An experimental system and method for visualizing composite thermal flow in thermal recovery of heavy oil

Abstract

The application discloses a kind of thick oil thermal recovery composite drive heat flow visualization experimental system, including steam cooling collection system, steam cooling collection system side is sequentially provided with microfluidic model from top to bottom, array type thermocouple temperature measurement system and light source object table, microfluidic model is connected with waste liquid collection system, the pipeline connection port of steam cooling collection system is connected with steam generator and microsyringe, microfluidic model top is equipped with microscope, the experimental method of application this system is also disclosed the application is applicable to oil and gas exploitation experimental technical field, high-temperature steam, microfluidic technology, temperature measurement technology are applied in thick oil thermal recovery different viscosity reducer system drive oil effect and recovery ratio research, can greatly reduce time, manpower and material resources input, different viscosity reducer system can be compared to the viscosity reduction effect of multiphase fluid on thick oil, real-time observation and record microcosmic flow field, temperature field distribution in experiment can also be monitored, consider the influence of temperature on recovery ratio in thermal recovery process.

Description

Technical Field

[0001] This invention belongs to the field of experimental technology for oil and gas extraction, specifically an experimental system and method for visualizing the combined thermal flow of heavy oil thermal recovery. Background Technology

[0002] With the dwindling availability of conventional oil and current natural gas production still unable to meet demand, heavy oil is emerging as a crucial energy source to fill the energy gap in the next century. Heavy oil, also known as heavy crude oil, is characterized by low levels of light components, high levels of asphaltenes and gums, and low levels of straight-chain hydrocarbons, resulting in high viscosity and density, making extraction and transportation extremely difficult. Currently, a development method combining horizontal wells, viscosity reducers, nitrogen, and steam flooding has been proposed and is being applied on a large scale in oil fields. The mixture of viscosity reducers, steam, and nitrogen to form a high-temperature multiphase thermal fluid can significantly reduce the viscosity of heavy oil and substantially improve recovery rates; its viscosity-reducing effect on heavy oil has become a key focus in oil and gas extraction experiments.

[0003] Previous studies on viscosity reduction and oil recovery effects in heavy oil thermal recovery have included several Chinese patents. One, CN111197474A, proposed an experimental system to simulate changes in the thermal recovery flow field, capable of collecting and processing various parameters within a model container. Another, CN105952438A, proposed a visual two-dimensional simulation experimental device for heavy oil thermal recovery, capable of collecting and processing data from within the device and produced fluids. A third, CN106290786A, designed a core displacement device for heavy oil thermal recovery to calculate oil production. However, these experimental devices are limited by their design and can only perform macroscopic analyses, unable to simulate the microscopic oil displacement mechanism under the steam environment of heavy oil thermal recovery, or analyze the impact of temperature distribution during thermal recovery. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an experimental system and method for visualizing the thermal flow of heavy oil thermal recovery composite drive.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, an experimental system for visualizing the combined thermal flow of heavy oil thermal recovery includes a steam cooling and collection system. The steam cooling and collection system has a microfluidic model, an array of thermocouple temperature measurement systems, and a light source stage arranged sequentially from top to bottom on its side. The microfluidic model is connected to a waste liquid collection system. The pipeline connection port of the steam cooling and collection system is connected to a steam generator and a micro-sampler. A microscope is provided above the microfluidic model.

[0007] Preferably, valves are provided at the outlets of both the steam generator and the micro-sampler.

[0008] Preferably, the microsyringe is equipped with a constant pressure pump.

[0009] Preferably, the microscope is connected to a camera system, and the camera system is connected to a computer.

[0010] Preferably, the microfluidic model includes a pore network region, with one diagonal end of the pore network region serving as an injection end and the other diagonal end serving as an output end.

[0011] Preferably, the steam cooling and collection system is equipped with a microfluidic model holder, and the steam cooling and collection system has a model holding outlet on its side. The microfluidic model passes through the model holding outlet and is connected to the microfluidic model holder. The top of the steam cooling and collection system is equipped with a pipe connection port, and the bottom of the steam cooling and collection system is equipped with a drain outlet.

