Constant-flow water injection tool for injection and production well in same well

Abstract

The invention relates to the technical field of oil production engineering, in particular to a constant-flow water injection tool for a same-well injection and production well. The constant-flow water injection tool for the same-well injection and production well comprises a device body with the lower portion connected with a screen plug, a plunger body moving up and down is arranged in the device body, a plunger spring is arranged at the top end of the plunger body, through-flow holes are symmetrically formed in the side faces of the plunger body and correspond to liquid outlet holes in the side faces of the device body, and a sealing ring is arranged at the position, above the liquid outlet holes, of the plunger body. A pressing cap made of the same material as the sealing ring is arranged above the sealing ring to press the sealing ring to enable the sealing ring to be in interference fit, a pressure transmitting hole is formed in the upper portion of the outer wall of the device body, and a stress piece is arranged below the plunger body. According to the constant-flow water injection tool for the injection and production well in the same well, the pressure transmitting hole is formed, and the pressing cap is used for pressing the sealing ring to be matched with the pressure transmitting hole, so that reciprocating motion of the spring under frequent pressure fluctuation is reduced, and the service life of water injection equipment is prolonged; and the through-flow area between the through-flow hole and the liquid outlet hole is changed by changing the position of the plunger main body along with pressure, so that constant-flow water injection is kept.

Description

Technical Field

[0001] The invention relates to the technical field of oil production engineering, and in particular to a constant flow water injection tool for a same-well injection and production well. Background Art

[0002] The injection and production technology in the same well uses a downhole separation device to separate the produced fluid underground. The separated oil is produced from the ground by the production pump, and the separated water is directly injected back into the formation by the injection pump. In actual work, due to the different produced fluid volumes in different layers, the formation energy that needs to be supplemented is also different, so it is necessary to quantitatively inject water into different layers of the injection and production well in the same well. Since the surface of the injection and production well in the same well uses a pumping unit for production, the pressure changes frequently during the up and down strokes of the pumping unit, which greatly increases the number of repeated movements of the water replenishment tool spring. In addition, the downhole tool section of the injection and production well in the same well is relatively complex, and the operating cost is extremely high. The water replenishment tool needs to be lowered into the well with the downhole tool section. Under the limitations of the working environment, the equipment cannot be cast and salvaged like the constant flow plug used in conventional water injection wells. The working life needs to reach two and a half years, and according to the number of strokes of the surface pumping unit in the injection and production well in the same well, the service life of the water replenishment tool spring is required to reach tens of millions of times.

[0003] In the prior art, there is a constant flow plug for ordinary water injection wells for constant flow water injection into the target formation, and its spring life is generally one million times, which cannot meet the technical requirements of long-term quantitative water replenishment for injection and production wells in the same well. Therefore, in view of the above shortcomings, a constant flow water injection tool for injection and production wells in the same well is proposed. Summary of the invention

[0004] 1. Technical issues to be resolved In view of the deficiencies in the prior art, the present invention provides a constant flow water injection tool for injection and production wells in the same well, which solves the problem that the existing constant flow water injection device has a short service life and cannot meet the process requirements of injection and production wells in the same well.

[0005] (II) Technical solution In order to solve the above problems, the present invention provides a constant flow water injection tool for a same-well injection and production well, comprising: a device body, a plunger body and a screen plug; The plunger body is installed in the device body, and the bottom of the device body is connected to a screen plug; the plunger body is tubular and sealed at the top; two flow holes are symmetrically arranged on the side of the plunger body, and four liquid outlet holes are evenly arranged on the side of the device body in a circumferential direction; the flow holes correspond to the positions of the liquid outlet holes, and the liquid can flow out of the device body through the flow holes and the liquid outlet holes after flowing into the plunger body from the bottom; a plunger spring is arranged on the top of the plunger body; a pressure transmission hole is arranged on the side of the device body, and the pressure transmission hole is located above the plunger body to relieve the pressure between the plunger body and the device body to reduce the downward pressure on the plunger body; a sealing ring is arranged on the outside of the plunger body above the liquid outlet hole, and a pressure cap is arranged above the sealing ring to squeeze the sealing ring to make it interfere, and the friction force generated by the interference part and the device body cooperates with the pressure transmission hole to balance the thrust of the spring after compression; a detachable force-bearing sheet is arranged below the plunger body, and the size of the constant flow rate of the constant flow water injection tool is adjusted by changing the area of ​​the force-bearing sheet.

[0006] Preferably, the pressing cap and the sealing ring are made of the same material, both of which are polytetrafluoroethylene.

[0007] Preferably, a vertical straightening rod is provided on the top of the plunger body, and the plunger spring is sleeved on the straightening rod.

