Water injection well under-pressure operation process pipe column

Abstract

The invention relates to the technical field of oil field water injection well downhole operation, in particular to a water injection well under-pressure operation process pipe column. The water injection well under-pressure operation process pipe column comprises a sleeve, an oil pipe penetrates through the sleeve, a blowout prevention working barrel, a production pipe column and a multifunctional blowout prevention tail pipe are sequentially arranged on the oil pipe from top to bottom, a screen pipe is arranged at the tail end of the oil pipe, and a guide cone is arranged below the screen pipe; a blowout prevention inner plug is arranged in the blowout prevention working barrel; the production pipe column comprises a plurality of matched packers for layering the pipe column, and each layer is provided with an anti-backflow water distributor with a one-way valve structure. The multifunctional blowout prevention tail pipe comprises a lower valve body capable of playing a role in blowout prevention and drainage and an upper valve body with a function of a two-way valve. The functions of water distributor blowout prevention and pipe column bottom blowout prevention and drainage in an oil pipe above a tool section are achieved through the blowout prevention working barrel, the backflow prevention water distributor and the multifunctional blowout prevention tail pipe. The upper valve body and the lower valve body are matched, so that the device has the secondary blowout prevention function, and the blowout prevention and drainage effects are achieved in the tubular column lifting process.

Description

Technical Field

[0001] The invention relates to the technical field of downhole operation of water injection wells in oil fields, and in particular to a process pipe string for pressure-operated water injection wells. Background Art

[0002] In the prior art, the oil field generally adopts the method of throwing plugs in the tubing, throwing dead water nozzles on the water distributor and installing a two-way valve on the tail pipe when using the pressure operation pipe string. This method controls the high pressure and overflow in the tubing through the tubing plug and the two-way valve during the pipe lifting process, and controls the overflow in the pipe into the center pipe through the two-way valve and the dead water nozzle on the water distributor at the bottom of the tubing during the lowering process. However, the following problems still exist: the tubing plug must be lowered before the pressure operation, and can only seal the tubing above the tool section; the lowering position of the sealing tool is uncertain and the locking Poor stability, easy to fly out under high pressure, so the pressure must be released when lifting to the tool, and it is impossible to carry pressure throughout the process; the method of throwing a plug with a dead mouth into the water distributor before the operation is difficult to throw and the success rate is not high for wells with scaling in the tubing; in order to solve the problem of blowout prevention in the tubing above the tool end, the method of throwing an oil pipe plug into the tubing before the operation is adopted, but it is difficult to plug for high-pressure wells and the success rate is not high; after adopting the above blowout prevention measures, during the process of lifting and lowering the tubing, the tubing is prone to upward push and tubing leakage due to the pressure from the bottom. Summary of the invention

[0003] 1. Technical issues to be resolved In view of the deficiencies in the prior art, the present invention provides a process string for pressurized operation of water injection wells, which solves the problems in the prior art that the pressure must be released when raising the tool and that it is impossible to operate under pressure throughout the entire process; it is difficult to fish out wells with scale in the string and the success rate is low; it is difficult to plug high-pressure wells and the success rate is low; and during the process of raising and lowering the string, the string is prone to upward pushing and string leakage due to the pressure from the bottom.

[0004] (II) Technical solution In order to solve the above problems, the present invention provides a process string for water injection well pressure operation, comprising: a casing, an oil pipe is passed through the casing, a blowout preventer working barrel, a production pipe string, and a multifunctional blowout preventer tail pipe are arranged in sequence below the oil pipe, a screen pipe is arranged at the end of the oil pipe, and a guide cone is arranged below the screen pipe; a blowout preventer inner plug is arranged in the blowout preventer working barrel, and the blowout preventer inner plug and the blowout preventer working barrel cooperate to open the oil-casing channel; the production pipe string comprises a plurality of matching packers with an anti-mid-sealing design to separate the production pipe string into several layers, and each layer is provided with an anti-backflow water distributor with a one-way valve function; the multifunctional blowout preventer tail pipe comprises a lower valve body that plays a role of blowout prevention and leakage and an upper valve body with a two-way valve function.

[0005] Preferably, the blowout prevention working cylinder includes a sleeve, a sleeve retaining spring seat is provided above the sleeve; the sleeve is connected to the sleeve retaining spring seat and then inserted into the outer sleeve; a sleeve upper joint is provided above the sleeve retaining spring seat, and the sleeve upper joint is inserted into the outer sleeve; the upper end of the outer sleeve is threadedly connected to the sleeve upper joint, and the lower end is threadedly connected to the sleeve lower joint; the sleeve and the outer sleeve are fixed by a sleeve pin; a cavity is provided between the lower end of the sleeve in the outer sleeve and the upper end of the sleeve lower joint; the diameter of the middle part of the sleeve is smaller than the diameter at both ends to form a groove; the inner diameter of the part of the cavity inside the outer sleeve is larger than the maximum diameter of the sleeve; a sleeve retaining spring is provided on the outside of the top end of the sleeve; a horse tooth buckle is provided inside the outer sleeve, and a jacket liquid outlet is provided at the corresponding part between the outer sleeve and the sleeve groove.

[0006] Preferably, the blowout-proof inner plugging comprises an expanding sleeve, a blowout-proof inner plugging sealing sleeve is connected to the bottom of the expanding sleeve, an inner plugging connecting sleeve is connected to the bottom of the blowout-proof inner plugging sealing sleeve, and a conical head is connected to the bottom of the inner plugging connecting sleeve; a spring claw is provided on the top of the expanding sleeve; an axial guide groove is provided inside the inner plugging connecting sleeve, a blowout-proof valve assembly is provided on the guide groove, and the top of the blowout-proof valve assembly is an upward cone; the bottom of the blowout-proof inner plugging sealing sleeve is a conical surface with a small top and a large bottom, and cooperates with the top of the blowout-proof valve assembly; a movable ball seat is fixed in the inner plugging connecting sleeve by a ball seat pin; an axial through hole is provided in the middle of the movable ball seat, and the upper end of the through hole is a guide surface with a large top and a small bottom; an inner plugging steel ball is provided above the movable ball seat, and the diameter is matched with the guide surface of the upper end of the movable ball seat; the inner plugging connecting sleeve is circumferentially provided with an inner plugging liquid outlet hole corresponding to the part below the movable ball seat; and a plurality of blowout-proof inner plugging sealing rings are provided on the blowout-proof inner plugging sealing sleeve.

