Microphysical model, experimental device and method for simulating bottom water reservoirs

Abstract

The present invention discloses a microphysical model, experimental device, and method for simulating bottom-water reservoirs. The microphysical model is made of a transparent material. The microphysical model includes an oil-bearing characteristic area and a bottom-water characteristic area. The oil-bearing characteristic area and the bottom-water characteristic area are located in the same plane, arranged adjacent to each other, and interconnected. A first injection channel is provided at the end of the bottom-water characteristic area away from the oil-bearing characteristic area, an output channel is provided at the end of the oil-bearing characteristic area away from the bottom-water characteristic area, and second and third injection channels are provided on either side of the oil-bearing characteristic area. The present invention can simulate the development process of strong bottom-water reservoirs under high-temperature and high-pressure conditions and clarify the mechanisms for enhancing oil recovery in bottom-water reservoirs, such as gas flooding and chemical flooding.

Description

Technical Field

[0001] The present invention belongs to the technical field of petroleum development experiments, and more specifically, relates to a microscopic physical model, an experimental device and a method for simulating bottom water reservoirs. Background Art

[0002] Bottom-water sandstone reservoirs are characterized by abundant natural energy, large water bodies, and a high production rate. Oilfields primarily rely on natural energy development. In the middle and late stages of the reservoir, bottom-water coning is evident, with rapid increases in water cut. Oil wells generally have high water cuts, low recovery rates, and great development potential. Accurately describing the dynamic distribution, occurrence, and water-coning process of residual oil after bottom-water flooding is crucial for the development of bottom-water reservoirs. Therefore, conducting microscopic flooding experiments under reservoir conditions is crucial to provide important theoretical support for enhancing oil recovery in bottom-water reservoirs.

[0003] Methods for studying microscopic residual oil include core analysis and microsimulation. Core analysis analyzes oil-bearing thin sections of core rock to determine the distribution of residual oil within the reservoir pores and the distribution of oil and water. This method provides two key insights into the formation and distribution of residual oil: first, it allows for the evaluation of waterlogging and residual oil saturation in the coring well area; second, it provides the necessary parameters for indirect prediction of microscopic residual oil saturation. Micro-simulation technology includes core simulation model displacement experiments and ideal simulation model displacement experiments. The core simulation model displacement experiment uses real formation cores as experimental research objects, establishes a water-displacement oil physical model, conducts displacement experiments, and uses thin-section technology to analyze the displacement cores to directly describe the formation and distribution of residual oil. This method is currently the most convenient and intuitive method for studying residual oil. Its advantage is that it uses actual cores as water-displacement oil physical models and can accurately simulate the pore characteristics of the reservoir. Its disadvantage is that it cannot observe the dynamic process of water-displacement oil in real time, but can only observe the results. The ideal simulation model displacement experiment is based on a full understanding of the microscopic pore characteristics of reservoir rocks. By establishing an ideal reservoir simulation model, the residual oil displacement mechanism and influencing factors are studied, the microscopic pore structure and wettability changes of reservoir rocks are simulated, and the influencing factors of oil displacement efficiency in the water-displacement process under various conditions are studied. Although the simulation model cannot completely simulate all the characteristics of the core, and there is still a certain gap between the simulated porous medium and the actual core, the simulated glass model still has two advantages: on the one hand, by utilizing its light transmittance, the dynamic microscopic interaction process between the formation fluids during the oil recovery process can be clearly observed through imaging methods, overcoming the disadvantage of not being able to observe the dynamic process in the core experiment; on the other hand, the model can be reused, and the same model can be used to carry out different experimental schemes to compare the oil recovery effects, thereby eliminating the influence of model factors on parallel experiments.

[0004] CN 203515528 U and CN 203499659 U respectively disclose a microscopic glass model for displacement experiments. The models are made of photoetched glass and include a bottom plate and a top plate. The top plate has a liquid injection port and the bottom plate has a groove etched by hydrofluoric acid. The latter is based on the former, but the groove is filled with natural core powder or quartz sand. Both models are simple to manufacture and low in cost, but both fail to take into account the characteristics of strong bottom water. They can only simulate the natural energy drive of bottom water reservoirs through water drive, and cannot reflect the reservoir conditions of strong bottom water.

