CN216617432U - Incline guide for sidetracking well - Google Patents

Abstract

The utility model discloses an incline guide for sidetracking, which comprises an anchoring mechanism, a throwing pipe and an incline guide body, wherein the lower end of the anchoring mechanism is connected with a lower connector, a throwing release groove communicated with the lower end of a pipe body is arranged in a thread section at the lower end of the throwing pipe, the upper end of the throwing pipe is connected with the upper connector, the lower end of the throwing pipe penetrates through a central hole of the incline guide body and is connected with a connecting head connected in the incline guide body through threads, a cylinder body in the anchoring mechanism below the incline guide body is connected with the connecting head through threads, a well liquid overflow channel is arranged in the connecting head, a limiting piston is fixed in an inner cavity of the connecting head through a throwing shear pin, and the upper piston body of the limiting piston is positioned in the lower inner cavity of the throwing pipe. The tool can be used for the sidetracking construction of coiled tubing and the like which can not rotate a downhole tubular column, and can also be used for the sidetracking construction of conventional downhole tubular columns, and particularly solves the problem that the connecting tubing can not rotate in the releasing procedure of the sidetracking process.

Description

Incline guide for sidetracking well

Technical Field

The utility model relates to a hydraulic seat sealing and releasing sidetracking guider used in a sidetracking process in the petroleum industry, in particular to a sidetracking guider for sidetracking.

Background

The coiled tubing is a tubing made of low carbon alloy steel and has good flexibility, and is also called as flexible tubing, and a roll of coiled tubing is several kilometers long. Coiled tubing sidetrack is the latest developed process, is increasingly applied by the advantages of high operation speed, safety and the like, and can replace conventional tubing to carry out a lot of operations. The coiled tubing operation equipment has the characteristics of operation under pressure and continuous lifting, and has the advantages of small volume, quick operation period, low cost and the like.

In the field of oil field sidetrack drilling operation, when a casing above an oil layer deforms, shrinks or breaks off, so that an oil extraction tool cannot be put into the casing for exploitation, a window is opened at the damaged upper part of the casing, sidetrack drilling is carried out, the casing is drilled to the oil layer and put again, and oil well production is recovered. The function of the slope guider is to provide a slope guiding surface, so that the casing windowing milling cone can open a window on the casing according to a certain slope, an original well hole is avoided, and a well hole is drilled again.

Before sidetracking construction, an inclined guider with an inclined surface structure needs to be sealed in a well seat, so that a window opening tool can be used for drilling the casing along the inclined surface to implement sidetracking operation. The sidetracking construction is generally completed by a drilling machine or a workover rig, if the underground pipe column is formed by connecting conventional oil pipes, the setting of the slope guide can be realized by moving the underground pipe column under the ground or in a hydraulic mode, and then the releasing is realized by rotating the underground pipe column.

At present, the common slope guides used in the production field include the following:

CN200820018980.8 discloses a double-cylinder hydraulic injection deflector for sidetracking window opening, relates to a double-cylinder hydraulic injection deflector for sidetracking window opening in the petroleum industry. The technical scheme is as follows: comprises a seat-sealed slope guiding device which mainly comprises a slope guiding part and a hydraulic part; the inclined guiding part comprises a releasing short section and an inclined building body, the hydraulic part comprises a hydraulic cylinder, a plurality of groups of seat sealing slips, an upper cone, a lower cone and a self-locking mechanism, and the improvement is that the hydraulic cylinder, the plurality of groups of seat sealing slips, the upper cone, the lower cone and the self-locking mechanism are additionally arranged at the other end of the hydraulic part.

The beneficial effect of the above-mentioned patent technique is: the base of the existing single hydraulic cylinder seat seal slope guiding device is additionally provided with a hydraulic cylinder, so that the single hydraulic cylinder seat seal slope guiding device becomes a double-cylinder hydraulic seat seal slope guiding device, the seat seal is firm and reliable, the slope guiding device is guaranteed not to move downwards, and the seat seal slope guiding device solves the problems of the existing slope guiding device.

However, the above-mentioned patented technology can be used only for conventional tubing strings and cannot be used in a sidetracking process where coiled tubing or a downhole string cannot be rotated.

