CN117231148A - Underground mechanical three-way plugging safety valve for double-layer pipe reverse circulation drilling - Google Patents

Abstract

The invention discloses a downhole mechanical three-way plugging safety valve for double-layer pipe reverse circulation drilling, and relates to the technical field of reverse circulation drilling. The invention utilizes the phenomenon that a large amount of high-speed drilling fluid generated at the bottom of a well when blowout goes back to pass through the abrupt change of a flow passage to generate driving force, a soft rubber core is arranged at the outer layer of a safety valve, an end face sealing structure is arranged at the annular space of a double-layer pipe, a torsion spring and a valve cover are arranged on an inner pipe, meanwhile, a throttling bulge is arranged between a shaft and a drilling column of the double-layer pipe, and a throttling pipe is arranged at the inner pipe of the double-layer pipe and is respectively used as driving force for plugging two passages in the shaft, the annular space of the double-layer pipe and the double-layer pipe, and when the backflow fluid exceeds a design value, three passages in the well can be plugged simultaneously, so that the problem that the current downhole blowout preventer does not have the function of multi-passage plugging is solved; the inner pipe plugging structure is arranged by adopting the throttling effect of high-speed fluid, so that the rock debris migration path is effectively reserved, and the problem that the inner pipe migration channel of the conventional underground blowout preventer is too small is solved.

Description

Underground mechanical three-way plugging safety valve for double-layer pipe reverse circulation drilling

Technical Field

The invention relates to the technical field of reverse circulation drilling, in particular to a double-layer pipe reverse circulation drilling underground mechanical three-way plugging safety valve.

Background

Because the double-layer pipe reverse circulation drilling technology has obvious technical advantages in the oil and gas exploration and development process due to special runner distribution and fluid circulation process, compared with conventional drilling, the double-layer pipe reverse circulation drilling technology has the technical advantages that the drilling speed is higher, the well cleaning efficiency is higher, the leakage of drilling fluid can be effectively reduced in an easy-leakage layer, the reservoir can be effectively protected, the fully-closed circulation of the drilling fluid can be safely drilled in a hydrogen sulfide-containing stratum, and the like, the reverse circulation drilling technology is already applied to multiple fields of coal exploitation, geothermal exploration and development, such as hydrogeological drilling, geology, metallurgy, construction, water conservancy and the like, deep well drilling is required to be carried out in the oil and gas exploration, the geological condition is more complicated, the safety of a wellhead is required to be ensured when accidents such as blowout and well kick occur, and the rapid response and control on dangerous working conditions such as blowout are realized.

The existing problems aiming at the underground safety valve are as follows:

(1) the shutoff of two passageway of double tube is realized at most to current blowout preventer, and this blowout preventer comprises by a set of divided blowout preventer valve, to double tube ring sky passageway respectively, and double tube inner tube passageway needs to open respectively when using, when dangerous operating mode takes place, can not carry out the shutoff to two passageway in the double tube simultaneously.

(2) The blowout preventer of the existing double-layer pipe utilizes the pressure difference between the blowout and normal drilling as driving force, and a partition plate with a larger stress surface is required to be arranged on an inner pipe channel, so that the inner pipe channel is reduced, and the migration of rock debris in the inner pipe is seriously influenced.

(3) The existing blowout preventer for double-layer pipes uses the pressure difference between the blowout time and the normal drilling time as a driving force, and when the bottom hole pressure fluctuates, the blowout preventer is opened and closed, the phenomenon of loose plugging can occur, and the plugging effect is poor.

(4) The existing double-layer pipe blowout preventer adopts a hydraulic driving mode, the reliability of the mode is greatly reduced along with the increase of the drilling depth, and the stability is poor.

(5) The existing blowout preventer at the bottom of the well does not have the condition for carrying out the subsequent well-killing operation after the plugging is completed.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention discloses a double-layer pipe reverse circulation drilling underground mechanical three-way plugging safety valve. The invention aims to solve the technical problem of plugging three channels of underground fluid by double-layer pipe reverse circulation drilling in the prior art; the blowout prevention channel has a plugging function and simultaneously keeps a larger rock debris transporting path; the problem that the current underground blowout preventer does not have a well control function is solved.