[0005] Therefore, we look forward to developing a microscopic physical model, experimental device and method for simulating bottom water reservoirs, which can simulate the development process of strong bottom water reservoirs under high temperature and high pressure conditions, and clarify the mechanism of improving the recovery rate of bottom water reservoirs by gas drive, chemical drive, etc. Summary of the Invention

[0006] The purpose of the present invention is to provide a microscopic physical model, experimental device and method for simulating bottom water reservoirs, so as to simulate the development process of strong bottom water reservoirs under high temperature and high pressure conditions and clarify the mechanism of improving the recovery rate of bottom water reservoirs by gas drive, chemical drive, etc.

[0007] In order to achieve the above object, the present invention provides a microscopic physical model for simulating a bottom water reservoir, wherein the microscopic physical model is made of a transparent material;

[0008] The microscopic physical model includes an oil-bearing characteristic area and a bottom water characteristic area, wherein the oil-bearing characteristic area and the bottom water characteristic area are located in the same plane, are adjacent to each other, and are interconnected;

[0009] A first injection channel is provided at one end of the bottom water characteristic zone away from the oil-bearing characteristic zone, a production channel is provided at one end of the oil-bearing characteristic zone away from the bottom water characteristic zone, and a second injection channel and a third injection channel are provided on both sides of the oil-bearing characteristic zone respectively.

[0010] Optionally, the microscopic physical model includes a bottom plate and a top plate;

[0011] The oil-bearing characteristic area and the bottom water characteristic area are arranged on the top surface of the bottom plate and are interconnected through a plurality of micropores;

[0012] The first injection channel extends from the bottom water feature area to the top edge of the bottom plate;

[0013] The production channel, the second injection channel and the third injection channel respectively extend from the oil-bearing characteristic area to the top edge of the bottom plate;

[0014] The top plate covers the top surface of the bottom plate.

[0015] Optionally, the bottom plate is frosted glass, and the top plate is flat glass.

[0016] Optionally, the oil-bearing characteristic area includes a plurality of pores, and the bottom water characteristic area is a cavity.

[0017] Optionally, the pores in the oil-bearing characteristic area are arranged in a positive rhythm, an anti-rhythmic arrangement, or a homogeneous arrangement.

[0018] Optionally, a partition is provided in the oil-bearing characteristic area.

[0019] The present invention also provides a microscopic experimental device for simulating bottom water reservoirs, comprising:

[0020] A reactor, wherein a viewing window is provided on the top of the reactor;

[0021] The above-mentioned microphysical model simulating a bottom water reservoir is arranged in the reactor;

[0022] A vacuum pumping system, connected to the reactor and the microscopic physical model, for vacuuming the interiors of the reactor and the microscopic physical model;

[0023] a first injection system, the first injection system being connected to the first injection channel and the reactor, respectively, and capable of injecting water into the bottom water characteristic area and the reactor, respectively;

[0024] a second injection system, the second injection system being connected to the second injection channel and the third injection channel, respectively, for injecting a displacement medium into the oil-bearing characteristic area;

[0025] A production control system, connected to the production channel of the microphysical model, for simulating the flow rate and pressure of the production well;

[0026] An image acquisition system is used to acquire images of the microscopic physical model through the viewing window.

[0027] Optionally, the first injection system includes a first injection pump and a first intermediate container, the first injection pump is connected to the first intermediate container, the first intermediate container is connected to the reactor and the first injection channel respectively, and valves are provided between the first intermediate container and the reactor and between the first intermediate container and the first injection channel respectively;

[0028] The second injection system includes a second intermediate container, a third intermediate container, and a second injection pump. The second intermediate container is connected to the second injection channel, the third intermediate container is connected to the third injection channel, and the second intermediate container and the third intermediate container are both connected to the second injection pump.

[0029] Valves are respectively provided between the second intermediate container and the second injection channel, and between the third intermediate container and the third injection channel.

[0030] Optionally, the output control system includes a back-pressure valve and a third injection pump, and the output channel is connected to the third injection pump through the back-pressure valve.

