A jam-preventing capsule for large-size cavern formation drilling operations

Abstract

The application provides a jam-preventing capsule for large-size cave stratum drilling operation, which comprises a circulating unit, a first circulating hole and a liquid injection hole arranged on the circulating unit, a capsule unit connected to the lower end of the circulating unit, a capsule arranged on the capsule unit, the capsule being capable of being filled with cement slurry, and a pressure meeting unit arranged on the upper end of the circulating unit, the pressure meeting unit being provided with a second circulating hole; wherein the first circulating hole of the circulating unit is open and the liquid injection hole is closed at the beginning, the first circulating hole is closed and the liquid injection hole is open after a switch plug is put in, and then the cement slurry poured in enters the capsule unit through the liquid injection hole; after a pressure meeting plug is put in, the second circulating hole is open, circulation is established, the capsule unit is separated from the circulating unit by means of upward lifting or back-off, and the releasing is realized.

Description

Technical Field

[0001] This invention relates to an anti-jamming capsule for drilling operations in large-sized karst formations, belonging to the field of oil and gas. Background Technology

[0002] The southeastern part of the Sichuan Basin is characterized by karst topography. During shale gas exploration and development, drilling often encounters formation fissures, underground flowing rivers, and large karst caves. This can easily lead to severe leakage or leakage connected to surface waterways. The caves are multi-layered, and falling rocks and debris, as well as rock fragments carried by flowing water, can enter the annulus of the wellbore during drilling, causing high friction and torque. This severely affects the normal progress of drilling operations and can also lead to other types of downhole problems, even causing well collapse, stuck drill bit, drill string breakage, or disconnection. This significantly increases the drilling cycle in shallow formations, resulting in high drilling rig day costs and drilling costs.

[0003] Currently, the common solutions are to plug the leaks by inserting sealing materials or backfilling the wellbore with cement. However, since karst caves are often connected to underground rivers, neither method is very effective and cannot fundamentally solve the problem of stuck drill bits caused by leakage from large karst caves. This problem severely restricts the exploration and development of shallow karst shale gas wells in the Sichuan Basin. Summary of the Invention

[0004] To address the aforementioned technical problems in existing technologies, this invention proposes an anti-sticking capsule for drilling operations in large-sized karst formations. An "artificial island" is constructed in the wellbore of a large-sized karst cave, which is a certain height above the surface of the cave. This guides the flow rocks to flow away along the perimeter of the artificial island, while preventing and reducing the entry of falling rocks, flow rocks, or fragments from the top and surrounding areas of the cave into the wellbore. This avoids derivative accidents such as stuck drill bits and drill string breakage during drilling.

[0005] This invention proposes an anti-jamming capsule for drilling operations in large-sized karst cave formations, comprising:

[0006] A circulation unit, wherein the circulation unit is provided with a first circulation hole and a liquid injection hole;

[0007] A capsule unit connected to the lower end of the circulation unit, the capsule unit having a capsule capable of being filled with cement slurry; and

[0008] A pressing unit is provided at the upper end of the circulation unit, and the pressing unit is provided with a second circulation hole;

[0009] Wherein, the first circulation hole of the circulation unit is opened and the injection hole is closed at the initial time, the first circulation hole is closed and the injection hole is opened after the switch plug is put in, and then the grouting cement slurry is poured into the capsule unit through the injection hole; after the pressure plug is put in, the second circulation hole is opened to establish circulation, the capsule unit is separated from the circulation unit by lifting or reverse tripping to complete the releasing.

[0010] The further improvement of the present application is that the releasing unit is arranged between the capsule unit and the circulation unit, the capsule unit is separated from the circulation unit by lifting the drilling tool under the self-weight of the capsule unit to realize releasing, or the capsule unit is separated from the circulation unit by rotating the drilling tool to realize releasing.

[0011] The further improvement of the present application is that the circulation unit comprises a circulation sub, the first circulation hole is arranged on the circulation sub along the radial direction, the inner part of the circulation sub is provided with a sliding sleeve, the bottom of the sliding sleeve is provided with the injection hole, and the upper part of the sliding sleeve is provided with a communication hole.

