A downhole micro-bubble generator

Abstract

The application belongs to the technical field of oil exploitation equipment, and particularly relates to a downhole micro-bubble generator. The downhole micro-bubble generator comprises an outer cylinder, an inner cylinder and a functional part. A micro-bubble generating part configured to convert gas into micro-bubbles is installed on the side wall of the inner cylinder. The downhole micro-bubble generator according to the application can adapt to the working environment of the downhole, and a large number of micro-bubbles can be generated for plugging and oil displacement operation by using only a physical method. While effectively improving the oilfield recovery rate, the use of chemical reagents such as foaming agents is avoided, which has better economy and good application prospect in the technical field.

Description

Technical Field

[0001] This invention belongs to the field of oil extraction equipment technology, specifically relating to a downhole microbubble generator. Background Technology

[0002] With the continuous expansion of my country's oil production capacity, the reserves of high-quality oilfields are decreasing year by year, while the proportion of low-permeability and ultra-low-permeability reservoirs in recoverable reservoirs is gradually increasing. Low-permeability and ultra-low-permeability reservoirs are characterized by strong formation heterogeneity and susceptibility to reservoir damage. Using CO2 enhanced oil recovery technology is a feasible solution. CO2 flooding technology can improve the utilization and recovery rates of low-permeability reservoirs and also achieve geological CO2 sequestration, contributing to the creation of green enterprises in oilfields.

[0003] Major energy groups have begun construction on carbon peaking and carbon neutrality projects, but the CO2 gas channeling problem exposed in the application of CO2 enhanced oil recovery technology has seriously affected the effectiveness of CO2 enhanced oil recovery and storage.

[0004] As a commonly used method 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 extraction 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 the field has not reached the expected level. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention provides a downhole microbubble generator.

[0006] The downhole microbubble generator includes:

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

[0008] An inner cylinder, disposed inside the outer cylinder, includes a second main body, a second air inlet opened at the upper end of the second main body, a first through hole disposed on the side wall of the second main body, and a microbubble generating part installed on the side wall of the second main body at a position corresponding to the first through hole; and

[0009] The functional part includes a sealing plate sleeved on the outside of the inner cylinder and a base disposed at the bottom of the inner cylinder. The base forms a seal against the lower end of the inner cylinder. Both the sealing plate and the base are configured to make a sealing contact with the inner wall of the outer cylinder, and are capable of axially moving the inner cylinder along the inner wall of the outer cylinder under the action of external force.

[0010] The downhole microbubble generator is configured such that, under the pressure of the gas introduced into the outer cylinder and the inner cylinder, the functional unit drives the inner cylinder to move along the axial direction of the outer cylinder, causing the inner cylinder to slide from a first position located on the upper part of the outer cylinder to a second position located on the lower part of the outer cylinder corresponding to the grid, thereby allowing the microbubbles converted by the gas through the microbubble generator to 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 section includes a microbubble filter and a microbubble generating plate.

[0013] The microbubble filter is configured with two layers, and the microbubble generating plate is disposed between the two layers of microbubble filter.

[0014] The microbubble generating plate includes a third body and microbubble generating holes disposed on the third body.

[0015] The gas is carbon dioxide, which enables the microbubble generator to perform oil displacement operations using carbon dioxide and to store carbon dioxide.

[0016] The base includes a fourth main body that is cylindrical and open at both ends, a sealing ring that is sleeved on the outside of the fourth main body and configured to make a sealing contact with the inner wall of the outer cylinder, a spring disposed inside the fourth main body, and a piston disposed at the upper end of the spring and configured to slide inside the fourth main body, the upper end of the piston being sealed and embedded in a second through hole disposed at the bottom of the inner cylinder.

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

[0018] A limiting hole is provided 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 cylinder is provided above the first air inlet, and a second air inlet connector extending upward from the inner cylinder is provided above the second air inlet.