[0012] Preferably, the array thermocouple temperature measurement system includes a plurality of array thermocouple sensors, and all of the array thermocouple sensors are connected to a temperature display.

[0013] Preferably, the steam generator is connected to the steam cooling and collection system via a high-temperature resistant pipeline; the micro-syringe is connected to the steam cooling and collection system via a Teflon tube.

[0014] Preferably, the array-type thermocouple temperature measurement system is bonded to the microfluidic model with silicone oil.

[0015] Secondly, an experimental method for visualizing the heat flow of heavy oil thermal recovery composite drive includes the following steps:

[0016] S1 fabricated a microfluidic model, a vapor cooling and collection system, and an array thermocouple temperature measurement system, and assembled the experimental setup.

[0017] S2 takes a certain amount of heavy oil, viscosity reducer and nitrogen gas and draws them into the microsyringe respectively, and injects the heavy oil into the microfluidic model to saturate it;

[0018] S3: Adjust the parameters of the steam generator for injecting steam, open the line valve, start the steam generator, and maintain the steam injection state; adjust the array thermocouple temperature measurement system to start recording the temperature distribution changes of the microfluidic model; close the steam line, adjust the panel parameters of the constant pressure pump for injecting viscosity reducer, start the constant pressure pump, inject the viscosity reducer into the microfluidic model, and maintain the injection state; close the viscosity reducer line, adjust the panel parameters of the constant pressure pump for injecting nitrogen, start the constant pressure pump, inject nitrogen into the microfluidic model, and maintain the injection state; repeat the above steps multiple times.

[0019] S4 uses a camera system to display images on a computer screen, observes the oil displacement mechanism of viscosity reducers, records temperature field changes, takes overall photos of the microscopic model at different time points, obtains the distribution characteristics of heavy oil in the pore network, and calculates the changes in recovery rate to judge and compare the oil displacement effect of different viscosity reducer systems on heavy oil under steam assistance.

[0020] Preferably, in step S1, the microfluidic model body layer includes a channel configuration, which is a simulated formation pore network channel. The front end of the microfluidic model is an injection end, and the end is a waste liquid output end. The array thermocouple temperature measurement system is designed as multiple thermocouple temperature sensors arranged in a matrix and connected to a temperature display to monitor temperature changes.

[0021] Preferably, step S2 specifically includes:

[0022] S21 Prepare the heavy oil sample for the experiment and prepare the viscosity reducer solution;

[0023] S22 connects the experimental setup, saturates the heavy oil sample into the microfluidic model, and draws the viscosity reducer and nitrogen into their respective micro-injectors.

[0024] S23 Adjust the microscope and camera system to prepare for recording.

[0025] Preferably, step S3 specifically includes:

[0026] S31 draws heavy oil into a microsyringe and injects it into a saturated microfluidic model;

[0027] S32 sets multiple thermocouple sensors at the main channel, transition zone and boundary zone positions on the lower surface of the microfluidic model to connect and clamp the microfluidic model stably in the vapor cooling and collection system.

[0028] S33 connected the pipes properly and turned on the array thermocouple temperature measurement system to start monitoring the temperature distribution of the microfluidic model;

[0029] S34 adjusts the parameters of the steam generator for injecting steam, opens the valves of the steam generator and steam pipeline, injects the generated steam into the microfluidic model and maintains the injection state, and closes the valves and shuts down the steam generator after a period of time;

[0030] S35 adjusts the constant pressure pump panel parameters for injecting viscosity reducer, opens the viscosity reducer pipeline valve, injects the viscosity reducer into the microfluidic model and maintains the injection state, and closes the constant pressure pump and valve after a period of time;

[0031] S36 adjusts the constant pressure pump panel parameters for injecting nitrogen, opens the nitrogen pipeline valve, injects nitrogen into the microfluidic model and maintains the injection state, and closes the constant pressure pump and valve after a period of time;

[0032] Repeat the above three steps as needed to simulate multiple rounds of injection.

