An experimental apparatus and method for foam generation conditions and transport characteristics

Abstract

The application provides an experimental device and method for foam generation conditions and migration characteristics, which comprises a thermostat, a visual experiment device, a back pressure system, a gas-liquid separator, a liquid collecting bottle and a gas-liquid supply system; the gas-liquid supply system is connected with the lower end inlet of the visual experiment device, the upper end outlet of the visual experiment device is connected with the back pressure system, the back pressure system is connected with the gas-liquid separator, a gas flow meter is arranged on the upper end gas outlet pipeline of the gas-liquid separator, and the liquid collecting bottle is arranged at the lower end of the gas-liquid separator; and the visual experiment device is arranged in the thermostat. In the application, transparent glass microbeads (0.1-4mm) with different mesh numbers are introduced to simulate porous medium reservoirs. Through the visual sand filling pipe, the change of the foam is monitored and recorded by using an endoscope under high pressure and high temperature conditions to describe the seepage characteristics and rules of the foam in the pore medium, and meanwhile, when applied to chemical oil displacement, the process and effect of the chemical oil displacement can be directly observed and evaluated.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical application field of preventing gas channeling in oil well and timely treating after gas channeling, and particularly relates to an experimental device and method for foam generation conditions and migration characteristics. BACKGROUND

[0002] For low-permeability oilfields, the effect of gas injection development is better than that of water injection, but in the process of gas injection displacement, due to the heterogeneity of the core, with the extension of injection time and the increase of injection pore volume multiple, the front part of the injected gas will form a channeling channel along the high-permeability layer of the core, and the injected gas will break through quickly to form gas channeling.

[0003] In order to inhibit the occurrence of gas channeling in the process of air injection in low-permeability reservoirs and improve the efficiency of air injection, it is necessary to use a foam system to change the mobility of the gas and reduce the gas permeability in the process of gas injection development, so as to effectively delay the gas breakthrough time at the outlet and improve the oil displacement efficiency. However, the existing foam performance and parameter evaluation all use stirring method or airflow method in non-porous medium, which is different from the foaming conditions of gas and water in actual formation porous medium, so that the performance parameters and indexes of the foaming agent and its foam system determined in the laboratory cannot meet the requirements of improving the recovery efficiency.

[0004] At present, most of the foam performance test experiments use mechanical methods to generate foam, and observe the change of the foam growth process and the decay process of the foam. For air foam with low viscosity, stirring method, airflow method, pouring method and oscillation method are generally used. Such foam generated only in non-porous medium is seriously inconsistent with the foam generated in real formation and its performance, so that the properties of the foaming agent and its foam system determined in the laboratory cannot meet the requirements of foam performance parameters and indexes required for improving the recovery efficiency.

[0005] And the previous literature on the experimental study of the plugging performance of foam is mostly carried out under the condition of no back pressure or back pressure much lower than the actual reservoir pressure. In this experiment, the back pressure valve is used to simulate the actual reservoir pressure, and the factors affecting the plugging performance and stability of the foam in the porous medium are preliminarily experimentally studied. SUMMARY

[0006] In order to overcome the problem that the properties of the foaming agent and its foam system determined in the laboratory cannot meet the requirements of foam performance parameters and indexes required for improving the recovery efficiency, the present application provides an experimental device and method for foam generation conditions and migration characteristics, which makes the performance parameters and indexes of the foaming agent and its foam system determined in the laboratory meet the requirements required for improving the recovery efficiency, obtains the generation conditions and migration characteristics of the air foam system under the condition of porous medium, determines the foaming performance and stability mechanism of the foam in the porous medium and its influencing factors, and provides guidance for field channeling plugging.

