow rotating shaft and the rotating tube, and the seventh clamping cavity They are respectively communicated with the second clamping cavity and the third clamping cavity.

Preferably, a lower pressure cap is arranged between the end of the centralizing sleeve and the rotating tube, and a lock ring is arranged on the lower pressure cap.

Preferably, the hollow rotating shaft and the connecting shaft are connected by a connecting cap, and a deep groove ball bearing is provided at the contact point between the hollow rotating shaft, the connecting shaft and the connecting cap.

The technical solutions provided by the embodiments of the present utility model may include the following beneficial effects:

In the horizontal well reverse circulation milling system provided by the present application, the internal conversion of the first conversion joint and the second conversion joint of the upper conversion cavity and the lower conversion cavity, respectively, realizes the change of the circulating fluid circulation channel and realizes the circulation of the circulating fluid. Reverse circulation, so that the milling debris can be smoothly returned to the ground with the circulating fluid, which can effectively prevent the occurrence of accidents such as debris sticking, thereby improving the milling efficiency and reducing the construction risk. The setting of the adjustment part can effectively solve the connection at the inflection point between the horizontal well section and the vertical well section, thereby avoiding the influence of the circulating fluid with milling debris from the horizontal well section, so that it can effectively return to the surface along the vertical well section . The pressure of the pumped circulating fluid drives the hydraulic motor in the hydraulic motor part to operate normally, so as to realize the effective speed and torque of the bottom, and the effective rotational torque acts on the hollow rotating shaft, which drives the lower conversion cavity to rotate, and completes the sleeve milling process. work to improve milling efficiency.

It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not limiting of the invention.

Description of drawings

In order to illustrate the technical solutions of the present application more clearly, the accompanying drawings that need to be used in the embodiments will be briefly introduced below. Other drawings can also be obtained from these drawings.

1 is a schematic diagram of the overall structure of a horizontal well reverse circulation milling system provided by an embodiment of the present invention;

2 is a schematic structural diagram of an up-conversion cavity part provided by an embodiment of the present invention;

3 is a schematic structural diagram of an adjustment portion provided by an embodiment of the present invention;

4 is a schematic structural diagram of a down-conversion cavity part provided by an embodiment of the present invention;

Symbol means:

01-up conversion cavity part, 02-adjustment part, 03-hydraulic motor part, 04-down conversion cavity part, 05-first connection joint, 06-second connection joint, 07-connection shaft;

1-Cylinder seat sealing tube, 2-The first conversion joint, 3-Conversion center pipe, 4-Sleeve, 5-Sealing rubber cylinder, 6-The first conversion cavity, 7-The first conversion jacket, 8-The first conversion A clamping cavity, 9-Hollow rotating shaft, 10-Second conversion joint, 11-Second conversion cavity, 12-Second conversion jacket, 13-Second clamping cavity, 14-Centring sleeve, 15-Third clamping cavity , 16- the fourth clamping cavity, 17- adjusting sleeve, 18- transfer switch, 19- extension pipe, 20- switch connector, 21- connecting jacket, 22- fifth clamping cavity, 23- sixth clamping cavity, 24- Flow hole, 25-butt coupling, 26-switch lock ring, 27-rotating tube, 28-seventh clamping cavity, 29-pressing cap, 30-locking ring, 31-connecting cap, 32-deep groove ball bearing, 33 - Center tube butt coupling.

Detailed ways

Please refer to FIG. 1 . FIG. 1 shows a schematic diagram of the overall structure of a horizontal well reverse circulation milling system provided by an embodiment of the present application. As can be seen from FIG. 1 , the horizontal well reverse circulation milling system provided by the embodiment of the present application includes an upper conversion cavity part 01 , an adjustment part 02 , a hydraulic motor part 03 and a lower conversion cavity part 04 , wherein two parts of the adjustment part 02 are The ends are respectively connected to the upper conversion cavity part 01 and the hydraulic motor part 03 through the first connection joint 05 and the second connection joint 06, and the hydraulic motor part 03 and the lower conversion cavity part 04 are connected through the connection shaft 07, thereby realizing the horizontal well Assembly of parts in a reverse circulation milling system.

