Semi-closed Brayton cycle power generation and oil displacement system and method

Abstract

The invention relates to a power generation and oil displacement system and method based on a Brayton cycle, and aims to improve the crude oil recovery rate, reduce the oil displacement cost and realize efficient power generation. The system comprises a combustion chamber, a turbine, a mechanical energy output device, a water separator and a carbon dioxide compression device. Fuel in the combustion chamber is efficiently combusted under the participation of oxygen to generate a circulating working medium, and the circulating working medium enters the turbine to do work; and the water separator receives the circulating working medium from the outlet of the turbine and separates carbon dioxide and / or water vapor, and then carbon dioxide oil displacement and / or water oil displacement are / is carried out according to the specific condition of the oil reservoir. The carbon dioxide compression device is connected with the water separator, and carbon dioxide which is not discharged to the oil field is compressed by the carbon dioxide compression device and then returns to the combustion chamber to be subjected to semi-closed Brayton cycle.

Description

Technical Field

[0001] The invention relates to the technical field of oil exploitation and power generation, and in particular to a power generation and oil displacement system based on a semi-closed Brayton cycle. Background Art

[0002] Carbon dioxide recovery technology is an important means to improve crude oil recovery. This technology injects carbon dioxide into the oil layer and uses the dissolution and expansion of carbon dioxide to reduce the viscosity of crude oil and increase the fluidity of crude oil, thereby improving the recovery of crude oil. However, although carbon dioxide recovery technology has been widely used in the field of oil extraction, traditional carbon dioxide recovery technology still faces a major challenge, that is, the high cost of obtaining carbon dioxide and the need for specialized production and transportation facilities.

[0003] At the same time, water flooding technology is another common means of improving crude oil recovery. Its principle is relatively simple, the technology is highly mature, and the cost is relatively low. This technology continuously injects water into the oil layer, and with the help of the natural pressure and driving force of water, the crude oil is gradually driven into the production well, thereby achieving effective crude oil extraction. However, water flooding technology has high requirements for the permeability of the reservoir. Once the permeability of the reservoir is poor, the injected water may bypass the crude oil and flow directly to the production well, forming the so-called water channeling phenomenon, which seriously affects the recovery efficiency of crude oil.

[0004] Researchers have been trying to explore a new method to overcome the drawbacks of the above two technologies, reduce costs and further improve efficiency. Using fuel combustion to generate carbon dioxide and water is a promising solution, but how to efficiently generate and utilize these combustion products, avoid waste of resources, and reduce negative impacts on the environment is still an important issue facing current research. Summary of the invention

[0005] In view of the above problems, the present invention provides a power generation and oil recovery system based on a semi-closed Brayton cycle. The system generates power and oil recovery by burning fuel to generate carbon dioxide and water vapor, which can not only significantly improve the oil recovery rate and reduce the cost of carbon dioxide and water oil recovery, but also achieve efficient power generation and improve the overall economy and environmental protection of the system.

[0006] The semi-closed Brayton cycle power generation and oil recovery system provided by the present invention comprises:

[0007] A combustion chamber, used for burning fuel and generating a circulating working medium, wherein the circulating working medium is a mixture of carbon dioxide and water vapor;

[0008] A turbine is connected to the outlet of the combustion chamber, receives the circulating working medium from the outlet of the combustion chamber and performs work;

[0009] A mechanical energy output device is connected to the output end of the turbine and generates energy by using the work done by the turbine;

[0010] A water separator receives the circulating medium from the outlet of the turbine, separates the circulating medium into carbon dioxide, liquid water and / or water vapor through the water separator, and discharges the carbon dioxide, liquid water and / or water vapor to an external oil field through the outlet of the water separator;

[0011] The carbon dioxide compression device is connected to the water separator. The carbon dioxide compression device is used to compress the carbon dioxide that is not discharged to the oil field. The carbon dioxide compressed by the carbon dioxide compression device is returned to the combustion chamber for a semi-closed Brayton cycle.

