Experimental device and method for enhancing carbonized water-thickened oil multiple contact through nano-silicon dioxide

Abstract

The invention relates to a nanosilicon dioxide enhanced carbonized water-thickened oil multi-contact experiment device and method, and belongs to the technical field of thickened oil reservoir exploitation. The nanosilicon dioxide enhanced carbonized water-thickened oil multi-contact experiment device comprises a fluid preparation system, a multi-contact experiment system, a test analysis system and a temperature control system; the fluid preparation system is used for preparing fluid for multiple contact experiments and comprises the steps of preparing nano SiO2 enhanced carbonized water and preparing formation oil; the multi-contact experiment system is used for controlling the nano SiO2 to enhance multi-contact of carbonized water and formation oil; the test analysis system is used for testing the properties of the nano SiO2 enhanced carbonized water and the high-pressure physical properties of the thickened oil after multiple contact processes; and the temperature control system is used for providing temperatures required by multiple contact experiments. The device can simulate the dissolution mass transfer of CO2 in the carbonized water-thickened oil multi-contact process under the action of nano SiO2 particles.

Description

Technical Field

[0001] The invention belongs to the technical field of heavy oil reservoir exploitation, and in particular relates to a nano-silicon dioxide enhanced carbonated water-heavy oil multiple contact experimental device and method. Background Art

[0002] Water flooding is one of the most commonly used oil recovery methods in oil fields, but high-viscosity heavy oil is prone to viscous fingering during water flooding, resulting in low oil recovery efficiency. 2 Flooding has the advantages of reducing viscosity, increasing production and reducing emissions, but due to gravity overburden, a gas channel is formed at the top, and the sweep coefficient is low. Carbonated water (i.e., CO dissolved in the water phase) 2 ) flooding combined with CO 2 The advantages of flooding and water flooding methods not only alleviate viscous fingering and gravity overburden, but also improve oil recovery efficiency, and the development effect is better than water flooding and CO 2 When carbonated water is injected into the reservoir to displace heavy oil, there are multiple contact processes between carbonated water and heavy oil. 2 The mass transfer from carbonized water to heavy oil reduces the viscosity of heavy oil, expands the volume of heavy oil, and reduces the oil-water interfacial tension. 2 The solubility in carbonated water is low, and the above effects need to be further improved.

[0003] In recent years, with the widespread application of nanotechnology in the field of oil and gas field development, it has attracted the attention of experts at home and abroad. 2 Enhanced carbonated water is a kind of water that uses nano-SiO 2 A new type of injection fluid formed by dispersing particles in carbonated water. Compared with traditional carbonated water, nano-SiO 2 Carbonated water can significantly increase CO 2 Solubility in water, strengthening CO 2 The mass transfer effect between carbonized water and heavy oil can improve the oil recovery rate and CO 2 Storage capacity. 2 A lot of research has been done on the multiple contact process between carbonized water and heavy oil, but for nano-SiO 2 There are few studies on the process of multiple contact between carbonized water and heavy oil, lack of effective experimental equipment and methods, and the high pressure physical properties of heavy oil and nano-SiO 2 The changes in the properties of carbonized water are still unclear. 2 Enhanced carbonation of CO 2 Saturation, SiO 2 Effects of concentration and mineralization on nano-SiO 2 The effect of enhancing the multiple contact process between carbonated water and heavy oil is still unclear, which seriously restricts the research of nano-SiO 2 Enhanced Carbonated Water CO 2 Drive application. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a nano-silica-enhanced carbonated water-heavy oil multiple contact experimental device and method. This experimental device can be used to study the multiple contact process between nano-SiO 2 enhanced carbonated water and heavy oil under high temperature and high pressure conditions, reveal the high-pressure physical properties of heavy oil (density, viscosity, gas-oil ratio, CO 2 gas-oil ratio, volume expansion coefficient) and the properties of nano-SiO 2 enhanced carbonated water (gas-water ratio, CO 2 gas-water ratio) during the multiple contact process between nano-SiO 2 enhanced carbonated water and heavy oil, clarify the influence of CO 2 saturation, SiO 2 concentration, salinity, etc. on the multiple contact process between nano-SiO 2 enhanced carbonated water and heavy oil, and analyze the CO 2 mass transfer mechanism during the multiple contact process between nano-SiO 2 enhanced carbonated water and heavy oil.

[0005] The technical solution of the present invention is as follows: A nano-silica-enhanced carbonated water-heavy oil multiple contact experimental device, including a fluid preparation system, a multiple contact experimental system, a test and analysis system, and a temperature control system; The fluid preparation system is used to prepare the fluids for the multiple contact experiment, including preparing nano-SiO 2 enhanced carbonated water and formation oil; The multiple contact experimental system is used to control the multiple contact between nano-SiO 2 enhanced carbonated water and formation oil; The test and analysis system is used to test the properties of nano-SiO 2 enhanced carbonated water and the high-pressure physical properties of heavy oil after the multiple contact process; the properties of nano-SiO 2 enhanced carbonated water include gas-water ratio, CO 2 gas-water ratio, and the high-pressure physical properties of heavy oil include density, viscosity, gas-oil ratio, CO 2 gas-oil ratio, volume expansion coefficient; The temperature control system is used to provide the temperature required for the multiple contact experiment.

[0006] Preferably according to the present invention, the fluid preparation system includes a parallel-connected heavy oil container, CH 4 container, CO 2 container, nano-SiO 2 enhanced carbonated water container, CH 4 gas cylinder and CO 2 gas cylinder; heavy oil container, CH 4Container, CO 2 Container and nano-SiO 2 The tops of the enhanced carbonated water containers are all connected to pipelines through pressure gauges and valves, and the bottoms are all connected to high-precision plunger pumps through valves and pipelines, CH 4 Container and CO 2 The top of the container is connected to CH through a pressure gauge, a valve and a pipeline respectively 4 Gas cylinder and CO 2 Gas cylinders are connected.

[0007] Preferably according to the present invention, the multiple contact experiment system includes a multiple contact model, a multiple contact model stirring device and a stirring block 13; one end of the multiple contact model is connected to the top of the nano-SiO enhanced carbonated water container through a pressure gauge, a valve and a pipeline, and the other end is connected to a high-precision plunger pump through a pipeline and a valve; the fluid in the multiple contact model is controlled by the multiple contact model stirring device. 2 One end of the multiple contact model is connected to the top of the nano-SiO enhanced carbonated water container through a pressure gauge, a valve and a pipeline, and the other end is connected to a high-precision plunger pump through a pipeline and a valve; the fluid in the multiple contact model is controlled by the multiple contact model stirring device.

[0008] More preferably, the multiple contact model is a cylindrical container device wrapped with a heat preservation sleeve for realizing the contact between nano-SiO enhanced carbonated water and formation oil; one end of the multiple contact model stirring device is fixed on the multiple contact model, and the other end is connected to a motor, and the multiple contact model is driven to rotate by the rotation of the motor for stirring the nano-SiO enhanced carbonated water and formation oil inside the multiple contact model. 2 One end of the multiple contact model stirring device is fixed on the multiple contact model, and the other end is connected to a motor, and the multiple contact model is driven to rotate by the rotation of the motor for stirring the nano-SiO enhanced carbonated water and formation oil inside the multiple contact model. 2 Enhanced carbonated water and formation oil.