Specifically, as shown in FIG. 2 , the upper conversion cavity 01 is located at the top of the horizontal well reverse circulation milling system, and is the part that realizes the sealing of the casing 4 , the pumping of the circulating fluid and the pumping of the circulating fluid. The upper conversion cavity 01 in the embodiment of the present application includes a rubber cartridge seat sealing pipe 1, a first conversion joint 2 and a conversion center pipe 3, wherein the first conversion joint 2 and the ends of the conversion center pipe 3 are connected, and the conversion The central tube 3 is located inside the sealing tube 1 of the cartridge seat.

The rubber cartridge seat sealing tube 1 is used for setting the sealing rubber tube 5 of the sealing sleeve 4 , so that the sealing rubber tube 5 of the sealing sleeve 4 is provided on the outside of the rubber tube seat sealing tube 1 . Since the sealant cartridge 5 can seal the sleeve 4, the sealant cartridge 5 divides the sleeve 4 into two parts, namely the first conversion joint 2, the first conversion jacket 7 and other components located at the upper end of the sealant cartridge 5, and the parts located at the upper end of the sealant The adjustment part 02, the hydraulic motor part 03 and the lower conversion cavity part 04 at the lower end of the rubber cylinder 5.

The first conversion joint 2 is used to transfer the circulating liquid from the casing 4 to the conversion center pipe 3, and then the conversion center pipe 3 brings the circulating liquid into the adjustment part 02, the hydraulic motor part 03 and the lower conversion cavity part 04. Therefore, a certain gap exists between the first adapter 2 and the sleeve 4 . One end of the first conversion joint 2 is a hollow structure, and the other end is provided with a first conversion cavity 6, and the first conversion cavity 6 is communicated with the conversion center pipe 3, so that the circulating fluid can pass from the first conversion joint 2 to the sleeve. The gap between the pipes 4 enters the first conversion cavity 6, and then is converted into the conversion center pipe 3 to realize the reverse circulation pumping of the circulating liquid. In addition, the end of the first conversion joint 2 is provided with a first conversion jacket 7 , and a first clamping cavity 8 is formed between the first conversion jacket 7 , the first conversion joint 2 and the conversion center pipe 3 . A fourth clamping cavity 16 is formed between the rubber cartridge seat sealing tube 1 and the conversion center pipe 3 , and the first clamping cavity 8 is communicated with the fourth clamping cavity 16 and the inside of the first conversion joint 2 respectively. Therefore, after the returned circulating fluid enters the first clamping cavity 8 from the fourth clamping cavity 16 , it returns to the hollow of the first adapter 2 from the first clamping cavity 8 , and is then discharged from the first adapter 2 .

The adjustment part 02 is not only used for the connection between the horizontal well section and the vertical well section, but also for supplying liquid to the hydraulic motor part 03 . In the embodiment of the present application, the up-conversion cavity part 01 and the adjustment part 02 are connected through the first connection joint 05 . Since the adjustment part 02 is used for the connection between the horizontal well section and the vertical well section, if the length of the conversion center pipe 3 is not enough, the connection and extension can be realized by the center pipe butt coupling 34 . The length of the conversion center pipe 3 is set according to the actual situation.

Please refer to FIG. 3 . FIG. 3 shows a schematic structural diagram of the adjusting part 02 provided by the embodiment of the present application. As can be seen from FIG. 3 , the adjustment part 02 includes an adjustment sleeve 17 , a changeover switch 18 , and an extension pipe 19 located outside the switching center pipe 3 . Wherein, the adjusting sleeve 17 and the rubber cylinder seat sealing pipe 1 are connected through the first connecting joint 05 to realize the connection between the upper conversion cavity part 01 and the adjusting part 02 . The first connection joint 05 is usually arranged at the connection between the horizontal well section and the vertical well section, that is, at the inflection point. The arrangement of the first connection joint 05 can prevent the rotational torque provided by the ground equipment from being consumed by frictional resistance, thereby improving the milling effect.

