Self-circulation lifting device and method

Abstract

The invention belongs to the technical field of oil and gas exploitation, and particularly relates to a self-circulation lifting device and method. An oil pipe is arranged in a shaft casing pipe, an annular cavity is formed between the oil pipe and the shaft casing pipe, the self-circulation lifting device comprises a gas-liquid separator, a first compressor and a gas storage tank which are sequentially connected from the upper end of the oil pipe to the upper end of the annular cavity, gas in the gas storage tank is injected into the annular cavity, and the first compressor is connected with the gas-liquid separator. The gas enters the oil pipe to lift the mixed fluid of the gas and the water in the oil pipe, the mixed fluid flows out of the upper end of the oil pipe, the gas is separated out through the gas-liquid separator, the separated gas is stored in the gas storage tank through the first compressor, and circulation is carried out. The gas injection lifting process can be smoothly implemented under the working conditions that a high-pressure gas source cannot be obtained by an exploratory well, a remote well and the like.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas extraction technology, specifically relating to a self-circulating lift device and a self-circulating lift method. Background Technology

[0002] Once a natural gas well produces water, it increases wellbore pressure loss and reduces gas production. To address this issue, the main current approach is to maintain stable production in water-producing gas wells through drainage and gas production technology. However, for wells with high fluid production, drainage and gas production technologies such as bubble drainage and plunger drainage cannot meet the required intensity. In such cases, an external high-pressure gas source, typically natural gas or nitrogen, is needed. This gas is injected through the annular cavity between the tubing and casing, and the fluid accumulated at the bottom of the well is lifted out of the wellhead through the bottom boundary of the tubing, thereby releasing the gas well's production capacity.

[0003] However, exploratory and remote wells often lack access to high-pressure gas sources due to inadequate or incomplete pipeline networks. They typically rely on equipment such as membrane nitrogen generators to inject nitrogen into the wellbore, a method that is costly and cannot achieve continuous injection, significantly reducing its effectiveness. Furthermore, as the energy of a natural gas well deteriorates and enters a low-pressure, low-production phase, some of the injected high-pressure annulus gas will be pumped back into the formation, reducing lift efficiency and further diminishing its effectiveness.

[0004] Therefore, there is an urgent need to develop a lifting device and lifting method that can guarantee the gas supply, ensure the continuity and flexibility of gas injection, and prevent high-pressure gas from being pumped back into the formation. Summary of the Invention

[0005] In view of the technical problems described above, the present invention aims to provide a self-circulating lifting device that can solve at least one of the above problems.

[0006] The present invention also proposes a self-circulating lifting method, which uses the self-circulating lifting device provided according to the present invention, and the method can solve at least one of the above-mentioned problems.

[0007] According to the present invention, a self-circulating lift device is provided, wherein an oil pipe is provided inside a well casing, and an annular cavity is formed between the oil pipe and the well casing. The self-circulating lift device includes a gas-liquid separator, a first compressor, and a gas storage tank connected in sequence from the upper end of the oil pipe to the upper end of the annular cavity.

[0008] The gas in the gas storage tank is injected into the annular cavity, and then enters the oil pipe to lift the gas-water mixture in the oil pipe. The mixture flows out from the upper end of the oil pipe and passes through the gas-liquid separator to separate the gas. The separated gas is then stored in the gas storage tank by the first compressor, and the cycle repeats.

[0009] In a preferred embodiment, a packer is provided in the annular cavity, the packer being located above the downhole perforated section, and a multi-functional working cylinder is provided on the tubing, the multi-functional working cylinder being located above the packer, allowing gas in the annular cavity to enter the tubing through the multi-functional working cylinder.

[0010] In a preferred embodiment, a first check valve is provided between the gas-liquid separator and the first compressor, and a second check valve is provided between the first compressor and the gas storage tank.

[0011] In a preferred embodiment, a second compressor is provided between the gas storage tank and the annular cavity.

[0012] In a preferred embodiment, a third check valve is provided between the gas storage tank and the second compressor, and a fourth check valve is provided between the second compressor and the annular cavity.

[0013] In a preferred embodiment, a first pressure gauge is provided at the upper end of the oil pipe, and a second pressure gauge is provided at the upper end of the annular cavity.

[0014] In a preferred embodiment, the self-circulating lifting device further includes a control mechanism, which is electrically connected to the first pressure gauge via a first sensor, electrically connected to the second pressure gauge via a second sensor, and electrically connected to the first compressor.

[0015] In a preferred embodiment, a flow meter is provided between the gas storage tank and the annular cavity.

