System and method for closed circulation separation and reinjection of solvent

Abstract

The invention provides a solvent closed circulation separation and reinjection system and a solvent closed circulation separation and reinjection method. The system comprises a first-stage separator, a second-stage separator, a first-stage gas container, a second-stage gas container, a crude oil collecting container and a piston type gas collector. The method comprises the following steps: a mixed system containing crude oil and a solvent enters a primary separator for separation; discharging the gaseous solvent from the first-stage separator, feeding the gaseous solvent into a first-stage gas container, discharging a liquid mixed system from the first-stage separator, and feeding the liquid mixed system into a second-stage separator for separation; discharging the gaseous solvent from the second-stage separator and feeding the gaseous solvent into a second-stage gas container, discharging the liquid mixed system from the second-stage separator and feeding the liquid mixed system into a crude oil collecting container; the gaseous solvent discharged from the first-stage gas container and the second-stage gas container enters the piston type gas collector, is pressurized and liquefied, and then is injected into the oil reservoir again. According to the system and the method, solvent closed circulation separation and reinjection in the thick oil and super-thick oil recovery process are achieved, and the crude oil recovery rate is increased.

Description

Technical Field

[0001] The invention relates to a system and method for solvent closed cycle separation and reinjection, belonging to the field of petroleum exploitation. Background Art

[0002] Shallow super-heavy oil has high viscosity and poor fluidity in high-temperature areas. Simply relying on steam to reduce viscosity is not ideal. Under high temperature conditions of 200°C in the steam-affected area, the viscosity of super-heavy oil in some areas can reach 60-100mPa·s. Since the viscosity of crude oil directly affects the fluidity and production rate of oil, the production of super-heavy oil is relatively low when relying on conventional steam injection. For heavy oil and super-heavy oil reservoirs, it is urgent to explore new composite mining technologies that can further reduce the viscosity of crude oil on the basis of conventional steam injection.

[0003] Studies have shown that adding a small amount of light hydrocarbon solvent to steam can accelerate viscosity reduction and reduce the crude oil viscosity under steam chamber conditions to below 5mPa·s, which is a new way to significantly increase the production and recovery of heavy oil and extra-heavy oil. However, light hydrocarbon solvents are expensive and need to be recycled and reinjected to be economically effective. At present, there are few devices and methods for solvent reinjection. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a system and method for solvent closed cycle separation and reinjection. The system and method of the present invention can realize solvent closed cycle separation and reinjection in the process of solvent injection development of heavy oil and super heavy oil reservoirs, thereby improving crude oil recovery.

[0005] The present invention also aims to provide an experimental system and method for solvent closed cycle separation and reinjection. The experimental system of the present invention is a simulation experimental system for solvent injection exploitation of heavy oil and super heavy oil reservoirs, which can simulate solvent closed cycle separation and reinjection.

[0006] In order to achieve the above-mentioned object, the first aspect of the present invention provides a solvent closed cycle separation and reinjection system, which comprises: 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] Wherein, the primary separator is at least provided with an injection port, a liquid discharge port, a gas discharge port, a first injection mechanism, a first gas / liquid interface probe, and a first pressure sensor; the injection port and the liquid discharge port are arranged at the bottom of the primary separator; the gas discharge port is arranged at the top of the primary separator; the first injection mechanism is arranged in the cavity of the primary separator and is communicated with the injection port; the first gas / liquid interface probe is arranged in the cavity of the primary separator; the first pressure sensor is arranged on the pipeline communicated with the gas discharge port, and is used to detect the pressure inside the primary separator;

[0008] The secondary separator is at least provided with an injection port, a liquid discharge port, a gas discharge port, a second injection mechanism, a second gas / liquid interface probe, and a second pressure sensor; the injection port and the liquid discharge port are arranged at the bottom of the secondary separator; the gas discharge port is arranged at the top of the secondary separator; the second injection mechanism is arranged in the cavity of the secondary separator and is connected with the injection port; the second gas / liquid interface probe is arranged in the cavity of the secondary separator; the second pressure sensor is arranged on the pipeline connected with the gas discharge port, 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 at least provided with an injection port, a discharge port, a discharge pipeline, a piston, and a third pressure sensor; the injection port is provided at the bottom of the piston-type gas collector; the discharge port is provided at the top of the piston-type gas collector; the discharge pipeline is provided in the cavity of the piston-type gas collector and is communicated with the discharge port; the piston is provided in the cavity of the piston-type gas collector; the third pressure sensor is provided on the pipeline communicated with the discharge port, and is used to detect the pressure inside the piston-type gas collector;

[0012] The injection port of the primary separator is used to allow the mixed system containing crude oil and solvent to enter the primary separator;

[0013] The liquid outlet of the primary separator is connected to the injection port of the secondary separator through a pipeline;

[0014] The gas outlet of the primary separator is connected to the injection port of the primary gas container through a pipeline;

[0015] The gas outlet of the secondary separator is connected to the injection port of the secondary gas container through a pipeline;

[0016] The discharge port of the primary gas container and the discharge port of the secondary gas container are connected to the injection port of the piston type gas collector through pipelines;

[0017] The crude oil collection container is connected to the liquid discharge port of the secondary separator through a pipeline.