[0009] More preferably, a multiple contact model volume meter is further provided on the outer shell of the multiple contact model for visually displaying the volume change inside the multiple contact model.

[0010] More preferably, the rotation speed of the multiple contact model is 2 r / min.

[0011] More preferably, the total volume of the multiple contact model is greater than 400 ml.

[0012] Preferably according to the present invention, a stirring block is placed in the multiple contact model, the volume of the stirring block is greater than 50 ml, and the weight is not less than 200 g.

[0013] Preferably according to the present invention, the test analysis system includes a gas-liquid separator, a gas flowmeter, a falling ball viscometer, a gas component analyzer, an electronic balance, a hand pump, and several gas bags; the top of the gas-liquid separator is connected to the top valve of the multiple contact model through a backpressure valve and a pipeline, the lower part of the gas-liquid separator is an outlet with a valve, and directly below the outlet is a liquid collection container, which is moved onto the electronic balance for weighing to measure the liquid mass and calculate the gas-liquid ratio; there is also an outlet at the upper part of the gas-liquid separator, which is connected to the gas flowmeter, and the outlet end of the gas flowmeter is connected to a detachable and replaceable gas bag through a pipeline, and the separated gas is collected by the gas bag, and then the CH 4 and CO 2 volume percentages in the separated gas are detected by the gas component analyzer.

[0014] Preferably according to the present invention, the standard volume of the gas bag is not less than 500 ml, and the gas bag is evacuated before collecting the gas for gas collection and gas component detection.

[0015] Preferably according to the present invention, one end of the falling ball viscometer is connected to the top valve of the multiple contact model through a pressure gauge, and the other end is connected to a backpressure valve, which is used to control the pressure of the exported fluid to be maintained under experimental conditions, and the working conditions of the falling ball viscometer meet the requirements of normal operation at 50 °C and 18 MPa, and it is used to measure the viscosities of heavy oil before and after multiple contacts between nano-SiO 2 enhanced carbonated water and heavy oil under high temperature and high pressure conditions. High temperature and high pressure refer to: the value range of high temperature is 30 - 50 °C, and the value range of high pressure is 10 - 18 MPa.

[0016] Preferably according to the present invention, the temperature control system includes a multiple contact model, a gas-liquid separator, a falling ball viscometer, a nano-SiO 2 enhanced carbonated water container, and a heavy oil container. The pipelines connecting the multiple contact model, the gas-liquid separator, the falling ball viscometer, and the nano-SiO 2 enhanced carbonated water containers are wrapped with heating tapes on the outside for heating the above containers and the pipelines connecting the above containers.

[0017] Further, the heavy oil container, the CH 4 container, the CO 2 container, the nano-SiO 2 enhanced carbonated water container, and the top of the multiple contact model are all connected to a vacuum pump, and the heavy oil container, the CH 4 container, the CO 2 container, the nano-SiO 2 enhanced carbonated water container, and the multiple contact model are evacuated before the experiment.

[0018] The technical solution of the present invention also includes a method for multiple contact experiments between nano-silica enhanced carbonated water and heavy oil, which includes the following steps: (1)Prepare formation oil; measure the density of formation oil ; (2)Prepare nano-SiO 2 fluid; measure the density of nano-SiO 2 fluid, record it as and introduce the prepared nano-SiO 2 fluid into the nano-SiO 2 enhanced carbonated water container; (3)Prepare nano-SiO 2 enhanced carbonated water; introduce all the CO 2 in the CO 2 container into the nano-SiO 2 enhanced carbonated water container through a pipeline, and apply pressure to the nano-SiO 2 enhanced carbonated water container by a high-precision plunger pump to dissolve CO 2 into the nano-SiO 2 fluid until the experimental pressure remains unchanged, and obtain nano-SiO 2 enhanced carbonated water; (4)Conduct multiple contact experiments between nano-SiO 2 enhanced carbonated water and heavy oil; Before contact, introduce the prepared formation oil into a falling ball viscometer and measure the viscosity of the formation oil before contact μ 0 ; Then introduce the formation oil into a multiple contact model, and then introduce nano-SiO 2 enhanced carbonated water into the multiple contact model, record the volume of formation oil before the i-th contact V 0i and record the volume of formation oil after the i-th contact V 1i , calculate the volume expansion coefficient ; Keep the experimental pressure unchanged through a high-precision plunger pump during the process; Stir the fluid in the multiple contact model through the stirring device of the multiple contact model, control the pressure in the multiple contact model during the process until it stabilizes at the experimental pressure, stop stirring, and let it stand for a period of time until the oil and water are separated.

[0019] (5)Calculate the gas-water ratio of nano-SiO 2 enhanced carbonated water after contact; Export nano-SiO 2 enhanced carbonated water from the lower end of the multiple contact model to a gas-liquid separator, and record the initial reading of the gas flowmeter at the beginning V ai and the reading of the gas flowmeter after the separation process ends V bi, collect and separate the gas, and use a gas component analyzer to detect nano-SiO 2 Enhance the CO in the carbonated water separation gas 2 Volume percentage, denoted as , for calculating nano-SiO 2 CO after contact with enhanced carbonated water 2 Gas-water ratio; use an electronic balance to weigh the mass of nano-SiO after gas-liquid separation 2 Enhanced carbonated water and record it as m wi , drain all nano-SiO 2 Enhanced carbonated water until oil production; (6) Calculate the gas-oil ratio of the heavy oil after contact; Derive a part of the formation oil from the lower end of the multiple contact model into the gas-liquid separator. When the growth rate of the gas flowmeter is stable, close the valve at the lower end of the gas-liquid separator, and record the volume reading of the multiple contact model before starting to test the gas-oil ratio , close the valve of the multiple contact model after deriving a part of the formation oil, and record the volume reading of the multiple contact model after the formation oil is derived , and record the initial reading of the gas flowmeter at the same time V ci And the reading of the gas flowmeter after the separation process ends V di , use an electronic balance to weigh the mass of the formation oil after contact after separating the gas m oi , collect and separate the gas, and use a gas component analyzer to detect the CO in the separated gas of the formation oil after different contact times 2 Volume percentage, denoted as ; (7) Repeat steps (4) to (6) to complete the multiple contact experiment of nano-SiO 2 Enhanced carbonated water - heavy oil; calculate the gas-water ratio of nano-SiO 2 Enhanced carbonated water respectively under different contact times , gas-oil ratio of heavy oil , density of formation oil , volume expansion coefficient , nano-SiO 2 CO of enhanced carbonated water 2 Gas-water ratio , CO of heavy oil 2 Gas-oil ratio ; after the last contact, derive a part of the heavy oil from the lower end of the multiple contact model into the falling ball viscometer to measure the viscosity of the heavy oil after multiple contacts μ ; Analyze the variation law of the above parameters with the increase of contact times, and study nano-SiO 2Enhanced mass transfer during multiple contact between carbonated water and heavy oil reveals the role of nano-SiO 2 Enhanced carbonized water to improve heavy oil recovery mechanism; (8) Repeat steps (1) to (7) to change the nano-SiO 2 Enhanced carbonated water properties include mineralization, CO 2 Saturation, nano-SiO 2 Particle concentration and salt type, nano-SiO after changing properties 2 Enhanced multiple contact experiments between carbonated water and heavy oil to clarify the role of nano-SiO 2 Effect of enhanced carbonized water properties on nano-SiO 2 The influence of enhanced carbonized water on gas-water ratio and high-pressure physical properties of heavy oil.

