Underground microbubble generator

Abstract

The invention belongs to the technical field of oil exploitation equipment, and particularly relates to an underground microbubble generator. The underground microbubble generator comprises an outer cylinder, an inner cylinder and a functional part. A micro-bubble generating part capable of converting gas into micro-bubbles is mounted on the side wall of the inner cylinder. The underground microbubble generator can adapt to the underground working environment, and a large number of microbubbles can be generated only through a physical method and used for plugging and oil displacement operation. The oil field recovery efficiency is effectively improved, meanwhile, the use of chemical reagents such as foaming agents is avoided, and the method has better economical efficiency and has good application prospects in the technical field.

Description

Technical Field

[0001] The invention belongs to the technical field of oil production equipment, and in particular relates to a downhole microbubble generator. Background Art

[0002] With the continuous expansion of my country's oil production capacity, the reserves of high-quality oil fields are decreasing year by year, and the proportion of low-permeability and ultra-low-permeability reservoirs in recoverable reservoirs is gradually increasing. Low-permeability and ultra-low-permeability reservoirs have the characteristics of strong formation heterogeneity and easy damage to the reservoir. The use of CO2 enhanced oil recovery technology is a more feasible response method. CO2 flooding technology can not only improve the utilization rate and recovery rate of low-permeability reservoirs, but also realize the geological storage of CO2, helping to create green enterprises for oil fields.

[0003] The major energy groups' carbon peak and carbon neutrality projects have begun construction one after another, but the CO2 gas breakthrough problem exposed in the application of CO2 oil recovery technology has seriously affected the effects of CO2 oil recovery and storage.

[0004] As a commonly used means of tertiary oil recovery, foam flooding was first used abroad to prevent gas channeling during gas injection. However, CO2 foam flooding requires foaming agents and auxiliary stabilizers, which increases the mining cost. It also has disadvantages such as excessive foam and poor injectability. These factors have led to the fact that the effect of foam flooding in preventing gas channeling in mines has not reached the expected level. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a downhole microbubble generator.

[0006] The downhole microbubble generator comprises:

[0007] The outer cylinder comprises a first main body, a first air inlet opened at the upper end of the first main body, and a grid arranged on the side wall of the lower part of the first main body;

[0008] an inner cylinder, arranged inside the outer cylinder, comprising a second body, a second air inlet opened at the upper end of the second body, a first through hole arranged on the side wall of the second body, and a microbubble generating portion installed on the side wall of the second body at a position corresponding to the first through hole; and

[0009] The functional part includes a sealing plate sleeved on the outer side of the inner tube and a base arranged at the bottom of the inner tube, wherein the base forms a seal with the lower end of the inner tube, and the sealing plate and the base are both configured to be in sealing contact with the inner wall of the outer tube, and can drive the inner tube to move axially along the inner wall of the outer tube under the action of an external force.

[0010] Wherein, the downhole microbubble generator is constructed such that under the action of the air pressure generated by the gas entering the outer tube and the inner tube, the functional part drives the inner tube to move along the axial direction of the outer tube, so that the inner tube slides from a first position located at the upper part of the outer tube to a second position located at the lower part of the outer tube corresponding to the grid, so that the microbubbles converted by the gas through the microbubble generator enter the downhole environment through the grid.

[0011] As an extension of the above technical solution, the present invention also provides the following embodiments:

[0012] The microbubble generating part includes a microbubble filter and a microbubble generating sheet.

[0013] The microbubble filter is arranged in two layers, and the microbubble generating sheet is arranged between the two layers of microbubble filter.

[0014] The microbubble generating sheet includes a third body and microbubble generating holes arranged on the third body.

[0015] The gas is carbon dioxide, so that the microbubble generator can realize the function of utilizing carbon dioxide for oil displacement and sealing carbon dioxide.

[0016] The base includes a fourth body which is cylindrical and open at both ends, a sealing ring which is sleeved on the outside of the fourth body and is configured to be in sealing contact with the inner wall of the outer tube, a spring arranged inside the fourth body, and a piston which is arranged at the upper end of the spring and is configured to be able to slide inside the fourth body, and the upper end of the piston is sealingly embedded in a second through hole arranged at the bottom of the inner tube.

