Differential pressure type forward and reverse washing plugging assembly

Abstract

A differential pressure type forward and reverse washing plugging assembly can complete tripping-in of a water well pipe column under the low-pressure well condition, the whole operation process is safe and environmentally friendly, and the operation efficiency is high. Comprising a punching outer pipe, an upper connector, a lower plug, a centralizing rod, a core pipe, a sliding sleeve, a well washing outer sleeve, a well washing valve, a pressure maintaining spring, a ball seat, a lower valve ball and a ball pressing spring, the sliding sleeve is installed on the inner wall of the core pipe through a shear pin, and a first radial through hole and a second radial through hole are formed in the surface of the sliding sleeve and the surface of the core pipe in an up-down staggered mode respectively; an annular shoulder is arranged on the lower portion of the inner wall of the core pipe, a third radial through hole is formed in the position, corresponding to the well washing valve, of the well washing outer sleeve, an axial stress face communicated with the third radial through hole is arranged on the surface of the well washing valve, the pressure maintaining spring is arranged between the well washing valve and the ball seat, and the centralizing rod is sleeved with the ball pressing spring. The lower valve ball plugs the lower end opening of the ball seat through the ball pressing spring; an axial through hole is formed in the lower plug, and a communicating channel is formed in the position, below the ball seat, of the well washing outer sleeve.

Description

Technical Field

[0001] This invention belongs to the field of petroleum extraction technology, and in particular relates to a differential pressure forward and reverse washing and plugging assembly with injection and well washing function. Background Technology

[0002] As oil and gas field development deepens, well maintenance is becoming increasingly frequent. Traditional maintenance methods typically employ high-density kill fluids or blowout techniques to reduce well pressure for operation. High-density kill fluids involve injecting brine or brine with added chemicals into the well to force out the oil-water mixture, thus lowering well pressure. However, using high-density kill fluids not only increases operating costs but can also clog oil-water channels, affecting oil production efficiency and water injection effectiveness. Blowout techniques directly discharge the oil-water mixture through the wellhead. Direct discharge to the surface can pollute the environment, and pressurized discharge poses safety hazards. Recovering the mixture using recovery equipment increases equipment procurement costs and requires secondary processing, increasing transportation and disposal costs. In contrast, pressurized operation equipment demonstrates unique advantages in water well maintenance, minimizing disturbance to the formation and reducing its impact on the formation and surrounding environment. Existing live well operation equipment is complex in structure and expensive, requires professional personnel to operate on-site, and is limited in number due to cost constraints. When all live wells are operated under pressure, the operation efficiency is low, which affects oil production. Summary of the Invention

[0003] The purpose of this invention is to solve the aforementioned problems in the background technology and provide a differential pressure forward and reverse washing and plugging assembly. The equipment has a simple structure, low cost, and can complete the installation of water well tubing under low-pressure well conditions. The entire operation process is safe and environmentally friendly, and the operation efficiency is high. The technical solution of this invention is: a differential pressure forward and reverse washing and plugging assembly, including a perforated outer tube, an upper connector and a lower plug connected to the upper and lower ports of the perforated outer tube respectively, and a centering rod installed at the center of the lower plug. Its special feature is that it also includes a core tube, a sliding sleeve, a well-washing outer sleeve, a well-washing valve, a pressure holding spring, a ball seat, a lower valve ball, and a pressure ball spring. The core tube is connected to the lower port of the upper connector. The core tube is vertically connected to the well-washing outer sleeve. The sliding sleeve is installed on the inner wall of the core tube by a shear pin. The upper port of the sliding sleeve is a valve seat. The sliding sleeve and the surface of the core tube are respectively provided with radially staggered through holes one and two. The lower part of the inner wall of the core tube is provided with an annular shoulder, which is the lower stop point of the sliding sleeve movement. After the upper valve ball is inserted into the upper connector and pressurized, the sliding sleeve moves down to the lower stop position so that radial through hole one and radial through hole two are radially connected; the well washing valve and the ball seat are installed inside the well washing outer sleeve and arranged vertically. A radial through hole three is provided on the surface of the well washing outer sleeve corresponding to the well washing valve. The surface of the well washing valve is provided with an axial force-bearing surface that communicates with the radial through hole. The pressure holding spring is set between the well washing valve and the ball seat. The pressure ball spring is fitted outside the straightening rod. The lower valve ball is set on the pressure ball spring and the lower port of the ball seat is sealed by the pressure ball spring; the lower plug is provided with an axial through hole. The well washing outer sleeve is located below the ball seat and has a connecting channel that connects the well washing outer sleeve and the perforated outer pipe and connects the well washing outer sleeve and the axial through hole.