[0033] Preferably, step S4 specifically includes:

[0034] Adjust the microscope to select a suitable objective lens so that the eyepiece field of view is of the microfluidic model portion;

[0035] The system uses a camera to display images on a computer screen, taking pictures at different times, and then uses a computer to analyze the image results.

[0036] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0037] In this invention, high-temperature steam, microfluidics, and temperature measurement technologies are applied to the study of the oil displacement effect and recovery rate of different viscosity reducer systems in heavy oil thermal recovery. This can greatly reduce the input of time, manpower, and material resources. It can not only compare the viscosity reduction effect of multiphase fluids of different viscosity reducer systems on heavy oil, but also observe and record the micro-flow field in real time, and monitor the temperature field distribution in the experiment, taking into account the influence of temperature on the recovery rate during thermal recovery. Attached Figure Description

[0038] Figure 1 This is a diagram of the experimental system of the present invention;

[0039] Figure 2 This is a schematic diagram of the microfluidic model structure of the present invention;

[0040] Figure 3 This is a schematic diagram of the steam cooling and collection system of the present invention;

[0041] Figure 4 The present invention relates to an array-type thermocouple temperature measurement system;

[0042] Figure 5 This is a schematic diagram illustrating the combined oil displacement effect of different viscosity-reducing agent systems in Example 3 of the present invention;

[0043] Figure 6 This is a schematic diagram of the temperature recording points in Embodiment 4 of the present invention;

[0044] Figure 7 This is a schematic diagram illustrating the oil displacement effects of different methods in Embodiment 4 of the present invention;

[0045] Figure 8 This is a schematic diagram illustrating the changes in recovery rate in Embodiment 5 of the present invention;

[0046] Reference numerals: 1. Constant pressure pump; 2. Steam generator; 3. Steam cooling and collection system; 4. Microfluidic model; 5. Array thermocouple temperature measurement system; 6. Light source stage; 7. Waste liquid collection system; 8. Micro-injector; 9. Microscope; 10. Camera system; 11. Valve; 12. Pore network region; 13. Injection end; 14. Output end; 15. Pipe connection port; 16. Microfluidic model holder; 17. Model holder outlet; 18. Drain outlet; 19. Array thermocouple sensor; 20. Temperature display. Detailed Implementation

[0047] The specific embodiments of the present invention are described in detail below.

[0048] The "range" disclosed in this invention is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 10–50 is listed for a specific parameter, it is also expected that ranges of 10–40 and 20–50 are also included. Furthermore, if the minimum range values ​​are 1 and 2, and the maximum range values ​​are 3, 4, and 5, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0–5" means that all real numbers between "0–5" have been listed herein; "0–5" is merely a shortened representation of these numerical combinations.

[0049] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0050] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0051] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0052] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0053] Unless otherwise specified, the reaction will proceed under normal temperature and pressure conditions.

[0054] Unless otherwise specified, all parts or percentages are by weight or by weight percentage.

[0055] In this invention, all the substances used are known substances that can be purchased or synthesized by known methods.

[0056] In this invention, all the devices or equipment used are conventional devices or equipment known in the art and are readily available.

[0057] The following embodiments further illustrate the specific implementation of the experimental system and method for visualizing the combined thermal flow of heavy oil thermal recovery, according to the present invention. The experimental system and method for visualizing the combined thermal flow of heavy oil thermal recovery, according to the present invention, are not limited to the descriptions in the following embodiments.

[0058] Example 1:

[0059] An experimental system for visualizing the heat flow of heavy oil thermal recovery combined with flooding, such as... Figure 1 As shown, it includes a steam cooling and collection system 3. From top to bottom, the sides of the steam cooling and collection system 3 are provided with a microfluidic model 4, an array thermocouple temperature measurement system 5, and a light source stage 6. The microfluidic model 4 is connected to the waste liquid collection system 7. The pipeline connection port 15 of the steam cooling and collection system 3 is connected to the steam generator 2 and the micro-injector 8. A microscope 9 is provided above the microfluidic model 4.