[0017] The second through hole is configured as a stepped hole with a small inner diameter at the upper portion and a large inner diameter at the lower portion, and the piston is configured as a stepped shaft adapted to the shape of the second through hole.

[0018] A limiting hole is arranged at the bottom of the outer cylinder, and the inner diameter of the limiting hole is larger than the outer diameter of the fourth body.

[0019] A first air inlet connector extending upward from the outer tube is arranged above the first air inlet, and a second air inlet connector extending upward from the inner tube is arranged above the second air inlet.

[0020] A first limiting bolt hole is arranged on the side wall of the first air intake connector, and a second limiting bolt hole corresponding to the first limiting bolt hole is arranged on the side wall of the second air intake connector. The inner cylinder can be fixed at the first position inside the outer cylinder by screwing the limiting bolt into the first limiting bolt hole and the second limiting bolt hole.

[0021] The advantages of the present invention over the prior art are: through the design of the inner tube, the outer tube and the functional part, on the one hand, the downhole microbubble generator according to the present invention can be easily put into the well for operation. On the other hand, thanks to the design of the microbubble generating part, the gas can be converted into microbubbles after passing through, so that the oil displacement effect and the oil field recovery rate can be achieved while effectively preventing the occurrence of gas channeling. When the gas introduced is carbon dioxide, the sealing of carbon dioxide can also be achieved, which has a good environmental protection effect. In addition, the way the downhole microbubble generator according to the present invention generates microbubbles is physical bubbling, and chemical agents such as foaming agents and stabilizers are not used, thereby reducing the mining cost, and the generation of microbubbles also solves the shortcomings of large foam and poor injectability in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic structural diagram of a downhole microbubble generator according to the present invention.

[0023] All drawings in the present invention are schematic diagrams for illustrating structures and principles, and are not necessarily drawn according to actual sizes and proportions.

[0024] The specific meanings of the reference numerals in the figures are as follows:

[0025] 1. Outer tube; 11. First main body; 12. First air inlet; 13. Grid; 14. Limiting hole; 15. First air inlet connector; 16. First limiting bolt hole; 2. Inner tube; 21. Second main body; 22. Second air inlet; 23. First through hole; 24. Microbubble generating part; 241. Microbubble filter; 242. Microbubble generating sheet; 2421. Third main body; 2422. Microbubble generating hole; 25. Second through hole; 3. Functional part; 31. Sealing plate; 32. Base; 321. Fourth main body; 322. Sealing ring; 323. Spring; 324. Piston; 100. Downhole microbubble generator. DETAILED DESCRIPTION

[0026] The embodiments of the present invention will be described in more detail below with reference to the accompanying drawings.

[0027] Figure 1It is a schematic diagram of the structure of the downhole microbubble generator 100 according to the present invention. As shown in the figure, the downhole microbubble generator 100 according to the present invention includes an outer tube 1, an inner tube 2 and a functional part 3. The outer tube 1 includes a first main body 1, a first air inlet 12 opened at the upper end of the first main body 1, and a plurality of grids 13 arranged on the lower side wall of the first main body 11. The grid 13 can also be regarded as a rectangular through hole opened on the lower side wall of the first main body 11, so that the gas inside the outer tube 1 can enter the downhole environment through the grid 13. The inner tube 2 is arranged inside the outer tube 1, including a second main body 21, a second air inlet 22 opened at the upper end of the second main body 21, a plurality of first through holes 23 arranged on the side wall of the second main body 21, and a microbubble generating part 24 installed on the side wall of the second main body 21. The microbubble generating part 24 is configured to convert the gas into microbubbles after the gas passes through, and is installed at a position on the side wall of the second main body 21 corresponding to the first through hole 23, so that the gas inside the inner tube 2 can enter the microbubble generating part 24 after passing through the first through hole 23, or can enter the downhole environment through the first through hole 23 after passing through the microbubble generating part 24, thereby ensuring the smoothness of gas flow. The functional part 3 includes a baffle plate 31 sleeved on the outer side of the upper part of the inner tube 2 and a base 32 arranged at the bottom of the inner tube 2. The base 32 has a sealing effect on the lower end of the inner tube 2, and the baffle plate 31 and the base 32 are both configured to be in sealed contact with the inner wall of the outer tube 1, and can drive the inner tube 2 to move axially along the inner wall of the outer tube 1 under the action of external force.