[0012] In the initial state, the sliding sleeve is in the first position, the first circulation hole is communicated with the communication hole, and the injection hole is blocked by the circulation sub and in the closed state; when the switch plug is connected with the sliding sleeve and pushes the sliding sleeve to slide to the second position, the circulation hole is staggered with the communication hole, and the injection hole is opened.

[0013] The further improvement of the present application is that in the initial state, the sliding sleeve is connected with the circulation sub through the first shear pin in the first position, when the switch plug is connected with the sliding sleeve, the pressure above the switch plug is relieved, the pin is sheared under the action of the pressure, and the sliding sleeve is moved to the second position.

[0014] The further improvement of the present application is that the inner wall of the circulation sub is provided with an inner step, the outer wall of the sliding sleeve is provided with an outer step, when the inner step moves to the upper of the outer step, the sliding sleeve is fixed in the second position.

[0015] The further improvement of the present application is that the switch plug comprises a mandrel, the outer wall of the rear end of the mandrel is provided with a plurality of rubber bowls, the front end of the mandrel is provided with a guide head, and the guide head is connected with the mandrel through the second shear pin.

[0016] The further improvement of the present application is that the bottom of the sliding sleeve is provided with a receiving cavity, and the guide head is separated from the mandrel and moved into the receiving cavity.

[0017] The further improvement of the present application is that the capsule unit comprises a sleeve, the upper end of the sleeve is connected with a support fixing mechanism through a third shear pin, and the lower end of the support fixing mechanism is provided with a connection with the capsule;

[0018] When the drilling tool is pulled up, the third shear pin is sheared, so that the sleeve is separated from the support fixing mechanism and the capsule.

[0019] The further improvement of the present application is that the lower end of the sleeve is provided with a circular guide head, and the circular guide head is connected with the sleeve through a fourth shear pin.

[0020] The further improvement of the present application is that the support fixing mechanism comprises a shear sleeve connected with the third shear pin, the lower end of the shear sleeve is provided with a connecting sleeve, the lower end of the connecting sleeve is provided with an arc-shaped fixing sleeve, and the lower end of the fixing sleeve is provided with a support sleeve.

[0021] The support sleeve comprises an upper support sleeve and a lower support sleeve, and the capsule is sealingly connected between the upper support sleeve and the lower support sleeve.

[0022] The further improvement of the present application is that the releasing unit comprises a back-off joint connected below the circulating unit, and a back-off nut connected with the capsule unit.

[0023] The back-off joint is connected with the back-off nut through threads, the back-off joint is further connected with the sleeve through back-off threads, and the back-off nut is connected with the sleeve and the support fixing mechanism through the third shear pin.

[0024] The further improvement of the present application is that the bumping and pressing unit comprises an upper joint, the side wall of the upper joint is provided with the second circulating hole in the radial direction, the inside of the upper joint is provided with a bumping and pressing seat, the bumping and pressing seat is connected with the upper joint through a fifth shear pin in an initial state and blocks the second circulating hole, the fifth shear pin is sheared when the bumping and pressing plug is connected with the bumping and pressing seat and the pressure is built up, the bumping and pressing seat moves and opens the second circulating hole.

[0025] The further improvement of the present application is that the bumping and pressing plug comprises an integrated mandrel, and the rear end of the integrated mandrel is provided with a plurality of rubber bowls.

[0026] Compared with the prior art, the present application has the following advantages:

[0027] The anti-sticking capsule for large-size karst cave drilling operation of the present application establishes an "artificial island" with a certain height above the ground of the large-size karst cave, guides the flowstone to flow along the artificial island, and prevents and reduces the falling stones, flowstones or broken zone falling blocks around the top of the karst cave from entering the wellbore, thereby avoiding the occurrence of accidents such as sticking of the drilling wellbore, breaking off of the drilling tool and the like. Attached Figure Description

[0028] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, in which:

[0029] Figure 1 The diagram shown is a schematic representation of an anti-jamming capsule for drilling operations in large-sized karst formations according to an embodiment of the present invention.