[0016] In a preferred embodiment, the self-circulating lifting device further includes a wastewater tank connected to the gas-liquid separator, the wastewater tank being used to receive water separated by the gas-liquid separator.

[0017] According to the present invention, a self-circulating lift method is also provided, which uses the self-circulating lift device provided by the present invention to pressurize the gas produced in the well and reinject it to lift the gas and water mixture in the tubing to achieve continuous gas injection production.

[0018] Compared with the prior art, the advantages of this application are as follows.

[0019] This invention utilizes natural gas produced by the well itself. After being pressurized by a compressor, it is reinjected into the annular space between the well casing and the tubing. The gas then enters the tubing, where a mixture of natural gas and water is lifted. This mixture exits the tubing and undergoes gas-liquid separation in a gas-liquid separator. The separated liquid enters a wastewater tank, while a portion of the separated natural gas is supplied to users, and the remainder is stored in a storage tank. When a lifting process is needed, the stored natural gas is pressurized by a compressor and reinjected into the wellbore, completing one cycle. This invention utilizes the well's own gas source, eliminating the need for an external gas source and broadening the application scope of the process.

[0020] In addition, to enhance the adaptability of the invention and reduce energy consumption, a control mechanism was designed. By collecting pressure data at the upper end of the tubing and the upper end of the annular cavity, the amount of fluid accumulated in the wellbore is automatically calculated. The control system automatically judges the amount of fluid accumulated. When the amount of fluid accumulated is large, the compressor is started to perform lifting operations. When the amount of fluid accumulated is small, the compressor is stopped, achieving the purpose of energy saving and consumption reduction. There is no need for manual judgment of the fluid accumulation in the wellbore, nor is there a need for manual start and stop of the equipment. This improves the flexibility of the system and also enhances the management efficiency and management level of the process.

[0021] Meanwhile, a multi-functional working cylinder and packer are installed in the downhole tubing and annular space. High-pressure gas enters the tubing through the circulation hole on the multi-functional working cylinder and then lifts the fluid upward. The packer separates the high-pressure injected gas from the perforated section of the production formation, preventing the high-pressure gas source from pumping the accumulated gas back into the formation and improving the lifting efficiency. Attached Figure Description

[0022] The invention will now be described with reference to the accompanying drawings.

[0023] Figure 1 A schematic diagram of one embodiment of the self-circulating lifting device according to the present invention is shown;

[0024] Figure 2 A schematic diagram of one embodiment of the multifunctional working cylinder according to the present invention is shown.

[0025] In the diagram: 1. Well casing; 2. Tubing; 3. Perforation section; 4. Packer; 5. Multifunctional working cylinder; 6. First valve; 7. Second valve; 8. Third valve; 9. Fourth valve; 10. First pressure gauge; 11. First sensor; 12. Gas-liquid separator; 13. Wastewater tank; 14. First check valve; 151. First compressor; 152. Second compressor; 16. Gas storage tank; 17. Control mechanism; 18. Third check valve; 19. Second check valve; 20. Flow meter; 21. Fourth check valve; 22. Second sensor; 23. Second pressure gauge; 30. Annular cavity; 51. Circulation hole; 52. Check valve; 100. Self-circulating lifting device.

[0026] In this application, all drawings are schematic and are used only to illustrate the principles of the invention, and are not drawn to scale. Detailed Implementation

[0027] The invention will now be described with reference to the accompanying drawings.

[0028] It should be noted that the directional terms or qualifiers used in this application, such as "upper," "lower," "left," and "right," refer to the accompanying drawings. They are not used to define the absolute position of the components involved, but can vary depending on the specific circumstances.

[0029] Figure 1 The structure of the self-circulating lifting device 100 according to the present invention is shown. For example... Figure 1 As shown, the self-circulating lifting device 100 includes an oil pipe 2 disposed inside the well casing 1. The outer diameter of the oil pipe 2 is smaller than the inner diameter of the well casing 1, thereby forming an annular cavity 30 between the oil pipe 2 and the well casing 1.

[0030] The self-circulating lifting device includes a gas-liquid separator 12, a first compressor 151, and an air tank 16 connected in sequence from the upper end of the oil pipe 2 to the upper end of the annular cavity 30. That is, the upper end of the oil pipe 2, the gas-liquid separator 12, the first compressor 151, the air tank 16, and the upper end of the annular cavity 30 are connected in sequence to form a closed loop.

[0031] In this configuration, when the gas injection lift process is required, the natural gas in the gas storage tank 16 is injected into the annular cavity 30, and then enters the oil pipe 2 to lift the mixture of natural gas and water in the oil pipe 2. The mixture flows out from the upper end of the oil pipe 2 and passes through the gas-liquid separator 12 to separate the natural gas. The separated natural gas is stored in the gas storage tank 16 through the first compressor 151 and circulates repeatedly. Thus, it does not require an external gas source and can achieve self-circulation, which broadens the application range of the gas injection lift process.

