A process string for pressurized operation of water injection wells

Abstract

This invention relates to the field of downhole operations technology for water injection wells in oilfields, and particularly to a process string for pressurized operations in water injection wells. This process string includes a casing, with tubing running inside the casing. From top to bottom, the tubing is provided with a blowout preventer (BOP) sleeve, a production tubing string, and a multi-functional BOP tailpipe. A screen pipe is located at the end of the tubing, and a guide cone is located below the screen pipe. The BOP sleeve contains a blowout preventer plug. The production tubing string includes several packers that divide the string into layers, each layer having a backflow preventer with a one-way valve structure. The multi-functional BOP tailpipe includes a lower valve body that provides blowout prevention and drainage, and an upper valve body that provides two-way valve function. The BOP sleeve, backflow preventer, and multi-functional BOP tailpipe achieve blowout prevention and drainage functions within the tubing above the tool section, the water distributor, and at the bottom of the tubing string. The cooperation of the upper and lower valve bodies provides a secondary blowout prevention function, effectively preventing blowout and draining the tubing during the string tripping process.

Description

Technical Field

[0001] This invention relates to the field of downhole operations technology for water injection wells in oilfields, and particularly to a process string for pressurized operations in water injection wells. Background Technology

[0002] In existing technologies, oilfields commonly use tubing for live-line operations by employing a tubing plug, a water distributor with a stopper nozzle, and a two-way valve in the tailpipe. This method controls the high pressure and overflow within the tubing during the pipe-raising process using the tubing plug and the two-way valve. During the lowering process, the two-way valve at the bottom of the tubing and the stopper nozzle control the overflow into the central pipe. However, the following problems remain: a tubing plug must be lowered before live-line operations, and it can only seal the tubing above the tool section; the placement of the plugging tool is uncertain, and locking it is difficult. Poor stability and easy to fly out under high pressure, therefore the pressure must be released when raising the tool, and it is not possible to keep it pressurized throughout the process; the method of inserting a plug with a dead nozzle into the water separator before operation is difficult to retrieve from wells with scale buildup in the tubing string and has a low success rate; in order to solve the blowout prevention problem in the tubing string above the tool end, the method of inserting a plug into the tubing string before operation is adopted, but it is difficult to insert the plug in high-pressure wells and has a low success rate; after adopting the above blowout prevention measures, the tubing string is prone to upward thrust and tubing string leakage during the raising and lowering of the tubing string due to the pressure from below. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] To address the shortcomings of existing technologies, this invention provides a process string for pressurized operations in water injection wells, solving the problems of existing technologies where pressure must be released when raising the tool, making it impossible to maintain pressure throughout the process; difficulties and low success rates in retrieving wells with scale buildup in the tubing; difficulties and low success rates in plugging high-pressure wells; and the tendency for the tubing to push up or move around during the raising and lowering process due to pressure from below.

[0005] (II) Technical Solution

[0006] To address the aforementioned problems, this invention provides a process tubing string for pressurized water injection well operations, comprising: a casing, an inner tubing, and below the tubing, sequentially arranged a blowout preventer (BOP) working cylinder, a production tubing string, and a multi-functional BOP tailpipe; a screen pipe is located at the end of the tubing, and a guide cone is located below the screen pipe; the BOP working cylinder contains a blowout preventer plug, which, together with the BOP working cylinder, opens the casing-oil channel; the production tubing string includes multiple packers with anti-mid-seating design to divide the production tubing string into several layers, each layer having an anti-backflow water distributor with a one-way valve function; the multi-functional BOP tailpipe includes a lower valve body for blowout prevention and drainage and an upper valve body for two-way valve function.

[0007] Preferably, the blowout preventer includes a sliding sleeve with a sliding sleeve retaining spring seat on top; the sliding sleeve is connected to the sliding sleeve retaining spring seat and then inserted into the outer sleeve; an upper sliding sleeve connector is provided above the sliding sleeve retaining spring seat and is inserted into the outer sleeve; the upper end of the outer sleeve is threadedly connected to the upper sliding sleeve connector, and the lower end is threadedly connected to the lower sliding sleeve connector; the sliding sleeve and the outer sleeve are fixed by a sliding sleeve pin; a cavity is provided between the lower end of the sliding sleeve and the upper end of the lower sliding sleeve connector inside the outer sleeve; the diameter of the middle part of the sliding sleeve is smaller than the diameters of the two ends, forming a groove; the inner diameter of the cavity inside the outer sleeve is larger than the maximum diameter of the sliding sleeve; a sliding sleeve retaining spring is provided on the outside of the top of the sliding sleeve; a toothed buckle is provided inside the outer sleeve, and an outer sleeve liquid outlet hole is provided on the corresponding part of the outer sleeve and the sliding sleeve groove.

[0008] Preferably, the blowout preventer inner plug includes an expansion sleeve, a blowout preventer inner plug sealing sleeve connected below the expansion sleeve, an inner plug connecting sleeve connected below the blowout preventer inner plug sealing sleeve, and a conical head connected below the inner plug connecting sleeve; the expansion sleeve has a spring claw at its top; the inner plug connecting sleeve has an axial guide groove inside, and a blowout preventer valve assembly is provided on the guide groove, the top of the blowout preventer valve assembly being an upward-facing cone; the bottom of the blowout preventer inner plug sealing sleeve is a conical surface that is smaller at the top and larger at the bottom, and it mates with the top of the blowout preventer valve assembly; a movable ball seat is fixed inside the inner plug connecting sleeve by a ball seat pin; the movable ball seat has an axial through hole in the middle, the upper end of the through hole being a guide surface that is larger at the top and smaller at the bottom; an inner plug steel ball is provided above the movable ball seat, the diameter of which mates with the guide surface at the upper end of the movable ball seat; the inner plug connecting sleeve has an inner plug outlet hole circumferentially provided on the portion below the movable ball seat; and the blowout preventer inner plug sealing sleeve has several blowout preventer inner plug sealing rings.