The utility model discloses a salvageable sidetracking integrated deflector disclosed in CN201020232032.1, which relates to a salvageable sidetracking integrated deflector, and is characterized in that the deflector integrated device is formed by oppositely connecting a windowing milling cone and the deflector integrally through a dovetail groove of a connecting sleeve and an inclined plane dovetail groove and then fixing the two through welding; the upper part of the piston cylinder and the wedge base are connected with the slip cylinder through the lower part of the threaded connection, the piston is connected with the upper slip cone through the threaded connection, dovetail grooves milled on the upper slip cone and the lower slip cone respectively are provided with slips with different tooth directions, and a locking block is arranged between the sawtooth locking ring and the central pipe; and the upper and lower packing devices are provided with double rubber cylinders and double packing cushions between the flat pins and the guide heads, and the seat sealing push rod is connected with a hydraulic cylinder and a lower guide head.

The utility model has the advantages that: the directional window opening is facilitated, the multiple tripping procedures are saved, the production cost is low, the working efficiency is improved, the construction period is shortened, and the fishing operation can be carried out.

However, the above-mentioned patented technology can be used only for conventional tubing strings and cannot be used in a sidetracking process where coiled tubing or a downhole string cannot be rotated.

Because coiled tubing used in the coiled tubing sidetracking process can be lowered for several kilometers at one time, the coiled tubing is limited by the structure of the coiled tubing, and the coiled tubing cannot be rotated on the ground in the sidetracking process of the coiled tubing, the conventional manner of releasing the coiled tubing by rotating the coiled tubing cannot be used in the coiled tubing sidetracking process, and a deflector which can realize seat sealing and releasing without moving the coiled tubing needs to be developed, so that the normal implementation of the sidetracking process of the coiled tubing or the tubular string which cannot rotate in the well is ensured.

Disclosure of Invention

The utility model aims to provide a side drilling deflector, which can realize hydraulic seat sealing in a running-in process of a coiled tubing or a side drilling deflector incapable of rotating a downhole tubular column, can smoothly lift a release pipe out under the condition of not rotating the downhole tubular column in a release process of lifting the release pipe in the deflector and retaining a deflection body in the downhole, provides a special deflection tool for side drilling construction of the non-rotatable downhole tubular column, enlarges the application range of the coiled tubing and reduces the production cost.

The technical solution of the utility model is as follows:

the utility model provides a sidetracking well is with leading sloping ware includes anchoring mechanism, loses hand pipe and leads the sloping body, and anchoring mechanism's lower extreme and lower clutch are connected, wherein:

a releasing release groove communicated with the lower end of the pipe body is arranged in the thread section at the lower end of the releasing pipe;

the upper end of the hand throwing pipe is connected with the upper joint, and the lower end of the hand throwing pipe penetrates through the center hole of the inclined guide body and is connected with the connecting head connected in the inclined guide body through threads;

a cylinder in the anchoring mechanism below the inclined guide body is in threaded connection with the coupling head;

a well fluid overflow channel is arranged in the coupling head, the limiting piston is fixed in the inner cavity of the coupling head through the releasing shear pin, and the upper piston body of the limiting piston is positioned in the lower inner cavity of the releasing pipe.

Preferably, a pin hole is formed in the upper body of the coupling head, an anti-rotation pin can be screwed into the pin hole, and the front end of the anti-rotation pin can be inserted into a releasing slot in a thread section at the lower end of the releasing pipe.

Preferably, the number of the releasing slots at the lower part of the releasing pipe is more than three, and the number of the pin holes and the anti-rotation pins in the coupling head is the same as that of the releasing slots in the releasing pipe.

Preferably, the well fluid overflow channel in the coupling head is composed of a radial overflow hole and an axial overflow groove, the axial overflow groove is arranged in the thread section of the coupling head connected with the cylinder body, and the radial overflow hole is communicated with the axial overflow groove.

Preferably, the inner hole of the coupling head is a stepped hole, the hole diameter of the inner hole of the coupling head gradually decreases in steps from top to bottom, the hole diameter of the inner hole of the coupling head is respectively a lost hand pipe assembly table, a limiting piston assembly table, a piston movement limiting table and a coupling head central hole from top to bottom, and a radial overflow hole in the coupling head is formed in the bottom of the limiting piston assembly table.

Preferably, the excircle of the limiting piston is a stepped excircle with non-equal diameter, and the difference between the outer diameter of the upper part and the outer diameter of the middle part of the limiting piston is consistent with the thickness of the lower pipe wall of the hand throwing pipe; the difference between the middle outer diameter and the lower outer diameter of the limiting piston is consistent with the difference between the aperture of the limiting piston assembly table in the coupling head and the aperture of the piston motion limiting table.

