A three-dimensional visualization physical simulation device and method for gas injection gravity drive

Abstract

The present invention discloses a three-dimensional visualized physical simulation device and method for gas injection gravity drive, the device comprising a sample injection system, a reservoir simulation system, a production system and a monitoring system; the reservoir simulation system comprises a box, a multi-angle adjustment bracket, a saturation electrode and a bubble-type electronic angle measuring instrument. The multi-angle adjustment bracket can realize a variable inclination range, so as to study the influence of the inclination range on the interface stability and displacement efficiency in the experimental results. The sample injection system injects simulated oil and simulated edge and bottom water into the box through the oil and water injection port, and injects simulated gas into the box through the gas injection port; the production system is connected to the liquid outlet to measure the amount of oil, water and gas produced. The present invention establishes a three-dimensional physical model that takes into account water body energy, reservoir physical properties, formation inclination, crude oil viscosity and gas injection rate, that is, the simulation device of the present invention, which provides a basis for the study of the main controlling factors of gas injection in gas cap gravity drive of complex oil reservoirs.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield exploitation, in particular to a large-scale three-dimensional macroscopic visualization physical simulation experimental device and an experimental method for gas injection gravity drive. Background Art

[0002] Through the study of the structural characteristics of my country's oil reservoirs, it is found that a large part of the oil reservoirs have structural characteristics such as large reservoir inclination and edge and bottom water. When developing and utilizing such oil reservoirs, due to the large difference in oil-water viscosity and the poor flowability of crude oil, it is easy to make the edge water advance faster, resulting in serious flooding, which has a great impact on the development effect of the oil reservoir. The inclined structures such as anticline structures and buried hill structures in such oil reservoirs will form "attic oil" at the top of the reservoir during the development process, which will also have a certain impact on the development effect of the reservoir. In view of this phenomenon, when developing and utilizing such oil reservoirs, the method of injecting gas at the top of the reservoir can greatly improve the recovery rate of such oil reservoirs. The top gas injection method can effectively control the oil-gas-water interface and maintain the reservoir pressure. At present, it has achieved good results in the field practice of some domestic oil fields.

[0003] However, the key mechanisms such as the migration characteristics of the gas injection profile, the macroscopic sweep law, and the mechanism of remaining oil utilization during the top gas injection process are not clearly understood, resulting in uncertainty in the current field practice of top gas injection to enhance oil recovery in such reservoirs. Physical simulation is an important research method for studying the gas injection to enhance oil recovery in such reservoirs. During the experiment, the actual reservoir geological parameters and seepage-related parameters are converted into the size required by the laboratory according to a certain ratio, and the development dynamics of the reservoir can be predicted through physical simulation experiments.

[0004] The existing patent CN202111088713.4 discloses a simulation experimental device and method for gas-assisted viscosity reducer gravity-assisted flooding at different inclination angles. CN201821119469.7 discloses a three-dimensional large flat sand filling model, focusing on studying the seepage characteristics of multiphase fluids, but the experimental device cannot be visualized and mainly relies on the analysis of experimental data to obtain results. CN201811391120.3 discloses a three-dimensional visualized sand filling model and its preparation method, focusing on adjusting the permeability difference between layers of the three-dimensional model to simulate the heterogeneity of various oil reservoirs, but this experimental device cannot consider the effect of the formation inclination and cannot simulate the influence of the formation inclination on the gas injection development process. CN201510724935.9 discloses a visualization experimental device and method for simulating gas injection in fracture-cavity carbonate reservoirs. This physical model device is too small in scale and cannot withstand high pressure, and cannot simulate the three-dimensional oil-gas-water transport dynamics during the gas injection flooding process at the top of the reservoir under formation conditions. Summary of the invention

[0005] The purpose of the present invention is to provide a three-dimensional visualized physical simulation device for gas injection gravity drive and a corresponding experimental method in view of the above-mentioned deficiencies of the existing top gas injection gravity drive simulation experimental device.

[0006] The gas injection gravity drive three-dimensional visualized physical simulation device provided by the present invention comprises a sample injection system, a reservoir simulation system, a production system and a monitoring system.

[0007] The reservoir simulation system includes a box, a multi-angle adjustment bracket, a saturation electrode and a bubble-type electronic angle measuring instrument. The multi-angle adjustment bracket includes an inclination adjustment mechanism arranged at the bottom of the box and bearings arranged at the left and right ends of the box; the inclination adjustment mechanism consists of a base and an arc bracket, the arc bracket opens upward, the bottom of the arc bracket is installed on the base in a way that the left and right inclination angles can be adjusted, a support plate is fixed on each end surface of the arc bracket, and the bearings at the left and right ends of the box are fixed on two support plates respectively; under the action of the bearing, the box can rotate 180° around the bearing. The bubble-type electronic angle measuring instrument is arranged on one of the support plates. Visual sapphire windows are arranged on the front and back of the box. Removable metal cover plates are arranged on the top and bottom surfaces of the box. Equidistant screw holes are arranged on the metal cover plates on the top and bottom surfaces of the box, and each screw hole is equipped with a reinforced metal screw, and a high-temperature resistant sealing gasket is arranged between the metal cover plate and the box body. Two parallel detachable filter plates are arranged in the middle of the box, and the filter plates are parallel to the front of the box. The space between the two filter plates is filled with quartz sand required for the experiment. The saturation electrodes are arranged in multiple groups and extend inward from the metal cover plate on the top of the box to the inside of the box, and at the same time, they are sealed and connected with the intersection of the metal cover plate on the top of the box. The box is also provided with oil and water injection ports, gas injection ports and liquid outlets; the entire reservoir simulation system is arranged inside a floor-standing oven. The visual observation window of the reservoir simulation system model is set by sapphire, and the sealing ring of the model adopts a graphite combination gasket. The model can be used under conditions of up to 80MPa and a maximum temperature resistance of 280 degrees Celsius.

[0008] The sample injection system includes: a constant speed constant pressure displacement pump, a simulated gas injection device, a simulated edge and bottom water device, a simulated oil device, and a back pressure constant pressure device. The simulated gas injection device, the simulated edge and bottom water device, the simulated oil device, and the back pressure constant pressure device are all connected to the constant speed constant pressure displacement pump through pipelines and valves. The gas source device is connected to the simulated gas injection device through a three-way valve, and the back pressure constant pressure device is connected to the back pressure valve through a back pressure pressure sensor. The sample injection system injects simulated oil and simulated edge and bottom water into the box through the oil and water injection port, and injects simulated gas into the box through the gas injection port.