[0009] Preferably, the matching packer includes an upper central tube, the upper end of which is connected to an upper connector, and an upper outer cylinder is provided outside the upper connector; a first well-washing valve that can move up and down is provided between the upper outer cylinder and the upper central tube, and the lower end of the first well-washing valve is connected to a second well-washing valve; an inner sleeve is provided outside the upper central tube, the inner sleeve is located below the second well-washing valve, and a rubber sleeve assembly is fitted on the inner sleeve; the rubber sleeve assembly includes two side rubber sleeves (head and tail) and several middle rubber sleeves, with spacers between adjacent rubber sleeve sections; a packer pressure ring is provided below the rubber sleeve assembly, and the packer pressure ring is fixed to the end of the inner sleeve by a setting pin; a suspension body is provided below the inner sleeve, and a packer retaining spring is provided on the suspension body; a... The device includes a packer retaining sleeve, with its upper end connected to a packer pressure ring. The packer retaining sleeve has a toothed clasp inside. Below the packer retaining sleeve is a lower outer sleeve, and below the upper central tube of the packer is a lower central tube. The lower outer sleeve covers the lower central tube. A piston is positioned in the gap between the packer retaining sleeve, the upper central tube, the lower central tube, and the lower outer sleeve. Below the lower central tube is a cylinder liner, and below the cylinder liner is a lower packer connector. The lower connector is fitted onto the lower central tube, and the lower outer sleeve connects to the cylinder liner. The upper central tube has a first through hole corresponding to the position between the piston and the lower central tube, and the lower central tube has a second through hole corresponding to the position between the cylinder liner and the lower connector.

[0010] Preferably, the upper central tube has a third through hole at the position between the corresponding upper outer cylinder and the first well washing valve; the upper central tube has a well washing channel in the inner sleeve section, and the two ends of the inner sleeve have an upper well washing hole and a lower well washing hole respectively; the upper well washing hole and the lower well washing hole are both connected to the well washing channel.

[0011] Preferably, the anti-backflow water distributor includes a main body with an offset hole inside, and a blocker inside the offset hole; a ceramic ball is installed inside the nozzle of the blocker, and the diameter of the ceramic ball matches the inner diameter of the blocker to form a one-way valve structure; a straightener is connected above the main body, and an upper connector of the water distributor is provided above the straightener; an upper connecting sleeve is provided outside the straightener, with its upper end connected to the upper connector of the water distributor and its lower end connected to the main body; a lower connecting sleeve is connected below the main body, and a lower connector of the water distributor is connected below the lower connecting sleeve by a fastening screw; a lower guide body is provided inside the lower connector of the water distributor, and an upper guide sleeve is provided between the upper connector of the water distributor and the straightener, with an upper guide body inside the upper guide sleeve.

[0012] Preferably, the multi-functional blowout preventer includes an upper valve body and a lower valve body; the upper valve body includes an upper center tube of the blowout preventer, and the lower valve body includes a lower center tube of the blowout preventer; the lower end of the upper center tube of the blowout preventer is connected to the upper end of the lower center tube of the blowout preventer via a coupling; an upper sliding sleeve is provided inside the upper center tube of the blowout preventer and connected to it via a first pin of the blowout preventer; a sealing sleeve is provided outside the upper center tube of the blowout preventer and connected to it via a second pin of the blowout preventer; a toothed sleeve is connected above the sealing sleeve, a retaining ring is provided inside the toothed sleeve, and a retaining ring that cooperates with the retaining ring is provided at the top of the upper center tube of the blowout preventer. The device includes a seat; an upper connector for the blowout preventer tailpipe is provided above the toothed sleeve, and a ball baffle with a through hole is provided inside the upper connector for the blowout preventer tailpipe; the top of the upper sliding sleeve is inserted into the upper connector for the blowout preventer tailpipe, and the top has a downward guiding structure; a blowout preventer tailpipe steel ball is provided between the upper sliding sleeve and the upper connector for the blowout preventer tailpipe; a pressure ring is provided below the sealing sleeve, and a pressure ring sealing ring is provided between the sealing sleeve and the pressure ring; the bottom end of the pressure ring is connected to the upper center tube of the blowout preventer tailpipe; an upper center tube through hole is provided on the side of the upper center tube of the blowout preventer tailpipe corresponding to the lower pressure ring, and an upper sliding sleeve through hole is provided above the upper center tube through hole on the upper sliding sleeve.

[0013] Preferably, the lower valve body includes a lower central tube of the blowout preventer, a guide tube fixed outside the lower central tube, the two ends of the guide tube contacting the lower central tube of the blowout preventer, and a gap between the middle part and the lower central tube of the blowout preventer; an upper retaining ring is provided at the upper end and a lower retaining ring is provided at the lower end inside the lower central tube of the blowout preventer, and both the upper and lower retaining rings are provided with axial through holes; a lower sliding sleeve is provided above the lower retaining ring, and a lower central tube spring is provided between the upper sliding sleeve and the upper retaining ring; an upward guide structure is provided above the lower sliding sleeve, and a lower sliding sleeve steel ball is provided inside; a lower sliding sleeve spring is provided below the lower sliding sleeve steel ball; a lower sliding sleeve through hole is provided at the lower end of the side of the lower sliding sleeve; the upper and lower ends of the side of the lower central tube of the blowout preventer corresponding to the gap between the guide tube are respectively provided with an upper connecting hole and a lower connecting hole.

[0014] (III) Beneficial Effects

[0015] The injection well pressurized operation process string provided by this invention achieves secondary blowout prevention before string pulling by incorporating a secondary blowout prevention structure on the multi-functional blowout preventer tailpipe, enhancing the overall safety of pressurized operations during construction and eliminating the need for pressure relief. The blowout preventer working cylinder and blowout preventer plug work together to seal the liquid inside the lower end of the string. Multiple matching packers stratify the production string, and the one-way valve structure within the blowout preventer tailpipe allows the injection well to resume normal production after string running by pressurizing at the wellhead. The one-way valve structure in the anti-backflow distributor ensures that the device can achieve pressure balance without ejection or overflow. The anti-mid-running design in the matching packers ensures the smooth running of the water string to the intended position. Attached Figure Description

[0016] Figure 1It is a structural schematic diagram of the work string for pressure - operated well injection operation of the present invention;

[0017] Figure 2 It is a structural diagram of the blowout - prevention working barrel of the work string for pressure - operated well injection operation of the present invention;

[0018] Figure 3 It is a structural diagram of the blowout - prevention internal plug of the work string for pressure - operated well injection operation of the present invention;

[0019] Figure 4 It is a structural diagram of the matching packer of the work string for pressure - operated well injection operation of the present invention;

[0020] Figure 5 It is a structural diagram of the anti - reflux water distributor of the work string for pressure - operated well injection operation of the present invention;

[0021] Figure 6 It is a structural diagram of the plug of the work string for pressure - operated well injection operation of the present invention;

[0022] Figure 7 It is a structural diagram of the multi - functional blowout - prevention tail pipe of the work string for pressure - operated well injection operation of the present invention.