[0031] The present invention also provides a microscopic displacement experimental method for simulating a bottom water reservoir, using the above-mentioned microscopic experimental device for simulating a bottom water reservoir, the method comprises the following steps:

[0032] 1) Using a vacuum system to evacuate the interior of the reactor and the microscopic physical model;

[0033] 2) using a first injection system to fill the microscopic physical model and the reactor cavity with water;

[0034] 3) heating and pressurizing the reactor until the temperature and pressure of the microscopic physical model and the interior of the reactor reach the temperature and pressure of the target oil reservoir;

[0035] 4) injecting formation crude oil into the oil-bearing characteristic area using a second injection system to displace water from the oil-bearing characteristic area until the distribution of the formation crude oil in the oil-bearing characteristic area no longer changes;

[0036] 5) using a first injection system to inject water into the bottom water characteristic area to simulate a strong bottom water depletion recovery process, while simultaneously using a production control system to simulate the recovery mode of an actual oil well until the distribution of crude oil in the model no longer changes, and using an image acquisition system to continuously capture the changes in the distribution and occurrence state of crude oil in the microscopic model to obtain the oil recovery efficiency of the depletion recovery;

[0037] 6) A second injection system is used to inject a displacement medium into the oil-bearing characteristic area. After simulating strong bottom water depletion production, a scheme of using the displacement medium to enhance oil recovery is adopted. An image acquisition system is used to continuously capture the changes in crude oil distribution and occurrence state in the microscopic indoor model to obtain the oil displacement efficiency of different body media.

[0038] The beneficial effects of the present invention are:

[0039] 1. The microphysical model of the simulated bottom water reservoir of the present invention can simulate the development process of a strong bottom water reservoir under high temperature and high pressure conditions, clarifying the mechanism of enhanced oil recovery such as gas flooding and chemical flooding in bottom water reservoirs; can clearly observe the dynamic microscopic interaction process between formation fluids during the oil flooding process through imaging methods; and can be reused. The same model can be used to carry out experimental schemes with different displacement media to compare oil flooding effects, thereby eliminating the influence of model factors on parallel experiments.

[0040] 2. The experimental device of the present invention can be used to saturate the microscopic physical model with formation crude oil or bottom water under high temperature and high pressure conditions by changing the injection-production relationship of different channels; by controlling the injection pressure of the first injection system, the bottom water energy of different intensities can be simulated; by controlling the pressure or flow at the output end through the output control system, the working system of the production well can be simulated; by adjusting the injection pressure or flow of the second injection system, development plans and measures such as water injection, gas injection, and chemical injection can be simulated; by using the image acquisition system, the distribution pattern and occurrence state of the fluid (oil is brown, water is blue, and gas is colorless) in the microscopic physical model can be observed, the microscopic remaining oil distribution pattern of the bottom water reservoir under different conditions can be determined, and the recovery enhancement mechanism of the bottom water reservoir such as gas drive and chemical drive can be clarified. This device can highly simulate the temperature, pressure, geology, reservoir and bottom water environment of the oil reservoir, making the experimental results closer to the actual situation.

[0041] 3. By conducting microscopic displacement experiments on bottom water reservoirs using the method of the present invention, the oil displacement efficiency of depletion recovery can be obtained, and the oil displacement efficiency of different displacement media can be obtained for horizontal comparison to obtain the optimal solution for improving the recovery rate.

[0042] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0044] Figure 1 A schematic diagram of a microscopic experimental device for simulating a bottom water reservoir according to an embodiment of the present invention is shown.

[0045] Figure 2 A schematic diagram of a microscopic physical model in a reactor according to an embodiment of the present invention is shown.

[0046] Figure 3 A schematic diagram of a homogeneous microscopic physical model with partitions according to an embodiment of the present invention is shown.

[0047] Figure 4 A schematic diagram of a homogeneous microscopic physical model without partitions according to an embodiment of the present invention is shown.

[0048] Figure 5 A schematic diagram of an anti-rhythmic microscopic physical model according to an embodiment of the present invention is shown.

[0049] Figure 6 A schematic diagram of a positive rhythmic microscopic physical model according to an embodiment of the present invention is shown.