[0004] Furthermore, an annular step is provided on the outer circumferential surface of the well-washing valve below the radial through hole three to form the axial force-bearing surface.

[0005] Furthermore, a sealing ring is provided at the connection between the core tube and the well washing outer sleeve.

[0006] Furthermore, a pressure cap is installed at the lower end of the well-washing outer casing below the ball seat, and the pressure cap is locked to the well-washing outer casing by threads.

[0007] Furthermore, there are at least two radial through holes, radial through holes 1, 2, 3 and axial through holes, which are evenly distributed along the circumferential direction.

[0008] Furthermore, the surface of the sliding sleeve is provided with an annular groove that communicates with the radial through hole.

[0009] Furthermore, the upper connector and the core tube, the sliding sleeve and the core tube, the well-washing valve and the well-washing outer sleeve, and the ball seat and the well-washing outer sleeve are sealed by a second sealing ring.

[0010] Furthermore, the second sealing ring is respectively embedded on the surface of the upper connector, the sliding sleeve, the well-washing valve, and the ball seat.

[0011] Furthermore, the upper connector and the perforated outer tube, the lower plug and the perforated outer tube, and the core tube and the upper connector are respectively connected by threads.

[0012] Furthermore, the well-washing jacket is suspended below the ball seat, and the suspended portion forms the connecting channel.

[0013] The beneficial effects of this invention are: simple operation, reasonable structure, and full functionality. It is suitable for pressurized operations, wells with oil caps, and high-wax water wells, improving operational efficiency, ensuring well control safety during operations, and replacing the original tubing ball seat without adding other tools. This invention has a pressure control function, which can effectively prevent overflow; it has forward and reverse well washing functions, allowing for continuous well washing; and it has a secondary setting function. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the core tube structure; Figure 3 This is a schematic diagram of the sleeve structure; Figure 4 yes Figure 3 AA section view; Figure 5 This is a schematic diagram of the perforated outer tube structure; Figure 6 This is a schematic diagram of the well cleaning jacket structure; Figure 7 This is a schematic diagram of the lower plug structure.

[0015] In the diagram: Upper connector-1, core tube-2, sliding sleeve-3, perforated outer tube-4, well washing outer sleeve-5, sealing ring one-6, well washing valve-7, pressure holding spring-8, ball seat-9, pressure cap-10, lower valve ball-11, pressure ball spring-12, straightening rod-13, lower plug-14, upper valve ball-15, sealing ring two-16, shear pin-17, connecting channel-18, radial through hole two-201, annular shoulder-202, radial through hole one-301, annular groove-302, inlet / outlet hole-401, radial through hole three-501, axial force-bearing surface-701, axial through hole-1401. Detailed Implementation

[0016] The accompanying drawings are intended only to illustrate and explain the present invention and do not limit the scope of the invention. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principles of the present invention should fall within the scope of protection of the invention.