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

[0021] The advantages of this invention compared to existing technologies are as follows: Through the design of the inner cylinder, outer cylinder, and functional components, the downhole microbubble generator according to this invention can be easily deployed into the well for operation. Furthermore, thanks to the design of the microbubble generating section, gas is converted into microbubbles upon passage, thereby achieving oil displacement and improving oilfield recovery while effectively preventing gas channeling. When the introduced gas is carbon dioxide, it can also be sealed, resulting in good environmental protection. Moreover, the downhole microbubble generator of this invention generates microbubbles through physical foaming, without the use of foaming agents, stabilizers, or other chemical agents, thus reducing extraction costs. The generation of microbubbles also solves the shortcomings of existing technologies, such as large foam size and poor injectability. Attached Figure Description

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

[0023] All the accompanying drawings in this invention are schematic diagrams for illustrating the structure and principle, and are not necessarily drawn according to actual dimensions and proportions.

[0024] The specific meanings of the various labels in the figure are as follows:

[0025] 1. Outer cylinder; 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 cylinder; 21. Second main body; 22. Second air inlet; 23. First through hole; 24. Microbubble generator; 241. Microbubble filter; 242. Microbubble generator plate; 2421. Third main body; 2422. Microbubble generator hole; 25. Second through hole; 26. Second limiting bolt hole; 27. Second air inlet connector; 3. Functional part; 31. Separator plate; 32. Base; 321. Fourth main body; 322. Separator ring; 323. Spring; 324. Piston; 100. Downhole microbubble generator. Detailed Implementation

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

[0027] Figure 1This is a schematic diagram of the downhole microbubble generator 100 according to the present invention. As shown, the downhole microbubble generator 100 according to the present invention includes an outer cylinder 1, an inner cylinder 2, and a functional part 3. The outer cylinder 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 disposed on the lower side wall of the first main body 11. The grids 13 can also be regarded as rectangular through holes opened on the lower side wall of the first main body 11, so that the gas inside the outer cylinder 1 can enter the downhole environment through the grids 13. The inner cylinder 2 is disposed inside the outer cylinder 1 and includes 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 disposed 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 generator 24 is configured to convert gas into microbubbles after gas passes through it. It is installed on the side wall of the second main body 21 at a position corresponding to the first through-hole 23, allowing gas inside the inner cylinder 2 to enter the microbubble generator 24 after passing through the first through-hole 23, or to enter the downhole environment after passing through the microbubble generator 24 and then through the first through-hole 23, thus ensuring smooth gas flow. The functional part 3 includes a sealing plate 31 sleeved on the upper outer side of the inner cylinder 2 and a base 32 disposed at the bottom of the inner cylinder 2. The base 32 provides a sealing function to the lower end of the inner cylinder 2, and both the sealing plate 31 and the base 32 are configured to make a sealing contact with the inner wall of the outer cylinder 1, and can be driven by external force to move the inner cylinder 2 axially along the inner wall of the outer cylinder 1.