[0009] The output system includes an oil-water metering device and a gas metering device. The oil-water metering device is connected to the liquid outlet of the box through a pipeline, and the gas metering device is connected to the oil-water metering device through a pipeline. The oil, gas and water are collected and measured by a measuring cylinder and a drainage gas collecting device. The output system is connected to the liquid outlet to measure the amount of oil, water and gas produced.

[0010] The monitoring system comprises a back pressure sensor, an inlet pressure sensor, an outlet pressure sensor, a pressure monitoring system and a real-time video recording device, and the back pressure sensor, the inlet pressure sensor and the outlet pressure sensor are all connected to the pressure monitoring system.

[0011] A preferred structural mode is that a protruding connector is provided on the upper surface of the base, and the bottom of the arc bracket is fixed to the connector by screws; the connector is two vertically arranged metal sheets, the bottom ends of the metal sheets are fixed to the base, the two metal sheets are arranged in parallel, the bottom end of the arc bracket is installed in the gap between the two metal sheets, and the arc bracket is fixed to the two metal sheets by screws. There are two arc brackets, which are arranged in parallel with each other, and each arc bracket is connected to the base by two connectors; the two end surfaces of the two arc brackets on the same side are fixed to the support plate at the same time.

[0012] The method for conducting an experiment using the above-mentioned gas injection gravity drive three-dimensional visual physical simulation device is as follows:

[0013] S1. Prepare simulated oil and simulated formation water, dye the simulated formation water and simulated oil with methyl blue and Sudan red respectively; the experimental gas is high-pressure nitrogen; fill the box of the reservoir simulation system with quartz sand, compact it with vibration and test whether the permeability meets the order of magnitude designed in the experimental plan. If not, adjust the quartz sand size standard and refill it.

[0014] S2. Connect the experimental device and check its tightness; then evacuate the experimental device and fully saturate it with simulated oil to the formation pressure of the simulated experiment, and record the saturated oil volume.

[0015] S3. The oven temperature is raised to the target temperature of the simulation experiment, and the back pressure of the experimental device is adjusted to the target pressure of the experiment; after changing the inclination angle of the profile model to the angle required by different experimental schemes, a constant pressure and constant speed displacement pump is used to simulate the water-to-oil drive process of strong edge water; the injection speed required by different experimental schemes is adjusted to represent the energy of edge water in different reservoirs, and the injected water volume is recorded in real time. The oil well is simulated through the liquid outlet on the upper part of the box, the water volume and oil volume driven out are recorded, the saturation is recorded, the outlet water content is calculated, and the interface changes are recorded through a real-time video recording device.

[0016] S4. When the water content at the upper liquid outlet of the box reaches 90%, keep the water injection at the bottom unchanged and start injecting nitrogen at the top. Record the injected water and gas volume, produced gas volume, water volume and oil volume, record the saturation, calculate the outlet water content, and record the interface changes through a real-time video recording device.

[0017] S5. When the water content at the liquid outlet reaches above 98%, the experiment is stopped and the gas-assisted gravity drive experiment is completed.

[0018] S6. Data processing, as follows:

[0019] (1) According to the data obtained from different experimental schemes, the gravity number is calculated using the following formula:

[0020]

[0021] Where N G is the gravity number; v is the seepage velocity, m / s; μ is the fluid viscosity, mPa·s; Δρ is the gas-oil density difference, g / cm 3 ; g is the acceleration due to gravity, m / s 2 ; k is the permeability, 10 -3 μm 2 ; C is the constant generated by unit conversion, C = 8.64 × 10 -5 ; α is the formation inclination. Seepage velocity v It is the velocity of the oil phase inside the experimental device and can be calculated by the oil volume and time recorded at the outlet. Fluid viscosity μ is the viscosity of the oil and gas used in the experiment. Permeability k is obtained by using the formula based on the experimental data.

[0022] Draw a graph showing the relationship between the gravity number and the gas drive recovery degree;

[0023] (2) Based on the data obtained from different experimental schemes, the capillary number is calculated using the following formula:

[0024]

[0025] Where N C is the capillary number; v is the seepage velocity, m / s; μ is the fluid viscosity, mPa·s; σ is the interfacial tension, N / m; α is the formation inclination. The interfacial tension σ is obtained through a separate test on simulated oil.

[0026] Draw a graph showing the relationship between the number of capillary tubes and the degree of gas drive recovery;

[0027] (3) Based on the data obtained from different experimental schemes, the Bond number is calculated using the following formula:

[0028]

[0029] Where N b is the Bond number; σ is the interfacial tension, N / m; Δρ is the gas-oil density difference, g / cm 3 ; g is the acceleration due to gravity, m / s 2 ; K is permeability, 10 -3 μm 2 ; φ is porosity; α is formation dip;

[0030] Draw a graph showing the relationship between the Bond number and the gas drive recovery degree;

[0031] (4) Based on the five-element stable drive coefficient formula:

[0032]

[0033] Where k is the permeability, 10 -3 μm 2 ; θ is the formation dip; μ is the fluid viscosity, mPa·s; τ is the water volume multiple; v is the seepage velocity, m / s; the maximum or minimum value refers to the maximum or minimum value in all experimental data.

[0034] Substitute the sensitive parameters in different experimental schemes to obtain the calculated values ​​of the parameters of the five-element stable drive coefficient, and draw the relationship diagram between the five-element stable drive coefficient and the gas drive recovery degree according to the five-element stable drive coefficient formula;

[0035] (6) Calculate the oil displacement efficiency E using the following formula D :

[0036]

[0037] In the formula, Q O The amount of oil displaced during the experiment, ml; S O is the oil saturation; V is the volume of the reservoir simulation system, cm 3 ; φ is the porosity of the box after filling with sand; using E D Evaluating the sweep efficiency of the swept area of ​​the gravity stability profile can more accurately evaluate the mobilization capacity of different injection and production systems on reservoir pores.

[0038] The dimensionless parameters capillary number, Bond number and gravity number are used to characterize the gas cap gravity drive process. The oil and gas interface is controlled by gas driving force, gravity, capillary force, water driving force and viscosity force. When the interaction of various forces reaches a dynamic balance, the fingering can be suppressed, so that the oil and gas interface remains basically stable during the displacement. Various criteria are quantitative characterizations of the different forces acting on the oil and gas interface, and the parameters considered by different criteria are different. Compared with the capillary number and Bond number, the gravity number and the five-element stable drive coefficient consider more comprehensive parameters, which can better reflect the differences in formation, fluid and production parameters, thereby more accurately describing the flow characteristics of the fluid during the gas cap gravity drive development process.