[0028] During the specific operation, the inner tube 2 is fixed at the first position above the inner part of the outer tube 1, and the baffle plate 31 and the base 32 in the functional part 3 are in closed contact with the inner wall of the outer tube 1. It should be noted that at this time, the base 32 connected to the lower end of the inner tube 2 is in sealed contact with the inner wall of the outer tube 1, so at this time, the part above the base 32 is in a sealed state during the process of passing gas. The downhole microbubble generator 100 according to the present invention is connected to the air intake pipe (not shown, the same below) and lowered into the working part in the well. Afterwards, the gas is introduced through the external gas source and the air intake pipe, and the gas enters the outer tube 1 through the first air inlet 12 and enters the interior of the inner tube 2 through the second air inlet 22. Since the baffle plate 31 and the base 32 in the functional part 2 are both constructed to be in sealed contact with the inner wall of the outer tube 1, the gas entering the outer tube 1 and the inner tube 2 cannot flow to other areas (i.e., in a sealed state). As the gas is continuously introduced, the gas pressure on the baffle plate 31 and the base 32 is continuously increased, and the increasing pressure is transmitted to the inner tube 1, so that the inner tube 1 is also subjected to the increasing downward pressure. When the pressure is greater than the connection force between the inner tube 2 and the outer tube 1, the inner tube 2 is separated from the outer tube 1, and moves downward along the axial direction of the outer tube 1 under the action of the functional part 3 until the base 32 contacts the bottom of the outer tube 1. At this time, the inner tube 2 is in the second position corresponding to the grid 13 arranged on the lower side wall of the outer tube 1, that is, the working position of the inner tube 2. Since the first through hole 23 and the microbubble generating part 24 are arranged on the side wall of the inner tube 2, the gas inside the inner tube 2 is converted into microbubbles after passing through the microbubble generator 24 and enters the underground environment. A large number of microbubbles will form a foam-like organizational structure, which can, on the one hand, seal the large underground channels and effectively prevent the occurrence of gas channeling. On the other hand, these microbubbles also have the effect of oil displacement, which is beneficial to improve the recovery rate of the oil field.

[0029] According to the downhole microbubble generator 100 of the present invention, through the design of the inner tube 1, the outer tube 2 and the functional part 3, on the one hand, it can be easily put into the well for operation. On the other hand, thanks to the design of the microbubble generating part 24, the gas can be converted into microbubbles after passing through, so that it can achieve the oil displacement effect and improve the oil field recovery rate while effectively preventing the occurrence of gas channeling. In addition, the way of generating microbubbles by the downhole microbubble generator 100 of the present invention is physical bubbling, without using chemical agents such as foaming agents and stabilizers, thereby reducing the mining cost. In addition, the generation of microbubbles also solves the shortcomings of large foam and poor injectability in the prior art.

[0030] like Figure 1As shown, in one embodiment of the present invention, the grids 13 are evenly distributed along the side wall of the outer tube 1 in the circumferential direction. Through this design, the microbubbles can have a uniform outlet channel, which is conducive to achieving all-round oil displacement and plugging of the downhole environment.

[0031] like Figure 1 As shown, in one embodiment of the present invention, the microbubble generating unit 24 includes a microbubble filter 241 and a microbubble generating sheet 242. The microbubble filter 242 has the function of preventing large particles from entering the interior of the microbubble generating sheet 242, and has a certain protective effect on the microbubble generating unit 24 as a whole. The function of the microbubble generating sheet 242 is to convert gas into microbubbles to facilitate subsequent oil displacement and plugging operations. And the microbubble generating sheet 242 generates microbubbles in a physical foaming manner, thereby avoiding the use of chemical agents such as foaming agents and stabilizers, reducing the cost of oil field exploitation, and providing the economy of exploitation.