[0028] In actual operation, the inner cylinder 2 is fixed at a first position above the inner wall of the outer cylinder 1, and the sealing plate 31 and the base 32 in the functional part 3 are in closed contact with the inner wall of the outer cylinder 1. It should be noted that at this time, the part of the base 32 connected to the lower end of the inner cylinder 2 that is in sealed contact with the inner wall of the outer cylinder 1 is above the grid 13. Therefore, the part above the base 32 is in a sealed state during the gas introduction process. The downhole microbubble generator 100 according to the present invention is connected to the air inlet pipe (not shown, the same below) and lowered into the working part in the well. Then, gas is introduced through an external gas source and the air inlet pipe. The gas enters the outer cylinder 1 through the first air inlet 12 and enters the interior of the inner cylinder 2 through the second air inlet 22. Since the sealing plate 31 and the base 32 in the functional part 3 are both constructed to be in sealed contact with the inner wall of the outer cylinder 1, the gas entering the outer cylinder 1 and the inner cylinder 2 cannot flow to other areas (i.e., it is in a sealed state). As gas is continuously introduced, the gas pressure on the sealing plate 31 and the base 32 continuously increases, and this increasing pressure is transmitted to the inner cylinder 2, causing the inner cylinder 2 to also experience increasing downward pressure. When this pressure exceeds the connecting force between the inner cylinder 2 and the outer cylinder 1, the inner cylinder 2 separates from the outer cylinder 1 and moves downward along the axial direction of the outer cylinder 1 under the action of the functional unit 3 until the base 32 contacts the bottom of the outer cylinder 1. At this time, the inner cylinder 2 is in the second position corresponding to the grid 13 provided on the lower side wall of the outer cylinder 1, that is, the working position of the inner cylinder 2. Since the first through hole 23 and the microbubble generator 24 are provided on the side wall of the inner cylinder 2, the gas inside the inner cylinder 2 is converted into microbubbles after passing through the microbubble generator 24 and enters the downhole environment. A large number of microbubbles form a foam-like structure, which can, on the one hand, block the downhole channels and effectively prevent gas leakage; on the other hand, these microbubbles also have an oil displacement effect, thus helping to improve the oilfield's recovery rate.

[0029] The downhole microbubble generator 100 of the present invention, through the design of the outer cylinder 1, inner cylinder 2, and functional part 3, allows for easy deployment into the well for operation. Furthermore, thanks to the design of the microbubble generating part 24, gas is converted into microbubbles upon passing through, thereby achieving oil displacement and improving oilfield recovery while effectively preventing gas channeling. Moreover, the downhole microbubble generator 100 of the present invention generates microbubbles through physical foaming, without the use of foaming agents, stabilizers, or other chemical agents, thus reducing extraction costs. In addition, the generation of microbubbles also overcomes the shortcomings of existing technologies, such as large foam size and poor injectability.

[0030] like Figure 1As shown, in one embodiment of the present invention, the grid 13 is uniformly distributed along the sidewall of the outer cylinder 1 in the circumferential direction. This design enables the microbubbles to have uniform outlet channels, which is beneficial for 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 plate 242. The microbubble filter 242 prevents large particles from entering the interior of the microbubble generating plate 242, thus providing a certain degree of protection for the microbubble generating unit 24. The microbubble generating plate 242 converts gas into microbubbles, which facilitates subsequent oil displacement and plugging operations. Furthermore, the microbubble generating plate 242 generates microbubbles through physical foaming, thereby avoiding the use of chemical agents such as foaming agents and stabilizers, reducing oilfield extraction costs, and improving the economic viability of extraction.

[0032] Furthermore, in one embodiment of the present invention, the microbubble filter 241 is configured as two layers, and the microbubble generating plate 242 is disposed between the two layers of microbubble filter 241. This design ensures that large particles inside the inner cylinder 2 and in the downhole environment are blocked from entering the interior of the microbubble generating plate 242, thereby providing more comprehensive protection for the microbubble generating section 24.

[0033] like Figure 1 As shown, in one embodiment of the present invention, the microbubble generator 24 is disposed outside the first through hole 23. This design facilitates the installation of the microbubble generator 24 and reduces the labor intensity of the workers.

[0034] like Figure 1 As shown, in one embodiment of the present invention, the first through holes 23 are evenly distributed circumferentially on the sidewall of the inner cylinder 2. This design allows microbubbles to flow into the downhole environment along the entire circumference of the sidewall of the inner cylinder 2, thereby expanding the working area of ​​the downhole microbubble generator 100 according to the present invention, which is beneficial for comprehensive oil displacement and sealing of the downhole environment.

[0035] like Figure 1 As shown, in one embodiment of the present invention, the microbubble generating plate 242 includes a third body 2421 and a plurality of microbubble generating holes 2422 disposed on the third body 2421. This design enables the microbubble generating plate 242 to efficiently convert passing gas into microbubbles, thereby facilitating subsequent oil displacement and sealing operations.