[0020] According to the preferred embodiment of the present invention, the nano-SiO2 introduced into the multiple contact model each time 2 The volume ratio of enhanced carbonized water to formation oil in the multiple contact model is 1:1.

[0021] Preferably according to the present invention, the standing time is not less than 6 h, until the oil and water are separated into separate layers.

[0022] According to the preferred embodiment of the present invention, the volume expansion coefficient of the heavy oil after each contact is calculated according to formula (I): : ; In formula (I), is the volume expansion coefficient of the formation oil after the ith contact, dimensionless; V 1i For the i After contact, all nano-SiO 2 Enhanced formation oil volume after carbonation of water; V 0i For the i Secondary contact with nano-SiO 2 Enhanced formation oil volume before carbonation of water.

[0023] According to the preferred embodiment of the present invention, the nano-SiO2 after contact at different contact times is calculated by formula (II). 2 Increase the gas-water ratio of carbonated water ; ; In formula (II), For the i After contact with nano-SiO 2 Gas-water ratio of enhanced carbonated water, ml / ml; V bi is the flow meter reading after the gas-liquid separation process is completed, ml; Vai is the initial reading of the flowmeter at the start of gas-liquid separation, ml; m wi is the i mass of nano-SiO 2 enhanced carbonated water collected by the separator after the th contact, g; 2 is the density of nano-SiO 3 enhanced carbonated water, g / cm ; 2 The CO 2 gas-water ratio of nano-SiO enhanced carbonated water after contact is calculated according to formula (Ⅲ); ; In formula (Ⅲ), is the i th contact, and 2 the volume percentage of CO 2 in the separated gas of nano-SiO enhanced carbonated water is dimensionless; i is the 2 CO 2 gas-water ratio of nano-SiO

[0024] enhanced carbonated water after contact, ml / ml. According to the preference of the present invention, the volume of formation oil exported per contact is 15 - 25 ml; The gas-oil ratio of heavy oil after each contact is calculated by the following formula (Ⅳ); ; In formula (Ⅳ), is the i th contact, and V ci is the initial reading of the flowmeter at the start of gas-liquid separation, ml; V di is the reading of the flowmeter after the end of the gas-liquid separation process, ml; m oi is the i mass of formation oil collected during the gas-liquid separation process after the th contact, g; 3 is the density of degassed formation oil, g / cm ; The density of formation oil after each contact is calculated according to formula (Ⅴ): ; In formula (Ⅴ), is the density of formation oil after the i-th contact, g / cm 3 ; Before the start of the first contact test for the gas-oil ratio, the volume readings of the multiple-contact model are taken, in ml; i Before the start of the first contact test for the gas-oil ratio, the volume readings of the multiple-contact model are taken, in ml; After the i th contact, after the formation oil is exported, the volume readings of the multiple-contact model are taken, in ml; According to formula (VI), calculate the CO 2 gas-oil ratio : ; In formula (VI), After the i th contact, the CO 2 gas-oil ratio of the heavy oil, in ml / ml; After the i th contact, the volume percentage of CO 2 in the separated gas of the heavy oil, dimensionless.

[0025] The beneficial effects of the present invention are as follows: 1. The nano-SiO 2 enhanced carbonated water-heavy oil multiple-contact experimental device proposed by the present invention can realize the multiple-contact process between heavy oil and nano-SiO 2 enhanced carbonated water, and can simulate the dissolution mass transfer of CO 2 under the action of nano-SiO 2 particles during the multiple-contact process of carbonated water-heavy oil.

[0026] 2. The nano-SiO 2 enhanced carbonated water-heavy oil multiple-contact experimental method proposed by the present invention can reveal the high-pressure physical properties of heavy oil (density, viscosity, gas-oil ratio, CO 2 gas-oil ratio, volume expansion coefficient) and the properties of nano-SiO 2 enhanced carbonated water (gas-water ratio, CO 2 gas-water ratio) during the multiple-contact process between nano-SiO 2 enhanced carbonated water and heavy oil, clarify the influence of CO 2 saturation, SiO 2 concentration, salinity, etc. on the multiple-contact process between nano-SiO 2 enhanced carbonated water and heavy oil, analyze the CO 2 mass transfer mechanism during the multiple-contact process of nano-SiO 2 enhanced carbonated water-heavy oil, which is helpful for the application of nano-SiO 2 enhanced carbonated water CO 2 flooding technology in oilfields. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 FIG. is a schematic structural diagram of the nano-silica enhanced carbonated water-heavy oil multiple-contact experimental device in Example 2.

[0028] Among them, 1. High-precision plunger pump, 2. CH 4 Container, 3. Heavy oil container, 4. CO 2 Container, 5. Nano-SiO 2 Enhanced carbonated water container, 6. CO 2 Gas cylinder, 7. CH 4 Gas cylinder, 8. Thermal insulation sleeve, 9. Valve, 10. Pressure gauge, 11. Multi-contact model stirring device, 12. Multi-contact model volume meter, 13. Stirring block, 14. Multi-contact model, 15. Back pressure valve, 16. Gas-liquid separator, 17. Liquid collection container, 18. Electronic balance, 19. Gas flow meter, 20. Gas bag, 21. Hand pump, 22. Falling ball viscometer, 23. Vacuum pump, 24. Gas component analyzer.

[0029] Figure 2 For the nano-SiO in the experimental method of the present invention 2 Graph of the gas-water ratio of enhanced carbonated water varying with the number of contacts.

[0030] Figure 3 Graph of the oil-gas ratio of formation oil varying with the number of contacts in the experimental method of the present invention.

[0031] Figure 4 For the nano-SiO in the experimental method of the present invention 2 Enhanced carbonated water CO 2 Graph of the gas-water ratio varying with the number of contacts.

[0032] Figure 5 For the formation oil CO in the experimental method of the present invention 2 Graph of the gas-oil ratio varying with the number of contacts.

[0033] Figure 6 Graph of the volume expansion coefficient of formation oil varying with the number of contacts in the experimental method of the present invention.

[0034] Figure 7 Graph of the density of formation oil varying with the number of contacts in the experimental method of the present invention. Specific implementation mode

[0035] The technical solution of the present invention will be described in detail below in conjunction with the drawings and embodiments.

[0036] Embodiment 1 The nano-silica enhanced carbonated water-heavy oil multi-contact experimental device includes a fluid preparation system, a multi-contact experimental system, a test analysis system, and a temperature control system; The fluid preparation system is used to prepare the fluids for the multi-contact experiment, including preparing nano-SiO 2 Enhanced carbonated water and preparing formation oil; The multiple-contact experiment system is used to control nano-SiO 2 to enhance the multiple contact of carbonated water and formation oil; The test and analysis system is used to test the properties of nano-SiO after the multiple-contact process 2 to enhance the properties of carbonated water and the high-pressure properties of heavy oil; nano-SiO 2 The properties of enhanced carbonated water include gas-water ratio, CO 2 The gas-water ratio, and the high-pressure properties of heavy oil include density, viscosity, gas-oil ratio, CO 2 gas-oil ratio, and volume expansion coefficient; The temperature control system is used to provide the temperature required for the multiple-contact experiment.