Preferably, the height of the piston motion limiting table in the coupling head is consistent with the height of the lower piston body of the limiting piston.

Preferably, the releasing shear pin fixed between the limiting piston and the coupling head is fixed in the limiting piston assembly table of the coupling head and the outer wall of the middle part of the limiting piston.

Preferably, a sealing element is arranged in the outer wall of the limiting piston above the hand-thrown shear pin hole, and a sealing element is also arranged at the lower end of the outer wall of the lower part of the limiting piston.

Preferably, the inclined guide body and the cylinder body which are in threaded connection with the outer wall of the coupling head are welded together at the joint of the outer wall of the coupling head.

The utility model has the following remarkable using effects:

the tool can be used for the sidetracking construction of coiled tubing and the like which can not rotate a downhole tubular column, and can also be used for the sidetracking construction of conventional downhole tubular columns, and particularly solves the problem that the connecting tubing can not rotate in the releasing procedure of the sidetracking process.

The utility model seals the slope guiding device in the casing in a hydraulic mode, and realizes the underground releasing of the slope guiding body in a hydraulic mode, so that the lost hand pipe in the conveyed underground pipe column and the tool is separated from the slope guiding body, and conditions are created for the subsequent casing side drilling windowing construction.

The utility model realizes the transmission of seat seal and hand loss pressure through the limit piston, the connecting head and the anchoring mechanism arranged in the slope guiding device, the well fluid overflow channel arranged in the connecting head provides guarantee for the descending of the limit piston, and the liquid which permeates into the annular space between the connecting head and the limit piston from the slip groove of the anchoring mechanism can be discharged in the descending process of the tool.

The releasing mechanism in the slope guiding device is formed by the releasing pipe, the coupling head and the limiting piston in the tool. The lower part of the releasing pipe is provided with a pipe body part of a releasing groove and is in threaded connection with the coupling head, before the tool does not work, the limiting piston limits the releasing pipe in the inner cavity of the coupling head, and the inner wall of the releasing groove arranged at the lower end of the releasing pipe is supported by the limiting piston and cannot deform. When the pipe is released, the limit piston is pressed downwards to make room for the releasing pipe to separate from the coupling head, the releasing pipe can be conveniently lifted out of the coupling head by lifting the underground pipe column without rotating the underground pipe column, and the inclined guide body in the inclined guide device is released in the sleeve and lifts the upper joint on the upper part and the releasing pipe connected with the upper joint out of the ground. The setting and releasing of the whipstock under the condition of not rotating the underground pipe column are realized, and the implementation of the coiled tubing side drilling process is guaranteed.

The utility model has simple structure and convenient operation, solves the problem that the releasing operation can be realized without rotating the underground pipe column, expands the application range of the coiled tubing and has obvious use effect.

Drawings

The accompanying drawings, which are included to provide a further understanding of the utility model and are incorporated in and constitute a part of this specification, illustrate embodiments of the utility model and together with the description serve to explain the principles of the utility model and not to limit the utility model. In the drawings:

fig. 1 is a schematic view of the overall structure of the present invention.

Fig. 2 is a schematic structural diagram of the releasing mechanism in the utility model.

In the figure: the device comprises an upper joint 1, a releasing pipe 2, an inclined guide body 3, an anti-rotation pin 4, a releasing shear pin 5, a limiting piston 6, a coupling head 7, an upper slip 8, an upper cone 9, a cylinder 10, a lower cone 11, a lower slip 12, a slip screw 13, a sealing ball 14 and a lower joint 15.

Detailed Description

The drawings are for reference and illustration purposes only and are not intended to limit the scope of the present disclosure. The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the utility model, and not restrictive of the full scope of the utility model. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the utility model and do not limit the utility model.