A switch joint 20 is arranged between the adjustment sleeve 17 and the changeover switch 18 , and a switch lock ring 26 is arranged between the switch joint 20 and the changeover switch 18 to facilitate the opening of the changeover switch 18 . A sixth clamping cavity 23 is formed between the changeover switch 18 and the changeover central pipe 3 to facilitate the return of the circulating fluid. The outer side of the extension pipe 19 is provided with a connecting jacket 21, and a fifth clamping cavity 22 is formed between the connecting outer casing 21 and the transfer switch 18, the extension pipe 19, the hydraulic motor part 03, and the centering sleeve 14, and the fifth clamping cavity 22 is used for circulating fluid. return. The connection between the transfer switch 18 and the extension pipe 19 is provided with a flow hole 24, so that the circulating liquid enters the inside of the extension pipe 19 from the outside of the extension pipe 19, that is, the circulating liquid enters the sixth cavity through the fifth clamping cavity 22 and the flow hole 24. in the clamping cavity 23 . Further, to enhance the structural strength of the extension pipe 19 at the inflection point, a butt coupling 25 is provided on the outside of the extension pipe 19 .

The hydraulic motor part 03 can provide milling torque for the horizontal well reverse circulation milling system provided in the embodiment of the application, so as to overcome the problem that the wellhead torque cannot be transmitted to the horizontal section. The hydraulic motor part 03 in the embodiment of the present application is located in a horizontal well section, which drives the hydraulic motor in the hydraulic motor part 03 to operate normally through the pressure of the pumped circulating fluid, so as to realize the effective rotational speed and torque at the bottom, and the effective rotational torque acts on the The hollow rotating shaft 9 drives the lower conversion cavity 04 to rotate to complete the sleeve milling work.

Please refer to FIG. 4 . FIG. 4 shows a schematic structural diagram of the down-conversion cavity part 04 provided by the embodiment of the present application. As can be seen from FIG. 4 , the down conversion cavity 04 is located at the end of the horizontal well reverse circulation milling system, specifically in the horizontal well section. The lower conversion cavity part 04 is used to circulate the circulating fluid carrying the milling debris from the cavity of the milling device. The circulating fluid does not pass through the annulus of the drilling tool and the casing, and the diameter of the circulating channel does not increase much, which solves the problem of the circulating fluid carrying the grinding and milling debris. The chips return to the ground smoothly, so as to realize the process of reverse circulation milling. The lower conversion cavity 04 realizes that the circulating liquid in the central cavity flows into the casing 4 through the second conversion joint 10 to complete the flushing operation, and then brings the circulating liquid carrying the milling debris from the central cavity back to the clamping cavity of the system, Complete the return of circulating fluid.

Specifically, the lower conversion cavity 04 includes a hollow rotary shaft 9 and a second conversion joint 10 , and two ends of the hollow rotary shaft 9 are respectively connected to the connecting shaft 07 and the second conversion joint 10 . The outer side of one end of the hollow rotating shaft 9 is provided with a connecting cap 31 , and the connecting cap 31 is used to connect the hollow rotating shaft 9 and the connecting shaft 07 . In order to realize the rotation of the hollow rotating shaft 9 , a deep groove ball bearing 32 is provided at the contact point between the hollow rotating shaft 9 , the connecting shaft 07 and the connecting cap 31 .

The outer side of the hollow rotating shaft 9 is provided with a centralizing sleeve 14 and a rotating tube 27 . Wherein, the centralizing sleeve 14 and the rotating pipe 27 are partially overlapped, and the overlapping portion of the centralizing sleeve 14 and the rotating pipe 27 is connected by a bearing. The centralizing sleeve 14 is in sealing contact with the end of the connecting casing 21 , so as to realize the sealing between the connecting casing 21 , the centralizing casing 14 and the hollow rotating shaft 9 . Since the centralizing sleeve 14 is disposed on the outer side of the hollow rotating shaft 9, a third clamping cavity 15 is formed between the centralizing sleeve 14 and the hollow rotating shaft 9, and the third clamping cavity 15 is used for the return of the circulating liquid. A seventh clamping cavity 28 is formed between the hollow rotating shaft 9 and the rotating pipe 27 , and the seventh clamping cavity 28 is used for the return of the circulating liquid. In the embodiment of the present application, the third clamping cavity 15 communicates with the second clamping cavity 13 and the seventh clamping cavity 28 respectively, and the seventh clamping cavity 28 communicates with the second clamping cavity 13 and the fifth clamping cavity 22 respectively. In addition, a lower pressing cap 29 is provided between the end of the centralizing sleeve 14 and the rotating tube 27 , and a locking ring 30 is arranged on the lower pressing cap 29 .

