A novel CO 2 Miscible pressure testing and displacement system and method for crude oil

Abstract

The present invention discloses a novel miscible pressure testing and displacement system and method for CO2 and crude oil. The system of the present invention can test the minimum miscible pressure of different gases, crude oils, or those containing agents simultaneously under certain formation temperature and pressure conditions, observe and record the miscible process, and simultaneously carry out the displacement oil production processes of gases, crude oils, or those containing agents simultaneously. The setting of the observation window of the present invention can visually observe and record the miscible process. The setting of the stirring device in the fourth piston container can enable the crude oil, gas, and agent for reducing the miscible pressure to be fully mixed, thus avoiding test errors. The setting of the temperature control box and the back pressure valve can precisely control the temperature and pressure, thereby making the test results more accurately measured. The setting of the safety valve can better control the research process, reduce potential safety hazards, and bring great convenience to the development of the research.

Description

Technical Field

[0001] The present invention relates to the technical fields of miscible pressure testing of CO 2 with crude oil and other substances and oil and gas exploitation technology, and particularly relates to a novel miscible pressure testing and displacement system and method of CO 2 with crude oil. Background Art

[0002] Similar miscible pressure testing and displacement systems are important instruments mainly used for testing the minimum miscible pressure of gas and crude oil. Generally, the minimum miscible pressure of CO 2 with crude oil is tested through laboratory experiments. Existing similar systems do not consider the influence of agents for reducing miscible pressure and other factors on the effect of reducing miscible pressure, cannot accurately control the temperature and pressure, which brings large errors to the research, cannot test the miscible pressure of the mixed gas and crude oil, and cannot carry out displacement research after miscibility. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems in the related technologies to a certain extent.

[0004] To this end, an embodiment of the present invention provides a novel miscible pressure testing and displacement system and method of CO 2 with crude oil.

[0005] On the one hand, the present invention provides a novel miscible pressure testing and displacement system of CO 2 with crude oil, including:

[0006] A gas injection system, the gas injection system includes at least one gas cylinder, a gas booster pump is arranged on the outlet pipeline of the gas cylinder, a pressure regulating valve is arranged on the outlet pipeline of the gas booster pump, and a first flowmeter is arranged downstream of the pressure regulating valve;

[0007] A liquid injection system, the liquid injection system includes a first piston container, a second piston container, a third piston container and a fourth piston container. The first piston container is arranged in parallel with the pressure regulating valve on the outlet pipeline of the gas booster pump. Crude oil and an agent for reducing miscible pressure are respectively placed in the second piston container and the third piston container. The upper parts of the second piston container and the third piston container are both connected to the upper part of the fourth piston container, and a stirring device is arranged inside the fourth piston;

[0008] A model system arranged downstream of the gas injection system and the liquid injection system. The model system includes an observation window and a core holder arranged in parallel, and a differential pressure sensor is arranged on the pipeline between the inlet and outlet of the core holder;

[0009] A pressure control system, the pressure control system includes a back pressure control device and a manual pump, and the pressure of the back pressure control device and the confining pressure of the core holder are controlled by the manual pump;

[0010] A gas-liquid metering system, the gas-liquid metering system is arranged downstream of the model system and is used for metering the gas-liquid volume flowing out of the outlet end of the core holder;

[0011] A temperature control system, the temperature control system includes a first temperature control box and a second temperature control box, the first temperature control box is arranged outside the liquid injection system, the model system and the pressure control system, and the second temperature control box is arranged outside the gas-liquid metering system;

[0012] A vacuum pumping device, the vacuum pumping device is arranged on a branch of the inlet pipeline of the model system.

[0013] In some embodiments, injection pumps are connected to the lower parts of the first piston container, the second piston container, the third piston container and the fourth piston container.

[0014] In some embodiments, the liquid injection system further includes a fifth piston container with water placed inside, and the fifth piston container is arranged in parallel with the second piston container.

[0015] In some embodiments, the back pressure control device includes a first back pressure valve and a second back pressure valve, the first back pressure valve is arranged at the inlet end of the model system, and the second back pressure valve is arranged at the outlet end of the model system.

[0016] In some embodiments, a first one-way valve is arranged on the pipeline between the first flowmeter and the first back pressure valve.

[0017] In some embodiments, the output end of the manual pump is connected to a buffer tank, a first valve is arranged on the pipeline between the outlet end of the buffer tank and the first back pressure valve, a second valve is arranged on the pipeline between the outlet end of the buffer tank and the second back pressure valve, and a third valve is arranged on the pipeline between the outlet end of the buffer tank and the core holder.

[0018] In some embodiments, the gas-liquid metering system includes a gas-liquid separator, a second flowmeter is arranged at the upper outlet end of the gas-liquid separator, a dryer is arranged between the gas-liquid separator and the second flowmeter, and a graduated glass container is arranged at the lower outlet end of the gas-liquid separator.