[0007] The technical scheme adopted by the present application is as follows:

[0008] An experimental device for foam generation conditions and migration characteristics comprises a thermostat, a visual experimental device, a back pressure system, a gas-liquid separator, a liquid collecting bottle and a gas-liquid supply system; the gas-liquid supply system is connected with the lower end inlet of the visual experimental device, the upper end outlet of the visual experimental device is connected with the back pressure system, the back pressure system is connected with the gas-liquid separator, a gas flow meter is arranged on the upper end gas outlet pipeline of the gas-liquid separator, and the liquid collecting bottle is arranged at the lower end of the gas-liquid separator; and the visual experimental device is arranged in the thermostat.

[0009] The visual experimental device comprises a support, a shell, a key groove and a sand filling pipe; the shell is arranged on the support, the shell is a hollow cuboid shell, the sand filling pipe is arranged at the center of the shell along a central axis, a key groove is formed on one side surface of the shell, and a glass is sealingly arranged in the key groove.

[0010] An endoscope is arranged in the visual experimental device.

[0011] The sand filling pipe is a high-pressure visual sand filling pipe, and the high pressure is not less than 40 MPa; and the sand filling pipe is a hollow transparent pipe.

[0012] Transparent glass microbeads are filled in the sand filling pipe; and the particle size of the glass microbeads is 0.1-4 mm.

[0013] The back pressure system comprises a back pressure valve and a hand pump; the back pressure valve is connected with the hand pump, and the back pressure valve is arranged on the gas-liquid separator inlet pipeline, and a pressure sensor is further arranged on the pipeline.

[0014] The gas-liquid supply system comprises a gas source, a gas booster pump, a high-pressure storage tank, a gas pressure regulating valve, a piston container and a liquid storage tank; the gas source is connected with the high-pressure storage tank through the gas booster pump, the high-pressure storage tank is connected with the piston container through the gas pressure regulating valve, the outlet pipeline of the piston container is connected with the visual experimental device in the thermostat, and a pressure sensor is arranged on the outlet pipeline; and the liquid storage tank is connected with the piston container.

[0015] The liquid stored in the liquid storage tank is foam or gel.

[0016] An experimental method for foam generation conditions and migration characteristics is provided, and the specific steps are as follows:

[0017] Step one, transparent glass microbeads are filled in the sand filling pipe in the visual experimental device, a filling model is established, and a porous medium reservoir is simulated;

[0018] Step two, liquid is first injected into the sand filling pipe, and then gas is injected for foaming through the gas-liquid supply system;

[0019] Step three, the change of the liquid foam is monitored and recorded by the endoscope to describe the percolation characteristics and rules of the foam in the porous medium;

[0020] Step four, the base porosity and permeability parameters of the filling model are measured, the average pore radius parameter of the filling model is obtained by the Korsunov equation, and the influence of the average pore radius on the foaming volume of the foaming agent is judged.

[0021] The Korsunov equation is as follows:

[0022]

[0023] In the formula, r is the average pore throat radius of the core, μm;

[0024] K is the core permeability, 10 -3 μm 2 ;

[0025] φ is the core porosity, dimensionless.

[0026] The beneficial effects of the present application are as follows:

[0027] In the present application, the endoscope is arranged in the visualized experimental device, and the endoscope can monitor and record the change of the foam to describe the percolation characteristics and rules of the foam in the porous medium.

[0028] In the present application, the shell of the visualized experimental device is made of stainless steel, and the glass at the key groove is made of aviation material, so that the visualized experimental device is pressure-resistant and high-temperature-resistant as a whole.

[0029] In the present application, the situation in the visualized experimental device can be directly observed through the glass at the key groove. In the present application, the height of the bracket is determined according to the height of the operator, so that the operator does not need to bend too low when observing, and the operator is protected. Similarly, other components are also placed on the corresponding brackets according to the requirements, so as to ensure the safety and convenience of operation.

[0030] In the present application, different mesh transparent glass microbeads (0.1-4mm) are introduced to simulate the porous medium reservoir. Through the visualized sand filling pipe, the change of the foam is monitored and recorded by the endoscope under high pressure and high temperature conditions to describe the percolation characteristics and rules of the foam in the porous medium, and meanwhile, when applied to chemical oil displacement, the process and effect of the chemical oil displacement can be directly observed and evaluated.