[0037] Example 2 The nano-silica enhanced carbonated water-heavy oil multiple-contact experimental device according to Example 1, as Figure 1 shown, is characterized in that: The fluid preparation system includes a parallel-connected heavy oil container 3, CH 4 container 2, CO 2 container 4, nano-SiO 2 enhanced carbonated water container 5, CH 4 gas cylinder 7 and CO 2 gas cylinder 6; the tops of the heavy oil container 3, CH 4 container 2, CO 2 container 4 and nano-SiO 2 enhanced carbonated water container 5 are all connected to the pipeline through a pressure gauge 10 and a valve 9, and the bottoms are all connected to the high-precision piston pump 1 through a valve 9 and a pipeline. CH 4 container 2 and CO 2 The tops of container 4 are respectively connected to CH 4 gas cylinder 7 and CO 2 gas cylinder 6 through a pressure gauge 10, a valve 9 and a pipeline.

[0038] The multiple-contact experiment system includes a multiple-contact model 14, a multiple-contact model stirring device 11 and a stirring block 13; one end of the multiple-contact model 14 is connected to the top of the nano-SiO 2 enhanced carbonated water container 5 through a pressure gauge 10, a valve 9 and a pipeline, and the other end is connected to the high-precision piston pump 1 through a pipeline and a valve 9; the fluid in the multiple-contact model 14 is controlled by the multiple-contact model stirring device 11.

[0039] The multiple-contact model 14 is a cylindrical container device wrapped with a heat-insulating sleeve 8, which is used to realize nano-SiO 2Enhance the contact between carbonated water and formation oil; One end of the multiple-contact model stirring device 11 is fixed on the multiple-contact model 14, and the other end is connected to a motor. The motor rotates to drive the multiple-contact model 14 to rotate, which is used to stir the nano-SiO inside the multiple-contact model 14 2 Enhance the carbonated water and formation oil.

[0040] A multiple-contact model volume meter 12 is also provided on the outer shell of the multiple-contact model 14, which is used to intuitively display the volume change inside the multiple-contact model 14. The rotation speed of the multiple-contact model 14 is 2 r / min. The total volume of the multiple-contact model 14 is greater than 400 ml. It is necessary to ensure that enough viscous oil can be exported for property analysis after each contact.

[0041] A stirring block 13 is placed in the multiple-contact model 14. The volume of the stirring block 13 is greater than 50 ml and the weight is not less than 200 g. This is to strengthen the stirring effect and improve the contact efficiency between the viscous oil and nano-SiO 2 Enhance the contact efficiency of carbonated water.

[0042] The test and analysis system includes a gas-liquid separator 16, a gas flow meter 19, a falling-ball viscometer 22, a gas component analyzer 24, an electronic balance 18, a hand pump 21 and several gas bags 20; The top of the gas-liquid separator 16 is connected to the top valve 9 of the multiple-contact model 14 through a back-pressure valve 15 and a pipeline. The lower part of the gas-liquid separator 16 is an outlet with a valve 9, and directly below the outlet is a liquid collection container 17. The liquid collection container 17 is moved onto the electronic balance 18 for weighing to measure the liquid mass and calculate the gas-liquid ratio; There is also an outlet at the upper part of the gas-liquid separator 16, which is connected to the gas flow meter 19. The outlet end of the gas flow meter 19 is connected to the detachable and replaceable gas bag 20 through a pipeline. The separated gas is collected through the gas bag 20, and then the CH in the separated gas is detected by the gas component analyzer 24 4 and CO 2 Volume percentage.

[0043] The standard volume of the gas bag 20 is not less than 500 ml to reduce the component detection error. The gas bag 20 is evacuated before collecting the gas, which is used for gas collection and gas component detection.

[0044] One end of the falling-ball viscometer 22 is connected to the top valve 9 of the multiple-contact model 14 through a pressure gauge 10, and the other end is connected to the back-pressure valve 15, which is used to control the pressure of the exported fluid to remain under experimental conditions. And the working conditions of the falling-ball viscometer 22 meet the requirements of normal operation at 50 °C and 18 MPa, which is used to measure the viscosity of the viscous oil before and after multiple contacts between nano-SiO 2 Enhance the carbonated water-viscous oil multiple contacts before and after the viscosity of the viscous oil.

[0045] The temperature control system includes the multiple-contact model 14, the gas-liquid separator 16, the falling-ball viscometer 22, nano-SiO2 Enhanced carbonated water container 5 and viscous oil container 3, connecting the multiple contact model 14, gas-liquid separator 16, falling ball viscometer 22, nano-SiO 2 The outer side of the pipeline connecting the enhanced carbonated water container 5 is wrapped with a heating tape for heating the above containers and the pipelines connecting the above containers.

[0046] The pipeline should meet the requirements for use under high temperature and high pressure. Multiple heating tapes connected to a temperature controller are used to wrap all the pipelines through which the experimental fluid passes and is exposed to the air, so that the experimental fluid is always under experimental conditions, maintaining good fluidity and preventing the premature precipitation of dissolved gases.

[0047] Viscous oil container 3, CH 4 Container 2, CO 2 Container 4, nano-SiO 2 The enhanced carbonated water container 5 and the top of the multiple contact model 14 are both connected to a vacuum pump 23. Before the experiment, the viscous oil container 3, CH 4 Container 2, CO 2 Container 4, nano-SiO 2 Enhanced carbonated water container 5 and the multiple contact model 14 are evacuated.

[0048] Example 3 The nano-silica enhanced carbonated water-viscous oil multiple contact experimental device according to Example 2 is characterized in that: The total volume of the multiple contact model 14 is 450 ml. The volume of the stirring block 13 is 83 ml and the mass is 314 g. The standard volume of the air bag 20 is 500 ml. The temperature upper limit of the falling ball viscometer 22 is 120 °C and the pressure upper limit is 45.0 MPa.

[0049] Example 4 The nano-silica enhanced carbonated water-viscous oil multiple contact experimental method is realized by the nano-silica enhanced carbonated water-viscous oil multiple contact experimental device described in Example 3, and includes the following steps: (1) Prepare formation oil; prepare degassed formation oil, measure the density of the degassed formation oil, and record it as ; Import the degassed formation oil into the viscous oil container 3, and prepare CH in the CH 4 container 2 according to the gas-oil ratio of the formation oil dissolved gas and the gas compression factor, and import the CH 4 into the viscous oil container 3, and control it under the formation pressure and temperature conditions until the CH 4 is fully dissolved and the pressure in the viscous oil container 3 is stable to obtain formation oil, and measure the density of the formation oil 4 ; In this example, the density of the degassed formation oil ; In this example, the density of the degassed formation oil = 0.9803 g / cm 3; Formation temperature is 40°C, pressure is 12.0 MPa; formation oil density = 0.9412 g / cm 3 ; (2) Preparation of nano-SiO 2 fluid; successively add sodium chloride, polyvinylpyrrolidone, and nano-SiO 2 particles into distilled water, stir with a glass rod, transfer the stirred fluid to an ultrasonic disperser for dispersion to obtain a uniformly dispersed nano-SiO 2 fluid, measure the density of the nano-SiO 2 fluid, and record it as , and introduce the prepared nano-SiO 2 fluid into the nano-SiO 2 enhanced carbonated water container 5; The frequency of the ultrasonic disperser is not less than 25 kHz, the number of dispersions is not less than 3 times, and the dispersion time for each time is 15 to 20 minutes. Avoid temperature changes due to too long dispersion time to achieve a better dispersion effect and avoid precipitation of nano-SiO 2 particles. In this embodiment, the concentration of nano-SiO 2 is 0.1 wt%, the concentration of polyvinylpyrrolidone is 1 wt%, the NaCl concentration is 0.5 wt%, and the density of the nano-SiO 2 fluid = 1.0162 g / cm 3 .

