Reinjection system for associated gas with high CO2 content

Abstract

The utility model relates to a high-CO2-content associated gas reinjection system, aiming at solving the problems that the pressure ratio of each stage of compressor in the existing CO2 associated gas reinjection system is large and the concentration of the initial CO2 associated gas is low. According to the system, the CO2 associated gas reinjection pressure is increased through pressurization of a four-stage compressor, and reinjection of CO2 associated gas in a supercritical state is achieved; coolers and gas-liquid separators are arranged among the compressors of all stages, so that gas cooling and dehydration can be carried out; the molecular sieve dehydrating tower between the second-stage compressor and the third-stage compressor is used for dehydrating water in the associated gas with high CO2 content, so that the corrosion of CO2 and water to the system in the reinjection process is slowed down; and when the yield of the CO2 associated gas is not enough, pure CO2 gas is injected into the gas mixer, and the pure CO2 gas is supplemented and reinjected after being mixed with the CO2 associated gas in the gas mixer. According to the utility model, the purification, compression and dehydration of the associated gas with high CO2 content are combined, so that the reinjection of the associated gas with high CO2 content is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of energy chemical engineering, and particularly relates to a high CO-containing 2 associated gas reinjection system. Background Technique

[0002] Under the background of energy shortage and energy conservation and emission reduction, carbon dioxide flooding, as a tertiary oil recovery technology, has a very broad application prospect in oil fields because it can not only improve the oil recovery rate but also reduce the greenhouse gas CO 2 emissions. However, in the middle and late stages of CO 2 flooding, oil wells will produce a large amount of associated gas rich in CO 2 . Previously, due to the inability to collect and utilize it, most of the CO 2 associated gas was treated by flaring. However, with the development of the construction of carbon capture, utilization and storage (CCUS) projects, directly reinjecting the associated gas rich in CO 2 or mixing it with carbon dioxide gas for reinjection flooding takes into account the requirements of carbon emissions and carbon utilization, reduces environmental pollution, and also improves the oil recovery rate of oil fields. Most of the existing CO 2 associated gas reinjection devices are of secondary or tertiary pressurization. To reach the reinjection pressure of the formation, such a pressurization method increases the compression ratio of each stage of the compressor (the compression ratio is the ratio of the total outlet pressure to the total inlet pressure of the compressor), and thus the power consumption of the compressor increases, resulting in easy damage to the compressor. In addition, the concentration of CO 2 in the initial CO 2 associated gas is low. To reduce the supplementary use of pure CO 2 gas, there is an urgent need for a membrane module device to increase the CO 2 concentration in the associated gas. 2 Content of the Utility Model

[0003] The utility model aims to solve the problems of large compression ratio of each stage of the compressor in the existing CO 2 associated gas reinjection system and low concentration of the initial CO 2 associated gas, and provides a high CO-containing 2 associated gas reinjection system.

[0004] The technical solution adopted by the utility model to solve the above problems is as follows:

[0005] A high CO-containing 2 associated gas reinjection system, which comprises CO 2Associated gas inlet pipe, pre-compressor, pre-cooler, cyclone separator, filter separator, dehydration device, membrane module, first inlet pipe, gas mixer, first-stage compressor, first-stage cooler, first-stage gas-liquid separator, second-stage compressor, second-stage cooler, second-stage gas-liquid separator, second inlet pipe, first molecular sieve dehydration tower, third-stage compressor, fourth inlet pipe, third-stage cooler, third-stage gas-liquid separator, fourth-stage compressor, fourth-stage cooler, exhaust pipe, liquid conveying pipe, liquid buffer tank, drain pipe and pure CO 2 Inlet pipe;

