Device and experimental method for simulating influence of steam injection on physical properties of thickened oil

Abstract

The invention provides a device and an experimental method.The device comprises an injection system, a model system, a pressure control system, an output system and a data acquisition system.The injection system is connected to the model system and injects water or oil into the model system, the model system comprises a plurality of model pipes, and the model pipes are connected with the pressure control system; the pressure control system is connected to the model system and the data acquisition system, controls the pressure of the plurality of model pipes in the model system in a constant pressure mode to form different pressure gradients and transmits pressure information to the data acquisition system, and the output system is connected to the model system and outputs the pressure information to the data acquisition system. The products of the model system are subjected to gas-liquid separation and gas-liquid metering respectively. According to the device for simulating the influence of steam injection on the physical property of the thick oil and the experimental method, the change condition of the physical property of the crude oil after steam injection can be analyzed, and a powerful basis is provided for optimization of injection-production parameters of a steam injection production scheme.

Description

Technical Field

[0001] The present invention relates to the technical field of indoor experiments for oil extraction processes, and particularly to an apparatus and an experimental method for simulating the influence of steam injection on the physical properties of heavy oil. Background Art

[0002] Heavy oil has poor fluidity and high viscosity, and it is difficult to extract it using conventional oil and gas extraction methods. Currently, thermal recovery methods such as steam soaking and steam flooding are widely used in the development of heavy oil reservoirs, and the economic effects are very good. Steam soaking is the most widely used thermal oil recovery method, and the heavy oil production using steam soaking in China is close to 80%. The recovery rate of steam soaking is generally about 20%, and the recovery rate of steam flooding can generally reach more than 50%. Therefore, for a heavy oil reservoir, it is a common production method to first perform steam soaking for a certain period and then switch to steam flooding. Both steam soaking and steam flooding are steam injection development methods. High-temperature and high-pressure steam is injected into the reservoir to heat the underground heavy oil, reducing its viscosity and enhancing its fluidity, thereby improving the oil production efficiency. The steam distillation effect is one of the main production mechanisms of steam soaking and steam flooding. The steam distillation rate of crude oil mainly depends on the properties of the crude oil itself and has nothing to do with porous media, the original oil volume (oil saturation), and the steam injection rate, etc.; when the steam temperature is increased under saturated conditions, the steam distillation rate of crude oil slightly increases; while superheated steam can greatly increase the steam distillation rate of crude oil, especially for heavier crude oil, this phenomenon is more obvious. The steam distillation effect changes the physical properties of crude oil, and it is also found that the physical properties of crude oil change more significantly after the interaction between crude oil and superheated steam. Therefore, analyzing the influence of steam injection on the physical properties of heavy oil and providing reference experimental theoretical support for the steam injection development method of heavy oil reservoirs is also of great significance for the research on the optimization of process parameters. Such an indoor research process requires an apparatus and an experimental method for simulating the influence of steam injection on the physical properties of heavy oil.

[0003] Scholars have conducted a large number of indoor studies on steam soaking and steam flooding production methods. The article "Development and Application of an Indoor Simulation Experiment Apparatus for High-Pressure Soaking of Heavy Oil" involves an indoor simulation experiment apparatus for high-pressure soaking of heavy oil, which mainly includes three parts: an injection-production system, a sand-packed model simulating the formation, and a fluid temporary storage and energy storage system. It solves the problems of the "soaking" and "spitting" capabilities and heat retention of the sand-packed model in the heavy oil soaking simulation experiment. Using this apparatus, cold production, heating stimulation, and steam soaking experiments of heavy oil have been carried out. However, this technology cannot simulate the near-wellbore zone, the middle reservoir zone of the reservoir, and the far-wellbore zone of the reservoir, nor does it involve the relevant content and experimental method for analyzing the influence of steam injection on the physical properties of heavy oil.

