A system and method for solvent closed cycle separation and reinjection

Abstract

This invention provides a system and method for closed-loop solvent separation and reinjection. The system includes: a primary separator, a secondary separator, a primary gas container, a secondary gas container, a crude oil collection container, and a piston-type gas collector. The method includes: introducing a mixture containing crude oil and solvent into the primary separator for separation; discharging gaseous solvent from the primary separator into the primary gas container, discharging the liquid mixture from the primary separator into the secondary separator for separation; discharging gaseous solvent from the secondary separator into the secondary gas container, discharging the liquid mixture from the secondary separator into the crude oil collection container; and injecting the gaseous solvent discharged from the primary and secondary gas containers into the piston-type gas collector, where it is then pressurized, liquefied, and reinjected into the oil reservoir. This system and method achieve closed-loop solvent separation and reinjection during the extraction of heavy and extra-heavy oil, thereby improving oil recovery.

Description

Technical Field

[0001] This invention relates to a system and method for closed-loop solvent separation and reinjection, belonging to the field of petroleum extraction. Background Technology

[0002] Shallow extra-heavy oil reservoirs exhibit high viscosity and poor flowability in high-temperature zones, making steam viscosity reduction alone ineffective. In some areas, extra-heavy oil viscosity can reach 60-100 mPa·s under steam-induced high-temperature conditions (200℃). Since crude oil viscosity directly affects oil flowability and production rate, conventional steam injection methods result in low yields for extra-heavy oil. Therefore, exploring new composite extraction technologies to further reduce crude oil viscosity beyond conventional steam injection is urgently needed for both heavy and extra-heavy oil reservoirs.

[0003] Studies have shown that adding a small amount of light hydrocarbon solvent to steam can accelerate viscosity reduction, lowering crude oil viscosity to below 5 mPa·s under steam chamber conditions. This represents a new approach to significantly increase the production and recovery rate of heavy and extra-heavy oils. However, light hydrocarbon solvents are expensive and require recycling and reinjection to be economically viable. Currently, there are few devices and methods available for solvent reinjection. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a system and method for closed-loop solvent separation and reinjection. The system and method of the present invention can achieve closed-loop solvent separation and reinjection during the solvent development process of heavy and extra-heavy oil reservoirs, thereby improving oil recovery.

[0005] The present invention also aims to provide an experimental system and method for solvent closed-loop circulation separation and reinjection. The experimental system of the present invention is a simulation experimental system for solvent injection exploitation in heavy and extra-heavy oil reservoirs, capable of simulating solvent closed-loop circulation separation and reinjection.

[0006] To achieve the above objectives, the first aspect of the present invention provides a system for closed-loop solvent separation and reinjection, comprising: a primary separator, a secondary separator, a primary gas container, a secondary gas container, a crude oil collection container, and a piston-type gas collector;

[0007] The primary separator includes at least an injection port, a liquid outlet, a gas outlet, a first injection mechanism, a first gas / liquid interface probe, and a first pressure sensor. The injection port and the liquid outlet are located at the bottom of the primary separator; the gas outlet is located at the top of the primary separator; the first injection mechanism is located inside the cavity of the primary separator and communicates with the injection port; the first gas / liquid interface probe is located inside the cavity of the primary separator; and the first pressure sensor is located on a pipeline communicating with the gas outlet for detecting the pressure inside the primary separator.

[0008] The secondary separator is provided with at least an injection port, a liquid outlet, a gas outlet, a second injection mechanism, a second gas / liquid interface probe, and a second pressure sensor; the injection port and the liquid outlet are located at the bottom of the secondary separator; the gas outlet is located at the top of the secondary separator; the second injection mechanism is located inside the cavity of the secondary separator and communicates with the injection port; the second gas / liquid interface probe is located inside the cavity of the secondary separator; the second pressure sensor is located on a pipeline communicating with the gas outlet and is used to detect the pressure inside the secondary separator.

[0009] The primary gas container is provided with at least an injection port and an exhaust port;

[0010] The secondary gas container is provided with at least an injection port and an exhaust port;

[0011] The piston-type gas collector is provided with at least an injection port, an outlet, a discharge pipeline, a piston, and a third pressure sensor; the injection port is located at the bottom of the piston-type gas collector; the outlet is located at the top of the piston-type gas collector; the discharge pipeline is located inside the cavity of the piston-type gas collector and communicates with the outlet; the piston is located inside the cavity of the piston-type gas collector; the third pressure sensor is located on the pipeline communicating with the outlet and is used to detect the pressure inside the piston-type gas collector.

[0012] The inlet of the primary separator is used to allow a mixture containing crude oil and solvent to enter the primary separator;

[0013] The liquid outlet of the primary separator is connected to the inlet of the secondary separator via a pipeline;

[0014] The gas outlet of the primary separator is connected to the inlet of the primary gas container via a pipeline;

[0015] The gas outlet of the secondary separator is connected to the inlet of the secondary gas container via a pipeline;

[0016] The outlet of the primary gas container and the outlet of the secondary gas container are connected to the inlet of the piston-type gas collector via pipelines.

[0017] The crude oil collection container is connected to the liquid outlet of the secondary separator via a pipeline.

[0018] In the above system, the primary separator is used to achieve pressurized primary separation of the solvent in the mixture containing crude oil and solvent. The secondary separator is used to achieve pressurized or unpressurized secondary separation of the solvent in the mixture containing crude oil and solvent obtained after a portion of the solvent has been separated by the primary separator. The primary gas container is used to collect the gaseous solvent separated by the primary separator. The secondary gas container is used to collect the gaseous solvent separated by the secondary separator. The piston-type gas collector is used to collect the gaseous solvent from the primary and secondary gas containers, and after remixing, it is used for reinjection. The crude oil collection container is used to collect the mixture containing crude oil obtained by sequential separation by the primary and secondary separators.

[0019] According to a specific embodiment of the present invention, preferably, the system further includes a data acquisition and processing device, which is communicatively connected to a first gas / liquid interface probe, a second gas / liquid interface probe, a first pressure sensor, a second pressure sensor, and a third pressure sensor, for collecting, monitoring, and processing data detected by the gas / liquid interface probes and pressure sensors. Generally, the data acquisition and processing device may include devices such as a data acquisition unit and a computer. The communication connection may include an electrical connection.

[0020] In the above system, preferably, valves are installed on the pipelines connecting the liquid outlet and the gas outlet of the primary separator.

[0021] In the above system, preferably, one end of the first injection mechanism is connected to the injection port of the primary separator, and the other end has an injection port. The first injection mechanism is used to inject the mixture containing crude oil and solvent into the primary separator from bottom to top. More preferably, the first injection mechanism is arranged perpendicular to the bottom surface of the primary separator.

[0022] In the above system, preferably, the length of the first injection mechanism is 1 / 2 to 2 / 3 of the height of the inner cavity of the primary separator.

[0023] In the above system, preferably, the first gas / liquid interface probe is a resistance probe.

[0024] In the above system, preferably, the first gas / liquid interface probe is arranged in parallel with the first injection mechanism.

[0025] In the above system, preferably, the height of the first gas / liquid interface probe is 1 / 2 to 3 / 4 of the height of the inner cavity of the first-stage separator.

[0026] In the above system, preferably, valves are installed on the pipelines connecting the liquid outlet and the gas outlet of the secondary separator.