[0030] Figure 2 The diagram shown is a schematic representation of the structure of a loop unit according to an embodiment of the present invention;

[0031] Figure 3 The diagram shown is a structural schematic of the drop-off unit and capsule unit according to an embodiment of the present invention;

[0032] Figure 4 The diagram shown is a structural schematic of a pressing unit according to an embodiment of the present invention;

[0033] Figure 5 The diagram shown is a schematic representation of the structure of a switch plug according to an embodiment of the present invention;

[0034] Figure 6 The diagram shown is a structural schematic of a pressure plug according to an embodiment of the present invention;

[0035] The meanings of the reference numerals in the attached figures are as follows:

[0036] 1. Pressing unit, 2. Circulation unit, 3. Release unit, 4. Capsule unit, 5. Switch plug, 6. Pressing plug, 11. Upper connector, 12. Pressing seat, 13. Fifth shear pin, 14. Second circulation hole, 21. Circulation short section, 22. Sliding sleeve, 23. First circulation hole, 24. Injection hole, 25. Outer step, 26. Inner step, 27. Connecting hole, 28. Receiving cavity, 29. First shear pin, 31. Backed connector, 32. Backed nut, 33. Third shear pin, 41. Shearing sleeve, 42. Connecting sleeve, 43. Fixing sleeve, 44. Upper support sleeve, 45. Lower support sleeve, 46. Capsule, 47. Sleeve, 48. Fourth shear pin, 49. Circular guide head, 51. Rubber cup, 52. Mandrel, 53. Second shear pin, 54. Guide head, 61. Rubber cup, 62. Integrated mandrel, 63. Sealing ring. Detailed Implementation

[0037] To make the technical solutions and advantages of the present invention clearer, exemplary embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not an exhaustive list of all embodiments. Furthermore, without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0038] Figure 1 A stuck-preventing capsule for large-size cave formation drilling operation according to the present application is schematically shown, which comprises a circulating unit 2, the circulating unit 2 is provided with a first circulating hole 23 and a liquid injection hole 24, the first circulating hole 23 is used for circulating operation, and the liquid injection hole 24 is used for injecting liquid such as cement slurry, in the circulating operation, the first circulating hole 23 is opened, and the liquid injection hole 24 is closed, in the injection of cement slurry, the first circulating hole 23 is closed, and the liquid injection hole 24 is opened. A capsule unit 4 is arranged at the lower end of the circulating unit 2, the capsule unit 4 is provided with a capsule 46, the capsule 46 can be filled with cement slurry and can be expanded under the action of the cement slurry. The upper end of the circulating unit 2 is provided with a bumping unit 1, the bumping unit 1 is provided with a second circulating hole 14 for re-establishing circulation. The embodiment also comprises a switch plug 5 and a bumping plug 6, which are put into the wellhead for changing the state of the circulating unit 2 and the bumping unit 1 in the well.

[0039] In the stuck-preventing capsule for large-size cave formation drilling operation according to the embodiment, the first circulating hole 23 of the circulating unit 2 is opened and the liquid injection hole 24 is closed at the beginning, after the switch plug 5 is put in, the first circulating hole 23 is closed and the liquid injection hole 24 is opened, then the cement slurry poured in enters the capsule unit 4 through the liquid injection hole 24, then the capsule unit 4 is separated from the circulating unit 2 by means of lifting or back-off, and the releasing is completed. The capsule 46 falls to the predetermined position, and after the cement slurry is solidified, an "artificial island" is established to compact the falling rocks, and the falling rocks are placed into the wellbore again. After the cement slurry is poured in, the bumping plug 6 is put in, the bumping plug 6 acts on the bumping unit 1, the second circulating hole 14 is opened, and the circulation is re-established.

[0040] In one embodiment, as shown in Figure 1 A releasing unit 3 is arranged between the capsule unit 4 and the circulating unit 2, the releasing unit 3 separates the capsule unit 4 from the circulating unit 2 under a certain pressure to realize releasing. Alternatively, the capsule unit 4 is separated from the circulating unit 2 by rotating to realize releasing.

[0041] Under normal circumstances, the capsule unit 4 is separated from the circulating unit 2 by lifting the drilling tool under the action of the self-weight of the capsule unit 4 to complete releasing; when the pressure releasing fails, the capsule unit 4 can be separated from the circulating unit 2 by rotating. Through the two releasing modes, it is ensured that the releasing can be normally completed under abnormal circumstances.