[0039] Compared with the prior art, the present invention is beneficial in that:

[0040] The large-scale three-dimensional macroscopic visualization physical simulation experimental device for gas injection gravity drive designed by the present invention can meet the requirements of high temperature and high pressure experiments, and can take into account sensitive factors such as water body energy, edge and bottom water distribution, reservoir physical properties, formation inclination, crude oil viscosity and gas injection rate. Under different experimental design schemes, the effects of water body energy, reservoir physical properties, formation inclination, crude oil viscosity and gas injection rate on recovery rate and oil-gas interface stability are studied. Through saturation monitoring and visualized profile observation, the gravity drive process at the top of the reservoir is accurately simulated, thereby providing guidance for understanding the mechanism of improving recovery rate by gas injection gravity drive at the top of complex reservoirs.

[0041] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 , schematic diagram of the three-dimensional visual physical simulation device of gas injection gravity drive of the present invention.

[0043] Figure 2 , schematic diagram of the reservoir simulation system structure of the present invention.

[0044] Figure 3 , a schematic diagram of the internal structure of the manual rotating device of the present invention.

[0045] Figure 4 , a cross-sectional model diagram of the reservoir simulation system of the present invention.

[0046] Figure 5 , changes in the degree of recovery and outlet water content during the basic plan experiment.

[0047] Figure 6 , the changes in the degree of extraction and outlet water content during the experimental process of increasing the water volume multiple (500 times).

[0048] Figure 7, changes in oil recovery degree and outlet water content during the experimental process of increasing oil viscosity (90cP).

[0049] Figure 8 , changes in the degree of recovery and outlet water content during the experimental process of the formation inclination 0°.

[0050] Fig. 9 , changes in recovery degree and outlet water content during the experimental process of the gas injection rate of 0.2HCPV / a (sand particle diameter 0.125-0.25mm).

[0051] Fig.10 , changes in recovery degree and outlet water content during the experimental process of the gas injection rate of 0.2HCPV / a (sand particle diameter 1-2mm).

[0052] Fig.11 , changes in the degree of recovery and outlet water content during the experimental process of the 0° inclination (sand grain diameter 0.125-0.25mm) scheme.

[0053] Fig.12 , changes in the degree of recovery and outlet water content during the experimental process of the oil viscosity 90cP (sand particle diameter 0.125-0.25mm) scheme.

[0054] Fig.13 , the changes in the degree of extraction and outlet water content during the experimental process of the 500 times water body (sand particle diameter 0.125-0.25mm) scheme.

[0055] Fig.14 , the changes in the degree of extraction and outlet moisture content during the experimental process of the basic scheme (sand particle diameter 0.125-0.25mm).

[0056] Numbers in the figure:

[0057] Constant speed and constant pressure displacement pump 1, valve 2, valve 3, valve 4, valve 5, simulated gas injection device 6, back pressure constant pressure device 7, simulated edge and bottom water device 8, simulated oil device 9, valve 10, valve 11, valve 12, three-way valve 13, gas source device 14, back pressure pressure sensor 15, back pressure valve 16, reservoir simulation system 17, floor-standing oven 18, inlet pressure sensor 19, outlet pressure sensor 20, pressure monitoring system 21, oil and water metering device 22, gas metering device 23, real-time video recording device 24, box 25, saturation electrode 26, bubble type electronic angle measuring instrument 27, bearing 28, base 29, arc bracket 30, connector 31, screw 32, support plate 33, manual rotation device 34, sapphire window 35, metal cover plate 36, metal screw 37, screw 38, front panel 39, back panel 40, square frame 41, angle fixing bracket 42, hole 43, hole 44. DETAILED DESCRIPTION

[0058] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0059] like Figure 1 and Figure 2 As shown, the gas injection gravity drive three-dimensional visual physical simulation device provided by the invention includes a sample injection system, a reservoir simulation system, a production system and a monitoring system.

[0060] The sample injection system includes: a constant speed constant pressure displacement pump 1 (working pressure is 0MPa to 70MPa, flow rate range is 0.001mL / min to 10mL / min), a simulated gas injection device 6, a simulated edge and bottom water device 8, a simulated oil device 9, and a back pressure constant pressure device 7. The simulated gas injection device 6, the simulated edge and bottom water device 8, the simulated oil device 9, and the back pressure constant pressure device 7 are all connected to the constant speed constant pressure displacement pump through pipelines and valves (including valves 2, 3, 4, and 5). The gas source device 14 is connected to the simulated gas injection device 6 through a three-way valve 13. A valve 12 is arranged between the simulated gas injection device 6 and the three-way valve 13. The back pressure constant pressure device 7 is connected to the back pressure valve 16 through a back pressure pressure sensor 15. A valve 10 is arranged on the pipeline connecting the simulated oil device 9 and the reservoir simulation system, and a valve 11 is arranged on the pipeline connecting the simulated edge and bottom water device 8 and the reservoir simulation system. The sample injection system is used to inject simulated oil, simulated edge and bottom water and simulated gas into the reservoir simulation system 17. The reservoir simulation system 17 is arranged in a floor-standing oven 18. The maximum test temperature of the oven is 200°C, and the experimental device can be heated to the formation temperature.

[0061] The monitoring system includes a back pressure sensor 15, an inlet pressure sensor 19, an outlet pressure sensor 20, a pressure monitoring system 21 and a real-time video recording device 24. The inlet pressure sensor 19 is arranged at the oil and water inlet position of the reservoir simulation system 17. The outlet pressure sensor 20 is arranged at the liquid outlet position of the reservoir simulation system 17. The back pressure sensor 15, the inlet pressure sensor 19 and the outlet pressure sensor 20 are all connected to the pressure monitoring system. The real-time video recording device 24 records the entire experimental process through a high-definition video camera.

[0062] The production system includes an oil-water metering device 22 and a gas metering device 23. The oil-water metering device 22 is connected to the liquid outlet of the reservoir simulation system 17 through a pipeline. The gas metering device 23 is connected to the oil-water metering device 22 through a pipeline. The oil, gas and water are mainly collected and measured by a measuring cylinder and a drainage gas collecting device.