[0027] In the above system, preferably, one end of the second injection mechanism is connected to the injection port of the secondary separator, and the other end has an injection port. The second injection mechanism is used to inject the mixture containing crude oil and solvent, obtained after a portion of the solvent is separated in the primary separator, into the secondary separator from bottom to top. More preferably, the second injection mechanism is arranged perpendicular to the bottom surface of the secondary separator.

[0028] In the above system, preferably, the length of the second injection mechanism is 1 / 2 to 2 / 3 of the height of the inner cavity of the secondary separator.

[0029] In the above system, preferably, the second gas / liquid interface probe is a resistance probe.

[0030] In the above system, preferably, the second gas / liquid interface probe is arranged in parallel with the second injection mechanism.

[0031] In the above system, preferably, the height of the second gas / liquid interface probe is 1 / 2 to 3 / 4 of the height of the inner cavity of the secondary separator.

[0032] This invention incorporates gas / liquid interface probes in both the primary and secondary separators to detect the gas-liquid interface. Utilizing the difference in resistivity between the gas and liquid, this difference is fed back to the control software in the data acquisition and processing device, enabling real-time monitoring and determination of the gas-liquid interface. Once the gas / liquid interface probes detect it, liquid can be drained through the liquid outlets of the primary and secondary separators to control the gas / liquid interface height within a suitable range, preventing liquid accumulation or overflow in the separators and preventing gas escape from the liquid outlet at the bottom of the separators.

[0033] In the above system, preferably, a heating jacket is provided on the outside of the secondary separator. A heating jacket conventional in the art can be used to heat the secondary separator to the required temperature.

[0034] In the above system, preferably, a first gas mass flow controller is provided on the pipeline connecting the first-stage separator and the first-stage gas container, which is at least used to measure the flow rate of the gaseous solvent separated by the first-stage separator.

[0035] In the above system, preferably, a second gas mass flow controller is provided on the pipeline connecting the secondary separator and the secondary gas container, which is at least used to measure the flow rate of the gaseous solvent separated by the secondary separator.

[0036] In the above system, preferably, the piston-type gas collector has two injection ports, which are respectively connected to the outlet of the primary gas container and the outlet of the secondary gas container via pipelines.

[0037] In the above system, preferably, a valve is provided on the pipeline connected to the injection port of the piston-type gas collector.

[0038] In the above system, preferably, when the gaseous solvent from the primary gas container and the secondary gas container is injected into the piston-type gas collector, it pushes the piston located at the bottom of the inner cavity of the piston-type gas collector to move upward. The piston divides the cavity of the piston-type gas collector into a pressure regulating chamber above the piston and a solvent chamber below the piston. Those skilled in the art will understand that one end of the discharge line in the piston-type gas collector should extend into the solvent chamber, and the other end of the discharge line should be connected to the discharge port of the piston-type gas collector.

[0039] In the above system, preferably, the piston-type gas collector is further provided with a pressure regulating valve, which is located at the top of the piston-type gas collector, and is used to regulate the pressure in the solvent chamber through the pressure regulating chamber using the pressure regulating valve.

[0040] In the above system, preferably, a compressor is provided on the pipeline connected to the outlet of the piston gas collector to pressurize the solvent to the injection pressure.

[0041] In the above system, preferably, a third gas mass flow controller is installed on the pipeline connected to the outlet of the piston-type gas collector, at least for measuring the flow rate of the reinjected solvent. More preferably, the third gas mass flow controller is located downstream of the compressor.

[0042] According to a specific embodiment of the present invention, preferably, the above system further includes: a weighing device for weighing the weight of the mixture containing crude oil in the crude oil collection container.

[0043] A second aspect of the present invention provides an experimental system for closed-loop solvent separation and reinjection, the experimental system comprising the aforementioned closed-loop solvent separation and reinjection system, and an experimental model; the experimental model is provided with at least an injection port and an outlet port, the injection port being located at the top of the experimental model and the outlet port being located at the bottom of the experimental model; the outlet port of the experimental model is connected to the injection port of the primary separator via a pipeline; the injection port of the experimental model is connected to the outlet port of the piston-type gas collector via a pipeline.

[0044] According to a specific embodiment of the present invention, the experimental model can employ a high-temperature, high-pressure gas-liquid separator. This high-temperature, high-pressure gas-liquid separator can be a conventional device in the art, and the present invention does not impose any specific limitations on its structure.

[0045] In the above-described experimental system, preferably, valves are installed on the pipelines connecting the injection port and the discharge port of the experimental model to control the injection of solvent and the discharge of the mixture containing crude oil and solvent.

[0046] In the above-described experimental system, preferably, a compressor and a third gas mass flow controller are installed on the pipeline connecting the injection port of the experimental model to the discharge port of the piston-type gas collector.

[0047] A third aspect of the present invention provides a method for solvent closed-loop separation and reinjection, the method employing the aforementioned solvent closed-loop separation and reinjection system, the method comprising the following steps:

[0048] (1) The mixture system containing crude oil and solvent produced by the reservoir is brought into the first-stage separator, the gas-liquid interface is monitored in real time using the first gas / liquid interface probe, and the pressure in the first-stage separator is made to reach P1.

[0049] (2) After the pressure in the first-stage separator reaches P1, the gaseous solvent is discharged from the top of the first-stage separator and enters the first-stage gas container, and the mixture containing crude oil and solvent is discharged from the bottom of the first-stage separator and enters the second-stage separator.

[0050] (3) The gas-liquid interface in the secondary separator is monitored in real time using the second gas / liquid interface probe. When the gas-liquid interface in the secondary separator reaches more than 1 / 3 of the height of the secondary separator cavity, the gaseous solvent is discharged from the top of the secondary separator and enters the secondary gas container, and the mixed system containing crude oil is discharged from the bottom of the secondary separator and enters the crude oil collection container. The pressure in the secondary separator is P2.

[0051] (4) Adjust the pressure inside the piston gas collector in real time so that the gaseous solvent discharged from the primary gas container and the secondary gas container can enter the piston gas collector.

[0052] (5) After pressurizing and liquefying the gaseous solvent discharged from the piston gas collector, it is reinjected into the reservoir.

[0053] In the above method, preferably, the solvent includes one or a combination of several of the following: light alkanes of C1-C10, light aromatics of C6-C10, alcohols of less than C10, aldehydes of less than C10, ethers of less than C10, and ketones of less than C10.

[0054] In the above method, preferably, in step (1), the gas / liquid interface is monitored in real time using a first gas / liquid interface probe to control the height of the gas / liquid interface to be less than 1 / 5 of the height of the inner cavity of the first-stage separator.

[0055] In the above method, preferably, in step (1), the pressure P1 in the primary separator is 0.5 to 1 MPa below the solvent saturated vapor pressure under the temperature conditions in the primary separator.

[0056] In the above method, preferably, in step (1), the temperature inside the primary separator is above the highest flash point temperature of one or more combinations of C1-C5 light alkanes, alcohols below C5, aldehydes below C5, ethers below C5, and ketones below C5. More preferably, the temperature inside the primary separator is 20-30°C.

[0057] In the above method, preferably, in step (3), the pressure P2 in the secondary separator is atmospheric pressure or 0.5 to 1 MPa below the solvent saturated vapor pressure under the temperature conditions in the secondary separator.

[0058] In the above method, preferably, in step (3), the temperature in the secondary separator is above the highest flash point temperature of one or more of the following: light alkanes of C6-C10, light aromatics of C6-C10, alcohols of C6-C10, aldehydes of C6-C10, ethers of C6-C10, and ketones of C6-C10.