[0060] Furthermore, valves 11 are provided at the outlets of both the steam generator 2 and the micro-sampler 8.

[0061] Furthermore, the micro-syringe 8 is equipped with a constant pressure pump 1.

[0062] Furthermore, the microscope 9 is connected to the camera system 10, and the camera system 10 is connected to the computer.

[0063] Furthermore, such as Figure 2 As shown, the microfluidic model 4 includes a pore network region 12, with one diagonal end of the pore network region 12 being the injection end 13 and the other diagonal end of the pore network region 12 being the output end 14. The main body layer and bottom carrier of the microfluidic model 4 are made of silica. The main body layer of the microfluidic model includes a channel configuration, which is a simulated formation pore network channel, with each channel having a height of 50 μm.

[0064] Furthermore, such as Figure 3 As shown, the steam cooling and collection system 3 is equipped with a microfluidic model holder 16. The steam cooling and collection system 3 has a model holding outlet 17 on its side. The microfluidic model 4 passes through the model holding outlet 17 and is connected to the microfluidic model holder 16. The top of the steam cooling and collection system 3 is equipped with a pipe connection port 15, and the bottom of the steam cooling and collection system 3 is equipped with a drain outlet 18. The steam cooling and collection system 3 is made of plexiglass and has inlets and outlets for connecting pipes and models.

[0065] Furthermore, such as Figure 4 As shown, the array thermocouple temperature measurement system 5 includes several array thermocouple sensors 19, all of which are connected to the temperature display 20. The array thermocouple temperature measurement system 5 is designed with multiple thermocouple temperature sensors arranged in a matrix and connected to the temperature display to monitor temperature changes.

[0066] Furthermore, the steam generator 2 is connected to the pipeline connection port 15 of the steam cooling and collection system 3 via a high-temperature resistant pipeline; the micro-injector 8 is connected to the pipeline connection port 15 of the steam cooling and collection system 3 via a Teflon tube.

[0067] Furthermore, the array-type thermocouple temperature measurement system 5 and the microfluidic model 4 are coated with silicone oil and bonded together.

[0068] Example 2:

[0069] An experimental method for visualizing the heat flow of heavy oil thermal recovery combined with flooding includes the following steps:

[0070] S1. Construct microfluidic model 4, vapor cooling and collection system 3, and array thermocouple temperature measurement system 5, and assemble experimental device;

[0071] S2 takes a certain amount of heavy oil, viscosity reducer and nitrogen gas and draws them into the micro-syringe 8 respectively, and injects the heavy oil into the microfluidic model 4 to saturate it;

[0072] S3 adjusts the parameters of the steam generator 2 for injecting steam, opens the line valve, turns on the steam generator 2, and maintains the steam injection state; adjusts the array thermocouple temperature measurement system 5 to start recording the temperature distribution changes of the microfluidic model 4; closes the steam line, adjusts the panel parameters of the constant pressure pump 1 for injecting viscosity reducer, turns on the constant pressure pump 1, injects the viscosity reducer into the microfluidic model 4, and maintains the injection state; closes the viscosity reducer line, adjusts the panel parameters of the constant pressure pump 1 for injecting nitrogen, turns on the constant pressure pump 1, injects nitrogen into the microfluidic model 4, and maintains the injection state; repeat the above steps multiple times;

[0073] S4 uses a camera system 10 to display images on a computer screen, observe the oil displacement mechanism of viscosity reducers, record temperature field changes, take overall photos of the microscopic model at different time points, obtain the distribution characteristics of heavy oil in the pore network, and calculate the changes in recovery rate to judge and compare the oil displacement effect of different viscosity reducer systems on heavy oil under steam assistance.

[0074] Furthermore, in step S1, the main body of the microfluidic model 4 includes a channel configuration, which is a simulated formation pore network channel. The front end of the microfluidic model 4 is an injection end 13, and the end is a waste liquid output end 14. The array thermocouple temperature measurement system 5 is designed as a matrix arrangement of multiple thermocouple temperature sensors connected to a temperature display to monitor temperature changes.