[0019] In some embodiments, a second one-way valve is arranged between the dryer and the second flowmeter.

[0020] In some embodiments, a pressure gauge and a thermometer are disposed on the upper portion of the first piston container, the inlet and outlet ends of the model system, the outlet end of the buffer tank, and the inlet end of the gas-liquid separator.

[0021] On the other hand, the present invention proposes a novel CO 2 Miscible pressure test and displacement method with crude oil, including miscible pressure test and displacement process,

[0022] The miscible pressure test includes the following steps:

[0023] (1) Check the air tightness of the system pipeline, adjust the first temperature control box and the second temperature control box to the target temperature, set the first back pressure valve and the second back pressure valve to the target pressure, and then use a vacuum pump to evacuate the system;

[0024] (2) pumping the crude oil and the agent for reducing the miscible pressure respectively placed in the second piston container and the third piston container into the fourth piston container in a certain proportion, stirring them evenly and then pumping them into the observation window;

[0025] (3) Remove the CO in the gas cylinder 2 After being pressurized by the gas booster pump, the gas flows through the pressure regulating valve, the first flow meter and the first check valve in sequence, and then enters the observation window through the first back pressure valve to observe the mixing process and record the pressure when the mixing is achieved;

[0026] The displacement process includes the following steps:

[0027] (1) Check the air tightness of the system pipeline, install the rock sample in the core holder, adjust the first temperature control box and the second temperature control box to the target temperature, set the first back pressure valve and the second back pressure valve to the target pressure, and then use a vacuum pump to evacuate the system;

[0028] (2) pumping the crude oil in the second piston container and the agent for reducing the miscible pressure in the third piston container into the fourth piston container in a certain ratio, stirring them evenly, and then injecting them into the core holder to saturate the core holder;

[0029] (3) Remove the CO in the gas cylinder 2 After being pressurized by the gas booster pump, it flows through the pressure regulating valve, the first flow meter and the first check valve in sequence, and then is injected into the core holder through the first back pressure valve for displacement;

[0030] (4) The gas-liquid metering system is used to measure the gas-liquid volume at the outlet of the core holder and analyze the displacement effect.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] The system of the present invention can test the minimum miscibility pressure of different gases and crude oil under certain formation temperature and pressure conditions, observe and record the miscibility process, and simultaneously conduct displacement research on the gas at the minimum miscibility pressure.

[0033] The setting of the observation window of the present invention can directly observe and record the miscibility process. The setting of the stirring device in the fourth piston container can make the crude oil and the agent for reducing the miscibility pressure fully mixed, thus avoiding test errors. The settings of the temperature control box and the back pressure valve can accurately control the temperature and pressure, making the test results more accurately measured. The setting of the safety valve can better control the research process, reduce potential safety hazards, and bring great convenience to the development of the research.

[0034] The present invention has various functions. By changing parameters, it is not only convenient to study the influencing factors of miscibility, but also can study the sensitivity factors affecting miscibility and displacement effects. Brief Description of the Drawings

[0035] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the following description of the embodiments in conjunction with the drawings, where:

[0036] Figure 1 is a schematic diagram of the miscibility pressure test and displacement system of CO 2 of the present invention with crude oil;

[0037] Description of the Reference Numerals in the Drawings:

[0038] Gas cylinder 1, gas booster pump 2, silent air compressor 3, first safety valve 4, first pressure gauge 5, first thermometer 6, first piston container 7, fifth piston container 8, second piston container 9, third piston container 10, fourth piston container 11, first injection pump 12, first water tank 13, second injection pump 14, second water tank 15, fourth valve 16, pressure regulating valve 17, first flowmeter 18, first check valve 19, first back pressure valve 20, second back pressure valve 21, manual pump 22, buffer tank 23, first valve 24, second valve 25, third valve 26, fourth pressure gauge 27, fourth thermometer 28, third safety valve 29, second pressure gauge 30, second thermometer 31, third pressure gauge 32, third thermometer 33, observation window 34, core holder 35, differential pressure sensor 36, second safety valve 37, gas-liquid separator 38, dryer 39, second check valve 40, second flowmeter 41, glass container 42, fifth pressure gauge 43, fifth thermometer 44, first temperature control box 45, second temperature control box 46. Detailed Description of the Embodiments

[0039] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where like or similar reference numerals denote like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0040] A novel CO 2 miscible pressure test and displacement system and method with crude oil will be described below with reference to the accompanying drawings.

[0041] As Figure 1 shown, the novel CO 2 miscible pressure test and displacement system with crude oil of the present invention includes a gas injection system, a liquid injection system, a model system, a pressure control system, a gas-liquid metering system, a temperature control system, and a vacuum pumping device.

