Oilfield oxygen reduction air foam hybrid flooding injection and extraction method and system

Abstract

The invention relates to the technical field of oil displacement, in particular to an oil field oxygen reduction air and foam hybrid displacement injection and extraction method and system. Oxygen reduction air and foam are sucked into a negative pressure ejector through the negative pressure ejector; the mixing ratio of the final oxygen-reduced air to the foam is adjusted through a bypass pipeline and a control pipeline; if the gas flow is insufficient, the gas flow of the bypass pipeline is increased; if the foam flow is insufficient, the flow of the bypass pipeline is reduced, the gas flow of the control pipeline is increased to increase the pressure of the ground foam input pipeline, and then the foam flow is increased; and finally, a mixed medium composed of the oxygen-reduced air reaching the preset injection value and the foam is injected into an external injection well for oil displacement, and meanwhile, different technologies are adopted for gathering and transportation according to different gas-liquid ratios of gas-liquid mixtures produced by oil wells of the external injection well.

Description

Technical Field

[0001] The present invention relates to the technical field of oil recovery, and in particular to an oilfield oxygen-reduced air foam mixed drive injection and production method and system. Background Art

[0002] The oxygen-reduced air foam oil recovery technology organically combines oxygen-reduced air recovery and foam recovery. It injects oxygen-reduced air and foam into the formation, which greatly increases the injection formation pressure to achieve oil recovery while reducing the amount of foam used. The combination of the two can not only effectively reduce costs, but also achieve better results, thereby increasing the oil production of a single well. It is one of the most promising ways to tap potential and increase efficiency.

[0003] The existing technology mainly realizes oxygen-reduced air foam oil recovery by alternately injecting foam and oxygen-reduced air. The fusion of foam and oxygen-reduced air is mainly carried out underground. Its disadvantages are that the fusion of oxygen-reduced air and foam is uneven, and the foaming effect is difficult to control underground. The oil recovery effect is not as good as fully merging the foam and oxygen-reduced air on the ground and then injecting them into the formation.

[0004] Prior art 1, in the patent "A two-stage oxygen-reduced air foam oil recovery ground injection device" with announcement number CN215927345U, the solution proposed is to alternately inject oxygen-reduced air and foam, stop injecting foam when injecting oxygen-reduced air, and stop injecting oxygen-reduced air when injecting foam.

[0005] Prior art 2, in the patent "Gas-Liquid Mixed Foam Flooding System" with announcement number CN215718660U, nitrogen is generated and pressurized through the gas injection subsystem, water is added and pressurized through the liquid injection subsystem, and then reaches the mixing and injection skid for mixing. The liquid pressure of the nitrogen is difficult to balance and thus difficult to achieve smooth mixing and flow downstream; Prior art 3, in the patent "Ground foam injection device based on Venturi effect" with announcement number CN211692423U, negative pressure is generated at the neck of the Venturi tube to mix the foam and gas to achieve injection, but this simple application of the Venturi tube to mix foam and gas method is difficult to control the mixing ratio of foam and gas. When the foam flows through the neck of the Venturi tube, negative pressure is generated to suck in the gas to achieve mixing of foam and gas. If the gas suction amount is to be increased, it can only be done by increasing the foam flow rate, and the control means are single; therefore, it is impossible to achieve mixing of foam and gas in a certain proportion. Summary of the invention

[0006] In view of the above problems, the present invention proposes an oilfield oxygen-reduced air foam mixed drive injection and production method and system which utilizes the Venturi principle to achieve mixing of foam and gas while being able to accurately control the mixing ratio to meet the needs of oilfield air foam drive.

[0007] The technical solution of the present invention is: The present invention provides an oilfield oxygen-reduced air foam mixed drive injection and production method; An oilfield oxygen-reduced air foam mixed drive injection and production method, a surface gas input pipeline and a surface foam input pipeline are both output to an external injection well through a negative pressure ejector; the negative pressure ejector is also connected in parallel with a bypass pipeline; the surface gas input pipeline is also connected to the surface foam input pipeline through a control pipeline; If the gas flow is insufficient, increase the gas flow in the bypass line; If the foam flow is insufficient, reduce the flow of the bypass line and increase the gas flow of the control line to increase the pressure of the ground foam input line and thus increase the foam flow; The output gas of the ground gas input pipeline is oxygen-reduced air, and the oxygen concentration of the oxygen-reduced air is less than 5%.