[0012] According to the technical solution, by combining the semi-closed Brayton cycle power generation and oil recovery system, an efficient and flexible comprehensive solution for oil recovery and power generation is provided, which deepens the depth and breadth of energy utilization. Both carbon dioxide and water vapor have good solubility and diffusion ability, can penetrate into the oil layer, effectively dissolve and displace crude oil, and improve oil recovery efficiency and crude oil recovery rate. The setting of the water separator can be selected and flexibly adjusted in "carbon dioxide oil recovery", "water oil recovery" or "synergy of the two" according to the specific conditions of the reservoir. This flexibility ensures that the system can connect to various complex reservoirs, which not only greatly improves the applicability of the system, but also greatly optimizes the economic cost, and improves the crude oil recovery rate. More importantly, this technical solution generates carbon dioxide through fuel combustion, which can be used for both power generation and oil recovery. It does not require special carbon dioxide production and transportation equipment, and can be "made and used", which is more flexible and practical.

[0013] Preferably, the carbon dioxide in the circulating working fluid at the outlet of the combustion chamber of the semi-closed Brayton cycle power generation and oil recovery system provided by the present invention is supercritical carbon dioxide.

[0014] According to the technical solution, when the carbon dioxide sent out from the combustion chamber is in a supercritical state, the temperature of the turbine inlet can be reduced to a certain extent, thereby reducing the design difficulty and manufacturing cost of the turbine. It not only extends the service life of the turbine, but also improves the overall reliability of the system. Due to its special physical properties, such as low viscosity, good fluidity, and strong diffusivity, supercritical carbon dioxide is easier to penetrate and diffuse in the reservoir than general carbon dioxide, thereby more effectively displacing crude oil from the formation. At the same time, the miscibility pressure of supercritical carbon dioxide and crude oil is low, which means that miscible displacement can be achieved at a lower pressure. The mixed crude oil has a lower viscosity and higher fluidity, which makes it easier to be displaced, thereby improving the oil recovery efficiency. Supercritical carbon dioxide flooding technology is not only applicable to conventional reservoirs, but also to low permeability reservoirs and ultra-low permeability reservoirs. These reservoirs are usually difficult to exploit using traditional methods, and supercritical carbon dioxide flooding technology can significantly improve the recovery rate of these reservoirs.

[0015] Preferably, the semi-closed Brayton cycle power generation and oil recovery system provided by the present invention further includes an air separator connected to the inlet of the combustion chamber, and the air separator separates oxygen from the air and provides it to the combustion chamber.

[0016] According to the technical solution, the high-purity oxygen separated by the air separator is transported to the combustion chamber through the oxygen outlet, providing an oxygen-rich environment for the combustion of the fuel in the combustion chamber, thereby further improving the combustion efficiency of the fuel.

[0017] Preferably, the semi-closed Brayton cycle power generation and oil recovery system provided by the present invention also includes an oil recovery pre-treatment device, the inlet of the oil recovery pre-treatment device is connected to the water separator, and the outlet is connected to the oil field, which is used to adjust the pressure, temperature, and chemical content of carbon dioxide, liquid water and / or water vapor entering the oil field.

[0018] According to the technical solution, the carbon dioxide, liquid water and / or water vapor separated by the water separator pass through the oil flooding pre-treatment device before being sent to the oil field. The function of the oil flooding pre-treatment device is to regulate the pressure, temperature, and chemical agent addition of the carbon dioxide, liquid water and water vapor entering the oil field to ensure that the process parameters of oil flooding are met and the purpose of efficient oil flooding is achieved. The device can store a certain amount of carbon dioxide and water, and can select a variety of oil flooding methods such as carbon dioxide flooding, water flooding, or the synergistic effect of the two according to the on-site working conditions such as geological conditions and process parameters.

[0019] Preferably, the semi-closed Brayton cycle power generation and oil recovery system provided by the present invention also includes a regenerator. After the circulating working fluid output by the turbine and the oxygen separated by the air separator and the carbon dioxide returned to the combustion chamber undergo heat exchange in the regenerator, the oxygen and carbon dioxide enter the combustion chamber.

[0020] According to the technical solution, after being preheated by heat exchange in the regenerator, oxygen and carbon dioxide can reach and maintain a high temperature state more quickly in the subsequent combustion step, reducing heat loss caused by temperature gradient. The efficient combustion step reduces temperature fluctuations in the combustion chamber, making heat distribution more uniform, further improving the thermal efficiency and energy utilization of the system. At the same time, the introduction of the regenerator to recover heat can also flexibly adjust the temperature of the circulating working fluid used for oil recovery, thereby improving the oil recovery effect.