[0042] The gas injection system includes at least one gas cylinder 1. A gas booster pump 2 is provided on the outlet pipeline of the gas cylinder 1. A pressure regulating valve 17 is provided on the outlet pipeline of the gas booster pump 2, and a first flowmeter 18 is provided downstream of the pressure regulating valve 17.

[0043] Specifically, the gas cylinder 1 stores the gas for the miscible pressure test. When testing the miscible pressure of a single type of gas, only one gas cylinder 1 needs to be set. When testing the miscible pressure of a mixture of multiple gases, the number of gas cylinders 1 is set according to the types of gases. A gas booster pump 2 is provided at the outlet end of the gas cylinder 1. The gas is pressurized by the gas booster pump 2 to become high-pressure gas and flows out of the gas cylinder 1. A pressure regulating valve 17 is provided on the outlet pipeline of the gas booster pump 2. The high-pressure gas flows to the first flowmeter 18 after the pressure is regulated by the pressure regulating valve 17, and the first flowmeter 18 measures the amount of the gas flowing out. Since the first flowmeter 18 is a gas flowmeter, the gas flow pressure of the gas flowmeter needs to be within its tolerable range. The gas pressurized by the gas booster pump 2 is high-pressure gas. Therefore, the pressure regulating valve 17 is provided to adjust the gas pressure of the high-pressure gas to an appropriate pressure range so that the first flowmeter 18 measures accurately. Among them, the gas booster pump 2 is mainly used for gas pressurization. A silent air compressor 3 provided at the input end of the gas booster pump 2 provides compressed air for the gas booster pump 2. The gas booster pump 2 uses compressed air as the power source. Taking the gas booster pump 2 as the pressure source, the output gas pressure is proportional to the driving gas source pressure. By adjusting the driving gas source pressure, the corresponding pressurized gas pressure can be obtained. When the driving gas source pressure is balanced with the pressurized gas pressure, the gas booster pump 2 stops pressurizing, and the output gas pressure is stabilized at the pre-adjusted pressure. Therefore, it has the characteristics of explosion-proof, adjustable output pressure, small volume, light weight, simple operation, reliable performance, wide application range, etc.

[0044] The liquid injection system includes a first piston container 7, a second piston container 9, a third piston container 10, and a fourth piston container 11. The first piston container 7 and the pressure regulating valve 17 are arranged in parallel on the outlet pipeline of the gas booster pump 2. The second piston container 9 and the third piston container 10 are respectively filled with crude oil and the agent for reducing the miscibility pressure. The upper parts of the second piston container 9 and the third piston container 10 are both connected to the upper part of the fourth piston container 11, and a stirring device is arranged inside the fourth piston container 11. The lower parts of the first piston container 7, the second piston container 9, the third piston container 10, and the fourth piston container 11 are all connected to an injection pump. Among them, the injection pump includes a first injection pump 12 and a second injection pump 14.

[0045] Specifically, the first piston container 7 and the pressure regulating valve 17 are arranged in parallel, that is, the upper part of the first piston container 7 is connected to the outlet end of the gas booster pump 2. The first piston container 7 is used to store the gas that has been pressurized by the gas booster pump 2 and is in a liquid state. Since the first flowmeter 18 can only measure the flow rate of the gas, when the gas that has been pressurized by the gas booster pump 2 and is in a liquid state can no longer be measured by the first flowmeter 18, at this time, the liquid gas is pumped into the first piston container 7. A first pressure gauge 5 and a first thermometer 6 are arranged on the upper pipeline of the first piston container 7. The first pressure gauge 5 and the first thermometer 6 are used to measure the gas pressure and temperature in the first piston container 7 in real time. The lower part of the first piston container 7 is connected to the first injection pump 12. The first injection pump 12 is a constant-speed and constant-pressure pump. The first injection pump 12 is used to pump the liquid gas in the first piston container 7 into the model system through the fourth valve 16. The amount of the pumped liquid gas is calculated according to the readings of the first pressure gauge 5 and the first thermometer 6 and the parameters of the constant-speed and constant-pressure pump. In addition, a first safety valve 4 is arranged on the branch pipeline of the upper pipeline of the first piston container 7 to automatically relieve pressure when the first piston container 7 is overpressurized.