The end of the second conversion joint 10 is provided with a second conversion cavity 11 , and the second conversion cavity 11 communicates with the hollow rotating shaft 9 , so as to realize that the circulating fluid is converted from the hollow rotating shaft 9 through the second conversion cavity 11 . Drain into casing 4. The outer side of the connection between the hollow rotating shaft 9 and the second conversion joint 10 is provided with a second conversion jacket 12 , and a second clamping cavity 13 is formed between the second conversion jacket 12 , the hollow rotary shaft 9 and the second conversion joint 10 . The clamping cavity 13 is communicated with the third clamping cavity 15 .

The circulation process of the circulating fluid in the horizontal well reverse circulation milling system provided by the embodiment of the present application is:

The circulating fluid is pumped from the casing 4 , and when passing through the horizontal well reverse circulation milling system provided in the embodiment of the present application, the circulating fluid enters between the casing 4 and the first conversion joint 2 . The circulating liquid entering between the sleeve 4 and the first conversion joint 2 enters the conversion center pipe 3 after being converted by the first conversion cavity 6 . The circulating fluid enters the hydraulic motor part 03 through the switching center pipe 3 inside the regulating part 02 . After the circulating fluid enters the hydraulic motor portion 03 , while providing power to the hydraulic motor portion 03 , the circulating fluid continues to move downward in the direction of the cavity portion 04 until it enters the interior of the hollow rotating shaft 9 . The circulating liquid inside the hollow rotating shaft 9 enters between the second conversion jacket 12 and the casing 4 after being converted by the second conversion cavity 11, and then completely enters the casing 4 to realize the reverse circulation pumping of the circulating liquid. , and then realize the flushing of the milling part by the circulating fluid.

After the circulating fluid rinses the milling area, the circulating fluid carries the milling debris. The circulating fluid carrying debris enters the second adapter 10 from the central hollow of the second adapter 10 , and then enters the second cavity 13 formed by the second adapter cavity 11 and the second adapter jacket 12 . Due to the constant pressure, the inner diameter of the second clamping cavity 13 is smaller than the inner diameter of the second conversion joint 10 , that is, the passage of the circulating liquid becomes smaller, which ensures the flow rate of the circulating liquid. Since the second clamping cavity 13 , the seventh clamping cavity 28 , the third clamping cavity 15 , the fifth clamping cavity 22 , the flow hole 24 , the sixth clamping cavity 23 , and the fourth clamping cavity 16 are connected in sequence, the cycle of carrying debris The liquid gradually enters the fourth clamping cavity 16 of the upper conversion cavity part 01 . Since the first clamping cavity 8 in the upper conversion cavity body 01 is connected to the fourth clamping cavity 16 and the first conversion joint 2 respectively, the circulating fluid carrying debris flows out through the central lumen of the first conversion joint 2, and is then circulated by The first conversion joint 2 is connected with the drill pipe and then discharged to the ground to realize the work of reverse circulation milling.

In the horizontal well reverse circulation milling system provided by the embodiment of the present application, the upper conversion cavity part 01 and the lower conversion cavity part 04 are respectively converted inside the first conversion joint 2 and the second conversion joint 10 to realize the circulation of the circulating fluid. This can effectively prevent the occurrence of accidents such as chip sticking, thereby improving milling efficiency and reducing construction risks. The setting of the adjustment part 02 can effectively solve the connection at the inflection point between the horizontal well section and the vertical well section, thereby preventing the circulating fluid with milling debris from being affected by the horizontal well section, so that it can effectively return along the vertical well section ground. The pressure of the pumped circulating fluid drives the hydraulic motor in the hydraulic motor part 03 to operate normally, so as to realize the effective rotation speed and torque at the bottom, and the effective rotational torque acts on the hollow rotating shaft 9, which drives the lower conversion cavity part 04 to rotate, and the sleeve is completed. Milling work, improve milling efficiency.

Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any modifications, uses or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or common knowledge in the technical field not disclosed by the present invention. conventional technical means. The specification and examples are to be regarded as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.