[0018] In the above-mentioned system, the primary separator is used to realize the primary separation of the solvent in the mixed system containing crude oil and solvent under pressure. The secondary separator is used to realize the secondary separation of the solvent in the mixed system containing crude oil and solvent under pressure or without pressure after the primary separator separates a part of the solvent. 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 gas container and the secondary gas container, and after remixing, use it for reinjection. The crude oil collection container is used to collect the mixed system containing crude oil separated by the primary separator and the secondary separator in sequence.

[0019] According to a specific embodiment of the present invention, preferably, the above system further includes a data acquisition and processing device, which is communicatively connected to the first gas / liquid interface probe, the second gas / liquid interface probe, the first pressure sensor, the second pressure sensor and the third pressure sensor, and is used to collect, monitor and process data detected by the gas / liquid interface probe and the pressure sensor. Generally speaking, the data acquisition and processing device may include equipment such as a data collector and a computer. The communication connection may include an electrical connection.

[0020] In the above system, preferably, valves are respectively provided on 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, and the first injection mechanism is used to inject the mixed system 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 first-stage 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 primary separator.

[0026] In the above system, preferably, valves are respectively provided on 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, and the second injection mechanism is used to inject the mixed system containing crude oil and solvent obtained after the primary separator separates a part of the solvent 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] The present invention respectively arranges gas / liquid interface probes in the primary separator and the secondary separator to detect the interface between gas and liquid, and utilizes the difference between the resistivity of gas and liquid, and feeds back the difference to the control software in the data acquisition and processing device, so as to realize timely monitoring and determination of the gas-liquid interface. After the gas / liquid interface probe detects the gas / liquid interface, liquid can be discharged through the liquid outlets of the primary separator and the secondary separator to control the height of the gas / liquid interface within a suitable range, prevent liquid accumulation or liquid overflow in the separator, and prevent gas from escaping from the liquid outlet at the bottom of the separator.

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

[0034] In the above system, preferably, a first gas mass flow controller is provided on the pipeline connecting the primary separator and the primary gas container, at least for measuring the flow of the gaseous solvent separated by the primary 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, at least for measuring the flow of the gaseous solvent separated by the secondary separator.

[0036] In the above system, preferably, the number of injection ports of the piston-type gas collector is 2, which are respectively connected to the exhaust port of the primary gas container and the exhaust port of the secondary gas container through 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, the piston located at the bottom of the inner cavity of the piston-type gas collector is pushed upward, and the piston divides the cavity of the piston-type gas collector into a pressure regulating cavity at the upper part of the piston and a solvent cavity at the lower part of the piston. It can be understood by those skilled in the art that one end of the discharge pipeline in the piston-type gas collector should extend into the solvent cavity, and the other end of the discharge pipeline 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 arranged on the top of the piston-type gas collector and is used to adjust the pressure in the solvent chamber through the pressure regulating chamber by using the pressure regulating valve.

[0040] In the above system, preferably, a compressor is provided on the pipeline connected to the discharge port of the piston type gas collector, for pressurizing the solvent to the injection pressure.

[0041] In the above system, preferably, a third gas mass flow controller is provided on the pipeline connected to the discharge port 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 provided behind the compressor.

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

[0043] The second aspect of the present invention provides an experimental system for closed-cycle separation and reinjection of solvents, which includes the above-mentioned closed-cycle separation and reinjection system of solvents, and an experimental model; the experimental model is at least provided with an injection port and an exhaust port, the injection port is arranged at the top of the experimental model, and the exhaust port is arranged at the bottom of the experimental model; the exhaust port of the experimental model is connected to the injection port of the primary separator through a pipeline; the injection port of the experimental model is connected to the exhaust port of the piston-type gas collector through a pipeline.

[0044] According to a specific embodiment of the present invention, the experimental model may use a high-temperature and high-pressure gas-liquid separator. The high-temperature and high-pressure gas-liquid separator may use a conventional device in the art, and the present invention does not specifically limit its specific structure.

[0045] In the above experimental system, preferably, valves are respectively provided on the pipelines connected to the injection port and the discharge port of the experimental model to control the injection of the solvent and the discharge of the mixed system containing crude oil and the solvent.

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

[0047] A third aspect of the present invention provides a method for solvent closed cycle separation and reinjection, the method using the above-mentioned solvent closed cycle separation and reinjection system, the method comprising the following steps:

[0048] (1) allowing a mixed system of crude oil and solvent produced from an oil reservoir to enter a primary separator, using a first gas / liquid interface probe to monitor the gas-liquid interface in real time, and allowing the pressure in the primary separator to reach P1;

[0049] (2) After the pressure in the primary separator reaches P1, the gaseous solvent is discharged from the top of the primary separator and enters the primary gas container, and the mixed system containing crude oil and solvent is discharged from the bottom of the primary separator and enters the secondary separator;

[0050] (3) using a second gas / liquid interface probe to monitor the gas-liquid interface in the secondary separator in real time, and when the gas-liquid interface in the secondary separator reaches more than 1 / 3 of the height of the inner cavity of the secondary separator, 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, and the pressure in the secondary separator is P2;

[0051] (4) adjusting the pressure in the piston-type gas collector in real time so that the gaseous solvent discharged from the primary gas container and the secondary gas container all enters the piston-type gas collector;

[0052] (5) The gaseous solvent discharged from the piston gas collector is pressurized and liquefied and then re-injected into the oil reservoir.