[0017] As shown in the figure, a differential pressure type forward and reverse flushing and plugging assembly includes an upper connector 1, a core tube 2, a sliding sleeve 3, a perforated outer tube 4, a well-washing outer sleeve 5, a well-washing valve 7, a pressure holding spring 8, a ball seat 9, a pressure cap 10, a lower valve ball 11, a pressure ball spring 12, a straightening rod 13, a lower plug 14, and an upper valve ball 15. The upper connector 1 and the upper port of the perforated outer tube 4, as well as the lower plug 14 and the lower port of the perforated outer tube 4, are respectively connected by threads. The surface of the perforated outer tube 4 is provided with four rows of inlet and outlet holes 401 evenly distributed along the circumferential direction. The core tube 2 is connected to the lower port of the upper connector 1 by threads. The lower port of the core tube 2 is connected to the well-washing outer sleeve 5 by threads, and a rubber sealing ring 6 is provided at the position corresponding to the outer surface of the well-washing valve 7. The sliding sleeve 3 is installed on the inner surface of the core tube 2 by the shear pin 17. The upper end of the sliding sleeve 3 is a valve seat corresponding to the upper valve ball 15. The sliding sleeve 3 and the surface of the core tube 2 are respectively provided with radial through holes 301 and 201 arranged vertically and vertically. The outer surface of the sliding sleeve 3 is provided with an annular groove 302 communicating with the radial through hole 301. The lower part of the inner wall of the core tube 2 is provided with an annular shoulder 202. The annular shoulder 202 is the lower stop point of the sliding sleeve 3. When the valve ball is inserted into the upper connector and pressed, the sliding sleeve 3 moves down to the lower stop point position so that the radial through hole 301 and the radial through hole 201 are radially connected. The well-washing valve 7 is slidably installed inside the upper port of the well-washing outer sleeve 5. The ball seat 9 and the pressure cap 10 are installed from top to bottom at the lower port 9 of the well-washing outer sleeve 5, and the pressure cap 10 is threadedly locked to the lower port of the well-washing outer sleeve 5. A radial through hole 3 501 is provided on the well-washing outer sleeve 5 corresponding to the well-washing valve 7. An annular step is provided on the outer circumference of the well-washing valve 7 below the radial through hole 3 501 to form an axial force-bearing surface 701 communicating with the radial through hole 3 501. The pressure holding spring 8 is disposed between the well-washing valve 7 and the ball seat 9. The straightening rod 13 is threaded to the center of the lower plug 14. The ball spring 12 is fitted onto the outside of the straightening rod 13. The lower end of the ball seat 9 is a valve seat. The lower valve ball 11 is set on the ball spring 12 and sits on the ball seat 9 through the ball spring 12 to seal the lower end of the ball seat 9. In this example, the lower plug 14 has four axial through holes 1401 distributed along the circumference. There are two radial through holes 301, 201, and 501, which are all elongated holes and are evenly distributed along the circumference. The well-washing sleeve 5 is suspended below the ball seat 9, and the suspended part forms a connecting channel 18 that connects the well-washing sleeve 5 and the perforated outer tube 4, and connects the well-washing sleeve 5 and the axial through holes 1401.

[0018] Furthermore, the upper connector 1 and the core tube 2, the sliding sleeve 3 and the core tube 2, the well-washing valve 7 and the well-washing outer sleeve 5, and the ball seat 9 and the well-washing outer sleeve 5 are sealed by rubber sealing rings 16 respectively embedded on the surfaces of the upper connector 1, the sliding sleeve 3, the well-washing valve 7 and the ball seat 9.

[0019] Working principle: When running into the well, this differential pressure forward and reverse flushing and plugging assembly is connected to the bottom of the tubing string to replace the original ball seat. This differential pressure forward and reverse flushing and plugging assembly can perform the following functions: 1. Sealing function: When the pressure difference between the external and internal pressures of the oil casing is less than 0.5 MPa, the oil pipe is in a sealed state.

[0020] 2. Differential pressure maintenance function: When the pressure difference between the external pressure and the internal pressure is greater than or equal to 0.5MPa (set between 0.5 MPa and 1MPa), the axial force-bearing surface 701 (compression spring 8) of the well washing valve 7 is subjected to force to maintain the oil casing pressure difference.

[0021] 3. Reverse washing function: For forward washing, the washing fluid is injected into the tubing, increasing the pressure inside the tubing. The hydraulic pressure pushes the lower valve ball 11 downwards to the open position (at this time, the washing valve 7 is in the pressure balance closed position). The compressed ball spring 12 moves downwards synchronously, creating an inlet / outlet channel between the washing outer sleeve 5 and the lower plug 14, thus completing the forward washing. For reverse washing, as the external pressure increases, the washing fluid enters through the perforated outer tube 4 and radial through-hole 3 501, applying a downward force to the axial force-bearing surface 701. The washing valve 7 moves downwards and opens (at this time, the lower valve ball 11 is in the closed position). The washing fluid enters the tubing through the exposed radial through-hole 3 501 and flows out through the upper port of the upper connector 1, directly performing reverse circulation washing.