[0006] CO 2 The output end of the associated gas inlet pipe is connected to the pre-compressor, the pre-compressor is connected to the pre-cooler through a pipeline, the pre-cooler is connected to the cyclone separator through a pipeline, the cyclone separator is connected to the filter separator through a pipeline, the filter separator is connected to the dehydration device through a pipeline, the dehydration device is connected to the membrane module through a pipeline, the membrane module is connected to the gas mixer through the first inlet pipe, the gas mixer is connected to the first-stage compressor through a pipeline, the first-stage compressor is connected to the first-stage cooler through a pipeline, the first-stage cooler is connected to the first-stage gas-liquid separator through a pipeline, the first-stage gas-liquid separator is connected to the second-stage compressor through a pipeline, the second-stage compressor is connected to the second-stage cooler through a pipeline, the second-stage cooler is connected to the second-stage gas-liquid separator through a pipeline, the second-stage gas-liquid separator is connected to the first molecular sieve dehydration tower through the second inlet pipe, the first molecular sieve dehydration tower is connected to the third-stage compressor through the fourth inlet pipe, the third-stage compressor is connected to the third-stage cooler through a pipeline, the third-stage cooler is connected to the third-stage gas-liquid separator through a pipeline, the third-stage gas-liquid separator is connected to the fourth-stage compressor through a pipeline, the fourth-stage compressor is connected to the fourth-stage cooler through a pipeline, the input end of the exhaust pipe is connected to the fourth-stage cooler, one end of the liquid conveying pipe is connected to the liquid buffer tank, and the other end of the liquid conveying pipe is respectively connected to the cyclone separator, the filter separator, the first-stage gas-liquid separator, the second-stage gas-liquid separator and the first molecular sieve dehydration tower, the input end of the drain pipe is connected to the liquid buffer tank, pure CO 2 The output end of the inlet pipe is connected to the gas mixer.

[0007] Furthermore, a first inlet valve is installed on the first inlet pipe.

[0008] Furthermore, a second inlet valve is installed on the second inlet pipe.

[0009] Furthermore, an exhaust valve is installed on the exhaust pipe.

[0010] Furthermore, a drain valve is installed on the drain pipe.

[0011] Furthermore, a pure CO inlet valve is installed on the pure CO2 inlet pipe. 2 Inlet valve.

[0012] Further, the system further includes a third intake pipe and a second molecular sieve dehydration tower. The input end of the third intake pipe is connected to the second intake pipe, the output end of the third intake pipe is connected to the air inlet of the second molecular sieve dehydration tower, the air outlet of the second molecular sieve dehydration tower is connected to the fourth intake pipe through a pipeline, and a third intake valve is installed on the third intake pipe.

[0013] The utility model has the following beneficial effects compared with the prior art:

[0014] First, the utility model is a four-stage supercharger. The CO 2 associated gas is compressed by a first-stage compressor, a second-stage compressor, a third-stage compressor and a fourth-stage compressor, which not only increases the injection pressure of the CO 2 associated gas, but also reduces the compression ratio of each stage of the compressor, thereby reducing the power consumption of the compressor and avoiding the damage of the compressor.

[0015] Second, the membrane module of the utility model adopts a hollow fiber membrane module, and the membrane material is a high molecular polymer material polyimide. After the CO 2 associated gas is separated by the membrane, the concentration of CO 2 in the associated gas can be increased, thereby improving the oil displacement efficiency.

[0016] Third, the utility model injects pure CO 2 gas into the gas mixer through a pure CO 2 intake pipe to increase the CO 2 content in the initial CO 2 associated gas, thereby improving the oil displacement efficiency.

[0017] Fourth, the utility model adopts the method of inter-stage dehydration, that is, between the second-stage compressor and the third-stage compressor, the high-content CO 2 associated gas is deeply dehydrated by a molecular sieve dehydration tower, the moisture in the high-content CO 2 associated gas is removed, and the corrosion of the system caused by the reaction of CO with water during the injection process is slowed down.

[0018] Figure 1 is the overall structural schematic diagram of the utility model. Detailed implementation manners

[0019] Detailed implementation manner one: Combine Figure 1Description of this embodiment. This embodiment includes a CO2 associated gas inlet pipe 1, a pre-compressor 2, a pre-cooler 3, a cyclone separator 4, a filter separator 5, a dehydration device 6, a membrane module 7, a first inlet pipe 8, a gas mixer 9, a first-stage compressor 10, a first-stage cooler 11, a first-stage gas-liquid separator 12, a second-stage compressor 13, a second-stage cooler 14, a second-stage gas-liquid separator 15, a second inlet pipe 16, a first molecular sieve dehydration tower 17, a third-stage compressor 18, a fourth inlet pipe 19, a third-stage cooler 20, a third-stage gas-liquid separator 21, a fourth-stage compressor 22, a fourth-stage cooler 23, an exhaust pipe 24, a liquid pipe 25, a liquid buffer tank 26, a drain pipe 27, and a pure CO 2 inlet pipe 28;