[0042] In one embodiment, as shown in Figure 2 The circulating unit 2 comprises a circulating short section 21, the first circulating hole 23 is arranged radially on the circulating short section 21, the circulating short section 21 is provided with a sliding sleeve 22, the bottom of the sliding sleeve 22 is arranged radially, the liquid injection hole 24 is arranged on the bottom of the sliding sleeve 22, and the upper part of the sliding sleeve 22 is provided with a communication hole 27.

[0043] In the initial state, the sliding sleeve 22 is in the first position, the first circulation hole 23 is connected to the connecting hole 27, and the injection hole 24 is blocked by the circulation short section 21 and is in a closed state; when the switch plug 5 is connected to the sliding sleeve 22 and pushes the sliding sleeve 22 to slide to the second position, the circulation hole and the connecting hole 27 are misaligned, and at this time the bottom of the sliding sleeve 22 slides out of the circulation short section 21, so that the injection hole 24 is opened.

[0044] In a preferred embodiment, in the initial state, the sliding sleeve 22 is connected to the circulating short section 21 in the first position through the first shear pin 29. When the switch plug 5 is engaged, the switch plug 5 is inserted into the inside of the sliding sleeve 22, blocking the central hole of the sliding sleeve 22 and connecting with the sliding sleeve 22. Pressure is applied above it, and under the action of pressure, the pin is sheared, causing the sliding sleeve 22 to move to the second position.

[0045] In one embodiment, the inner wall of the circulating subsection 21 is provided with an annular boss, the upper end of which forms an inner step 26. The lower part of the outer wall of the sliding sleeve 22 is provided with an annular groove, the upper end of which forms an outer step 25. In the initial state, the sliding sleeve 22 is in the first position, and there is a certain distance between the outer step 25 and the inner step 26. The injection hole 24 is blocked inside the boss. When the switch plug 5 is connected to the sliding sleeve 22 and pressurized, the sliding sleeve 22 slides downward under the pressure. When it moves to the point where the outer step 25 contacts the inner step 26, the sliding sleeve 22 will not continue to move downward due to the obstruction of the outer step 25. At this time, the sliding sleeve 22 is fixed in the second position. At the same time, the lower end of the sliding sleeve 22 extends downward, and the injection hole 24 moves to the bottom of the boss, thereby opening.

[0046] In one embodiment, such as Figure 5 As shown, the switch plug 5 includes a spindle 52, which has a tubular structure. Several rubber cups are provided on the outer wall of the rear end of the spindle 52. The rubber cups have a conical, semi-circular, or arcuate shape, with a larger radius at the rear end and a smaller radius at the front end to facilitate forward movement. A guide head 54 is provided at the front end of the spindle 52. The front end of the guide head 54 has a conical or arcuate shape to reduce resistance to forward movement. The guide head 54 is connected to the spindle 52 via a second shear pin 53.

[0047] In one embodiment, the bottom of the sliding sleeve 22 is provided with a receiving cavity 28, and the guide head 54 moves into the receiving cavity 28 after separating from the spindle 52.

[0048] In the use of the anti-sticking capsule for large size cave formation drilling operation according to the present embodiment, in the initial state, the sliding sleeve 22 is in the first position, the first circulation hole 23 is open for circulation operation, and the injection hole 24 is in the closed state. After the switch plug 5 is put in, the switch plug 5 moves to and is fixed on the sliding sleeve 22. Continue to pressurize, the first shear pin 29 is broken, the sliding sleeve 22 moves from the first position to the second position, the first circulation hole 23 is closed, and the injection hole 24 is open. Continue to pressurize, when the pressure reaches a certain value, the second shear pin 53 is broken, the guide head 54 is separated from the mandrel 52, the guide head 54 moves downward under the action of pressure and falls into the receiving cavity 28, at this time, the central hole of the mandrel 52 is open to the injection hole 24, and the cement slurry can be injected into the capsule unit 4.

[0049] Preferably, a plurality of sealing grooves are arranged on the outer wall of the sliding sleeve 22, and sealing rings are arranged in the sealing grooves. Two groups of sealing rings are arranged on both sides of the injection hole 24, and two groups of sealing rings are also arranged on both sides of the first circulation hole 23 in the second position.