[0007] Preferably, the matching packer comprises a center tube on the packer, the upper end of the center tube on the packer is connected to the upper joint of the packer, and an upper outer tube is arranged outside the upper joint of the packer; a first well-washing valve that can move up and down is arranged between the upper outer tube and the center tube on the packer, and the lower end of the first well-washing valve is connected to the second well-washing valve; an inner casing is arranged outside the center tube on the packer, and the inner casing is located below the second well-washing valve, and a rubber tube group is sleeved on the inner casing; the rubber tube group comprises two side rubber tubes at the head and the tail and a plurality of middle rubber tubes, and a spacer is arranged between two adjacent sections of rubber tubes; a packer pressure ring is arranged below the rubber tube group, and the packer pressure ring is fixed to the end of the inner casing by a sealing pin; a suspension body is arranged below the inner casing, and a packer retaining spring is arranged on the suspension body; A packer retaining spring sleeve is provided, the upper end of which is connected to a packer pressure ring, and a horse tooth buckle is provided inside the packer retaining spring sleeve; a lower outer sleeve is provided below the packer retaining spring sleeve, a lower center tube of the packer is provided below the upper center tube of the packer, the lower outer sleeve is sleeved outside the lower center tube of the packer, and a piston is provided in the gap between the packer retaining spring sleeve, the upper center tube of the packer, the lower center tube of the packer and the lower outer sleeve; a cylinder sleeve is provided below the lower center tube of the packer, and a lower joint of the packer is provided below the cylinder sleeve; the upper part of the lower joint of the packer is sleeved on the lower center tube of the packer, and the lower outer sleeve is connected to the cylinder sleeve; a first through hole is provided at a position between the upper center tube of the packer corresponding to the piston and the lower center tube of the packer, and a second through hole is provided at a position between the lower center tube of the packer corresponding to the cylinder sleeve and the lower joint of the packer.

[0008] Preferably, the upper center tube is provided with a third through hole at a position corresponding to the upper outer tube and the first well washing valve; the inner sleeve installation part of the upper center tube is provided with a well washing channel, and the two ends of the inner sleeve 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.

[0009] Preferably, the anti-backflow water distributor includes a main body, a side hole is provided in the main body, and a plug is provided in the side hole; a ceramic ball is provided in the water nozzle of the plug, and the diameter of the ceramic ball matches the inner diameter of the plug to form a one-way valve structure; a straightening body is connected to the top of the main body, and an upper joint of the water distributor is provided above the straightening body; an upper connecting sleeve is provided outside the straightening body, and the upper end of the connecting sleeve is connected to the upper joint of the water distributor, and the lower end is connected to the main body; a lower connecting sleeve is connected to the bottom of the main body, and the bottom of the lower connecting sleeve is connected to the lower joint of the water distributor by a fastening screw; a lower guide body is provided in the lower joint of the water distributor, an upper guide sleeve is provided between the upper joint of the water distributor and the straightening body, and an upper guide body is provided in the upper guide sleeve.

[0010] Preferably, the multifunctional blowout-preventing tail pipe comprises an upper valve body and a lower valve body; the upper valve body comprises an upper center pipe of the blowout-preventing tail pipe, and the lower valve body comprises a lower center pipe of the blowout-preventing tail pipe; the lower end of the upper center pipe of the blowout-preventing tail pipe is connected to the upper end of the lower center pipe of the blowout-preventing tail pipe by a coupling; an upper sliding sleeve is provided inside the upper center pipe of the blowout-preventing tail pipe and is connected through a first pin of the blowout-preventing tube; a sealing sleeve is provided outside the upper center pipe of the blowout-preventing tail pipe and is connected through a second pin of the blowout-preventing tube; a dental sleeve is connected above the sealing sleeve, a clamping ring is provided inside the dental sleeve, and a clamping ring matching the clamping ring is provided at the top of the upper center pipe of the blowout-preventing tail pipe Seat; an upper joint of the blowout-proof tail pipe is provided above the tooth sleeve, and a ball baffle with a through hole is provided in the upper joint of the blowout-proof tail pipe; the top of the upper sliding sleeve is inserted into the upper joint of the blowout-proof tail pipe, and the top is a downward guiding structure, and a blowout-proof tail pipe steel ball is provided between the upper sliding sleeve and the upper joint of the blowout-proof tail pipe; 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 pipe of the blowout-proof tail pipe; an upper center pipe through hole is provided on the side of the upper center pipe of the blowout-proof tail pipe corresponding to the bottom of the pressure ring, and an upper sliding sleeve through hole is provided on the upper sliding sleeve corresponding to the upper center pipe through hole.

[0011] Preferably, the lower valve body comprises a lower center tube of the blowout-proof tail pipe, a guide tube is fixed outside the lower center tube of the blowout-proof tail pipe, two ends of the guide tube are in contact with the lower center tube of the blowout-proof tail pipe, and a gap is provided between the middle part and the lower center tube of the blowout-proof tail pipe; an upper retaining ring is provided at the upper end of the lower center tube of the blowout-proof tail pipe, and a lower retaining ring is provided at the lower end, and axial through holes are provided on the upper retaining ring and the lower retaining ring; a lower sliding sleeve is provided above the lower retaining ring, and a lower center tube spring is provided between the upper part of the lower sliding sleeve and the upper retaining ring; an upward guiding 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 surface of the lower sliding sleeve; the side surface of the lower center tube of the blowout-proof tail pipe corresponds to the gap part between the guide tube, and an upper connecting hole and a lower connecting hole are provided at the upper and lower ends respectively.

[0012] (III) Beneficial effects The process pipe string for pressurized operation of water injection wells provided by the present invention realizes blowout prevention again before lifting the pipe string by providing a secondary blowout prevention structure on the multifunctional blowout prevention tail pipe, thereby enhancing the overall safety of pressurized operation during construction and eliminating the need for pressure relief operation; the blowout prevention working tube and the blowout prevention inner plug cooperate to realize the plugging function of the liquid in the pipe string at the lower end of the tool section; the production pipe string is layered by a plurality of matching packers, and the water injection well is pressurized at the wellhead after the pipe string is lowered in cooperation with the check valve structure in the blowout prevention tail pipe; the check valve structure is provided in the plug of the anti-backflow water distributor to ensure that the device can realize discharge balance pressure without jetting overflow; the anti-mid-seat sealing design in the matching packer enables the water pipe string to be smoothly lowered into the expected position. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1It is a schematic diagram of the structure of the process string for water injection well pressure operation according to the present invention; Figure 2 This is a structural diagram of a blowout prevention mandrel of a water injection well pressure operation process string of the present invention; Figure 3 This is a blowout prevention internal plugging structure diagram of a water injection well pressure operation process pipe string of the present invention; Figure 4 This is a structural diagram of a matching packer for a water injection well pressure operation process string of the present invention; Figure 5 This is a structural diagram of a backflow prevention water distributor for a pressure-operated process pipe string for a water injection well according to the present invention; Figure 6 This is a structural diagram of a plugging device for a water injection well pressure operation process pipe string of the present invention; Figure 7 The invention discloses a multifunctional blowout-preventing tail pipe structure of a water injection well pressure operation process string.