[0031] In the present application, the average pore radius parameter of the filling model is obtained by the Korsunov equation, and the influence of the average pore radius on the foaming volume of the foaming agent is judged.

[0032] The present application will be further described below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 Foam migration pattern in large particle size (1-4mm) porous medium.

[0034] Figure 2 Foam migration pattern in small particle size (0.1-0.44mm) porous medium.

[0035] Figure 3 Effect of permeability on the foaming volume of C1 foaming agent.

[0036] Figure 4 Effect of permeability on the foaming volume of C3 foaming agent.

[0037] Figure 5 Effect of pore size on the foaming volume of C1 foaming agent.

[0038] Figure 6 Effect of pore size on the foaming volume of C3 foaming agent.

[0039] Figure 7 Structure schematic diagram of the present application.

[0040] Figure 8 Structure schematic diagram of the visualization experimental device.

[0041] In the figure, the reference signs are: 1, gas source; 2, gas booster pump; 3, high-pressure tank; 4, gas pressure regulating valve; 5, piston container; 6, pressure sensor; 7, constant temperature box; 8, visualization experimental device; 9, back pressure system; 10, gas-liquid separator; 11, gas flow meter; 12, liquid collection bottle; 13, electronic balance; 14, liquid storage tank;

[0042] 801, support; 802, shell; 803, key groove; 804, sand filling pipe;

[0043] 901, back pressure valve; 902, hand pump. DETAILED DESCRIPTION

[0044] Example 1:

[0045] In order to overcome the problem that the properties of the foaming agent and the foam system determined in the laboratory cannot meet the required foam performance parameters and indexes for improving the recovery rate, the present application provides a foam generation condition and migration characteristic experimental device and method as shown in Figures 1-8 The present application makes the performance parameters and indexes of the foaming agent and the foam system determined in the laboratory meet the requirements for improving the recovery rate, obtains the generation condition and migration characteristic of the air foam system under the condition of porous medium, determines the mechanism and influencing factors of the foaming performance and stability of the foam in the porous medium, and provides guidance for field channeling blocking.

[0046] An experimental device for foam generation condition and migration characteristics, comprising a thermostat 7, a visualized experimental device 8, a back pressure system 9, a gas-liquid separator 10, a liquid collecting bottle 12 and a gas-liquid supply system; the gas-liquid supply system is connected with the lower end inlet of the visualized experimental device 8, the upper end outlet of the visualized experimental device 8 is connected with the back pressure system 9, the back pressure system 9 is connected with the gas-liquid separator 10, a gas flow meter 11 is arranged on the upper end gas outlet pipeline of the gas-liquid separator 10, and the liquid collecting bottle 12 is arranged at the lower end of the gas-liquid separator 10; and the visualized experimental device 8 is arranged in the thermostat 7.

[0047] In the present application, the thermostat 7 can be adjusted to the required temperature, and the required temperature is set. In the present application, the thermostat 7 is not the prior art, and further description will not be made in the present application.

[0048] The visualized model in the prior research is mostly based on normal temperature and pressure or high temperature (60℃), and the key of the present application lies in the high-temperature and high-pressure visualized model (40MPa pressure resistance, 300℃ temperature resistance), and the high-precision endoscope is used to monitor the foam flow and change in the model.

[0049] In the present application, the glass microspheres are filled in the visualized experimental device 8, then the liquid and gas are input into the sand filling pipe 804 filled with the glass microspheres through the gas-liquid supply system, and the gas is injected through the gradually decreasing constant pressure. In the present application, the transparent glass microbeads (0.1-4mm) of different mesh numbers are filled in the visualized experimental device 8, the filling model is established, and the porous medium reservoir is simulated. The back pressure system 9 is established according to the original pressure of the oil reservoir, and the back pressure established by the back pressure system 9 is set according to the actual demand. In the embodiment, the back pressure is preferably 12.5MPa. The gas is injected into the transparent filling model at a constant pressure to foam, the pressure is gradually decreased, the pressure gradient is set in advance according to the demand, and the pressure gradient is preferably 5MPa / cm in the present application.