[0063] The specific structure of the reservoir simulation system 17 is as follows Figure 2As shown, it includes a box 25, a multi-angle adjustment bracket, a saturation electrode 26 and a bubble-type electronic angle measuring instrument 27. The multi-angle adjustment bracket is connected to the bubble-type electronic angle measuring instrument, and the angle between the bracket and the overall experimental device is adjusted to the real formation dip angle through the angle displayed by the angle measuring instrument. The multi-angle adjustment bracket includes a dip adjustment mechanism arranged at the bottom of the box and bearings 28 arranged at the left and right ends of the box; the dip adjustment mechanism is composed of a base 29 and an arc bracket 30, the arc bracket 30 opens upward, the bottom of the arc bracket is installed on the base, and the angle between the base and the arc bracket can be adjusted, thereby simulating the change of the formation dip angle. The specific connection method between the arc bracket and the base is: a raised connecting piece 31 is arranged on the upper surface of the base 29, and the bottom of the arc bracket is fixed to the connecting piece by screws 32. The connecting piece is two vertically arranged metal sheets, the bottom end of the metal sheet is fixed on the base, the two metal sheets are arranged in parallel, the bottom end of the arc bracket is installed in the gap between the two metal sheets, and the arc bracket is fixed to the two metal sheets by screws. Preferably, there can be two arc-shaped brackets, which are arranged parallel to each other, and each arc-shaped bracket is connected to the base through two connecting parts 31 and an angle fixing bracket 42 located between the two connecting parts. When it is necessary to adjust the angle between the arc-shaped bracket and the base, first loosen the screws, then adjust the angle, and then fix it with screws. A support plate 33 is fixed to each of the two end surfaces of the arc-shaped bracket. A bearing 28 on one side of the box is fixed on one of the support plates, and a bubble-type electronic angle measuring instrument 27 is installed on the support plate. A manual rotating device 34 is installed on the other support plate. The manual rotating device is connected to one end of the bearing 28, and the bearing 28 is driven to rotate through the manual rotating device, thereby driving the box to rotate. Under the rotation of the bearing, the box can rotate 180° around the bearing. The internal structure and transmission mechanism of the manual rotating device 34 can be seen in Figure 3 In the figure, one end of the connecting rod 341 is connected to the manual turntable, and the other end is connected to gear 1 342, gear 1 342 is connected to gear 2 343, gear 2 343 is connected to gear 3 344, gear 3 344 is connected to gear 4 345, and gear 4 345 is connected to bearing 28. Manually rotating the turntable drives the box 25 to rotate through gear transmission. Reverse rotation of the turntable can achieve reverse rotation of the box 25.

[0064] The box is composed of a front panel 39, a back panel 40 and a square frame 41 between the front panel and the back panel. Transparent filter plates (not shown) are installed on the front and back of the square frame, and the gap between the two filter plates is used to fill quartz sand. The front of the square frame is spliced ​​with the front panel, and the back of the square frame is spliced ​​with the back panel. The front of the square frame is fixedly connected to the front panel by screws 38, and the back of the square frame is fixedly connected to the back panel to form a complete box. The top and bottom square frames of the box are opened at corresponding positions and sealed by a detachable metal cover plate 36. The metal cover plates on the top and bottom surfaces of the box are provided with equidistant screw holes, each of which is provided with a reinforced metal screw 37, and a sealing gasket is provided between the metal cover plate and the box body. Visual sapphire windows 35 are provided on the front and back panels of the box. Three holes 43 are provided on the cover plate 36 on the top surface of the box. In the present invention, only two holes need to be used as gas injection ports and liquid outlets at the same time, and the remaining holes are sealed. Different holes can be replaced when the box is tilted to the left or right. There are two holes 44 on one side of the box, and only one hole is selectively used as the oil and water injection port in the present invention. The saturation electrodes 26 are provided in multiple groups and extend inwardly from the metal cover plate on the top surface of the box to the inside of the box, while maintaining a sealed connection with the intersection of the metal cover plate on the top surface of the box.

[0065] The box can simulate high temperature and high pressure under formation conditions (maximum pressure 70MPa, maximum temperature 150°C); considering the impact of high temperature on the experimental device, the visualization window of the box is made of sapphire, and the sealing gaskets, rubber rings in the experimental simulation device and the pipelines connecting the experimental device can withstand high temperature and high pressure.

[0066] The method for conducting an experiment using the above-mentioned gas injection gravity drive three-dimensional visual physical simulation device is as follows:

[0067] S1. According to the actual formation conditions and experimental requirements, simulated oil and formation water of different viscosities and quartz sand of different diameters are selected and prepared. The experimental gas is high-pressure nitrogen. The simulated formation water and simulated oil are dyed with methyl blue and Sudan red respectively to observe the distribution of oil and water in different experimental stages. The prepared quartz sand is filled into the model for vibration compaction and the permeability is tested to see if it meets the order of magnitude of the experimental design. If not, the quartz sand size standard needs to be adjusted and refilled.

[0068] S2. Connect the experimental device and check its tightness. After the inspection, evacuate the experimental device and use a constant pressure and constant speed displacement pump to fully saturate the simulated oil with the viscosity required by the experimental plan to the formation pressure of the simulated experiment, and record the saturated oil volume.

[0069] S3. The oven temperature is raised to the target temperature of the simulation experiment, and the back pressure of the experimental device is adjusted to the target pressure of the experiment; after changing the inclination angle of the profile model to the angle required by different experimental schemes, a constant pressure and constant speed displacement pump is used to simulate the water-to-oil drive process of strong edge water; the injection speed required by different experimental schemes is adjusted to represent the energy of edge water in different reservoirs, and the injected water volume is recorded in real time. The oil well is simulated through the liquid outlet on the upper part of the box, the water volume and oil volume driven out are recorded, the saturation is recorded, the outlet water content is calculated, and the interface changes are recorded through a real-time video recording device.

[0070] S4. When the water content at the upper liquid outlet of the box reaches 90%, keep the water injection at the bottom unchanged and start injecting nitrogen at the top. Record the injected water and gas volume, produced gas volume, water volume and oil volume, record the saturation, calculate the outlet water content, and record the interface changes through a real-time video recording device.

[0071] S5. When the water content at the liquid outlet reaches above 98%, the experiment is stopped and the gas-assisted gravity drive experiment is completed.

[0072] The box section model of the reservoir simulation system in the experimental device is placed in the spatial rectangular coordinate system, such as Figure 4 As shown. 1 is the initial oil-gas interface, h 2 For top gas injection displacement t 1 The oil-gas interface after time. The shaded part in the figure is the area A that the oil-gas interface passes through during the displacement process. Project one side of the model shadow into the xy plane to locate the polygon composed of points abcdef. The method for calculating the area of ​​irregular figures written by MATLAB software can be used to obtain the area A of the shaded part. The oil-gas interface is defined by h 1 Move to h 2 The model volume included is V = Ad, where d is the thickness of the model, cm. Therefore, the oil recovery efficiency of top gas injection gravity drive is Where Q O The amount of oil displaced during the experiment, ml; S O is the oil saturation; V is the model volume, cm 3 ; φ is the model porosity. D Evaluating the sweep efficiency of the swept area of ​​the gravity stability profile can more accurately evaluate the mobilization capacity of different injection and production systems on reservoir pores.