[0075] Furthermore, step S2 specifically includes:

[0076] S21 Prepare the heavy oil sample for the experiment and prepare the viscosity reducer solution;

[0077] S22 Connect the experimental setup, saturate the heavy oil sample into the microfluidic model 4, and draw the viscosity reducer and nitrogen into their respective micro-injectors 8;

[0078] S23 Adjust the microscope 9 and the camera system 10 to prepare for recording.

[0079] Furthermore, step S3 specifically includes:

[0080] S31 draws heavy oil into a microsyringe and injects it into a saturated microfluidic model;

[0081] S32 sets multiple thermocouple sensors at the main channel, transition zone and boundary zone positions on the lower surface of the microfluidic model to connect and clamp the microfluidic model stably in the vapor cooling and collection system.

[0082] S33 connected the pipes properly and turned on the array thermocouple temperature measurement system to start monitoring the temperature distribution of the microfluidic model;

[0083] S34 adjusts the parameters of the steam generator for injecting steam, opens the valves of the steam generator and steam pipeline, injects the generated steam into the microfluidic model and maintains the injection state, and closes the valves and shuts down the steam generator after a period of time;

[0084] S35 adjusts the constant pressure pump panel parameters for injecting viscosity reducer, opens the viscosity reducer pipeline valve, injects the viscosity reducer into the microfluidic model and maintains the injection state, and closes the constant pressure pump and valve after a period of time;

[0085] S36 adjusts the constant pressure pump panel parameters for injecting nitrogen, opens the nitrogen pipeline valve, injects nitrogen into the microfluidic model and maintains the injection state, and closes the constant pressure pump and valve after a period of time;

[0086] Repeat the above three steps as needed to simulate multiple rounds of injection.

[0087] Furthermore, step S4 specifically includes:

[0088] Adjust the microscope to select a suitable objective lens so that the eyepiece field of view is of the microfluidic model portion;

[0089] The system uses a camera to display images on a computer screen, taking pictures at different times, and then uses a computer to analyze the image results.

[0090] Example 3:

[0091] This study analyzes the oil displacement mechanism of a viscosity reducer system for heavy oil. The aim is to clarify the actual viscosity-reducing mechanism of this heavy oil thermal recovery viscosity reducer system and improve the actual recovery rate of heavy oil. The steps include:

[0092] Preparation phase:

[0093] Prepare the heavy oil sample for the experiment. Prepare viscosity reducer solution A;

[0094] Connect the experimental setup, saturate the microscopic model with the heavy oil sample, and draw the viscosity reducer and nitrogen gas into their respective microsyringes. Avoid drawing air into the microsyringes.

[0095] Adjust the microscope and camera system, and prepare for recording.

[0096] Adjust the steam generator parameters to set the steam temperature to 150℃ and 0.4MPa, open the line valve, start the steam generator, and maintain the steam injection state for 40 minutes; at the same time, adjust the temperature measurement system to start recording the temperature distribution changes of the model.

[0097] Turn off the steam line, adjust the constant pressure pump panel parameters for injecting viscosity reducer to an injection rate of 50 μL / min and an injection volume of 500 μL, turn on the constant pressure pump, open the line valve, inject the viscosity reducer into the microfluidic model and maintain the injection state;

[0098] Turn off the viscosity reducer circuit, adjust the constant pressure pump panel parameters for injecting nitrogen to an injection rate of 100 μL / min and an injection volume of 2000 μL, turn on the constant pressure pump, open the circuit valve, inject nitrogen into the microfluidic model and maintain the injection state.

[0099] During the injection process, the flow of heavy oil after viscosity reduction was observed. Continuous photographs were taken at different points, and the results are as follows: Figure 5 As shown, where Figure 5 (a) Image after steam drive Figure 5 (b) Image after viscosity reducer treatment Figure 5(c) is the image after nitrogen displacement.