[0050] In the present application, as shown in Figure 7 The gas-liquid supply system injects the required liquid and gas into the visualized experimental device 8, the liquid foam is foamed in the visualized experimental device 8, after the foaming is completed, the gas-liquid mixture enters the back pressure system 9, the gas-liquid mixture from the back pressure system 9 enters the gas-liquid separator 10, the gas-liquid separation is carried out, the separated gas is metered through the gas meter 11, the separated liquid enters the liquid collecting bottle 12, and the electronic balance is used for weighing and metering, so that the gas-liquid ratio is obtained, which provides the basis for the gas channeling prevention and treatment.

[0051] In this invention, the changes in foam within the visualization experimental device 8 are monitored and recorded using an endoscope to describe the seepage characteristics and patterns of foam in porous media. This method can also be applied to chemical flooding, allowing the chemical flooding process to be observed and the effects to be evaluated intuitively through the visualization experimental device 8 and the endoscope.

[0052] This invention enables the performance parameters and indicators of foaming agents and their foam systems determined in the laboratory to meet the requirements for improving oil recovery. It obtains the generation conditions and transport characteristics of air foam systems under porous media conditions, determines the mechanism and influencing factors of foam foaming performance and stability in porous media, and provides guidance for field sealing.

[0053] Example 2:

[0054] Based on Embodiment 1, in this embodiment, preferably, the visualization experimental device 8 includes a support 801, a housing 802, a keyway 803, and a sand-filling tube 804. The housing 802 is mounted on the support 801 and is a hollow cuboid housing. The sand-filling tube 804 is located at the center of the housing 802 along the central axis. A keyway 803 is formed on one side surface of the housing 802, and glass is sealed inside the keyway 803.

[0055] Preferably, the visualization experimental device 8 is equipped with an endoscope.

[0056] Preferably, the sand filling pipe 804 is a high-pressure visual sand filling pipe with a high pressure of not less than 40 MPa; the sand filling pipe 804 is a hollow transparent pipe.

[0057] In this invention, such as Figure 8 As shown, the housing 802 is made of stainless steel, and the glass installed at the keyway 803 on the housing 802 is made of aviation glass material, which has the functions of high temperature resistance and pressure resistance. This ensures that the operator can have a direct view of the various conditions inside the sand-filled pipe 804 through the glass at this location.

[0058] In this invention, the keyway 803 has a row of bolts and nuts at both ends. The housing 802 can be two symmetrical halves, which are fixedly connected as one piece by bolts and nuts. Valves are provided at both the top and bottom ends of the housing 802. The left and right ends of the housing 802 are mounted on the bracket 801. In this invention, the bracket 801 is a trapezoidal frame with a larger bottom end and a smaller top end. The bottom end of the trapezoidal frame is equipped with casters.

[0059] In this invention, the visualization experimental device 8 can be set horizontally or vertically.

[0060] Preferably, the sand-filled tube 804 is filled with transparent glass microspheres; the particle size of the glass microspheres is 0.1-4 mm.

[0061] Preferably, the back pressure system 9 comprises a back pressure valve 901 and a hand pump 902, the back pressure valve 901 is connected with the hand pump 902, the back pressure valve 901 is arranged on the inlet pipeline of the gas-liquid separator 10, and the pipeline is also provided with the pressure sensor 6.

[0062] Preferably, the gas-liquid supply system comprises a gas source 1, a gas booster pump 2, a high-pressure tank 3, a gas pressure regulating valve 4, a piston container 5 and a liquid storage tank 14, the gas source 1 is connected with the high-pressure tank 3 through the gas booster pump 2, the high-pressure tank 3 is connected with the piston container 5 through the gas pressure regulating valve 4, the outlet pipeline of the piston container 5 is connected with the visual experiment device 8 in the thermostat 7, and the outlet pipeline is provided with the pressure sensor 6; and the liquid storage tank 14 is connected with the piston container 5.