The invention utilizes the phenomenon that a large amount of high-speed drilling fluid generated at the bottom of a well when blowout goes back to pass through the abrupt change of a flow passage to generate driving force, a soft rubber core is arranged at the outer layer of a safety valve, an end face sealing structure is arranged at the annular space of a double-layer pipe, a torsion spring and a valve cover are arranged on an inner pipe, meanwhile, a throttling bulge is arranged between a shaft and a drilling column of the double-layer pipe, and a throttling pipe is arranged at the inner pipe of the double-layer pipe and is respectively used as driving force for plugging two passages in the shaft, the annular space of the double-layer pipe and the double-layer pipe, and when the backflow fluid exceeds a design value, three passages in the well can be plugged simultaneously, so that the problem that the current downhole blowout preventer does not have the function of multi-passage plugging is solved; the inner pipe plugging structure is arranged by adopting the throttling effect of high-speed fluid, so that the rock debris migration path is effectively reserved, and the problem that the inner pipe migration channel of the conventional underground blowout preventer is too small is solved; the plugging mechanism is not opened due to bottom hole pressure fluctuation when the throttle pipe reaches a preset position by adopting the C-shaped ring positioning mode, the problem that the current underground blowout preventer is not tight in plugging due to bottom hole pressure fluctuation is solved, meanwhile, after plugging is completed, heavy mud can be injected into the double-layer pipe by adopting the C-shaped ring positioning mode, two channels in the double-layer pipe can be opened, injection well killing of the heavy mud is completed, and the problem that the current underground blowout preventer does not have a well killing function is solved.

In order to achieve the above purpose, the present invention adopts the technical scheme that:

a double-layer pipe reverse circulation drilling underground mechanical three-way plugging safety valve comprises an outer plugging structure, an inner plugging structure and a centralizing structure positioned between the outer plugging structure and the inner plugging structure;

the outer layer plugging structure comprises an outer pipe upper joint, an outer shearing cylinder, an outer connecting pipe and an outer pipe lower joint which are sequentially arranged from top to bottom, wherein a soft rubber core, an extrusion cylinder and a high-rigidity spring are sequentially arranged on the outer wall of the outer connecting pipe from top to bottom, and the extrusion cylinder is fixed with the outer connecting pipe through a shearing pin II; when the underground upward return fluid exceeds a design value, the high-speed fluid drives the extrusion cylinder to move upwards to shear the shear pin II, and the extrusion cylinder pushes the soft rubber core to deform so as to block the annular space between the double-layer pipe and the shaft;

the inner layer plugging structure comprises an inner pipe upper joint, an inner pipe positioning cylinder I, an inner pipe positioning cylinder II, an inner shearing cylinder, an inner connecting pipe and an inner pipe lower joint which are sequentially arranged from top to bottom, wherein a throttle pipe is assembled in the inner pipe upper joint, the inner pipe positioning cylinder I and the inner pipe positioning cylinder II and is limited on the inner pipe positioning cylinder I through a C-shaped ring, an inner pipe plugging mechanism for plugging the inner pipe of the double-layer pipe is arranged in the inner pipe positioning cylinder II, and annular plugging short circuits for plugging the annular space of the double-layer pipe are arranged on the outer walls of the inner pipe upper joint and the inner pipe positioning cylinder I; when the underground upward return fluid exceeds a design value, the high-speed fluid drives the throttle pipe to move upwards to separate from limit, and the throttle pipe drives the annular space plugging short circuit to move upwards to plug the annular space of the double-layer pipe; and simultaneously, after the throttle pipe moves upwards, the inner pipe plugging mechanism acts to plug the inner pipe of the double-layer pipe.

Preferably, the centering structure comprises an upper centering ring and a lower centering ring, wherein the upper centering ring is arranged between the upper outer pipe joint and the upper inner pipe joint, and the lower centering ring is arranged between the lower outer pipe joint and the lower inner pipe joint.

Preferably, the upper joint of the inner tube is connected with the inner tube positioning cylinder I through threads, and the upper centering ring is fixed at the same time.

Preferably, the upper part of the inner tube positioning cylinder I is provided with a positioning shaft shoulder I, the middle part of the inner tube positioning cylinder I is provided with a guide groove, and the lower part of the inner tube positioning cylinder I is provided with a positioning groove I and a positioning groove II.

Preferably, the throttle pipe is provided with a throttle orifice at the upper part, a pin hole at the middle part and a mounting groove at the lower part.