[0023] The components include: 1. Casing; 2. Oil pipe; 3. Blowout preventer working cylinder; 4. Matching packer; 5. Anti-backflow water distributor; 6. Multi-functional blowout preventer tailpipe; 7. Screen pipe; 8. Guide cone; 9. Upper connector of sliding sleeve; 10. Outer sleeve; 11. Sliding sleeve retaining ring; 12. Sliding sleeve retaining ring seat; 13. Sliding sleeve; 14. Fixing pin; 15. Lower connector of sliding sleeve; 16. Expansion sleeve; 17. Inner seal sleeve of blowout preventer; 18. Blowout preventer assembly; 19. Blowout preventer seal ring; 20. Inner plug steel ball; 21. Movable ball seat; 22. Ball seat pin; 23. Inner plug connecting sleeve; 24. Conical head; 25. Packer upper connector; 26. Upper outer cylinder; 27. Packer upper center tube; 28. First well-washing valve; 29. ​​Second well-washing valve; 30. Sealing seat; 31. Side rubber sleeve; 32. Diaphragm; 33. Middle rubber sleeve; 34. Inner sleeve; 35. Unsealing pin; 36. Packer pressure ring; 37. Setting pin; 38. Suspension body; 39. Packer retaining ring; 40. Packer retaining ring sleeve; 41. Piston; 42. Packer lower center tube; 43. Lower outer sleeve; 44. Cylinder liner; 45. Packer lower connector; 46. Water distributor upper connector; 47. Upper connecting sleeve; 48. Centralizing body; 49. Main body; 50. Lower connecting sleeve; 51. Lower connector of water distributor; 52. Lower guide body; 53. Plug; 54. Ceramic ball; 55. Fastening screw; 56. Upper guide sleeve; 57. Upper guide body; 58. Upper connector of blowout preventer tailpipe; 59. Blowout baffle plate; 60. Blowout preventer tailpipe steel ball; 61. Toothed sleeve; 62. Upper sliding sleeve; 63. Snap ring seat; 64. Snap ring; 65. Sealing sleeve; 66. First pin of blowout preventer; 67. Second pin of blowout preventer; 68. Upper center tube of blowout preventer tailpipe; 69. Pressure ring sealing ring; 70. Pressure ring; 71. Snap ring; 72. Guide head; 73. Coupling; 74. Upper retaining ring; 75. Lower center tube of blowout preventer tailpipe; 76. Lower center tube spring; 77. Guide tube; 78. Lower sliding sleeve; 79. Lower sliding sleeve steel ball; 80. Lower sliding sleeve spring; 81. Lower retaining ring. Detailed Implementation

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] In the description of this invention, it is necessary to understand that the orientation or positional relationship indicated by terms such as "upper", "lower", "inner", "outer", "top", and "bottom" are based on the orientation or positional relationship shown in the accompanying drawings. The purpose is only to facilitate the description of this invention and to simplify the description. It is not intended to indicate or imply that the component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0026] like Figure 1-6 As shown, the present invention provides a process tubing string for pressurized operation of water injection wells, specifically including: casing 1 and tubing 2, the tubing 2 being inserted inside casing 1, and the tubing 2 being provided with a blowout preventer working cylinder 3, a production tubing string and a multi-functional blowout preventer tailpipe 6 in sequence from top to bottom, the end of the tubing 2 being provided with a screen pipe 7, and a guide cone 8 being provided below the screen pipe 7.

[0027] The production tubing includes multiple packers 4 that divide the production tubing into several layers. Each layer of the production tubing is equipped with an anti-backflow water distributor 5 to perform layered water injection and anti-blowout treatment on the production tubing, thereby improving the anti-blowout capability of the device. The anti-blowout working cylinder 3 is equipped with an anti-blowout inner plug.

[0028] It should be noted that the anti-backflow water distributor 5 is equipped with a blocker 53, which has a one-way valve structure that can inject liquid into the production column. When the liquid moves in the reverse direction, the one-way valve structure can prevent the liquid from flowing and achieve the anti-spray function.

[0029] like Figure 2 As shown, the blowout preventer working cylinder 3 includes a sliding sleeve 13. The upper end of the sliding sleeve 13 is threadedly connected to a sliding sleeve retainer seat 12 for cooperating with the blowout preventer inner plug. After the sliding sleeve 13 is connected to the sliding sleeve retainer seat 12, it is inserted into the outer sleeve 10. A sliding sleeve upper connector 9 is provided above the sliding sleeve retainer seat 12 for connecting the oil pipe 2. The sliding sleeve 13 and the outer sleeve 10 are connected by a fixing pin 14. When the downward force on the sliding sleeve 13 exceeds the stress limit of the fixing pin 14, the fixing pin 14 shears off, and the sliding sleeve 13 moves downward. A sliding sleeve lower connector 15 is provided below the sliding sleeve 13 for connecting with the components below.

[0030] The diameter of the side of the sliding sleeve 13 is smaller than the diameter of both ends, forming a groove on the side of the sliding sleeve 13. The lower end of the outer sleeve 10 is connected to the lower connector 15 of the sliding sleeve. A cavity is provided between the lower connector 15 of the sliding sleeve and the sliding sleeve 13 inside the outer sleeve 10. The diameter of the cavity is larger than the diameter of the sliding sleeve. When the sliding sleeve 13 moves downward, part of the groove enters the cavity along with the sliding sleeve 13. The side of the outer sleeve 10 is provided with an outer sleeve liquid outlet hole. When the groove enters the cavity, the outer sleeve liquid outlet hole coincides with part of the groove. At the same time, the lower part of the sliding sleeve 13 still does not contact the lower connector 15 of the sliding sleeve. At this time, the inside of the blowout preventer cylinder 3 is connected to the oil sleeve annulus, establishing a liquid flow channel.

[0031] It should be noted that the top of the sliding sleeve 13 is provided with a sliding sleeve retaining spring 11, and the inside of the outer sleeve 10 is provided with a toothed buckle. When the sliding sleeve 13 moves downward, the sliding sleeve retaining spring 11 and the toothed buckle cooperate to fix the sliding sleeve 13. At this time, there is still a distance between the bottom of the sliding sleeve 13 and the top of the upper connector 15 of the sliding sleeve, ensuring the stability and normal operation of the liquid flow channel.

