Multifunctional blowout prevention tail pipe of separate injection well

Abstract

The utility model belongs to the technical field of oil field underground operation, and discloses a multifunctional blowout prevention tail pipe of a separate injection well, which comprises a tail pipe body and a blanking plug, and the tail pipe body comprises a seat sealing section, a throttling deceleration section, a blocking section and a plug type ball seat section. The setting section comprises a setting pipe and a throttling speed reduction section, the blocking section is two parts of a speed reduction pipe, and the plug type ball seat section comprises a blocking pipe, a screen pipe, a plug, a ball seat and a steel ball. The tail of the setting pipe can be connected with an oil pipe, and the setting pipe, the speed reducing pipe, the blocking pipe and the screen pipe are sequentially connected. The inner diameter of the rear half section of the speed reducing pipe is smaller than that of the setting pipe, and the inner diameter of the front half section is further reduced; the plug is fixed through a shear pin and plugged in the rear section of the interior of the screen pipe, and a ball seat and a steel ball are installed in the plugging pipe. The blanking plug comprises a guide head, an expansion rubber sleeve, a compression rubber sleeve and a slip. The plug-in success rate is higher, and the plug-in effect is good under the working condition of larger underground pressure.

Description

Technical Field

[0001] The utility model belongs to the technical field of downhole operation in oil fields, and particularly relates to a multifunctional blowout-preventing tail pipe for a separate injection well. Background Art

[0002] Oilfields are typically composed of multiple reservoirs with varying permeabilities and physical properties. Separate layer water injection balances displacement pressure across each layer, ensuring that the injected water effectively displaces crude oil from the reservoir and improving overall recovery. Without separate layer water injection, high-permeability layers often flood first, impacting oil recovery from low-permeability layers. Separate layer water injection allows precise control of injection rates in high-permeability layers, preventing premature flooding and improving overall development effectiveness. By controlling the injection rate and pressure of each layer, stratified water injection prevents water breakthrough and ensures normal production and efficient oil recovery.

[0003] At present, a blowout-preventing tail pipe needs to be set at the bottom of the injection well to realize pressure operation. For example, a preset working cylinder disclosed in the Chinese invention patent with publication number CN108691516A, by inserting the push rod into the working cylinder, the conical block is moved into the conical hole to block it, thereby preventing the occurrence of a blowout. At the same time, the blocking block is located in the groove to fix the push rod, which is convenient for docking with the plug. This blowout-preventing tail pipe structure, in which the conical block and the fixed block are actually a one-way valve, is suitable for lowering the tubing string under pressure when the oil well pressure is relatively low. When dealing with some oil wells with deeper depths and higher pressures, it is still easy to overflow when lowering the tubing string. Moreover, there is room for improvement in the connection method of the plug, and the delivered plug still has the problem of multiple plugging.

[0004] The current new generation of blowout preventer tail pipe needs to achieve the following functions:

[0005] 1. The blowout-preventing tail pipe can be used to prevent blowout and overflow when the oil pipe is lowered under pressure;

[0006] 2. In subsequent oilfield operations, oil pumping and water injection operations are required. At this time, the blowout preventer tail pipe is required to ensure that the bottom oil pipe has the function of a one-way valve;

[0007] 3. After the oil pipe has been working for a long time, it is necessary to backwash the well. Inject water from the casing and enter the well from the blowout preventer tail pipe to backwash the well and remove all kinds of sediments and blockages from the bottom up in the oil pipe.

[0008] 4. When the oil pipe accessories encounter failure and well repair is required, the blowout preventer tail pipe is also needed to seal the oil pipe when the oil pipe is raised and lowered under pressure.

[0009] Designing a blowout preventer tail pipe to achieve the above functions and be suitable for working conditions with higher pressure and improve the success rate of well repair and plugging has become an urgent problem to be solved. Utility Model Content

[0010] In response to the above-mentioned shortcomings of the existing technology, the present invention aims to solve the problem that existing blowout preventer tail pipes or mandrels, while performing multiple functions such as blowout prevention, overflow prevention, one-way flow restriction, backwashing, and plugging the oil pipe during tripping, suffer from poor reliability when the oil pressure in the oil well is high, and the plug is prone to connection failure. The present invention provides a multifunctional blowout preventer tail pipe for injection wells, which can effectively perform multiple functions at higher pressures and has better connection and sealing effects when plugging.