[0008] The produced fluid of the external injection well includes oil and gas separate transmission and oil and gas mixed transmission. If the gas-oil ratio is greater than 50m3 / t, oil and gas separate transmission is adopted; otherwise, oil and gas mixed transmission is adopted.

[0009] The present invention proposes an oilfield oxygen-reduced air foam mixed drive injection and production system; A system for realizing the oilfield oxygen-reduced air foam mixed drive injection and production method, comprising a ground gas input pipeline and a ground foam input pipeline; the ground gas input pipeline and the ground foam input pipeline are respectively connected to a negative pressure ejector; a flow meter is provided on the inlet pipeline of the negative pressure ejector; the negative pressure ejector is also provided with a bypass pipeline and an outlet pipeline; and also comprises a control pipeline, the inlet end of the control pipeline is connected to the ground gas input pipeline, and the outlet end is connected to the ground foam input pipeline; the bypass pipeline is provided with a bypass gas flow regulating valve and a bypass gas flow meter, the ground foam input pipeline is provided with a foam flow regulating valve and a foam flow meter, and the control pipeline is provided with a gas control flow meter and a flow regulating valve.

[0010] The ground foam input pipeline includes a foam liquid preparation tank and a foam storage tank connected in sequence; the inlet end of the foam liquid preparation tank is also connected to a water supply branch and a foaming agent branch; a foam stabilizer branch is also provided on the connecting pipeline between the foam liquid preparation tank and the foam storage tank; wherein, the foam liquid preparation tank and the foam storage tank are both pressurized, and the pressure of the foam preparation tank is higher than the pressure of the foam storage tank; a foam one-way valve is also provided on the connecting pipeline between the foam storage tank and the negative pressure ejector.

[0011] The clean water branch includes a clean water tank and a lifting pump connected in sequence, the foaming agent branch includes a foaming agent storage tank and a foaming agent dosing pump connected in sequence; the lifting pump and the dosing pump are both connected to the foam liquid preparation tank; the foam stabilizer branch includes a foam stabilizer storage tank and a foam stabilizer dosing pump connected in sequence.

[0012] The ground gas input pipeline includes a membrane nitrogen skid, an oxygen analyzer, a gas flow meter, an oxygen concentration control valve and a compressor connected in sequence; the inlet end of the control pipeline is connected to the outlet pipeline of the compressor, and the outlet end is connected to the foam preparation tank; a gas control one-way valve and a gas control pressure gauge are also provided therebetween.

[0013] The outlet pipeline is connected to an external injection well; the outlet pipeline comprises an outlet one-way valve and an injection pump connected in sequence; the outlet of the external injection well is connected to a production pipeline.

[0014] The production pipeline includes an oil outlet pipeline and a gas outlet pipeline; it also includes an oil and gas mixed pipeline connected to the oil outlet pipeline and the gas outlet pipeline; it also includes a regulating pipeline, the input end of the regulating pipeline is connected to the gas outlet pipeline, and the output end is connected to the oil outlet pipeline, and the regulating pipeline is provided with a casing gas regulating valve.

[0015] The oil outlet pipeline is provided with an oil outlet one-way valve, an oil outlet oxygen analyzer and an oil outlet pressure sensor; the air outlet pipeline is provided with a casing gas one-way valve, a casing gas oxygen analyzer and a casing gas pressure sensor; the oil-gas mixed transmission pipeline comprises a first oil-gas mixer, a twin-screw oil-gas mixed transmission pump and a second oil-gas mixer which are connected in sequence; the inlet end of the first oil-gas mixer is respectively connected to the oil outlet pipeline and the air outlet pipeline.