[0046] The second piston container 9 and the third piston container 10 are respectively used to place crude oil and the agent for reducing the miscibility pressure. The second piston container 9 and the third piston container 10 are arranged in parallel. The lower parts of the second piston container 9 and the third piston container 10 are both connected to the first injection pump 12. The input end of the first injection pump 12 is connected to the first water tank 13. The upper parts of the second piston container 9 and the third piston container 10 are both connected to the upper part of the fourth piston container 11. A stirring device is arranged inside the fourth piston container 11. The lower part of the fourth piston container 11 is connected to the second injection pump 14. The second injection pump 14 is a constant-speed and constant-pressure pump. The input end of the second injection pump 14 is connected to the second water tank 15. The crude oil in the second piston container 9 and the agent for reducing the miscibility pressure in the third piston container 10 are quantitatively pumped into the fourth piston container 11 under the action of the first injection pump 12. The crude oil and the agent for reducing the miscibility pressure are fully stirred and mixed in the fourth piston container 11. The mixture of the crude oil and the agent for reducing the miscibility pressure after stirring is quantitatively pumped into the downstream model system under the action of the second injection pump 14, and the amount of the pumped-in is measured by the second injection pump 14. It can be understood that by changing the type and dosage of the agent for reducing the miscibility pressure in the third piston container 10, the influence of different types and dosages of agents on the miscibility pressure can be investigated using this system. It can be understood that in the miscibility pressure test experiment, if the influence of the agent for reducing the miscibility pressure on the miscibility pressure is not considered, that is, when the proportion of the agent for reducing the miscibility pressure is zero, the crude oil in the second piston container 9 is directly quantitatively pumped into the observation window 34; in the displacement simulation experiment, if the influence of the agent for reducing the miscibility pressure on the displacement experiment is not considered, that is, when the proportion of the agent for reducing the miscibility pressure is zero, the crude oil in the second piston container 9 is directly pumped into the core holder 35 until the core sample is saturated. It can be understood that when the displacement of the crude oil injected by the first injection pump 12 is the same and stable as the displacement of the crude oil flowing out from the outlet end of the core holder 35 through the second back pressure valve 21, the core sample reaches saturation. Among them, the amount of the crude oil flowing out from the second back pressure valve 21 is measured by the glass container 42. In the displacement simulation experiment, if the influence of the agent for reducing the miscibility pressure on the displacement experiment is considered, the crude oil in the second piston container 9 and the agent for reducing the miscibility pressure in the third piston container 10 are quantitatively pumped into the fourth piston container 11 in a certain proportion under the action of the first injection pump 12. The crude oil and the agent for reducing the miscibility pressure are fully stirred and mixed in the fourth piston container 11. The mixture of the crude oil and the agent for reducing the miscibility pressure after stirring is injected into the core holder 35 until the core sample is saturated under the action of the second injection pump 14.

[0047] In addition, during the displacement experiment, when the displacement of the displacing fluid injected from the inlet end of the core holder 35 is equal and stable to the displacement flowing out from the outlet end of the core holder 35 and no oil is displaced, the displacement experiment is completed, and the amount of the injected displacing substance and the substances such as oil, gas, and water displaced are recorded, and the displacement effect is analyzed. Among them, the displacing fluid can be CO 2, water, N 2 , chemical solutions, polymers, etc.

[0048] In some embodiments, the liquid injection system further includes a fifth piston container 8 filled with water internally, and the fifth piston container 8 is arranged in parallel with the second piston container 9. Specifically, the fifth piston container 8 and the second piston container 9 are arranged in parallel, and the water placed in the fifth piston container 8 is used to clean the system after the experiment or for water displacement simulation experiments.

[0049] Both the first injection pump 12 and the second injection pump 14 are double-cylinder constant-speed and constant-pressure pumps, mainly used for the quantitative injection of liquids such as oil and water and liquid CO 2 . The injection displacement of the first injection pump 12 and the second injection pump 14 can be adjusted, and can be injected at a constant displacement or a variable displacement according to the experimental needs. Among them, the variable displacement injection includes, but is not limited to, injection methods with gradually increasing displacement or gradually decreasing displacement. The constant-speed and constant-pressure pump adopts a digital positioning monitoring servo control circuit, enabling the solution to flow precisely under any pressure conditions, making the high-speed flow stable, continuous without pulsation, and operating at a constant speed and constant pressure.

[0050] The first piston container 7, the second piston container 9, the third piston container 10, the fourth piston container 11, and the fifth piston container 8 are all made of 316L stainless steel and processed by vertical universal internal grinding, which is not prone to cross-flow phenomena. Among them, the fourth piston container 11 is mainly used for the mixing of crude oil and agents for reducing the miscibility pressure, and is internally provided with a stirring device with a stirring function. In addition, the piston container is designed with an upper and lower position trigger mechanism. When the piston runs to the two extreme positions, the computer will detect that the piston has moved to the two extreme end positions and realize the automatic replenishment of the fluid in the piston container.

[0051] The model system is arranged downstream of the gas injection system and the liquid injection system. The model system includes an observation window 34 and a core holder 35 arranged in parallel. A differential pressure sensor 36 is arranged on the pipeline between the inlet and outlet of the core holder 35. Pressure gauges and thermometers are arranged at the inlet and outlet ends of the model system.