[0053] In the above method, preferably, the solvent includes one or a combination of C1-C10 light alkanes, C6-C10 light aromatics, alcohols below C10, aldehydes below C10, ethers below C10 and ketones below 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 gas / liquid interface height to be less than 1 / 5 of the inner cavity height of the primary 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 saturated vapor pressure of the solvent under the temperature conditions in the primary separator.

[0056] In the above method, preferably, in step (1), the temperature in the primary separator is above the highest flash point temperature of one or a combination of C1-C5 light alkanes, alcohols below C5, aldehydes below C5, ethers below C5 and ketones below C5. More preferably, the temperature in 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 saturated vapor pressure of the solvent 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 a combination of C6-C10 light alkanes, C6-C10 light aromatics, C6-C10 alcohols, C6-C10 aldehydes, C6-C10 ethers and C6-C10 ketones.

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

[0060] According to a specific embodiment of the present invention, the first pressure sensor and the second pressure sensor arranged at the top of the first separator and the second separator can be used to detect the pressure inside the first separator and the second separator in real time, and the valves arranged on the pipelines connecting the gas outlets at the top of the first separator and the second separator can be used to control and adjust the pressure inside the first separator and the second separator in real time 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 enters the primary gas container after being metered by the first gas mass flow controller to a flow rate of Q1.

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

[0063] In the above method, preferably, in step (4), the pressure of the solvent chamber of the piston-type gas collector is adjusted in real time by the pressure regulating valve on the top of the piston-type gas collector, and the gaseous solvents discharged from the primary gas container and the secondary gas container both enter the solvent chamber of the piston-type 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 oil 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 the gaseous solvent discharged from the piston-type gas collector is pressurized and liquefied by the compressor is 0.5-1.0 MPa above the saturated vapor pressure of the solvent. The pressure of the pressurized and liquefied solvent is the injection pressure.

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

[0067] In the above method, preferably, the pressure of 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.

[0068] In the above method, preferably, the pressure of the solvent chamber of the piston-type 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 of 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 the primary gas container and the secondary gas container can enter the piston-type gas collector, it is necessary to control P5 to be less than or equal to P3 and P4. At the same time, the pressure at the outlet of the compressor is P7. To ensure that the gaseous solvent in the piston-type gas collector can enter the compressor, it is necessary to control the pressure P7 at the outlet of the compressor to be greater than or equal to the pressure P5 of the solvent chamber of the piston-type gas collector (this pressure is also the inlet pressure of the compressor). It is necessary to adjust the pressure P5 of the solvent chamber of the piston-type gas collector so that it satisfies the above conditions at the same time, that is, P5 needs to be less than or equal to P3, P4 and P7. The pressure P5 of the solvent chamber of the piston-type gas collector is completed by the pressure regulating valve at the top of the piston-type gas collector. The pressure regulating valve timely adjusts the pressure P6 in the upper pressure regulating chamber by releasing gas, so that P5 satisfies the above conditions at the same time. By adjusting the pressure P5 of 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 comprises step (7): weighing the weight of the mixed system containing crude oil in the crude oil collection container in real time by a weighing device.

[0071] A fourth aspect of the present invention provides an experimental method for solvent closed cycle separation and reinjection, the method is carried out using the above-mentioned solvent closed cycle separation and reinjection experimental system, and the method comprises the following steps:

[0072] (1) allowing a mixed system containing crude oil and solvent in an experimental model to enter a primary separator, using a first gas / liquid interface probe to monitor the gas-liquid interface in real time, and allowing the pressure in the primary separator to reach P1;

[0073] (2) After the pressure in the primary separator reaches P1, the gaseous solvent is discharged from the top of the primary separator and enters the primary gas container, and the mixed system containing crude oil and solvent is discharged from the bottom of the primary separator and enters the secondary separator;

[0074] (3) using a second gas / liquid interface probe to monitor the gas-liquid interface in the secondary separator in real time, and when the gas-liquid interface in the secondary separator reaches more than 1 / 3 of the height of the inner cavity of the secondary separator, 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, and the pressure in the secondary separator is P2;

[0075] (4) adjusting the pressure in the piston-type gas collector in real time so that the gaseous solvent discharged from the primary gas container and the secondary gas container all enters the piston-type gas collector;

[0076] (5) The gaseous solvent discharged from the piston-type gas collector is pressurized and liquefied, and then re-injected into the experimental model.

[0077] In the above experimental method, preferably, the solvent includes one or a combination of C1-C10 light alkanes, C6-C10 light aromatics, 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 gas / liquid interface height to be less than 1 / 5 of the inner cavity height of the first 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 saturated vapor pressure of the solvent under the temperature conditions in the primary separator.

[0080] In the above experimental method, preferably, in step (1), the temperature in the primary separator is above the highest flash point temperature of one or a combination of C1-C5 light alkanes, alcohols below C5, aldehydes below C5, ethers below C5 and ketones below C5. More preferably, the temperature in 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 a combination of C6-C10 light alkanes, C6-C10 light aromatics, C6-C10 alcohols, C6-C10 aldehydes, C6-C10 ethers and C6-C10 ketones.