[0016] The technical effects of the present invention are: The present invention sucks oxygen-reduced air and foam into a negative pressure ejector through a negative pressure ejector; adjusts the final mixing ratio of oxygen-reduced air and foam through a bypass pipeline and a control pipeline; if the gas flow is insufficient, increases the gas flow of the bypass pipeline; if the foam flow is insufficient, reduces the flow of the bypass pipeline, increases the gas flow of the control pipeline to increase the pressure of the ground foam input pipeline, and then increases the foam flow; finally, injects the mixed medium consisting of oxygen-reduced air and foam that reaches a preset injection value into an external injection well for oil recovery, and adopts different processes for collection and transportation according to the different gas-liquid ratios of the gas-liquid mixture produced by the oil well of the external injection well. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the present invention.

[0018] Figure 2 It is a schematic diagram of the oil and gas distribution process of the present invention.

[0019] Figure 3 It is a schematic diagram of the oil and gas mixed transportation process of the present invention.

[0020] Reference numerals: 1. membrane nitrogen skid; 2. oxygen analyzer; 3. gas flow meter; 4. oxygen concentration control valve; 5. compressor; 6. negative pressure ejector; 7. bypass gas flow regulating valve; 8. gas control flow meter; 9. gas control pressure gauge; 10. clean water tank; 11. lifting pump; 12. foam preparation tank; 13. foaming agent storage tank; 14. foam stabilizer storage tank; 15. foam storage tank; 16. foam one-way valve; 17. foam flow regulating valve; 18. injection pump; 19. Gas control one-way valve; 20. Flow regulating valve; 21. Bypass gas flowmeter; 22. Outlet one-way valve; 23. Foam flowmeter; 24. Flowmeter; 25. Oil outlet pressure sensor; 26. First oil-gas mixer; 27. Twin-screw oil-gas mixed delivery pump; 28. Second oil-gas mixer; 29. ​​Foaming agent dosing pump; 30. Foam stabilizer dosing pump; 31. Oil outlet one-way valve; 32. Oil outlet oxygen analyzer; 33. Casing gas one-way valve; 34. Casing gas oxygen analyzer; 35. Casing gas pressure sensor; 36. Casing gas regulating valve. DETAILED DESCRIPTION

[0021] Example 1 - An oilfield oxygen-reduced air foam mixed drive injection and production method; An oilfield oxygen-reduced air foam mixed drive injection and production method, a surface gas input pipeline and a surface foam input pipeline are both output to an external injection well through a negative pressure ejector 6; the negative pressure ejector 6 is also connected in parallel with a bypass pipeline; the surface gas input pipeline is also connected to the surface foam input pipeline through a control pipeline; If the gas flow is insufficient, increase the gas flow in the bypass line; If the foam flow is insufficient, reduce the flow of the bypass line and increase the gas flow of the control line to increase the pressure of the ground foam input line and thus increase the foam flow; The gas source of the ground gas input pipeline is oxygen-reduced air, and the oxygen concentration of the oxygen-reduced air is less than 5%; The produced fluid of the external injection well includes oil and gas separate transmission and oil and gas mixed transmission; if the gas-oil ratio is greater than 50m 3 / t, oil and gas are transported separately; otherwise, oil and gas are transported together.

[0022] Example 2 - An oilfield oxygen-reduced air foam mixed drive injection and production system; A system for realizing the oilfield oxygen-reduced air foam mixed drive injection and production method, comprising a surface gas input pipeline and a surface foam input pipeline; the surface gas input pipeline and the surface foam input pipeline are respectively connected to a negative pressure ejector 6; a flow meter 24 is provided on the inlet pipeline of the negative pressure ejector 6; the negative pressure ejector 6 is also provided with a bypass pipeline and an outlet pipeline; and also comprises a control pipeline, the inlet end of the control pipeline is connected to the surface gas input pipeline, and the outlet end is connected to the surface foam input pipeline; the bypass pipeline is provided with a bypass gas flow regulating valve 7 and a bypass gas flow meter 21, the surface foam input pipeline is provided with a foam flow regulating valve 17 and a foam flow meter 23, and the control pipeline is provided with a gas control flow meter 8 and a flow regulating valve 20; wherein the bypass pipeline is adjusted according to a preset injection value, and the control pipeline is used to supplement a certain pressure to the surface foam input pipeline; The specific implementation process of this embodiment is as follows: the oxygen-reduced air input by the ground gas input pipeline enters the negative pressure ejector 6; the foam input by the ground foam input pipeline also enters the negative pressure ejector 6; the flow conditions of the foam flow meter 23 and the flow meter 24 are compared with the preset injection value. If the gas flow counted by the flow meter 24 is less than the preset injection value, the opening of the bypass gas flow regulating valve 7 is increased to increase the gas flow of the bypass pipeline, and continue mixing in the downstream flow process; if the foam flow counted by the foam flow meter 23 is less than the preset injection value, the opening of the bypass gas flow regulating valve 7 is reduced, and the opening of the flow regulating valve 20 is increased to increase the suction and thrust on the foam, and at the same time, the opening of the foam flow regulating valve 17 is increased to increase the foam entering the negative pressure ejector 6.