[0014] Among them, 1. casing; 2. tubing; 3. blowout prevention working tube; 4. matching packer; 5. anti-backflow water distributor; 6. multi-functional blowout prevention tail pipe; 7. screen pipe; 8. guide cone; 9. upper joint of sliding sleeve; 10. outer sleeve; 11. sliding sleeve retaining spring; 12. sliding sleeve retaining spring seat; 13. sliding sleeve; 14. fixing pin; 15. lower joint of sliding sleeve; 16. expansion sleeve; 17. blowout prevention inner plugging sealing sleeve; 18. Blowout preventer assembly; 19, blowout preventer sealing ring; 20, inner plugging steel ball; 21, movable ball seat; 22, ball seat pin; 23; inner plugging connecting sleeve; 24; conical head; 25, upper joint of packer; 26, upper outer tube; 27, upper center tube of packer; 28, first well washing valve; 29, second well washing valve; 30, sealing seat; 31, side rubber tube; 32, spacer; 33, middle rubber tube; 34, inner casing; 35, unsealing pin; 36, packer pressure ring; 37, setting pin; 38, hanging body; 39, packer retaining spring; 40, packer retaining spring sleeve; 41, piston; 42, lower center tube of packer; 43, lower outer sleeve; 44, cylinder sleeve; 45, lower joint of packer; 46, upper joint of water distributor; 47, upper connecting sleeve; 48, straightening body; 49, main body; 50. Lower connecting sleeve; 51. Lower joint 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 joint of blowout tail pipe; 59. Ball baffle; 60. Steel ball of blowout tail pipe; 61. Tooth 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 pipe of blowout preventer; 69. Compression ring sealing ring; 70. Compression ring; 71. Circlip; 72. Guide head; 73. Coupling; 74. Upper retaining ring; 75. Lower center pipe of blowout preventer; 76. Lower center pipe spring; 77. Guide pipe; 78. Lower sleeve; 79. Steel ball of lower sleeve; 80. Lower sleeve spring; 81. Lower retaining ring. Implementation

[0015] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0016] In the description of the present invention, it is necessary to understand that the orientations or positional relationships indicated by “upper”, “lower”, “inside”, “outside”, “top”, “bottom”, etc. are all based on the orientations or positional relationships shown in the accompanying drawings. The purpose is only to facilitate the description of the present invention and simplify the description. It does not indicate or imply that the referred parts must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0017] like Figure 1-6 As shown, the present invention provides a process string for water injection well pressure operation, specifically comprising: a casing 1 and an oil pipe 2, wherein the oil pipe 2 is inserted into the casing 1, and a blowout prevention working barrel 3, a production pipe string and a multifunctional blowout prevention tail pipe 6 are sequentially arranged on the oil pipe 2 from top to bottom, a screen pipe 7 is arranged at the end of the oil pipe 2, and a guide cone 8 is arranged below the screen pipe 7.

[0018] The production string includes a plurality of matching packers 4 to separate the production string into several layers. Each layer of the production string is provided with an anti-backflow water distributor 5 to perform layered water injection and blowout prevention treatment on the production string to improve the blowout prevention capability of the device. The blowout prevention working cylinder 3 is provided with a blowout prevention internal plug.

[0019] It should be noted that the anti-backflow water distributor 5 is provided with a plug 53, and the plug 53 is provided with a check valve structure, which can inject liquid into the production tubing. When the liquid moves in the reverse direction, the check valve structure can prevent the flow of the liquid to achieve the anti-blowout function.

[0020] like Figure 2 As shown, the blowout prevention working cylinder 3 includes a sleeve 13, the upper end of the sleeve 13 is threadedly connected to the sleeve retaining spring seat 12 to cooperate with the blowout prevention inner plug, and the sleeve 13 is inserted into the outer sleeve 10 after being connected with the sleeve retaining spring seat 12. A sleeve upper joint 9 is provided above the sleeve retaining spring seat 12 to connect the oil pipe 2; the sleeve 13 is connected to the outer sleeve 10 through a fixing pin 14. When the downward force applied to the sleeve 13 exceeds the stress limit of the fixing pin 14, the fixing pin 14 is cut off and the sleeve 13 moves downward; a sleeve lower joint 15 is provided below the sleeve 13 to connect with the components below.

[0021] Among them, the diameter of the side of the sleeve 13 is smaller than the diameter of the two ends, and a groove is formed on the side of the sleeve 13; the lower end of the outer sleeve 10 is connected to the sleeve lower joint 15, and a cavity is provided between the sleeve lower joint 15 and the sleeve 13 in the outer sleeve 10, and the diameter of the cavity is larger than the sleeve diameter. When the sleeve 13 moves downward, part of the groove enters the cavity with the sleeve 13 moving downward; the side of the outer sleeve 10 is provided with an outer sleeve liquid outlet hole, and when the groove enters the cavity, the outer sleeve liquid outlet hole coincides with part of the groove, and at the same time, the bottom of the sleeve 13 still does not contact the sleeve lower joint 15, at this time, the inside of the blowout preventer working cylinder 3 is connected with the oil casing annulus to establish a liquid flow channel.

[0022] It should be noted that a sleeve retaining spring 11 is provided at the top of the sleeve 13, and a tooth-shaped buckle is provided inside the outer sleeve 10. When the sleeve 13 moves downward, the sleeve retaining spring 11 cooperates with the tooth-shaped buckle to fix the sleeve 13. At this time, there is still a distance between the bottom of the sleeve 13 and the top of the sleeve upper joint 15, thereby ensuring the stability and normal operation of the liquid flow channel.