[0021] Preferably, the semi-closed Brayton cycle power generation and oil recovery system provided by the present invention further comprises a multi-way valve, the multi-way valve having a first port, a second port, a third port and a fourth port;

[0022] The water separator includes:

[0023] a first water separator, separating water vapor and carbon dioxide from the circulating working fluid from the regenerator, wherein the water vapor is discharged to an external oil field through a water outlet of the first water separator, and a carbon dioxide outlet of the first water separator is connected to a first port of the multi-way valve;

[0024] a second water separator, cooling the circulating working fluid from the regenerator and separating liquid water and carbon dioxide, wherein the carbon dioxide outlet of the second water separator is connected to the second port of the multi-way valve;

[0025] The third port and the fourth port of the multi-way valve are connected to the carbon dioxide compression device and the oil field respectively.

[0026] According to the technical solution, the carbon dioxide from the first water separator and the second water separator is sent to a carbon dioxide compression device through a multi-way valve for compression and finally returns to the combustion chamber to participate in the circulation, or is sent to a gas injection well in an oil field to participate in the oil recovery step.

[0027] Preferably, the multi-way valve is switched according to the reservoir conditions of the oil field to control the carbon dioxide flow rates of the third port and the fourth port.

[0028] According to the technical solution, the multi-way valve is used to adjust the flow direction of carbon dioxide. According to the specific conditions of the oil field, the carbon dioxide from the first water separator and the second water separator can be selectively diverted from the third port and the fourth port and sent to different directions. Through the cooperation of the multi-way valve and the two water separators, a variety of oil recovery methods such as carbon dioxide recovery, water recovery or the synergy of the two can be selected according to the on-site working conditions of the oil field.

[0029] Preferably, the semi-closed Brayton cycle power generation and oil recovery system provided by the present invention is provided with a gas diverter in the pipe section that returns carbon dioxide from the carbon dioxide compression device to the combustion chamber, and is connected to the outlet of the carbon dioxide compression device. The gas diverter diverts a part of the carbon dioxide compressed by the carbon dioxide compression device out of the semi-closed Brayton cycle to adjust the amount of carbon dioxide in the semi-closed Brayton cycle.

[0030] According to the technical solution, the system can more effectively utilize the compressed carbon dioxide through the gas splitter. When it is necessary to increase power generation or improve oil recovery efficiency, the system can increase the amount of carbon dioxide in the cycle by reducing the amount of carbon dioxide diverted, thereby enhancing the flexibility and reliability of the system. The carbon dioxide diverted from the semi-closed Brayton cycle by the gas splitter has a higher purity, which makes it very suitable for carbon capture technology, thereby improving the overall utilization efficiency of carbon dioxide while optimizing the cycle performance.

[0031] Furthermore, a gas mixer is provided in the pipe section that returns carbon dioxide from the carbon dioxide compression device to the combustion chamber. The gas mixer is connected to the outlet of the gas splitter and the outlet of the air separator respectively. The carbon dioxide sent out through the gas splitter and the oxygen separated by the air separator are first mixed in the gas mixer and then passed into the combustion chamber through the regenerator.

[0032] According to this technical solution, carbon dioxide is mixed with oxygen to form a combustion-supporting stream (ensuring that the concentration of oxygen is within the combustible range), which can further improve the combustion efficiency of the fuel compared to pure oxygen.

[0033] Furthermore, the carbon dioxide compression device used in the semi-closed Brayton cycle power generation and oil recovery system provided by the present invention is a carbon dioxide compression pump.

[0034] According to this technical solution, the carbon dioxide compression pump further reduces the equipment requirements compared to traditional carbon dioxide compressors, so that the compression equipment does not need to operate near the critical point, ensuring the high efficiency and long-term stable operation of the cycle, and reducing the number of equipment shutdowns and maintenance times.

[0035] Furthermore, the combustion chamber used in the present system is a high pressure combustion chamber.

[0036] According to this technical solution, under high pressure environment, the flame temperature can be increased, the radiation coefficient can be enhanced, thereby enhancing the combustion intensity, increasing the heat transfer efficiency, and improving, thereby making fuller use of the chemical energy in the fuel. This not only improves the calorific value utilization of the fuel and avoids energy waste, but also reduces the emission of harmful gases such as carbon monoxide and unburned fuel produced by incomplete combustion, which is in line with the environmental protection concept of energy conservation and emission reduction.