It should be understood that 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 that such entities or operations are the same. any such actual relationship or sequence exists. The present invention is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes may be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims (8)

1. A horizontal well reverse circulation milling system is characterized by comprising an upper conversion cavity part (01), an adjusting part (02), a hydraulic motor part (03) and a lower conversion cavity part (04); two ends of the adjusting part (02) are connected to the upper conversion cavity part (01) and the hydraulic motor part (03) through a first connecting joint (05) and a second connecting joint (06) respectively; the hydraulic motor part (03) and the lower conversion cavity part (04) are connected through a connecting shaft (07);

the upper conversion cavity part (01) comprises a rubber cylinder seat sealing pipe (1), a first conversion joint (2) and a conversion central pipe (3), wherein the end parts of the first conversion joint and the conversion central pipe are connected; a sealing rubber cylinder (5) of a sealing sleeve (4) is arranged outside the rubber cylinder seat sealing pipe (1);

a first conversion cavity (6) is arranged at the end part of the first conversion joint (2), and the first conversion cavity (6) is communicated with the conversion central pipe (3);

a first conversion outer sleeve (7) is arranged outside the end part of the first conversion joint (2), and a first clamping cavity (8) is formed among the first conversion outer sleeve (7), the first conversion joint (2) and the conversion central pipe (3);

the lower conversion cavity part (04) comprises a hollow rotating shaft (9) and a second conversion joint (10) which are connected; a second conversion cavity (11) is arranged at the end part of the second conversion joint (10), and the second conversion cavity (11) is communicated with the hollow rotating shaft (9);

a second conversion outer sleeve (12) is arranged on the outer side of the joint of the hollow rotating shaft (9) and the second conversion joint (10), and a second clamping cavity (13) is formed among the second conversion outer sleeve (12), the hollow rotating shaft (9) and the second conversion joint (10);

the outer side of the hollow rotating shaft (9) is provided with a centering sleeve (14), a third clamping cavity (15) is formed between the centering sleeve (14) and the hollow rotating shaft (9), and the second clamping cavity (13) is communicated with the third clamping cavity (15).

2. The horizontal well reverse circulation milling system according to claim 1, characterized in that a fourth clamping cavity (16) is formed between the rubber cylinder seat sealing pipe (1) and the conversion central pipe (3); the first clamping cavity (8) is communicated with the fourth clamping cavity (16) and the interior of the first adapter (2) respectively.

3. The horizontal well reverse circulation milling system according to claim 1, characterized in that the adjusting part (02) comprises an adjusting sleeve (17), a change-over switch (18) and an extension pipe (19) which are positioned outside the change-over central pipe (3); a switch joint (20) is arranged between the adjusting sleeve (17) and the change-over switch (18);

a connecting outer sleeve (21) is arranged on the outer side of the lengthened pipe (19), and a fifth clamping cavity (22) is formed among the connecting outer sleeve (21), the change-over switch (18), the lengthened pipe (19), the hydraulic motor part (03) and the righting sleeve (14);

a sixth clamping cavity (23) is formed between the change-over switch (18) and the change-over central tube (3); the fifth clamping cavity (22) is communicated with the sixth clamping cavity (23) through a through hole (24).

4. The horizontal well reverse circulation milling system according to claim 3, characterized in that the outside of the extension pipe (19) is provided with a butt joint collar (25).

5. The horizontal well reverse circulation milling system according to claim 3, characterized in that a switch lock ring (26) is provided between the switch joint (20) and the change-over switch (18).

6. The horizontal well reverse circulation milling system according to claim 3, wherein a rotating pipe (27) is arranged outside the hollow rotating shaft (9), and the rotating pipe (27) is in bearing connection with the centralizing sleeve (14); a seventh clamping cavity (28) is formed between the hollow rotating shaft (9) and the rotating pipe (27), and the seventh clamping cavity (28) is respectively communicated with the second clamping cavity (13) and the third clamping cavity (15).

7. The horizontal well reverse circulation milling system according to claim 6, characterized in that a lower pressing cap (29) is arranged between the end of the centralizing sleeve (14) and the rotating pipe (27), and a locking ring (30) is arranged on the lower pressing cap (29).

8. The horizontal well reverse circulation milling system according to claim 1, wherein the hollow rotating shaft (9) and the connecting shaft (07) are connected through a connecting cap (31), and deep groove ball bearings (32) are arranged at the contact positions of the hollow rotating shaft (9), the connecting shaft (07) and the connecting cap (31).

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