In the description of the present invention, it is to be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships illustrated in the drawings, and are used merely for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be construed as limiting the present invention. Further, in the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

Referring to fig. 1 and 2, a sidetracking whipstock includes an anchoring mechanism, a lost hand tube 2, and a whipstock 3, a lower end of the anchoring mechanism being connected to a lower joint 15, wherein:

a releasing release groove communicated with the lower end of the pipe body is arranged in the thread section at the lower end of the releasing pipe 2;

the upper end of the hand throwing pipe 2 is connected with the upper joint 1, and the lower end of the hand throwing pipe passes through the central hole of the inclined guide body 3 and is connected with a connecting head 7 connected in the inclined guide body 3 through threads;

a cylinder 10 in the anchoring mechanism below the inclined guide body 3 is in threaded connection with the coupling head 7;

a well fluid overflow channel is arranged in the coupling head 7, the limit piston 6 is fixed in the inner cavity of the coupling head 7 through the releasing shear pin 5, and the upper piston body of the limit piston 6 is positioned in the lower inner cavity of the releasing pipe 2.

The anchoring mechanism is provided with an upper cone 9 and a lower cone 11, an upper slip 8 and a lower slip 12 are respectively fixed in the conical surfaces of the upper cone 9 and the lower cone 11 through slip screws 13, the upper slip 8 and the lower slip 12 are respectively installed in slip grooves in a cylinder 10, an inner cavity of the lower part of the lower cone 11 is provided with internal threads to be connected with a setting ball seat, and a sealing ball 14 is installed on the setting ball seat. The inclined guide body 3 is provided with a central hole and an inclined guide surface, and the releasing pipe 2 can penetrate through the central hole to be connected with a coupling head 7 in the inclined guide body 3.

The utility model realizes the transmission of seat sealing and hand pressure loss through a limiting piston 6, a coupling head 7 and an anchoring mechanism arranged in the slope guiding device. The throwing hand tube 2, the coupling head 7 and the limit piston 6 form a releasing mechanism in the incline guider. The well liquid overflow channel arranged in the coupling head 7 provides guarantee for the descending of the limit piston 6, and the well liquid overflow channel in the coupling head 7 can discharge the liquid which permeates into the annular space between the coupling head 7 and the limit piston 6 from the slip groove in the cylinder 10 of the anchoring mechanism in the descending process of the tool.

The utility model is provided with a releasing slot communicated with the lower end of the pipe body in the thread section of the lower end of a releasing pipe 2, and the lower end of the releasing pipe 2 passes through the central hole of an inclined guide body 3 and is connected with a coupling head 7 arranged in the inclined guide body 3 through threads; the well fluid overflow channel is arranged in the coupling head 7, the limiting piston 6 is connected with the coupling head 7 through the releasing shear pin 5, and the lower threaded pipe body provided with the releasing groove in the releasing pipe 2 is clamped between the limiting piston 6 and the coupling head 7, so that the stability of connection between the releasing pipe 2 and the inclined guide body 3 is guaranteed.

The tool is used as an auxiliary tool for casing windowing to carry out side drilling well bore construction, and before side drilling of a well bore is carried out in a casing, the tool needs to be released at a preset casing position, and the tool needs to be seated first and then released.

When the tool is connected to the lower end of a downhole tubular column through the upper connector 1, the whipstock is lowered into a well to a preset position, the ground is pressed into the well through the downhole tubular column, under the action of hydraulic pressure, the upper cone 9 and the lower cone 11 cut off the slip screw 13 and then move upwards and downwards respectively, the upper slip 8 and the lower slip 12 are pushed to expand outwards and are clamped on a sleeve, and the setting of the tool is completed.

After the tool is sealed, the tool continues to be pressed into the underground pipe column in the well, and when the pressure rises to a set value, the releasing shear pin 5 in the limiting piston 6 moves downwards after being sheared by axial thrust, so that an operation space is made for smoothly pulling out the releasing pipe 2. At the moment, the downhole pipe string is lifted up, so that the pipe body part of the lower part of the lost hand pipe 2 provided with the releasing slot is deformed and is separated from the threaded connection relation with the coupling head 7. The whipstock can be conveniently released in the casing by lifting the downhole string, the upper joint 1 at the upper part and the releasing pipe 2 connected with the upper joint are lifted out of the ground, the setting and releasing of the whipstock under the condition of not rotating the downhole string are realized, and the implementation of the side drilling process that the coiled tubing and the downhole string cannot rotate is guaranteed.

On the basis of the above-described embodiments, the present invention also has the following embodiments:

a preferred embodiment: a pin hole is formed in the upper body of the coupling head 7, an anti-rotation pin 4 can be screwed in the pin hole, and the front end of the anti-rotation pin 4 can be inserted into a releasing slot in the thread section at the lower end of the lost hand pipe 2. The stability of being connected between hand losing pipe 2 and coupling head 7 can further be strengthened, the two takes place not hard up the separation in the process of going into the well. In addition, the releasing slot at the lower part of the lost hand pipe 2 is a slot body communicated with the lower end, so that the releasing process of the lifting downhole pipe column does not hinder the lifting of the lost hand pipe 2.