[0011] In order to achieve the above purpose, the utility model provides a multifunctional blowout prevention tail pipe for injection wells, comprising: a tail pipe body, a plug, the tail pipe body comprising a sealing section, a throttling and deceleration section, a blocking section, and a plug-type ball seat section.

[0012] The seat seal section includes a seat seal pipe, a throttling and deceleration section and a blocking section as two parts of the deceleration pipe, and a plug type ball seat section includes a plugging pipe, a screen pipe, a plug, a ball seat, and a steel ball.

[0013] The tail of the seat seal tube can be connected to the oil pipe, and the seat seal tube, speed reducer, plugging tube and screen tube are connected in sequence; the inner diameter of the rear half of the speed reducer is smaller than that of the seat seal tube, and the inner diameter of the front half is further reduced; the plug is fixed by shear nails and sealed in the rear section of the screen tube, and a ball seat and a steel ball are installed in the plugging tube.

[0014] The plugger includes a guide head, an expansion rubber cylinder, a compression rubber cylinder, and a slip; the front part of the guide head is conical and cooperates with the inner wall of the speed reducer tube; the expansion rubber cylinder is installed at the rear of the guide head, and the expansion rubber cylinder includes multiple petals, which can open backward under pressure; the front part of the compression rubber cylinder contacts the movable column, and the rear part contacts the fixed column, the compression rubber cylinder, the movable column, and the fixed column are sleeved on the core shaft, and an inclined sliding column is provided at the rear of the fixed column, an inclined notch is provided on the inclined sliding column, and a sliding slip is installed on the inclined surface of the inclined notch.

[0015] According to another embodiment of the present invention or any of the preceding embodiments, a booster rubber sleeve is mounted behind the guide head. The booster rubber sleeve comprises a plurality of continuous tapered portions that each converge downward. The booster rubber sleeve is connected to the guide head via an internal stud. The booster rubber sleeve, the expansion rubber sleeve, and the compression rubber sleeve are made of a soft material, preferably rubber or resin.

[0016] According to another embodiment of the present invention or the tail pipe of any of the aforementioned embodiments, a limit rod is installed at the rear of the inclined sliding column, and the limit rod is detachably screwed on the inclined sliding column by a bolt; symmetrical grooves are provided on the inclined surface of the inclined sliding column, and the slips are buckled on the grooves.

[0017] According to another embodiment of the present invention or the tail pipe of any of the aforementioned embodiments, a bolt is connected to the rear of the core shaft, the bolt is screwed into the fixing column, and the lock buckle is installed on the bolt.

[0018] According to another embodiment of the present invention or the tail pipe of any of the aforementioned embodiments, a groove is provided inside the fixing column, and a sealing ring is installed in the groove to fit the cylindrical surface of the core shaft.

[0019] Beneficial effects of the utility model:

[0020] The multifunctional blowout-preventing tail pipe for injection wells described in the utility model can realize multiple functions such as blowout prevention, overflow prevention, one-way flow limiting, backwashing wells, and plugging of oil pipes when lifting and lowering oil pipes. At the same time, the connection structure between the plugger and the seat sealing pipe is more reasonable, the plugging success rate is higher, and it can achieve good plugging effect under higher downhole pressure conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a cross-sectional schematic diagram of the multifunctional blowout-preventing tail pipe for injection wells according to the present invention when plugging;

[0022] Figure 2 for Figure 1 An enlarged schematic diagram of part A;

[0023] Figure 3 This is a cross-sectional schematic diagram of the plug according to the present invention;

[0024] In the figure: 1. Screen tube; 2. Plug; 3. Shear pins; 4. Plug tube; 5. Ball seat; 6. Steel ball; 7. Speed ​​reducer; 8. Sealing tube; 9. Guide head; 10. Boosting rubber cylinder; 11. Expansion rubber cylinder; 12. Compression rubber cylinder; 13. Locking buckle; 14. Slip; 15. Core shaft; 16. Movable column; 17. Inclined sliding column; 18. Sealing ring; 19. Limit rod; 20. Fixed column. DETAILED DESCRIPTION

[0025] 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 embodiments described 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 shall fall within the scope of protection of the present invention.

[0026] like Figure 1 As shown, a multifunctional blowout-preventing tail pipe for injection wells includes: a tail pipe body and a plug. The tail pipe body includes a seating section, a throttling and deceleration section, a blocking section, and a plug with a 2-type ball seat.

[0027] The sealing section includes a sealing pipe 8, the throttling and deceleration section and the blocking section are two parts of the deceleration pipe 7, and the plug 2 type ball seat 5 section includes a plugging pipe 4, a screen pipe 1, a plug 2, a ball seat 5, and a steel ball 6.