[0059] According to a specific embodiment of the present invention, a primary separator is used to separate solvents with C5 or less, and a secondary separator is used to separate solvents with C6-C10.

[0060] According to a specific embodiment of the present invention, the pressure inside the first and second separators can be detected in real time by using the first and second pressure sensors installed at the top of the first and second separators, and the pressure inside the first and second separators can be controlled and adjusted in real time by using the valves installed on the pipelines connected to the gas outlets at the top of the first and second separators to achieve dynamic pressure balance.

[0061] In the above method, preferably, in step (2), the gaseous solvent discharged from the top of the primary separator is metered to a flow rate of Q1 by the first gas mass flow controller and then enters the primary gas container.

[0062] In the above method, preferably, in step (3), the gaseous solvent discharged from the top of the secondary separator is metered to a flow rate of Q2 by the second gas mass flow controller and then enters the secondary gas container.

[0063] In the above method, preferably, in step (4), the pressure of the solvent chamber of the piston gas collector is adjusted in real time by the pressure regulating valve at the top of the piston gas collector, and the gaseous solvent discharged from the primary gas container and the secondary gas container enters the solvent chamber of the piston gas collector.

[0064] In the above method, preferably, in step (5), the gaseous solvent discharged from the piston gas collector is pressurized and liquefied by a compressor, and then the liquid solvent is re-injected into the reservoir after the flow rate is measured to Q3 by a third gas mass flow controller.

[0065] In the above method, preferably, in step (5), the pressure of the solvent after pressurizing and liquefying the gaseous solvent discharged from the piston gas collector by the compressor is 0.5-1.0 MPa above the saturated vapor pressure of the solvent. The pressure of the solvent after pressurization and liquefaction is the injection pressure.

[0066] According to a specific embodiment of the present invention, preferably, the above method further includes step (6): calculating the real-time solvent reinjection rate by real-time monitoring Q1, Q2, and Q3, where solvent reinjection rate = (Q1 + Q2) × 100% / Q3. In the present invention, solvent reinjection rate is also known as solvent recovery rate.

[0067] In the above method, preferably, the pressure in the solvent chamber of the piston gas collector is less than or equal to the pressure in the primary gas container and the secondary gas container.

[0068] In the above method, preferably, the pressure in the solvent chamber of the piston gas collector is less than or equal to the outlet pressure of the compressor.

[0069] According to a specific embodiment of the present invention, in the above method, the pressure in the solvent chamber of the piston-type gas collector is P5, the pressure in the primary gas container is P3, and the pressure in the secondary gas container is P4. To ensure that the gaseous containers in both the primary and secondary gas containers can enter the piston-type gas collector, P5 needs to be controlled to be less than or equal to P3 and P4. Simultaneously, the compressor outlet pressure is P7. To ensure that the gaseous solvent in the piston-type gas collector can enter the compressor, the compressor outlet pressure P7 needs to be controlled to be greater than or equal to the pressure P5 in the solvent chamber of the piston-type gas collector (this pressure is also the compressor inlet pressure). The pressure P5 in the solvent chamber of the piston-type gas collector needs to be adjusted to simultaneously satisfy the above conditions, i.e., P5 must be less than or equal to P3, P4, and P7. The pressure P5 in the solvent chamber of the piston-type gas collector is controlled by a pressure regulating valve at the top of the piston-type gas collector. The pressure regulating valve adjusts the pressure P6 in the upper pressure regulating chamber in a timely manner by releasing gas, so that P5 simultaneously satisfies the above conditions. By adjusting the pressure P5 in the solvent chamber of the piston-type gas collector in real time, dynamic balance control and mixing of the gaseous solvent before reinjection can be achieved.

[0070] According to a specific embodiment of the present invention, preferably, the above method further includes step (7): weighing the weight of the mixture containing crude oil in the crude oil collection container in real time using a weighing device.

[0071] A fourth aspect of the present invention provides an experimental method for solvent closed-loop separation and reinjection, the method employing the aforementioned experimental system for solvent closed-loop separation and reinjection, and the method comprising the following steps:

[0072] (1) The mixture system containing crude oil and solvent in the experimental model is introduced into the first-stage separator. The gas-liquid interface is monitored in real time using the first gas / liquid interface probe, and the pressure in the first-stage separator is made to reach P1.

[0073] (2) After the pressure in the first-stage separator reaches P1, the gaseous solvent is discharged from the top of the first-stage separator and enters the first-stage gas container, and the mixture containing crude oil and solvent is discharged from the bottom of the first-stage separator and enters the second-stage separator.

[0074] (3) The gas-liquid interface in the secondary separator is monitored in real time using the second gas / liquid interface probe. When the gas-liquid interface in the secondary separator reaches more than 1 / 3 of the height of the secondary separator cavity, the gaseous solvent is discharged from the top of the secondary separator and enters the secondary gas container, and the mixed system containing crude oil is discharged from the bottom of the secondary separator and enters the crude oil collection container. The pressure in the secondary separator is P2.

[0075] (4) Adjust the pressure inside the piston gas collector in real time so that the gaseous solvent discharged from the primary gas container and the secondary gas container can enter the piston gas collector.

[0076] (5) After pressurizing and liquefying the gaseous solvent discharged from the piston gas collector, it is re-injected into the experimental model.

[0077] In the above experimental method, preferably, the solvent includes one or a combination of several of the following: light alkanes of C1-C10, light aromatics of C6-C10, alcohols below C10, aldehydes below C10, ethers below C10, and ketones below C10.

[0078] In the above experimental method, preferably, in step (1), the gas / liquid interface is monitored in real time using a first gas / liquid interface probe to control the height of the gas / liquid interface to be less than 1 / 5 of the height of the inner cavity of the first-stage separator.

[0079] In the above experimental method, preferably, in step (1), the pressure P1 in the primary separator is 0.5 to 1 MPa below the solvent saturated vapor pressure under the temperature conditions in the primary separator.

[0080] In the above experimental method, preferably, in step (1), the temperature inside the primary separator is above the highest flash point temperature of one or more combinations of C1-C5 light alkanes, alcohols below C5, aldehydes below C5, ethers below C5, and ketones below C5. More preferably, the temperature inside the primary separator is 20-30°C.

[0081] In the above experimental method, preferably, in step (3), the pressure P2 in the secondary separator is atmospheric pressure or 0.5 to 1 MPa below the saturated vapor pressure of the solvent under the temperature conditions in the secondary separator.

[0082] In the above experimental method, preferably, in step (3), the temperature in the secondary separator is above the highest flash point temperature of one or more of the following: light alkanes of C6-C10, light aromatics of C6-C10, alcohols of C6-C10, aldehydes of C6-C10, ethers of C6-C10, and ketones of C6-C10.

[0083] According to a specific embodiment of the present invention, the pressure inside the first and second separators can be detected in real time by using the first and second pressure sensors installed at the top of the first and second separators, and the pressure inside the first and second separators can be controlled and adjusted in real time by using the valves installed on the pipelines connected to the gas outlets at the top of the first and second separators to achieve dynamic pressure balance.

[0084] In the above experimental method, preferably, in step (2), the gaseous solvent discharged from the top of the primary separator is metered to a flow rate of Q1 by the first gas mass flow controller and then enters the primary gas container.

[0085] In the above experimental method, preferably, in step (3), the gaseous solvent discharged from the top of the secondary separator is metered to a flow rate of Q2 by the second gas mass flow controller and then enters the secondary gas container.