[0073] By designing experimental schemes under different sensitive conditions, the influence of different sensitive factors on the experimental results is studied, and the characterization parameters and judgment standard limits of the gas cap gravity drive interface stability are established.

[0074] In this embodiment, 12 simulation experiments are designed, and the specific experimental scheme is shown in Table 1.

[0075]

[0076] Among them, √ is the sensitive parameter changed in this simulation experiment.

[0077] The viscosity of crude oil is changed in order to study the effect of crude oil viscosity on the recovery degree and interface stability in the experimental results.

[0078] The reservoir properties are changed in order to study the effects of reservoir properties on recovery degree, gas drive breakthrough time and interface stability in the experimental results.

[0079] The inclination angle range (0-180°) was varied to study the effect of the inclination angle range on the interface stability and displacement efficiency in the experimental results.

[0080] The water volume multiple was changed to study the effect of water volume multiple on the time of gas injection breakthrough in the experimental results and to observe the interface stability.

[0081] The gas injection rate is changed in order to study the relationship between different gas injection rates and interface stability and oil recovery efficiency in the experimental results.

[0082] In this embodiment, the specific parameter settings of the 12 simulation experiments are shown in Table 2.

[0083] Table 2. Experimental parameter design

[0084]

[0085] The experimental test results are as follows:

[0086] (1) The first simulation experiment, the experimental data of the basic scheme are shown in Table 3 and Figure 5 The blank space of the gas injection multiple in the following Table 3-14 indicates that no gas was injected.

[0087] Table 3. Basic solution experimental test results data

[0088]

[0089]

[0090] (2) The experimental data of the second simulation experiment with variable water volume multiples are shown in Tables 4 and Figure 6 .

[0091] Table 4. Test results of increasing water volume multiples

[0092]

[0093]

[0094] By comparing with the experimental data of the basic scheme, it can be found that the larger the water body multiple is, the earlier the water breakthrough time is (0.49HPV breakthrough for the basic scheme, 0.33HPV breakthrough when the water body multiple is increased), and the recovery degree is low when the outlet water content is 90% (56.57% for the basic scheme, 52.76% when the water body multiple is increased). Through the profile changes, it can be found that the interface stability is worse when the water body multiple is increased; after top gas injection, the larger the water body multiple is, the slower the injected gas breakthrough becomes due to the influence of water body energy, and the gas drive recovery degree increases. The gas drive recovery degree increases from 52.76% to 66.64%, an increase of 13.88%, which is 20.83% higher than the final recovery degree (increased recovery degree / final recovery degree).

[0095] (3) The experimental data of the third simulation experiment with variable oil viscosity are shown in Table 5 and Figure 7 .

[0096] Table 5. Test results of increasing oil viscosity experiment

[0097]

[0098]

[0099] By comparing the experimental data with the basic scheme, it can be found that the greater the oil viscosity, the earlier the water breakthrough time (0.49HPV breakthrough for the basic scheme, 0.37HPV breakthrough when the oil viscosity is increased), the recovery degree is low when the outlet water content is 90% (56.57% for the basic scheme, 40.61% when the oil viscosity is increased), and through the profile changes, it can be found that the interface stability is worse when the oil viscosity is increased; due to the unstable interface during the water flooding process, the increased oil viscosity group has serious water channeling. After the top gas injection, the outlet water content did not immediately drop to the lowest compared with the first two groups of experiments, but It is a slow decrease and then a gradual increase, which results in a relatively stable gas drive process with better results and a more obvious increase in recovery: the recovery of the basic gas drive solution increased from 56.57% to 64.37%, an increase of 7.8%, and an increase of 12.12% over the final recovery (increased recovery / final recovery); the recovery of the gas drive solution with increased oil viscosity increased from 40.61% to 56.53%, an increase of 15.92%, and an increase of 28.16% over the final recovery (increased recovery / final recovery). But overall, the recovery is low.

[0100] (4) The experimental data of the fourth simulation experiment, the formation dip angle 0° scheme, are shown in Tables 6 and Figure 8 .

[0101] Table 6. Experimental test results of formation dip angle 0°

[0102]

[0103]

[0104] By comparing with the experimental data of the basic scheme, it can be found that when the formation dip is 0°, the water breakthrough time becomes earlier, but the change is not obvious (0.49HPV breakthrough for the basic scheme, 0.46HPV breakthrough when the formation dip is 0°), and the recovery degree is low when the outlet water content is 90% (56.57% for the basic scheme, 51.51% when the formation dip is 0°), and through the profile change, it can be found that the stability of the oil-water interface is slightly worse when the formation dip is 0°; after top gas injection, it can be found by observing the profile that natural gas first gathers at the top to form a gas cap, and then the gas cap drives oil, and the gas-oil interface is stable, the gas breakthrough is late, and in the gas Before the breakthrough, the outlet water content has been stable at a low value. After the gas breakthrough, the outlet water content increased rapidly, so the gas drive recovery rate when the formation dip is 0° is significantly improved: the gas drive recovery rate of the basic scheme increased from 56.57% to 64.37%, an increase of 7.8%, and an increase of 12.12% over the final recovery rate (increased recovery rate / final recovery rate). When the formation dip is 0°, the gas drive recovery rate increased from 51.51% to 82.04%, an increase of 30.53%, and an increase of 37.21% over the final recovery rate (increased recovery rate / final recovery rate).

[0105] (5) The experimental data of the fifth simulation experiment, which increased the gas injection rate (quartz sand diameter of about 0.125-0.25 mm), are shown in Tables 7 and Fig. 9 .

[0106] Table 7. Experimental test results of gas injection rate 0.2HCPV / a (sand particle diameter 0.125-0.25mm)

[0107]

[0108] By comparing the experimental data with the basic scheme, it can be found that when the gas injection rate is 0.2HCPV / a, the experimental effect of the water drive stage is not much different from that of the basic scheme, which verifies the comparability of the experiment (the basic scheme broke through at 0.49HPV, and the recovery degree was 47.83% at the time of breakthrough. This breakthrough was at 0.41HPV, and the recovery degree was 43.25%; when the basic scheme was injected with water at 0.72HPV, the outlet water content reached 90%, and the recovery degree was 56.57% at this time. When the water was injected at 0.68HPV in this scheme, the outlet water content reached 90%, and the recovery degree was 50.03% at this time). After top gas injection, it can be seen from the figure that after increasing the gas injection rate, the gas drive sweep efficiency is worse, and the oil-gas interface shows an unstable drive phenomenon. However, as the displacement proceeds, the oil-gas interface will become more and more stable. Ultimately, most of the oil is concentrated in the upper left part of the oil production well and the lower right part of the gas injection well. The final recovery rate is reduced compared with the basic plan (the final recovery rate of the basic plan is 64.37%, and the result this time is 58.17%), but the interface effect changes significantly.