[0050] In one embodiment, as shown in Figure 3 The capsule unit 4 includes a sleeve 47, which is a cylindrical structure. The upper end of the inside of the sleeve 47 is provided with a support fixing mechanism for supporting the capsule 46. The sleeve 47 is connected with the support fixing mechanism through a third shear pin 33. The lower end of the support fixing mechanism is provided with the capsule 46.

[0051] After the cement slurry is injected, the cement slurry enters the capsule 46, and the capsule 46 expands. After the injection is completed, the third shear pin 33 is broken by lifting the drilling tool, so that the sleeve 47 is separated from the support fixing mechanism and the capsule 46, and the releasing hand is completed. The capsule 46 falls into the predetermined area.

[0052] In one embodiment, the lower end of the sleeve 47 is provided with a circular guide head 49, which is connected with the sleeve 47 through a fourth shear pin 48 and is sealed by a sealing ring. At the beginning, the circular guide head 49 can reduce the resistance when entering the well and can protect the capsule 46. After the capsule 46 expands, the fourth shear pin 48 is broken under the action of a certain pressure, so that the circular guide head 49 is separated from the sleeve 47, and after the releasing hand is completed, the capsule 46 can fall down smoothly.

[0053] In one embodiment, the support fixing mechanism comprises a shearing sleeve 41 connected to the third shear pin 33, which is annular in structure, and the lower end of the shearing sleeve 41 is provided with a connecting sleeve 42. The connecting sleeve 42 is tubular in structure, the upper end is connected to the shearing sleeve 41, and the lower end extends into the inside of the casing 47. The lower end of the connecting sleeve 42 is provided with an arc-shaped fixing sleeve 43, and the lower end of the fixing sleeve 43 is provided with a support sleeve that supports the capsule 46 in an expanded state, facilitating the entry of cement slurry. The support sleeve comprises an upper support sleeve 44 and a lower support sleeve 45, and the capsule 46 is sealingly connected between the upper support sleeve 44 and the lower support sleeve 45.

[0054] In one embodiment, as shown in Figure 3 The release unit 3 comprises a back-off joint 31 connected below the circulating unit 2, and a back-off nut 32 connected to the capsule unit 4. The back-off joint 31 is connected to the back-off nut 32 by threads, the back-off joint 31 is also connected to the casing 47 by back-off threads, and the back-off nut 32 is connected to the casing 47 and the support fixing mechanism through the third shear pin 33.

[0055] After the cement slurry injection operation is completed and circulation is re-established, the drilling tool is pulled up, the third shear pin 33 in the release unit 3 is sheared off, and the capsule 46, the shearing sleeve 41, the connecting sleeve 42, the fixing sleeve 43, the upper support sleeve 44, and the lower support sleeve 45 in the capsule unit 4 fall to the bottom of the well together. When the third shear pin 33 in the release unit 3 fails to release and shear off, it can be turned clockwise, the back-off nut 32 is disconnected from the back-off joint 31, and the capsule 46, the shearing sleeve 41, the connecting sleeve 42, the fixing sleeve 43, the upper support sleeve 44, the lower support sleeve 45, the shear pin, and the back-off nut 32 fall to the bottom of the well together.

[0056] In one embodiment, as shown in Figure 4 The pressure bumping unit 1 comprises an upper joint 11, the side wall of the upper joint 11 is provided with the second circulating hole 14 in the radial direction; the inside of the upper joint 11 is provided with a pressure bumping seat 12, which is connected to the upper joint 11 by a fifth shear pin 13 in the initial state and blocks the second circulating hole 14, and is provided with sealing rings on both sides. When the pressure bumping plug 6 is connected to the pressure bumping seat 12 and pressure is built up, the fifth shear pin 13 is sheared off, the pressure bumping seat 12 moves and opens the second circulating hole 14.

[0057] In one embodiment, as shown in Figure 6 The pressure bumping plug 6 comprises an integrated mandrel 62, and the rear end of the integrated mandrel 62 is provided with a plurality of rubber bowls.