[0050] Description of Reference Numerals

[0051] 1. Microscopic physical model; 2. Reactor; 3. Window; 4. First injection pump; 5. First intermediate container; 6. Second intermediate container; 7. Third intermediate container; 8. Second injection pump; 9. Valve; 10. Back-pressure valve; 11. Third injection pump; 12. Vacuum system; 13. High-speed camera; 14. Image acquisition system; 15. Bottom light; 16. Collection device; 17. Metering device; 18. Oil-bearing characteristic area; 19. Bottom water characteristic area; 20. First injection channel; 21. Second injection channel; 22. Third injection channel; 23. Output channel; 24. Partition. DETAILED DESCRIPTION

[0052] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Instead, these embodiments are provided to make the present invention more thorough and complete and to fully convey the scope of the present invention to those skilled in the art.

[0053] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0054] The present invention discloses a microscopic physical model for simulating a bottom water reservoir, wherein the microscopic physical model is made of a transparent material;

[0055] The microscopic physical model includes an oil-bearing characteristic area and a bottom water characteristic area. The oil-bearing characteristic area and the bottom water characteristic area are located in the same plane, are adjacent to each other, and are interconnected.

[0056] A first injection channel is provided at one end of the bottom water characteristic zone away from the oil characteristic zone, an output channel is provided at one end of the oil characteristic zone away from the bottom water characteristic zone, and a second injection channel and a third injection channel are provided on both sides of the oil characteristic zone.

[0057] Specifically, the microphysical model of the simulated bottom water reservoir of the present invention can simulate the development process of a strong bottom water reservoir under high temperature and high pressure conditions, and clarify the mechanism of improving the recovery rate of bottom water reservoirs such as gas drive and chemical drive; it can clearly observe the dynamic microscopic interaction process between formation fluids during the oil displacement process through imaging methods; it can be reused, and the same model can be used to carry out experimental plans for different displacement media to compare the oil displacement effects, thereby eliminating the influence of model factors on parallel experiments.

[0058] As an option, the microphysical model includes a bottom plate and a top plate;

[0059] The oil-bearing characteristic area and the bottom water characteristic area are arranged on the top surface of the bottom plate and are interconnected through a plurality of micropores;

[0060] The first injection channel extends from the bottom water characteristic area to the top edge of the bottom plate;

[0061] The production channel, the second injection channel and the third injection channel extend from the oil-bearing characteristic area to the top edge of the bottom plate respectively;

[0062] The top plate covers the top surface of the bottom plate.

[0063] Specifically, the first injection channel is used to inject bottom water or provide power for simulating a strong bottom water depletion production process; the output channel is used to discharge formation crude oil or displaced medium; the second injection channel and the third injection channel are used to inject displacing medium.

[0064] As an option, the bottom panel is frosted glass and the top panel is flat glass.

[0065] Specifically, glass has heat resistance and strength that can meet experimental requirements, is easily available, is low-cost, and has good light transmittance. However, other transparent materials can also be used for the top and bottom plates, not limited to glass.

[0066] As an optional solution, the oil-bearing characteristic area includes multiple pores, and the bottom water characteristic area is a cavity.

[0067] Specifically, the distribution pattern and size of the pores are set according to the pore throat distribution and size of the target oil reservoir.

[0068] As an option, the pores in the oil-bearing characteristic zone are arranged in a positive rhythm, an anti-rhythmic arrangement, or a homogeneous arrangement.

[0069] As an option, baffles are provided in the oil-bearing characteristic area.

[0070] Specifically, some reservoirs may develop interlayers of different sizes, so setting up baffles can simulate strong bottom water reservoirs containing interlayers. The position and length of the baffles are set according to the distribution pattern of the interlayers in the target reservoir.

[0071] The present invention also discloses a microscopic experimental device for simulating bottom water reservoirs, comprising:

[0072] A reactor with a viewing window on the top;

[0073] The microscopic physical model for simulating a bottom water reservoir is set in a reactor;

[0074] A vacuum pumping system is connected to the reactor and the microscopic physical model, and is used to vacuum the interior of the reactor and the microscopic physical model;

[0075] a first injection system, the first injection system being connected to the first injection channel and the reactor, respectively, and capable of injecting water into the bottom water characteristic area and the reactor, respectively;

[0076] a second injection system, the second injection system being connected to the second injection channel and the third injection channel respectively, for injecting a displacement medium into the oil-bearing characteristic area;

[0077] The production control system is connected to the production channel of the micro-physical model and is used to simulate the flow rate and pressure of the production well;

[0078] Image acquisition system,The image acquisition system acquires images of the microscopic physical model through a window.