[0109] (6) The experimental data of the sixth simulation experiment, which increased the gas injection rate (quartz sand diameter of about 1-2 mm), are shown in Tables 8 and Fig.10 .

[0110] Table 8. Experimental test results of gas injection rate 0.2HCPV / a (sand particle diameter 1-2mm)

[0111]

[0112] By comparing the experimental data of Scheme (5), it can be found that after top gas injection, as can be seen from the figure, after increasing the diameter of the sand filling particles, the oil-gas interface is much more stable than that of Scheme 5. Although the gas breakthrough is also very early, due to the stability of the interface, the water content at the outlet increases very slowly, resulting in an increase in the overall recovery rate.

[0113] (7) The seventh simulation experiment, the formation dip angle is 0°, the quartz sand diameter is about 0.125-0.25 mm. The experimental data of the scheme are shown in Table 9 and Fig.11 .

[0114] Table 9. Experimental test results at 0° inclination (sand grain diameter 0.125-0.25 mm)

[0115]

[0116] By comparing the experimental data of the quartz sand with a diameter of about 1-2mm in the fourth plan with a formation dip angle of 0°, it can be found that when the fine sand is replaced, the water breakthrough time becomes earlier (0.46HPV breakthrough in the fourth plan, 0.23HPV breakthrough in this plan), and the recovery degree is lower when the outlet water content is 90% (51.51% in the fourth plan, 43.36% in this plan). It can be found through the profile changes that the stability of the oil-water interface in this experiment is very poor. After the water drive starts, most of the water flows directly to the outlet well, resulting in an earlier water breakthrough time and a faster increase in water content. As the water drive proceeds, the water is drawn to the well by gravity. When it reaches the bottom of the formation, the water content at the outlet begins to rise slowly; after gas injection at the top, it can be found by observing the profile that the gas-oil interface is unstable and the gas breaks through early. Due to the instability of the oil-water interface, the oil-water interfaces on the two sides of the profile are asymmetric. After water breaks through from one side, a large amount of oil cannot be recovered on the other side. Even after gas injection at the top until the end of the experiment, the oil-gas-water interface on the other side of the profile remains basically unchanged, and the remaining oil still cannot be recovered, resulting in the overall recovery rate of this experimental scheme being much lower than that of Scheme 4 (the final recovery rate of Scheme 4 is 82.04%, and the final recovery rate of this scheme is 52.58%).

[0117] (8) For the 8th simulation experiment, the oil viscosity was 90 cP and the quartz sand diameter was about 0.125-0.25 mm. The experimental data of the scheme are shown in Tables 10 and Fig.12 .

[0118] Table 10 Experimental test results of oil viscosity 90cP (sand particle diameter 0.125-0.25mm)

[0119]

[0120] By comparing the experimental data with that of Scheme (3), it can be found that when the sand is fine, the water breakthrough time is earlier (Scheme 3 0.37HPV breakthrough, this scheme 0.14HPV breakthrough), and the recovery degree is lower when the outlet water content is 90% (Scheme 3 40.61%, this scheme 25.83%). It can also be found through the profile changes that the interface stability is worse when the sand is fine, the water channeling is more serious, the oil-water interface of the two profile observation windows is not symmetrical, and after the water content rises rapidly to about 80%, the oil stored on the other side of the profile is slowly displaced. After the top gas is injected, the gas-oil interface becomes more unstable, but a large amount of oil remaining on the other side of the gas injection section at the top is partially driven out, but the amount driven out is small, and the interface change is not obvious, resulting in a slow increase in the water content during the gas drive process and a low overall recovery rate (the final recovery rate of Scheme 3 is 58.03%, and the final recovery rate of this Scheme is 48.49%).

[0121] (9) The 9th simulation experiment, with variable water volume multiples and quartz sand diameter of about 0.125-0.25 mm, is shown in Tables 11 and Fig.13 .

[0122] Table 11. Experimental test results of 500 times water (sand particle diameter 0.125-0.25mm)

[0123]

[0124] By comparing the experimental data with that of Scheme (2), it can be found that when the sand is fine, the water breakthrough time is earlier, with Scheme (2) breaking through at 0.33 HPV and this scheme breaking through at 0.29 HPV. When the outlet water content is 90%, the recovery rate is low, with Scheme (2) at 52.76% and this scheme at 46.19%. Through the profile changes, it can be found that the interface stability is worse and the water channeling is more serious when the sand is fine. After the water breakthrough, the water content rises rapidly to about 70%. After the top gas is injected, the gas-oil interface of the fine sand is more unstable, the gas breakthrough is earlier, and the water content rises faster after the gas breakthrough. The overall recovery rate is low. The final recovery rate of Scheme (2) is 66.64%, and the final recovery rate of this scheme is 56.98%.

[0125] (10) The 10th simulation experiment, basic scheme, quartz sand diameter about 0.125-0.25mm scheme experimental data are shown in Table 12 and Fig.14 .

[0126] Table 12 Experimental test results of basic scheme (sand particle diameter 0.125-0.25mm)

[0127]

[0128] By comparing the experimental data with that of Scheme (1), it can be found that when the sand is fine, the water breakthrough time is earlier, Scheme (1) is 0.49HPV breakthrough, and this scheme is 0.35HPV breakthrough. When the outlet water content is 90%, the recovery rate is low, Scheme (1) is 56.57%, and this scheme is 46.34%. Through the change of the profile, it can be found that the interface stability is worse when the sand is fine, the water channeling is more serious, and the water content rises faster after the water breakthrough; after the top gas injection, the gas-oil interface of the fine sand is more unstable, the gas breakthrough is earlier, and the water content rises faster after the gas breakthrough. The overall recovery rate is low, and the final recovery rate of Scheme (1) is 65.16%, and the final recovery rate of this scheme is 57.18%.

[0129] (11) In the 11th simulation experiment, the gas injection rate was increased. The experimental data of three quartz sand mixing schemes (mixture of coarse sand, fine sand, and ultrafine sand less than or equal to 0.1D) are shown in Table 13.