[0063] In the application, the piston container 5 is a prior art, and will not be further described in the application. The piston container 5 comprises a plurality of parallelly arranged strip-shaped containers, and the gas and the liquid to be injected can be injected from different strip-shaped containers or sequentially injected from the same strip-shaped container. The upper end and the lower end of the strip-shaped container are provided with interfaces, the interfaces are selected according to requirements, and the gas and the liquid can be quickly and effectively injected. The piston container 5 can realize injection of different component segments and gelation in the reservoir.

[0064] In the application, the pressure sensor 6 comprises a gas pressure sensor and a liquid pressure sensor 6, and the pressure sensor 6 is selected and arranged at a required position according to requirements.

[0065] Preferably, the liquid stored in the liquid storage tank 14 is foam or gel.

[0066] An experimental method for foam generation conditions and migration characteristics, and the specific steps are:

[0067] Step one, transparent glass beads are filled in the sand filling pipe 804 in the visual experiment device 8 to establish a filling model and simulate a porous medium reservoir;

[0068] Step two, the liquid is first injected into the sand filling pipe 804, and then the gas is injected to foam through the gas-liquid supply system;

[0069] Step three, the change of the liquid foam is monitored and recorded through the endoscope to describe the seepage characteristics and rules of the foam in the pore medium;

[0070] Step four, the basic porosity and permeability parameters of the filling model are measured, the average pore radius parameter of the filling model is obtained through the high-cali equation, and the influence of the average pore radius on the foaming volume of the foaming agent is judged.

[0071] The high-cali equation is as follows:

[0072]

[0073] Where: r - average pore throat radius of the core, μm;

[0074] K - Core permeability, 10 -3 μm 2 ;

[0075] φ - Core porosity, dimensionless.

[0076] In this invention, the process of conducting experiments on foam generation conditions and transport characteristics is as follows:

[0077] Gas from gas source 1 is pumped by gas booster pump 2 (0-50MPa) to gas pressure regulating valve 4 (0-50MPa pressure control of inlet and outlet via pressure diaphragm). Liquid (foam and gel) then enters piston container 5 through six-way valve, and gas enters sand filling pipe 6 through six-way valve. Gas and liquid (foam and gel) are mixed in high-pressure visual sand filling pipe, allowing for direct observation of foam changes and chemical oil displacement process, with real-time dynamic monitoring. A precise backpressure system 9 (hand-cranked pump pressurization 0-40MPa) is used to prevent gas channeling. Finally, gas and liquid are separated by gas-liquid separator 10. Gas is measured by gas flow meter 11, and liquid enters collection bottle 12 and is measured by electronic balance 13.

[0078] This invention utilizes an endoscope to monitor and record changes in foam to describe the seepage characteristics and patterns of foam in porous media. Figure 1 , Figure 2 ), and observe the chemical flooding process to visually evaluate the effect.

[0079] This invention uses quantitative methods to analyze the effects of permeability on the foaming volume of foaming agents and the effects of average pore radius on the foaming volume of foaming agents.

[0080] This invention uses comparative experiments on C1 and C3 foaming agents to specifically illustrate the experiments in the following four aspects: Transparent glass microspheres (0.1-4 mm) of different mesh sizes are filled into the experimental model to simulate a porous reservoir. The back pressure at the model outlet is established based on the original reservoir pressure; the back pressure for C1 is 9.5 MPa, and for C3 it is 12.5 MPa. Gas is injected into the transparent filled model at a constant pressure for foaming, with a preferred pressure decrease gradient of 5 MPa / cm. Endoscopic monitoring and recording of foam changes are used to describe the seepage characteristics and patterns of foam in the porous medium.

[0081] I. Characteristics of Foam Flow in Porous Media

[0082] Depend on Figure 1It can be seen that when the pore throat size is greater than the bubble diameter, the single bubble can directly pass through the pore throat without deformation caused by contact with the pore wall, and the stability is good, but the plugging capacity is poor; when the number of bubbles increases, multiple bubbles are stacked and misaligned through the pore throat, at this time, the bubbles interfere with each other and deform due to mutual extrusion; at the same time, the bubbles coalesce, resulting in an increase in bubble diameter, reducing the stability.