[0100] Example 4:

[0101] To clarify the effect of nitrogen gas on the temperature field in a certain viscosity reducer system. The aim is to determine the effect of vapor drive on the temperature field after nitrogen injection. This includes the following steps:

[0102] Preparation phase:

[0103] Prepare the heavy oil sample for the experiment. Prepare viscosity reducer solution B.

[0104] Connect the experimental setup, saturate the microscopic model with the heavy oil sample, and draw the viscosity reducer and nitrogen gas into their respective microsyringes. Avoid drawing air into the microsyringes.

[0105] Adjust the microscope and camera system, and prepare for recording.

[0106] Adjust the steam generator parameters to set the steam temperature to 150℃ and 0.4MPa, open the line valve, start the steam generator, and maintain the steam injection state for 40 minutes; at the same time, adjust the temperature measurement system to start recording the temperature distribution changes of the model.

[0107] Turn off the steam line, adjust the constant pressure pump panel parameters for injecting viscosity reducer to an injection rate of 50 μL / min and an injection volume of 500 μL, turn on the constant pressure pump, open the line valve, inject the viscosity reducer into the microfluidic model and maintain the injection state;

[0108] Turn off the viscosity reducer circuit, adjust the constant pressure pump panel parameters for injecting nitrogen to an injection rate of 100 μL / min and an injection volume of 2000 μL, turn on the constant pressure pump, open the circuit valve, inject nitrogen into the microfluidic model and maintain the injection state.

[0109] Close the nitrogen line, open the steam line valve, start the steam generator, and maintain steam injection for 40 minutes.

[0110] Overall images were taken at different time points during the injection process, and temperature recording points were as follows: Figure 6 As shown, the temperature field changes at different points were recorded, and the results are as follows. Figure 7 As shown, where, Figure 7 (a) shows the nitrogen distribution after secondary steam drive. Figure 7 (b) Temperature distribution at different locations;

[0111] Table 1. Temperature field results of Example 4

[0112]

[0113] Example 5:

[0114] Determine the optimal blending ratio for multiple rounds of oil displacement using a specific compound viscosity reducer system. The aim is to guide the blending ratio of two heavy oil viscosity reducers to achieve the best viscosity-reducing effect. This includes the following steps:

[0115] 1. Preparation stage:

[0116] Prepare the heavy oil sample for the experiment. Mix the two viscosity reducers A and B in ratios of 1:1, 2:1 and 3:1 respectively to prepare three compound viscosity reducers a, b and c. Record the compounding ratio of the samples in detail.

[0117] (2) Connect the experimental setup, saturate the heavy oil sample into the micro-model, and draw the viscosity reducer and nitrogen into their respective micro-syringes. Avoid drawing air into the micro-syringes.

[0118] (3) Adjust the microscope and camera system and prepare for recording.

[0119] 2. Adjust the steam generator parameters to set the steam temperature to 150℃ and 0.4MPa, open the line valve, start the steam generator, and maintain the steam injection state for 40 minutes; at the same time, adjust the temperature measurement system to start recording the temperature distribution changes of the model.

[0120] 3. Close the steam line, adjust the constant pressure pump panel parameters for injecting viscosity reducer to 50 μL / min and 500 μL, turn on the constant pressure pump, open the line valve, inject the viscosity reducer into the microfluidic model and maintain the injection state;

[0121] 4. Turn off the viscosity reducer circuit, adjust the constant pressure pump panel parameters for injecting nitrogen to 100 μL / min and 2000 μL, turn on the constant pressure pump, open the circuit valve, inject nitrogen into the microfluidic model and maintain the injection state;

[0122] 5. Close the nitrogen line, open the steam line valve, start the steam generator, and maintain steam injection for 40 minutes;

[0123] 4. By performing the above steps on different proportions of viscosity reducers and comparing the changes in overall recovery rate, the optimal compound ratio of the two viscosity reducers can be determined. The results are as follows: Figure 8 As shown.