[0032] Furthermore, in one embodiment of the present invention, the microbubble filter 241 is provided with two layers, and the microbubble generating sheet 242 is provided between the two layers of the microbubble filter 241. With this design, large particles inside the inner tube 2 and in the downhole environment can be blocked and will not enter the inside of the microbubble generating sheet 242, so that the protection of the microbubble generating part 24 is more comprehensive.

[0033] like Figure 1 As shown, in one embodiment of the present invention, the micro-bubble generating part 24 is arranged outside the first through hole 23. This design facilitates the installation of the micro-bubble generating part 24 and reduces the labor intensity of the staff.

[0034] like Figure 1 As shown, in one embodiment of the present invention, the first through holes 23 are evenly distributed along the circumferential direction on the side wall of the inner cylinder 2. Through this design, the microbubbles can flow into the downhole environment along the entire circumference of the side wall of the inner cylinder 2, so that the working area of ​​the downhole microbubble generator 100 according to the present invention is wider, which is conducive to comprehensive oil displacement and plugging of the downhole environment.

[0035] like Figure 1 As shown, in one embodiment of the present invention, the microbubble generating sheet 242 includes a third body 2421 and a plurality of microbubble generating holes 2422 disposed on the third body 2421. Through this design, the microbubble generating sheet 242 can efficiently convert the passing gas into microbubbles, which is beneficial to the subsequent oil displacement and plugging operations.

[0036] In one embodiment of the present invention, the microbubble generating unit 24 is configured to generate bubbles with a diameter less than 50 μm. Through this design, the bubbles generated by the downhole microbubble generator 100 according to the present invention are smaller in size and less likely to aggregate. While being able to achieve an oil displacement effect, it is easier to form a foam-like plugging object, thereby solving the gas channeling problem. In addition, due to the small bubble diameter, the area in which the bubbles can diffuse in the oil reservoir is larger, further improving the recovery rate of the oil field.

[0037] In one embodiment of the present invention, the gas introduced into the downhole microbubble generator 100 according to the present invention is carbon dioxide. Through this design, the microbubble generator 100 according to the present invention can realize the oil recovery operation using carbon dioxide, and can realize the sealing function of carbon dioxide. While improving the oil field recovery rate, it also promotes the creation of green enterprises in the oil field, and has a good environmental protection effect.

[0038] like Figure 1 As shown, in one embodiment of the present invention, the base 32 includes a fourth body 321, a sealing ring 322, a spring 323 and a piston 324. The fourth body 321 is configured as a cylinder with two ends open, the sealing ring 322 is configured to be sleeved on the outside of the fourth body 321 and in sealing contact with the inner wall of the outer cylinder 1, the spring 323 is arranged inside the fourth body 321, and a piston 324 is arranged at the upper end of the spring 323. The piston 324 is configured to be able to compress the spring 323 under the action of an external force so as to cause axial sliding inside the fourth body 321, and the upper end of the piston 324 is sealed and embedded in the second through hole 25 at the bottom of the inner cylinder 2. Through this design, on the one hand, the base 32 is configured to be in sealing contact with the inner wall of the outer cylinder 1, and the sealing effect on the inner cylinder 2 is achieved when the inner cylinder 2 is in the first position. On the other hand, it also plays the role of a pressure relief valve. Specifically, after the microbubble generating part 24 has been used for a period of time, the microbubble filter 241 is constantly impacted by large particles in the downhole environment, and there is a high probability that it will be blocked, so that the gas entering the inner cylinder 2 cannot be discharged from the inner cylinder 2 in time. The air pressure inside the inner cylinder 2 gradually increases. When the air pressure increases to a certain extent, the piston 324 is compressed and compresses the spring 323 to move downward along the inner wall of the fourth body 321. When the downward distance is long enough, a gap will be generated between the piston 323 and the second through hole 25, and the gas will be discharged from the inner cylinder 2 through the gap between the piston 323 and the second through hole 25, and then through the grid 13 of the outer cylinder 1 or other channels connected to the downhole environment and discharged from the downhole microbubble generator 100 according to the present invention. Through this design, when the downhole microbubble generator 100 according to the present invention is in the failure stage, it can be depressurized through the base 32, thereby avoiding excessive air pressure inside the inner cylinder 2 and improving the safety during the production process.