[0028] like Figure 1As shown, the tail end of the seat sealing tube 8 can be connected to the oil pipe, and the seat sealing tube 8, the speed reducing tube 7, the plugging tube 4, and the screen tube 1 are connected in sequence; the inner diameter of the rear half of the speed reducing tube 7 is smaller than that of the seat sealing tube 8, and the inner diameter of the front half is further reduced; the plug 2 is fixed by shear nails 3 and sealed in the rear section inside the screen tube 1, and a ball seat 5 and a steel ball 6 are installed in the plugging tube 4.

[0029] like Figure 3 As shown, the plug includes a guide head 9, an expansion rubber sleeve 11, a compression rubber sleeve 12, and slips 14. The front portion of the guide head 9 is tapered and fits into the inner wall of the speed reducer 7. A booster rubber sleeve 10 is mounted behind the guide head 9. The booster rubber sleeve 10 comprises multiple continuous tapered portions that each contract downward. The booster rubber sleeve 10 is connected to the guide head 9 via an internal stud. The booster rubber sleeve 10, expansion rubber sleeve 11, and compression rubber sleeve 12 are made of a soft material, preferably rubber or resin.

[0030] like Figure 2 As shown, an expansion rubber cylinder 11 is mounted behind the guide head 9. The expansion rubber cylinder 11 includes multiple petals that can expand backward under pressure. The front of the compression rubber cylinder 12 contacts the movable column 16, and the rear contacts the fixed column 20. The compression rubber cylinder 12, movable column 16, and fixed column 20 are sleeved on the core shaft 15. The rear of the core shaft 15 is connected to a bolt, which is screwed into the fixed column 20. The lock 13 is mounted on the bolt. The lock 13 prevents the bolt from rotating, avoiding the structure of the core shaft 15, expansion rubber cylinder 11, and compression rubber cylinder 12 from being separated.

[0031] When the downhole pressure is not high, the expansion rubber cylinder 11 contacts the sealing tube 8 to seal; when the downhole pressure is high, the compression rubber cylinder 12 is compressed to effectively improve the pressure resistance level and withstand high pressure.

[0032] An oblique sliding column 17 is provided behind the fixed column 20, and an oblique notch is provided on the oblique sliding column 17. The inclined surface of the oblique notch is provided with a sliding slip 14. A groove is provided inside the fixed column 20, and a sealing ring 18 is installed in the groove to fit the cylindrical surface of the core shaft 15.

[0033] like Figure 1 As shown, a limit rod 19 is installed at the rear of the inclined sliding column 17, and the limit rod 19 is detachably screwed on the inclined sliding column 17 by bolts; symmetrical grooves are set on the inclined surface of the inclined sliding column 17, and the slips 14 are buckled in the grooves to prevent them from falling off during sliding.

[0034] The working principle of this utility model:

[0035] like Figure 1 As shown, the utility model is divided into a seating section A, a throttling and deceleration section B, a blocking section C, and a plug 2-type ball seat 5 section D.

[0036] The utility model is installed on the oil pipe through the connecting buckle. When the oil pipe is lowered, the pipe of the utility model is mainly subjected to the upward pressure of the downhole oil. The plug 2 is acted upon by the shear nails 3 to seal the blocking pipe 4 to prevent the oil from overflowing when the oil pipe is lowered.

[0037] When injecting water and pumping oil, first use a cement truck to inject water. Under the action of pressure, the steel ball 6 pushes the plug 2, overcoming the connection effect of the shear nail 3 and pushing the plug 2 to the Figure 1 In the screen tube 1 shown, steel ball 6 now fits in a tapered ball seat 5. During water injection, the water flow creates a seal between the steel ball 6 and the ball seat 5, injecting water into the oil layer above the tail pipe. During oil pumping, negative pressure forces the oil from the ball seat 5 into the tail pipe and then into the oil pipeline, allowing normal operation.

[0038] When backwashing the well, water is injected into the outer casing of the oil pipe. High-pressure water enters the screen pipe 1 from the hole of the screen pipe 1, enters the tail pipe through the ball seat 5, and then enters the oil pipe, flushing the residue attached to the oil pipe.