A preferred embodiment: the releasing grooves at the lower part of the releasing pipe 2 are more than three, and the number of the pin holes in the coupling head 7 and the number of the anti-rotation pins 4 are the same as that of the releasing grooves in the releasing pipe 2.

A preferred embodiment: the well fluid overflow channel in the coupling head 7 consists of a radial overflow hole and an axial overflow groove, the axial overflow groove is arranged in the thread section of the coupling head 7 connected with the cylinder 10, and the radial overflow hole is communicated with the axial overflow groove.

A preferred embodiment: the inner hole of the coupling head 7 is a stepped hole, the aperture of the inner hole of the coupling head 7 is gradually stepped from top to bottom, and is respectively a lost-hand tube assembly platform, a limiting piston assembly platform, a piston motion limiting platform and a coupling head central hole from top to bottom, and a radial overflow hole in the coupling head 7 is formed in the bottom of the limiting piston assembly platform.

A preferred embodiment: the excircle of the limiting piston 6 is a non-constant-diameter stepped excircle, and the difference between the outer diameter of the upper part and the outer diameter of the middle part of the limiting piston 6 conforms to the thickness of the lower pipe wall of the hand throwing pipe 2; the difference between the middle outer diameter and the lower outer diameter of the limit piston 6 is consistent with the difference between the bore diameter of the limit piston assembly platform in the coupling head 7 and the bore diameter of the piston motion limit platform.

A preferred embodiment: the height of the piston motion limiting table in the coupling head 7 is consistent with the height of the lower piston body of the limiting piston 6.

A preferred embodiment: and the releasing shear pin 5 fixed between the limiting piston 6 and the coupling head 7 is fixed in a limiting piston assembly table of the outer wall of the middle part of the limiting piston 6 and the coupling head 7.

A preferred embodiment: and a sealing element is arranged in the outer wall above the hand-throwing shear pin hole in the limiting piston 6, and a sealing element is also arranged at the lower end of the outer wall at the lower part of the limiting piston 6. The two sealing elements can form sealing between the limiting piston 6 and the coupling head 7, the diameters of the two sealing elements in the limiting piston 6 are different, and the two sealing elements can generate downward thrust on the limiting piston 6 under the action of internal pressure and area difference.

A preferred embodiment: the inclined guide body 3 and the cylinder body 10 which are in threaded connection with the outer wall of the coupling head 7 are welded together at the joint of the outer wall of the coupling head 7. The utility model welds the inclined guide body 3, the cylinder body 10 and the coupling head 7 into a whole, and improves the connection strength of the three.

The tool is used as an auxiliary tool for casing windowing to carry out side drilling borehole construction, and the specific working process is as follows:

1. the lower end of the underground pipe column is connected with the upper joint 1, and then the inclined guider is put into a preset position in the well.

2. And (3) pressing from the inside of the oil pipe, wherein under the action of pressure, the upper cone 9 and the lower cone 11 cut off the slip screw 13 and then move upwards and downwards respectively to push the upper slip 8 and the lower slip 12 to expand outwards and clamp the slips on the casing pipe to complete the setting of the tool.

3. After the tool is sealed, the releasing pipe 2 in the tool is lifted out of the ground, the inclined guide body 3 and other parts are retained in the casing, then the casing windowing tool is put into the casing by the operating pipe column, and a well hole is drilled along the inclined guide surface of the inclined guide body 3 in the tool; when releasing the operation, firstly, hydraulic pressure is applied to the oil pipe.