[0052] Specifically, a second pressure gauge 30 and a second thermometer 31 are provided at the inlet end of the model system. The second pressure gauge 30 and the second thermometer 31 are used to measure the pressure and temperature at the inlet end of the model system in real time. A third pressure gauge 32 and a third thermometer 33 are provided at the outlet end of the model system. The third pressure gauge 32 and the third thermometer 33 are used to measure the pressure and temperature at the outlet end of the model system in real time. The model system includes an observation window 34 and a core holder 35, and the two are arranged in parallel. The observation window 34 is used to test the miscible pressure of the gas. A second safety valve 37 is provided on the branch line of the outlet pipeline of the observation window 34 to automatically relieve pressure when the observation window 34 is overpressured. The core holder 35 is used to conduct displacement simulation experiments. A differential pressure sensor 36 is provided on the pipeline between the inlet and outlet of the core holder 35 to measure the differential pressure at both ends of the core holder 35 in real time. Among them, the observation window 34 is made of imported sapphire glass, which has high pressure resistance, good temperature resistance, and good light transmittance.

[0053] The pressure control system includes a back pressure control device and a manual pump 22. The pressure of the back pressure control device and the confining pressure of the core holder 35 are controlled by the manual pump 22. The back pressure control device includes a first back pressure valve 20 and a second back pressure valve 21. The first back pressure valve 20 is provided at the inlet end of the model system, and the second back pressure valve 21 is provided at the outlet end of the model system. The output end of the manual pump 22 is connected to a buffer tank 23. A first valve 24 is provided on the pipeline between the outlet end of the buffer tank 23 and the first back pressure valve 20. A second valve 25 is provided on the pipeline between the outlet end of the buffer tank 23 and the second back pressure valve 21. A third valve 26 is provided on the pipeline between the outlet end of the buffer tank 23 and the core holder 35.

[0054] Specifically, the back pressure control device is used to control the pressure entering and leaving the model system. The pressure of the back pressure control device is controlled by the manual pump 22. At the same time, the confining pressure of the core holder 35 is controlled by the manual pump 22. The back pressure control device includes a first back pressure valve 20 provided at the inlet end of the model system and a second back pressure valve 21 provided at the outlet end of the model system. The first back pressure valve 20 is used to control the pressure entering the model system, and the second back pressure valve 21 is used to control the pressure leaving the model system. The output end of the manual pump 22 is connected to a buffer tank 23. The outlet end of the buffer tank 23 is connected to the first back pressure valve 20, the second back pressure valve 21, and the core holder 35 through multiple pipelines respectively. A first valve 24 is provided on the pipeline between the outlet end of the buffer tank 23 and the first back pressure valve 20. A second valve 25 is provided on the pipeline between the outlet end of the buffer tank 23 and the second back pressure valve 21. A third valve 26 is provided on the pipeline between the outlet end of the buffer tank 23 and the core holder 35. A fourth pressure gauge 27 and a fourth thermometer 28 are provided at the outlet end of the buffer tank 23. The fourth pressure gauge 27 and the fourth thermometer 28 are used to measure the pressure and temperature at the outlet end of the buffer tank 23 in real time.

[0055] When it is necessary to adjust the pressure of the first back pressure valve 20, open the first valve 24, close the second valve 25 and the third valve 26, and increase or decrease the minimum pressure at which the fluid can pass through the first back pressure valve 20 by means of the manual pump 22; when it is necessary to adjust the pressure at the second back pressure valve 21, open the second valve 25, close the first valve 24 and the third valve 26, and increase or decrease the minimum pressure at which the fluid can pass through the second back pressure valve 21 by means of the manual pump 22; when it is necessary to adjust the confining pressure of the core holder 35, open the third valve 26, close the first valve 24 and the second valve 25, and increase or decrease the confining pressure of the core holder 35 by means of the manual pump 22. In addition, a third safety valve 29 is provided on the branch pipeline of the outlet pipeline of the buffer tank 23 to automatically relieve pressure when the buffer tank 23 is overpressured.

[0056] Among them, the buffer tank 23 is made of high-pressure-resistant stainless steel seamless pipe material, designed according to the GB150 "Pressure Vessels" standard, and the material is selected as 304 stainless steel. It can be understood that other suitable materials can also be used for the buffer tank 23. The back pressure valve adopts a piston structure and is mainly composed of a valve body and a valve core. This valve has the advantages of high adjustment sensitivity, high pressure resistance (above 70 MPa), high control accuracy, and light weight. The upper and lower parts of the valve body are respectively provided with a back pressure interface and a liquid flow inlet and outlet interface. The valve core adopts a piston structure, and a plunger convex head extends axially at the bottom of the piston. A cylindrical hole matching the plunger convex head is prefabricated at the lower part of the valve body. The liquid flow inlet interface and the outlet interface are respectively connected to the bottom of the cylindrical hole of the valve body below the piston convex head through a diversion cavity. An auxiliary liquid flow inlet interface connected to the inlet liquid flow pipe is also provided on one side of the valve body, and the auxiliary liquid flow inlet interface is connected to the joint of the lower part of the valve body and the piston body through a diversion cavity.