[0086] In the above experimental method, preferably, in step (4), the pressure of the solvent chamber of the piston gas collector is adjusted in real time by the pressure regulating valve at the top of the piston gas collector, and the gaseous solvent discharged from the primary gas container and the secondary gas container enters the solvent chamber of the piston gas collector.

[0087] In the above experimental method, preferably, in step (5), the gaseous solvent discharged from the piston gas collector is pressurized and liquefied by a compressor, and then the liquid solvent is re-injected into the reservoir after the flow rate is measured to Q3 by a third gas mass flow controller.

[0088] In the above method, preferably, in step (5), the pressure of the solvent after the gaseous solvent discharged from the piston gas collector is pressurized and liquefied by the compressor is 0.5-1.0 MPa above the saturated vapor pressure of the solvent.

[0089] In the above experimental method, preferably, the pressure in the solvent chamber of the piston-type gas collector is less than or equal to the pressure in the primary gas container and the secondary gas container.

[0090] In the above experimental method, preferably, the pressure in the solvent chamber of the piston gas collector is less than or equal to the outlet pressure of the compressor.

[0091] According to a specific embodiment of the present invention, preferably, the above experimental method further includes step (6): calculating the real-time solvent reinjection rate by real-time monitoring Q1, Q2 and Q3, where solvent reinjection rate = (Q1+Q2)×100% / Q3.

[0092] According to a specific embodiment of the present invention, preferably, the above experimental method further includes step (7): weighing the weight of the mixture containing crude oil in the crude oil collection container in real time using a weighing device.

[0093] This invention provides a system and method for closed-loop solvent separation and reinjection, as well as an experimental system and method for closed-loop solvent separation and reinjection. This invention enables accurate simulation of solvent circulation sampling or solvent circulation sampling, and allows for precise measurement of the closed-loop solvent separation and reinjection rate.

[0094] The technical solution of the present invention has at least the following beneficial effects:

[0095] (1) This invention employs a two-stage separator to achieve online separation of mixed solvents with different flash points. The first-stage separator is used for pressurized separation of low-flash-point solvents, while the second-stage separator is used for separating high-flash-point solvents. This two-stage separation significantly improves the solvent separation efficiency from the produced crude oil. Furthermore, the second-stage separator of this invention has a heating function, which further enhances the speed and efficiency of removing high-flash-point solvents from the crude oil. The overall solvent separation efficiency of this invention can reach over 98%.

[0096] (2) It can detect the gas-liquid interface inside the first-stage separator and the second-stage separator in a timely manner, preventing gas from escaping from the liquid outlet at the bottom of the separator, thereby greatly improving the efficiency of gas-liquid separation.

[0097] (3) The present invention uses a piston-type gas collector to measure the amount of solvent produced in a timely manner and compare it with the amount of solvent injected to obtain the timely solvent reinjection rate.

[0098] The system and method of the present invention can realize the closed-loop separation and reinjection of solvents in the solvent injection development process of heavy oil and extra-heavy oil reservoirs, and can realize circulating solvent injection, thereby improving the oil recovery rate. Attached Figure Description

[0099] Figure 1 This is a schematic diagram of a solvent closed-loop circulation separation and reinjection system provided in a specific embodiment of the present invention.

[0100] Figure 2 This is a schematic diagram showing the communication connection between the first gas / liquid interface probe and the first pressure sensor of the first-stage separator in a specific embodiment of the present invention and the data acquisition and processing device.

[0101] Figure 3 This is a schematic diagram of the experimental system for closed-loop solvent separation and reinjection provided in a specific embodiment of the present invention.

[0102] Explanation of icon numbers:

[0103] 1-Oil reservoir; 2-First-stage separator; 3-Second-stage separator; 4-First-stage gas container; 5-Second-stage gas container; 6-Piston gas collector; 7-Data acquisition and processing device; 8-Crude oil collection container; 9-Weighing device; 10-First gas mass flow controller; 11-Second gas mass flow controller; 12-Third gas mass flow controller; 13-Compressor;

[0104] 101 - Experimental Model;

[0105] 201 - First injection mechanism; 202 - First gas / liquid interface probe; 203 - First pressure sensor;

[0106] 301 - Second injection mechanism; 302 - Second gas / liquid interface probe; 303 - Second pressure sensor; 304 - Heating jacket;

[0107] 601 - Discharge line; 602 - Piston; 603 - Third pressure sensor; 604 - Pressure regulating chamber; 605 - Solvent chamber; 606 - Pressure regulating valve. Detailed Implementation

[0108] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0109] Example 1

[0110] This embodiment provides a system for closed-loop solvent separation and reinjection, the structure of which is as follows: Figure 1 As shown.

[0111] The system includes: a primary separator 2, a secondary separator 3, a primary gas container 4, a secondary gas container 5, a piston-type gas collector 6, a data acquisition and processing device 7, a crude oil collection container 8, a weighing device 9, a first gas mass flow controller 10, a second gas mass flow controller 11, a third gas mass flow controller 12, and a compressor 13.

[0112] Other, Figure 1 The image also shows reservoir 1.

[0113] The primary separator 2 is provided with at least an injection port, a liquid outlet, a gas outlet, a first injection mechanism 201, a first gas / liquid interface probe 202, and a first pressure sensor 203. The injection port and the liquid outlet are located at the bottom of the primary separator 2; the gas outlet is located at the top of the primary separator 2; the first injection mechanism 201 is located inside the cavity of the primary separator 2 and is connected to the injection port; the first gas / liquid interface probe 202 is located inside the cavity of the primary separator 2; and the first pressure sensor 203 is located on a pipeline connected to the gas outlet and is used to detect the pressure inside the primary separator 2.

[0114] The primary separator 2 is used to achieve pressurized primary separation of solvent in a mixture containing crude oil and solvent.

[0115] Valves are installed on the pipelines connecting the liquid outlet and gas outlet of the first-stage separator 2. A valve is also installed on the pipeline connecting the inlet of the first-stage separator 2.

[0116] One end of the first injection mechanism 201 is connected to the injection port of the primary separator 2, and the other end has an injection port. The first injection mechanism 201 is used to inject the mixture containing crude oil and solvent into the primary separator 2 from bottom to top. Furthermore, the first injection mechanism 201 is arranged perpendicular to the bottom surface of the primary separator 2.

[0117] The length of the first injection mechanism 201 is half the height of the inner cavity of the first-stage separator 2.

[0118] The first gas / liquid interface probe 202 is a resistance probe.

[0119] The first gas / liquid interface probe 202 is arranged in parallel with the first injection mechanism 201.

[0120] The height of the first gas / liquid interface probe 202 is 1 / 2 to 3 / 4 of the height of the inner cavity of the first-stage separator 2.

[0121] The inlet of primary separator 2 is used to allow the mixture of crude oil and solvent produced by reservoir 1 to enter primary separator 2. The liquid outlet of primary separator 2 is connected to the inlet of secondary separator 3 via a pipeline.

[0122] The gas outlet of the first-stage separator 2 is connected to the inlet of the first-stage gas container 4 via a pipeline.

[0123] The secondary separator 3 is provided with at least an injection port, a liquid outlet, a gas outlet, a second injection mechanism 301, a second gas / liquid interface probe 302, and a second pressure sensor 303; the injection port and the liquid outlet are located at the bottom of the secondary separator 3; the gas outlet is located at the top of the secondary separator 3; the second injection mechanism 301 is located inside the cavity of the secondary separator 3 and communicates with the injection port; the second gas / liquid interface probe 302 is located inside the cavity of the secondary separator 3; and the second pressure sensor 303 is located on a pipeline communicating with the gas outlet and is used to detect the pressure inside the secondary separator 3.