4. Because the sealing diameters of two sealing elements in the sealing matching surfaces of the limiting piston 6 and the coupling head 7 are different, the limiting piston 6 is pushed downwards under the action of the difference between the internal pressure and the area. When the pressure in the underground pipe column rises to the shearing value of the releasing shear pin 5, the axial thrust of the limiting piston 6 shears the releasing shear pin 5 and then moves downwards, the limiting piston 6 moves downwards from the inner cavity of the releasing release groove arranged at the lower part of the releasing pipe 2, and the well fluid remained between the limiting piston 6 and the coupling head 7 is discharged through the well fluid overflow channel in the downward moving process of the limiting piston 6. The moving down of the limit piston 6 changes the original matching structure, under the action of the releasing slot at the lower part of the releasing pipe 2, the releasing pipe 2 is in a loose connection state with the thread connection relation of the coupling head 7, and the releasing slot at the lower part of the releasing pipe 2 is a groove body structure communicated with the lower end of the releasing pipe, so that the underground pipe column is lifted up, the pipe body inside shrinkage deformation of the releasing slot at the lower part of the releasing pipe 2 can be caused, the pipe body is smoothly released and separated from the incline guide device, and the releasing operation of the tool is realized under the condition of the pipe column under the non-rotation well.

The embodiments described above are merely exemplary embodiments, but the present invention is not limited to these embodiments, and those skilled in the art can make modifications without departing from the spirit and teaching of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof. Any modification, equivalent replacement, improvement and the like made within the spirit and inventive concept of the present invention should be included in the protection scope of the present invention. The scope of protection is therefore not limited to the description above.

Claims (10)

1. The utility model provides a sidetracking well is with leading sloping ware, includes anchoring mechanism, loses hand pipe and leads the sloping, and anchoring mechanism's lower extreme and lower clutch are connected characterized by:

a releasing release groove communicated with the lower end of the pipe body is arranged in the thread section at the lower end of the releasing pipe;

the upper end of the hand throwing pipe is connected with the upper joint, and the lower end of the hand throwing pipe penetrates through the center hole of the inclined guide body and is connected with the connecting head connected in the inclined guide body through threads;

a cylinder in the anchoring mechanism below the inclined guide body is in threaded connection with the coupling head;

a well fluid overflow channel is arranged in the coupling head, the limiting piston is fixed in the inner cavity of the coupling head through the releasing shear pin, and the upper piston body of the limiting piston is positioned in the lower inner cavity of the releasing pipe.

2. The lateral drilling slant guide of claim 1, wherein a pin hole is formed in the upper body of the coupling head, an anti-rotation pin is screwed into the pin hole, and a front end of the anti-rotation pin is inserted into a release groove in a threaded section of a lower end of the release pipe.

3. The lateral drilling slant guide of claim 2, wherein three or more releasing slots are provided in a lower portion of the lost motion pipe, and the number of the pin holes and the rotation preventing pins in the coupling head is the same as the number of the releasing slots in the lost motion pipe.

4. The angle guide of claim 1, 2 or 3, wherein the well fluid overflow channel of the coupling head comprises a radial overflow hole and an axial overflow groove, the axial overflow groove is arranged in the screw thread section of the coupling head connected with the cylinder body, and the radial overflow hole is communicated with the axial overflow groove.

5. The angle guide for sidetracking according to claim 4, wherein the inner bore of the coupling head is a stepped bore, the bore diameter of the inner bore of the coupling head decreases stepwise from top to bottom and is respectively a lost motion tube assembly table, a limit piston assembly table, a piston movement limit table and a central bore of the coupling head from top to bottom, and a radial overflow hole in the coupling head is formed at the bottom of the limit piston assembly table.

6. The lateral drilling slant guide of claim 5, wherein the outer circle of the limit piston is a stepped outer circle with non-equal diameter, and the difference between the upper outer diameter and the middle outer diameter of the limit piston is in accordance with the thickness of the lower pipe wall of the lost-hand pipe; the difference between the middle outer diameter and the lower outer diameter of the limiting piston is consistent with the difference between the aperture of the limiting piston assembly table in the coupling head and the aperture of the piston motion limiting table.

7. The sidetracking whipstock as claimed in claim 5 wherein the height of the piston motion limiting table in said coupling corresponds to the height of the lower piston body of the limiting piston.

8. The angle guide for sidetracking according to claim 6, wherein the releasing shear pin fixed between the limit piston and the coupling head is fixed in the limit piston assembly table of the coupling head and the middle outer wall of the limit piston.

9. The sidetracking drill slope guide according to claim 8, wherein a sealing member is provided in the upper outer wall of the hand drop shear hole in said limit piston and a sealing member is also provided at the lower end of the lower outer wall of the limit piston.

10. The sidetracking whipstock of claim 1 wherein the whipstock and the barrel threadingly engaged to the outer wall of the coupling are welded together at the junction of the outer wall of the coupling.

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