[0008] Preferably, the device body and the screen plug are connected via threads.

[0009] Preferably, a plunger cap is provided at the bottom of the plunger body, and the force-bearing sheet is installed in the plunger cap.

[0010] Preferably, a plurality of O-type packings are respectively provided on the top of the device body and the bottom of the screen plug.

[0011] Preferably, the pressure cap is connected to the plunger body via threads, and the pressure cap presses the sealing ring by tightening the threads.

[0012] Preferably, the plunger cap is detachably connected to the plunger body.

[0013] (III) Beneficial effects The constant flow water injection tool for injection and production wells provided by the present invention has a pressure transmission hole on the device body, and the pressure between the device body and the plunger body is relieved during the downstroke of the oil pump to reduce the downward pressure received by the plunger body. At the same time, the downward pressure received by the plunger body can be balanced after the sealing ring is compressed by the pressure cap and the pressure reduction effect of the pressure transmission hole, thereby reducing the number of reciprocating motions of the plunger spring and improving the service life of the device; by providing a force-bearing plate, which cooperates with the top spring, the overlapping area of ​​the flow hole and the liquid outlet hole is changed as the pressure changes, thereby ensuring that the device can achieve quantitative water replenishment under constantly changing pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic structural diagram of a constant flow water injection tool for a same-well injection and production well according to the present invention.

[0015] Among them, 1. plunger spring; 2. device body; 3. pressure transmission hole; 4. liquid outlet hole; 5. straightening rod; 6. plunger body; 7. pressure cap; 8. sealing ring; 9. force plate; 10. plunger cap; 11. screen plug; 12. O-type packing. Implementation

[0016] 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.

[0017] 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.

[0018] like Figure 1 As shown, the present invention provides a constant flow water injection tool for a same-well injection and production well, which specifically includes: a device body 2, a plunger body 6 and a screen plug 11.

[0019] The device body 2 is a hollow tube, and the plunger body 6 is inserted into the device body 2 and can move freely up and down in the device body 2; the lower end of the device body 2 is threadedly connected to the top of the screen plug 11, and the lower end of the screen plug 11 is provided with a plurality of water grooves. After the device is lowered into the well, the downhole liquid enters the device through the water groove below the screen plug 11 during the upward stroke of the oil pump. The screen plug 11 plays a filtering role to prevent large particles of impurities in the well from entering the device and clogging the device, thereby maintaining the normal operation of the device.

[0020] In the present invention, the plunger body 6 is tubular, sealed at the top, and two flow holes are symmetrically arranged on the side of the plunger body 6. The side of the device body 2 is provided with four liquid outlet holes 4 arranged circumferentially and perforated radially. During operation, liquid enters the device and injects water into the surrounding formations through the flow holes and the liquid outlet holes 4. During downhole operation, the position of the plunger body 6 is changed as the pressure changes, so that the flow area of ​​the liquid outlet hole 4 changes as the downhole pressure changes, so that the device has a constant water injection volume under different pressures. During operation, the device is lowered into the well. During the upstroke of the oil pump on the well, the liquid in the well enters the device through the water trough below the screen plug 11, flows into the plunger body 6 from bottom to top, and pushes the plunger body 6 upward. When the flow hole coincides with the liquid outlet hole 4, the liquid flows out of the device through the liquid outlet hole 4 and is injected into the surrounding formations.

[0021] Among them, a vertically placed plunger spring 1 is provided between the top of the plunger body 6 and the device body 2. When the plunger body 6 moves upward, the plunger spring 1 is compressed and applies a downward thrust to the plunger body 6 to prevent the plunger body 6 from moving too far upward, causing the liquid outlet 4 on the plunger body 6 to be misaligned with the liquid outlet 4 on the device body 2, resulting in the liquid being unable to flow out of the device and the water injection operation being unable to be performed.

[0022] It should be noted that a vertical straightening rod 5 is provided at the top of the plunger body 6, and the plunger spring 1 is passed through the straightening rod 5 to ensure the correct direction of the plunger spring 1 and prevent the plunger spring 1 from bending and deforming due to force during operation, thereby improving the stability of the device and reducing the probability of device failure.