[0037] Furthermore, based on the efficient combustion environment provided by the high-pressure combustion chamber, the fuel used by the system may be natural gas, liquefied petroleum gas and / or gasified gas.

[0038] According to this technical solution, the diversified fuel selection enables the solution to be widely used in various environments. This makes the system extremely flexible. Different regions can choose the appropriate fuel according to their own resource conditions and needs.

[0039] The present invention also provides a semi-closed Brayton cycle power generation and oil recovery method, comprising the following steps:

[0040] A combustion step, in which the fuel is burned in the combustion chamber to generate a circulating working medium, wherein the circulating working medium is a mixture of carbon dioxide and water vapor;

[0041] In a working step, the turbine receives the circulating working fluid from the outlet of the combustion chamber and performs work;

[0042] In the oil recovery step, the circulating working fluid is separated into carbon dioxide, liquid water and / or water vapor via a water separator, and the carbon dioxide, liquid water and / or water vapor are discharged to an external oil field via an outlet of the water separator to perform a carbon dioxide oil recovery and / or water oil recovery operation;

[0043] In the compression cycle step, the carbon dioxide that is not discharged to the oil field is compressed by a carbon dioxide compression device to obtain compressed carbon dioxide, and then returned to the combustion chamber to perform a semi-closed Brayton cycle.

[0044] Preferably, the semi-closed Brayton cycle power generation and oil recovery method provided by the present invention also includes a heat recovery step, wherein oxygen, compressed carbon dioxide and fuel are heat exchanged with the circulating working fluid in the regenerator before entering the combustion chamber to participate in combustion. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a structural schematic diagram of a semi-closed Brayton cycle power generation and oil recovery system according to a first embodiment of the present invention;

[0046] Figure 2 It is a structural schematic diagram of a semi-closed Brayton cycle power generation and oil recovery system according to a second embodiment of the present invention;

[0047] Figure 3 Flow chart of the semi-closed Brayton cycle power generation and oil recovery method according to the first and second embodiments of the present invention.

[0048] Reference numerals:

[0049] Turbine 1; regenerator 2; first water separator 12; second water separator 3; multi-way valve 4; gas diverter 6; first circulation pump 5; second circulation pump 8; gas mixer 7; air separator 9; combustion chamber 10; mechanical energy output device 11; oil field 14; oil displacement pre-treatment device 13. DETAILED DESCRIPTION

[0050] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] [First embodiment]

[0052] See also Figure 1 Shown is a schematic diagram of a semi-closed Brayton cycle power generation and oil recovery system according to an embodiment of the present invention.

[0053] In this embodiment, the power generation and oil recovery system includes: a turbine 1, a regenerator 2, a first water separator 12, a second water separator 3, a multi-way valve 4, a first circulation pump 5, a gas diverter 6, a gas mixer 7, a second circulation pump 8, an air separator 9, a combustion chamber 10, a mechanical energy output device 11 and an oil recovery pre-treatment device 13.

[0054] The combustion chamber 10 has a fuel inlet, an oxygen inlet, a first circulating medium outlet, and a separation return port. Fuel and oxygen enter the combustion chamber 10 from the fuel inlet and the oxygen inlet respectively, and are burned in the combustion chamber 10 to generate high-temperature and high-pressure circulating medium (main components are carbon dioxide and water vapor). These high-temperature and high-pressure circulating mediums are output from the first circulating medium outlet and sent to the turbine 1.

[0055] The turbine 1 has a circulating medium inlet, a second circulating medium outlet and a mechanical energy output terminal. The circulating medium inlet of the turbine 1 is connected to the first circulating medium outlet of the combustion chamber 10. The function of the turbine 1 is to convert the heat energy of the circulating medium (mainly carbon dioxide and water vapor) generated by the combustion of fuel in the combustion chamber 10 into mechanical energy by doing work.

[0056] The mechanical energy output end of the turbine 1 is connected to a mechanical energy output device 11, and the mechanical energy output device 11 converts the mechanical energy output by the turbine into electrical energy and / or kinetic energy.

[0057] In some embodiments, the mechanical energy output device may be a generator.