Preferably, the C-shaped ring is arranged in the mounting groove of the throttle pipe, penetrates through the inner pipe positioning cylinder I from the lower part, and is axially and radially fixed under the action of the C-shaped ring, the positioning groove I and the positioning shaft shoulder I.

Preferably, the annular plugging short circuit passes through the guide groove through the connecting pin to be connected with the throttle pipe, and moves along the axial direction of the guide groove along with the throttle pipe.

Preferably, the inner pipe plugging mechanism comprises a valve cover, a valve seat, a torsion spring and a connecting pin; the valve cover is arranged on the valve seat through the connecting pin and the torsion spring, the valve seat is arranged on the inner tube positioning cylinder II through the positioning pin, and the inner tube positioning cylinder II is connected with the inner tube positioning cylinder I through threads.

Preferably, the upper part of the inner connecting pipe penetrates into the inner shearing cylinder and is arranged on the inner shearing cylinder through the shearing pin III; the inner pipe lower joint is fixed with the inner connecting pipe through threads.

Preferably, the upper part of the outer connecting pipe penetrates into the outer shearing cylinder and is connected through the shearing pin I, the soft rubber core penetrates through the outer connecting pipe, and the extrusion cylinder is installed on the outer connecting pipe through the shearing pin II to simultaneously complete the axial fixation of the soft rubber core.

Preferably, the high-stiffness spring is arranged in an annular space between the extrusion cylinder and the outer connecting pipe, the lower joint of the outer pipe is connected with the outer connecting pipe through threads, precompression on the high-stiffness spring is realized at the same time, and the upper joint of the outer pipe is connected with the outer shearing cylinder through threads.

Preferably, the outer wall of the upper part of the outer tube upper joint is provided with a positioning boss I, the inner wall of the middle part is provided with a guiding inclined plane, and the lower part is provided with a connecting thread I.

Preferably, the upper part of the outer shearing cylinder is provided with a connecting thread II, and pin holes I and shaft shoulders I are uniformly distributed on the lower part of the outer shearing cylinder.

Preferably, pin holes II are uniformly distributed in the extrusion cylinder, throttling protrusions are arranged on the outer wall of the upper portion of the extrusion cylinder, and pressurizing grooves are uniformly distributed in the circumferential direction of the extrusion cylinder.

Preferably, the upper part of the outer connecting pipe is provided with a shaft shoulder II and a pin hole III, the middle part is provided with a pin hole IV, and the lower part is provided with threads III.

Preferably, the upper part of the inner tube positioning cylinder II is distributed with positioning pin holes, and the lower part is provided with a boss.

Preferably, the upper part of the annular plugging short joint is provided with a plugging inclined plane, and the lower part is provided with a connecting pin hole.

The invention has the beneficial effects that:

(1) When overflow and blowout occur in the double-layer pipe reverse circulation drilling process, the invention designs the plugging structure of two channels between the annular spaces of the drill pipe shaft and in the double-layer pipe by utilizing the throttling pressure difference effect of the high-speed drilling fluid at the abrupt change position of the flow passage, can automatically complete plugging of underground three channels, and ensures the safety of a wellhead.

(2) The invention uses the throttling pressure difference effect of the high-speed drilling fluid at the abrupt change of the flow passage, adopts the form of valve cover plugging, leaves a larger drift diameter of cuttings transportation in the inner pipe of the double-layer pipe, and does not influence the normal operation of drilling.

(3) The invention adopts the mode of positioning the C-shaped ring and arranging the high-rigidity spring, ensures the plugging effect of the safety valve on three channels after plugging, can not be influenced by bottom hole pressure fluctuation, and ensures reliable plugging performance.

(4) The plugging and unsealing processes of the safety valve are mechanical operation and are not influenced by well depth.

(5) After the plugging is completed, the two channels in the double-layer pipe can be opened again by changing the heavy mud pressure of the annular channel of the double-layer pipe, so that the heavy mud injection well killing is realized.