[0023] like Figure 1As shown, a sealing ring 8 is provided on the plunger body 6 above the liquid outlet 4, and the sealing ring 8 is interference-connected between the device body 2 and the plunger body 6. A pressure cap 7 is provided above the sealing ring 8, and the pressure cap 7 is connected to the plunger body 6 by threads. After the pressure cap 7 is tightened with threads, the sealing ring 8 is squeezed. Since the sealing ring 8 has an interference fit during the installation process, the pressure between the sealing ring 8 and the device body 2 increases, thereby increasing the friction between the sealing ring 8 and the device body 2. A pressure transmission hole 3 is provided on the side of the device body 2, and the pressure transmission hole 3 is located above the plunger body 6. During operation, the pressure transmission hole 3 can unload the pressure in the device, thereby reducing the downward pressure on the plunger body 6; the friction between the sealing ring 8 and the device body 2 cooperates with the pressure relief effect of the pressure transmission hole 3 to balance the elastic force of the plunger spring 1 after compression. After the device is lowered into the well for the first time, when it passes through the upstroke of the well pumping unit for the first time, the liquid below the device enters the device through the screen plug 11 and pushes the plunger body 6 upward. When it moves to a certain position, the thrust from the liquid below, the downward elastic force from the plunger spring 1 and the friction force from the sealing ring 8 on the plunger body 6 are zero, the plunger body stops moving upward, and the liquid is injected into the target formation from the liquid outlet hole. Afterwards, the friction between the sealing ring 8 and the device body 2 and the pressure relief effect of the pressure transmission hole 3 balance the elastic force of the plunger spring 1 after compression, and the plunger body 6 is formed in the device body 2. The piston body 6 is self-locking and fixed in position. The position hardly changes in the subsequent working process. During the downstroke of the well pumping unit, the downward pressure sometimes pushes the plunger body 6 downward. Then, in the next upstroke, the plunger body 6 repeats the above process to reach the self-locking position again, and the cycle repeats. During the working process, the plunger body 6 remains in the self-locking state most of the time, and the plunger spring 1 always remains in a compressed state, which greatly reduces the number of actions of the plunger spring 1, thereby greatly extending the service life of the plunger spring 1, so that it meets the technical requirements of quantitative water replenishment for the formation in the same well injection and production well. There is no need to repeatedly operate the water injection device, save work intensity and construction costs, and replenish energy for the target formation through quantitative water replenishment, which helps to increase production and improve economic benefits.

[0024] Among them, if the strength of the pressing cap 7 is greater than that of the sealing ring 8, the sealing ring 8 is easily damaged during the process of tightening and squeezing the sealing ring 8; if the strength of the sealing ring 8 is greater than that of the pressing cap 7, the sealing ring 8 cannot be compressed to generate the corresponding friction force, so the strength requirement of the pressing cap 7 is the same as that of the sealing ring 8, so the pressing cap 7 and the sealing ring 8 are made of the same material.

[0025] It should be noted that in the present embodiment, the material of the pressure cap 7 and the sealing ring 8 is polytetrafluoroethylene, and the material of the traditional sealing ring is usually rubber. Although rubber can maintain good sealing, it is soft and cannot provide sufficiently large friction. After calculations and multiple experiments, the material of the sealing ring 8 is selected as polytetrafluoroethylene. Although its sealing is not as good as traditional rubber, it has met the sealing requirements of the present device. In addition, polytetrafluoroethylene has sufficient strength and can provide sufficient friction after extrusion. Combined with economic reasons, it was finally determined to select polytetrafluoroethylene as the material of the sealing ring 8 and the pressure cap 7 in the present device.

[0026] Furthermore, without considering the economic efficiency, the materials of the sealing ring 8 and the pressure cap 7 can be replaced with other higher quality materials that meet the process conditions.

[0027] In the present invention, a force-bearing plate 9 is provided below the plunger body 6. During the upward stroke of the well pumping unit, the force-bearing plate 9 receives thrust from the liquid below and transmits the thrust to the plunger body 6. When the downhole pressure is small, the thrust received by the force-bearing plate 9 is reduced, and the upward movement distance of the plunger body 6 is reduced. At this time, the flow area between the flow hole and the water outlet hole 4 is increased, and the amount of water injected by the device to the target layer remains unchanged; when the downhole pressure is large, the upward thrust received by the force-bearing plate 9 is large, and the distance the plunger body 6 moves upward is large. At this time, the flow area between the flow hole and the water outlet hole 4 is reduced, and the amount of water injected by the device to the target layer remains unchanged. In actual application, the degree of change of the position of the piston body 6 with pressure during operation is changed by calculating and selecting force-bearing plates 9 of different areas, thereby changing the constant water injection amount of the device.

[0028] Among them, the force-bearing plate 9 is made of ceramic material. By providing a plunger cap 10 under the plunger body 6, the force-bearing plate 9 is installed on the plunger cap 10 and then the plunger cap 10 is threadedly connected to the plunger body 6. This allows for a more stable and convenient installation of the force-bearing plate 9, thereby improving the stability of the device during operation.