[0004] Prior art 2: A steam stimulation visualization experiment device (authorization announcement number: CN 216043667U). This utility model experiment device is provided with an experimental passage and a measurement passage. A visualization filling model for simulating steam stimulation experiments is arranged on the experimental passage. A first electronic pressure gauge for measuring the pressure of the production well in the visualization filling model and a microscope for observing the heavy oil reservoir are arranged on the measurement passage. The seepage image of the heavy oil reservoir and the elastic energy data stored in the reservoir during the steam stimulation experiment can be observed and obtained. The acquisition of this data is of great significance for analyzing the effect of steam stimulation on the heavy oil reservoir from a microscopic perspective. However, it is impossible to carry out the analysis of the change in crude oil physical properties after steam injection.

[0005] Some scholars have also carried out research on the change law of reservoir physical properties during the steam injection development process of heavy oil reservoirs. For example, an experimental evaluation system for the influence of superheated steam on reservoirs (authorization announcement number: CN105041281B) consists of an injection system, a steam generation system, an oil reservoir model, and a production system. The injection system consists of a metering pump, its frequency regulator, pressure regulator, and flow regulator. The steam generation system consists of an electric heating furnace, its temperature control component, and steam pressure detection component. The oil reservoir model is a sand-filled closed three-dimensional structure, with the model being sealed and pressure-resistant, the outer surface being heat-insulated, 5 rows and 5 columns of thermocouples being installed inside, pressure measurement equipment and a temperature and pressure data acquisition system being installed on the side of the model. The production system includes the separation of the produced fluid, cooling and heat exchange, oil and water collection, and associated gas collection. This experimental system mainly conducts laboratory evaluations of the technical effects of superheated steam SAGD technology. This technology focuses on the physical property changes of reservoir rocks and does not involve the analysis of the influence of steam injection on the physical properties of crude oil.

[0006] The above prior arts are all quite different from the present invention and fail to solve the technical problems we want to solve. Therefore, we have invented a new device and experimental method for simulating the influence of steam injection on the physical properties of heavy oil. Summary of the Invention

[0007] The purpose of the present invention is to provide a device and experimental method for simulating the influence of steam injection on the physical properties of heavy oil, which can analyze the change in crude oil physical properties after steam injection and provide a strong basis for optimizing the injection and production parameters of the steam injection development plan.

[0008] The object of the present invention can be achieved by the following technical measures: a device for simulating the influence of steam injection on the physical properties of heavy oil. The device for simulating the influence of steam injection on the physical properties of heavy oil includes an injection system, a model system, a pressure control system, a production system, and a data acquisition system. The injection system is connected to the model system and injects water or saturated oil into the model system. The model system includes a plurality of model tubes. The pressure control system is connected to the model system and the data acquisition system, controls the pressure of the plurality of model tubes in the model system through a constant pressure mode, forms different pressure gradients, and transmits pressure information to the data acquisition system. The production system is connected to the model system, and performs gas-liquid separation and separate measurement of gas and liquid on the products of the model system.

[0009] The object of the present invention can also be achieved by the following technical measures:

[0010] The injection system includes a water source, a saturated oil device, and an injection pump. The water source is connected to the injection pump through a pipeline. The injection pump is connected to the model system through a pipeline and a valve. When the valve is opened, the injection pump injects water into the model system through the pipeline; when saturated with oil, the process is switched through the valve. The water source is connected to the injection pump through a pipeline. The injection pump is connected to the saturated oil device through a pipeline. The saturated device is connected to the model system through a pipeline. Water is injected into the bottom of the saturated device through the injection pump, and the oil in the saturated device is driven to be injected into the model through the pipeline.

[0011] The saturated oil device is an intermediate container, and is equipped with heat preservation, heating, and temperature control devices on the outer layer. The temperature of the saturated oil device is controlled by the temperature control device and can be set manually; the temperature acquisition information is transmitted to the data acquisition system and can also be controlled by a computer.

[0012] The model system includes a plurality of model tubes and a plurality of constant temperature boxes corresponding to each model tube. The plurality of model tubes are respectively placed into the corresponding constant temperature boxes. The plurality of model tubes are connected in the order from smallest to largest in diameter. Pressure monitoring points are respectively provided at the inlet end and the outlet end of each model tube. The temperature of the constant temperature box can be set respectively, and is respectively equipped with temperature monitoring points. Temperature data is collected through temperature sensors and uploaded to a computer through the data acquisition system.