[0079] Specifically, the experimental device of the present invention can saturate the microscopic physical model with formation crude oil or bottom water under high temperature and high pressure conditions by changing the injection-production relationship of different channels; simulate bottom water energy of different intensities by controlling the injection pressure of the first injection system; simulate the working system of the production well by controlling the pressure or flow at the output end through the output control system; simulate development plans and measures such as water injection, gas injection, and chemical injection by adjusting the injection pressure or flow of the second injection system; use the image acquisition system to observe the distribution pattern and occurrence state of the fluid (oil is brown, water is blue, and gas is colorless) in the microscopic physical model, determine the microscopic remaining oil distribution pattern of the bottom water reservoir under different conditions, and clarify the recovery enhancement mechanism of the bottom water reservoir such as gas drive and chemical drive. This device can highly simulate the temperature, pressure, geology, reservoir and bottom water environment of the oil reservoir, making the experimental results closer to the actual situation.

[0080] As an optional solution, the first injection system includes a first injection pump and a first intermediate container, the first injection pump is connected to the first intermediate container, the first intermediate container is respectively connected to the reactor and the first injection channel, and valves are respectively provided between the first intermediate container and the reactor and between the first intermediate container and the first injection channel;

[0081] The second injection system includes a second intermediate container, a third intermediate container and a second injection pump, the second intermediate container is connected to the second injection channel, the third intermediate container is connected to the third injection channel, and the second intermediate container and the third intermediate container are both connected to the second injection pump;

[0082] Valves are respectively provided between the second intermediate container and the second injection channel, and between the third intermediate container and the third injection channel.

[0083] As an optional solution, the production control system includes a back pressure valve and a third injection pump, and the production channel is connected to the third injection pump through the back pressure valve.

[0084] Specifically, the output control system also includes a pressure measuring device, which uses the third injection pump to control the pressure or flow of the back pressure valve at the output end, can simulate the working system of the production well, and can intuitively obtain real-time pressure changes through the pressure measuring device.

[0085] The present invention also discloses a microscopic displacement experimental method for simulating a bottom water reservoir, using the above-mentioned microscopic experimental device for simulating a bottom water reservoir, the method comprises the following steps:

[0086] 1) Using a vacuum system to evacuate the interior of the reactor and the microscopic physical model;

[0087] 2) Filling the microscopic physical model and the reactor cavity with water using the first injection system;

[0088] 3) Heating and pressurizing the reactor until the temperature and pressure inside the microscopic physical model and the reactor reach the temperature and pressure of the target oil reservoir;

[0089] 4) injecting formation crude oil into the oil-bearing characteristic area using the second injection system to displace water from the oil-bearing characteristic area until the distribution of the formation crude oil in the oil-bearing characteristic area no longer changes;

[0090] 5) Using the first injection system to inject water into the bottom water characteristic area to simulate the strong bottom water depletion recovery process, while using the output control system to simulate the actual oil well production mode until the distribution of crude oil in the model no longer changes. The image acquisition system is used to continuously capture the changes in the distribution and occurrence state of crude oil in the microscopic indoor model to obtain the oil recovery efficiency of the depletion recovery;

[0091] 6) A second injection system is used to inject a displacement medium into the oil-bearing characteristic area. After simulating strong bottom water depletion production, a scheme of using the displacement medium to enhance oil recovery is adopted. An image acquisition system is used to continuously capture the changes in crude oil distribution and occurrence state in the microscopic indoor model to obtain the oil displacement efficiency of different body media.

[0092] Specifically, by conducting microscopic displacement experiments on bottom water reservoirs using the method of the present invention, the oil displacement efficiency of depletion recovery can be obtained, and the oil displacement efficiency of different displacement media can be obtained for horizontal comparison to obtain an optimal solution for improving recovery.

[0093] Example 1

[0094] Figure 1 A schematic diagram of a microscopic experimental device for simulating a bottom water reservoir in accordance with the present embodiment is shown; Figure 2 A schematic diagram of the microscopic physical model in the reactor of this embodiment is shown.