[0124] A heating jacket 304 is provided on the outside of the secondary separator 3.

[0125] The secondary separator 3 is used to achieve pressurized or unpressurized secondary separation of the solvent in the mixed system containing crude oil and solvent obtained after the primary separator 2 separates a portion of the solvent.

[0126] Valves are installed on the pipelines connecting the liquid outlet and gas outlet of the secondary separator 3.

[0127] One end of the second injection mechanism 301 is connected to the injection port of the secondary separator 3, and the other end has an injection port. The second injection mechanism 301 is used to inject the mixture containing crude oil and solvent obtained after a portion of the solvent is separated in the primary separator 2 into the secondary separator 3 from bottom to top. Furthermore, the second injection mechanism 301 is arranged perpendicular to the bottom surface of the secondary separator 3.

[0128] The length of the second injection mechanism 301 is half the height of the inner cavity of the secondary separator 3.

[0129] The second gas / liquid interface probe 302 is a resistance probe.

[0130] The second gas / liquid interface probe 302 is arranged in parallel with the second injection mechanism 301.

[0131] The height of the second gas / liquid interface probe 302 is 1 / 2 to 3 / 4 of the height of the inner cavity of the secondary separator 3.

[0132] The gas outlet of the secondary separator 3 is connected to the inlet of the secondary gas container 5 via a pipeline.

[0133] In this embodiment, gas / liquid interface probes are set in the primary separator 2 and the secondary separator 3 respectively to detect the gas-liquid interface. By utilizing the difference in resistivity between the gas and the liquid, and feeding this difference back to the control software in the data acquisition and processing device 7, the gas-liquid interface can be monitored and determined in a timely manner.

[0134] In this embodiment, the first pressure sensor 203 and the second pressure sensor 303 installed at the top of the primary separator 2 and the secondary separator 3 can detect the pressure inside the primary separator 2 and the secondary separator 3 in real time. The valve installed on the pipeline connected to the gas outlet at the top of the primary separator 2 and the secondary separator 3 can control and adjust the pressure inside the primary separator 2 and the secondary separator 3 in real time to achieve dynamic pressure balance.

[0135] The primary gas container 4 is equipped with at least an inlet and an outlet. The primary gas container 4 is used to collect the gaseous solvent separated by the primary separator 2.

[0136] The secondary gas container 5 is equipped with at least an inlet and an outlet. The secondary gas container 5 is used to collect the gaseous solvent separated by the secondary separator 3.

[0137] The piston-type gas collector 6 is equipped with at least an injection port, an outlet, a discharge line 601, a piston 602, and a third pressure sensor 603. The injection port is located at the bottom of the piston-type gas collector 6; the outlet is located at the top of the piston-type gas collector 6; the discharge line 601 is located inside the cavity of the piston-type gas collector 6 and communicates with the outlet; the piston 602 is located inside the cavity of the piston-type gas collector 6; and the third pressure sensor 603 is located on the line communicating with the outlet and is used to detect the pressure inside the piston-type gas collector 6. The piston-type gas collector 6 is used to collect gaseous solvent from the primary gas container 4 and the secondary gas container 5, and after remixing, it is used for reinjection.

[0138] The piston-type gas collector 6 has two inlets, which are connected to the outlet of the primary gas container 4 and the outlet of the secondary gas container 5 via pipelines, respectively. Valves are installed on the pipelines connecting the two inlets of the piston-type gas collector 6.

[0139] When gaseous solvent from the primary gas container 4 and the secondary gas container 5 is injected into the piston-type gas collector 6, it pushes the piston 602 located at the bottom of the inner cavity of the piston-type gas collector 6 to move upward. The piston 602 divides the cavity of the piston-type gas collector 6 into a pressure regulating chamber 604 above the piston 602 and a solvent chamber 605 below the piston 602. Those skilled in the art will understand that one end of the discharge line 601 in the piston-type gas collector 6 should extend into the solvent chamber 605, and the other end of the discharge line 601 should be connected to the discharge port of the piston-type gas collector 6.

[0140] The piston-type gas collector 6 is also equipped with a pressure regulating valve 606, which is located at the top of the piston-type gas collector 6. The pressure regulating valve 606 is used to regulate the pressure in the solvent chamber 605 through the pressure regulating chamber 604. The pressure in the solvent chamber 605 can be adjusted in a timely manner through the pressure regulating valve 606 and the pressure regulating chamber 604 to achieve dynamic balance control and mixing of gaseous solvent before reinjection.

[0141] The data acquisition and processing device 7 is communicatively connected to the first gas / liquid interface probe 202, the second gas / liquid interface probe 302, the first pressure sensor 203, the second pressure sensor 303, and the third pressure sensor 603, and is used to collect, monitor, and process the data detected by the gas / liquid interface probes and pressure sensors. In this embodiment, the data acquisition and processing device 7 may include devices such as a data acquisition unit and a computer. The communication connection may include an electrical connection. A schematic diagram showing the communicative connection between the first gas / liquid interface probe 202 and the first pressure sensor 203 of the first-stage separator 2 and the data acquisition and processing device 7 is shown below. Figure 2 As shown.

[0142] The crude oil collection container 8 is connected to the liquid outlet of the secondary separator 3 via a pipeline. The crude oil collection container 8 is used to collect the mixed system containing crude oil obtained after sequential separation by the primary separator 2 and the secondary separator 3. In this embodiment, the crude oil collection container 8 can be a conventional collection container in the art, including but not limited to beakers.

[0143] The weighing device 9 is used to weigh the mixture containing crude oil in the crude oil collection container 8. In this embodiment, the weighing device 9 can be a conventional device in the art, including but not limited to an online weighing platform.

[0144] A first gas mass flow controller 10 is installed on the pipeline connecting the first-stage separator 2 and the first-stage gas container 4 to measure and control the mass and volume flow rate of the gaseous solvent separated by the first-stage separator 2 in real time.

[0145] A second gas mass flow controller 11 is installed on the pipeline connecting the secondary separator 3 and the secondary gas container 5 to measure and control the mass and volume flow rate of the gaseous solvent separated by the secondary separator 3 in real time.

[0146] A compressor 13 is installed on the pipeline connected to the outlet of the piston-type gas collector 6 to pressurize the solvent to the pre-injection pressure in preparation for injection into the oil reservoir 1. Furthermore, a valve is installed on the pipeline connecting the outlet of the piston-type gas collector 6 to the compressor 13.

[0147] A third gas mass flow controller 12 is installed on the pipeline connected to the outlet of the piston-type gas collector 6 to measure and control the mass and volume flow rate of the reinjected solvent in real time. Furthermore, the third gas mass flow controller 12 is located downstream of the compressor 13.

[0148] The outlet of the piston-type gas collector 6 is connected to the solvent injection port of the reservoir 1 through pipelines, compressor 13, third gas mass flow controller 12 and valves to realize the closed-loop circulation separation and reinjection of solvent.