[0013] The plurality of model tubes and the plurality of constant temperature boxes respectively simulate the near-wellbore end, the middle part of the reservoir, and the far-wellbore end of the steam injection reservoir.

[0014] The pressure control system includes a pressure gradient control pump and a pressure transmitter. The pressure gradient control pump is connected to the model tube through a pipeline. The pressure control pump controls the pressure of the model tube respectively through a constant pressure mode, so that different model tubes maintain a pressure difference.

[0015] The production system includes a gas-liquid collection and separation device, a gas-liquid thermostat, a weighing scale, and a gas metering device. The gas-liquid collection and separation device is connected to the model system to separate the gas and liquid in the output of the model system. The gas-liquid collection and separation device is located in the gas-liquid thermostat and placed on the weighing scale. The weighing scale can automatically measure the output liquid volume and is connected to the data acquisition system to transmit the output liquid volume to the data acquisition system. The gas metering device is connected to the gas-liquid collection and separation device, can automatically measure the output gas volume, and is connected to the data acquisition system to transmit the output gas volume to the data acquisition system.

[0016] The data acquisition system is connected to the injection system, the model system, and the production system to collect data such as injection volume, temperature, pressure, output liquid volume, and output gas volume.

[0017] The object of the present invention can also be achieved by the following technical measures: an experimental method for a device simulating the influence of steam injection on the physical properties of heavy oil. The experimental method for the device simulating the influence of steam injection on the physical properties of heavy oil uses a device simulating the influence of steam injection on the physical properties of heavy oil, including:

[0018] Step 1, conduct basic parameter tests. Fill the model tube with cores, set the temperature of the thermostat in the model system, and keep it constant until the temperature of the simulated reservoir is uniform.

[0019] Step 2, the injection system injects saturated oil into the model tube and keeps the model tube at a constant temperature to establish a simulated reservoir.

[0020] Step 3, adjust the temperature and pressure of the model tube, and the injection system injects water into the model tube.

[0021] Step 4, when the injection volume reaches the designed injection volume, stop injection, conduct a soaking period. After the soaking period ends, start production.

[0022] Step 5, the production system records the output gas and liquid volumes.

[0023] Step 6, when there is no more output, stop production, complete the first round of huff and puff, separate the oil and water in the output liquid, and test the physical properties of the output oil.

[0024] The object of the present invention can also be achieved by the following technical measures:

[0025] In Step 1, when conducting basic parameter tests, test the target crude oil viscosity-temperature characteristics, density, and crude oil physical property analysis in the test experimental plan.

[0026] In Step 1, select quartz sand according to the reservoir porosity to fill multiple model tubes, evacuate, saturate with water, and measure the permeability; the permeability is the same as that of the simulated target reservoir.

[0027] In step 2, load the target dehydrated crude oil into the saturated oil device, set the heating temperature of the saturated oil device to the reservoir temperature, heat the target dehydrated crude oil until it is uniform, start the injection pump to drive the injection model tube, stop the injection after the injection volume reaches the designed volume of the experimental plan, and keep the multiple model tubes at a constant temperature at the reservoir temperature for more than 48 hours.

[0028] In step 3, the number of model tubes is three. Set the temperatures of the three constant temperature boxes to the near-wellbore zone temperature, the middle reservoir temperature, and the far-end reservoir temperature respectively. The pressure gradient control pump is connected to the model tubes through pipelines. The pressure control pump controls the pressures of the model tubes respectively through the constant pressure mode to make different model tubes maintain pressure differences.

[0029] In step 3, start the injection pump and inject water into the model tubes. During the injection process, the pressure and temperature in the model always remain at the initially set temperature and pressure, so that the injected water is in the state designed in the experimental plan in the model tubes: unsaturated water or saturated water or wet steam or dry saturated steam or superheated steam.

[0030] In step 6, test the physical properties of the produced oil, including crude oil density, viscosity-temperature properties, and crude oil components.