[0036] In one embodiment of the present invention, the microbubble generator 24 is configured to generate bubbles with a diameter of less than 50 μm. This design results in smaller bubbles generated by the downhole microbubble generator 100 according to the present invention, making them less prone to aggregation. This facilitates oil displacement while also promoting the formation of foam-like plugging material, thereby solving the gas channeling problem. Furthermore, the small bubble diameter allows for a larger diffusion area within the reservoir, further improving oilfield recovery.

[0037] In one embodiment of the invention, the gas introduced into the downhole microbubble generator 100 according to the invention is carbon dioxide. This design enables the use of carbon dioxide for oil displacement operations and also allows for the storage of carbon dioxide using the microbubble generator 100. This improves oilfield recovery rates and promotes the creation of green enterprises in oilfields, resulting in significant environmental benefits.

[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 a cylindrical structure with openings at both ends. The sealing ring 322 is sleeved on the outside of the fourth body 321 and makes a sealing contact with the inner wall of the outer cylinder 1. The spring 323 is disposed inside the fourth body 321. A piston 324 is disposed at the upper end of the spring 323. The piston 324 is configured to compress the spring 323 under the action of external force, thereby causing axial sliding inside the fourth body 321. 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 achieves a sealing contact with the inner wall of the outer cylinder 1, realizing the sealing effect on the inner cylinder 2 when it is in the first position. On the other hand, it also functions as a pressure relief valve. Specifically, after the microbubble generator 24 has been in use for a period of time, the microbubble filter 241 is highly likely to become clogged due to the continuous impact of large particles in the downhole environment, thus preventing the gas entering the inner cylinder 2 from being discharged in time. The gas pressure inside the inner cylinder 2 gradually increases. When the gas pressure increases to a certain level, the piston 324 is compressed and compresses the spring 323, causing it to descend along the inner wall of the fourth body 321. When the descending distance is long enough, a gap is created between the piston 324 and the second through hole 25. The gas is discharged from the inner cylinder 2 through the gap between the piston 324 and the second through hole 25, and then discharged from the downhole microbubble generator 100 according to the present invention through the grid 13 of the outer cylinder 1 or other channels connected to the downhole environment. This design allows the downhole microbubble generator 100 according to the present invention to be depressurized through the base 32 when it fails, thereby avoiding excessive gas pressure inside the inner cylinder 2 and improving safety during the production process.

[0039] Furthermore, such as Figure 1 As shown, in one embodiment of the present invention, the second through hole 25 is configured as a stepped hole with a small upper inner diameter and a large lower inner diameter. Correspondingly, the piston 324 is constructed as a stepped shaft with a small upper outer diameter and a large lower outer diameter, adapted to the shape of the second through hole 25. This design allows the piston 324 to receive both an upward supporting force from the spring 323 and a downward force from the bottom of the inner cylinder 2 during normal operation. This provides a limiting effect on the piston 324, preventing the seal between the piston 324 and the second through hole 25 from failing due to the continuous force of the spring 323. This improves the stability of the downhole microbubble generator 100 structure according to the present invention.

[0040] In one embodiment of the present invention (not shown), the bottom of the outer cylinder 1 is a closed structure for ease 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, with a limiting hole 14 provided at the bottom of the outer cylinder 1, and the inner diameter of the limiting hole 14 being larger than the outer diameter of the fourth main body 321. This design ensures that when the inner cylinder 2 is in the second position, the base 32 is supported and limited by the bottom of the outer cylinder 1, thereby guaranteeing that the inner cylinder 2 is in a stable working state. Furthermore, when 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, facilitating gas discharge during the depressurization phase.

[0042] like Figure 1 As shown, in one embodiment of the present invention, a first air inlet connector 15 extending upward from the outer cylinder 1 is provided above the first air inlet 12, and a second air inlet connector 27 extending upward from the inner cylinder 2 is provided above the second air inlet 22. In actual operation, the air inlet pipe is connected to the first air inlet connector 15, and gas enters the outer cylinder 1 through the first air inlet connector 15 and enters the inner cylinder 2 through the second air inlet connector 27. This design facilitates the connection and air intake between the air inlet pipe and the downhole microbubble generator 100 according to the present invention when gas is introduced into the well microbubble generator 100 according to the present invention through the air inlet pipe, thereby facilitating precise gas delivery and improving the ease of operation for workers.