[0058] The regenerator 2 includes a first circulating medium flow channel, a second circulating flow channel, and a third air flow channel. The circulating medium (mainly carbon dioxide and water vapor) output from the turbine 1 enters the first circulating medium flow channel of the regenerator 2 to provide heat for the regenerator; the inlet of the second circulating flow channel is connected to the outlet of the second circulating pump 8, and the outlet of the second circulating flow channel is connected to the separation return port of the combustion chamber 10, which is used to provide combustion-supporting gas for the circulation; the inlet of the third air flow channel is connected to an outlet of the air separator 9, and the outlet of the third air flow channel is connected to the oxygen inlet of the combustion chamber 10, which is used to provide preheated oxygen for the combustion chamber 10. The function of the regenerator 2 is to transfer the heat of the circulating medium in the first circulating medium flow channel to the medium entering the second circulating flow channel and the oxygen in the third air flow channel through heat exchange.

[0059] After the circulating working fluid output by the turbine 1 enters the first circulating working fluid flow channel inlet of the self-heat regenerator 2, it is divided into a first flow stream and a second flow stream at the outlet of the first circulating working fluid flow channel, wherein the first flow stream flows into the first water separator 12, and the second flow stream flows into the second water separator 3.

[0060] The first water separator 12 is provided with a first separation port and a second separation port. The first water separator 12 separates the carbon dioxide and water vapor in the circulating working fluid of the first stream by membrane separation or adsorption separation, wherein the water vapor is sent to the oil field through the first separation port and discharged.

[0061] The second water separator 3 cools the circulating working fluid of the second stream and separates it into carbon dioxide and liquid water. The separated liquid water is discharged through the water outlet of the second water separator 3, and the separated carbon dioxide is sent to the oil field or to the first circulation pump 5 for compression through the outlet of the second water separator 3 via the multi-way valve 4 and finally returns to the combustion chamber 10 to participate in the circulation.

[0062] The carbon dioxide flowing out of the second separation port of the first water separator 12 and the outlet of the second water separator 3 is uniformly collected in the multi-way valve 4. The multi-way valve 4 has a first port, a second port, a third port and a fourth port. The second separation port of the first water separator 12 is connected to the first port of the multi-way valve 4; the outlet of the second water separator 3 is connected to the second port of the multi-way valve; the third port and the fourth port of the multi-way valve are respectively connected to the first circulation pump 5 and the oil field 14. When water drive oil is adopted, the carbon dioxide separated from the two water separators is no longer discharged to the oil field, but is discharged to the first circulation pump 5 through the multi-way valve 4, compressed by the first circulation pump 5, and then circulated back to the combustion chamber 10, and enters from the separation return port of the combustion chamber 10, so as to realize the stable flow of the semi-closed Brayton cycle. The function of the multi-way valve 4 is to adjust the flow direction of carbon dioxide, and the carbon dioxide from the first water separator 12 and the second water separator 3 can be selectively sent to the first circulation pump 5 for compression and finally returned to the combustion chamber 10 to participate in the circulation, or sent to the gas injection well of the oil field 14 to participate in the oil drive step.

[0063] Optionally, the semi-closed Brayton cycle power generation and oil recovery system of this embodiment further includes an oil recovery pre-treatment device 13, the two inlets of the oil recovery pre-treatment device 13 are respectively connected to the second separation port of the first water separator 12 and the fourth port of the multi-way valve 4, and the only outlet is connected to the oil field. The function of the oil recovery pre-treatment device 13 is to adjust the pressure, temperature, and chemical content of the carbon dioxide and / or water entering the oil field to ensure the optimal oil recovery process parameters.

[0064] Optionally, the first circulation pump 5 and the combustion chamber 10 of the semi-closed Brayton cycle power generation and oil recovery system of this embodiment are indirectly connected to achieve the circulation of compressed carbon dioxide through a series of components. These components specifically include: a gas splitter 6, a gas mixer 7, a second circulation pump 8 and an air separator 9.

[0065] The inlet of the gas diverter 6 is connected to the outlet of the first circulation pump 5, and is used to divert and purify the compressed working medium (mainly carbon dioxide) to adjust the working medium content in the Brayton cycle system. The working medium (carbon dioxide) diverted and purified by the gas diverter 6 enters the gas mixer 7, and is mixed with the oxygen sent by the air separator 9 to form a combustion-supporting gas. The combustion-supporting gas is preheated by the regenerator 2 and enters the separation return port of the combustion chamber 10 to participate in the semi-closed Brayton cycle. The carbon dioxide in the part of the working medium diverted from the circulation system by the gas diverter 6 has a higher purity and can also be used for carbon capture.