[0032] In this invention, the blowout preventer working cylinder 3 is provided with a blowout preventer inner plug, which includes an expansion sleeve 16. The top of the expansion sleeve 16 is provided with a spring claw, which cooperates with the sliding sleeve retaining spring seat 12 to fix the blowout preventer inner plug. The bottom of the expansion sleeve 16 is connected to the blowout preventer inner plug sealing sleeve 17. The blowout preventer inner plug sealing sleeve 17 is provided with multiple blowout preventer inner plug sealing rings 19 to ensure the sealing of the device. The bottom of the blowout preventer inner plug sealing sleeve 17 is connected to the inner plug connecting sleeve 23. The top of the inner plug connecting sleeve 23 is provided with a blowout preventer valve assembly 18. The upper end of the blowout preventer valve assembly is an upward cone shape. The lower end face of the blowout preventer inner plug sealing sleeve 17 cooperates with the top of the blowout preventer valve assembly 18 to form a one-way valve structure. When the liquid flows from top to bottom, it can flow freely. When the liquid moves from bottom to top, the blowout preventer valve assembly 18 moves upward and cooperates with the inner plug connecting sleeve 23 to prevent the liquid from flowing upward. The inner plug connecting sleeve 23 is fixed with a movable ball seat 21 by a ball seat pin 22. The movable ball seat 21 is provided with an inner plug steel ball 20. The upper surface of the movable ball seat 21 cooperates with the inner plug steel ball 21 to form a one-way valve structure. When the liquid flows from top to bottom, the inner plug steel ball 21 blocks the flow of the liquid.

[0033] The inner plug connecting sleeve 23 below the movable ball seat 21 is provided with an inner plug liquid outlet. After the blowout preventer working cylinder 3 establishes a liquid flow channel, when the liquid pressure on the inner plug steel ball 20 is greater than the stress limit of the ball seat pin 22, the ball seat pin 22 is cut off, and the movable ball seat 21 moves downward. At this time, the inner plug liquid outlet on the inner plug connecting sleeve 23 is connected to the inside of the blowout preventer inner plug to form a liquid channel. After that, when the tubing string is raised, the liquid in the tubing string enters the annulus through the blowout preventer inner plug and the blowout preventer working cylinder 3 to form a blockage and splash prevention structure.

[0034] It should be noted that the blowout preventer plug and the blowout preventer working cylinder 3 are designed separately. At the beginning of the operation, the blowout preventer plug is not installed on the blowout preventer working cylinder 3. Before the tubing string is to carry out this operation, the valve at the wellhead is opened to drop the blowout preventer plug. Under the push of the water injection pressure, the blowout preventer plug moves down and contacts the blowout preventer working cylinder 3 and works.

[0035] like Figure 4As shown, the matching packer 4 includes a packer upper central tube 27, the upper end of which is connected to a packer upper connector 25 for connection with the upper component; an upper outer cylinder 26 is provided outside the packer upper connector 25; a first well-washing valve 28 that can move up and down is provided between the upper outer cylinder 26 and the packer upper central tube 27, the lower end of the first well-washing valve 28 is connected to a second well-washing valve 29, and the packer upper central tube 27 has a connecting hole at the position corresponding to the position between the first well-washing valve 28 and the packer upper connector 25, through which liquid enters the first well-washing valve. The packer 28 and the second well-washing valve 29 clean the well interior; an inner sleeve 34 is provided outside the central tube 27 of the packer, located below the second well-washing valve 29, for installing the rubber sleeve assembly; the rubber sleeve assembly is fitted on the inner sleeve 34, the rubber sleeve assembly includes two side rubber sleeves 31 and several middle rubber sleeves 33, with spacers 32 between adjacent rubber sleeves to prevent the rubber sleeves from squeezing or colliding with each other and causing damage; a packer pressure ring 36 is provided below the rubber sleeve assembly, and the packer pressure ring 36 is fixed to the end of the inner sleeve 34 by a setting pin 37; the inner sleeve Below the tube 34, a suspension body 38 is provided, and a packer retainer 39 is provided on the suspension body 38. The suspension body 38 is connected to the inner sleeve 34 via a release pin 35. Outside the suspension body 38, a packer retainer 39 sleeve 40 is provided. The upper end of the packer retainer 39 sleeve 40 is connected to a packer pressure ring 36, and a toothed buckle is provided inside the packer retainer 30 sleeve. Below the packer retainer 39 sleeve 40, a lower outer sleeve 43 is provided. Below the upper central tube 27 of the packer, a lower central tube 42 of the packer is provided. The lower outer sleeve 43 is fitted over the lower central tube 42 of the packer. A piston 41 is installed in the gap between the upper central tube 27, the lower central tube 42, and the lower outer sleeve 43 of the packer; a cylinder liner 44 is installed below the lower central tube 42 of the packer, and a lower connector 45 of the packer is installed inside the lower cylinder liner 44; the lower connector 45 of the packer is sleeved on the lower central tube 42 of the packer, and the lower outer sleeve 43 is connected to the cylinder liner 44; the upper central tube 27 of the packer has a first through hole at the position between the piston 41 and the lower central tube 42 of the packer, and the lower central tube 42 of the packer has a second through hole at the position between the cylinder liner 44 and the lower connector 45 of the packer.

[0036] When the device is pressurized, high-pressure liquid enters the annulus between the upper central tube 27 of the packer, the lower central tube 42 of the packer, the piston 41, and the lower outer sleeve 43 through the first through hole. At this time, the liquid pressure pushes the piston 41 to push the packer retaining sleeve 40 and the packer pressure ring 36 upward. At the same time, high-pressure liquid enters the annulus between the lower central tube 42 of the packer, the cylinder liner 44, and the lower connector 45 of the packer through the second through hole, pushing the cylinder liner 44, the lower outer sleeve 43, and the packer retaining sleeve 40, thereby pushing the packer pressure ring 36 upward. When the thrust on the packer pressure ring 36 exceeds the maximum stress limit of the release pin 35, the release pin 35 is cut off, and the packer pressure ring 36 moves upward to squeeze the rubber sleeve assembly for setting. At this time, the packer retaining sleeve 40 moves upward. When the toothed buckle inside the packer retaining sleeve 40 engages with the packer retaining spring 39, the state of the packer retaining sleeve 40 and the rubber sleeve assembly is fixed, and the device achieves setting.

[0037] Among them, the setting pin 37 plays the role of preventing mid-way setting during operation. Only when the pressure is greater than its maximum shear stress will the setting pin 37 shear off, and the rubber sleeve assembly can carry out normal setting work, ensuring that mid-way setting will not occur during the lowering of the device, and ensuring that the device is smoothly lowered to the setting position.