[0124] By adopting the above technical solution:

[0125] A microfluidic model simulating the formation pore network was constructed for oil displacement experiments. A steam generator produced high-temperature steam. A constant-pressure pump propelled a micro-sampler to inject heavy oil, viscosity reducers, and nitrogen. A steam cooling system was constructed to cool and collect overflow steam. An array of thermocouples was constructed to monitor temperature distribution changes in the microfluidic model. Microscopic images were displayed on a computer to record the oil displacement mechanism of the viscosity reducer and changes in oil recovery. This experimental system can compare the effects of different viscosity reducer systems on heavy oil, observe and record the microscopic flow field of multiphase thermal fluids in real time, and monitor the temperature field during the experiment, considering the impact of temperature on oil recovery during thermal recovery.

[0126] It has the following advantages:

[0127] It can simulate the composite oil displacement process of different viscosity reducer systems in heavy oil thermal recovery;

[0128] The mechanism of action of different viscosity reducer systems on heavy oil can be shown through the microscopic flow field of high-temperature multiphase fluid in a microfluidic model;

[0129] It can monitor the temperature distribution changes of the micro-flow field in a steam environment in real time at different points in the microfluidic model.

[0130] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. An experimental system for visualizing the combined heat flow of heavy oil thermal recovery, characterized in that: The system includes a steam cooling and collection system (3), on which a microfluidic model (4), an array thermocouple temperature measurement system (5), and a light source stage (6) are arranged sequentially from top to bottom on the side. The microfluidic model (4) is connected to a waste liquid collection system (7). The pipeline connection port (15) of the steam cooling and collection system (3) is connected to a steam generator (2) and a micro-sampler (8). A microscope (9) is provided above the microfluidic model (4).

2. The experimental system for visualizing the combined thermal flux of heavy oil thermal recovery as described in claim 1, characterized in that: Valves (11) are provided at the outlets of the steam generator (2) and the micro-sampler (8).

3. The experimental system for visualizing the combined thermal flux of heavy oil thermal recovery as described in claim 1, characterized in that: The micro-injector (8) is equipped with a constant pressure pump (1).

4. The experimental system for visualizing the combined thermal flux of heavy oil thermal recovery as described in claim 1, characterized in that: The microscope (9) is connected to the camera system (10), which is connected to a computer.

5. The experimental system for visualizing the combined thermal flux of heavy oil thermal recovery as described in claim 1, characterized in that: The microfluidic model (4) includes a pore network region (12), with one diagonal end of the pore network region (12) being the injection end (13) and the other diagonal end of the pore network region (12) being the output end (14).

6. The experimental system for visualizing the combined thermal flux of heavy oil thermal recovery as described in claim 1, characterized in that: The steam cooling collection system (3) is equipped with a microfluidic model holder (16). The steam cooling collection system (3) has a model holding outlet (17) on its side. The microfluidic model (4) passes through the model holding outlet (17) and is connected to the microfluidic model holder (16). The top of the steam cooling collection system (3) is equipped with a pipe connection port (15), and the bottom of the steam cooling collection system (3) is equipped with a drain outlet (18).

7. The experimental system for visualizing the combined thermal flow of heavy oil thermal recovery as described in claim 1, characterized in that: The array thermocouple temperature measurement system (5) includes several array thermocouple sensors (19), and all of the array thermocouple sensors (19) are connected to a temperature display (20).

8. The experimental system for visualizing the combined thermal flux of heavy oil thermal recovery as described in claim 1, characterized in that: The steam generator (2) is connected to the steam cooling and collection system (3) via a high-temperature resistant pipeline and a pipeline connection port (15); the micro-injector (8) is connected to the steam cooling and collection system (3) via a Teflon tube and a pipeline connection port (15).

9. The experimental system for visualizing the combined thermal flux of heavy oil thermal recovery as described in claim 1, characterized in that: The array thermocouple temperature measurement system (5) is coated with silicone oil and bonded to the microfluidic model (4).