[0130] Table 13. Experimental test results of increasing gas injection rate (mixing of three types of sand particles)

[0131]

[0132]

[0133] By comparing the experimental data of Scheme (5) and Scheme (6), it can be found that when the sand particles are mixed, the heterogeneity is stronger and the water breakthrough time is earlier. Scheme (6) is 0.49HPV breakthrough, Scheme (5) is 0.41HPV breakthrough, and this scheme is 0.16HPV breakthrough. When the outlet water content is 90%, the recovery degree is low, Scheme (6) is 59.55%, Scheme (5) is 50.03%, and this scheme is 33.96%. Through the changes in the profile, it can be found that the interface stability is worse in the mixed sand, the water breakthrough is more serious, and the water content rises rapidly after the water breaks through. After the gas is injected from the top, the mixed sand has a strong heterogeneity and the gas breaks through early. After the gas breaks through, the water content rises rapidly. The observation window of the two-dimensional profile does not clearly observe the change of the gas-oil interface. The gas goes directly from the injection well to the production well without obviously affecting the observation windows on both sides, resulting in a small decrease in the outlet water content, less oil produced, and a very low overall recovery rate, which is 78.92% for scheme (6), 58.17% for scheme (5), and 38.29% for this scheme.

[0134] (12) The experimental data of the 12th simulation experiment, basic scheme, and three quartz sand mixing schemes are shown in Table 14.

[0135] Table 14. Experimental test results of basic scheme (mixture of three types of sand)

[0136]

[0137]

[0138] By comparing the experimental data of Scheme (1) and Scheme (10), it can be found that when the sand particles are mixed, the heterogeneity is stronger and the water breakthrough time is earlier. Scheme (1) is 0.49HPV breakthrough, Scheme (10) is 0.35HPV breakthrough, and this scheme is 0.2HPV breakthrough. When the outlet water content is 90%, the recovery degree is low, Scheme (6) is 59.55%, Scheme (5) is 50.03%, and this scheme is 34.48%. Through the changes in the profile, it can be found that the interface stability is worse in the mixed sand, the water breakthrough is more serious, and the water content rises rapidly after the water breaks through. After the gas is injected from the top, the mixed sand has strong heterogeneity and the gas breaks through early. After the gas breaks through, the water content rises rapidly. The observation window of the two-dimensional profile does not clearly observe the change of the gas-oil interface. The gas goes directly from the injection well to the production well without obviously affecting the observation windows on both sides, resulting in less oil production. The overall recovery rate is very low, which is 65.16% for scheme (1), 57.18% for scheme (10), and 43.45% for this scheme.

[0139] The data collected from different experimental schemes are used to calculate the gravity number using formula (1), where N G is the gravity number; v is the seepage velocity, m / s; μ is the fluid viscosity, mPa·s; Δρ is the gas-oil density difference, g / cm 3 ; g is the acceleration due to gravity, m / s 2 ; k is the permeability, 10 -3 μm 2 ; C is the constant generated by unit conversion, C = 8.64 × 10 -5 ; α is the formation dip. The corresponding change relationship diagram of gravity number and gas drive recovery degree is drawn. There is a good positive correlation between gravity number and gas drive recovery degree, that is, the larger the gravity number, the higher the gas drive recovery degree and the more stable the oil-gas interface. At the same time, when the gravity number is greater than 0.5, the gas drive recovery degree increases from 43% to 57%, and when the gravity number is greater than 2.5, the gas drive recovery degree increases from 57% to 66%.

[0140] The data collected from different experimental schemes were used to calculate the capillary number using formula (2). A graph showing the relationship between the capillary number and the gas drive recovery degree was drawn. When the capillary number was less than 0.7×10 -4When the oil-gas interface is relatively stable, the recovery rate is high, and the maximum can reach 69.08%. With the increase of capillary number, the recovery rate decreases slightly, and the oil-gas interface gradually becomes unstable. Because the capillary number describes the balance between viscosity and capillary force, the larger the capillary number, the greater the viscosity and the smaller the capillary force, the easier it is for the oil and gas front to become unstable and form local fingering, which reduces the macro displacement efficiency. In addition, the capillary number is mainly affected by the interface seepage velocity. The greater the gas injection velocity, the greater the capillary number; the better the porosity and permeability conditions, the larger the capillary diameter, the smaller the interface capillary velocity, and the smaller the capillary number, the more conducive to stable interface seepage.

[0141] The data collected from different experimental schemes were used to calculate the Bond number using formula (3). The relationship between the Bond number and the gas drive recovery degree was plotted. Since the Bond number has a single variable parameter, it cannot evaluate the gas drive effect well. Combined with the numerical simulation results of the mechanism model, the corresponding Bond value was calculated. The results showed that the larger the Bond number, the higher the recovery rate, and the more conducive it is to implement gas cap gravity drive. When the Bond number reaches 9.21×10 3 When the oil recovery rate reaches 82.04%, the Bond number can also be used to characterize the oil-gas interface changes during gas cap gravity drive because the variable parameters considered are relatively single.

[0142] According to the five-element stable flooding coefficient formula (4):

[0143]

[0144] make The sensitive parameters in different experimental schemes were substituted into the calculated values ​​of the parameters of the five-element stable drive coefficient, and the relationship between the five-element stable drive coefficient and the gas drive recovery degree was drawn according to the five-element stable drive coefficient formula. When the five-element stable drive coefficient is ≥ 0, the interface stability is good, the recovery degree is greater than 50%, and the closer the evaluation coefficient is to 0, the higher the recovery degree is, which can reach up to 82.04%.