[0031] The experimental method of the device for simulating the influence of steam injection on the physical properties of heavy oil also includes that after step 6, conduct the next round of huff and puff experiment, repeat the above steps 1-6, stop the experiment after reaching the designed number of rounds of the experiment, and conduct the physical property analysis of the produced oil. Analyze the viscosity, rheology, viscosity-temperature properties, rheology, and composition of the crude oil, etc.; through these changes, analyze the important determining factors of the physical property changes of the crude oil after steam injection, which are related to the nature of the crude oil itself, related to the external temperature and pressure, and related to the injected steam (unsaturated water or saturated water or wet steam or dry saturated steam or superheated steam). At the same time, it can also be concluded that different injected steams have different effects on the physical properties of the crude oil, and different injection methods (steam injection, steam huff and puff, steam combined huff and puff) also have different effects on the physical properties of the crude oil. According to this analysis result, optimize the development method of the heavy oil reservoir and the on-site injection parameters targeted.

[0032] The device and experimental method for simulating the influence of steam injection on the physical properties of heavy oil in the present invention are not limited to the simulation of the steam huff and puff production method, but can also be applied to steam flooding, and at the same time, the simulation of the gas-assisted steam huff and puff production method, that is, steam combined huff and puff, can be carried out to analyze the influence of the injected gas on distillation. Compared with the prior art, the present invention has the following characteristics and advantages:

[0033] 1. This device can not only simulate the steam flooding and steam huff and puff development methods, but also simulate the development methods of steam huff and puff turning to steam flooding and steam combined huff and puff;

[0034] 2. By connecting model pipes with different diameters in series, simulate the development of temperature and pressure fields at the near-wellbore area, the middle part of the reservoir, and the far end of the reservoir during the steam injection process;

[0035] 3. Obtain water vapor (unsaturated steam, saturated steam, superheated steam) by precisely controlling pressure and temperature, without the need for a steam generator;

[0036] 4. This experimental method can analyze the physical properties of crude oil after steam injection by analyzing the components of the produced gas and heavy oil during the experiment, providing a strong basis for optimizing the injection and production parameters of the steam injection recovery plan. Description of the Drawings

[0037] Figure 1 It is a schematic structural diagram of the device for simulating the influence of steam injection on the physical properties of heavy oil in a specific embodiment of the present invention;

[0038] Figure 2 It is a structural block diagram of the device for simulating the influence of steam injection on the physical properties of heavy oil in a specific embodiment of the present invention;

[0039] Figure 3 It is a schematic diagram comparing the oil production rates in different cycles of steam soaking in a specific embodiment of the present invention;

[0040] Figure 4 It is a schematic diagram comparing the water cut rates in different cycles of steam soaking in a specific embodiment of the present invention;

[0041] Figure 5 It is a schematic diagram comparing the recovery rates in different cycles of steam soaking in a specific embodiment of the present invention;

[0042] Figure 6 It is a schematic diagram comparing the oil production rates in different cycles of steam-assisted gravity drainage in a specific embodiment of the present invention;

[0043] Figure 7 It is a schematic diagram comparing the water cut rates in different cycles of steam-assisted gravity drainage in a specific embodiment of the present invention;

[0044] Figure 8 It is a schematic diagram comparing the recovery rates in different cycles of steam-assisted gravity drainage in a specific embodiment of the present invention;

[0045] In the figure, 1. Injection system; 11. Water source; 12. Injection pump; 13. Saturated oil device; 14. Valve;

[0046] 2. Model system; 21. Model pipe III; 22. Model pipe II; 23. Model pipe I; 24. Thermostatic chamber III; 25. Thermostatic chamber II; 26. Thermostatic chamber I; 27. Temperature sensor III; 28. Temperature sensor II; 28. Temperature sensor I;

[0047] 3. Pressure control system; 31. Pressure transmitter 1; 32. Pressure transmitter 2; 33. Pressure transmitter 3; 34. Pressure transmitter 4; 35. Pressure transmitter 5; 36. Pressure transmitter 6; 37. Pressure transmitter 7; 38. Pressure transmitter 8; 39. Pressure gradient control pump;

[0048] 4. Output system; 41. Gas-liquid collection and separation device; 42. Balance; 43. Automatic gas metering device; 44. Thermostatic chamber;

[0049] 5. Data acquisition system; 51. Data acquisition device; 52. Computer. Detailed implementation manners

[0050] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0051] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, and / or combinations thereof.