[0149] Example 2

[0150] This embodiment provides a method for solvent closed-loop separation and reinjection. The method uses the solvent closed-loop separation and reinjection system provided in Example 1, and includes the following steps:

[0151] (1) The mixture of crude oil and solvent produced by reservoir 1 is introduced into primary separator 2. The gas / liquid interface is monitored in real time using the first gas / liquid interface probe 202 to control the height of the gas / liquid interface to be less than 1 / 5 of the height of the inner cavity of primary separator 2, and to make the pressure in primary separator 2 reach P1. P1 is 0.5 to 1 MPa below the saturated vapor pressure of the solvent under the temperature conditions in primary separator 2. The temperature in primary separator 2 is above the highest flash point temperature of one or more of the following: light alkanes of C1-C5, alcohols below C5, aldehydes below C5, ethers below C5 and ketones below C5, preferably 20-30°C.

[0152] (2) After the pressure in the first-stage separator 2 reaches P1, open the valves at the top and bottom of the first-stage separator 2 to start gas-liquid separation. The gaseous solvent discharged from the top of the first-stage separator 2 enters the first-stage gas container 4 after the flow rate is measured to Q1 by the first gas mass flow controller 10. The mixed system containing crude oil and solvent discharged from the bottom of the first-stage separator 2 enters the second-stage separator 3.

[0153] (3) The gas-liquid interface in the secondary separator 3 is monitored in real time using the second gas / liquid interface probe 302. When the gas-liquid interface in the secondary separator 3 reaches more than 1 / 3 of the height of the inner cavity of the secondary separator 3, the valves at the top and bottom of the secondary separator 3 are opened to start the secondary gas-liquid separation. The pressure in the secondary separator 3 is P2, which is atmospheric pressure or 0.5 to 1 MPa below the saturated vapor pressure of the solvent under the temperature conditions in the secondary separator 3. The temperature in the secondary separator is above the highest flash point temperature of one or more of the following: light alkanes, light aromatics, alcohols, aldehydes, ethers, and ketones. The gaseous solvent discharged from the top of the secondary separator 3 is metered at a flow rate of Q2 by the second gas mass flow controller 11 and enters the secondary gas container 5. The mixed system containing crude oil discharged from the bottom of the secondary separator 3 enters the crude oil collection container 8.

[0154] (4) The pressure of the solvent chamber 605 of the piston gas collector 6 is adjusted in real time by the pressure regulating valve 606 at the top of the piston gas collector 6 so that the gaseous solvent discharged from the primary gas container 4 and the secondary gas container 5 can enter the solvent chamber 605 of the piston gas collector 6.

[0155] (5) The gaseous solvent discharged from the piston gas collector 6 is pressurized and liquefied by the compressor 13. After passing through the compressor 13, the pressure of the solvent is 0.5-1.0 MPa above the saturated vapor pressure of the solvent. Then, the flow rate of the liquid solvent is measured to Q3 by the third gas mass flow controller 12, and the liquid solvent is reinjected into the reservoir 1.

[0156] (6) Calculate the real-time solvent reinjection rate by monitoring Q1, Q2 and Q3 in real time. Solvent reinjection rate = (Q1+Q2)×100% / Q3.

[0157] The solvent includes one or a combination of several of the following: light alkanes of C1-C10, light aromatics of C6-C10, alcohols below C10, aldehydes below C10, ethers below C10, and ketones below C10.

[0158] In this embodiment, the first pressure sensor 203 and the second pressure sensor 303 installed on the top of the primary separator 2 and the secondary separator 3 can detect the pressure in the primary separator 2 and the secondary separator 3 in real time. The valve installed on the pipeline connected to the gas outlet at the top of the primary separator 2 and the secondary separator 3 can control and adjust the pressure in the primary separator 2 and the secondary separator 3 in real time to achieve dynamic pressure balance.

[0159] In this embodiment, the pressure in the solvent chamber 605 of the piston-type gas collector 6 is P5, the pressure in the primary gas container 4 is P3, and the pressure in the secondary gas container 5 is P4. To ensure that the gaseous containers in the primary gas container 4 and the secondary gas container 5 can enter the piston-type gas collector 6, P5 needs to be controlled to be less than or equal to P3 and P4. Simultaneously, the outlet pressure of the compressor 13 is P7. To ensure that the gaseous solvent in the piston-type gas collector 6 can enter the compressor 13, the outlet pressure P7 of the compressor 13 needs to be controlled to be greater than or equal to the pressure P5 in the solvent chamber 605 of the piston-type gas collector 6 (this pressure is also the inlet pressure of the compressor 13). The pressure P5 in the solvent chamber 605 of the piston-type gas collector 6 needs to be adjusted to simultaneously satisfy the above conditions, that is, P5 needs to be less than or equal to P3, P4, and P7. The pressure P5 in the solvent chamber 605 of the piston-type gas collector 6 is controlled by the pressure regulating valve 606 at the top of the piston-type gas collector 6. The pressure regulating valve 606 adjusts the pressure P6 in the upper pressure regulating chamber 604 in a timely manner by releasing gas, so that P5 simultaneously meets the above conditions. By adjusting the pressure P5 in the solvent chamber 605 of the piston-type gas collector 6 in real time, dynamic balance control and mixing of gaseous solvent before reinjection can be achieved.

[0160] In this embodiment, the above method further includes step (7): weighing and recording the weight of the mixture containing crude oil in the crude oil collection container 8 in real time using the weighing device 9.

[0161] This embodiment realizes the closed-loop circulation, separation, and injection of solvent.

[0162] Example 3

[0163] This embodiment provides an experimental system for closed-loop solvent separation and reinjection, the structure of which is as follows: Figure 3 As shown.

[0164] The experimental system includes the solvent closed-loop circulation separation and reinjection system provided in Example 1, and an experimental model 101. The experimental model 101 is provided with at least an injection port and an outlet port. The injection port is located at the top of the experimental model 101, and the outlet port is located at the bottom of the experimental model 101. The outlet port of the experimental model 101 is connected to the injection port of the primary separator 2 through a pipeline, and a valve is provided on the pipeline. The injection port of the experimental model 101 is connected to the outlet port of the piston gas collector 6 through a pipeline, and a compressor 13, a third gas mass flow controller 12, and a valve are provided on the pipeline.

[0165] In the experimental model 101, valves installed on the pipelines connecting the injection port and the discharge port are used to control the injection of solvent and the discharge of the mixture containing crude oil and solvent, respectively.

[0166] Experimental model 101 can employ a high-temperature, high-pressure gas-liquid separator. This high-temperature, high-pressure gas-liquid separator can be a conventional device in the field, and the present invention does not impose any special limitations on its specific structure.

[0167] The height of the first gas / liquid interface probe 202 is half the height of the inner cavity of the first-stage separator 2, and the height of the second gas / liquid interface probe 302 is half the height of the inner cavity of the second-stage separator 3.

[0168] This embodiment also provides an experimental method for solvent closed-loop separation and reinjection, which uses the experimental system for solvent closed-loop separation and reinjection of this embodiment.

[0169] The solvents used in the experimental method of this embodiment include C1 light alkanes and C8 light aromatics.

[0170] The experimental method includes the following steps:

[0171] (1) Set the outlet back pressure of the experimental model 101. Under the back pressure control, the mixture system containing crude oil and solvent in the experimental model 101 enters the first-stage separator 2. The gas / liquid interface is monitored in real time using the first gas / liquid interface probe 202 to control the height of the gas / liquid interface to be less than 1 / 5 of the inner cavity height of the first-stage separator 2, and to make the pressure in the first-stage separator 2 reach P1. P1 is 0.5 MPa below the saturated vapor pressure of the solvent under the temperature conditions in the first-stage separator 2. The temperature in the first-stage separator 2 is 20-30℃.