[0057] The core holder 35 can be of types such as a long-tube core holder or a common core holder, and is designed and selected according to needs. The core holder 35 is designed with an installation support mechanism. The left end head, measuring point, rubber cylinder, right core plug, right end head, support rod, support ring, lead-out rod, and lead-out sealing mechanism are all directly placed into the cylinder after being installed outside the cylinder, which is convenient and fast to install. Materials that are often disassembled, such as end heads, can all use titanium alloy materials, making them light in weight and convenient to install. The loading and unloading fixture between the core and the rubber cylinder is inclined at a certain angle to facilitate the core to slide down by gravity. The inner wall of the model cylinder of the core holder is roughened to prevent cross-flow; the inner cavity is designed with a heat insulation and preservation device, the plug is designed with a piston compaction structure, each pressure measuring point and the plug are designed with a sand prevention structure, and a split-type heat preservation sleeve is used for independent heating and temperature control.

[0058] In some embodiments, a first one-way valve 19 is provided on the pipeline between the first flowmeter 18 and the first back pressure valve 20. The setting of the first one-way valve 19 avoids the test error of the first flowmeter 18 caused by gas backflow.

[0059] The gas-liquid metering system is arranged downstream of the model system and is used to meter the gas-liquid volume flowing out of the outlet end of the core holder 35. The gas-liquid metering system includes a gas-liquid separator 38. A second flowmeter 41 is arranged at the upper outlet end of the gas-liquid separator 38. A dryer 39 is arranged between the gas-liquid separator 38 and the second flowmeter 41. A graduated glass container 42 is arranged at the lower outlet end of the gas-liquid separator 38.

[0060] Specifically, when conducting a displacement simulation experiment, the gas-liquid metering system needs to be involved. The gas-liquid metering system is arranged downstream of the model system. The gas-liquid metering system includes a gas-liquid separator 38, a second flowmeter 41, and a glass container 42. Among them, the second flowmeter 41 is arranged on the upper outlet pipeline of the gas-liquid separator 38. A dryer 39 is arranged between the second flowmeter 41 and the gas-liquid separator 38. The glass container 42 is arranged at the lower outlet end of the gas-liquid separator 38, and the glass container 42 has graduations. The gas-liquid mixture flowing out of the outlet end of the model system is separated by the gas-liquid separator 38. The separated gas flows through the dryer 39 and then flows to the second flowmeter 41, and the second flowmeter 41 measures the amount of the gas. The separated liquid enters the glass container 42, and the volume of the liquid is read according to the graduations of the glass container 42. It can be understood that if the mass of the liquid needs to be measured, the method of weighing with a balance can be adopted.

[0061] In some embodiments, a fifth pressure gauge 43 and a fifth thermometer 44 are arranged on the upper inlet pipeline of the gas-liquid separator 38. The fifth pressure gauge 43 and the fifth thermometer 44 are used to measure the temperature and pressure of the gas-liquid mixture flowing into the gas-liquid separator 38 in real time.

[0062] In some embodiments, a second one-way valve 40 is arranged between the dryer 39 and the second flowmeter 41. The setting of the second one-way valve 40 avoids the measurement error of the second flowmeter 41 caused by gas backflow.

[0063] The temperature control system includes a first temperature control box 45 and a second temperature control box 46. The first temperature control box 45 is arranged outside the liquid injection system, the model system, and the pressure control system. The second temperature control box 46 is arranged outside the gas-liquid metering system. The first temperature control box 45 is used to simulate the formation temperature, and the second temperature control box 46 is used to simulate the surface temperature. The first temperature control box 45 and the second temperature control box 46 use hot air circulation and adopt PID regulation temperature control technology. The temperature inside the box is uniform, and the temperature control accuracy is high.

[0064] The vacuum pumping device is arranged on the branch pipeline of the inlet pipeline of the model system and is used to pump vacuum for the whole system. In some embodiments, the vacuum pumping device is a vacuum pump.

[0065] New type of CO 2 The miscibility pressure test and displacement method with crude oil. Using the new type of CO of the present invention 2Miscible pressure testing and displacement system with crude oil, including miscible pressure testing and displacement process.