[0052] The present invention provides a device for simulating the influence of steam injection on the physical properties of heavy oil, including an injection system, a model system, a pressure control system, an output system, and a data acquisition system. The injection system is connected to the model system and the output system through pipelines; the pressure control system is connected to the model system through pressure transmitters; the pressure data collected by the pressure transmitters, the gas data collected by the automatic gas metering device, and the temperature detection data of the thermostatic chamber are connected to the data acquisition system through the data acquisition device and input into the computer.

[0053] The injection system is used to inject water and saturated oil into the model system, and mainly includes a water source, a saturated oil device, and an injection pump; the saturated oil device is an intermediate container, and the outer layer is equipped with heat insulation, heating, and temperature control devices. The temperature of the saturated oil device is controlled by the temperature control device and can be set manually; the temperature acquisition information is transmitted to the data acquisition system and uploaded to the computer, or can also be controlled by the computer.

[0054] The described model system includes three model tubes and three constant temperature chambers: The total effective length of the model tubes is 1800 mm, which consists of three model tubes with lengths of 600 mm and diameters of 25 mm for model tube I, 60 mm for model tube II, and 150 mm for model tube III. They are connected in the order of the smallest, medium, and largest diameters of model tube I, model tube II, and model tube III. Each model tube is independently placed in three constant temperature chambers, and the temperatures of the three constant temperature chambers are independently controlled. The pressure control system includes a pressure gradient control pump and a pressure transmitter. Pressure monitoring points are respectively provided at the inlet ends of model tube I, model tube II, and model tube III, and at the outlet end of model tube III, and pressure transmitters are installed; two pressure monitoring points are respectively provided on the bodies of model tube I and model tube II, and pressure transmitters are installed. The pressure gradient control pump is connected to the model tubes through pipelines, and the pressure control pump controls the pressures of the model tubes respectively through a constant pressure mode to keep different pressure differences in the model tubes.

[0055] The production system includes a gas-liquid collection and separation device, a constant temperature chamber, an automatic weighing balance, and a gas automatic metering device; the gas-liquid collection and separation device is in the constant temperature chamber and placed on the automatic weighing balance, which can automatically measure the output liquid volume; the gas-liquid collection and separation device is connected to the gas automatic metering device through a pipeline. The automatic weighing balance and the gas automatic metering device are connected to the data acquisition device through data lines and enter the data acquisition system. The data acquisition system includes a data acquisition device and a computer, and the data collected by the device for simulating the influence of steam injection on the physical properties of heavy oil enters the computer through the data acquisition device.

[0056] The device for simulating the influence of steam injection on the physical properties of heavy oil according to the present invention can simulate the process of steam injection into heavy oil, including the implementation processes of steam flooding and steam huff and puff. The described device for simulating the influence of steam injection on the physical properties of heavy oil simulates the near-wellbore area, the middle part of the reservoir, and the far-wellbore area of the steam injection reservoir through core tubes with different diameters; simulates the temperature and pressure changes in each part of the reservoir during the exploitation process; the generation of steam does not require a steam generator, and through precise control of pressure and temperature, the generation of steam in different states is realized, the simulation of the reservoir during the steam huff and puff process and the steam flooding process is realized, and real-time gas-liquid separation is achieved at the production end, and the amounts of the liquid and gas at the production end are collected and automatically measured.