[0172] (2) After the pressure in the first-stage separator 2 reaches P1, open the valves at the top and bottom of the first-stage separator 2 to start gas-liquid separation. The gaseous solvent discharged from the top of the first-stage separator 2 enters the first-stage gas container 4 after the flow rate is measured to Q1 by the first gas mass flow controller 10. The mixed system containing crude oil and solvent discharged from the bottom of the first-stage separator 2 enters the second-stage separator 3.

[0173] (3) The gas-liquid interface in the secondary separator 3 is monitored in real time using the second gas / liquid interface probe 302. When the gas-liquid interface in the secondary separator 3 reaches more than 1 / 3 of the height of the inner cavity of the secondary separator 3, the valves at the top and bottom of the secondary separator 3 are opened to start the secondary gas-liquid separation. The pressure in the secondary separator 3 is P2, which is 0.5 MPa below the saturated vapor pressure of the solvent under the temperature conditions in the secondary separator 3. The temperature in the secondary separator 3 is 124℃. The gaseous solvent discharged from the top of the secondary separator 3 is metered at a flow rate of Q2 by the second gas mass flow controller 11 and then enters the secondary gas container 5. The mixed system containing crude oil discharged from the bottom of the secondary separator 3 enters the crude oil collection container 8.

[0174] (4) The pressure of the solvent chamber 605 of the piston gas collector 6 is adjusted in real time by the pressure regulating valve 606 at the top of the piston gas collector 6 so that the gaseous solvent discharged from the primary gas container 4 and the secondary gas container 5 can enter the solvent chamber 605 of the piston gas collector 6.

[0175] (5) The gaseous solvent discharged from the piston gas collector 6 is pressurized and liquefied by the compressor 13. After passing through the compressor 13, the pressure of the solvent is 0.5 MPa above the saturated vapor pressure of the solvent. Then, the flow rate of the liquid solvent is measured to be Q3 by the third gas mass flow controller 12, and the liquid solvent is re-injected into the experimental model 101.

[0176] (6) Calculate the real-time solvent reinjection rate by monitoring Q1, Q2 and Q3 in real time. Solvent reinjection rate = (Q1 + Q2) × 100% / Q3;

[0177] (7) Weigh and record the weight of the mixture containing crude oil in the crude oil collection container 8 in real time using the weighing device 9.

[0178] This embodiment achieves closed-loop circulation, separation, and injection / production of the solvent, with an overall separation efficiency of 99%. The cumulative injection volume Q3 is 20L, the cumulative production volume Q1 is 16.6L, Q2 is 2.1L, and the cumulative solvent recycling rate is 93.5%.

[0179] Example 4

[0180] This embodiment provides an experimental system for closed-loop solvent separation and reinjection. The structure of this experimental system is basically the same as that of Embodiment 3, except that the height of the first gas / liquid interface probe 202 is 3 / 4 of the height of the inner cavity of the first-stage separator 2, and the height of the second gas / liquid interface probe 302 is 3 / 4 of the height of the inner cavity of the second-stage separator 3.

[0181] This embodiment also provides an experimental method for closed-loop solvent separation and reinjection, which is basically the same as that in Embodiment 3, except that: P1 is 1 MPa below the saturated vapor pressure of the solvent under the temperature conditions in the first-stage separator 2, and the temperature in the first-stage separator 2 is 20-30°C; and P2 is 1 MPa below the saturated vapor pressure of the solvent under the temperature conditions in the second-stage separator 3, and the temperature in the second-stage separator 3 is 100°C; and the pressure of the solvent after passing through the compressor 13 is 1 MPa above the saturated vapor pressure of the solvent.

[0182] The solvent used in the experimental method of this embodiment consists of ethane, dimethyl ether, n-heptane, and n-octane.

[0183] This embodiment achieves closed-loop circulation, separation, and injection / production of the solvent, with an overall separation efficiency of 99%. The cumulative injection volume is Q3 = 20L, the cumulative production volume is Q1 = 17.6L, Q2 = 1.0L, and the cumulative solvent recycling rate is 18.6 / 20 = 93%.

Claims

1. A closed-loop solvent circulation separation and reinjection system, comprising: Primary separator, secondary separator, primary gas container, secondary gas container, crude oil collection container, piston gas collector; The primary separator includes at least one injection port, one liquid outlet, one gas outlet, a first injection mechanism, a first gas / liquid interface probe, and a first pressure sensor. The injection port and the liquid outlet are located at the bottom of the primary separator; the gas outlet is located at the top of the primary separator; the first injection mechanism is located inside the cavity of the primary separator and communicates with the injection port; the first gas / liquid interface probe is located inside the cavity of the primary separator; and the first pressure sensor is located on a pipeline communicating with the gas outlet for detecting the pressure inside the primary separator. The secondary separator is provided with at least two injection ports, two liquid outlets, two gas outlets, a second injection mechanism, a second gas / liquid interface probe, and a second pressure sensor; the second injection port and the second liquid outlet are located at the bottom of the secondary separator; the second gas outlet is located at the top of the secondary separator; the second injection mechanism is located inside the cavity of the secondary separator and communicates with the second injection port; the second gas / liquid interface probe is located inside the cavity of the secondary separator; the second pressure sensor is located on a pipeline communicating with the second gas outlet and is used to detect the pressure inside the secondary separator. The primary gas container is provided with at least three injection ports and three discharge ports; The secondary gas container is provided with at least four injection ports and four discharge ports; The piston-type gas collector is provided with at least five injection ports, five discharge ports, a discharge pipeline, a piston, and a third pressure sensor; the five injection ports are located at the bottom of the piston-type gas collector; the five discharge ports are located at the top of the piston-type gas collector; the discharge pipeline is located inside the cavity of the piston-type gas collector and communicates with the five discharge ports; the piston is located inside the cavity of the piston-type gas collector; the third pressure sensor is located on the pipeline communicating with the five discharge ports and is used to detect the pressure inside the piston-type gas collector. The injection port of the primary separator is used to allow a mixture containing crude oil and solvent to enter the primary separator; The liquid outlet of the primary separator is connected to the inlet of the secondary separator via a pipeline. The gas outlet of the first-stage separator is connected to the inlet of the first-stage gas container via a pipeline. The second gas outlet of the secondary separator is connected to the fourth inlet of the secondary gas container via a pipeline; The outlet three of the primary gas container and the outlet four of the secondary gas container are connected to the inlet five of the piston-type gas collector via pipelines. The crude oil collection container is connected to the liquid outlet of the secondary separator via a pipeline.

2. The solvent closed-loop circulation separation and reinjection system according to claim 1, wherein, The system further includes a data acquisition and processing device, which is communicatively connected to a first gas / liquid interface probe, a second gas / liquid interface probe, a first pressure sensor, a second pressure sensor, and a third pressure sensor, for collecting, monitoring, and processing data detected by the gas / liquid interface probe and the pressure sensor.

3. The solvent closed-loop circulation separation and reinjection system according to claim 1, wherein, One end of the first injection mechanism is connected to the injection port of the first-stage separator, and the other end has an injection port. The first injection mechanism is used to inject the mixture containing crude oil and solvent into the first-stage separator from bottom to top.

4. The solvent closed-loop circulation separation and reinjection system according to claim 1, wherein, The first injection mechanism is positioned perpendicular to the bottom surface of the primary separator.

5. The solvent closed-loop circulation separation and reinjection system according to claim 1, wherein, The length of the first injection mechanism is 1 / 2 to 2 / 3 of the height of the inner cavity of the first-stage separator.