[0023] Example 3 On the basis of Example 2, the invention further includes: The ground foam input pipeline includes a foam liquid preparation tank and a foam storage tank 15 connected in sequence; the inlet end of the foam liquid preparation tank is also connected to a water supply branch and a foaming agent branch; a foam stabilizer branch is also provided on the connecting pipeline between the foam liquid preparation tank and the foam storage tank 15; wherein, the foam liquid preparation tank and the foam storage tank 15 are both pressurized, and the pressure of the foam preparation tank 12 is higher than the pressure of the foam storage tank 15; a foam one-way valve 16 is also provided on the connecting pipeline between the foam storage tank 15 and the negative pressure ejector 6; The clean water branch includes a clean water tank 10 and a lifting pump 11 connected in sequence, and the foaming agent branch includes a foaming agent storage tank 13 and a foaming agent dosing pump 29 connected in sequence; the lifting pump 11 and the dosing pump are both connected to the foam liquid preparation tank; the clean water tank 10 transports clean water to the foam preparation tank 12 through the lifting pump 11, and the lifting pump 11 adopts a variable frequency plunger pump. When the pressure of the foam preparation tank 12 increases, the clean water can still be lifted to the foam preparation tank 12; The foaming agent is added to the foam preparation tank 12 through the foaming agent dosing pump 29; the outlet pipeline of the foam preparation tank 12 is located at the upper part near the top, and the foam in the foam preparation tank 12 is transported downstream under pressure; the foam stabilizer branch includes a foam stabilizer storage tank 14 and a foam stabilizer dosing pump 30 connected in sequence. The foam stabilizer is quantitatively added to the connecting pipeline between the foam liquid preparation tank and the foam storage tank 15 through the foam stabilizer dosing pump 30; the foam in the foam storage tank 15 continues to be transported downstream under pressure.

[0024] The ground gas input pipeline comprises a membrane nitrogen skid 1, an oxygen analyzer 2, a gas flowmeter 3, an oxygen concentration control valve 4 and a compressor 5 which are connected in sequence; the gas source of the ground gas input pipeline is air, and the output gas is oxygen-reduced air; the air passes through the membrane nitrogen skid 1 to remove oxygen, the oxygen analyzer 2 measures the oxygen concentration at the outlet of the membrane nitrogen skid 1, and the oxygen concentration at the outlet of the membrane nitrogen skid 1 is adjusted by the oxygen concentration control valve 4. Under normal working conditions, when the oxygen concentration control valve 4 is opened widely, the oxygen concentration at the outlet of the membrane nitrogen skid 1 is high, and when the oxygen concentration control valve 4 is opened slightly, the oxygen concentration at the outlet of the membrane nitrogen skid 1 is low.

[0025] Finally, the foam and oxygen-reduced air are sucked into the negative pressure ejector 6 by the negative pressure of the negative pressure ejector 6, so that the oxygen-reduced air and foam are mixed. After the oxygen-reduced air and foam are mixed, they are output through the outlet pipeline.

[0026] The inlet end of the control pipeline is connected to the outlet pipeline of the compressor 5, and the outlet end is connected to the foam preparation tank 12; a gas control check valve 19 and a gas control pressure gauge 9 are also provided therebetween. The control pipeline realizes the supplement of a certain pressure to the ground foam input pipeline.