[0083] According to a specific embodiment of the present invention, the first pressure sensor and the second pressure sensor arranged at the top of the first separator and the second separator can be used to detect the pressure inside the first separator and the second separator in real time, and the valves arranged on the pipelines connecting the gas outlets at the top of the first separator and the second separator can be used to control and adjust the pressure inside the first separator and the second separator in real time 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 enters the primary gas container after being metered by the first gas mass flow controller to a flow rate of Q1.

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

[0086] In the above-mentioned experimental method, preferably, in step (4), the pressure of the solvent chamber of the piston-type gas collector is adjusted in real time by the pressure regulating valve on the top of the piston-type gas collector, and the gaseous solvents discharged from the primary gas container and the secondary gas container both enter the solvent chamber of the piston-type 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-type gas collector is pressurized and liquefied by a compressor is 0.5-1.0 MPa above the saturated vapor pressure of the solvent.

[0089] In the above experimental method, preferably, the pressure of 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 of the solvent chamber of the piston-type 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 comprises step (6): calculating the real-time solvent reinjection rate by real-time monitoring of Q1, Q2 and Q3, the solvent reinjection rate = (Q1+Q2)×100% / Q3.

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

[0093] The present invention provides a system and method for solvent closed cycle separation and reinjection, and an experimental system and experimental method for solvent closed cycle separation and reinjection. The present invention can realize accurate simulation of solvent cycle injection and production, and realize accurate measurement of solvent closed separation and solvent reinjection rate.

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

[0095] (1) The present invention adopts a two-stage separator to achieve online separation of mixed solvents with different flash points. Among them, the first-stage separator is used to separate low-flash-point solvents under pressure, and the second-stage separator is used to separate high-flash-point solvents. Through two-stage separation, the separation efficiency of solvents from produced crude oil can be greatly improved. In addition, the second-stage separator of the present invention further has the function of heating, and the speed and efficiency of separating high-flash-point solvents from crude oil can be further improved by heating. The total solvent separation efficiency of the present invention can reach more than 98%.

[0096] (2) The gas-liquid interface inside the primary separator and the secondary separator can be detected in a timely manner to prevent the 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 can timely measure the amount of solvent produced by the piston-type gas collector, and compare and calculate it with the amount of solvent injected, so as to obtain the timely solvent reinjection rate.

[0098] The system and method of the present invention can realize the closed cycle separation and reinjection of solvent in the process of solvent injection development of heavy oil and super heavy oil reservoirs, can realize the circulating solvent injection, and thus can improve the crude oil recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0099] Figure 1 A schematic diagram of the structure of a system for closed-loop separation and reinjection of solvents provided in one embodiment of the present invention.

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

[0101] Figure 3 A schematic diagram of the structure of an experimental system for closed-loop separation and reinjection of solvents provided in one specific embodiment of the present invention.

[0102] Description of Figure 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-type 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 pipeline; 602 - piston; 603 - third pressure sensor; 604 - pressure regulating chamber; 605 - solvent chamber; 606 - pressure regulating valve. DETAILED DESCRIPTION

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

[0109] Example 1

[0110] This embodiment provides a solvent closed cycle separation and reinjection system, the structure of which is as follows: Figure 1 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 Also shown is an oil reservoir 1.

[0113] Among them, the first-level separator 2 is at least provided with an injection port, a liquid discharge port, a gas discharge port, a first injection mechanism 201, a first gas / liquid interface probe 202, and a first pressure sensor 203; the injection port and the liquid discharge port are arranged at the bottom of the first-level separator 2; the gas discharge port is arranged at the top of the first-level separator 2; the first injection mechanism 201 is arranged in the cavity of the first-level separator 2 and is connected with the injection port; the first gas / liquid interface probe 202 is arranged in the cavity of the first-level separator 2; the first pressure sensor 203 is arranged on the pipeline connected with the gas discharge port, and is used to detect the pressure inside the first-level separator 2.

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

[0115] The pipelines connected to the liquid outlet and the gas outlet of the first-stage separator 2 are respectively provided with valves. The pipeline connected to the injection port of the first-stage separator 2 is also provided with a valve.

[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 mixed system containing crude oil and solvent into the primary separator 2 from bottom to top. In addition, 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 1 / 2 of the height of the inner cavity of the primary separator 2 .

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

[0119] The first gas / liquid interface probe 202 is disposed 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 primary separator 2 .

[0121] The injection port of the primary separator 2 is used to allow the mixed system containing crude oil and solvent produced by the oil reservoir 1 to enter the primary separator 2. The liquid discharge port of the primary separator 2 is connected to the injection port of the secondary separator 3 through a pipeline.

[0122] The gas outlet of the primary separator 2 is connected to the injection port of the primary gas container 4 through a pipeline.

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

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

[0125] The secondary separator 3 is used to achieve secondary separation of the solvent in the mixed system containing crude oil and solvent obtained after a part of the solvent is separated by the primary separator 2, with or without pressure.