[0066] The following takes the miscible pressure testing and displacement simulation experiment of CO 2 as an example to illustrate the method of the present invention. Among them, the miscible pressure testing includes the following steps:

[0067] (1) Check the airtightness of the system pipeline, adjust the first temperature control box 45 and the second temperature control box 46 to the target temperature, set the first back pressure valve 20 and the second back pressure valve 21 to the target pressure, and then use a vacuum pump to evacuate the system;

[0068] (2) Pump the crude oil placed in the second piston container 9 and the agent for reducing the miscible pressure in the third piston container 10 into the fourth piston container 11 according to a certain ratio, stir evenly and then pump it into the observation window 34;

[0069] (3) The CO 2 in the gas cylinder 1 is pressurized by the gas booster pump 2 and then flows through the pressure regulating valve 17, the first flowmeter 18 and the first one-way valve 19 in sequence, and then enters the observation window 34 through the first back pressure valve 20. Observe the miscible process and record the pressure when miscibility is achieved.

[0070] (4) After the experiment, clean the system with the water placed in the fifth piston container 8.

[0071] Among them, in step (3), if the CO 2 pressurized by the gas booster pump 2 is in a liquid state, inject the liquid CO 2 into the first piston container 7, and under the action of the first injection pump 12, pass the liquid CO 2 through the fourth valve 16 and the first back pressure valve 20 into the observation window 34. It can be understood that comparative experiments can be carried out by changing conditions such as experimental temperature, pressure, rock sample, agent, etc. to optimize experimental parameters.

[0072] The displacement simulation experiment includes the following steps:

[0073] (1) Check the airtightness of the system pipeline, install the rock sample in the core holder 35, adjust the first temperature control box 45 and the second temperature control box 46 to the target temperature, set the first back pressure valve 20 and the second back pressure valve 21 to the target pressure, and then use a vacuum pump to evacuate the system;

[0074] (2) Pump the crude oil in the second piston container 9 and the agent for reducing the miscible pressure in the third piston container 10 into the fourth piston container 11 according to a certain ratio, stir evenly and then inject it into the core holder 35 to saturate the core holder 35;

[0075] (3) The CO 2After being pressurized by the gas booster pump 2, it flows through the pressure regulating valve 17, the first flowmeter 18, and the first one-way valve 19 in sequence, and then is injected into the core holder 35 through the first back pressure valve 20 for displacement;

[0076] (4) Use the gas-liquid metering system to measure the gas-liquid volume at the outlet end of the core holder 35. Specifically, the gas-liquid mixture flowing out through the second back pressure valve 21 is separated into gas and liquid in the gas-liquid separator 38. The gas flows through the dryer 39 and the second one-way valve 40 in sequence and is then metered by the second flowmeter 41. The liquid enters the glass container 42, and the volume of the liquid is read through the scale of the glass container 42, and the displacement effect is analyzed;

[0077] (5) After the experiment is completed, clean the system with the water placed in the fifth piston container 8.

[0078] Among them, in step (3), if the CO 2 after being pressurized by the gas booster pump 2 is in a liquid state, then the liquid CO 2 is injected into the first piston container 7, and under the action of the first injection pump 12, the liquid CO 2 is introduced into the core holder 35 through the fourth valve 16 and the first back pressure valve 20.

[0079] Using the system of the present invention, the miscibility pressure test of oil, the agent for reducing the miscibility pressure and CO 2 can be carried out, that is, the corresponding miscibility pressure, temperature, types and concentrations of the agents for reducing the miscibility pressure and other conditions can be obtained.

[0080] When conducting the displacement simulation experiment of CO 2 , if a miscible displacement experiment is to be carried out, only need to adjust the temperature, pressure, types and concentrations of the agents for reducing the miscibility pressure during the displacement simulation experiment according to the corresponding miscibility conditions tested in the miscibility pressure test experiment, that is, adjust the pressure of the first back pressure valve 20 to be above the miscibility pressure of CO 2 , and at the same time set the temperature to be above the miscibility temperature, and adjust the types and concentrations of the agents for reducing the miscibility pressure. At this time, it can be ensured that the pressure value when CO 2 is injected into the core holder 35 is above the miscibility pressure, and CO 2 forms a miscible phase with the crude oil, and a miscible displacement experiment can be carried out. It can be understood that the system of the present invention can also carry out the miscibility pressure test of other gases, as well as the displacement simulation experiment of gases or liquids.