[0057] The present invention provides an experimental method for simulating the influence of steam injection on the physical properties of heavy oil. By carrying out the process of simulating steam injection under different states, the physical property tests of the produced crude oil, gas, and remaining oil are carried out, and the physical properties of the crude oil before steam injection are compared to obtain the analysis of the influence of steam injection on the physical properties of heavy oil. Based on the development of the reservoir temperature field during multiple rounds of huff and puff steam injection, the experimental scheme is designed according to the specific production rounds on site. It is also possible to simulate the steam flooding experiment after multiple rounds of huff and puff. Three model pipes of a device for simulating the influence of steam injection on the physical properties of heavy oil are connected in series to simulate the near-wellbore reservoir, the middle reservoir, and the far-end reservoir respectively: Model pipe I simulates the temperature in the near-wellbore area (set as the steam injection temperature), Model pipe II simulates the temperature in the middle of the reservoir, and Model pipe III simulates the far end of the reservoir (set as the reservoir temperature). During the experimental process, pressure data, gas, and liquid production data are collected. Then, the produced liquid is separated into oil and water, the quantity of the produced oil, water is recorded, and the physical properties of the components of the produced oil are analyzed. By comparing the physical properties of the components of the injected oil, the changes in the physical properties of the crude oil after the action of high-temperature steam are analyzed.

[0058] The simulation of steam injection can be achieved by controlling temperature and pressure to simulate steam under different states. The steam injected into the reservoir has different states in the reservoir due to different temperatures and pressures, which are divided into unsaturated water, saturated water, wet steam, dry saturated steam, and superheated steam. The temperature is set through the constant temperature box outside the model pipe in the model system, and the pressure is adjusted and controlled to be constant by the pressure gradient control pump to ensure that the water injected into the simulated reservoir is transformed into the required steam state.

[0059] During the experimental process, the temperature and pressure of the model pipe are adjusted to obtain the corresponding steam. During the simulation of the production process, the corresponding pressure, produced liquid, and produced gas data are continuously collected to provide data support for the recovery factor of each cycle of huff and puff. The produced liquid is separated into oil and water, and the physical properties of the produced oil are analyzed to provide a favorable analysis basis for the changes in the physical properties of the crude oil after steam injection.

[0060] The following are several specific embodiments of applying the present invention

[0061] Embodiment 1

[0062] In a specific Embodiment 1 of applying the present invention, as Figure 1 and Figure 2 shown, a device for simulating the influence of steam injection on the physical properties of heavy oil includes an injection system 1, a model system 2, a pressure control system 3, a production system 4, and a data acquisition system 5. The injection system 1 includes a water source 11, a saturated oil device 12, and an injection pump 13; the injection system 1 is connected to the model system 2 through pipelines and valves.

[0063] The model system 2 includes three model pipes: model pipe III 21, model pipe II 22, and model pipe I 23, with diameters of 25 mm, 60 mm, and 150 mm respectively and a length of 600 mm. The three model pipes are connected in series and are respectively placed in incubator III 24, incubator II 25, and incubator I 26 to control the temperatures of the three model pipes respectively.

[0064] The pressure control system 3 is connected to the model system 2 through a pressure transmitter and to the data acquisition system through a data acquisition device 51. The pressure gradient control pump 39 is connected to the model system 2 through pipeline valves, and the pressure of the three model pipes of the model system 2 is adjusted in a constant pressure mode through the pressure control pump; to maintain pressure differences in different model pipes.

[0065] The pressure sensor is a pressure control system, and the temperature of the incubator is measured by a temperature sensor Figure 1 in 27, 28, 29.

[0066] For the output system 4, the gas-liquid collection and separation device 41 collects the produced liquid and gas from the model system 2 through pipelines and separates the gas and liquid simultaneously; a balance 42 is installed below the gas-liquid collection and separation device 41, which can automatically measure the mass of the produced gas and liquid and can also separate the gas and liquid; the gas-liquid collection and separation device 41 is placed inside the incubator 44, and the purpose of the incubator 44 is to ensure that the produced gas is in a gaseous state; the gas-liquid collection and separation device 41 separates the gas into the gas automatic metering device 43 through a conduit, and the purpose of the gas automatic metering device 43 is to collect and measure the produced gas; the real-time measurement data of the balance 42 and the gas automatic metering device 43 are input into the computer 52 through the data acquisition device 51. The data acquisition device 51 is mainly used to collect the pressure of the model system, the liquid and gas metering of the output system in real time, and input them into the computer 52 to form a database as the basis for experimental data analysis.