Drawings

FIG. 1 is a schematic diagram of the safety valve of the present invention in an open state;

FIG. 2 is a schematic view of the safety valve of the present invention in a closed state;

FIG. 3 is a three-dimensional schematic drawing of a quarter section of an upper joint of an outer tube of the present invention;

FIG. 4 is a three-dimensional schematic of an outer shear cylinder of the present invention in quarter section;

FIG. 5 is a three-dimensional schematic of a quarter section of an outer connecting tube according to the present invention;

FIG. 6 is a three-dimensional schematic of a quarter cut-away view of an inner orifice tube of the present invention;

FIG. 7 is a schematic view showing an open state of the inner tube plugging mechanism according to the present invention;

FIG. 8 is a schematic view showing the closing state of the inner tube plugging mechanism according to the present invention;

FIG. 9 is a schematic cross-sectional three-dimensional view of an inner tube positioning barrel I of the present invention;

FIG. 10 is a schematic cross-sectional three-dimensional view of an inner tube positioning barrel II of the present invention;

FIG. 11 is a schematic cross-sectional three-dimensional view of an extrusion barrel of the present invention;

FIG. 12 is a schematic view of a three-dimensional structure of a centering ring of the present invention;

reference numerals:

the device comprises a 1-outer pipe upper joint, a 101-positioning boss I, a 102-guiding inclined plane, a 103-thread I, a 2-centering ring, a 3-annular plugging short joint, a 301-plugging inclined plane, a 302-connecting pin hole, a 4-outer shearing cylinder, a 401-thread II, a 402-shaft shoulder I, a 403-pin hole I, a 5-shearing pin I, a 6-valve seat, a 7-torsion spring, an 8-connecting pin, a 9-valve cover, a 10-shearing pin II, a 11-outer connecting pipe, a 1101-shaft shoulder II, a 1102-pin hole III, a 1103-pin hole IV, a 1104-thread III, a 12-high stiffness spring, a 13-outer pipe lower joint, a 14-inner pipe lower joint, a 15-inner connecting pipe, a 16-shearing pin III, a 17-inner shearing cylinder, an 18-extruding cylinder, a 1801-throttling protrusion 1802-pressurizing groove, a 1803-pin hole II, a 19-inner pipe positioning cylinder II, a 1901-positioning pin hole, a 1902-boss, a 20-soft rubber core, a 21-positioning pin, a 22-C-shaped ring, a 23-positioning pin I, a 23-positioning cylinder 250, a 2-positioning pin I, a 250-2-positioning cylinder I, a 250-positioning pin hole II, a 250-2-positioning pin I, a 250-positioning pin I, a 2-positioning pin hole 250, a 2-positioning pin I, a 250-positioning pin I, a 2-positioning pin II, a 2-positioning pin II, a 250, a positioning pin I, a positioning pin 2 and a positioning pin 2-positioning joint.

Detailed Description

The conception, specific structure, and technical effects produced by the present invention will be clearly and completely described below with reference to the embodiments and the drawings to fully understand the objects, features, and effects of the present invention.

A double-layer pipe reverse circulation drilling downhole mechanical three-way plugging safety valve, as shown in figures 1-12, comprises an outer plugging structure, an inner plugging structure and a centralizing structure positioned between the outer plugging structure and the inner plugging structure;

the outer layer plugging structure comprises an outer pipe upper joint 1, an outer shearing cylinder 4, an outer connecting pipe 11 and an outer pipe lower joint 13 which are sequentially arranged from top to bottom, wherein a soft rubber core 20, an extrusion cylinder 18 and a high-rigidity spring 12 are sequentially arranged on the outer wall of the outer connecting pipe 11 from top to bottom, and the extrusion cylinder 18 is fixed with the outer connecting pipe 11 through a shearing pin II 10; when the underground upward return fluid exceeds a design value, the high-speed fluid drives the extrusion cylinder 18 to move upwards to shear the shear pin II 10, and the extrusion cylinder 18 pushes the soft rubber core 20 to deform and block the annular space (one-channel blocking) between the double-layer pipe and the shaft;