[0083] By Figure 2 It can be seen that when the pore throat size is greater than the bubble diameter, the single bubble can directly pass through the pore throat without deformation caused by contact with the pore wall, and the stability is good, but the plugging capacity is poor; when the number of bubbles increases, multiple bubbles are stacked and misaligned through the pore throat, at this time, the bubbles interfere with each other and deform due to mutual extrusion; at the same time, the bubbles coalesce, resulting in an increase in bubble diameter, reducing the stability.

[0084] When the pore throat size and the bubble diameter are similar, the bubble deforms less when passing through the pore throat. The pressure from the throat is small and not enough to cause the bubble to rupture, at this time the foam stability is good and has certain plugging capacity.

[0085] In the pore medium, the bubbles will produce dynamic interference between them during continuous migration, especially the coalescence of bubbles, which is the manifestation of the instability of the bubbles. The extrusion of bubbles to each other and the restriction of the pore throat size cause the deformation of the bubbles, interfere with the drainage speed of the liquid film and the distribution of the liquid film strength, and make the bubbles change to instability.

[0086] For the pores intersecting each other, the throats at the tips meet during the movement of the bubbles, the collision between the liquid films causes the gas diffusion and the liquid film drainage, and the bubbles continue to merge. Moreover, the bubbles behind are still continuously injected, and the pressure from the bubbles behind is also increasing, and the propelling effect is continuously strengthened, causing the bubbles to further deform, and the liquid film at the contact between the two extruded bubbles continuously thins, accelerating the merging of the bubbles.

[0087] For the channel-type pore throat, the bubble must be extruded by the pore throat when passing through the pore throat because the bubble diameter is much larger than the pore throat size. When the pressure on the liquid film exceeds the bearing limit, the bubble ruptures and divides into multiple small bubbles. Through the analysis of multiple sets of experimental data, in the channel-type throat, the foam has a certain regenerative property, and the regenerative mechanism is the necking separation caused by the extrusion of the pore throat. The particle size of the foam regenerated by necking separation is much smaller than the pore throat size, which is beneficial to enhance the stability of the foam.

[0088] II. The influence of foaming pressure difference on plugging effect

[0089] Foam is a kind of unstable fluid, foam breaks and generates new foam when it moves in porous media. Due to the density difference between gas and liquid, gas phase will automatically rise, while liquid phase will descend under the action of gravity, so there is a certain degree of difference in the vertical distribution of foam. Due to this difference, the plugging efficiency of foam in the horizontal filling pipe is lower than that of the vertical filling pipe. As can be seen from Table 1, the greater the injection pressure difference, the higher the injection speed, and the higher the plugging efficiency of the foam generated.

[0090] Table 1 Influence of foaming pressure difference on plugging effect

[0091]

[0092]

[0093] At the same time, it can also be found from the experimental phenomena that the plugging pressure difference generated by the foam in the filling pipe without back pressure is greater than that generated by the foam with back pressure. In addition, it can also be seen from the experimental phenomena that higher injection speed can make the plugging pressure generated by the foam higher. This is because with the increase of the foam generation environment pressure, the decrease of the plugging pressure difference is due to the result of gas dissolving into the liquid phase. When the foam quality is certain, the greater the pressure, the smaller the foam radius, so the foam volume becomes smaller, and finally the foam is more easily through the pores and throats in the porous medium, weakening the resistance effect of the foam. Therefore, the evaluation experiment of the plugging performance of the foam needs to be carried out under the condition of simulating the actual reservoir pressure.