[0066] The inlet of the air separator 9 is connected to the outside atmosphere, and the two outlets are respectively connected to the inlet of the third air flow channel of the regenerator 2 and the inlet of the gas mixer 7. Pure oxygen can be obtained after the outside air is separated by the air separator 9. Part of the pure oxygen is sent to the gas mixer 7 and mixed with the working medium (carbon dioxide) after diversion and purification by the gas diverter 6 to form a combustion-supporting flow stream, and the other part is preheated by the regenerator 2 and sent to the oxygen inlet of the combustion chamber 10, providing pure oxygen for fuel combustion, thereby ensuring the efficient and clean combustion step.

[0067] Through the above methods, the semi-closed Brayton cycle power generation and oil recovery system provided by this embodiment utilizes the excellent solubility and expansion of supercritical carbon dioxide to enhance the oil recovery effect and improve the crude oil recovery rate, especially when treating low permeability and heavy oil reservoirs. At the same time, the semi-closed Brayton cycle power generation and oil recovery system provided by this embodiment also overcomes the disadvantages of high carbon dioxide acquisition costs and the need for special production and transportation facilities in traditional carbon dioxide oil recovery operations. In addition, the design of the water separator allows flexible selection of oil recovery modes according to reservoir characteristics, effectively optimizing costs and improving recovery efficiency. At the same time, the use of the supercritical state can also reduce the turbine inlet temperature, simplify the turbine design, reduce manufacturing costs, extend service life, and further improve the reliability of the entire system.

[0068] [Second embodiment]

[0069] The structural schematic diagram of the semi-closed Brayton cycle power generation and oil recovery system and method in the second embodiment provided by the present invention is as follows Figure 2 As shown. It is basically the same as the semi-closed Brayton cycle power generation and oil recovery system structure in the first embodiment, the difference is that the first water separator 12 is omitted in this embodiment, simplifying the system structure. That is, after the circulating working fluid output from the turbine 1 enters the first circulating working fluid flow channel inlet of the self-regenerator 2, it does not split at the outlet of the first circulating working fluid flow channel, and all flows into the second water separator 3. The second water separator 3 cools the circulating working fluid and separates liquid water and carbon dioxide. The carbon dioxide outlet of the second water separator 3 is connected to the second port of the multi-way valve; the drainage outlet of the second water separator 3 leads to the oil field.

[0070] The first and second embodiments together provide a semi-closed Brayton cycle power generation and oil recovery method, referring to Figure 3 , the power generation and oil recovery method comprises the following steps:

[0071] Combustion step, the fuel is burned in the combustion chamber 10 to generate a circulating working medium, the circulating working medium is a mixture of carbon dioxide and water vapor;

[0072] In the working step, the turbine 1 receives the circulating medium from the outlet of the combustion chamber 10 and performs work;

[0073] In the reheating step, oxygen and compressed carbon dioxide are heat exchanged with the circulating working fluid in the reheater 2 before entering the combustion chamber 10 to participate in combustion;

[0074] In the oil recovery step, the circulating medium is separated into carbon dioxide, liquid water and / or water vapor via the water separator 3, 12, and the carbon dioxide, liquid water and / or water vapor are discharged to the external oil field 14 via the outlet of the water separator 3, 12 to perform carbon dioxide oil recovery and / or water oil recovery operations;

[0075] In the compression cycle step, the supercritical carbon dioxide that is not discharged to the oil field 14 is compressed, and then processed by a series of equipment, and finally a part of it is returned to the combustion chamber 10 for the semi-closed Brayton cycle.