[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 intake connector 15, and a second limiting bolt hole 26 is provided on the side wall of the second air intake connector 27. 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 a first position inside the outer cylinder 1. This design makes the connection between the inner cylinder 2 and the outer cylinder 1 more secure and controllable, facilitating subsequent operations.

[0044] The downhole microbubble generator 100 of the present invention, through the design of the outer cylinder 1, inner cylinder 2, and functional part 3, allows for easy deployment into the well for operation. Furthermore, thanks to the design of the microbubble generating part 24, gas can be converted into microbubbles, thereby achieving oil displacement and improving oilfield recovery while effectively preventing gas channeling. When the introduced gas is carbon dioxide, carbon dioxide can also be trapped, resulting in good environmental protection. Moreover, the downhole microbubble generator 100 of the present invention generates microbubbles through physical foaming, without the use of foaming agents, stabilizers, or other chemical agents, thus reducing extraction costs. In addition, the generation of microbubbles also solves the shortcomings of existing technologies, such as large foam size and poor injectability.

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

[0046] Finally, it should be noted that although the present invention has been described in detail with reference to preferred embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, as long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any way. 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) includes 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) provided on the lower side wall of the first main body (11). The inner cylinder (2), disposed inside the outer cylinder (1), includes a second main body (21), a second air inlet (22) opened at the upper end of the second main body (21), a first through hole (23) disposed 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) at a position corresponding to the first through hole (23); and The functional part (3) includes a sealing plate (31) sleeved on the outside of the inner cylinder (2) and a base (32) disposed at the bottom of the inner cylinder (2). The base (32) forms a seal on the lower end of the inner cylinder (2). Both the sealing plate (31) and the base (32) are configured to make a sealing contact with the inner wall of the outer cylinder (1), and can drive the inner cylinder (2) to move axially along the inner wall of the outer cylinder (1) under the action of external force. Gas enters the interior of the outer cylinder (1) through the first air inlet (12) and enters the interior of the inner cylinder (2) through the second air inlet (22). The downhole microbubble generator is configured such that, under the action of the gas pressure generated by the gas introduced into the outer cylinder (1) and the inner cylinder (2), the functional part (3) drives the inner cylinder (2) to move along the axial direction of the outer cylinder (1), so that the inner cylinder (2) slides from the first position located on the upper part of the outer cylinder (1) to the second position located on the lower part of the outer cylinder (1) corresponding to the grid (13), thereby allowing the microbubbles converted by the gas through the microbubble generator (24) to enter the downhole environment through the grid (13).

2. The microbubble generator according to claim 1, characterized in that: The microbubble generating unit (24) includes a microbubble filter (241) and a microbubble generating plate (242).

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

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

5. The microbubble generator according to claim 1, characterized in that: The gas is carbon dioxide, which enables the microbubble generator to perform oil displacement operations using carbon dioxide and to store 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) that is cylindrical and open at both ends, a sealing ring (322) that is sleeved on the outside of the fourth body (321) and configured to seal against the inner wall of the outer cylinder (1), a spring (323) disposed inside the fourth body (321), and a piston (324) disposed at the upper end of the spring (323) and configured to slide inside the fourth body (321). The upper end of the piston (324) is sealed and embedded in a second through hole (25) disposed at the bottom of the inner cylinder (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 upper inner diameter and a large lower inner diameter, and the piston (324) is constructed 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 larger 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 cylinder (1) is provided above the first air inlet (12), and a second air inlet connector (27) extending upward from the inner cylinder (2) is provided above the second air inlet (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 inlet 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 inlet connector (27). 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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