[0020] CO 2 The output end of the CO2 associated gas inlet pipe 1 is connected to the pre-compressor 2. The pre-compressor 2 is connected to the pre-cooler 3 through a pipeline. The pre-cooler 3 is connected to the cyclone separator 4 through a pipeline. The cyclone separator 4 is connected to the filter separator 5 through a pipeline. The filter separator 5 is connected to the dehydration device 6 through a pipeline. The dehydration device 6 is connected to the membrane module 7 through a pipeline. The membrane module 7 is connected to the gas mixer 9 through the first inlet pipe 8. The gas mixer 9 is connected to the first-stage compressor 10 through a pipeline. The first-stage compressor 10 is connected to the first-stage cooler 11 through a pipeline. The first-stage cooler 11 is connected to the first-stage gas-liquid separator 12 through a pipeline. The first-stage gas-liquid separator 12 is connected to the second-stage compressor 13 through a pipeline. The second-stage compressor 13 is connected to the second-stage cooler 14 through a pipeline. The second-stage cooler 14 is connected to the second-stage gas-liquid separator 15 through a pipeline. The second-stage gas-liquid separator 15 is connected to the first molecular sieve dehydration tower 17 through the second inlet pipe 16. The first molecular sieve dehydration tower 17 is connected to the third-stage compressor 18 through the fourth inlet pipe 19. The third-stage compressor 18 is connected to the third-stage cooler 20 through a pipeline. The third-stage cooler 20 is connected to the third-stage gas-liquid separator 21 through a pipeline. The third-stage gas-liquid separator 21 is connected to the fourth-stage compressor 22 through a pipeline. The fourth-stage compressor 22 is connected to the fourth-stage cooler 23 through a pipeline. The input end of the exhaust pipe 24 is connected to the fourth-stage cooler 23. One end of the liquid pipe 25 is connected to the liquid buffer tank 26. The other end of the liquid pipe 25 is respectively connected to the cyclone separator 4, the filter separator 5, the first-stage gas-liquid separator 12, the second-stage gas-liquid separator 15, and the first molecular sieve dehydration tower 17. The input end of the drain pipe 27 is connected to the liquid buffer tank 26. The pure CO 2 The output end of the inlet pipe 28 is connected to the gas mixer 9. The first-stage compressor 10, the second-stage compressor 13, the third-stage compressor 18, and the fourth-stage compressor 22 adopt a symmetric balanced reciprocating compressor, with four columns and four-stage compression, which can achieve a higher reinjection pressure. The coolers and gas-liquid separators arranged between each stage of the compressor can carry out CO 2 associated gas cooling and dehydration to prevent CO 2Corrosion of associated gas phase change and hydrate. The entire system is made of stainless steel to reduce the corrosion damage of hydrates.

[0021] A first intake valve 8-1 is installed on the first intake pipe 8. The first intake valve 8-1 is used to control the intake volume of CO 2 in the associated gas entering the gas mixer 9.

[0022] A second intake valve 16-1 is installed on the second intake pipe 16. The first intake valve 16-1 is used to control the intake volume of the first molecular sieve dehydration tower 17.

[0023] An exhaust valve 24-1 is installed on the exhaust pipe 24. The exhaust valve 24-1 is used to control the exhaust volume of the exhaust pipe 24.

[0024] A drain valve 27-1 is installed on the drain pipe 27. The drain valve 27-1 is used to control the drainage volume of the drain pipe 27.

[0025] The pure CO 2 intake pipe 28 is installed with a pure CO 2 intake valve 28-1. The pure CO 2 intake valve 28-1 is used to control the pure CO 2 gas entering the gas mixer 9.