[0126] Valves are respectively provided on the pipelines connected to the liquid outlet and the 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 mixed system containing crude oil and solvent obtained after a part of the solvent is separated by the primary separator 2 into the secondary separator 3 from bottom to top. In addition, 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 1 / 2 of 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 injection port of the secondary gas container 5 through a pipeline.

[0133] In this embodiment, gas / liquid interface probes are respectively set in the first-stage separator 2 and the second-stage separator 3 to detect the interface between the gas and the liquid. By utilizing the difference in resistivity between the gas and the liquid and feeding back the difference to the control software in the data acquisition and processing device 7, timely monitoring and judgment of the gas-liquid interface can be achieved.

[0134] In this embodiment, the first pressure sensor 203 and the second pressure sensor 303 arranged at the top of the first separator 2 and the second separator 3 can detect the pressure inside the first separator 2 and the second separator 3 in real time, and the valves arranged on the pipelines connecting the gas outlets at the top of the first separator 2 and the second separator 3 can control and adjust the pressure inside the first separator 2 and the second separator 3 in real time to achieve dynamic pressure balance.

[0135] The primary gas container 4 is provided with at least an injection port and an exhaust port. 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 provided with at least an injection port and an exhaust port. 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 provided with at least an injection port, an exhaust port, an exhaust pipeline 601, a piston 602, and a third pressure sensor 603; the injection port is provided at the bottom of the piston-type gas collector 6; the exhaust port is provided at the top of the piston-type gas collector 6; the exhaust pipeline 601 is provided in the cavity of the piston-type gas collector 6 and is connected with the exhaust port; the piston 602 is provided in the cavity of the piston-type gas collector 6; the third pressure sensor 603 is provided on the pipeline connected with the exhaust port, 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 solvents from the primary gas container 4 and the secondary gas container 5, and remix them for reinjection.

[0138] The number of injection ports of the piston-type gas collector 6 is two, which are respectively connected to the discharge port of the primary gas container 4 and the discharge port of the secondary gas container 5 through pipelines. The pipelines connected to the two injection ports of the piston-type gas collector 6 are respectively provided with valves.

[0139] When the gaseous solvent from the primary gas container 4 and the secondary gas container 5 is injected into the piston-type gas collector 6, the piston 602 located at the bottom of the inner cavity of the piston-type gas collector 6 is pushed upward, and the piston 602 divides the cavity of the piston-type gas collector 6 into a pressure regulating cavity 604 at the upper part of the piston 602 and a solvent cavity 605 at the lower part of the piston 602. It can be understood by those skilled in the art that one end of the discharge pipeline 601 in the piston-type gas collector 6 should extend into the solvent cavity 605, and the other end of the discharge pipeline 601 is connected to the discharge port of the piston-type gas collector 6.

[0140] The piston-type gas collector 6 is also provided with a pressure regulating valve 606, which is arranged at the top of the piston-type gas collector 6 and is used to use the pressure regulating valve 606 to adjust the pressure in the solvent chamber 605 through the pressure regulating chamber 604. The pressure in the solvent chamber 605 can be adjusted in time through the pressure regulating valve 606 and the pressure regulating chamber 604 to achieve dynamic balance control and mixing of the 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 probe and the pressure sensor. In this embodiment, the data acquisition and processing device 7 may include equipment such as a data acquisition device and a computer. The communication connection may include an electrical connection. Among them, the schematic diagram of the communication connection between the first gas / liquid interface probe 202 and the first pressure sensor 203 of the primary separator 2 and the data acquisition and processing device 7 is shown in FIG. Figure 2 shown.

[0142] The crude oil collection container 8 is connected to the liquid discharge port of the secondary separator 3 through a pipeline. The crude oil collection container 8 is used to collect the mixed system containing crude oil separated 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 a beaker.

[0143] The weighing device 9 is used to weigh the weight of the mixed system 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 and the like.

[0144] A first gas mass flow controller 10 is provided on the pipeline connecting the primary separator 2 and the primary gas container 4 , for real-time metering and controlling the mass and volume flow of the gaseous solvent separated by the primary separator 2 .

[0145] A second gas mass flow controller 11 is provided on the pipeline connecting the secondary separator 3 and the secondary gas container 5 , for real-time metering and controlling the mass and volume flow of the gaseous solvent separated by the secondary separator 3 .

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

[0147] A third gas mass flow controller 12 is provided on the pipeline connected to the discharge port of the piston gas collector 6 for real-time metering and controlling the mass and volume flow of the reinjected solvent. In addition, the third gas mass flow controller 12 is provided behind the compressor 13 .

[0148] The discharge port of the piston-type gas collector 6 is connected to the solvent injection port of the oil reservoir 1 through a pipeline, a compressor 13, a third gas mass flow controller 12 and a valve, etc., to achieve closed-loop separation and reinjection of the solvent.