[0032] In one specific embodiment, the self-circulating lifting device 100 further includes a sewage tank 13, which is connected to the gas-liquid separator 12 and is used to receive the water separated by the gas-liquid separator 12.

[0033] In a preferred embodiment, a packer 4 is provided within the annular cavity 30, positioned above the downhole perforated section 3. That is, the packer 4 separates the downhole perforated section 3 from the top of the annular cavity 30. After natural gas from the gas storage tank 16 is injected into the annular cavity 30 from the top, it will not affect the perforated section 3, thereby preventing the high-pressure natural gas in the gas storage tank 16 from forcing the natural gas-water mixture in the wellbore back into the formation from the perforated section 3.

[0034] Furthermore, a multi-functional working cylinder 5 is installed on the oil pipe 2. The multi-functional working cylinder 5 is located above the packer 4. The high-pressure natural gas injected into the annular cavity 30 by the gas storage tank 16 can enter the oil pipe 2 through the multi-functional working cylinder 5, and the high-pressure natural gas enters the oil pipe 2 through the multi-functional working cylinder 5 to lift the mixture of natural gas and water.

[0035] In a specific embodiment, such as Figure 2 As shown, the multi-functional working cylinder 5 includes a circulation hole 51 on its outer wall. High-pressure natural gas injected into the annular cavity 30 by the gas storage tank 16 enters the oil pipe 2 through the circulation hole 51.

[0036] The multi-functional working cylinder 5 also includes an internal one-way valve 52 located below the circulation hole 51, which only allows fluid to flow from bottom to top. After the high-pressure natural gas injected into the annular cavity 30 by the gas storage tank 16 enters the oil pipe 2 through the circulation hole 51, the high-pressure natural gas can only lift the natural gas and water mixture upwards because of the one-way valve below the circulation hole 51, thus preventing the high-pressure natural gas from flowing downwards and forcing the natural gas and water mixture back into the formation from the perforation section 3.

[0037] According to a preferred embodiment of the present invention, a first check valve 14 is provided between the gas-liquid separator 12 and the first compressor 151, and a second check valve 19 is provided between the first compressor 151 and the gas storage tank 16. The first check valve 14 and the second check valve 19 only allow fluid to flow from the upper end of the oil pipe 2 toward the gas storage tank 16.

[0038] In a preferred embodiment of the present invention, a second compressor 152 is provided between the gas storage tank 16 and the annular cavity 30. The second compressor 152 can further increase the pressure of the natural gas injected into the annular cavity 30, thereby enhancing the lifting effect.

[0039] Furthermore, a third check valve 18 is provided between the gas storage tank 16 and the second compressor 152, and a fourth check valve 21 is provided between the second compressor 152 and the annular cavity 30. The third check valve 18 and the fourth check valve 21 only allow natural gas to move from the gas storage tank 16 to the annular cavity 30.

[0040] In a preferred embodiment of the present invention, a first pressure gauge 10 is provided at the upper end of the tubing 2, and a second pressure gauge 23 is provided at the upper end of the annular cavity 30. The pressure at the upper end of the tubing 2 and the pressure at the upper end of the annular cavity 30 are measured by the first pressure gauge 10 and the second pressure gauge 23 respectively, and the amount of downhole fluid (a mixture of natural gas and water) is calculated accordingly to determine whether it is necessary to start the first compressor 151 and the second compressor 152 to implement the gas injection lift process.

[0041] Furthermore, the self-circulating lifting device 100 provided according to the present invention also includes a control mechanism 17, which is electrically connected to a first pressure gauge 10 via a first sensor 11, electrically connected to a second pressure gauge 23 via a second sensor 22, and electrically connected to a first compressor 151 and a second compressor 152.

[0042] By setting up the control mechanism 17, automatic acquisition of the pressure at the upper end of the tubing 2 and the pressure at the upper end of the annular cavity 30 can be achieved. The first pressure gauge 10 transmits the pressure data at the upper end of the tubing 2 to the control mechanism 17 through the first sensor 11, and the second pressure gauge 23 transmits the pressure data at the upper end of the annular cavity 30 to the control mechanism 17 through the second sensor 22. The control mechanism 17 then uses these pressure data to calculate the amount of downhole fluid and automatically determines whether it is necessary to start the first compressor 151 and the second compressor 152 to implement the gas injection lifting process.