[0095] like Figure 1 As shown, the microscopic experimental device for simulating bottom water reservoirs includes a reactor 2, and a sapphire window 3 is provided on the top of the reactor 2;

[0096] The microscopic physical model 1 is set in the reactor 2, as shown in FIG. Figure 2 As shown, the microscopic physical model 1 includes a bottom plate and a top plate, the bottom plate is frosted glass, and the top plate is flat glass. The oil-bearing characteristic area 18 and the bottom water characteristic area 19 are adjacently arranged on the top surface of the bottom plate and interconnected through micropores to form a rectangular characteristic area, and the bottom water characteristic area 19 occupies a corner of the rectangular area; the right-angle end of the bottom water characteristic area 19 is connected to the first injection channel 20; the right-angle end of the oil-bearing characteristic area 18 opposite to the bottom water characteristic area 19 is connected to the production channel 23, and the other two right-angle ends are respectively connected to the second injection channel 21 and the third injection channel 22; the oil-bearing characteristic area 18 includes a plurality of pores and is uniformly arranged; the bottom water characteristic area 19 is a cavity, and a partition 24 is provided in the oil-bearing characteristic area 18; the top plate covers the top surface of the bottom plate.

[0097] The vacuum system 12 is connected to the reactor 2 and the microscopic physical model 1, and is used to vacuum the interior of the reactor 2 and the microscopic physical model 1;

[0098] The first injection pump 4 is connected to the first intermediate container 5, which is respectively connected to the reactor 2 and the first injection channel 20. Valves 9 are respectively provided between the first intermediate container 5 and the reactor 2 and between the first intermediate container 5 and the first injection channel 20, so as to be able to inject water into the bottom water characteristic area 19 and the reactor 2 respectively.

[0099] The second intermediate container 6 is connected to the second injection channel 21, and the third intermediate container 7 is connected to the third injection channel 22. The second intermediate container 6 and the third intermediate container 7 are both connected to the second injection pump 8. Valves are provided between the second intermediate container 6 and the second injection channel 21, and between the third intermediate container 7 and the third injection channel 22, respectively, for injecting displacement medium into the oil-bearing characteristic area 18.

[0100] The output channel 23 is connected to the third injection pump 11 through the back pressure valve 10 to simulate the flow rate and pressure of the production well. The output channel 23 is connected to the collection device 16 and the metering device 17 in sequence.

[0101] A high-speed camera 13 is aimed at the window 3 of the reactor 2 and is connected to an image acquisition system 14 to continuously capture the changes in the distribution and occurrence state of crude oil in the microscopic physical model 1, and cooperates with image processing software (including image recording software and pixel recognition and analysis software) to obtain the oil recovery efficiency of depletion mining or different enhanced oil recovery schemes. In order to facilitate image acquisition, a bottom light 15 is also set at the bottom of the reactor 2.

[0102] Using this experimental device, under high temperature and high pressure conditions, by changing the injection-production relationship of different injection channels, the microscopic physical model is saturated with formation crude oil and bottom water; the pressure of the injection pump connected to the bottom water characteristic area is controlled to simulate bottom water energy of different intensities; the pressure or flow of the back pressure valve at the output end is controlled to simulate the working system of the production well; the pressure or flow of the injection pump connected to any of the other two connecting ports is controlled to simulate development plans and measures such as water injection and gas injection; the distribution pattern and occurrence state of fluids (oil is brown, water is blue, and gas is colorless) in porous media are observed using high-speed cameras and image capture systems, the microscopic remaining oil distribution pattern of bottom water reservoirs under different conditions is determined, and the recovery enhancement mechanism of bottom water reservoirs such as water drive, gas drive, and chemical drive is clarified.

[0103] Example 2

[0104] Figure 3 A schematic diagram of a homogeneous microscopic physical model with a partition according to this embodiment is shown; Figure 4 A schematic diagram of a homogeneous microscopic physical model without a partition in this embodiment is shown; Figure 5 A schematic diagram of the anti-rhythmic microscopic physical model of this embodiment is shown; Figure 6 A schematic diagram of the positive rhythmic microscopic physical model of this embodiment is shown.