[0058] The tool is firstly put into the well during the construction, and the drilling fluid outside the drilling tool enters into the drilling tool through the circulating hole in the circulating unit 2 to realize the automatic grouting. When the tool is put into the designed well depth, the switch plug 5 is put in, the cement slurry is pumped, the switch plug 5 can isolate the drilling fluid and the cement slurry to avoid the flash setting of the cement slurry and affect the solidification quality of the cement slurry. The switch plug 5 firstly passes through the bumping unit 1, reaches the circulating unit 2, and is pressed to a certain pressure, then the first shear pin 29 on the circulating unit 2 is sheared, the sliding sleeve 22 is lowered from the first position to the second position, the first circulating hole 23 is closed, and the liquid injection hole 24 is opened. The pressure is continuously kept, the second shear pin 53 on the switch plug 5 is sheared, the guide head 54 is lowered, and enters below the sliding sleeve 22.

[0059] The cement slurry is started to be injected, and when the cement slurry is injected to the capsule 46, the fourth shear pin 48 on the capsule unit 4 is sheared, the circular guide head 49 is dropped, and the capsule 46 is extended.

[0060] When the cement slurry is injected to the designed amount, the bumping plug 6 is put in, the drilling fluid is injected, the bumping plug 6 can isolate the cement slurry and the drilling fluid, and at the same time, the residual cement slurry on the inner wall of the drilling tool is scraped, the bumping plug 6 reaches the bumping unit 1, is kept to a certain pressure, the fifth shear pin 13 is sheared, the bumping seat 12 and the bumping plug 6 are lowered, the second circulating hole 14 is opened, the circulation is re-established, and at the same time, the cement slurry injection is completed. The drilling tool is lifted, the shear pin in the releasing unit 3 is sheared, and the capsule 46, the shearing sleeve 41, the connecting sleeve 42, the fixing sleeve 43, the upper supporting sleeve 44 and the lower supporting sleeve 45 in the capsule unit 4 are dropped to the bottom of the well. When the shear pin in the releasing unit 3 fails to release, the capsule 46, the shearing sleeve 41, the connecting sleeve 42, the fixing sleeve 43, the upper supporting sleeve 44, the lower supporting sleeve 45, the shear pin and the back-off nut 32 are dropped to the bottom of the well.

[0061] In the description of the present application, the "lower" direction is the direction away from the wellhead, and the "upper" direction is the direction close to the wellhead.

[0062] Although the preferred embodiments of the present application have been described, those skilled in the art can make further changes and modifications to the embodiments once they know the basic inventive concept. Therefore, the appended claims are intended to be interpreted as including all the preferred embodiments and all the changes and / or modifications falling within the scope of the present application, and the changes and / or modifications made to the embodiments according to the present application should be covered within the protection scope of the present application.

Claims

1. A pack-off capsule for use in large size cavern formation drilling operations, characterized in that, The utility model relates to a cementing device, which comprises: a circulating unit (2) provided with a first circulating hole (23) and a liquid injection hole (24); a capsule unit (4) connected to the lower end of the circulating unit (2) and provided with a capsule (46) capable of being filled with cement slurry; and a pressure bumping unit (1) provided at the upper end of the circulating unit (2) and provided with a second circulating hole (14); wherein, the first circulating hole (23) of the circulating unit (2) is open and the liquid injection hole (24) is closed at the initial stage, the first circulating hole (23) is closed and the liquid injection hole (24) is open after the switch plug (5) is put in, and then the cement slurry poured in enters the capsule unit (4) through the liquid injection hole (24); after the pressure bumping plug (6) is put in, the second circulating hole (14) is open, circulation is established, the capsule unit (4) is separated from the circulating unit (2) by means of upward lifting or reverse buckling, and the releasing is completed. The circulating unit (2) comprises a circulating short section (21) provided with the first circulating hole (23) in the radial direction, the inside of the circulating short section (21) is provided with a sliding sleeve (22), the bottom of the sliding sleeve (22) is provided with the liquid injection hole (24), and the upper part of the sliding sleeve (22) is provided with a communication hole (27). In the initial state, the sliding sleeve (22) is in the first position, the first circulating hole (23) is in communication with the communication hole (27), and the liquid injection hole (24) is blocked by the circulating short section (21) and in the closed state; when the switch plug (5) is connected to the sliding sleeve (22) and pushes the sliding sleeve (22) to slide to the second position, the circulating hole is staggered with the communication hole (27), and the liquid injection hole (24) is open. In the initial state, the sliding sleeve (22) is connected to the circulating short section (21) through the first shear pin (29) in the first position, when the switch plug (5) is connected to the sliding sleeve (22), the pressure above it is built up, the first shear pin (29) is sheared off under the action of the pressure, and the sliding sleeve (22) is moved to the second position. The switch plug (5) comprises a mandrel (52), the outer wall of the rear end of the mandrel (52) is provided with a plurality of rubber bowls, the front end of the mandrel (52) is provided with a guide head (54), and the guide head (54) is connected to the mandrel (52) through a second shear pin (53).