[0043] In this invention, the formula for calculating the amount of downhole fluid is as follows:

[0044] W = 3.14 × 10 -6 ×d 2 ×(Pc-Pt) / 4ρg

[0045] In the formula: d - inner diameter of oil pipe 2, mm;

[0046] Pc - Pressure inside the casing (annular cavity 30), MPa;

[0047] Pt - Pressure inside oil pipe 2, MPa;

[0048] ρ - Liquid density, kg / m³ 3 ;

[0049] g - gravitational acceleration, 9.8 m / s² 2 .

[0050] According to the different energy stages of the gas well, the corresponding threshold for the amount of downhole liquid is set. When the amount of downhole liquid exceeds the set threshold, the control mechanism 17 turns on the first compressor 151 and the second compressor 152 to implement the gas injection lifting process. When the amount of downhole liquid does not exceed the set threshold, the control mechanism 17 turns off the first compressor 151 and the second compressor 152.

[0051] In one specific embodiment, the control mechanism 17 is a PLC control cabinet.

[0052] According to the present invention, a flow meter 20 is provided between the gas storage tank 16 and the annular cavity 30 to measure the flow rate of natural gas injected into the annular cavity 30. Further, the flow meter 20 is disposed between the second compressor 152 and the fourth check valve 21.

[0053] In a specific embodiment provided by the present invention, a third valve 8 is provided at the upper end of the annular cavity 30. After the natural gas in the gas storage tank 16 is pressurized by the second compressor 152, it passes through the flow meter 20, the fourth single-flow valve 21 and the third valve 8 in sequence, and then enters the annular cavity 30.

[0054] A first valve 6, a second valve 7, and a fourth valve 9 are sequentially installed at the top of the oil pipe 2. The fourth valve 9 is connected to the gas-liquid separator 12. The produced fluid in the oil pipe 2 passes through the first valve 6, the second valve 7, and the fourth valve 9 in sequence before entering the gas-liquid separator 12 for gas-liquid separation.

[0055] In a preferred embodiment, multiple third valves 8 are provided, evenly arranged along the circumference of the well casing 1 and communicating with the annular cavity 30. Simultaneously, multiple fourth valves 9 are provided, each communicating with the second valve 7. Furthermore, the number of third valves 8 corresponds one-to-one with the number of fourth valves 9. Between the corresponding fourth valves 9 and third valves 8, a gas-liquid separator 12, a first compressor 151, a gas storage tank 16, a second compressor 152, and related auxiliary parts are sequentially arranged according to the structure described in the above embodiment, thereby further enhancing the effect of the gas injection lifting process.

[0056] In another embodiment provided by the present invention, existing parts and equipment required for the bubble extrusion process can be provided between the corresponding fourth valve 9 and third valve 8. The parts, equipment, and connection methods required for the bubble extrusion process are prior art and will not be described further here.

[0057] In one embodiment of the present invention, a self-circulating lift method is provided, which uses the self-circulating lift device 100 provided according to the present invention to pressurize the gas produced in the well and reinject it to lift the gas and water mixture in the tubing, thereby realizing continuous gas injection and production.

[0058] In conjunction with the self-circulating lifting device 100 provided according to the present invention, the detailed steps of the self-circulating lifting method provided according to the present invention are as follows.

[0059] The first sensor 11 and the second sensor 22 transmit the pressure data from the first pressure gauge 10 and the second pressure gauge 23 to the control mechanism 17 in real time. The control mechanism 17 calculates the amount of liquid accumulated in the wellbore based on this pressure data. When the amount of liquid accumulated in the wellbore is low and less than a set threshold, it indicates that the formation energy of the gas well is relatively sufficient. At this time, the liquid can be drained normally using the existing foaming drainage process. The foaming drainage agent is injected from the annular cavity 30 and enters the tubing 2 through the circulation hole 51 of the multi-functional working cylinder 5, thus implementing the foaming drainage process normally.

[0060] The first sensor 11 and the second sensor 22 transmit the pressure data of the first pressure gauge 10 and the second pressure gauge 23 to the control mechanism 17 in real time. The control mechanism 17 calculates the amount of liquid accumulated in the wellbore based on these pressure data. When the amount of liquid accumulated in the wellbore is large and exceeds the set threshold, the control mechanism 17 feeds back the control signal to the first compressor 151 and the second compressor 152, and the first compressor 151 and the second compressor 152 start.