[0023] In the present invention, a blowout-proof inner plug is provided in the blowout-proof working cylinder 3, and the blowout-proof inner plug includes an expansion sleeve 16, and a spring claw is provided at the top of the expansion sleeve 16, and the spring claw cooperates with the sliding sleeve retaining spring seat 12 to fix the blowout-proof inner plug; the expansion sleeve 16 is connected to the blowout-proof inner plug sealing sleeve 17 below, and a plurality of blowout-proof inner plug sealing rings 19 are provided outside the blowout-proof inner plug sealing sleeve 17 to ensure the sealing performance of the device; the blowout-proof inner plug sealing sleeve 17 is connected to the inner plug connecting sleeve 23 below, and a blowout-proof valve assembly 18 is provided at the top of the inner plug connecting sleeve 23, and the upper end of the blowout-proof valve assembly is an upward cone, and the lower end surface of the blowout-proof inner plug sealing sleeve 17 cooperates with the top of the blowout-proof valve assembly 18 to form a single-flow valve structure, when the liquid flows from top to bottom, it can flow freely, and when the liquid moves from bottom to top, the blowout-proof valve assembly 18 moves upward and cooperates with the inner plug connecting sleeve 23 to prevent the liquid from flowing upward. A movable ball seat 21 is fixed in the inner blocking connecting sleeve 23 by a ball seat pin 22, and an inner blocking steel ball 20 is provided on the movable ball seat 21. The upper surface of the movable ball seat 21 cooperates with the inner blocking steel ball 21 to form a one-flow valve structure. When the liquid flows from top to bottom, the inner blocking steel ball 21 prevents the flow of liquid.

[0024] Among them, an inner plugging liquid outlet hole is provided on the inner plugging connecting sleeve 23 below the movable ball seat 21. After the liquid flow channel is established in the blowout prevention working cylinder 3, the pressurization continues. When the liquid pressure on the inner plugging 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 plugging liquid outlet hole on the inner plugging connecting sleeve 23 is connected with the inside of the blowout prevention inner plug to form a liquid channel. When the tubing string is lifted afterwards, the liquid in the oil tubing string enters the oil casing annulus through the blowout prevention inner plug and the blowout prevention working cylinder 3, forming an anti-blocking and anti-splashing structure.

[0025] It should be noted that the blowout preventer inner plug and the blowout preventer working barrel 3 are designed as a separate body. At the beginning of the work, the blowout preventer inner plug is not installed on the blowout preventer working barrel 3. Before the pipe string is to be operated, the valve at the wellhead is opened to drop the blowout preventer inner plug. Under the push of the water injection pressure, the blowout preventer inner plug moves downward, contacts the blowout preventer working barrel 3 and works.

[0026] like Figure 4As shown, the matching packer 4 includes a packer upper center pipe 27, the upper end of which is connected to the packer upper joint 25 for connecting with the upper component; an upper outer tube 26 is provided outside the packer upper joint 25; a first well-washing valve 28 that can move up and down is provided between the upper outer tube 26 and the packer upper center pipe 27, the lower end of the first well-washing valve 28 is connected to the second well-washing valve 29, and the packer upper center pipe 27 is provided with a connecting hole at a position corresponding to the position between the first well-washing valve 28 and the packer upper joint 25, and liquid enters the first well-washing valve through the connecting hole. The well is cleaned by the valve 28 and the second well-washing valve 29; an inner casing 34 is provided outside the central tube 27 of the packer, and the inner casing 34 is located below the second well-washing valve 29 and is used to install a rubber tube group; a rubber tube group is sleeved on the inner casing 34, and the rubber tube group includes two side rubber tubes 31 at the head and the tail and a plurality of middle rubber tubes 33, and a spacer 32 is provided between two adjacent sections of the rubber tube to prevent the rubber tubes from being squeezed and collided with each other and causing damage to the rubber tubes; a packer pressure ring 36 is provided below the rubber tube group, and the packer pressure ring 36 is fixed at the end of the inner casing 34 by a sealing pin 37; the inner casing A suspension body 38 is provided below the tube 34, and a packer retaining spring 39 is provided on the suspension body 38. The suspension body 38 is connected to the inner casing 34 through an unsealing pin 35; a packer retaining spring sleeve 40 is provided outside the suspension body 38, and the upper end of the packer retaining spring sleeve 40 is connected to the packer pressure ring 36, and a horse tooth buckle is provided inside the packer retaining spring sleeve 40. A packer retaining spring 39 is provided on the suspension body 38; a lower outer sleeve 43 is provided below the packer retaining spring sleeve 40, and a packer lower center pipe 42 is provided below the packer upper center pipe 27, and the lower outer sleeve 43 is sleeved outside the packer lower center pipe 42, and the lower outer sleeve 43 is sleeved on the packer retaining spring sleeve 40. A piston 41 is provided in the gap between the upper center tube 27 of the packer, the lower center tube 42 of the packer and the lower outer sleeve 43; a cylinder sleeve 44 is provided below the lower center tube 42 of the packer, and a lower joint 45 of the packer is provided below the cylinder sleeve 44; the upper part of the lower joint 45 of the packer is sleeved on the lower center tube 42 of the packer, and the lower outer sleeve 43 is connected to the cylinder sleeve 44; a first through hole is provided on the upper center tube 27 of the packer corresponding to the position between the piston 41 and the lower center tube 42 of the packer, and a second through hole is provided on the lower center tube 42 of the packer corresponding to the position between the cylinder sleeve 44 and the lower joint 45 of the packer.

[0027] When the device is pressurized, high-pressure liquid enters the annulus between the upper center pipe 27 of the packer, the lower center pipe 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 spring sleeve 40 and the packer pressure ring 36 upward; at the same time, the high-pressure liquid enters the annulus between the lower center pipe 42 of the packer, the cylinder sleeve 44 and the lower joint 45 of the packer through the second through hole to push the cylinder sleeve 44, the lower outer sleeve 43, and the packer retaining spring sleeve 40, thereby pushing the packer pressure ring 36 upward. When the thrust of the packer pressure ring 36 is greater than the maximum stress limit of the unsealing pin 35, the unsealing pin 35 is cut off, and the packer pressure ring 36 moves upward to squeeze the rubber cylinder group for setting. At this time, the packer retaining spring sleeve 40 moves upward, and when the horse tooth buckle in the packer retaining spring sleeve 40 engages with the packer retaining spring 39, the state of the packer retaining spring sleeve 40 and the rubber cylinder group is fixed, and the device is set.

[0028] Among them, the sealing pin 37 plays a role in preventing mid-sealing during the working process. Only when the pressure is greater than its maximum shear stress, the sealing pin 37 is cut off, and the rubber cylinder group can perform normal sealing work, ensuring that mid-sealing will not occur during the lowering of the device, and ensuring that the device can be smoothly lowered to the sealing position.