the inner layer plugging structure comprises an inner pipe upper joint 26, an inner pipe positioning cylinder I23, an inner pipe positioning cylinder II 19, an inner shearing cylinder 17, an inner connecting pipe 15 and an inner pipe lower joint 14 which are sequentially arranged from top to bottom, wherein a throttle pipe 25 is assembled in the inner pipe upper joint 26, the inner pipe positioning cylinder I23 and the inner pipe positioning cylinder II 19, the throttle pipe 25 is limited on the inner pipe positioning cylinder I23 through a C-shaped ring 22, an inner pipe plugging mechanism for plugging an inner pipe of the double-layer pipe is arranged in the inner pipe positioning cylinder II 19, and annular space plugging short joints 3 for plugging an annular space of the double-layer pipe are arranged on the outer walls of the inner pipe upper joint 26 and the inner pipe positioning cylinder I23; when the underground upward return fluid exceeds a design value, the high-speed fluid drives the throttle pipe 25 to move upwards to separate from limit, and the throttle pipe 25 drives the annular space plugging short circuit 3 to move upwards to plug the annular space of the double-layer pipe (two-channel plugging); at the same time, after the throttle pipe 25 moves upward, the inner pipe blocking mechanism acts to block the inner pipe of the double-layer pipe (three-way blocking). According to the embodiment, the safety of a wellhead is guaranteed by setting the plugging of the three channels.

As shown in fig. 1, the centering structure includes upper and lower centering rings 2, the upper centering ring 2 being disposed between the outer pipe upper joint 1 and the inner pipe upper joint 26, and the lower centering ring 2 being disposed between the outer pipe lower joint 13 and the inner pipe lower joint 14. The upper centralizing ring 2 is used for centralizing the inner pipe. The inner pipe upper joint 26 is connected with the inner pipe positioning cylinder I23 through threads, and simultaneously, the upper centering ring 2 is fixed.

As shown in fig. 9, a positioning shaft shoulder i 2301 is provided on the upper portion of the inner tube positioning cylinder i 23 for positioning with the inner tube upper joint 26, a guiding groove 2302 is provided in the middle portion, and a positioning groove i 2303 and a positioning groove ii 2304 are provided on the lower portion, for adapting with the C-shaped ring 22.

As shown in fig. 6, the throttle pipe 25 has a throttle 2501 at an upper portion, a pin hole 2502 at a middle portion, and a mounting groove 2503 at a lower portion.

As shown in fig. 1, the C-ring 22 is mounted in a mounting groove 2503 of the throttle pipe 25, penetrates through an inner pipe positioning cylinder i 23 from the lower part, and is axially and radially fixed to the throttle pipe 25 by the C-ring 22, the positioning groove i 2303 and the positioning shoulder i 2301.

As shown in fig. 1, the annulus plugging collar 3 is connected to the choke tube 25 by a connecting pin 24 through a pilot groove 2302 and moves axially along the pilot groove 2302 with the choke tube 25.

As shown in fig. 7 and 8, the inner tube blocking mechanism includes a valve cover 9, a valve seat 6, a torsion spring 7, and a connecting pin 8; the valve cover 9 is arranged on the valve seat 6 through the connecting pin 8 and the torsion spring 7, the valve seat 6 is arranged on the inner tube positioning cylinder II 19 through the positioning pin 21, and the inner tube positioning cylinder II 19 is in threaded connection with the inner tube positioning cylinder I23.

As shown in fig. 1, the upper part of the inner connection pipe 15 penetrates into the inner shear cylinder 17, and is mounted on the inner shear cylinder 17 by a shear pin iii 16; the inner pipe lower joint 14 is screwed to the inner connecting pipe 15.

As shown in fig. 1, the upper part of the outer connecting pipe 11 penetrates into the outer cutting cylinder 4 and is connected through the cutting pin i 5, the soft rubber core 20 penetrates through the outer connecting pipe 11, and the extrusion cylinder 18 is mounted on the outer connecting pipe 11 through the cutting pin ii 10 while axial fixing of the soft rubber core 20 is completed.

As shown in fig. 1, the high rate spring 12 is installed in an annular space between the extrusion cylinder 18 and the outer connection pipe 11, the outer pipe lower joint 13 is connected with the outer connection pipe 11 through threads while precompression of the high rate spring 12 is achieved, and the outer pipe upper joint 1 is connected with the outer shear cylinder 4 through threads.

As shown in FIG. 3, the outer wall of the upper part of the outer pipe upper joint 1 is provided with a positioning boss I101, the inner wall of the middle part is provided with a guiding inclined plane 102, and the lower part is provided with a connecting thread I103.

As shown in fig. 4, the upper part of the outer shearing cylinder 4 is provided with a connecting thread II 401, and the lower part is uniformly provided with a pin hole I403 and a shaft shoulder I402.

As shown in fig. 11, pin holes ii 1803 are uniformly distributed in the extrusion cylinder 18, throttle protrusions 1801 are provided on the outer wall of the upper portion, and pressurizing grooves 1802 are uniformly distributed in the circumferential direction.