[0050] The frequency of the ultrasonic disperser is not less than 25 kHz, the number of dispersions is not less than 3 times, and the dispersion time for each time is 15 to 20 minutes. Avoid temperature changes due to too long dispersion time to achieve a better dispersion effect and avoid precipitation of nano-SiO 2 particles. In this embodiment, the frequency of the ultrasonic disperser is 25 kHz, the number of dispersions is 3 times, and the dispersion time for each time is 15 minutes.

[0051] (3) Preparation of nano-SiO 2 enhanced carbonated water; introduce all the CO 2 in container 4 into the nano-SiO 2 enhanced carbonated water container 5 through a pipeline, and apply pressure to the nano-SiO 2 enhanced carbonated water container 5 by the high-precision plunger pump 1 to dissolve CO 2 into the nano-SiO 2 fluid until the experimental pressure remains unchanged to obtain nano-SiO 2 enhanced carbonated water; each time of nano-SiO 2 enhanced carbonated water - heavy oil contact requires the preparation of nano-SiO 2 enhanced carbonated water 2Enhanced carbonated water to avoid precipitation of nano-SiO 2 particles with the increase in the number of contacts. In this embodiment, the gas-water ratio of the enhanced carbonated water is 29.6 ml / ml. 2 Nano-SiO 2 in the enhanced carbonated water 2 Particles precipitate. In this embodiment, the gas-water ratio of the enhanced carbonated water is 29.6 ml / ml. 2 Enhanced carbonated water gas-water ratio is 29.6 ml / ml.

[0052] (4) Conduct experiments on multiple contacts between the enhanced carbonated water with nano-SiO 2 and heavy oil; 2 Before contact, introduce the prepared formation oil into the falling ball viscometer 22 to measure the viscosity of the formation oil before contact; Before contact, introduce the prepared formation oil into the falling ball viscometer 22 to measure the viscosity of the formation oil before contact μ 0 ; Then introduce the formation oil into the multiple contact model 14, and then introduce the enhanced carbonated water with nano-SiO 2 into the multiple contact model 14, record the volume of the formation oil before the i-th contact 2 Enhanced carbonated water, record the volume of the formation oil before the i-th contact V 0i , record the volume of the formation oil after the i-th contact V 1i , calculate the volume expansion coefficient ; Keep the experimental pressure constant through the high-precision plunger pump 1 during the process; Stir the fluid in the multiple contact model 14 through the multiple contact model stirring device 11. Control the pressure in the multiple contact model 14 during the process until it stabilizes at the experimental pressure, stop stirring, and let it stand for a period of time until the oil and water are separated. In this embodiment, i i = 1, the viscosity of the formation oil before contact μ 0 = 3561.9 mPa . s, the volume of the formation oil before the first contact V 0i = 200 ml, the volume of the formation oil after the first contact V 1i = 220.006 ml.

[0053] The volume ratio of the enhanced carbonated water with nano-SiO 2 introduced into the multiple contact model 14 each time to the volume of the formation oil in the multiple contact model 14 is 1:1. In this embodiment, the volume of the heavy oil before the first contact is 200 ml. Therefore, the volume of the enhanced carbonated water with nano-SiO 2 introduced into the multiple contact model 14 2 Enhanced carbonated water volume and the volume ratio of the formation oil in the multiple contact model 14 is 1:1. In this embodiment, the volume of the heavy oil before the first contact is 200 ml. Therefore, the volume of the enhanced carbonated water with nano-SiO 2 introduced into the multiple contact model 14 2 Enhanced carbonated water volume is 200 ml.

[0054] The standing time is not less than 6 h until the oil and water are separated. The standing time is 8 h.

[0055] Calculate the volume expansion coefficient of the heavy oil after each contact according to formula (Ⅰ) : ; In formula (I), is the formation oil volume expansion coefficient after the i-th contact, dimensionless; V 1i is the i -th time after contact, the total volume of formation oil after all nano-SiO 2 enhanced carbonated water is exported; V 0i is the i -th time before contacting nano-SiO 2 enhanced carbonated water. In this embodiment, i = 1; V 1i = 220.006 ml; V 0i = 200 ml; = 1.11.

[0056] (5) Calculate the gas-water ratio of nano-SiO 2 enhanced carbonated water after contact; Export nano-SiO 2 enhanced carbonated water from the lower end of the multiple contact model 14 to the gas-liquid separator 16, and record the initial reading V ai of the gas flowmeter 19 at the beginning and the reading V bi of the gas flowmeter 19 after the separation process ends 2 , collect the separated gas, and use the gas component analyzer 24 to detect the CO 2 volume percentage in the separated gas of nano-SiO enhanced carbonated water, denoted as 2 , for calculating the CO 2 gas-water ratio after contact with nano-SiO 2 enhanced carbonated water; use the electronic balance 18 to weigh the mass of nano-SiO m wi enhanced carbonated water after gas-liquid separation and record it as 2 , drain all nano-SiO i enhanced carbonated water in the multiple contact model 14 until oil production; in this embodiment, V ai = 1; the initial reading of the gas flowmeter 19 V bi = 176 ml, the reading of the gas flowmeter 19 after the separation process ends 2 = 832 ml, the CO 2 volume percentage m wi = 48.667 g.

[0057] ​The contact times of nano-SiO2 were calculated by formula (II). 2 Increase the gas-water ratio of carbonated water ; ; In formula (II), For the i After contact with nano-SiO 2 Gas-water ratio of enhanced carbonated water, ml / ml; V bi is the flow meter reading after the gas-liquid separation process is completed, ml; V ai is the initial reading of the flow meter at the beginning of gas-liquid separation, ml; m wi For the i Nano-SiO collected by the separator after the first contact 2 Enhance the quality of carbonated water, g; Nano-SiO 2 Enhanced density of carbonated water g / cm 3 In this embodiment, i =1; V bi =832ml; V ai =176ml; m wi =48.667g; =1.0162g / cm 3 , calculated =13.70ml / ml.

[0058] According to formula (III), the contact nano-SiO 2 Enhanced CO of carbonated water 2 Gas-water ratio ; ; In formula (III), For the i After contact with nano-SiO 2 Enhanced Carbonation of Water to Separate CO from Gas 2 Volume percentage, dimensionless; For the i After contact with nano-SiO 2 Enhanced CO of carbonated water 2 Gas-water ratio, ml / ml. In this embodiment, i =1; =0.3482; calculated =4.77ml / ml.