[0039] When a well repair is required, the plugging device is deployed, and high-pressure water pushes the booster rubber cylinder 10, which quickly passes through the water distributor and enters the sealing pipe 8 at the bottom of the oil pipe. When the guide head 9 enters the speed reducer 7 in the throttling and deceleration section, it is throttled and decelerated due to the smaller pipe diameter and the reduced return water gap. Finally, it enters the blocking section of the speed reducer 7, and the guide head 9 is squeezed and stopped by the front of the speed reducer 7. At this time, the slips 14 slide down along the inclined sliding column 17 under the action of inertia and gravity, and the outer side contacts the inner wall of the sealing pipe 8. Downhole oil passes through the ball seat 5 and upward over the booster rubber cylinder 10, pushing the petal-shaped expansion rubber cylinder 11. After the expansion rubber cylinder 11 opens, it drives the movable column 16 to move backward. Because the slips 14 at the rear of the plug are in contact with the inner wall of the sealing tube 8, after being pushed upward, the slips 14 are acted upon by the inclined force of the inclined sliding column 17, tightly locking the sealing tube 8, thereby fixedly connecting with the sealing tube 8. The movable column 16 moves upward, and the compression rubber cylinder 12 is squeezed by the active column 16 and slips 14, so that it is in close contact with the sealing tube 8, achieving a high pressure sealing and blocking the continued upward movement of the oil. The core shaft 15 is provided with a sealing ring 18 to prevent oil from leaking from the core shaft 15 inside the compression rubber cylinder 12.

[0040] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the above embodiments are merely illustrative of the technical concepts and features of the present invention, and are intended to enable those familiar with the art to understand and implement the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications based on the spirit and substance of the present invention are intended to fall within the scope of protection of the present invention.

Claims

1. A multifunctional blowout preventer tail pipe for injection wells, characterized by: include: Tail pipe body, plug, the tail pipe body includes a seat sealing section, a throttling and deceleration section, a blocking section, a plug (2) type ball seat (5) section, The sealing section includes a sealing pipe (8), a throttling and deceleration section and a blocking section are two parts of a deceleration pipe (7), and the plug (2) type ball seat (5) section includes a plugging pipe (4), a screen pipe (1), a plug (2), a ball seat (5), and a steel ball (6). The tail of the seat sealing tube (8) can be connected to the oil pipe, and the seat sealing tube (8), the speed reducing tube (7), the plugging tube (4), and the screen tube (1) are connected in sequence; the inner diameter of the rear half of the speed reducing tube (7) is smaller than that of the seat sealing tube (8), and the inner diameter of the front half is further reduced; the plug (2) is fixed by shear nails (3) and is plugged in the rear section of the screen tube (1); a ball seat (5) and a steel ball (6) are installed in the plugging tube (4). The plugger comprises a guide head (9), an expansion rubber cylinder (11), a compression rubber cylinder (12), and a slip (14); the front portion of the guide head (9) is conical and matches the inner wall of the deceleration tube (7); an expansion rubber cylinder (11) is installed at the rear of the guide head (9), and the expansion rubber cylinder (11) comprises a plurality of petals, which can be opened backward under pressure; the front portion of the compression rubber cylinder (12) contacts the movable column (16), and the rear portion contacts the fixed column (20); the compression rubber cylinder (12), the movable column (16), and the fixed column (20) are sleeved on the core shaft (15); an inclined sliding column (17) is provided at the rear of the fixed column (20); an inclined notch is provided on the inclined sliding column (17), and a sliding slip (14) is installed on the inclined surface of the inclined notch.

2. The multifunctional blowout preventer tail pipe for injection wells according to claim 1, characterized in that: A booster rubber cylinder (10) is installed behind the guide head (9). The booster rubber cylinder (10) includes a plurality of continuous tapered portions, each of which contracts downward. The booster rubber cylinder (10) is connected to the guide head (9) via an internal stud bolt.

3. A multifunctional blowout preventer tail pipe for injection wells according to claim 1 or 2, characterized in that: A limiting rod (19) is installed at the rear of the inclined sliding column (17), and the limiting rod (19) is detachably screwed on the inclined sliding column (17) through a bolt; symmetrical grooves are provided on the inclined surface of the inclined sliding column (17), and the slips (14) are buckled on the grooves.

4. A multifunctional blowout preventer tail pipe for injection wells according to claim 1 or 2, characterized in that: The rear portion of the core shaft (15) is connected with a bolt, which is screwed into the fixing column (20), and the lock buckle (13) is installed on the bolt.

5. The multifunctional blowout preventer tail pipe for injection wells according to claim 1 or 2, characterized in that: A groove is provided inside the fixing column (20), and a sealing ring (18) is installed in the groove to fit the cylindrical surface of the core shaft (15).

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