As shown in fig. 5, the upper part of the outer connecting pipe 11 is provided with a shaft shoulder ii 1101 and a pin hole iii 1102, the middle part is provided with a pin hole iv 1103, and the lower part is provided with a thread iii 1104.

As shown in fig. 10, the inner tube positioning cylinder ii 19 is provided with positioning pin holes 1901 at the upper part and a boss 1902 at the lower part.

As shown in FIG. 1, the upper part of the annular plugging short circuit 3 is provided with a plugging inclined plane, and the lower part is provided with a connecting pin hole.

In the invention, the high-stiffness spring can generate larger elastic force after precompression. The extrusion force required by the deformation of the soft rubber core is lower than that of the conventional rubber core. The inner layer pipe of the safety valve is connected in an inserting mode, the outer layer pipe is connected with the outer layer pipe in an oil pipe cone threaded mode, and the safety valve can be quickly connected into a standard double-layer drill rod. Shear force required for breaking of shear pin II is lower than that of shear pins I and III.

The working process of the invention is as follows:

in the normal drilling process, the safety valve is in an open state, drilling fluid is pumped from the double-layer pipe annular space, the drilling fluid flows into the upper double-layer pipe annular space, the passing safety valve is arranged in the inner pipe annular space and the outer pipe annular space, the double-layer pipe annular space connected with the lower part of the safety valve is arranged to the bottom of the well, drilling fluid carrying rock debris returns from the inner pipe channel of the double-layer pipe after passing through the bottom drill bit, when the drilling fluid carrying the rock debris passes through the throttle pipe 25, the diameter-changing section gradually becomes smaller due to the through-flow channel, the pressure at the large diameter end of the diameter-changing section is larger than the pressure at the small diameter end of the diameter-changing section, so that pressure drop is formed, upward thrust is generated in the diameter-changing section, the annular space between the double-changing section and the well is in an open state because the C-shaped ring 22 and the positioning groove I2303 exist, the throttle pipe 25 cannot be pushed, the safety valve and the inner pipe plugging mechanism keep in the open state, the drilling fluid carries the rock debris from the inner pipe channel to the ground mud system, meanwhile, in the state in the normal drilling stage, the well drilling fluid is in a low flow speed state, the pressure drop generated in the throttle channel between the well bore 18 and the double-layer pipe, the pressure drop generated in the throttle channel is insufficient to shear pin II 10, in the open state.

When dangerous working conditions such as blowout and the like are met in the drilling process, a great amount of well drilling fluid at the bottom of a well rapidly passes through annular space of a double-layer pipe and a well bore and annular space of the double-layer pipe, the inner pipe channel of the double-layer pipe is rapidly gushed upwards, the well drilling fluid returning upwards from the space between the double-layer pipe and the well bore is larger, when a great amount of well drilling fluid returns upwards in a throttling channel formed between the extrusion 18 cylinder and the well bore at a high speed, because of throttling pressure drop of the fluid, the throttling bulge 1801 and the pressurizing groove 1802 at the upper end of the extrusion 18 can be subjected to upward thrust, when the upper backflow quantity reaches a design threshold value, namely the throttling bulge 1801 and the pressurizing groove 1802 at the upper end of the extrusion 18 can be subjected to upward thrust to reach the design value, the shearing pin II 10 can be sheared under the combined action of the elasticity of the precompaction high-stiffness spring 12 and the thrust, the soft rubber core 20 is extruded by the extrusion 18 to generate deformation to seal the space between the double-layer pipe and the well bore, meanwhile, the drilling fluid returning from the double-layer pipe inner pipe to the throttle pipe 25 of the safety valve forms pressure drop at the throttle port 2501 of the throttle pipe 25, upward thrust is generated at the throttle port 2501, the generated thrust is used for overcoming the resistance of the C-shaped ring 22 in the positioning groove I2303, when the C-shaped ring 22 is deformed and contracted by the thrust into the mounting groove 2503, the throttle pipe 25 moves upwards axially under the action of the thrust while the annular blocking short circuit 3 moves upwards under the driving of the throttle pipe 25 and the throttling thrust generated by the double-layer pipe annular drilling fluid at the annular blocking short circuit, when the blocking inclined plane coincides with the guiding inclined plane 102, the annular blocking short circuit 3 and the throttle pipe 25 move to the axial limit position, the C-shaped ring 22 is positioned in the positioning groove II 2304 at the moment, the double-layer pipe annular is blocked by the annular blocking of the double-layer pipe, the throttle pipe 25 moves upwards, the valve cover 9 rebounds to the valve seat 6 under the action of the torsion spring 7 to complete the double-layer pipe inner pipe, when the bottom hole pressure fluctuates, the two channels of the double-layer pipe cannot be opened due to the positioning function of the C-shaped ring 22 and the action of the torsion spring 7.