[0029] It should be noted that the upper central tube 27 is provided with a third through hole at a position corresponding to the upper outer tube 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 upper well washing hole and the lower well washing hole are respectively provided at both ends of the inner sleeve 34; the upper well washing hole and the lower well washing hole are both connected to the well washing channel.

[0030] like Figure 5 As shown, the anti-backflow water distributor 5 includes a main body 49, the upper part of the main body 49 is connected to a straightening body 48, and the upper end of the straightening body 48 is connected to an upper guide sleeve 56; an upper guide body 57 is arranged inside the upper guide sleeve 56, and the upper end of the upper guide sleeve 56 is connected to the upper joint 46 of the water distributor; an upper connecting sleeve 47 is arranged outside the straightening body 48, and the upper end of the upper connecting sleeve 47 is connected to the upper joint 46 of the water distributor, and the lower end is connected to the main body 49; a lower connecting sleeve 50 is arranged at the lower end of the main body 49, and a lower joint 51 of the water distributor is arranged at the lower end of the lower connecting sleeve 50, and the lower joint 51 of the water distributor is connected to the lower connecting sleeve 50 by a fastening screw 55; a lower guide body 52 is arranged inside the lower joint 51 of the water distributor; a side hole is arranged inside the main body 49, and a plugging device 53 is placed inside the side hole; a ceramic ball 54 is arranged inside the water nozzle of the plugging device 53.

[0031] The ceramic ball 54 is matched with the inner surface of the water inlet of the plug 53. When the device injects water through the plug 53, the liquid enters the surrounding annulus through the water nozzle of the plug 53; at the same time, when the liquid in the annulus flows back, the ceramic ball 54 is pushed by the liquid to block the water inlet of the plug 53, preventing the liquid from flowing back and forming a check valve structure. The above structure enables the anti-backflow water distributor 5 to both inject water normally and prevent liquid from flowing back to play a role in preventing spraying.

[0032] like Figure 6 As shown, the multifunctional blowout-preventing tail pipe 6 comprises a blowout-preventing tail pipe upper center pipe 68 and a blowout-preventing tail pipe lower center pipe 75; an upper sliding sleeve 62 is connected to the blowout-preventing tail pipe upper center pipe 68 through a first blowout-preventing tube pin 66, the upper end of the upper sliding sleeve 62 is a downward guiding structure, and a matching blowout-preventing tail pipe steel ball 60 is provided at the upper end of the upper sliding sleeve 62; a sealing sleeve 65 is provided outside the blowout-preventing tail pipe upper center pipe 68 and is connected through a second blowout-preventing tube pin 67; the upper end of the upper sliding sleeve 62 is connected to the blowout-preventing tail pipe upper joint 58, and the blowout-preventing tail pipe A ball baffle 59 with a through hole is provided in the upper joint 58, and a gap is directly left between the ball baffle 59 and the blowout tail pipe steel ball 60 to ensure that the blowout tail pipe steel ball 60 can move freely and prevent the blowout tail pipe steel ball 60 from flowing out of the multifunctional blowout tail pipe 6 along with the liquid; the upper end of the sealing sleeve 65 is connected to the socket 61, and the upper end of the socket 61 is connected to the upper joint 58 of the blowout tail pipe; a pressure ring 70 is provided on the center pipe 68 of the blowout tail pipe, and the pressure ring 70 is below the sealing sleeve 65, and a pressure ring sealing ring 69 is provided between the sealing sleeve 65 and the sealing sleeve 65.

[0033] The upper sleeve 62 and the blowout tail pipe upper center pipe 68 are respectively provided with annularly arranged upper sleeve through holes and upper center pipe through holes. The upper center pipe through hole of the blowout tail pipe upper center pipe 68 is located below the pressure ring 70, and the upper sleeve through hole of the upper sleeve 62 is located above the upper center pipe through hole of the blowout tail pipe upper center pipe 68. When the pipe string is lowered to the predetermined position, the oil pipe is pressurized, and the high-pressure liquid pushes the blowout tail pipe steel ball 60 to drive the upper sleeve 62 downward. When the pressure is greater than the maximum stress limit of the first pin 66 of the blowout preventer, the first pin 66 of the blowout preventer is cut off, and the upper sleeve 62 slides to the upper end face of the blowout tail pipe upper center pipe 68. At this time, the upper sleeve through hole is radially opposite to the upper center pipe through hole, and the interior of the multifunctional blowout preventer 6 is connected with the oil casing annulus to establish a liquid channel to meet the well washing needs during production.

[0034] During the well washing operation, when the matching packer 4 is sealed, high-pressure liquid flows out from the third through hole, pushing the first well washing valve 28 and the second well washing valve 29 to move downward to block the upper well washing hole of the inner sleeve 34, preventing the liquid in the well from entering from the lower well washing hole and flowing out of the wellhead through the well washing channel; when the matching packer 4 is sealed and the well washing operation is carried out, high-pressure well washing liquid is injected into the surrounding annulus, at which time the second well washing valve 29 is squeezed upward, and due to the pressure difference, the first well washing valve 28 and the second well washing valve 29 move upward, at which time the upper well washing hole is opened, and the well washing liquid enters the upper well washing hole and flows out from the lower well washing hole through the well washing channel, and then the liquid in the annulus enters the pipe string from the liquid channel of the multifunctional blowout preventer tail pipe 6 and flows out from the top of the pipe string to achieve the well washing effect.

[0035] It should be noted that a guide head 72 is provided at the bottom end of the upper sleeve 62, and a retaining spring 71 is provided above the guide head 72. When the upper sleeve 62 descends, the retaining spring 71 slides out of the upper center tube 68 of the blowout preventer tail pipe and pops out and is stuck at the bottom end of the upper center tube 68 of the blowout preventer tail pipe, fixing the upper sleeve 62 and ensuring the stability of the liquid channel of the multifunctional blowout preventer tail pipe 6.