[0059] (6) Calculate the gas-oil ratio of the heavy oil after contact; Drain a portion of the formation oil from the lower end of the multiple-contact model 14 into the gas-liquid separator 16. Wait until the growth rate of the gas flowmeter 19 stabilizes, then close the valve 9 at the lower end of the gas-liquid separator 16, and record the volume reading of the multiple-contact model 14 before starting the measurement of the gas-oil ratio. After draining a portion of the formation oil, close the valve 9 of the multiple-contact model 14, and record the volume reading of the multiple-contact model 14 after the formation oil is drained. At the same time, record the initial reading of the gas flowmeter 19. V ci And the reading of the gas flowmeter 19 after the separation process ends. V di Weigh the post-contact formation oil after gas separation using the electronic balance 18. m oi Collect the separated gas, and use the gas component analyzer 24 to detect the volume percentage of CO in the separated gas of the formation oil after different contact times, denoted as 2 ; In this embodiment, = 1; i = 214.343 ml, = 189.08 ml, the initial reading of the gas flowmeter 19 = 1264 ml, the reading of the gas flowmeter 19 after the separation process ends V ci = 1768 ml, the mass of the formation oil V di = 21.335 g, the volume percentage of CO m oi = 56.95%. 2 Volume percentage = 56.95%.

[0060] The volume of the formation oil drained each time is 15 - 25 ml; control the volume of the drained oil to avoid too small a volume of the drained oil, which may lead to a large error in calculating the gas-oil ratio, and at the same time avoid too large a volume of the drained oil, which may result in fewer contact times. In this embodiment, the volume of the formation oil drained each time is 20 ml.

[0061] Calculate the gas-oil ratio of the heavy oil after each contact through the following formula (IV) ; ; In formula (IV), is the gas-oil ratio of the heavy oil after the i -th contact, ml / ml; V ci is the initial reading of the flowmeter at the start of gas-liquid separation, ml; V di is the reading of the flowmeter after the gas-liquid separation process ends, ml;m oi is the mass of the formation oil collected during the i th gas-liquid separation contact, g; is the density of the degassed formation oil, g / cm 3 ; In this embodiment, i = 1; V ci = 1264 ml; V di = 1768 ml; m oi = 21.335 g; = 0.9803 g / cm 3 , and = 23.158 ml / ml is calculated.

[0062] Calculate the density of the formation oil after each contact according to formula (V) :

[0063] In formula (V), is the density of the formation oil after the 3 th contact, g / cm is the i volume reading of the multiple contact model 14 before testing the gas-oil ratio at the start of the th contact, ml; i is the i volume reading of the multiple contact model 14 after the th contact after the formation oil is drained; In this embodiment, = 1; = 214.343 ml; = 189.08 ml;

[0064] Calculate the CO 2 gas-oil ratio of the heavy oil after contact according to formula (VI) :

[0065] In formula (VI), i is the CO 2 gas-oil ratio of the heavy oil after the i th contact, ml / ml; is the 2 volume percentage of CO in the separated gas of the heavy oil after the th contact, dimensionless. In this embodiment,

[0066]

[0066] In steps (5) and (6), a hand pump is used to control the pressure of the back-pressure valve 15, cooperating with the high-precision plunger pump 1, to ensure that the contact with the heavy oil each time is maintained at the experimental pressure, avoiding calculation errors caused by the pressure drop due to the export of the fluid in the inner cavity of the model 14 during multiple contacts. In this embodiment, the pressure of multiple contacts with the model 14 is controlled at 12.0 MPa, and the pressure range of the hand pump is 10 - 12 MPa.

[0067] (7) Repeat steps (4) - (6) to complete the multiple-contact experiment of nano-SiO 2 enhanced carbonated water - heavy oil; calculate the gas-water ratio of nano-SiO 2 enhanced carbonated water, the gas-oil ratio of heavy oil , the density of formation oil , the volume expansion coefficient , nano-SiO enhanced carbonated water CO 2 gas-water ratio 2 , the CO gas-oil ratio of heavy oil 2 , the CO gas-oil ratio; after the last contact, export part of the heavy oil from the lower end of the multiple-contact model 14 to the falling-ball viscometer 22 to measure the viscosity of the heavy oil after multiple contacts μ ; Analyze the variation law of the above parameters with the increase of the contact times, study the mass transfer effect during the multiple-contact process of nano-SiO 2 enhanced carbonated water - heavy oil, and reveal the mechanism of nano-SiO 2 enhanced carbonated water to improve the heavy oil recovery rate; in this embodiment, the viscosity of the heavy oil after multiple contacts μ = 1883.1 mPa·s, and the calculation results during the multiple-contact process are as Figures 2 to 7 shown.

[0068] As Figures 2 to 7 shown, during the multiple-contact process of nano-SiO 2 enhanced carbonated water - heavy oil, with the increase of the contact times, the gas-oil ratio of the heavy oil gradually increases, and the CO 2 gas-oil ratio of the heavy oil also gradually increases, and the increasing amplitude of the CO 2 gas-oil ratio gradually decreases, while the gas-water ratio of nano-SiO 2 enhanced carbonated water and the CO 2 gas-water ratio decrease significantly after the first contact, and the gas-water ratio gradually increases during the multiple-contact process, but is still lower than the initial gas-water ratio, indicating that CO 2 mass transfers from nano-SiO 2 enhanced carbonated water to the heavy oil. At the beginning of the contact, the gas-oil ratio of the heavy oil is relatively low, and the gas-water ratio of nano-SiO 2 enhanced carbonated water is relatively high, and CO2 From nano-SiO 2 The mass transfer rate from the nano-SiO enhanced carbonated water to the heavy oil is fast. During multiple contact processes, the gas-oil ratio of the heavy oil increases, and the CO 2 mass transfer effect slows down; as the number of contacts increases, the volume expansion coefficient of the heavy oil increases, and the density and viscosity of the heavy oil decrease, indicating that CO 2 From nano-SiO 2 The mass transfer from the nano-SiO enhanced carbonated water to the heavy oil improves the high-pressure physical properties of the heavy oil. However, during multiple contact processes, the CO 2 mass transfer effect becomes slower, and the improvement amplitude of the high-pressure physical properties of the heavy oil gradually decreases.

[0069] (8) Repeat steps (1) to (7), changing the properties of the nano-SiO 2 enhanced carbonated water, including salinity, CO 2 saturation, nano-SiO 2 particle concentration, and salt type. Conduct multiple contact experiments between the nano-SiO 2 enhanced carbonated water with changed properties and the heavy oil to clarify the influence of the property parameters of the nano-SiO 2 enhanced carbonated water on the gas-water ratio of the nano-SiO 2 enhanced carbonated water and the high-pressure physical properties of the heavy oil (density, viscosity, gas-oil ratio, CO 2 gas-oil ratio, volume expansion coefficient). In this example, change the 100% CO 2 saturation to 50% CO 2 saturation. The viscosity calculation results before and after multiple contact processes are shown in Table 1:

[0070] Table 1 Viscosity measurement results of heavy oil before and after contact at different CO 2 saturations;