[0027] Example 4 On the basis of Example 3, the invention further includes: The outlet pipeline is connected to an external injection well; the outlet pipeline includes an outlet check valve 22 and an injection pump 18 connected in sequence; the outlet of the external injection well is connected to a production pipeline; the production pipeline includes an oil outlet pipeline and a gas outlet pipeline; and also includes an oil-gas mixed transportation pipeline connected to both the oil outlet pipeline and the gas outlet pipeline; and also includes a regulating pipeline, the input end of the regulating pipeline is connected to the gas outlet pipeline, and the output end is connected to the oil outlet pipeline, and the regulating pipeline is provided with a casing gas regulating valve 36; The oil outlet pipeline is provided with an oil outlet check valve 31, an oil outlet oxygen analyzer 32 and an oil outlet pressure sensor 25; the gas outlet pipeline is provided with a casing gas check valve 33, a casing gas oxygen analyzer 34 and a casing gas pressure sensor 35; the oil-gas mixed transmission pipeline comprises a first oil-gas mixer 26, a twin-screw oil-gas mixed transmission pump 27 and a second oil-gas mixer 28 connected in sequence; the inlet end of the first oil-gas mixer 26 is connected to the oil outlet pipeline and the gas outlet pipeline respectively; The production of external injection wells includes two working conditions: if the gas-oil ratio is greater than 50m 3 / t, oil and gas are transported separately, such as Figure 2 , that is, the produced liquid enters the oil outlet pipeline for external transmission, and the casing gas is tested for oxygen content by the casing gas oxygen analyzer 34 and then transmitted through the gas outlet pipeline; otherwise, oil and gas mixed transmission is adopted, such as Figure 3 When oil and gas are mixed, the casing gas enters the oil outlet pipeline through the casing gas regulating valve 36. The casing gas regulating valve 36 is used to make the pressure of the gas outlet pipeline higher than the pressure of the oil outlet pipeline by 0.1MPa, so as to ensure that the casing gas enters the oil outlet pipeline; after the casing gas enters the oil outlet pipeline, it first passes through the first oil-gas mixer 26, which fully mixes the gas, water, oil, wax, etc. to prevent gas blockage and wax deposition in the downstream pipeline; then it is transported out through the twin-screw oil-gas mixed transmission pump 27 and the second oil-gas mixer 28 in turn, and the gas, water, oil, wax, etc. are fully mixed again to prevent gas blockage and wax deposition in the downstream pipeline. The gas-liquid homogenization before and after the pump is achieved, and two-stage mixing is achieved to improve the oil-gas mixed transmission effect, reduce pump pressure, reduce energy consumption, and avoid oil-gas mixed transmission gas blockage and transmission stop accidents.

Claims

1. An oilfield oxygen-reduced air foam mixed flooding injection and production method, characterized in that: Here’s how: The surface gas input pipeline and the surface foam input pipeline are both output to an external injection well through a negative pressure ejector (6); the negative pressure ejector (6) is also connected in parallel with a bypass pipeline; the surface gas input pipeline is also connected to the surface foam input pipeline through a control pipeline; If the gas flow is insufficient, increase the gas flow in the bypass line; If the foam flow is insufficient, reduce the flow of the bypass line and increase the gas flow of the control line to increase the pressure of the ground foam input line and thus increase the foam flow.

2. The oilfield oxygen-reduced air foam mixed flooding injection and production method according to claim 1, characterized in that: The output gas of the ground gas input pipeline is oxygen-reduced air, and the oxygen concentration of the oxygen-reduced air is less than 5%.

3. The oilfield oxygen-reduced air foam mixed flooding injection and production method according to claim 1, characterized in that: The produced fluid of the external injection well includes oil and gas separate transmission and oil and gas mixed transmission; if the gas-oil ratio is greater than 50m 3 / t, oil and gas are transported separately; otherwise, oil and gas are transported together.