[0145] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A method for conducting an experiment using a gas injection gravity drive three-dimensional visual physical simulation device, characterized in that: The gas injection gravity drive three-dimensional visual physical simulation device includes a sample injection system, a reservoir simulation system, a production system and a monitoring system; The reservoir simulation system comprises a box, a multi-angle adjustment bracket, a saturation electrode and a bubble-type electronic angle measuring instrument, wherein the multi-angle adjustment bracket comprises an inclination adjustment mechanism arranged at the bottom of the box and bearings arranged at the left and right ends of the box; the inclination adjustment mechanism consists of a base and an arc-shaped bracket, the arc-shaped bracket opens upward, and the bottom of the arc-shaped bracket is mounted on the base in a manner that the left and right inclination angles can be adjusted; Specifically, a raised connecting piece is arranged on the upper surface of the base, and the bottom of the arc-shaped bracket is fixed to the connecting piece by screws; the connecting piece is two vertically arranged metal sheets, the bottom ends of the metal sheets are fixed to the base, and the two metal sheets are arranged in parallel; the bottom end of the arc-shaped bracket is installed in the gap between the two metal sheets, and the arc-shaped bracket is fixed to the two metal sheets by screws; a supporting plate is fixed to each of the two end surfaces of the arc-shaped bracket, and the bearings at the left and right ends of the box are fixed to the two supporting plates respectively; under the action of the bearing, the box can rotate 180° around the bearing, and the floating bubble type electronic angle measuring instrument is arranged on one of the supporting plates; visual sapphire windows are arranged on the front and back of the box, and the top of the box The top and bottom surfaces of the box are provided with detachable metal covers, and two parallel detachable filter plates are provided in the middle of the box body, the filter plates are parallel to the front surface of the box body, and the space between the two filter plates is filled with quartz sand required for the experiment; the metal covers on the top and bottom surfaces of the box body are provided with equidistant screw holes, each screw hole is provided with a reinforced metal screw, and a sealing gasket is provided between the metal cover plate and the box body; the saturation electrodes are provided with multiple groups and extend inwardly from the metal cover plate on the top surface of the box body to the inside of the box body, and at the same time maintain a sealed connection with the intersection of the metal cover plate on the top surface of the box body; the box body is also provided with oil and water injection ports, gas injection ports and liquid outlets; the entire reservoir simulation system is arranged inside the floor-standing oven; The sample injection system injects simulated oil and simulated edge and bottom water into the box through the oil and water injection port, and injects simulated gas into the box through the gas injection port; the sample injection system includes: a constant speed and constant pressure displacement pump, a simulated gas injection device, a simulated edge and bottom water device, a simulated oil device, and a back pressure constant pressure device, the simulated gas injection device, the simulated edge and bottom water device, the simulated oil device, and the back pressure constant pressure device are all connected to the constant speed and constant pressure displacement pump through pipelines and valves, the gas source device is connected to the simulated gas injection device through a three-way valve, and the back pressure constant pressure device is connected to the back pressure valve through a back pressure pressure sensor; The output system is connected to the liquid outlet and is used to measure the amount of oil, water and gas produced; the output system includes an oil-water metering device and a gas metering device, the oil-water metering device is connected to the liquid outlet of the box through a pipeline, and the gas metering device is connected to the oil-water metering device through a pipeline, and the oil, gas and water are measured by a measuring cylinder and a drainage and gas collecting device to collect and measure oil, gas and water; The monitoring system includes a back pressure sensor, an inlet pressure sensor, an outlet pressure sensor, a pressure monitoring system and a real-time video recording device, and the back pressure sensor, the inlet pressure sensor and the outlet pressure sensor are all connected to the pressure monitoring system; The steps of the experimental method are as follows: S1. Prepare simulated oil and simulated formation water, dye the simulated formation water and simulated oil with methyl blue and Sudan red respectively; the experimental gas is high-pressure nitrogen; fill the box of the reservoir simulation system with quartz sand, vibrate and compact it, and test whether the permeability meets the order of magnitude designed in the experimental scheme. If not, adjust the size standard of quartz sand and refill it; S2. Connect the experimental device and check the tightness of the experimental device; then evacuate the experimental device and fully saturate it with simulated oil to the formation pressure of the simulated experiment, and record the saturated oil volume; S3, the oven temperature is raised to the target temperature of the simulation experiment, and the back pressure of the experimental device is adjusted to the target pressure of the experiment; after changing the inclination angle of the profile model to the angle required by different experimental schemes, a constant pressure and constant speed displacement pump is used to simulate the water-to-oil process of strong edge water; the injection speed required by different experimental schemes is adjusted to represent the energy of the edge water body of different reservoirs, and the injected water volume is recorded in real time. The oil production well is simulated through the liquid outlet on the upper part of the box, the water volume and oil volume driven out are recorded, the saturation is recorded, the outlet water content is calculated, and the interface changes are recorded through a real-time video recording device; S4. When the water content at the upper liquid outlet of the tank reaches 90%, keep the water injection at the bottom unchanged and start injecting nitrogen at the top. Record the amount of water and gas injected, the amount of gas, water and oil produced, the saturation, calculate the outlet water content, and record the interface changes through a real-time video recording device. S5. When the water content at the outlet reaches above 98%, stop the experiment and complete the gas-assisted gravity drive experiment.

2. The method for conducting experiments using a three-dimensional visual physical simulation device for gas injection gravity drive according to claim 1, characterized in that: There are two arc-shaped brackets, which are arranged parallel to each other. Each arc-shaped bracket is connected to the base through two connecting pieces. The two end surfaces of the two arc-shaped brackets on the same side are fixed to the support plate at the same time.

3. The method for conducting experiments using a three-dimensional visual physical simulation device for gas injection gravity drive according to claim 1, characterized in that: The step S6 is also included, data processing, which is as follows: (1) According to the data obtained from different experimental schemes, the gravity number is calculated using the following formula: ， In the formula, N G is the gravity number; is the seepage velocity, m / s; μ is the fluid viscosity, mPa·s; Δρ is the gas-oil density difference, g / cm 3 ; g is the acceleration due to gravity, m / s 2 ; k is the permeability, 10 -3 μm 2 ; C is the constant generated by unit conversion, C=8.64×10 -5 ; is the formation dip; Draw a graph showing the relationship between the gravity number and the gas drive recovery degree; (2) Based on the data obtained from different experimental schemes, the capillary number is calculated using the following formula: In the formula, N C is the capillary number; is the seepage velocity, m / s; μ is the fluid viscosity, mPa·s; σ is the interfacial tension, N / m; is the formation dip; Draw a graph showing the relationship between the number of capillary tubes and the degree of gas drive recovery; (3) Based on the data obtained from different experimental schemes, the Bond number is calculated using the following formula: In the formula, N b is the Bond number; σ is the interfacial tension, N / m; Δρ is the gas-oil density difference, g / cm 3 ; g is the acceleration due to gravity, m / s 2 ; K is the permeability, 10 -3 μm 2 ; ϕ is the porosity; is the formation dip; Draw a graph showing the relationship between the Bond number and the gas drive recovery degree; (4) Based on the five-element stable drive coefficient formula: Where k is the permeability, 10 -3 μm 2 ; θ is the formation dip; μ is the fluid viscosity, mPa·s; τ is the water volume multiple; is the seepage velocity, m / s; Substitute the sensitive parameters in different experimental schemes to obtain the calculated values ​​of the parameters of the five-element stable drive coefficient, and draw the relationship diagram between the five-element stable drive coefficient and the gas drive recovery degree according to the five-element stable drive coefficient formula; (5) Calculate the oil recovery efficiency E using the following formula: D : ， In the formula, Q O The amount of oil displaced during the experiment, ml; S O is the oil saturation; V is the volume of the reservoir simulation system, cm 3 ; φ is the porosity of the box after filling with sand; using E D Evaluating the sweep efficiency of the swept area of ​​the gravity stability profile can more accurately evaluate the mobilization capacity of different injection and production systems on reservoir pores.

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