[0038] It should be noted that the upper central tube 27 is provided with a third through hole at the position between the corresponding upper outer cylinder 26 and the first well washing valve 28; the upper central tube 27 is provided with a well washing channel at the part where the inner sleeve 34 is installed, and the two ends of the inner sleeve 34 are respectively provided with an upper well washing hole and a lower well washing hole; the upper well washing hole and the lower well washing hole are both connected to the well washing channel.

[0039] like Figure 5 As shown, the anti-backflow water distributor 5 includes a main body 49, with a straightening body 48 connected to the upper part of the main body 49, and an upper guide sleeve 56 connected to the upper end of the straightening body 48; an upper guide body 57 is provided inside the upper guide sleeve 56, and the upper end of the upper guide sleeve 56 is connected to the upper connector 46 of the water distributor; an upper connecting sleeve 47 is provided outside the straightening body 48, with the upper end of the upper connecting sleeve 47 connected to the upper connector 46 of the water distributor and the lower end connected to the main body 49; a lower connecting sleeve 50 is provided at the lower end of the main body 49, and a lower connector 51 of the water distributor is provided at the lower end of the lower connecting sleeve 50, and the lower connector 51 of the water distributor is connected to the lower connecting sleeve 50 by a fastening screw 55; a lower guide body 52 is provided inside the lower connector 51 of the water distributor; an off-center hole is provided inside the main body 49, and a blocker 53 is placed in the off-center hole; a ceramic ball 54 is provided inside the water nozzle of the blocker 53.

[0040] The ceramic ball 54 fits into the inner surface of the inlet of the plug 53. When water is injected through the plug 53, the liquid enters the surrounding annular space through the nozzle of the plug 53. Simultaneously, when the liquid flows back in the annular space, the ceramic ball 54 is pushed by the liquid to block the inlet of the plug 53, preventing backflow and forming a one-way valve structure. This structure allows the anti-backflow water distributor 5 to both inject water normally and prevent backflow, thus preventing spraying.

[0041] like Figure 6 As shown, the multi-functional blowout preventer 6 includes an upper central tube 68 and a lower central tube 75. An upper sliding sleeve 62 is connected to the upper central tube 68 via a first pin 66 of the blowout preventer cylinder. The upper end of the upper sliding sleeve 62 has a downward-facing guide structure, and a matching blowout preventer steel ball 60 is provided at the upper end of the upper sliding sleeve 62. A sealing sleeve 65 is provided outside the upper central tube 68 and connected via a second pin 67 of the blowout preventer cylinder. An upper connector 58 of the blowout preventer is connected above the upper sliding sleeve 62. The upper connector 58 is equipped with a ball baffle 59 with a through hole. The ball baffle 59 and the blowout preventer tailpipe steel ball 60 are separated by a gap, which ensures that the blowout preventer tailpipe steel ball 60 can move freely while preventing the blowout preventer tailpipe steel ball 60 from flowing out of the multi-functional blowout preventer tailpipe 6 with the liquid. The upper end of the sealing sleeve 65 is connected to the toothed sleeve 61, and the upper end of the toothed sleeve 61 is connected to the upper connector 58 of the blowout preventer tailpipe. The upper center tube 68 of the blowout preventer tailpipe is equipped with a pressure ring 70, which is located below the sealing sleeve 65. A pressure ring sealing ring 69 is provided between the pressure ring 70 and the sealing sleeve 65.

[0042] The upper sliding sleeve 62 and the upper central tube 68 of the blowout preventer (BOP) are respectively provided with circumferentially arranged upper sliding sleeve through holes and upper central tube through holes. The upper central tube through hole of the upper central tube 68 of the BOP is located below the pressure ring 70, and the upper sliding sleeve through hole of the upper sliding sleeve 62 is located above the upper central tube through hole of the upper central tube 68 of the BOP. When the tubing string is lowered to the predetermined position, the tubing is pressurized, and the high-pressure liquid pushes the BOP steel ball 60 to drive the upper sliding sleeve 62 downward. When the pressure exceeds the maximum stress limit of the first pin 66 of the BOP, the first pin 66 of the BOP shears off, and the upper sliding sleeve 62 slides to the upper end face of the upper central tube 68 of the BOP. At this time, the upper sliding sleeve through hole and the upper central tube through hole are radially opposite, and the interior of the multi-functional BOP 6 is connected to the annulus of the tubing, establishing a liquid channel to meet the well washing requirements during production.

[0043] During well washing, when the packer 4 is set, high-pressure liquid flows out from the third through hole, pushing the first washing valve 28 and the second washing valve 29 downward to block the upper washing hole of the inner casing 34, preventing the liquid in the well from entering from the lower washing hole and flowing back out of the wellhead through the washing channel. After the packer 4 is set, when well washing is carried out, high-pressure washing liquid is injected into the surrounding annulus. At this time, the second washing valve 29 is pushed upward. Due to the pressure difference, the first washing valve 28 and the second washing valve 29 move upward. At this time, the upper washing hole opens, and the washing liquid enters the upper washing hole and flows out from the lower washing hole through the washing channel. Then, the liquid in the annulus enters the tubing string through the liquid channel of the multi-functional blowout preventer 6 and flows out from the top of the tubing string to achieve the well washing effect.

[0044] It should be noted that the upper sliding sleeve 62 is provided with a guide head 72 at the bottom end, and a retaining spring 71 is provided above the guide head 72. When the upper sliding sleeve 62 moves downward, the retaining spring 71 slides out of the upper center tube 68 of the blowout preventer and pops out and locks at the bottom end of the upper center tube 68 of the blowout preventer, fixing the upper sliding sleeve 62 and ensuring the stability of the liquid channel of the multi-functional blowout preventer 6.

[0045] In this invention, the lower center tube 75 of the blowout preventer is connected to the upper center tube 68 of the blowout preventer via a coupling 73 at the connection point; a guide tube 77 is provided outside the lower center tube 75, the inner diameter of the middle part of the guide tube 77 is larger than that of the lower center tube 75, forming a gap between the guide tube 77 and the lower center tube 75; the portion of the lower center tube 75 corresponding to the gap between the guide tube 77 and the guide tube 77 is provided with an upper connecting hole and a lower connecting hole at its upper and lower ends, respectively; the blowout preventer... The lower center tube 75 has an upper retaining ring 74 at its upper end and a lower retaining ring 81 at its lower end; the lower center tube 75 of the blowout preventer has a sliding sleeve 78 that can move up and down, and the side wall of the sliding sleeve 78 has a sliding sleeve flow hole corresponding to the position of the lower flow hole; the upper end of the sliding sleeve 78 has an upward guide structure, and the sliding sleeve 78 has a sliding sleeve steel ball 79 inside; the lower center tube spring 76 is provided between the sliding sleeve 78 and the upper retaining ring 74, and the sliding sleeve spring 80 is provided between the sliding sleeve steel ball 79 and the lower retaining ring 81.