[0026] Specific Embodiment 2: Combined with Figure 1 To illustrate this embodiment, this embodiment further includes a third intake pipe 29 and a second molecular sieve dehydration tower 30. The input end of the third intake pipe 29 is connected to the second intake pipe 16, the output end of the third intake pipe 29 is connected to the intake port of the second molecular sieve dehydration tower 30, the outlet of the second molecular sieve dehydration tower 30 is connected to the fourth intake pipe 19 through a pipeline, and a third intake valve 29-1 is installed on the third intake pipe 29. This setting is to ensure that when the material of one of the molecular sieve dehydration towers needs to be replaced, the other molecular sieve dehydration tower can still carry out the dehydration treatment work normally, guaranteeing the smooth operation of the associated gas dehydration work. The technical features not disclosed in this embodiment are the same as those in Specific Embodiment 1.

[0027] Working principle:

[0028] CO 2 The associated gas enters from the associated gas intake pipe 1 and is pressurized by the primary compressor 2 to the working conditions of membrane separation. The CO 2 in the associated gas. The associated gas passes through the primary cooler 3 to cool down the temperature of the compressed CO 2 associated gas, and then enters the cyclone separator 4 to remove water and droplets. The CO 2 associated gas comes out of the cyclone separator 4 and enters the filter separator 5 to remove smaller droplets and solid impurities. After that, the CO 2 associated gas comes out of the filter separator 5 and enters the gas mixer 9. 2The associated gas enters the dehydration device 6 for further dehydration and then enters the membrane module 7. 2 The associated gas is separated through the membrane module 7 to obtain a higher concentration of CO 2 The associated gas then enters the gas mixer 9. 2 When the associated gas production is insufficient, pure CO 2 The gas inlet pipe 28 injects pure CO into the gas mixer 9. 2 Gas, pure CO 2 The gas is mixed with CO in the gas mixer 9. 2 Associated gas is mixed and then reinjected. 2 The associated gas production is sufficient and the CO in the gas 2 When the concentration is greater than 93%, pure CO can be turned off 2 Inlet valve 28-1, by CO 2 Associated gas reinjection for oil recovery. 2 The associated gas enters the primary compressor 10 for compression and then passes through the primary cooler 11 to reduce CO 2 The associated gas enters the primary gas-liquid separator 12 after the temperature is reached, and the primary gas-liquid separator 12 removes CO 2 Liquid in associated gas (i.e. liquid formed by compression and cooling between stages), CO 2 The associated gas enters the secondary compressor 13 for pressurization, CO 2 After the associated gas comes out of the secondary compressor 13, it is output through the secondary cooler 14 and the secondary gas-liquid separator 15 and then enters the first molecular sieve dehydration tower 17 or the second molecular sieve dehydration tower 30 for deep dehydration to remove the high CO 2 The water in the associated gas is removed to slow down the CO 2 The system is corroded by the action of water, and the dehydrated CO 2 The associated gas enters the third-stage compressor 18 for further compression, after which CO 2 The associated gas enters the third-stage cooler 20, then enters the third-stage gas-liquid separator 21, and then enters the fourth-stage compressor 22 for pressurization. The compressed CO 2 The associated gas is cooled in the four-stage cooler 23 and then injected into the ground through the exhaust pipe 24 for oil recovery. 2 Due to the influence of phase change, hydrate and corrosion, the interstage cooling temperature is controlled at 40°C; the liquid separated by the first-stage gas-liquid separator 12, the second-stage gas-liquid separator 15 and the third-stage gas-liquid separator 21 is discharged to the liquid buffer tank 26 and then discharged from the system through the drain pipe 27.

[0029] In CO 2 Before the associated gas enters the pre-compressor 2 (the produced CO 2 The pressure of associated gas is 0.2MPa. After being treated by this system, CO 2The reinjection pressure of associated gas can reach 28 MPa to achieve the reinjection of CO 2 under supercritical conditions. The reinjection of associated gas at high pressure improves the injection efficiency and reduces the injection cost.