[0039] Furthermore, if Figure 1 As shown, in one embodiment of the present invention, the second through hole 25 is set as a stepped hole with a small inner diameter at the upper part and a large inner diameter at the lower part. Correspondingly, the piston 324 is constructed as a stepped shaft with a small outer diameter at the upper part and a large outer diameter at the lower part adapted to the shape of the second through hole 25. Through this design, in the normal working stage, the piston 324 can be subjected to a downward force at the bottom of the inner cylinder 2 while being subjected to an upward supporting force of the spring 323. Thereby, a limiting effect is formed on the piston 324, so that the seal between the piston 324 and the second through hole 25 is not easy to fail due to the continuous effect of the elastic force of the spring 323. Thereby, the stability of the structure of the downhole microbubble generator 100 according to the present invention is improved.

[0040] In an embodiment of the present invention which is not shown, the bottom of the outer cylinder 1 is a closed structure for the convenience of processing and manufacturing.

[0041] like Figure 1 As shown, in one embodiment of the present invention, the bottom of the outer cylinder 1 is constructed as a non-enclosed structure, and a limiting hole 14 is provided at the bottom of the outer cylinder 1, and the inner diameter of the limiting hole 14 is set to be larger than the outer diameter of the fourth body 321. Through this design, when the inner cylinder 2 is in the second position, the base 32 can be supported and limited by the bottom of the outer cylinder 1, thereby ensuring that the inner cylinder 2 is in a stable working state. In addition, when the gas overflows from the gap between the piston 324 and the second through hole 25, it can also be discharged from the outer cylinder 1 through the limiting hole 14, which facilitates the discharge of the gas in the pressure relief stage.

[0042] like Figure 1 As shown, in one embodiment of the present invention, a first air inlet connector 15 extending upward from the outer tube 1 is provided above the first air inlet 12, and a second air inlet connector 25 extending upward from the inner tube 2 is provided above the second air inlet 22. During specific operations, the air inlet pipe is connected to the first air inlet connector 15, and the gas enters the outer tube 1 through the first air inlet connector 15, and enters the inner tube 2 through the second air inlet connector 25. Through this design, when the gas is introduced into the well microbubble generator 100 according to the present invention through the air inlet pipe, the connection and air intake between the air inlet pipe and the downhole microbubble generator 100 according to the present invention are facilitated, thereby facilitating the precise delivery of gas and also facilitating the convenience of operation of the staff.

[0043] like Figure 1As shown, in one embodiment of the present invention, a first limiting bolt hole 16 is provided on the side wall of the first air inlet connector 15, and a second limiting bolt hole 26 is provided on the side wall of the second air inlet connector 25, and the first limiting bolt hole 16 and the second limiting bolt hole 26 are configured to correspond to each other. By screwing the limiting bolt (not shown, the same below) into the first limiting bolt hole 16 and the second limiting bolt hole 26, the inner cylinder 2 can be fixed at the first position inside the outer cylinder 1. Through this design, the connection between the inner cylinder 2 and the outer cylinder 1 is made more firm and controllable, which facilitates the smooth progress of subsequent operations.

[0044] According to the downhole microbubble generator 100 of the present invention, through the design of the inner tube 1, the outer tube 2 and the functional part 3, on the one hand, it can be easily put into the well for operation. On the other hand, thanks to the design of the microbubble generating part 24, the gas can be converted into microbubbles, so that it can achieve the effect of oil displacement and improve the oil field recovery rate while effectively preventing the occurrence of gas channeling. When the gas introduced is carbon dioxide, it is also possible to achieve the sealing of carbon dioxide, which has a good environmental protection effect. In addition, the way of producing microbubbles in the downhole microbubble generator 100 of the present invention is physical bubbling, without using chemical agents such as foaming agents and stabilizers, thereby reducing the cost of mining. In addition, the generation of microbubbles also solves the shortcomings of large foam and poor injectability in the prior art.

[0045] In this application, the specific meanings of the terms "upper", "lower", "inner", "outer", "middle", "side" and the like when indicating directions are as follows: Figure 1 The drawn state of the downhole microbubble generator 100 is used as a reference.