[0149] Example 2

[0150] This embodiment provides a method for solvent closed cycle separation and reinjection, which adopts the solvent closed cycle separation and reinjection system provided in Example 1, and comprises the following steps:

[0151] (1) a mixed system of crude oil and solvent produced from the oil reservoir 1 is allowed to enter the primary separator 2, and the gas-liquid interface is monitored in real time by 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 primary separator 2, and the pressure in the primary separator 2 reaches P1, where P1 is 0.5 to 1 MPa below the saturated vapor pressure of the solvent under the temperature conditions in the primary separator 2, and the temperature in the primary separator 2 is above the highest flash point temperature of one or a combination of C1-C5 light alkanes, C5 or less alcohols, C5 or less aldehydes, C5 or less ethers, and C5 or less ketones, preferably 20 to 30° C.;

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

[0153] (3) using the second gas / liquid interface probe 302 to monitor the gas-liquid interface in the secondary separator 3 in real time, 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 secondary gas-liquid separation, the pressure in the secondary separator 3 is P2, P2 is 0.5-1 MPa below the saturated vapor pressure of the solvent under the normal pressure or the temperature condition in the secondary separator 3, the temperature in the secondary separator is higher than the highest flash point temperature of one or a combination of C6-C10 light alkanes, C6-C10 light aromatics, C6-C10 alcohols, C6-C10 aldehydes, C6-C10 ethers and C6-C10 ketones, the gaseous solvent discharged from the top of the secondary separator 3 enters the secondary gas container 5 after the flow rate is Q2 through the second gas mass flow controller 11, and 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-type gas collector 6 is adjusted in real time by the pressure regulating valve 606 at the top of the piston-type 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-type gas collector 6;

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

[0156] (6) The real-time solvent reinjection rate is calculated by real-time monitoring of Q1, Q2 and Q3: Solvent reinjection rate = (Q1 + Q2) × 100% / Q3.

[0157] The solvent includes one or a combination of C1-C10 light alkanes, C6-C10 light aromatics, 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 set at the top of the first separator 2 and the second separator 3 can be used to detect the pressure inside the first separator 2 and the second separator 3 in real time, and the valves set on the pipelines connecting the gas outlets at the top of the first separator 2 and the second separator 3 can be used to control and adjust the pressure inside the first separator 2 and the second separator 3 in real time to achieve dynamic pressure balance.

[0159] In this embodiment, the pressure of 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, it is necessary to control P5 to be less than or equal to P3 and P4. At the same time, the pressure at the outlet of the compressor 13 is P7. To ensure that the gaseous solvent in the piston-type gas collector 6 can enter the compressor 13, it is necessary to control the pressure P7 at the outlet of the compressor 13 to be greater than or equal to the pressure P5 of the solvent chamber 605 of the piston-type gas collector 6 (this pressure is also the inlet pressure of the compressor 13). It is necessary to adjust the pressure P5 of the solvent chamber 605 of the piston-type gas collector 6 so that it satisfies the above conditions at the same time, that is, P5 needs to be less than or equal to P3, P4 and P7. The pressure P5 of the solvent chamber 605 of the piston-type gas collector 6 is achieved by the pressure regulating valve 606 at the top of the piston-type gas collector 6. The pressure regulating valve 606 timely adjusts the pressure P6 in the upper pressure regulating chamber 604 by releasing gas, so that P5 satisfies the above conditions at the same time. By adjusting the pressure P5 of the solvent chamber 605 of the piston-type gas collector 6 in real time, dynamic balance control and mixing of the gaseous solvent before reinjection can be achieved.

[0160] In this embodiment, the method further comprises step (7): weighing and recording the weight of the mixed system containing crude oil in the crude oil collection container 8 in real time by means of a weighing device 9 .

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

[0162] Example 3

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

[0164] The experimental system includes the solvent closed cycle separation and reinjection system provided in Example 1, and an experimental model 101; the experimental model 101 is at least provided with an injection port and an outlet, the injection port is provided at the top of the experimental model 101, and the outlet is provided at the bottom of the experimental model 101; the outlet 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 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] The valves arranged on the pipelines connected to the injection port and the discharge port of the experimental model 101 are used to control the injection of the solvent and the discharge of the mixed system containing the crude oil and the solvent, respectively.

[0166] The experimental model 101 may use a high temperature and high pressure gas-liquid separator. The high temperature and high pressure gas-liquid separator may use a conventional device in the art, and the present invention does not specifically limit its specific structure.

[0167] The height of the first gas / liquid interface probe 202 is ½ of the height of the inner cavity of the primary separator 2 , and the height of the second gas / liquid interface probe 302 is ½ of the height of the inner cavity of the secondary separator 3 .

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

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

[0170] The experimental method includes the following steps:

[0171] (1) setting an outlet back pressure for the experimental model 101, and allowing the mixed system containing crude oil and solvent in the experimental model 101 to enter the primary separator 2 under the control of the back pressure, and using the first gas / liquid interface probe 202 to monitor the gas-liquid interface in real time, so as to control the height of the gas / liquid interface to be less than 1 / 5 of the inner cavity height of the primary separator 2, and to make the pressure in the primary separator 2 reach P1, where P1 is 0.5 MPa below the saturated vapor pressure of the solvent under the temperature condition in the primary separator 2, and the temperature in the primary separator 2 is 20-30° C.;

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

[0173] (3) using the second gas / liquid interface probe 302 to monitor the gas-liquid interface in the secondary separator 3 in real time, 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 secondary gas-liquid separation, the pressure in the secondary separator 3 is P2, P2 is 0.5 MPa below the saturated vapor pressure of the solvent under the temperature condition in the secondary separator 3, the temperature in the secondary separator 3 is 124° C., the gaseous solvent discharged from the top of the secondary separator 3 passes through the second gas mass flow controller 11 to measure the flow rate to Q2, and then enters the secondary gas container 5, and 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-type gas collector 6 is adjusted in real time by the pressure regulating valve 606 at the top of the piston-type 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-type gas collector 6;

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

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

[0177] (7) The weight of the mixed system containing crude oil in the crude oil collection container 8 is measured and recorded in real time by the weighing device 9.