[0094] Three, the influence of porous media on the foaming performance of foaming agent

[0095] The above experiment can only describe the foaming agent foam flow rule and phenomenon in the image with a qualitative method. In order to better explain the experimental rule, some improvements are made to the model. The basic porosity and permeability parameters of the filling model are measured, and then the average pore radius parameters of the filling model are calculated by using the high zhen equation: the influence of permeability on the foaming volume of foaming agent is analyzed by using a quantitative method, and the influence of average pore radius on the foaming volume of foaming agent is analyzed.

[0096] Four, the influence of permeability on the foaming volume of foaming agent:

[0097] By filling glass beads of different mesh in the visualization model, the reservoirs with different pore size, pore throat type and permeability are simulated, and the foaming performance and foam parameters under different porous media are studied. The experimental results are shown in Figure 3 、 Figure 4 .

[0098] From Figure 3 it can be seen that the foaming volume of C1 foaming agent decreases with the increase of permeability. From Figure 4It can be seen that the foaming volume of C3 foaming agent decreases with the increase of permeability.

[0099] The influence of average pore throat radius on the foaming volume of foaming agent is shown in the following table: Figure 5 It can be seen that the foaming volume of C1 foaming agent decreases with the increase of average pore throat radius.

[0100] The influence of average pore radius on the foaming volume of foaming agent is shown in the following table: Figure 6 It can be seen that the foaming volume of C3 foaming agent decreases with the increase of average pore radius.

[0101] From the experimental results, it can be seen that the foam has different characteristics in different size pores:

[0102] (1) When the pore throat size is larger than the bubble diameter, the single bubble directly passes through, and multiple bubbles migrate in a side-by-side staggered manner, the bubbles deform and coalesce, the bubble diameter increases, and the stability becomes poor.

[0103] (2) When the pore throat size is similar to the bubble diameter, the deformation of the foam passing through the pore medium is small, and the pressure from the pore throat is not enough to cause the liquid film to break, coalesce and regenerate, and the stability is good.

[0104] (3) When the pore throat size is smaller than the bubble diameter, the bubble is deformed by extrusion, and when the pore throat pressure exceeds the critical pressure that the liquid film can withstand, the bubble breaks and new bubbles are generated.

[0105] (4) Under the condition of no medium, the concentration of foaming agent in the foam liquid film shows a gradual increasing trend from top to bottom, and the thickness of the liquid film increases with time. The difference in the concentration distribution of the foaming agent in the liquid film increases accordingly, and the Marangoni effect gradually increases, which is beneficial to improve the stability of the foam liquid film.

[0106] (5) From the high-pressure visualization experiment phenomenon, it can be seen that higher injection speed can make the plugging pressure generated by the foam higher. The evaluation experiment of the plugging performance of the foam needs to be carried out under the condition of simulating the actual reservoir pressure.

[0107] In the present application, the situation in the visual experiment device 8 can be directly observed through the glass at the key groove 803. In the present application, the height of the support 801 is determined according to the height of the operator, so that the operator does not need to bend down too low when observing, and the operator is protected. Similarly, other components are also placed on the corresponding supports according to the requirements, to ensure the safety and convenience of operation.

[0108] In the present application, different mesh transparent glass microbeads (0.1-4mm) are introduced to simulate porous medium reservoir. Through visual sand filling pipe, the change of foam is monitored and recorded by endoscope under high pressure and high temperature conditions to describe the percolation characteristics and rules of foam in porous medium. Meanwhile, when applied to chemical oil displacement, the process and effect of chemical oil displacement can be directly observed and evaluated.

[0109] The above examples are only illustrative of the present application and do not constitute a limitation on the protection scope of the present application. Any design identical or similar to the present application falls within the protection scope of the present application. The device structure and method steps not described in detail in the present application are prior art, and will not be further described in the present application.