[0105] This embodiment discloses a microscopic displacement experimental method for simulating a bottom water reservoir, comprising the following steps:

[0106] Step 1: Create a bottom water reservoir microphysical model based on the main reservoir parameters such as actual reservoir physical properties, oil layer and water layer thickness ratio, bottom water strength, and interlayer water avoidance height.

[0107] According to the actual geological characteristics, a homogeneous microscopic physical model with partitions can be designed ( Figure 3 ), homogeneous microscopic physical model without partition ( Figure 4 ), anti-rhythmic microscopic physical model ( Figure 5 ), positive rhythmic microscopic physical model ( Figure 6) to meet the needs of experimental research. According to the distribution characteristics of reservoir interlayers, homogeneous microscopic physical models with and without partitions are designed and produced to study the influence of interlayers on the microscopic residual oil distribution in bottom water reservoirs, such as Figure 3 and Figure 4 The top of the bottom water characteristic area is 6 mm away from the first injection channel connected to the bottom water characteristic area, the partition is 4 mm above the top of the bottom water area, and the average permeability of the oil-bearing area is 760 md; According to the heterogeneity characteristics of the reservoir, the positive rhythm and reverse rhythm micro-physical models are designed and produced to study the microscopic residual oil distribution law of bottom water reservoirs with different rhythms, such as Figure 5 and Figure 6 The top of the bottom water feature area is 6 mm away from the first injection channel connected to the bottom water feature area. The positive rhythm high permeability layer is located 4 mm above the top of the bottom water feature area, with an average permeability of 1000 md. The rest of the area is a low permeability area with an average permeability of 300 md.

[0108] Step 2: Place the microscopic physical model in the reactor, press and seal the four functional connecting ports to the injection and output pipelines with sealing rings and bolts, and then seal the reactor with a sealing cover with a sapphire window.

[0109] Step 3: Use the vacuum system to vacuum the reactor and the model simultaneously until the pressure reaches -0.1 MPa.

[0110] Step 4: Inject water into the microscopic physical model and the reactor cavity. After the model and reactor are filled with water, heat and pressurize them until they reach the reservoir temperature and pressure.

[0111] Step 5: Inject formation crude oil into the microphysical model, use the back pressure valve and the third injection pump to control the output pressure, and discharge the water displaced by the crude oil in the model until the crude oil distribution in the model no longer changes.

[0112] Step 6: Inject water into the microphysical model to simulate the strong bottom water depletion production process. Use the back pressure valve and the third injection pump to simulate the working system of the actual oil well in a constant pressure or constant flow mode until the distribution of crude oil in the model no longer changes. Use a high-speed camera and image acquisition system to continuously capture the changes in the distribution and occurrence state of crude oil in the model, and use image processing software to obtain the oil recovery efficiency of depletion production.

[0113] Step 7: Inject water or gas (CO2, natural gas or nitrogen) or chemical solution into the microphysical model at a constant pressure or constant rate to simulate strong bottom water depletion production and other enhanced oil recovery schemes such as water drive, gas drive, and chemical drive. Use a high-speed camera and image acquisition system to continuously capture the changes in crude oil distribution and occurrence state in the model. Use image processing software to obtain the oil recovery efficiency of different enhanced oil recovery schemes.

[0114] While various embodiments of the present invention have been described above, the above description is intended to be illustrative, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A microphysical model for simulating bottom water reservoirs, characterized in that: The microscopic physical model is made of transparent material; The microscopic physical model includes an oil-bearing characteristic area and a bottom water characteristic area, wherein the oil-bearing characteristic area and the bottom water characteristic area are located in the same plane, are adjacent to each other, and are interconnected; A first injection channel is provided at a right-angle end of the bottom water characteristic area away from the oil-bearing characteristic area, a production channel is provided at a right-angle end of the oil-bearing characteristic area away from the bottom water characteristic area, and a second injection channel and a third injection channel are provided at right-angle ends on both sides of the oil-bearing characteristic area respectively; the first injection channel, the production channel, the second injection channel and the third injection channel are respectively arranged at the top edge of the bottom plate to form a symmetrical layout; The first injection channel is used to inject bottom water or provide power for simulating a strong bottom water depletion production process; the output channel is used to discharge formation crude oil or displaced medium; the second injection channel and the third injection channel are used to inject displacing medium; The oil-bearing characteristic area includes a plurality of pores, and the bottom water characteristic area is a cavity; The pores in the oil-bearing characteristic area are arranged in a positive rhythm, an anti-rhythmic arrangement, or a homogeneous arrangement; The microscopic physical model includes a bottom plate and a top plate; The oil-bearing characteristic area and the bottom water characteristic area are arranged on the top surface of the bottom plate and are interconnected through a plurality of micropores; The first injection channel extends from the bottom water feature area to the top edge of the bottom plate; The production channel, the second injection channel and the third injection channel respectively extend from the oil-bearing characteristic area to the top edge of the bottom plate; The top plate covers the top surface of the bottom plate.