[0067] The present invention also provides an experimental method for simulating the influence of steam injection on the physical properties of heavy oil. This experimental method uses the device for simulating the influence of steam injection on the physical properties of heavy oil as described above, and this experimental method includes the following steps:

[0068] 1. Basic parameter testing: Conduct conventional crude oil property tests: crude oil viscosity-temperature characteristics, density, crude oil physical property analysis, etc. The crude oil physical property analysis includes crude oil components and rheology.

[0069] Test the viscosity-temperature characteristics, density, and crude oil physical property analysis of the target crude oil in the test experimental plan.

[0070] 2. Simulation of reservoir establishment:

[0071] (1) Core filling: Select quartz sand according to the reservoir porosity to fill model pipe I 24, model pipe II 23, and model pipe III 22, evacuate, saturate with water, and measure the permeability; the permeability is the same as that of the simulated target reservoir;

[0072] (2) Simulated reservoir temperature: The constant temperature incubators Ⅰ26, Ⅱ25, and Ⅲ24 are set to the reservoir temperature and kept at a constant temperature until the simulated reservoir temperature is uniform.

[0073] (3) Oil saturation: Load the target dehydrated crude oil into the oil saturation device, set the heating temperature of the oil saturation device to the reservoir temperature, and heat the oil until it is uniform; turn the valve 14 into the process of the oil saturation device 13, start the injection pump to drive the oil into the model pipe, stop injecting after the injection volume reaches the designed amount in the experimental plan, and close the valve 14.

[0074] (4) Constant temperature: Keep the temperature constant for more than 48 hours at the reservoir temperature in the model pipes Ⅰ23, Ⅱ22, and Ⅲ21.

[0075] 3. Steam injection experiment --- Steam soak experiment:

[0076] (1) Set the temperature of the constant temperature incubator Ⅰ26 to t1, the temperature of the constant temperature incubator Ⅱ25 to t2, and the temperature of the constant temperature incubator Ⅲ to t3. t1 corresponds to the temperature in the near-wellbore zone (set as the steam injection temperature), t2 simulates the temperature in the middle of the reservoir, and t3 simulates the far end of the reservoir (set as the reservoir temperature). The pressure gradient control pump 39 controls the pressure in the model pipes Ⅰ23, Ⅱ22, and Ⅲ21.

[0077] (2) Water injection: Open the valve 14, start the injection pump 12, inject water into the model, and keep the pressure and temperature in the model at the initially set temperature and pressure during the injection process, so that the injected water is in the state designed in the experimental plan in the model: unsaturated water or saturated water or wet steam or dry saturated steam or superheated steam.

[0078] (3) Soak the well: When the injection volume reaches the designed injection volume, stop injecting and soak the well.

[0079] (4) Stop soaking the well after the soak time reaches the designed time and start production.

[0080] (5) Production process: Record the temperature and pressure data during the production process. The production system separates the produced gas into the gas automatic metering device 43 through the gas-liquid separation device 41, and records the amounts of the produced gas and liquid.

[0081] (6) When the produced liquid (gas) stops being produced, stop production, complete the first round of soak, then separate the oil and water in the produced liquid, and test the physical properties of the produced oil: including crude oil density, viscosity-temperature properties, and crude oil components.

[0082] (7) Conduct the next round of soak experiment and repeat the above steps 1-6.

[0083] (8) Stop the experiment after reaching the designed number of rounds.

[0084] 4. Analysis of the Physical Properties of Produced Oil

[0085] Through the analysis of the changes in the physical properties of crude oil during the injection of steam in different states, conclusions are drawn. Analyze the viscosity-temperature properties, rheology, composition, etc. of crude oil; through these changes, analyze the important determining factors for the changes in the physical properties of crude oil after steam injection, which are related to the nature of the crude oil itself, the external temperature and pressure, and the injected steam (unsaturated water or saturated water or wet steam or dry saturated steam or superheated steam). At the same time, it can also be concluded that different injected steams have different effects on the physical properties of crude oil, and different injection methods (steam injection, steam huff and puff, steam combined huff and puff) also have different effects on the physical properties of crude oil. According to this analysis result, optimize the development method of heavy oil reservoirs and on-site injection parameters targeted.