2. The anti-sticking capsule for large size cavern formation drilling operations as claimed in claim 1, wherein, The releasing unit (3) is arranged between the capsule unit (4) and the circulating unit (2), by means of the releasing unit (3), the capsule unit (4) is separated from the circulating unit by means of upward lifting of the drilling tool under the action of the self-weight of the capsule unit (4), releasing is realized; or the capsule unit (4) is separated from the circulating unit (2) by means of rotating the drilling tool, and releasing is realized.

3. The anti-sticking capsule for large size cavern formation drilling operations as claimed in claim 2, wherein, The inner wall of the circulating short section (21) is provided with an inner step (26), and the outer wall of the sliding sleeve (22) is provided with an outer step (25), when the inner step (26) moves to the upper of the outer step (25), the sliding sleeve (22) is fixed in the second position.

4. The anti-sticking capsule for large size cavern formation drilling operations as claimed in claim 3 wherein, The bottom of the sliding sleeve (22) is provided with a receiving cavity (28), and the guide head (54) is separated from the mandrel (52) and moves into the receiving cavity (28).

5. The anti-sticking capsule for large size cavern formation drilling operations as claimed in claim 4 wherein, The sleeve pipe (47) is connected with the support fixing mechanism through the third shear pin (33), and the lower end of the support fixing mechanism is connected with the capsule (46). When the drilling tool is lifted, the third shear pin (33) is sheared, so that the sleeve pipe (47) is separated from the support fixing mechanism and the capsule (46).

6. The anti-sticking capsule for large size cavern formation drilling operations as claimed in claim 5 wherein, The lower end of the sleeve pipe (47) is provided with a circular guide head (49), and the circular guide head (49) is connected with the sleeve pipe (47) through the fourth shear pin (48).

7. The anti-sticking capsule for large size cavern formation drilling operations as claimed in claim 6 wherein, The support fixing mechanism includes a shear sleeve (41) connected with the third shear pin (33), the lower end of the shear sleeve (41) is provided with a connecting sleeve (42), the lower end of the connecting sleeve (42) is provided with an arc-shaped fixing sleeve (43), and the lower end of the fixing sleeve (43) is provided with a support sleeve. The support sleeve includes an upper support sleeve (44) and a lower support sleeve (45), and the capsule (46) is sealingly connected between the upper support sleeve (44) and the lower support sleeve (45).

8. The anti-sticking capsule for large size cavern formation drilling operations as claimed in claim 7, wherein, The releasing unit (3) includes a backoff joint (31) connected below the circulating unit (2), and a backoff nut (32) connected with the capsule unit (4). The backoff joint (31) is connected with the backoff nut (32) through threads, the backoff joint (31) is also connected with the sleeve pipe (47) through backoff threads, and the backoff nut (32) is connected with the sleeve pipe (47) and the support fixing mechanism through the third shear pin (33).

9. The anti-seizure capsule for use in drilling operations in large size cavernous formations according to claim 8, characterized in that, The impact pressure unit (1) includes an upper joint (11), the side wall of the upper joint (11) is provided with the second circulating hole (14) in the radial direction; the inside of the upper joint (11) is provided with an impact pressure seat (12), the impact pressure seat (12) is connected with the upper joint (11) through a fifth shear pin (13) in the initial state, and blocks the second circulating hole (14), when the impact pressure plug (6) is connected with the impact pressure seat (12) and is pressured, the fifth shear pin (13) is sheared, the impact pressure seat (12) moves and opens the second circulating hole (14).

10. The anti- sticking capsule for use in large size cavern formation drilling operations according to claim 9, characterized in that, The impact pressure plug (6) includes an integrated mandrel (62), and the rear end of the integrated mandrel (62) is provided with a plurality of rubber bowls.

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