Claims

1. A high-CO2 associated gas reinjection system, characterized by: The system comprises a CO2 associated gas inlet pipe (1), a front compressor (2), a front cooler (3), a cyclone separator (4), a filter separator (5), a dehydration device (6), a membrane assembly (7), a first inlet pipe (8), a gas mixer (9), a first-stage compressor (10), a first-stage cooler (11), a first-stage gas-liquid separator (12), a second-stage compressor (13), a second-stage cooler (14), a second-stage gas-liquid separator (15), a second inlet pipe (16), a first molecular sieve dehydration tower (17), a third-stage compressor (18), a fourth inlet pipe (19), a third-stage cooler (20), a third-stage gas-liquid separator (21), a fourth-stage compressor (22), a fourth-stage cooler (23), an exhaust pipe (24), a liquid pipe (25), a liquid buffer tank (26), a liquid discharge pipe (27) and a pure CO2 inlet pipe (28); The output end of the CO2 associated gas inlet pipe (1) is connected to the pre-compressor (2), the pre-compressor (2) is connected to the pre-cooler (3) through a pipeline, the pre-cooler (3) is connected to the cyclone separator (4) through a pipeline, the cyclone separator (4) is connected to the filter separator (5) through a pipeline, the filter separator (5) is connected to the dehydration device (6) through a pipeline, the dehydration device (6) is connected to the membrane assembly (7) through a pipeline, and the membrane assembly (7) is connected to the gas mixer (9) through a first inlet pipe (8). The gas mixer (9) is connected to the primary compressor (10) through a pipeline, the primary compressor (10) is connected to the primary cooler (11) through a pipeline, the primary cooler (11) is connected to the primary gas-liquid separator (12) through a pipeline, the primary gas-liquid separator (12) is connected to the secondary compressor (13) through a pipeline, the secondary compressor (13) is connected to the secondary cooler (14) through a pipeline, the secondary cooler (14) is connected to the secondary gas-liquid separator (15) through a pipeline, and the secondary gas-liquid separator ( The first molecular sieve dehydration tower (15) is connected to the first molecular sieve dehydration tower (17) through a second air inlet pipe (16), the first molecular sieve dehydration tower (17) is connected to the third-stage compressor (18) through a fourth air inlet pipe (19), the third-stage compressor (18) is connected to the third-stage cooler (20) through a pipeline, the third-stage cooler (20) is connected to the third-stage gas-liquid separator (21) through a pipeline, the third-stage gas-liquid separator (21) is connected to the fourth-stage compressor (22) through a pipeline, the fourth-stage compressor (22) is connected to the fourth-stage cooler (23) through a pipeline. The input end of the exhaust pipe (24) is connected to the fourth-stage cooler (23), one end of the liquid pipe (25) is connected to the liquid buffer tank (26), the other end of the liquid pipe (25) is respectively connected to the cyclone separator (4), the filter separator (5), the first-stage gas-liquid separator (12), the second-stage gas-liquid separator (15) and the first molecular sieve dehydration tower (17), the input end of the discharge pipe (27) is connected to the liquid buffer tank (26), and the output end of the pure CO2 inlet pipe (28) is connected to the gas mixer (9).

2. A high-CO2-containing associated gas reinjection system according to claim 1, characterized in that: A first intake valve (8-1) is installed on the first intake pipe (8).

3. A high-CO2-containing associated gas reinjection system according to claim 1, characterized in that: A second intake valve (16-1) is installed on the second intake pipe (16).

4. A high-CO2-containing associated gas reinjection system according to claim 1, characterized in that: An exhaust valve (24-1) is installed on the exhaust pipe (24).

5. A high-CO2-containing associated gas reinjection system according to claim 1, characterized in that: A liquid discharge valve (27-1) is installed on the liquid discharge pipe (27).

6. A high-CO2-containing associated gas reinjection system according to claim 1, characterized in that: A pure CO2 intake valve (28-1) is installed on the pure CO2 intake pipe (28).

7. A high-CO2-containing associated gas reinjection system according to claim 1, characterized in that: The system further comprises a third air inlet pipe (29) and a second molecular sieve dehydration tower (30); the input end of the third air inlet pipe (29) is connected to the second air inlet pipe (16); the output end of the third air inlet pipe (29) is connected to the air inlet of the second molecular sieve dehydration tower (30); the air outlet of the second molecular sieve dehydration tower (30) is connected to the fourth air inlet pipe (19) via a pipeline; and a third air inlet valve (29-1) is installed on the third air inlet pipe (29).

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