[0046] During the assembly and lowering of the device, liquid enters the lower central tube 75 of the blowout preventer from below, passes through the lower retaining ring 81 into the lower sliding sleeve 78, and pushes the steel ball 79 of the lower sliding sleeve upward to block the upper port of the lower sliding sleeve 78, preventing liquid from directly rushing into the concentrator and causing splashing. Simultaneously, when the liquid pressure below is high, the liquid pushes the steel ball 79 and the lower sliding sleeve 78 upward to compress the lower central tube spring 76. During this upward movement, the flow hole of the lower sliding sleeve coincides with the lower connecting hole of the lower central tube 75 of the blowout preventer. At this time, the liquid enters the gap between the guide pipe 77 and the lower central tube 75 of the blowout preventer through the lower flow hole, and then enters the upper sliding sleeve 78 inside the lower central tube 75 of the blowout preventer through the upper connecting hole. The gravity of the liquid above the lower sliding sleeve 78 is used to balance the upward pressure of the liquid below and appropriately reduce the pressure of the liquid below, ensuring the blowout prevention performance and stability of the device. At the same time, by guiding some of the liquid below closer to the lower central tube 75 of the blowout preventer, the function of preventing pipe cross-flow is achieved. As the liquid pressure below continues to increase, the sliding sleeve 78 continues to move upward, and the flow passage of the sliding sleeve separates from the lower connecting hole. At this time, the liquid no longer enters the lower central tube 75 of the blowout preventer tailpipe, thus realizing the function of re-venting and preventing blowout at the bottom of the tube column.

[0047] In this invention, a screen tube 7 is provided at the bottom of the tubing to filter out large impurities in the liquid below, preventing blockage or jamming inside the tubing; a guide cone 8 is provided below the screen tube 7 to assist the tubing in its lowering, reduce the resistance to lowering the tubing, and improve the working efficiency of the device.

[0048] It should be noted that each component in this invention has several sealing rings at the contact points to ensure the sealing of the device during use, ensure the normal operation of the device, and improve the practicality of the device.

[0049] The injection well pressurized operation process string provided by this invention enables a second blowout preventer before string running, enhancing the overall safety of pressurized operations during construction without the need for depressurization. It achieves three-stage blowout prevention: the tool section, the area above the tool section, and the area below the tool section. Multiple matching packers layer the production string, and the one-way valve structure within the blowout preventer tailpipe allows for wellhead pressurization after string running to restore normal production. The one-way valve structure in the anti-backflow distributor ensures pressure balance during drainage without ejection or overflow. The anti-mid-running design in the matching packers ensures the smooth running of the water string to the intended location. The specific operation process of this device is as follows:

[0050] Step 1: Connect the oil pipes and components to the device from bottom to top, with the screen pipe and guide cone connected to the end of the bottommost oil pipe.

[0051] Step 2: Lower the assembled tubing string into the well. During the lowering process, the multi-functional blowout preventer (BOP) is initially sealed. As it extends into the wellbore, the pressure gradually increases, and the pressure of the well fluid below also gradually increases. The well fluid enters the tubing string through the screen pipe and moves upward into the sliding sleeve, pushing the steel ball and the sliding sleeve upward and compressing the lower center tube spring. When the through hole of the sliding sleeve gradually coincides with the lower flow hole of the lower center tube of the BOP, a small amount of well fluid enters the gap between the lower center tube and the guide pipe of the BOP through the lower flow hole, and then flows through the upper flow hole of the lower center tube of the BOP. As the fluid flows into the blowout preventer (BOP) tailpipe through the flow hole, the well pressure continues to rise. When the through hole of the sliding sleeve completely overlaps with the lower flow hole of the lower central tube of the BOP tailpipe, the flow rate of the well fluid flowing into the multi-functional BOP tailpipe is at its maximum. As the downhole pressure continues to rise, the sliding sleeve continues to move upward, and the through hole of the sliding sleeve and the lower flow hole are misaligned, preventing the fluid from entering the multi-functional BOP tailpipe. This ensures that the fluid level in the tubing is always lower than the fluid level in the annulus, achieving the effect of blowout prevention. At the same time, the gravity of the fluid entering the tubing string can appropriately balance the upward force exerted on the tubing string when it is lowered into the well, achieving the effect of preventing tubing from running through.

[0052] Step 3: After the tubing string reaches the predetermined position, pressurize the tubing. The high-pressure fluid pushes the blowout preventer (BOP) liner ball and upper sliding sleeve downwards, shearing the first pin of the BOP. The upper sliding sleeve and the flow space of the upper center tube of the BOP are radially connected. The functional BOP liner connects the tubing string to the annulus of the tubing casing, providing conditions for well washing during production. The BOP liner ball sits downwards above the upper sliding sleeve, and the bottom of the multi-functional BOP liner is sealed. As the pressure inside the tubing increases, the high-pressure fluid enters the upper center tube and lower center tube of the packer through the first through-hole of the packer's upper center tube. In the annulus between the piston and the lower outer sleeve, fluid simultaneously enters the annulus between the lower central tube of the packer, the cylinder liner, and the lower connector of the packer through the second through hole of the upper central tube of the packer. This pushes the piston and cylinder liner, the lower outer sleeve, and the cylinder liner, which in turn pushes the retaining ring and the packer pressure ring upwards, shearing the setting pin and compressing the rubber sleeve assembly. At the same time, the suspension body moves downwards, and the packer moves down to cooperate with the packer retaining ring to fix the packer, setting the packer. Simultaneously, fluid flows out from the third through hole, pushing the first and second well-washing valves downwards to block the upper well-washing hole and seal the well-washing passage. During backwashing, pressure is applied to the annulus, and the high-pressure fluid enters through the flow holes of the upper central tube and the upper sliding sleeve of the blowout preventer, pushing upwards to open the steel ball of the blowout preventer and entering the tubing string to return to the wellhead.