10. An experimental method for visualizing the heat flow of heavy oil thermal recovery combined with flooding, characterized in that, Includes the following steps: S1. Fabricate a microfluidic model (4), a vapor cooling and collection system (3), and an array thermocouple temperature measurement system (5), and assemble the experimental setup. S2 takes a certain amount of heavy oil, viscosity reducer and nitrogen gas and draws them into the micro-syringe (8) respectively, and injects the heavy oil into the microfluidic model (4) to saturate it; S3 adjusts the parameters of the steam generator (2) for injecting steam, opens the line valve, turns on the steam generator (2), and maintains the steam injection state; adjusts the array thermocouple temperature measurement system (5) to start recording the temperature distribution changes of the microfluidic model (4); closes the steam line, adjusts the panel parameters of the constant pressure pump (1) for injecting viscosity reducer, turns on the constant pressure pump (1), injects the viscosity reducer into the microfluidic model (4), and maintains the injection state; closes the viscosity reducer line, adjusts the panel parameters of the constant pressure pump (1) for injecting nitrogen, turns on the constant pressure pump (1), injects nitrogen into the microfluidic model (4), and maintains the injection state; repeats the above steps multiple times; S4 uses a camera system (10) to display images on a computer screen, observe the oil displacement mechanism of viscosity reducers, record temperature field changes, take overall photos of the micro-model at different time points, obtain the distribution characteristics of heavy oil in the pore network, calculate the recovery rate change, and thus judge and compare the oil displacement effect of different viscosity reducer systems on heavy oil under steam assistance.

11. The experimental method for visualizing the combined thermal flux of heavy oil thermal recovery as described in claim 10, characterized in that, In step S1, the microfluidic model (4) includes a channel configuration in its main body layer. The channel configuration is a simulated formation pore network channel. The front end of the microfluidic model (4) is an injection end (13), and the end is a waste liquid output end (14). The array thermocouple temperature measurement system (5) is designed as a matrix arrangement of multiple thermocouple temperature sensors connected to a temperature display to monitor temperature changes.

12. The experimental method for visualizing the combined thermal flux of heavy oil thermal recovery as described in claim 10, characterized in that, Step S2 specifically includes: S21 Prepare the heavy oil sample for the experiment and prepare the viscosity reducer solution; S22 Connect the experimental setup, saturate the heavy oil sample into the microfluidic model (4), and draw the viscosity reducer and nitrogen into their respective micro-injectors (8); S23 Adjust the microscope (9) and the camera system (10) to prepare for recording.

13. The experimental method for visualizing the combined thermal flux of heavy oil thermal recovery as described in claim 10, characterized in that, Step S3 specifically includes: S31 draws heavy oil into a microsyringe and injects it into a saturated microfluidic model; S32 sets multiple thermocouple sensors at the main channel, transition zone and boundary zone positions on the lower surface of the microfluidic model to connect and clamp the microfluidic model stably in the vapor cooling and collection system. S33 connected the pipes properly and turned on the array thermocouple temperature measurement system to start monitoring the temperature distribution of the microfluidic model; S34 adjusts the parameters of the steam generator for injecting steam, opens the valves of the steam generator and steam pipeline, injects the generated steam into the microfluidic model and maintains the injection state, and closes the valves and shuts down the steam generator after a period of time; S35 adjusts the constant pressure pump panel parameters for injecting viscosity reducer, opens the viscosity reducer pipeline valve, injects the viscosity reducer into the microfluidic model and maintains the injection state, and closes the constant pressure pump and valve after a period of time; S36 adjusts the constant pressure pump panel parameters for injecting nitrogen, opens the nitrogen pipeline valve, injects nitrogen into the microfluidic model and maintains the injection state, and closes the constant pressure pump and valve after a period of time; Repeat the above three steps as needed to simulate multiple rounds of injection.

14. The experimental method for visualizing the combined thermal flux of heavy oil thermal recovery as described in claim 10, characterized in that, Step S4 specifically includes: Adjust the microscope to select a suitable objective lens so that the eyepiece field of view is of the microfluidic model portion; The system uses a camera to display images on a computer screen, taking pictures at different times, and then uses a computer to analyze the image results.

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