[0178] This embodiment realizes the closed circulation, separation and injection of solvent, and the overall separation efficiency reaches 99%. Among them, the cumulative injection volume Q3 is 20L, the cumulative output volume Q1 is 16.6L, Q2 is 2.1L, and the cumulative solvent circulation re-injection rate is 93.5%.

[0179] Example 4

[0180] This embodiment provides an experimental system for closed-loop separation and reinjection of a solvent, the structure of which 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 separation and reinjection of a solvent, which is basically the same as that of 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 realizes the closed circulation, separation and injection of solvent, and the overall separation efficiency reaches 99%. Among them, the cumulative injection volume is Q3 is 20L, the cumulative output volume is Q1 is 17.6L, Q2 is 1.0L, and the cumulative solvent circulation re-injection rate is 18.6 / 20=93%.

Claims

1. A solvent closed cycle separation and reinjection system, comprising: Primary separator, secondary separator, primary gas container, secondary gas container, crude oil collection container, piston type gas collector; Wherein, the primary separator is at least provided with an injection port, a liquid discharge port, a gas discharge port, a first injection mechanism, a first gas / liquid interface probe, and a first pressure sensor; the injection port and the liquid discharge port are arranged at the bottom of the primary separator; the gas discharge port is arranged at the top of the primary separator; the first injection mechanism is arranged in the cavity of the primary separator and is communicated with the injection port; the first gas / liquid interface probe is arranged in the cavity of the primary separator; the first pressure sensor is arranged on the pipeline communicated with the gas discharge port, and is used to detect the pressure inside the primary separator; The secondary separator is at least provided with an injection port, a liquid discharge port, a gas discharge port, a second injection mechanism, a second gas / liquid interface probe, and a second pressure sensor; the injection port and the liquid discharge port are arranged at the bottom of the secondary separator; the gas discharge port is arranged at the top of the secondary separator; the second injection mechanism is arranged in the cavity of the secondary separator and is connected with the injection port; the second gas / liquid interface probe is arranged in the cavity of the secondary separator; the second pressure sensor is arranged on the pipeline connected with the gas discharge port, and is used to detect the pressure inside the secondary separator; The primary gas container is provided with at least an injection port and an exhaust port; The secondary gas container is provided with at least an injection port and an exhaust port; The piston-type gas collector is at least provided with an injection port, a discharge port, a discharge pipeline, a piston, and a third pressure sensor; the injection port is provided at the bottom of the piston-type gas collector; the discharge port is provided at the top of the piston-type gas collector; the discharge pipeline is provided in the cavity of the piston-type gas collector and is communicated with the discharge port; the piston is provided in the cavity of the piston-type gas collector; the third pressure sensor is provided on the pipeline communicated with the discharge port, and is used to detect the pressure inside the piston-type gas collector; The injection port of the primary separator is used to allow the mixed system containing crude oil and solvent to enter the primary separator; The liquid outlet of the primary separator is connected to the injection port of the secondary separator through a pipeline; The gas outlet of the primary separator is connected to the injection port of the primary gas container through a pipeline; The gas outlet of the secondary separator is connected to the injection port of the secondary gas container through a pipeline; The discharge port of the primary gas container and the discharge port of the secondary gas container are connected to the injection port of the piston type gas collector through pipelines; The crude oil collection container is connected to the liquid discharge port of the secondary separator through a pipeline.

2. The solvent closed cycle separation and reinjection system according to claim 1, wherein: The system further includes a data acquisition and processing device, which is communicatively connected to the first gas / liquid interface probe, the second gas / liquid interface probe, the first pressure sensor, the second pressure sensor and the third pressure sensor, and is used to collect, monitor and process data detected by the gas / liquid interface probe and the pressure sensor.

3. The solvent closed cycle separation and reinjection system according to claim 1, wherein: 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, and the first injection mechanism is used to inject the mixed system containing crude oil and solvent into the primary separator from bottom to top; Preferably, the first injection mechanism is arranged perpendicular to the bottom surface of the primary separator; Preferably, 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.

4. The solvent closed cycle separation and reinjection system according to claim 1 or 3, wherein: The first gas / liquid interface probe is a resistance probe; Preferably, the first gas / liquid interface probe is arranged in parallel with the first injection mechanism; 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 primary separator.

5. The solvent closed cycle 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, and the second injection mechanism is used to inject the mixed system containing crude oil and solvent obtained after the primary separator separates a part of the solvent into the secondary separator from bottom to top; Preferably, the second injection mechanism is arranged perpendicular to the bottom surface of the secondary separator; 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.