[0036] In the present invention, the lower center pipe 75 of the blowout preventer tail pipe is butted against the upper center pipe 68 of the blowout preventer tail pipe and connected at the butt joint by a coupling 73; a flow guide pipe 77 is provided outside the lower center pipe 75 of the blowout preventer tail pipe, and the inner diameter of the middle part of the flow guide pipe 77 is larger than that of the lower center pipe 75 of the blowout preventer tail pipe, and a gap is formed between the flow guide pipe 77 and the lower center pipe 75 of the blowout preventer tail pipe; an upper connecting hole and a lower connecting hole are respectively provided at the upper and lower ends of the lower center pipe 75 of the blowout preventer tail pipe corresponding to the gap between the flow guide pipe 77; the blowout preventer tail pipe 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; a lower sliding sleeve 78 which can move in the up and down directions is provided inside the lower center tube 75 of the blowout-proof tail pipe, and a lower sliding sleeve flow hole corresponding to the position of the lower flow hole is provided on the side wall of the lower sliding sleeve 78; the upper end of the lower sliding sleeve 78 is an upward guiding structure, and a lower sliding sleeve steel ball 79 is provided inside the lower sliding sleeve 78; a lower center tube spring 76 is provided between the lower sliding sleeve 78 and the upper retaining ring 74, and a lower sliding sleeve spring 80 is provided between the lower sliding sleeve steel ball 79 and the lower retaining ring 81.

[0037] In the process of assembling and lowering the device, the liquid enters the lower center tube 75 of the blowout-proof tail pipe from below, enters the lower sleeve 78 through the lower retaining ring 81, pushes the lower sleeve steel ball 79 to move upward to block the upper port of the lower sleeve 78, and prevents the liquid from directly rushing into the center and causing splashing. At the same time, when the pressure of the lower liquid is large, the liquid pushes the lower sleeve steel ball 79 and the lower sleeve 78 to move upward to squeeze the lower center tube spring 76. During the upward movement, the lower sleeve flow hole coincides with the lower connecting hole of the lower center tube 75 of the blowout-proof tail pipe. At this time, the liquid enters the gap between the guide pipe 77 and the lower center tube 75 of the blowout-proof tail pipe through the lower flow hole, and then enters the upper part of the lower sleeve 78 in the lower center tube 75 of the blowout-proof tail pipe through the upper connecting hole. At this time, the gravity of the liquid above the lower sleeve 78 is used to balance the upward pressure of the lower liquid and appropriately reduce the pressure of the lower liquid, so as to ensure the blowout-proof performance and stability of the device. At the same time, by diverting part of the lower liquid to the lower center tube 75 of the blowout-proof tail pipe, the function of preventing the pipe from collide can be achieved. When the lower liquid pressure continues to increase, the lower sleeve 78 continues to move upward, and the lower sleeve flow hole is separated from the lower connecting hole. At this time, the liquid no longer enters the lower center pipe 75 of the blowout preventer tail pipe, thereby realizing the re-discharge and blowout prevention function at the bottom of the pipe string.

[0038] In the present invention, a screen tube 7 is provided at the bottom of the pipe column to filter out large debris in the liquid below to prevent blockage and jamming inside the pipe column; a guide cone 8 is provided below the screen tube 7 to assist the lowering of the pipe column, reduce the resistance to the lowering of the pipe column, and improve the working efficiency of the device.

[0039] It should be noted that the contacting parts between the components in the present invention are provided with a plurality of sealing rings to ensure the sealing of the device during use, ensure the normal operation of the device, and improve the practicality of the device.

[0040] The process string for pressurized operation of water injection wells provided by the present invention realizes the secondary blowout prevention before the string is lifted, enhances the overall safety of pressurized operation during the construction process, and does not need to perform pressure relief operation; realizes the three-stage blowout prevention of the tool section, the upper part of the tool section and the lower part of the tool section; the production string is layered by multiple matching packers and the check valve structure in the blowout prevention tail pipe is used to realize the restoration of normal production of the water injection well by wellhead pressure after the string is lowered; the check valve structure is provided in the plug of the anti-backflow water distributor to ensure that the device can realize the discharge balance pressure without spraying overflow; the anti-midway setting design in the matching packer is used to realize the smooth lowering of the water pipe string into the expected position. The specific operation process of the device is as follows: Step 1: Connect the oil pipe and various components of the device from bottom to top, and connect the screen pipe and guide cone to the end of the lowest oil pipe.

[0041] Step 2: Lower the assembled tubing string into the well. During the tubing string lowering process, the multifunctional blowout preventer tail pipe is initially in a sealed state. As it is lowered into the wellbore, the pressure in the wellbore gradually increases, and the pressure of the well fluid below gradually increases; the well fluid enters the tubing string through the screen pipe and moves upward into the sliding sleeve, pushing the sliding sleeve steel ball and the sliding sleeve to move upward, compressing the lower center pipe spring, and when the through hole of the sliding sleeve gradually coincides with the lower flow hole of the lower center pipe of the blowout preventer tail pipe, a small amount of well fluid enters the gap between the lower center pipe of the blowout preventer tail pipe and the guide pipe through the lower flow hole, and then passes through the upper through hole of the lower center pipe of the blowout preventer tail pipe When the flow hole flows into the blowout preventer tail pipe, the well pressure continues to increase. When the through hole of the lower sleeve and the lower flow hole of the lower center pipe of the blowout preventer tail pipe completely coincide with each other, the well fluid flow rate flowing into the multifunctional blowout preventer tail pipe is the largest. When the downhole pressure continues to increase, the lower sleeve continues to move upward, the through hole of the lower sleeve and the lower flow hole are staggered, and the liquid no longer enters the multifunctional blowout preventer tail pipe, ensuring that the liquid level in the oil pipe is always lower than the liquid level in the oil casing annulus, achieving the effect of blowout prevention. At the same time, the gravity of the liquid entering the pipe string can properly balance the upward force applied to the pipe string when it is lowered into the well, thereby achieving the effect of preventing pipe channeling.

[0042] Step 3: When the tubing string is lowered to the predetermined position, the oil pipe is pressurized. At this time, the high-pressure liquid pushes the blowout preventer tail pipe steel ball and the upper sliding sleeve downward, cutting off the first pin of the blowout preventer. The upper sliding sleeve is radially connected to the flow space of the center pipe on the blowout preventer tail pipe. The tubing string is connected to the annulus of the oil casing through the functional blowout preventer tail pipe, providing conditions for well washing during production. The blowout preventer tail pipe steel ball seats downward on the upper sliding sleeve, and the bottom of the multifunctional blowout preventer tail pipe is sealed. As the pressure in the oil pipe increases, the high-pressure liquid enters the upper center pipe of the packer and the lower center pipe of the packer through the first through hole of the upper center pipe of the packer. , the annulus between the piston and the lower outer sleeve, and at the same time, through the second through hole of the upper center pipe of the packer, enter the annulus between the lower center pipe of the packer, the cylinder sleeve and the lower joint of the packer, respectively push the piston and cylinder sleeve, the lower outer sleeve, the cylinder sleeve, and then push the retaining ring sleeve and the packer pressure ring upward, cut the sealing pin and push the rubber cylinder group to compress, and at the same time, the suspension body moves downward together, the packer moves downward and cooperates with the retaining ring sleeve of the packer to fix the packer, and the packer is sealed. At the same time, the liquid flows out from the third through hole and pushes the first well washing valve and the second well washing valve downward to block the upper well washing hole and seal the well washing channel. During backwashing, the annulus is pressurized, and the high-pressure liquid enters through the flow holes of the upper center pipe and the upper sliding sleeve of the blowout preventer tail pipe, pushes the steel ball of the blowout preventer tail pipe upward, enters the pipe string and goes out of the wellhead.