[0053] Step 4: Perform well washing. Add high-pressure well washing fluid into the annulus of the tubing string. At this time, the high-pressure well washing fluid pushes the second well washing valve upward, and the first and second well washing valves move upward. The upper well washing orifice opens, and the well washing fluid enters the well washing channel through the upper well washing orifice and flows out from the lower well washing orifice. At this time, the fluid in the annulus is squeezed by the well washing fluid and enters the tubing string through the liquid channel of the multi-functional blowout preventer tailpipe, moving upward and finally being discharged from the wellhead, forming a passage and achieving the well washing effect.

[0054] Step 5: Before resuming operations, open the wellhead test valve and insert the blowout preventer (BOP). Under the pressure of water injection, the BOP descends to the BOP working barrel. The BOP continues to descend and enters the BOP working barrel. The expansion sleeve and the sliding sleeve retainer seat engage to fix the BOP to the BOP working barrel. High-pressure liquid pushes the BOP steel ball and the movable ball seat, thereby pushing the BOP and the sliding sleeve downwards. The fixing pin shears the sliding sleeve and it continues to descend. The sliding sleeve retainer and the toothed buckle inside the outer sleeve engage to fix the sliding sleeve. At this time, the internal cavity of the outer sleeve and the groove on the side of the sliding sleeve are connected to form a liquid channel. Continue pressurizing, and the movable ball seat shears the ball seat pin and continues to descend. The outlet of the BOP opens and connects with the liquid channel of the BOP working barrel. At this time, the tubing string is pulled up. The liquid in the tubing string is diverted to the annulus through the outlet of the BOP and the liquid pipeline of the BOP working barrel, and will not flow out of the wellhead from the tubing, thus achieving the function of sealing the liquid in the lower end of the tubing string of the BOP and tool section.

[0055] Step Six: After the work is completed, the tubing string is raised to remove the packer. At this time, the upper connector of the packer moves upward, causing the rubber sleeve to move upward, thereby restoring the rubber sleeve to its original position and releasing the packer. Then, the tubing string is lowered to explore the bottom of the artificial well. After the tubing string hits the bottom of the well, the lower center tube of the blowout preventer moves the coupling, circlip seat, and circlip upward, cutting the second pin of the blowout preventer. The upper center tube of the blowout preventer moves upward. At this time, the flow passage between the upper center tube of the blowout preventer and the upper sliding sleeve is misaligned, the liquid passage is closed, the circlip engages with the toothed buckle on the sleeve to fix the device, the sliding stops, the liquid passage between the multi-functional blowout preventer and the annulus is closed, and the bottom of the tubing string achieves the function of re-venting and preventing blowout.

[0056] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A tubing string for pressurized operation of a water injection well, characterized in that, include: A casing (1) is provided, with an oil pipe (2) running through it. Below the oil pipe (2) are arranged a blowout preventer working cylinder (3), a production tubing, and a multi-functional blowout preventer tailpipe (6). At the end of the oil pipe (2) is a screen pipe (7), and below the screen pipe (7) is a guide cone (8). The blowout preventer working cylinder (3) is provided with a blowout preventer plug. The blowout preventer plug and the blowout preventer working cylinder (3) work together to open the oil casing channel. The production tubing includes multiple matching packers (4) with anti-mid-seating design to divide the production tubing into several layers. Each layer is provided with an anti-backflow water distributor (5) with a one-way valve function. The multi-functional blowout preventer tailpipe (6) includes a lower valve body that plays the role of blowout prevention and drainage and an upper valve body that plays the role of a two-way valve. The blowout preventer (3) includes a sliding sleeve (13), and a sliding sleeve retainer seat (12) is provided above the sliding sleeve (13). After the sliding sleeve (13) is connected to the sliding sleeve retainer seat (12), it is inserted into the outer sleeve (10). A sliding sleeve upper connector (9) is provided above the sliding sleeve retainer seat (12), and the sliding sleeve upper connector (9) is inserted into the outer sleeve (10). The upper end of the outer sleeve (10) is threadedly connected to the sliding sleeve upper connector (9), and the lower end is threadedly connected to the sliding sleeve lower connector (15). The sliding sleeve (13) and the outer sleeve (10) are connected by the sliding sleeve. The pin (14) is used for fixing; a cavity is provided between the lower end of the inner sleeve (13) and the upper end of the lower connector (15) of the sleeve in the outer sleeve (10); the diameter of the middle part of the sleeve (13) is smaller than the diameter of the two ends to form a groove; the inner diameter of the cavity part inside the outer sleeve (10) is larger than the maximum diameter of the sleeve (13); a sleeve retaining spring (11) is provided on the outside of the top of the sleeve (13); a toothed buckle is provided inside the outer sleeve (10), and an outer sleeve liquid outlet hole is provided on the corresponding part of the groove of the outer sleeve (10) and the sleeve (13); The blowout preventer inner plug includes an expansion sleeve (16), a blowout preventer inner plug sealing sleeve (17) connected below the expansion sleeve (16), an inner plug connecting sleeve (23) connected below the inner plug sealing sleeve (17), and a conical head (24) connected below the inner plug connecting sleeve (23). The expansion sleeve (16) has a spring claw at its top. The inner plug connecting sleeve (23) has an axial guide groove inside, and a blowout preventer valve assembly (18) is provided on the guide groove. The top of the blowout preventer valve assembly (18) is an upward-pointing cone. The bottom of the blowout preventer inner plug sealing sleeve (17) is a conical surface that is smaller at the top and larger at the bottom, and is connected to the blowout preventer valve. The top of the component (18) is fitted; the movable ball seat (21) is fixed inside the inner plug connecting sleeve (23) by a ball seat pin (22); the movable ball seat (21) has an axial through hole in the middle, and the upper end of the through hole is a guide surface that is larger at the top and smaller at the bottom; an inner plug steel ball (20) is provided above the movable ball seat (21), and its diameter matches the guide surface at the upper end of the movable ball seat (21); the inner plug connecting sleeve (23) has an inner plug liquid outlet hole in the circumferential direction corresponding to the part below the movable ball seat (21); the anti-blowout inner plug sealing sleeve (17) is provided with several anti-blowout inner plug sealing rings (19).