6. The solvent closed-loop circulation separation and reinjection system according to claim 1, wherein, The first gas / liquid interface probe is a resistance probe.

7. The solvent closed-loop circulation separation and reinjection system according to claim 1, wherein, The first gas / liquid interface probe is arranged in parallel with the first injection mechanism.

8. The solvent closed-loop circulation separation and reinjection system according to claim 1, wherein, The height of the first gas / liquid interface probe is 1 / 2 to 3 / 4 of the height of the inner cavity of the first-stage separator.

9. The solvent closed-loop circulation separation and reinjection system according to claim 1, wherein, One end of the second injection mechanism is connected to the injection port of the secondary separator, and the other end has an injection port. The second injection mechanism is used to inject the mixture containing crude oil and solvent obtained after the primary separator separates a portion of the solvent into the secondary separator from bottom to top.

10. The solvent closed-loop circulation separation and reinjection system according to claim 1, wherein, The second injection mechanism is positioned perpendicular to the bottom surface of the secondary separator.

11. The solvent closed-loop circulation separation and reinjection system according to claim 1, wherein, The length of the second injection mechanism is 1 / 2 to 2 / 3 of the height of the inner cavity of the secondary separator.

12. The solvent closed-loop circulation separation and reinjection system according to claim 1, wherein, The second gas / liquid interface probe is a resistance probe.

13. The solvent closed-loop circulation separation and reinjection system according to claim 1, wherein, The second gas / liquid interface probe is arranged in parallel with the second injection mechanism.

14. The solvent closed-loop circulation separation and reinjection system according to claim 1, wherein, The height of the second gas / liquid interface probe is 1 / 2 to 3 / 4 of the height of the inner cavity of the secondary separator.

15. The solvent closed-loop circulation separation and reinjection system according to claim 1, wherein, The secondary separator is equipped with a heating jacket on its exterior.

16. The solvent closed-loop circulation separation and reinjection system according to claim 1, wherein, A first gas mass flow controller is installed on the pipeline connecting the first-stage separator and the first-stage gas container, which is used to measure at least the flow rate of the gaseous solvent separated by the first-stage separator.

17. The solvent closed-loop circulation separation and reinjection system according to claim 1, wherein, A second gas mass flow controller is installed on the pipeline connecting the secondary separator and the secondary gas container, which is used at least to measure the flow rate of the gaseous solvent separated by the secondary separator.

18. The solvent closed-loop circulation separation and reinjection system according to claim 1, wherein, When gaseous solvent from the primary gas container and the secondary gas container is injected into the piston-type gas collector, it pushes the piston located at the bottom of the inner cavity of the piston-type gas collector to move upward. The piston divides the cavity of the piston-type gas collector into a pressure regulating chamber at the top of the piston and a solvent chamber at the bottom of the piston.

19. The solvent closed-loop circulation separation and reinjection system according to claim 18, wherein, The piston-type gas collector is also equipped with a pressure regulating valve, which is located at the top of the piston-type gas collector and is used to regulate the pressure in the solvent chamber through the pressure regulating chamber.

20. The solvent closed-loop circulation separation and reinjection system according to claim 1, wherein, A compressor is installed on the pipeline connected to the outlet of the piston gas collector to pressurize the solvent to the injection pressure.

21. The solvent closed-loop circulation separation and reinjection system according to claim 1, wherein, A third gas mass flow controller is installed on the pipeline connected to the outlet of the piston-type gas collector, which is used at least to measure the flow rate of the reinjected solvent.

22. A method for solvent closed-loop separation and reinjection, the method employing the solvent closed-loop separation and reinjection system according to any one of claims 1-21, the method comprising the following steps: (1) The mixture system containing crude oil and solvent produced by the reservoir is brought into the first-stage separator, the gas-liquid interface is monitored in real time using the first gas / liquid interface probe, and the pressure in the first-stage separator is made to reach P1. (2) After the pressure in the first-stage separator reaches P1, the gaseous solvent is discharged from the top of the first-stage separator and enters the first-stage gas container, and the mixture containing crude oil and solvent is discharged from the bottom of the first-stage separator and enters the second-stage separator. (3) The gas-liquid interface in the secondary separator is monitored in real time using the second gas / liquid interface probe. When the gas-liquid interface in the secondary separator reaches more than 1 / 3 of the height of the secondary separator cavity, the gaseous solvent is discharged from the top of the secondary separator and enters the secondary gas container, and the mixed system containing crude oil is discharged from the bottom of the secondary separator and enters the crude oil collection container. The pressure in the secondary separator is P2. (4) Adjust the pressure inside the piston gas collector in real time so that the gaseous solvent discharged from the primary gas container and the secondary gas container can enter the piston gas collector. (5) After pressurizing and liquefying the gaseous solvent discharged from the piston gas collector, it is reinjected into the reservoir.

23. The method for closed-loop solvent separation and reinjection according to claim 22, wherein, The solvent includes one or a combination of several of the following: light alkanes of C1-C10, light aromatics of C6-C10, alcohols below C10, aldehydes below C10, ethers below C10, and ketones below C10.

24. The method for closed-loop solvent separation and reinjection according to claim 22, wherein, In step (1), the pressure P1 inside the primary separator is 0.5~1 MPa below the saturated vapor pressure of the solvent under the temperature conditions inside the primary separator.

25. The method for closed-loop solvent separation and reinjection according to claim 23, wherein, In step (1), the temperature inside the primary separator is above the highest flash point temperature of one or more of the following: light alkanes of C1-C5, alcohols below C5, aldehydes below C5, ethers below C5, and ketones below C5.

26. The method for closed-loop solvent separation and reinjection according to claim 25, wherein, In step (1), the temperature inside the primary separator is 20-30℃.

27. The method for closed-loop solvent separation and reinjection according to claim 22, wherein, In step (3), the pressure P2 inside the secondary separator is atmospheric pressure or 0.5~1 MPa below the saturated vapor pressure of the solvent under the temperature conditions inside the secondary separator.

28. The method for closed-loop solvent separation and reinjection according to claim 23, wherein, In step (1) and in step (3), the temperature inside the secondary separator is above the highest flash point temperature of one or more of the following: light alkanes of C6-C10, light aromatics of C6-C10, alcohols of C6-C10, aldehydes of C6-C10, ethers of C6-C10, and ketones of C6-C10.

29. The method for closed-loop solvent separation and reinjection according to claim 22, wherein, In step (2), the gaseous solvent discharged from the top of the first-stage separator is metered to a flow rate of Q1 by the first gas mass flow controller and then enters the first-stage gas container; In step (3), the gaseous solvent discharged from the top of the secondary separator is metered to a flow rate of Q2 by the second gas mass flow controller and then enters the secondary gas container; In step (5), the gaseous solvent discharged from the piston gas collector is pressurized and liquefied by the compressor, and then the liquid solvent is re-injected into the reservoir after the flow rate is measured to Q3 by the third gas mass flow controller.

30. The method for closed-loop solvent separation and reinjection according to claim 22, wherein, In step (4), the pressure of the solvent chamber of the piston gas collector is adjusted in real time by the pressure regulating valve at the top of the piston gas collector, and the gaseous solvent discharged from the primary gas container and the secondary gas container enters the solvent chamber of the piston gas collector.

31. The method for closed-loop solvent separation and reinjection according to claim 29, wherein, The above method further includes step (6): calculating the real-time solvent reinjection rate by real-time monitoring Q1, Q2 and Q3, where solvent reinjection rate = (Q1 + Q2) × 100% / Q3.

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