2. The microphysical model for simulating bottom water reservoirs according to claim 1, characterized in that: The bottom plate is frosted glass, and the top plate is flat glass.

3. The microscopic physical model for simulating bottom water reservoir according to claim 1, characterized in that: A partition is provided in the oil-bearing characteristic area.

4. A microscopic experimental device for simulating bottom water reservoirs, characterized in that: include: A reactor, wherein a viewing window is provided on the top of the reactor; The microphysical model for simulating a bottom water reservoir according to any one of claims 1 to 3, wherein the microphysical model is arranged in the reactor; A vacuum pumping system, connected to the reactor and the microscopic physical model, for vacuuming the interiors of the reactor and the microscopic physical model; a first injection system, the first injection system being connected to the first injection channel and the reactor, respectively, and capable of injecting water into the bottom water characteristic area and the reactor, respectively; a second injection system, the second injection system being connected to the second injection channel and the third injection channel, respectively, for injecting a displacement medium into the oil-bearing characteristic area; A production control system, connected to the production channel of the microphysical model, for simulating the flow rate and pressure of the production well; An image acquisition system is used to acquire images of the microscopic physical model through the viewing window.

5. The microscopic experimental device for simulating bottom water reservoir according to claim 4, characterized in that: The first injection system includes a first injection pump and a first intermediate container. The first injection pump is connected to the first intermediate container. The first intermediate container is connected to the reactor and the first injection channel respectively. Valves are respectively provided between the first intermediate container and the reactor and between the first intermediate container and the first injection channel. The second injection system includes a second intermediate container, a third intermediate container, and a second injection pump. The second intermediate container is connected to the second injection channel, the third intermediate container is connected to the third injection channel, and the second intermediate container and the third intermediate container are both connected to the second injection pump. Valves are respectively provided between the second intermediate container and the second injection channel, and between the third intermediate container and the third injection channel.

6. The microscopic experimental device for simulating bottom water reservoir according to claim 4, characterized in that: The output control system includes a back pressure valve and a third injection pump, and the output channel is connected to the third injection pump through the back pressure valve.

7. A microscopic displacement experimental method for simulating bottom water reservoirs, using the microscopic experimental device for simulating bottom water reservoirs according to any one of claims 4 to 6, characterized in that: The method comprises the following steps: 1) Use the vacuum system to evacuate the interior of the reactor and the microscopic physical model; 2) using a first injection system to fill the microscopic physical model and the reactor cavity with water; 3) heating and pressurizing the reactor until the temperature and pressure of the microscopic physical model and the interior of the reactor reach the temperature and pressure of the target oil reservoir; 4) injecting formation crude oil into the oil-bearing characteristic area using a second injection system to displace water from the oil-bearing characteristic area until the distribution of the formation crude oil in the oil-bearing characteristic area no longer changes; 5) using a first injection system to inject water into the bottom water characteristic area to simulate a strong bottom water depletion recovery process, while simultaneously using a production control system to simulate the production mode of an actual oil well until the distribution of crude oil in the model no longer changes, and using an image acquisition system to continuously capture changes in the distribution and occurrence state of crude oil in the microscopic model to obtain the oil recovery efficiency of the depletion recovery; 6) A second injection system is used to inject a displacement medium into the oil-bearing characteristic area. After simulating strong bottom water depletion production, the displacement medium is used to enhance the oil recovery factor. An image acquisition system is used to continuously capture the changes in crude oil distribution and occurrence state in the microscopic indoor model to obtain the oil displacement efficiency of different body media.

Images