4. A system for implementing the oilfield oxygen-reduced air foam mixed flooding injection and production method as described in claim 1, comprising a surface gas input pipeline and a surface foam input pipeline; characterized in that: The ground gas input pipeline and the ground foam input pipeline are respectively connected to a negative pressure ejector (6); a flow meter (24) is provided on the inlet pipeline of the negative pressure ejector (6); the negative pressure ejector (6) is also provided with a bypass pipeline and an outlet pipeline; and also includes a control pipeline, the inlet end of the control pipeline is connected to the ground gas input pipeline, and the outlet end is connected to the ground foam input pipeline; the bypass pipeline is provided with a bypass gas flow regulating valve (7) and a bypass gas flow meter (21), the ground foam input pipeline is provided with a foam flow regulating valve (17) and a foam flow meter (23), and the control pipeline is provided with a gas control flow meter (8) and a flow regulating valve (20).

5. The oilfield oxygen-reduced air foam mixed flooding injection and production system according to claim 4, characterized in that: The ground foam input pipeline comprises a foam liquid preparation tank and a foam storage tank (15) connected in sequence; the inlet end of the foam liquid preparation tank is also connected to a water supply branch and a foaming agent branch; a foam stabilizer branch is also provided on the connecting pipeline between the foam liquid preparation tank and the foam storage tank (15); wherein the foam liquid preparation tank and the foam storage tank (15) are both pressurized, and the pressure of the foam preparation tank (12) is higher than the pressure of the foam storage tank (15); and a foam one-way valve (16) is also provided on the connecting pipeline between the foam storage tank (15) and the negative pressure ejector (6).

6. The oilfield oxygen-reduced air foam mixed flooding injection and production system according to claim 5, characterized in that: The clean water branch comprises a clean water tank (10) and a lifting pump (11) connected in sequence, and the foaming agent branch comprises a foaming agent storage tank (13) and a foaming agent dosing pump (29) connected in sequence; the lifting pump (11) and the dosing pump are both connected to a foam liquid preparation tank; and the foam stabilizer branch comprises a foam stabilizer storage tank (14) and a foam stabilizer dosing pump (30) connected in sequence.

7. The oilfield oxygen-reduced air foam mixed flooding injection and production system according to claim 4, characterized in that: The ground gas input pipeline comprises a membrane nitrogen skid (1), an oxygen analyzer (2), a gas flow meter (3), an oxygen concentration control valve (4) and a compressor (5) which are connected in sequence; the inlet end of the control pipeline is connected to the outlet pipeline of the compressor (5), and the outlet end is connected to the foam preparation tank (12); a gas control one-way valve (19) and a gas control pressure gauge (9) are also provided therebetween.

8. The oilfield oxygen-reduced air foam mixed flooding injection and production system according to claim 4, characterized in that: The outlet pipeline is connected to an external injection well; the outlet pipeline comprises an outlet check valve (22) and an injection pump (18) which are connected in sequence; the outlet of the external injection well is connected to a production pipeline.

9. The oilfield oxygen-reduced air foam mixed flooding injection and production system according to claim 8, characterized in that: The production pipeline includes an oil outlet pipeline and a gas outlet pipeline; also includes an oil and gas mixed pipeline connected to both the oil outlet pipeline and the gas outlet pipeline; and also includes a regulating pipeline, the input end of the regulating pipeline is connected to the gas outlet pipeline, and the output end is connected to the oil outlet pipeline, and the regulating pipeline is provided with a casing gas regulating valve (36).

10. The oilfield oxygen-reduced air foam mixed flooding injection and production system according to claim 9, characterized in that: The oil outlet pipeline is provided with an oil outlet check valve (31), an oil outlet oxygen analyzer (32) and an oil outlet pressure sensor (25); the gas outlet pipeline is provided with a casing gas check valve (33), a casing gas oxygen analyzer (34) and a casing gas pressure sensor (35); the oil-gas mixed transmission pipeline comprises a first oil-gas mixer (26), a twin-screw oil-gas mixed transmission pump (27) and a second oil-gas mixer (28) which are connected in sequence; the inlet end of the first oil-gas mixer (26) is connected to the oil outlet pipeline and the gas outlet pipeline respectively.

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