And (3) a well killing and safety valve taking-out process: when the underground three-channel is plugged, heavy mud is injected from the ground to the annular channel of the double-layer pipe, when the pressure received by the upper end of the short connection of the plugging annulus is greater than the pressure at the bottom of the well, the short connection of the plugging annulus drives the throttle pipe 25 to move axially downwards, the C-shaped ring 22 is pushed out of the positioning groove II 2304 under the action of thrust, the two channels of the double-layer pipe are opened, the heavy mud is injected from the annular channel of the double-layer pipe, the bottom of the well is replaced by mud and returned to the ground from the inner pipe of the double-layer pipe, well killing is completed, when the well killing is completed, the drilling pressure is increased downwards, the outer shearing cylinder 4 shears the shearing pin I5, the inner shearing cylinder 17 shears the shearing pin III 16, the drill string is lifted, the soft rubber core 20 is restored to be the original shape, the deblocking of the safety valve is completed, the outer shearing cylinder 4 drives the outer connecting pipe 11, the inner shearing cylinder 17 drives the inner connecting pipe 15 to move upwards together to take out the well, and the next use after the shearing pin is replaced.

While the embodiments of the present invention have been described in detail, the present invention is not limited to the embodiments described above, and various equivalent modifications and substitutions can be made by those skilled in the art without departing from the spirit of the present invention, and these are intended to be included in the scope of the present invention as defined in the appended claims.

Claims (17)

1. The underground mechanical three-way plugging safety valve for the double-layer pipe reverse circulation well drilling is characterized by comprising an outer plugging structure, an inner plugging structure and a centralizing structure positioned between the outer plugging structure and the inner plugging structure;

the outer plugging structure comprises an outer pipe upper joint (1), an outer shearing cylinder (4), an outer connecting pipe (11) and an outer pipe lower joint (13) which are sequentially arranged from top to bottom, wherein a soft rubber core (20), an extrusion cylinder (18) and a high-rigidity spring (12) are sequentially arranged on the outer wall of the outer connecting pipe (11) from top to bottom, and the extrusion cylinder (18) is fixed with the outer connecting pipe (11) through a shearing pin II (10); when the underground upward return fluid exceeds a design value, the high-speed fluid drives the extrusion cylinder (18) to move upwards to shear the shear pins II (10), and the extrusion cylinder (18) pushes the soft rubber core (20) to deform and seal the annular space between the double-layer pipe and the shaft;

the inner layer plugging structure comprises an inner pipe upper joint (26), an inner pipe positioning cylinder I (23), an inner pipe positioning cylinder II (19), an inner shearing cylinder (17), an inner connecting pipe (15) and an inner pipe lower joint (14), wherein the inner pipe upper joint (26), the inner pipe positioning cylinder I (23) and the inner pipe positioning cylinder II (19) are sequentially arranged from top to bottom, a throttle pipe (25) is assembled in the throttle pipe (25) and is limited on the inner pipe positioning cylinder I (23) through a C-shaped ring (22), an inner pipe plugging mechanism for plugging an inner pipe of the double-layer pipe is arranged in the inner pipe positioning cylinder II (19), and annular plugging pups (3) for plugging annular spaces of the double-layer pipe are arranged on the outer walls of the inner pipe upper joint (26) and the inner pipe positioning cylinder I (23); when the underground upward return fluid exceeds a design value, the high-speed fluid drives the throttle pipe (25) to move upwards to separate from limit, and the throttle pipe (25) drives the annular space plugging short circuit (3) to move upwards to plug the annular space of the double-layer pipe; and simultaneously, after the throttle pipe (25) moves upwards, the inner pipe plugging mechanism acts to plug the inner pipe of the double-layer pipe.