[0061] After the first compressor 151 and the second compressor 152 are started, the natural gas in the gas storage tank 16 enters the suction port of the second compressor 152 through the third one-way valve 18. After being pressurized in the second compressor 152, the natural gas flows out from the outlet of the second compressor 152, passes through the flow meter 20, the fourth one-way valve 21, and the third valve 8 into the annular cavity 30, and then enters the oil pipe 2 through the circulation hole 51 of the multi-functional working cylinder 5, lifting the accumulated liquid in the oil pipe 2 to the wellhead (the upper end of the oil pipe 2), and then enters the gas-liquid separator 12 in sequence through the first valve 6, the second valve 7 and the fourth valve 9.

[0062] Inside the gas-liquid separator 12, the mixture of natural gas and water is separated into natural gas and liquid. The separated liquid enters the wastewater tank 13, while a portion of the separated natural gas is supplied to users, and the remaining portion passes through the first one-way valve 14 into the first compressor 151. After being pressurized in the first compressor 151, the natural gas passes through the second one-way valve 19 into the gas storage tank 16, thus completing one cycle. This cyclical operation enables the use of natural gas produced within the well itself for gas injection and lifting processes, eliminating the need for an external gas source. This broadens the application range of the process, allowing construction in exploration wells and remote wells where high-pressure gas sources are unavailable due to inadequate or incomplete pipeline networks.

[0063] After a period of gas injection and lifting, when the control mechanism 17 determines that the amount of liquid in the wellbore is less than the set threshold, the control mechanism 17 sends a control signal to the first compressor 151 and the second compressor 152 to stop the first compressor 151 and the second compressor 152. The gas well produces gas by its own energy or by using the bubble drainage process until the amount of liquid increases to the set threshold again. Then, the control mechanism 17 controls the first compressor 151 and the second compressor 152 to start again.

[0064] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0065] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0066] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0067] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A self-circulating lifting device, a tubing (2) is arranged in a wellbore casing (1), an annular cavity (30) is formed between the tubing (2) and the wellbore casing (1), characterized in that, The self-circulation lifting device comprises, in sequence from the upper end of the oil pipe (2) to the upper end of the annular cavity (30), a gas-liquid separator (12), a first compressor (151) and a gas storage tank (16), The gas in the gas storage tank (16) is injected into the annular cavity (30), and then enters the oil pipe (2) to lift the mixed fluid of gas and water in the oil pipe (2), the mixed fluid flows out from the upper end of the oil pipe (2), the gas is separated out through the gas-liquid separator (12), and the separated gas is stored in the gas storage tank (16) through the first compressor (151), and the cycle is repeated.

2. The self-circulating lift device of claim 1, wherein, A packer (4) is arranged in the annular cavity (30), the packer (4) is located above the downhole perforated section (3), a multifunctional working barrel (5) is arranged on the oil pipe (2), the multifunctional working barrel (5) is located above the packer (4), and the gas in the annular cavity (30) can enter the oil pipe (2) through the multifunctional working barrel (5).

3. The self-circulating lift device of claim 1, wherein, A first check valve (14) is arranged between the gas-liquid separator (12) and the first compressor (151), and a second check valve (19) is arranged between the first compressor (151) and the gas storage tank (16).

4. Self-circulating lifting device according to any one of claims 1-3, characterized in that A second compressor (152) is arranged between the gas storage tank (16) and the annular cavity (30).

5. The self-circulating lift device of claim 4, wherein, A third check valve (18) is arranged between the gas storage tank (16) and the second compressor (152), and a fourth check valve (21) is arranged between the second compressor (152) and the annular cavity (30).

6. The self-circulating lift device according to any one of claims 1 to 3, characterized in that A first pressure gauge (10) is arranged at the upper end of the oil pipe (2), and a second pressure gauge (23) is arranged at the upper end of the annular cavity (30).

7. The self-circulating lift device of claim 6, wherein, The self-circulation lifting device further comprises a control mechanism (17), the control mechanism (17) is electrically connected with the first pressure gauge (10) through a first sensor (11), the control mechanism (17) is electrically connected with the second pressure gauge (23) through a second sensor (22), and the control mechanism (17) is electrically connected with the first compressor (151).

8. The self-circulating lift device according to any one of claims 1 to 3, characterized in that A flow meter (20) is arranged between the gas storage tank (16) and the annular cavity (30).

9. The self-circulating lift device according to any one of claims 1 to 3, characterized in that, The self-circulation lifting device further comprises a sewage pool (13), the sewage pool (13) is connected with the gas-liquid separator (12), and the sewage pool (13) is used for receiving the water separated out by the gas-liquid separator (12).

10. A self-circulating lift method, characterized by, The self-circulation lifting device according to any one of claims 1-9 is used to pressurize the gas extracted from a well and then reinject, lift the mixed fluid of gas and water in the oil pipe, and realize continuous gas injection mining.

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