[0043] Step 4: Perform well washing work. Add high-pressure well washing liquid into the annulus of the tubing. At this time, the high-pressure well washing liquid pushes the second well washing valve upward, the first well washing valve and the second well washing valve move upward, the upper well washing hole opens, and the well washing liquid enters the well washing channel through the upper well washing hole and flows out from the lower well washing hole. At this time, the liquid in the annulus is squeezed by the well washing liquid and enters the tubing through the liquid channel of the multi-functional blowout preventer tail pipe and moves upward, and is finally discharged from the wellhead to form a passage, thereby achieving the well washing effect.

[0044] The cam is then pushed back into place and the cam is released, and the cam is released again ...

[0045] Step 6. After the work is completed, the tubing is lifted and the tubing is lifted to unseal the packer. At this time, the upper joint of the packer moves upward to drive the rubber tube upward, thereby restoring the rubber tube to its original position and unsealing the packer. Then, the artificial well bottom is explored deeper. After the tubing hits the well bottom, the lower center pipe of the blowout preventer tail pipe drives the coupling, the retaining ring seat, and the retaining ring upward, and the second pin of the blowout preventer is cut off. The upper center pipe of the blowout preventer tail pipe moves upward. At this time, the flow space of the upper center pipe of the blowout preventer tail pipe and the upper sliding sleeve is staggered, the liquid channel is closed, the retaining ring is combined with the horse tooth buckle on the socket to fix the device, the sliding stops, the liquid passage of the multifunctional blowout preventer tail pipe and the annulus is closed, and the bottom of the tubing realizes the function of leakage and blowout prevention again.

[0046] Finally, it should be noted that the above 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 aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A process string for water injection well pressure operation, characterized in that: include: A casing (1) is provided, wherein an oil pipe (2) is passed through the casing (1), a blowout prevention mandrel (3), a production pipe string, and a multifunctional blowout prevention tail pipe (6) are arranged in sequence below the oil pipe (2), a screen pipe (7) is arranged at the end of the oil pipe (2), and a guide cone (8) is arranged below the screen pipe (7); a blowout prevention inner plug is arranged inside the blowout prevention mandrel (3), and the blowout prevention inner plug cooperates with the blowout prevention mandrel (3) to open the oil casing channel; the production pipe string comprises a plurality of matching packers (4) with an anti-mid-line setting design to separate the production pipe string into a plurality of layers, and each layer is provided with an anti-backflow water distributor (5) with a one-way valve function; the multifunctional blowout prevention tail pipe (6) comprises a lower valve body with a blowout prevention and leakage function and an upper valve body with a two-way valve function.

2. The process string for water injection well pressure operation according to claim 1, characterized in that: The blowout prevention working cylinder (3) comprises a sliding sleeve (13), a sliding sleeve retaining spring seat (12) is provided above the sliding sleeve (13); the sliding sleeve (13) is connected to the sliding sleeve retaining spring seat (12) and then inserted into the outer sleeve (10); a sliding sleeve upper joint (9) is provided above the sliding sleeve retaining spring seat (12), and the sliding sleeve upper joint (9) is inserted into the outer sleeve (10); the upper end of the outer sleeve (10) is threadedly connected to the sliding sleeve upper joint (9), and the lower end is threadedly connected to the sliding sleeve lower joint (15); the sliding sleeve (13) and the outer sleeve (10) are connected through the sliding sleeve The sleeve (10) is fixed with a pin (14); a cavity is provided between the lower end of the sleeve (13) in the sleeve (10) and the upper end of the sleeve lower joint (15); 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 part of the cavity inside the 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 end of the sleeve (13); a horse tooth buckle is provided inside the sleeve (10), and a sleeve liquid outlet is provided at the corresponding part of the sleeve (10) and the sleeve (13) groove.

3. The process string for water injection well pressure operation according to claim 1, characterized in that: The blowout prevention inner plug comprises an expansion sleeve (16), the expansion sleeve (16) is connected to the blowout prevention inner plug sealing sleeve (17) at the bottom, the blowout prevention inner plug sealing sleeve (17) is connected to the inner plug connecting sleeve (23) at the bottom, and the inner plug connecting sleeve (23) is connected to the conical head (24) at the bottom; the expansion sleeve (16) is provided with a spring claw at the top; the inner plug connecting sleeve (23) is provided with an axial guide groove inside, and a blowout prevention valve assembly (18) is provided on the guide groove, and the top of the blowout prevention valve assembly (18) is an upwardly tapered shape; the bottom of the blowout prevention inner plug sealing sleeve (17) is a tapered surface with a small top and a large bottom, and is connected to the blowout prevention valve assembly (18) at the bottom. The top of the component (18) is matched; a movable ball seat (21) is fixed in the inner plug connection sleeve (23) through a ball seat pin (22); an axial through hole is provided in the middle of the movable ball seat (21), 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 the diameter matches the guide surface at the upper end of the movable ball seat (21); an inner plug liquid outlet hole is provided in the circumferential direction of the inner plug connection sleeve (23) corresponding to the part below the movable ball seat (21); and a plurality of anti-blowout inner plug sealing rings (19) are provided on the anti-blowout inner plug sealing sleeve (17).