[0076] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A semi-closed Brayton cycle power generation and oil recovery system, characterized in that: include: A combustion chamber, used for burning fuel and generating a circulating working medium, wherein the circulating working medium is a mixture of carbon dioxide and water vapor; a turbine, connected to the outlet of the combustion chamber, receiving the circulating working medium from the outlet of the combustion chamber and performing work; A mechanical energy output device connected to the output end of the turbine and utilizing the turbine to generate energy; a water separator, receiving the circulating medium from the outlet of the turbine, separating carbon dioxide, liquid water and / or water vapor from the circulating medium through the water separator, and discharging the carbon dioxide, liquid water and / or water vapor to an external oil field through the outlet of the water separator; A carbon dioxide compression device is connected to the water separator, and is used to compress the carbon dioxide that has not been discharged to the oil field. The carbon dioxide compressed by the carbon dioxide compression device is returned to the combustion chamber to perform the semi-closed Brayton cycle.

2. The semi-closed Brayton cycle power generation and oil recovery system according to claim 1, characterized in that: The working fluid generated by the combustion of fuel in the combustion chamber is a mixture of carbon dioxide and water vapor.

3. The semi-closed Brayton cycle power generation and oil recovery system according to claim 1, characterized in that: The combustion chamber further includes an air separator which is in communication with an inlet of the combustion chamber. The air separator separates oxygen from air and provides the oxygen to the combustion chamber.

4. The semi-closed Brayton cycle power generation and oil recovery system according to claim 1, characterized in that: It also includes an oil recovery pre-treatment device, the inlet of which is connected to the water separator, and the outlet of which is connected to the oil field, and is used to adjust one or more of the pressure, temperature, and chemical content of carbon dioxide, liquid water, and / or water vapor entering the oil field.

5. The semi-closed Brayton cycle power generation and oil recovery system according to claim 3, characterized in that: It also includes a regenerator. After the circulating working fluid output by the turbine, the oxygen separated by the air separator, and the carbon dioxide returned to the combustion chamber undergo heat exchange in the regenerator, the oxygen and the carbon dioxide enter the combustion chamber.

6. The semi-closed Brayton cycle power generation and oil recovery system according to claim 5, characterized in that: Also includes: a multi-way valve having a first port, a second port, a third port, and a fourth port; The water separator comprises: a first water separator, separating water vapor and carbon dioxide from the circulating working fluid from the regenerator, wherein the water vapor is discharged to an external oil field via a water outlet of the first water separator, and the carbon dioxide outlet of the first water separator is connected to the first port of the multi-way valve; a second water separator, cooling the circulating working fluid from the regenerator and separating liquid water and carbon dioxide, wherein the carbon dioxide outlet of the second water separator is connected to the second port of the multi-way valve; The third port and the fourth port of the multi-way valve are connected to the carbon dioxide compression device and the oil field, respectively.

7. The semi-closed Brayton cycle power generation and oil recovery system according to claim 6, characterized in that: The multi-way valve switches according to the reservoir conditions of the oil field to control the carbon dioxide flow of the third port and the fourth port.

8. The semi-closed Brayton cycle power generation and oil recovery system according to claim 6, characterized in that: A gas diverter is provided in the pipe section returning carbon dioxide from the carbon dioxide compression device to the combustion chamber and is connected to the outlet of the carbon dioxide compression device. The gas diverter diverts a portion of the carbon dioxide compressed by the carbon dioxide compression device out of the semi-closed Brayton cycle to adjust the amount of carbon dioxide in the semi-closed Brayton cycle.

9. A semi-closed Brayton cycle power generation and oil recovery method, characterized in that: The following steps are involved: A combustion step, in which the fuel is burned in the combustion chamber to generate a circulating working medium, wherein the circulating working medium is a mixture of carbon dioxide and water vapor; a working step, wherein the turbine receives the circulating working medium from the outlet of the combustion chamber and performs work; an oil recovery step, wherein the circulating working fluid is separated into carbon dioxide, liquid water and / or water vapor via a water separator, and the carbon dioxide, liquid water and / or water vapor are discharged to an external oil field via an outlet of the water separator to perform a carbon dioxide oil recovery and / or water oil recovery operation; In the compression cycle step, the carbon dioxide that has not been discharged to the oil field is compressed by a carbon dioxide compression device to obtain compressed carbon dioxide, and then returned to the combustion chamber to perform the semi-closed Brayton cycle.

10. The semi-closed Brayton cycle power generation and oil recovery method according to claim 9, characterized in that: It also includes a heat recovery step, in which oxygen, compressed carbon dioxide and fuel are heat exchanged with the circulating working fluid in the heat regenerator before entering the combustion chamber to participate in combustion.

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