Claims

1. An experimental method for determining the foam generation conditions and transport characteristics, characterized in that: The experimental device for foam generation condition and migration characteristics includes a constant temperature box (7), a visual experimental device (8), a back pressure system (9), a gas-liquid separator (10), a liquid collecting bottle (12) and a gas-liquid supply system; the gas-liquid supply system is connected with the lower end inlet of the visual experimental device (8), the upper end outlet of the visual experimental device (8) is connected with the back pressure system (9), the back pressure system (9) is connected with the gas-liquid separator (10), a gas flow meter (11) is arranged on the upper end gas outlet pipeline of the gas-liquid separator (10), and the liquid collecting bottle (12) is arranged at the lower end of the gas-liquid separator (10); the visual experimental device (8) is arranged in the constant temperature box (7); an endoscope is arranged in the visual experimental device (8); the visual experimental device (8) includes a support (801), a shell (802), a key groove (803) and a sand filling pipe (804); the shell (802) is arranged on the support (801); the shell (802) is a hollow cuboid shell; the sand filling pipe (804) is arranged at the center of the shell (802) along a central axis; a key groove (803) is formed in one side surface of the shell (802), and a glass is sealingly arranged in the key groove (803); the sand filling pipe (804) is a high-pressure visual sand filling pipe, and the high pressure is not less than 40 MPa; the sand filling pipe (804) is a hollow transparent pipe; the visual experimental device (8) is filled with glass microspheres, then liquid and gas are input into the sand filling pipe (804) filled with the glass microspheres through the gas-liquid supply system, and the gas is injected through a gradually decreasing constant pressure; the change of the foam is monitored and recorded through the endoscope to describe the seepage characteristics and rules of the foam in the pore medium and to observe the chemical oil displacement process; the glass arranged in the key groove (803) of the shell (802) is an aviation glass material. The experimental method for foam generation condition and migration characteristics includes the following steps: Step one, the sand filling pipe (804) in the visual experimental device (8) is filled with transparent glass microbeads to establish a filling model to simulate a porous medium reservoir; Step two, liquid is first injected into the sand filling pipe (804) through the gas-liquid supply system, and then gas is injected to foam; Step three, the change of the liquid foam is monitored and recorded through the endoscope to describe the seepage characteristics and rules of the foam in the pore medium; the high-temperature high-pressure visual model can withstand a pressure of 40 MPa and a temperature of 300 DEG C; the high-precision endoscope is used to monitor the foam flow and change in the model; Step four, the basic porosity and permeability parameters of the filling model are measured, the average pore radius parameter of the filling model is obtained through the high-precision equation, and the influence of the average pore radius on the foaming volume of the foaming agent is judged.

2. An experimental method for determining foam generation conditions and transport characteristics according to claim 1, characterized in that: The sand filling pipe (804) is filled with transparent glass microbeads; the particle size of the glass microbeads is 0.1-4 mm.

3. A method of experimentally determining foam generation conditions and transport characteristics according to claim 1, characterized in that: The back pressure system (9) comprises a back pressure valve (901) and a hand pump (902), the back pressure valve (901) is connected with the hand pump (902), the back pressure valve (901) is arranged on the inlet pipeline of the gas-liquid separator (10), and a pressure sensor (6) is arranged on the pipeline.

4. The method of claim 1, wherein: The gas-liquid system comprises a gas source (1), a gas booster pump (2), a high-pressure storage tank (3), a gas pressure regulating valve (4), a piston container (5) and a liquid storage tank (14), the gas source (1) is connected with the high-pressure storage tank (3) through the gas booster pump (2), the high-pressure storage tank (3) is connected with the piston container (5) through the gas pressure regulating valve (4), the outlet pipeline of the piston container (5) is connected with a visual experiment device (8) in a thermostat (7), and a pressure sensor (6) is arranged on the outlet pipeline; and the liquid storage tank (14) is connected with the piston container (5).

5. A method of experimentally determining foam generation conditions and migration characteristics according to claim 4, characterized in that: The liquid stored in the liquid storage tank (14) is foam or gel.

6. The method of claim 1, wherein: The high capillary equation is as follows: In the formula, r represents the average pore throat radius of the core, μm; φ represents the core porosity, dimensionless. K - Core permeability, 10 -3 μm 2 ; In the formula, r represents the average pore throat radius of the core, μm; φ represents the core porosity, dimensionless.

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