[0071] Figure 2 This is the graph of the gas-water ratio of the nano-SiO 2 enhanced carbonated water changing with the number of contacts in the experimental method of the present invention. Figure 3 This is the graph of the gas-oil ratio of formation oil changing with the number of contacts in the experimental method of the present invention. Figure 4 This is the graph of the CO 2 gas-water ratio of the nano-SiO 2 enhanced carbonated water changing with the number of contacts in the experimental method of the present invention. Figure 5 This is the graph of the CO 2 gas-oil ratio of formation oil changing with the number of contacts in the experimental method of the present invention. Figure 6 This is the graph of the volume expansion coefficient of formation oil changing with the number of contacts in the experimental method of the present invention. Figure 7 This is the graph of the density of formation oil changing with the number of contacts in the experimental method of the present invention. As Figures 2 to 7 shown, compared with 50% CO2 Saturation, 100% CO 2 nano-SiO with saturation 2 After enhanced carbonated water contacts with heavy oil multiple times, the gas-oil ratio of heavy oil is higher under different contact times, and 100% CO 2 nano-SiO with saturation 2 After enhanced carbonated water contacts with heavy oil, the density and viscosity of heavy oil are lower, the volume expansion coefficient is larger, and the expansion and viscosity reduction effect is better, indicating that increasing the nano-SiO 2 CO in enhanced carbonated water 2 saturation can increase CO 2 from nano-SiO 2 mass transfer effect of enhanced carbonated water into heavy oil, and better improve the high-pressure physical properties of heavy oil.

Claims

1. Nano-silicon dioxide enhanced carbonized water-heavy oil multiple contact experimental device, characterized in that: Including fluid preparation system, multiple contact experiment system, test analysis system, temperature control system; The fluid preparation system is used to prepare fluids used in multiple contact experiments, including the preparation of nano-SiO2 enhanced carbonated water and the preparation of formation oil; The multiple contact experimental system is used to control the multiple contact between nano-SiO2 enhanced carbonated water and formation oil; The test and analysis system is used to test the properties of carbonized water enhanced by nano-SiO2 and the high-pressure physical properties of heavy oil after multiple contact processes; the properties of carbonized water enhanced by nano-SiO2 include gas-water ratio and CO2 gas-water ratio, and the high-pressure physical properties of heavy oil include density, viscosity, gas-oil ratio, CO2 gas-oil ratio, and volume expansion coefficient; The temperature control system is used to provide the temperature required for multiple contact experiments; The fluid preparation system includes a parallel connection of a heavy oil container, a CH4 container, a CO2 container, a nano-SiO2 enhanced carbonated water container, a CH4 gas cylinder and a CO2 gas cylinder; the tops of the heavy oil container, the CH4 container, the CO2 container and the nano-SiO2 enhanced carbonated water container are connected to the pipeline through a pressure gauge and a valve, and the bottoms are connected to a high-precision plunger pump through a valve and a pipeline, and the tops of the CH4 container and the CO2 container are connected to the CH4 gas cylinder and the CO2 gas cylinder respectively through a pressure gauge, a valve and a pipeline; The multiple contact experimental system includes a multiple contact model, a multiple contact model stirring device and a stirring block; one end of the multiple contact model is connected to the top of the nano-SiO2 enhanced carbonated water container through a pressure gauge, a valve and a pipeline, and the other end is connected to a high-precision plunger pump through a pipeline and a valve; the multiple contact model stirring device controls the stirring of the fluid in the multiple contact model; The test and analysis system includes a gas-liquid separator, a gas flow meter, a falling ball viscometer, a gas component analyzer, an electronic balance, a hand pump and several air bags; the top of the gas-liquid separator is connected to the top valve of the multiple contact model through a back pressure valve and a pipeline, the lower part of the gas-liquid separator is an outlet with a valve, and directly below the outlet is a liquid collection container. The liquid collection container is moved to the electronic balance for weighing, which is used to weigh the liquid mass and calculate the gas-liquid ratio; there is also an outlet on the upper part of the gas-liquid separator, which is connected to the gas flow meter. The outlet end of the gas flow meter is connected to a detachable and replaceable air bag through a pipeline, and the separated gas is collected by the air bag, and then the volume percentage of CH4 and CO2 in the separated gas is detected by the gas component analyzer; The temperature control system comprises a multiple contact model, a gas-liquid separator, a falling ball viscometer, a nano-SiO2 enhanced carbonated water container and a heavy oil container, and the outer side of the pipeline connecting the multiple contact model, the gas-liquid separator, the falling ball viscometer and the nano-SiO2 enhanced carbonated water container is wrapped with a heating belt for heating the above containers and the pipeline connecting the above containers; The top of the heavy oil container, CH4 container, CO2 container, nano-SiO2 enhanced carbonized water container and the multiple contact model are all connected to a vacuum pump. Before the experiment, the heavy oil container, CH4 container, CO2 container, nano-SiO2 enhanced carbonized water container and the multiple contact model are evacuated.

2. The nano-silicon dioxide enhanced carbonated water-heavy oil multiple contact experimental device according to claim 1, characterized in that: The multiple contact model is a cylindrical container device wrapped with an insulation sleeve, which is used to achieve the contact between nano-SiO2 enhanced carbonated water and formation oil; one end of the multiple contact model stirring device is fixed on the multiple contact model, and the other end is connected to a motor, and the multiple contact model is driven to rotate by the rotation of the motor, so as to stir the nano-SiO2 enhanced carbonated water and formation oil inside the multiple contact model.

3. The nano-silicon dioxide enhanced carbonated water-heavy oil multiple contact experimental device according to claim 1, characterized in that: A multiple contact model volume meter is also provided on the shell of the multiple contact model for intuitively displaying the volume change within the multiple contact model.

4. The nano-silicon dioxide enhanced carbonated water-heavy oil multiple contact experimental device according to claim 1, characterized in that: The rotation speed of the multiple contact model is 2 r / min; The total volume of the multiple contact model is greater than 400 ml.

5. The nano-silicon dioxide enhanced carbonated water-heavy oil multiple contact experimental device according to claim 1, characterized in that: A stirring block is placed in the multiple contact model, the volume of the stirring block is greater than 50 ml and the weight is not less than 200 g.

6. The nano-silicon dioxide enhanced carbonated water-heavy oil multiple contact experimental device according to claim 1, characterized in that: The standard volume of the gas bag is not less than 500 ml. The gas bag is evacuated before collecting gas for gas collection and gas component detection. One end of the falling ball viscometer is connected to the top valve of the multiple contact model through a pressure gauge, and the other end is connected to a back pressure valve, which is used to control the pressure of the exported fluid to remain under experimental conditions. The use conditions of the falling ball viscometer meet the normal operation at 50°C and 18MPa. It is used to measure the viscosity of the heavy oil before and after multiple contacts of nano-SiO2 enhanced carbonized water-heavy oil under high temperature and high pressure conditions. High temperature and high pressure refer to: the high temperature range is 30-50°C, and the high pressure range is 10-18 Mpa.