4. The process string for water injection well pressure operation according to claim 1, characterized in that: The matching packer (4) comprises a packer upper center tube (27), the upper end of the packer upper center tube (27) is connected to the packer upper joint (25), and an upper outer tube (26) is arranged outside the packer upper joint (25); a first well-washing valve (28) movable up and down is arranged between the upper outer tube (26) and the packer upper center tube (27), and the lower end of the first well-washing valve (28) is connected to a second well-washing valve (29); an inner casing (34) is arranged outside the packer upper center tube (27), and the inner casing (34) is located inside the second well-washing valve (29), a rubber tube group is sleeved on the inner casing (34); the rubber tube group includes two side rubber tubes (31) at the front and rear ends and a plurality of middle rubber tubes (33), and a spacer (32) is provided between two adjacent sections of rubber tubes; a packer pressure ring (36) is provided below the rubber tube group, and the packer pressure ring (36) is fixed to the end of the inner casing (34) through a sealing pin (37); a suspension body (38) is provided below the inner casing (34), and a packer retaining spring (39) is provided on the suspension body (38); a packer retaining spring (39) is provided outside the suspension body (38) A spring sleeve (40), the upper end of the packer spring sleeve (40) is connected to the packer pressure ring (36), and a horse tooth buckle is provided inside the packer spring sleeve (40); a lower outer sleeve (43) is provided below the packer spring sleeve (40), a packer lower center pipe (42) is provided below the packer upper center pipe (27), the lower outer sleeve (43) is sleeved outside the packer lower center pipe (42), and a piston (41) is provided in the pores among the packer spring sleeve (40), the packer upper center pipe (27), the packer lower center pipe (42) and the lower outer sleeve (43); A cylinder sleeve (44) is provided below the lower center tube (42) of the packer, and a lower joint (45) of the packer is provided inside the lower part of the cylinder sleeve (44); the upper part of the packer lower joint (45) is sleeved on the lower center tube (42) of the packer, and the lower outer sleeve (43) is connected to the cylinder sleeve (44); a first through hole is provided at a position between the upper center tube (27) of the packer corresponding to the piston (41) and the lower center tube (42) of the packer, and a second through hole is provided at a position between the lower center tube (42) of the packer corresponding to the cylinder sleeve (44) and the lower joint (45) of the packer.

5. The process string for water injection well pressure operation according to claim 4, characterized in that: The upper central tube (27) is provided with a third through hole at a position corresponding to between the upper outer tube (26) and the first well-washing valve (28); the portion of the upper central tube (27) where the inner sleeve (34) is installed is provided with a well-washing passage, and the inner sleeve (34) is provided with an upper well-washing hole and a lower well-washing hole at both ends; the upper well-washing hole and the lower well-washing hole are both connected to the well-washing passage.

6. The process string for water injection well pressure operation according to claim 1, characterized in that: The anti-backflow water distributor (5) comprises a main body (49), a side hole is provided in the main body (49), and a plug (53) is provided in the side hole; a ceramic ball (54) is provided in the water nozzle of the plug (53), and the diameter of the ceramic ball (54) matches the inner diameter of the plug (53) to form a one-way valve structure; the main body (49) is connected to a centralizing body (48) above, and a water distributor upper joint (46) is provided above the centralizing body (48); an upper connecting sleeve (47) is provided outside the centralizing body (48) to connect the centralizing body (48) and the water distributor upper joint (46) to the centralizing body (48). The upper end of the connecting sleeve (47) is connected to the upper joint (46) of the water distributor, and the lower end is connected to the main body (49); the lower part of the main body (49) is connected to the lower connecting sleeve (50), and the lower part of the lower connecting sleeve (50) is connected to the lower joint (51) of the water distributor via a fastening screw (55); a lower guide body (52) is provided in the lower joint (51) of the water distributor, an upper guide sleeve (56) is provided between the upper joint (46) of the water distributor and the straightening body (48), and an upper guide body (57) is provided in the upper guide sleeve (56).

7. The process string for water injection well pressure operation according to claim 1, characterized in that: The multifunctional blowout-preventing tail pipe (6) comprises an upper valve body and a lower valve body; the upper valve body comprises an upper center pipe (68) of the blowout-preventing tail pipe, and the lower valve body comprises a lower center pipe (75) of the blowout-preventing tail pipe; the lower end of the upper center pipe (68) of the blowout-preventing tail pipe is connected to the upper end of the lower center pipe (75) of the blowout-preventing tail pipe via a coupling (73); an upper sliding sleeve (62) is provided inside the upper center pipe (68) of the blowout-preventing tail pipe and is connected via a first pin (66) of the blowout-preventing tail pipe; a sealing sleeve (65) is provided outside the upper center pipe (68) of the blowout-preventing tail pipe and is connected via a second pin (67) of the blowout-preventing tail pipe; a threaded sleeve (61) is connected to the upper part of the sealing sleeve (65), a snap ring (64) is provided inside the threaded sleeve (61), and a snap ring seat (63) matching the snap ring (64) is provided at the top of the upper center pipe (68) of the blowout-preventing tail pipe; A blowout tail pipe upper joint (58) is provided above the tooth sleeve (61), and a ball baffle (59) with a through hole is provided inside the blowout tail pipe upper joint (58); the top end of the upper sliding sleeve (62) is inserted into the blowout tail pipe upper joint (58), the top is a downward guiding structure, and a blowout tail pipe steel ball (60) is provided between the upper sliding sleeve (62) and the blowout tail pipe upper joint (58); a pressure ring (70) is provided below the sealing sleeve (65), and a pressure ring sealing ring (69) is provided between the sealing sleeve (65) and the pressure ring (70); the bottom end of the pressure ring (70) is connected to the blowout tail pipe upper center pipe (68); an upper center pipe through hole is provided on the side of the blowout tail pipe upper center pipe (68) corresponding to the bottom of the pressure ring (70), and an upper sliding sleeve through hole is provided on the upper sliding sleeve (62) corresponding to the upper center pipe through hole.

8. The process string for water injection well pressure operation according to claim 6, characterized in that: The lower valve body comprises a lower central tube (75) of the blowout preventer tail pipe, a flow guide tube (77) is fixed outside the lower central tube (75) of the blowout preventer tail pipe, two ends of the flow guide tube (77) are in contact with the lower central tube (75) of the blowout preventer tail pipe, and a gap is provided between the middle part and the lower central tube (75) of the blowout preventer tail pipe; an upper retaining ring (74) is provided at the upper end of the lower central tube (75) of the blowout preventer tail pipe, 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; and a hole is provided above the lower retaining ring (81). A lower sleeve (78), a lower center tube spring (76) is provided between the upper part of the lower sleeve (78) and the upper retaining ring (74); an upward guiding structure is provided above the lower sleeve (78), 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 surface of the lower sleeve (78); an upper connecting hole and a lower connecting hole are provided at the upper and lower ends of the side surface of the lower center tube (75) of the blowout-proof tail pipe, which corresponds to the gap between the guide tube (77).

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