[0029] like Figure 1 As shown, a radially opened pressure transmission hole 3 is provided above the device body 2, and the pressure transmission hole 3 is located above the plunger body 6. When the uphole pumping unit enters the downstroke, the pressure transmission hole 3 releases the pressure between the device body 2 and the plunger body 6 in the device, preventing the excessive pressure in the device from pushing the plunger body 6 to move downward, further ensuring the stability of the 'self-locking' state of the device during operation, improving the practicability of the device and extending the service life of the device.

[0030] The constant flow water injection tool for the same well injection and production well provided by the present invention can quantitatively replenish water to the target formation for a long time in the same well injection and production well, has a relatively long service life, and meets the technical requirements of the same well injection and production well for long-term quantitative water replenishment of the formation. The specific operation process of the device is as follows: First, the device is lowered into the well along with the downhole tool section of the injection and production well during the operation and construction process, and the device is then lowered into the target working position.

[0031] Then, during the operation of the pumping unit, during the upward stroke of the pumping unit, liquid flows into the device from below to impact the force-bearing plate, pushing the plunger body upward, the liquid outlet holes on the device body and the plunger body reach a pre-designed overlap, and the liquid is injected into the external target formation through the liquid outlet holes.

[0032] Next, the well pumping unit enters the downstroke, at which time the pressure transmission hole relieves the pressure between the device body and the plunger body. At the same time, the friction force generated between the sealing ring compressed by the pressure cap and the device body and the pressure relief effect of the pressure relief hole cooperate to balance the downward elastic force of the plunger spring, and the plunger body remains in position. When entering the next upstroke, since its position has reached the limit position that the thrust can push, the position of the plunger body remains unchanged and always maintains quantitative water injection into the target formation.

[0033] Afterwards, the above process is repeated, and the device always maintains quantitative water injection into the target formation. At the same time, the plunger spring is in a compressed state most of the time, and no repeated action is required, thereby extending the service life of the device.

[0034] During operation, the plunger body sometimes slides downward under the action of pressure from above, but during the next upward stroke, it is pushed to a preset position and fixed by the thrust.

[0035] 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 constant flow water injection tool for a well with injection and production, characterized in that: include: Device body (2), plunger body (6) and screen plug (11); The plunger body (6) is installed in the device body (2), and the bottom of the device body (2) is connected to a screen plug (11); the plunger body (6) is tubular, and the top end is sealed; two flow holes are symmetrically arranged on the side of the plunger body (6), and four liquid outlet holes (4) are evenly arranged on the side of the device body (2); the flow holes correspond to the positions of the liquid outlet holes (4), and after the liquid flows into the plunger body (6) from the bottom, it can flow out of the device body (2) through the flow holes and the liquid outlet holes (4); the top of the plunger body (6) is provided with a plunger spring (1); the side of the device body (2) is provided with a pressure transmission hole (3), and the pressure transmission hole (3) The plunger body (6) is positioned above the plunger body (6) to relieve the pressure between the plunger body (6) and the device body (2) to reduce the downward pressure on the plunger body (6); a sealing ring (8) is provided on the outside of the plunger body (6) above the liquid outlet hole (4); a pressure cap (7) is provided above the sealing ring (8) to squeeze the sealing ring (8) to make it interfere; and the friction force generated by the interfered portion and the device body (2) cooperates with the pressure transmission hole (3) to balance the thrust of the spring after compression; a detachable force-bearing sheet (9) is provided below the plunger body (6); the size of the constant water injection flow rate is adjusted by changing the area of ​​the force-bearing sheet (9).

2. The constant flow water injection tool for injection and production wells according to claim 1, characterized in that: The pressing cap (7) and the sealing ring (8) are made of the same material, both of which are polytetrafluoroethylene.

3. The constant flow water injection tool for injection and production wells according to claim 1, characterized in that: A vertical straightening rod (5) is provided on the top of the plunger body (6), and the plunger spring (1) is sleeved on the straightening rod (5).

4. The constant flow water injection tool for a well for injection and production in the same well according to claim 1, characterized in that: The device body (2) and the screen plug (11) are connected via threads.

5. The constant flow water injection tool for injection and production wells according to claim 1, characterized in that: A plunger cap (10) is provided at the bottom of the plunger body (6), and the force-bearing sheet (9) is installed in the plunger cap (10).

6. The constant flow water injection tool for a well for injection and production in the same well according to claim 1, characterized in that: A plurality of O-type packings (12) are respectively provided on the top of the device body (2) and the bottom of the screen plug (11).

7. The constant flow water injection tool for a well for injection and production in the same well according to claim 1, characterized in that: The pressing cap (7) is connected to the plunger body (6) via threads, and the pressing cap (7) presses the sealing ring (8) by tightening the threads.

8. The constant flow water injection tool for a well for injection and production in the same well according to claim 5, characterized in that: The plunger cap (10) is detachably connected to the plunger body (6).

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