[0022] 4. Sealing function: When the tubing string is lowered to the designated position, the upper valve ball 15 is inserted. The upper valve ball 15 falls onto the upper part of the sliding sleeve 3. The pump truck pressurizes the pressure to 5-8 MPa, shearing the shear pin 17, so that the radial through hole 301 on the sliding sleeve 3 connects with the radial through hole 201 on the core tube 2. At this time, continued pressurization can set the packer. If well flushing is required later in the water injection tubing string, the flushing fluid can return to the surface through this channel to reduce throttling.

[0023] The above are merely specific embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A differential pressure type forward and reverse flushing plugging assembly, comprising a perforated outer tube, an upper connector and a lower plug respectively connected to the upper and lower ends of the perforated outer tube, and a centering rod installed at the center of the lower plug, characterized in that: It also includes a core tube, a sliding sleeve, a well-washing outer sleeve, a well-washing valve, a pressure holding spring, a ball seat, a lower valve ball, and a pressure ball spring. The core tube is connected to the lower port of the upper connector, and the core tube and the well-washing outer sleeve are connected vertically. The sliding sleeve is installed on the inner wall of the core tube by a shear pin. The upper port of the sliding sleeve is a valve seat. The sliding sleeve and the surface of the core tube are respectively provided with radial through holes one and two arranged vertically and vertically. The lower part of the inner wall of the core tube is provided with an annular shoulder, which is the lower stop point of the sliding sleeve movement. When the upper valve ball is inserted into the upper connector and pressure is applied, the sliding sleeve moves down to the lower stop point position, causing radial through holes one and two to intersect. Two radially connected components; the well-washing valve and the ball seat are installed inside the well-washing outer sleeve and arranged vertically. A radial through hole is provided on the surface of the well-washing outer sleeve corresponding to the well-washing valve. The surface of the well-washing valve is provided with an axial force-bearing surface that communicates with the radial through hole. The pressure holding spring is set between the well-washing valve and the ball seat. The pressure ball spring is sleeved outside the straightening rod. The lower valve ball is set on the pressure ball spring and the lower port of the ball seat is sealed by the pressure ball spring. An axial through hole is provided on the lower plug. The well-washing outer sleeve is located below the ball seat and has a connecting channel that connects the well-washing outer sleeve and the perforated outer pipe, as well as the well-washing outer sleeve and the axial through hole.

2. The differential pressure type forward and reverse flushing sealing assembly according to claim 1, characterized in that: An annular step is provided on the outer circumferential surface of the well-washing valve below the radial through hole three to form the axial force-bearing surface.

3. The differential pressure type forward and reverse flushing sealing assembly according to claim 1, characterized in that: A sealing ring is provided at the connection between the core tube and the well washing outer sleeve.

4. The differential pressure type forward and reverse flushing sealing assembly according to claim 1, characterized in that: A pressure cap is installed at the lower end of the well cleaning jacket below the ball seat, and the pressure cap is locked to the well cleaning jacket by threads.

5. The differential pressure type forward and reverse flushing sealing assembly according to claim 1, characterized in that: There are at least two radial through holes, radial through holes one, radial through holes two, radial through holes three, and axial through holes, which are evenly distributed along the circumferential direction.

6. The differential pressure type forward and reverse flushing sealing assembly according to claim 1, characterized in that: The surface of the sliding sleeve is provided with an annular groove that communicates with the radial through hole.

7. The differential pressure type forward and reverse flushing sealing assembly according to claim 1, characterized in that: The upper connector and the core tube, the sliding sleeve and the core tube, the well-washing valve and the well-washing outer sleeve, and the ball seat and the well-washing outer sleeve are sealed by a second sealing ring.

8. The differential pressure type forward and reverse flushing sealing assembly according to claim 7, characterized in that: The second sealing ring is respectively embedded on the surface of the upper connector, the sliding sleeve, the well washing valve, and the ball seat.

9. The differential pressure type forward and reverse flushing sealing assembly according to claim 1, characterized in that: The upper connector is connected to the perforated outer tube, the lower plug is connected to the perforated outer tube, and the core tube is connected to the upper connector via threads.

10. The differential pressure type forward and reverse flushing sealing assembly according to claim 1, characterized in that: The lower part of the well-washing jacket is suspended in the air, and the suspended part forms the connecting channel.

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