6. The solvent closed cycle separation and reinjection system according to claim 1 or 5, wherein: The second gas / liquid interface probe is a resistance probe; Preferably, the second gas / liquid interface probe is arranged in parallel with the second injection mechanism; 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.

7. The solvent closed cycle separation and reinjection system according to claim 1, wherein: A heating jacket is arranged outside the secondary separator.

8. The solvent closed cycle separation and reinjection system according to claim 1, wherein: A first gas mass flow controller is provided on the pipeline connecting the first-stage separator and the first-stage gas container, and is at least used to measure the flow of the gaseous solvent separated by the first-stage separator; Preferably, a second gas mass flow controller is provided on the pipeline connecting the secondary separator and the secondary gas container, at least for measuring the flow of the gaseous solvent separated by the secondary separator.

9. The solvent closed cycle separation and reinjection system according to claim 1, wherein: When the gaseous solvent from the primary gas container and the secondary gas container is injected into the piston-type gas collector, the piston located at the bottom of the inner cavity of the piston-type gas collector is pushed upward, and the piston divides the cavity of the piston-type gas collector into a pressure regulating cavity at the upper part of the piston and a solvent cavity at the lower part of the piston; Preferably, the piston-type gas collector is further provided with a pressure regulating valve, which is arranged on the top of the piston-type gas collector and is used to adjust the pressure in the solvent chamber through the pressure regulating chamber by using the pressure regulating valve.

10. The solvent closed cycle separation and reinjection system according to claim 1, wherein: A compressor is arranged on the pipeline connected to the discharge port of the piston type gas collector, so as to pressurize the solvent to the injection pressure.

11. The solvent closed cycle separation and reinjection system according to claim 1, wherein: A third gas mass flow controller is arranged on the pipeline connected to the discharge port of the piston-type gas collector, and is at least used to measure the flow rate of the reinjected solvent.

12. A method for solvent closed cycle separation and reinjection, the method using the solvent closed cycle separation and reinjection system according to any one of claims 1 to 11, the method comprising the following steps: (1) allowing a mixed system of crude oil and solvent produced from an oil reservoir to enter a primary separator, using a first gas / liquid interface probe to monitor the gas-liquid interface in real time, and allowing the pressure in the primary separator to reach P1; (2) After the pressure in the primary separator reaches P1, the gaseous solvent is discharged from the top of the primary separator and enters the primary gas container, and the mixed system containing crude oil and solvent is discharged from the bottom of the primary separator and enters the secondary separator; (3) using a second gas / liquid interface probe to monitor the gas-liquid interface in the secondary separator in real time, and when the gas-liquid interface in the secondary separator reaches more than 1 / 3 of the height of the inner cavity of the secondary separator, 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, and the pressure in the secondary separator is P2; (4) adjusting the pressure in the piston-type gas collector in real time so that the gaseous solvent discharged from the primary gas container and the secondary gas container all enters the piston-type gas collector; (5) The gaseous solvent discharged from the piston gas collector is pressurized and liquefied and then re-injected into the oil reservoir.

13. The method for solvent closed cycle separation and reinjection according to claim 12, wherein: The solvent includes one or a combination of C1-C10 light alkanes, C6-C10 light aromatics, alcohols below C10, aldehydes below C10, ethers below C10 and ketones below C10.

14. The method for solvent closed cycle separation and reinjection according to claim 12, wherein: In step (1), the pressure P1 in the primary separator is 0.5 to 1 MPa below the saturated vapor pressure of the solvent under the temperature conditions in the primary separator; Preferably, in step (1), the temperature in the primary separator is above the highest flash point temperature of one or a combination of C1-C5 light alkanes, C5 or lower alcohols, C5 or lower aldehydes, C5 or lower ethers and C5 or lower ketones; more preferably, the temperature in the primary separator is 20-30°C; 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; Preferably, in step (3), the temperature in the secondary separator is above the highest flash point temperature of one or a combination of C6-C10 light alkanes, C6-C10 light aromatics, C6-C10 alcohols, C6-C10 aldehydes, C6-C10 ethers and C6-C10 ketones.

15. The method for solvent closed cycle separation and reinjection according to claim 12, wherein: In step (2), the gaseous solvent discharged from the top of the primary separator enters the primary gas container after being metered by the first gas mass flow controller to a flow rate of Q1; In step (3), the gaseous solvent discharged from the top of the secondary separator enters the secondary gas container after being metered by the second gas mass flow controller to a flow rate of Q2; In step (5), the gaseous solvent discharged from the piston-type gas collector is pressurized and liquefied by a compressor, and then the liquid solvent is re-injected into the oil reservoir after the flow rate is measured to Q3 by a third gas mass flow controller.

16. The method for solvent closed cycle separation and reinjection according to claim 12, wherein: In step (4), the pressure of the solvent chamber of the piston-type gas collector is adjusted in real time by the pressure regulating valve on the top of the piston-type gas collector, and the gaseous solvents discharged from the primary gas container and the secondary gas container all enter the solvent chamber of the piston-type gas collector.

17. The method for solvent closed cycle separation and reinjection according to claim 15, wherein: The above method further comprises step (6): calculating the real-time solvent reinjection rate by real-time monitoring Q1, Q2 and Q3, the solvent reinjection rate = (Q1+Q2)×100% / Q3.

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