2. A safety valve according to claim 1, wherein the centering structure comprises an upper and a lower centering ring (2), the upper centering ring (2) being arranged between the outer pipe upper joint (1) and the inner pipe upper joint (26), the lower centering ring (2) being arranged between the outer pipe lower joint (13) and the inner pipe lower joint (14).

3. A safety valve according to claim 2, characterized in that the upper inner tube fitting (26) is screwed to the inner tube positioning cylinder i (23) while the upper centering ring (2) is secured.

4. The safety valve according to claim 1, wherein the upper part of the inner tube positioning cylinder I (23) is provided with a positioning shaft shoulder I (2301), the middle part is provided with a guiding groove (2302), and the lower part is provided with a positioning groove I (2303) and a positioning groove II (2304) up and down.

5. The safety valve according to claim 4, wherein the throttle pipe (25) has a throttle orifice (2501) at an upper portion, a pin hole (2502) at a middle portion, and a mounting groove (2503) at a lower portion.

6. The safety valve according to claim 5, wherein the C-shaped ring (22) is installed in an installation groove (2503) of the throttle pipe (25), and passes through the inner pipe positioning cylinder i (23) from the lower part, and the throttle pipe (25) is axially and radially fixed under the action of the C-shaped ring (22), the positioning groove i (2303) and the positioning shaft shoulder i (2301).

7. Safety valve according to claim 5, characterized in that the annular closure nipple (3) is connected to the throttle tube (25) by means of a connecting pin (24) through the guide groove (2302) and moves axially along the guide groove (2302) with the throttle tube (25).

8. A safety valve according to claim 1, wherein the inner tube blocking mechanism comprises a valve cover (9), a valve seat (6), a torsion spring (7) and a connecting pin (8); the valve cover (9) is arranged on the valve seat (6) through the connecting pin (8) and the torsion spring (7), the valve seat (6) is arranged on the inner tube positioning cylinder II (19) through the positioning pin (21), and the inner tube positioning cylinder II (19) is connected with the inner tube positioning cylinder I (23) through threads.

9. A safety valve according to claim 1, wherein the upper part of the inner connecting tube (15) penetrates into the inner shear cylinder (17) and is mounted on the inner shear cylinder (17) by means of a shear pin iii (16); the inner pipe lower joint (14) is fixed with the inner connecting pipe (15) through threads.

10. A safety valve according to claim 1, wherein the upper part of the outer connecting tube (11) penetrates the outer shear cylinder (4) and is connected by the shear pin i (5), the flexible rubber core (20) penetrates the outer connecting tube (11), and the extrusion cylinder (18) is mounted on the outer connecting tube (11) by the shear pin ii (10) while the axial fixing of the flexible rubber core (20) is completed.

11. A safety valve according to claim 1, characterized in that the high rate spring (12) is mounted in the annular space between the extruder barrel (18) and the outer connecting tube (11), the lower outer tube fitting (13) being screwed to the outer connecting tube (11) while precompression of the high rate spring (12) is achieved, the upper outer tube fitting (1) being screwed to the outer shear barrel (4).

12. The safety valve according to claim 1, wherein the outer wall of the upper part of the outer pipe upper joint (1) is provided with a positioning boss I (101), the inner wall of the middle part is provided with a guiding inclined plane (102), and the lower part is provided with a connecting thread I (103).

13. A safety valve according to claim 1, wherein the upper part of the outer shearing cylinder (4) is provided with connecting threads II (401), and pin holes I (403) and shaft shoulders I (402) are uniformly distributed on the lower part.

14. The safety valve according to claim 1, wherein pin holes ii (1803) are uniformly distributed in the extrusion cylinder (18), throttling protrusions (1801) are arranged on the outer wall of the upper portion, and pressurizing grooves (1802) are uniformly distributed in the circumferential direction.

15. A safety valve according to claim 1, wherein the upper part of the outer connecting pipe (11) is provided with a shaft shoulder ii (1101) and a pin hole iii (1102), the middle part is provided with a pin hole iv (1103), and the lower part is provided with a thread iii (1104).

16. The safety valve according to claim 1, wherein the inner tube positioning cylinder ii (19) is provided with positioning pin holes (1901) at an upper portion and a boss (1902) at a lower portion.

17. Safety valve according to claim 1, characterized in that the upper part of the annular plugging nipple (3) is provided with a plugging bevel and the lower part is provided with a connecting pin hole.