7. A nano-silicon dioxide enhanced carbonated water-heavy oil multiple contact experimental method, which is implemented by the nano-silicon dioxide enhanced carbonated water-heavy oil multiple contact experimental device according to any one of claims 1 to 6, characterized in that: The steps include: (1) Preparation of formation oil; determination of formation oil density ; (2) Prepare nano-SiO2 fluid; measure the density of nano-SiO2 fluid and record it as , introducing the prepared nano-SiO2 fluid into the nano-SiO2 enhanced carbonated water container; (3) preparing nano-SiO2 enhanced carbonated water; introducing all CO2 in the CO2 container into the nano-SiO2 enhanced carbonated water container through a pipeline, applying pressure to the nano-SiO2 enhanced carbonated water container by a high-precision plunger pump to dissolve CO2 into the nano-SiO2 fluid until the experimental pressure remains unchanged, thereby obtaining nano-SiO2 enhanced carbonated water; (4) Conduct multiple contact experiments between nano-SiO2-enhanced carbonized water and heavy oil; Before contact, introduce the prepared formation oil into the falling ball viscometer to measure the viscosity of the formation oil before contact. μ 0; Then the formation oil is introduced into the multiple contact model, and then the nano-SiO2 enhanced carbonated water is introduced into the multiple contact model, and the formation oil volume before the i-th contact is recorded. V 0i , record the formation oil volume after the ith contact V 1i , calculate the volume expansion coefficient ; During the process, the experimental pressure is kept constant by a high-precision plunger pump; The fluid in the multiple contact model is stirred by a multiple contact model stirring device, and the pressure in the multiple contact model is controlled during the process until it is stabilized at the experimental pressure, and the stirring is stopped and the mixture is left to stand for a period of time until oil and water are separated into layers; (5) Calculate the gas-water ratio of nano-SiO2 enhanced carbonized water after contact; Draw out the nano-SiO2 enhanced carbonized water from the lower end of the multiple contact model to the gas-liquid separator and record the initial reading of the gas flow meter at the beginning. V ai and gas flow meter reading after the separation process is completed V bi , collect the separated gas, and use the gas component analyzer to detect the volume percentage of CO2 in the gas separated by nano-SiO2 enhanced carbonization water, which is recorded as , used to calculate the CO2 gas-water ratio after contact with nano-SiO2 enhanced carbonized water; the mass of nano-SiO2 enhanced carbonized water after gas-liquid separation was weighed using an electronic balance and recorded as m wi , discharge all the nano-SiO2 enhanced carbonized water in the multiple contact model until oil is produced; (6) Calculate the gas-oil ratio of the heavy oil after contact; Drain some of the formation oil from the lower end of the multiple contact model to the gas-liquid separator. When the growth rate of the gas flow meter is stable, close the valve at the lower end of the gas-liquid separator and record the volume reading of the multiple contact model before starting the gas-oil ratio test. , after draining out some of the formation oil, close the multiple contact model valve and record the volume reading of the multiple contact model after the formation oil is drained out. , while recording the initial reading of the gas flow meter V ci and gas flow meter reading after the separation process is completed V di , use an electronic balance to weigh the contacted formation oil mass after gas separation m oi , collect the separated gas, and use the gas component analyzer to detect the volume percentage of CO2 in the separated gas of the formation oil after different contact times, recorded as ; (7) Repeat steps (4) to (6) to complete the multiple contact experiments between nano-SiO2 enhanced carbonated water and heavy oil; calculate the gas-water ratio of nano-SiO2 enhanced carbonated water at different contact times. , Gas-oil ratio of heavy oil , Density of formation oil , Volume expansion coefficient , Nano-SiO2 enhances the CO2 gas-water ratio of carbonated water , CO2 gas-oil ratio of heavy oil After the last contact, part of the heavy oil is led out from the bottom of the multiple contact model into the falling ball viscometer to measure the viscosity of the heavy oil after multiple contacts. μ ; The changing rules of the above parameters with the increase of contact times were analyzed, the mass transfer effect of nano-SiO2 enhanced carbonated water-heavy oil in multiple contact processes was studied, and the mechanism of nano-SiO2 enhanced carbonated water to improve heavy oil recovery was revealed; (8) Repeat steps (1) to (7) to change the property parameters of nano-SiO2 enhanced carbonated water, including mineralization, CO2 saturation, nano-SiO2 particle concentration, and salt type, and conduct multiple contact experiments between the nano-SiO2 enhanced carbonated water and heavy oil after the properties are changed to clarify the influence of the property parameters of nano-SiO2 enhanced carbonated water on the gas-water ratio of nano-SiO2 enhanced carbonated water and the high-pressure properties of heavy oil.

8. The nano-silicon dioxide enhanced carbonated water-heavy oil multiple contact experimental method according to claim 7, characterized in that: The ratio of the volume of nano-SiO2-enhanced carbonized water introduced into the multiple contact model each time to the volume of formation oil in the multiple contact model was 1:1; The standing time should be no less than 6 hours, until the oil and water separate into layers; The volume expansion coefficient of heavy oil after each contact is calculated according to formula (I): : （Ⅰ）; In formula (I), is the volume expansion coefficient of the formation oil after the ith contact, dimensionless; V 1i For the i After the first contact, all the formation oil volume after the nano-SiO2 enhanced carbonated water was extracted; V 0i For the i Second contact with nano-SiO2 enhanced formation oil volume before carbonation water.

9. The nano-silicon dioxide enhanced carbonated water-heavy oil multiple contact experimental method according to claim 8, characterized in that: The gas-water ratio of nano-SiO2 enhanced carbonated water after contact at different contact times was calculated by formula (II) ; （Ⅱ）; In formula (II), For the i Gas-water ratio of nano-SiO2 enhanced carbonated water after the first contact, ml / ml; V bi is the flow meter reading after the gas-liquid separation process is completed, ml; V ai is the initial reading of the flow meter at the beginning of gas-liquid separation, ml; m wi For the i The mass of nano-SiO2 enhanced carbonated water collected by the separator after the first contact, g; The density of carbonated water enhanced by nano-SiO2 g / cm 3 ; The CO2 gas-water ratio of the carbonized water enhanced by nano-SiO2 after contact was calculated according to formula (III) ; （Ⅲ）; In formula (III), For the i The volume percentage of CO2 in the gas separated by carbonization enhanced by nano-SiO2 after the first contact, dimensionless; For the i CO2 gas-water ratio of nano-SiO2 enhanced carbonated water after the first contact, ml / ml; The volume of formation oil extracted per contact was 15-25 ml.

10. The nano-silicon dioxide enhanced carbonated water-heavy oil multiple contact experimental method according to claim 8, characterized in that: The gas-oil ratio of heavy oil after each contact is calculated by the following formula (IV): ; （Ⅳ）; In formula (IV), For the i Gas-oil ratio of heavy oil after the first contact, ml / ml; V ci is the initial reading of the flow meter at the beginning of gas-liquid separation, ml; V di is the flow meter reading after the gas-liquid separation process is completed, ml; m oi For the i Mass of formation oil collected during the first contact gas-liquid separation process, g; is the density of degassed formation oil, g / cm 3 ; The density of the formation oil after each contact is calculated according to formula (V): : （Ⅴ）; In formula (V), is the formation oil density after the ith contact, g / cm 3 ; For the i The volume indication of the multiple contact model before the start of the first contact to test the gas-oil ratio, ml; For the i The volume of the multiple contact model after the formation oil is extracted after the first contact, ml; Calculate the CO2 gas-oil ratio of heavy oil after contact according to formula (VI): : （Ⅵ）; In formula (VI), For the i CO2 gas-to-oil ratio of heavy oil after the first contact, ml / ml; For the i The volume percentage of CO2 in the heavy oil separation gas after the first contact, dimensionless.

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