[0081] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms may be directed to different embodiments or examples. Moreover, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0082] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0083] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A novel CO 2 miscible pressure testing and displacement system with crude oil, It is characterized in that it includes: A gas injection system, which includes at least one gas cylinder. A gas booster pump is arranged on the outlet pipeline of the gas cylinder, a pressure regulating valve is arranged on the outlet pipeline of the gas booster pump, and a first flowmeter is arranged downstream of the pressure regulating valve; A liquid injection system, which includes a first piston container, a second piston container, a third piston container and a fourth piston container. The first piston container is arranged in parallel with the pressure regulating valve on the outlet pipeline of the gas booster pump. Crude oil and a chemical agent for reducing the miscibility pressure are respectively placed in the second piston container and the third piston container. The upper parts of the second piston container and the third piston container are both connected to the upper part of the fourth piston container, and a stirring device is arranged inside the fourth piston; A model system arranged downstream of the gas injection system and the liquid injection system, which includes an observation window and a core holder arranged in parallel. A differential pressure sensor is arranged on the pipeline between the inlet and outlet of the core holder; A pressure control system, which includes a back pressure control device and a manual pump. The pressure of the back pressure control device and the confining pressure of the core holder are controlled by the manual pump; A gas-liquid metering system, which is arranged downstream of the model system and is used to measure the gas-liquid volume flowing out of the outlet end of the core holder; A temperature control system, which includes a first temperature control box and a second temperature control box. The first temperature control box is arranged outside the liquid injection system, the model system and the pressure control system, and the second temperature control box is arranged outside the gas-liquid metering system; A vacuum pumping device, which is arranged on a branch of the inlet pipeline of the model system.

2. The system according to claim 1, it is characterized in that The lower parts of the first piston container, the second piston container, the third piston container and the fourth piston container are all connected to an injection pump.

3. The system according to claim 1, it is characterized in that The liquid injection system further includes a fifth piston container with water placed inside, and the fifth piston container is arranged in parallel with the second piston container.

4. The system according to claim 1, it is characterized in that The back pressure control device includes a first back pressure valve and a second back pressure valve. The first back pressure valve is arranged at the inlet end of the model system, and the second back pressure valve is arranged at the outlet end of the model system.

5. The system according to claim 4, it is characterized in that A first one-way valve is arranged on the pipeline between the first flowmeter and the first back pressure valve.

6. The system according to claim 5, it is characterized in that The output end of the manual pump is connected to a buffer tank. A first valve is arranged on the pipeline between the outlet end of the buffer tank and the first back pressure valve, a second valve is arranged on the pipeline between the outlet end of the buffer tank and the second back pressure valve, and a third valve is arranged on the pipeline between the outlet end of the buffer tank and the core holder.

7. The system according to claim 6, it is characterized in that The gas-liquid metering system includes a gas-liquid separator. A second flowmeter is provided at the upper outlet end of the gas-liquid separator. A dryer is provided between the gas-liquid separator and the second flowmeter. A graduated glass container is provided at the lower outlet end of the gas-liquid separator.

8. The system according to claim 7, wherein, a second one-way valve is provided between the dryer and the second flowmeter.

9. The system according to claim 7, wherein, pressure gauges and thermometers are provided at the upper part of the first piston container, the inlet and outlet ends of the model system, the outlet end of the buffer tank, and the inlet end of the gas-liquid separator.

10. A new type of CO 2 miscible pressure test and displacement method with crude oil wherein, using the system according to any one of claims 6-9, including a miscible pressure test and a displacement process, wherein, the miscible pressure test includes the following steps: (1) Check the airtightness of the system pipeline, adjust the first temperature control box and the second temperature control box to the target temperature, set the first back pressure valve and the second back pressure valve to the target pressure, and then use a vacuum pumping device to evacuate the system. The vacuum pumping device is a vacuum pump; (2) Pump the crude oil and the agent for reducing the miscible pressure placed in the second piston container and the third piston container into the fourth piston container according to a certain ratio, stir evenly and then pump them into the observation window; (3) CO in the gas cylinder 2 After being pressurized by a gas booster pump, it flows through a pressure regulating valve, a first flowmeter, and a first one-way valve in sequence, and then enters the observation window through a first backpressure valve to observe the miscible process and record the pressure at the time of achieving miscibility. The displacement process includes the following steps: (1) Check the airtightness of the system pipeline, install the rock sample in the core holder, adjust the first temperature control box and the second temperature control box to the target temperature, set the first back pressure valve and the second back pressure valve to the target pressure, and then use a vacuum pump to evacuate the system; (2) Pump the crude oil in the second piston container and the agent for reducing the miscible pressure in the third piston container into the fourth piston container according to a certain ratio, stir evenly and then inject them into the core holder to saturate the core holder; (3) The CO in the gas cylinder 2 is pressurized by a gas booster pump and then flows through a pressure regulating valve, a first flowmeter, and a first one-way valve in sequence, and is injected into the core holder through a first back pressure valve for displacement; (4) Use the gas-liquid metering system to measure the gas-liquid volume at the outlet end of the core holder, and analyze the displacement effect and its influencing factors.

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