2. The injection well pressurized operation process tubing string according to claim 1, characterized in that, The matching packer (4) includes a packer upper central tube (27), the upper end of which is connected to a packer upper connector (25), and an upper outer cylinder (26) is provided outside the packer upper connector (25); a first well-washing valve (28) that can move up and down is provided between the upper outer cylinder (26) and the packer upper central tube (27), and the lower end of the first well-washing valve (28) is connected to a second well-washing valve (29); an inner sleeve (34) is provided outside the packer upper central tube (27), and the inner sleeve (34) is located at the second well-washing valve. (29) Below, a rubber tube assembly is fitted on the inner sleeve (34); the rubber tube assembly includes two side rubber tubes (31) at the beginning and end and several middle rubber tubes (33), with spacers (32) between adjacent rubber tube sections; a packer pressure ring (36) is provided below the rubber tube assembly, and the packer pressure ring (36) is fixed to the end of the inner sleeve (34) by a setting pin (37); a suspension body (38) is provided below the inner sleeve (34), and a packer retainer spring (39) is provided on the suspension body (38); a packer retainer is provided outside the suspension body (38). A spring sleeve (40) is provided. The upper end of the packer retaining spring sleeve (40) is connected to the packer pressure ring (36). The packer retaining spring sleeve (40) is provided with a toothed buckle. A lower outer sleeve (43) is provided below the packer retaining spring sleeve (40). A lower central tube (42) of the packer is provided below the upper central tube (27) of the packer. The lower outer sleeve (43) is fitted outside the lower central tube (42) of the packer. A piston (41) is provided in the gap between the packer retaining spring sleeve (40), the upper central tube (27) of the packer, the lower central tube (42) of the packer and the lower outer sleeve (43). Below the packer lower central tube (42) is a cylinder liner (44), and below the cylinder liner (44) is a packer lower connector (45); the packer lower connector (45) is sleeved on the packer lower central tube (42) above, and the lower outer sleeve (43) is connected to the cylinder liner (44); the packer upper central tube (27) is provided with a first through hole at the position between the piston (41) and the packer lower central tube (42), and the packer lower central tube (42) is provided with a second through hole at the position between the cylinder liner (44) and the packer lower connector (45).

3. The injection well pressurized operation process tubing string according to claim 2, characterized in that, The upper central tube (27) is provided with a third through hole at the position between the corresponding upper outer cylinder (26) and the first well washing valve (28); the upper central tube (27) is provided with a well washing channel in the part where the inner sleeve (34) is installed, and the two ends of the inner sleeve (34) are respectively provided with an upper well washing hole and a lower well washing hole; the upper well washing hole and the lower well washing hole are both connected to the well washing channel.

4. The injection well pressurized operation process tubing string according to claim 1, characterized in that, The anti-backflow water distributor (5) includes a main body (49), which has an offset hole and a plug (53) inside the offset hole; the plug (53) has a ceramic ball (54) inside its nozzle, and the diameter of the ceramic ball (54) matches the inner diameter of the plug (53) to form a one-way valve structure; a straightening body (48) is connected above the main body (49), and a water distributor upper connector (46) is provided above the straightening body (48); an upper connecting sleeve (47) is provided outside the straightening body (48), connecting... The upper end of the sleeve (47) is connected to the upper connector (46) of the water distributor, and the lower end is connected to the main body (49); the lower connecting sleeve (50) is connected to the lower part of the main body (49), and the lower connector (51) of the water distributor is connected to the lower part of the lower connecting sleeve (50) by fastening screws (55); the lower connector (51) of the water distributor is provided with a lower guide body (52), and an upper guide sleeve (56) is provided between the upper connector (46) of the water distributor and the straightening body (48), and an upper guide body (57) is provided inside the upper guide sleeve (56).

5. The injection well pressurized operation process tubing string according to claim 1, characterized in that, The multi-functional blowout preventer (6) includes an upper valve body and a lower valve body; the upper valve body includes an upper center tube (68) of the blowout preventer, and the lower valve body includes a lower center tube (75) of the blowout preventer; the lower end of the upper center tube (68) of the blowout preventer is connected to the upper end of the lower center tube (75) of the blowout preventer by a coupling (73); an upper sliding sleeve (62) is provided inside the upper center tube (68) of the blowout preventer and is connected by a first pin (66) of the blowout preventer cylinder; a sealing sleeve (65) is provided outside the upper center tube (68) of the blowout preventer and is connected by a second pin (67) of the blowout preventer cylinder; a toothed sleeve (61) is connected above the sealing sleeve (65), a retaining ring (64) is provided inside the toothed sleeve (61), and a retaining ring seat (63) that cooperates with the retaining ring (64) is provided at the top of the upper center tube (68) of the blowout preventer; Above the dental sleeve (61) is a blowout preventer upper connector (58), and inside the blowout preventer upper connector (58) is a baffle plate (59) with a through hole; the top of the upper sliding sleeve (62) is inserted into the blowout preventer upper connector (58), the top is a downward guide structure, and a blowout preventer steel ball (60) is provided between the upper sliding sleeve (62) and the blowout preventer upper connector (58); below the sealing sleeve (65) is a pressure ring (70), and between the sealing sleeve (65) and the pressure ring (70) is a pressure ring sealing ring (69); the bottom end of the pressure ring (70) is connected to the upper center tube (68) of the blowout preventer; the side of the upper center tube (68) of the blowout preventer is provided with an upper center tube through hole corresponding to the pressure ring (70), and the upper sliding sleeve (62) is provided with an upper sliding sleeve through hole above the upper center tube through hole.

6. The injection well pressurized operation process tubing string according to claim 4, characterized in that, The lower valve body includes a lower center tube (75) of the blowout preventer tailpipe, and a guide tube (77) is fixed outside the lower center tube (75). The two ends of the guide tube (77) are in contact with the lower center tube (75) of the blowout preventer tailpipe, and the middle part has a gap with the lower center tube (75). An upper retaining ring (74) is provided at the upper end of the lower center tube (75), and a lower retaining ring (81) is provided at the lower end. Both the upper retaining ring (74) and the lower retaining ring (81) are provided with axial through holes. Above the lower retaining ring (81) is a... A lower central tube spring (76) is provided between the upper part of the lower sleeve (78) and the upper retaining ring (74); the upper part of the lower sleeve (78) is an upward guide structure, and a lower sleeve steel ball (79) is provided inside; a lower sleeve spring (80) is provided below the lower sleeve steel ball (79); a lower sleeve through hole is provided at the lower end of the side of the lower sleeve (78); the lower central tube (75) of the blowout preventer has an upper connecting hole and a lower connecting hole respectively at the upper and lower ends of the corresponding hole between the side of the lower central tube (75) and the guide tube (77).

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