[0046] Finally, it should be noted that although the present invention has been described in detail with reference to the preferred embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present invention. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there is no structural conflict. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A downhole microbubble generator, comprising: The outer cylinder (1) comprises a first main body (11), a first air inlet (12) opened at the upper end of the first main body (11), and a grid (13) arranged on the lower side wall of the first main body (11); The inner cylinder (2) is arranged inside the outer cylinder (1), and comprises a second body (21), a second air inlet (22) opened at the upper end of the second body (21), a first through hole (23) arranged on the side wall of the second body (21), and a micro bubble generating portion (24) installed at a position on the side wall of the second body (21) corresponding to the first through hole (23); and The functional part (3) comprises a sealing plate (31) sleeved on the outside of the inner tube (2) and a base (32) arranged at the bottom of the inner tube (2), wherein the base (32) forms a seal with the lower end of the inner tube (2), and the sealing plate (31) and the base (32) are both configured to be in sealing contact with the inner wall of the outer tube (1), and can drive the inner tube (2) to move axially along the inner wall of the outer tube (1) under the action of an external force. The downhole microbubble generator is configured such that, under the action of the gas pressure generated by the gas entering the outer tube (1) and the inner tube (2), the functional part (3) drives the inner tube (2) to move along the axial direction of the outer tube (1), so that the inner tube (2) slides from a first position located at the upper part of the outer tube (1) to a second position located at the lower part of the outer tube (1) corresponding to the grid (13), so that the microbubbles converted by the gas through the microbubble generator (24) enter the downhole environment through the grid (13).

2. The microbubble generator according to claim 1, characterized in that: The microbubble generating section (24) comprises a microbubble filter (241) and a microbubble generating sheet (242).

3. The microbubble generator according to claim 2, characterized in that: The microbubble filter (241) is provided in two layers, and the microbubble generating sheet (242) is provided between the two layers of the microbubble filter (241).

4. The microbubble generator according to claim 2, characterized in that: The microbubble generating sheet (242) includes a third body (2421) and a microbubble generating hole (2422) disposed on the third body (2421).

5. The microbubble generator according to claim 1, characterized in that: The gas is carbon dioxide, so that the microbubble generator can realize the function of utilizing carbon dioxide for oil displacement and sealing carbon dioxide.

6. The microbubble generator according to any one of claims 1 to 5, characterized in that: The base (32) includes a fourth body (321) which is cylindrical and open at both ends, a sealing ring (322) which is sleeved on the outside of the fourth body (321) and is configured to be in sealing contact with the inner wall of the outer tube (1), a spring (323) arranged inside the fourth body (321), and a piston (324) which is arranged at the upper end of the spring (323) and is configured to be able to slide inside the fourth body (321), and the upper end of the piston (324) is sealingly embedded in a second through hole (25) arranged at the bottom of the inner tube (2).

7. The microbubble generator according to claim 6, characterized in that: The second through hole (25) is configured as a stepped hole with a small inner diameter at the upper portion and a large inner diameter at the lower portion, and the piston (324) is configured as a stepped shaft adapted to the shape of the second through hole (25).

8. The microbubble generator according to claim 6, characterized in that: A limiting hole (14) is provided at the bottom of the outer cylinder (1), and the inner diameter of the limiting hole (14) is greater than the outer diameter of the fourth body (321).

9. The microbubble generator according to claim 1, characterized in that: A first air inlet connector (15) extending upward from the outer tube (1) is arranged above the first air inlet port (12), and a second air inlet connector (25) extending upward from the inner tube (2) is arranged above the second air inlet port (22).

10. The microbubble generator according to claim 9, characterized in that: A first limiting bolt hole (16) is provided on the side wall of the first air intake connector (15), and a second limiting bolt hole (26) corresponding to the first limiting bolt hole (16) is provided on the side wall of the second air intake connector (25). By screwing the limiting bolt into the first limiting bolt hole (16) and the second limiting bolt hole (26), the inner cylinder (2) can be fixed at the first position inside the outer cylinder (1).

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