[0086] Example 2

[0087] Taking a steam huff and puff heavy oil reservoir in Shengli Oilfield as an example, the influence of steam injection on the physical properties of heavy oil is clarified through an experimental method for simulating the influence of steam injection on the physical properties of heavy oil.

[0088] According to the basic parameter test described in Step 1, test the basic physical properties of the target crude oil in the test experimental plan. The viscosity at 60°C is 5000 mPa·s.

[0089] According to the simulated reservoir establishment described in Step 2, first fill the model tube. Select quartz sand with different particle sizes for filling according to the reservoir physical properties, and then evacuate, saturate with water, and measure the permeability. The porosity of Model Tube Ⅰ24 is 35.4%, and the permeability is 9825 mD. The porosity of Model Tube Ⅱ23 is 32%, and the permeability is 1845 mD. The porosity of Model Tube Ⅲ22 is 31%, and the permeability is 1801 mD; the permeability is close to the simulated target reservoir. Secondly, conduct temperature simulation. Set the constant temperature boxes Ⅰ26, Ⅱ25, and Ⅲ24 to the reservoir temperature of 60°C, so that the temperatures at different positions are close. Finally, saturate with oil. Load the target dehydrated crude oil into the oil saturation device 13, set the heating temperature of the oil saturation device to the reservoir temperature of 60°C, and heat the oil evenly; turn the valve 14 into the process of the oil saturation device 13, start the injection pump to drive and inject into the model tube. Stop injecting after the injection volume reaches the designed amount in the experimental plan, and close the valve 14. Model Tubes Ⅰ23, Ⅱ22, and Ⅲ21 are kept at a constant temperature for more than 48 hours at the reservoir temperature.

[0090] According to the steam injection huff and puff experiment described in Step 3, the temperatures of constant temperature incubators Ⅰ26, Ⅱ25, and Ⅲ24 are set to 300°C, 160°C, and 60°C respectively. The pressure gradient control pump 39 controls the pressures of model pipes Ⅰ23, Ⅱ22, and Ⅲ21 to be 14, 12, and 10 MPa respectively. Open valve 14, start injection pump 12, and inject water into the model. When the pressure reaches 14 MPa, stop injection and soak the well for 2 h. After the soaking time reaches the designed time, stop soaking and start production. The production system separates the produced gas into the gas automatic metering device 43 through the gas-liquid separation device 41, and records the amounts of produced gas and liquid. When gas and liquid no longer flow out, stop production to complete the first round of huff and puff. Then separate the oil and water in the produced liquid and test the physical properties of the produced oil, including crude oil density, viscosity-temperature property, and crude oil components. Conduct the next round of huff and puff experiment and repeat the above steps 1-6. Stop the experiment after reaching the 4th round, analyze the oil production rate, water cut, and recovery rate in different rounds, as Figure 3 , Figure 4 , Figure 5 shown.

[0091] According to the physical property analysis of the produced oil described in Step 3, conduct physical property analysis on the crude oil samples collected in 4 rounds. The analysis results are shown in Table 1.

[0092] It can be seen from the oil production amount, water cut, and recovery rate curves in different cycles that, as Figure 3 , Figure 4 , Figure 5 shown, the cumulative oil production amount in the first cycle of steam huff and puff reaches a maximum of 96.72 ml, which is more than twice that of 42.84 ml in the fourth cycle. The recovery rate reaches 3.26%, and the effect is relatively ideal. After the well is opened for production in the first cycle of steam huff and puff, the viscosity of the crude oil decreases significantly under the heating of the steam. Therefore, the oil production rate rapidly increases to 15 ml / MPa, and the oil production rate is relatively fast. At this time, the water cut is also relatively low, with an average water cut of 49.16%. However, with the progress of exploitation, the oil production rate drops to 12 MPa, which generally decreases compared with the previous cycle. The oil production rate at the end of huff and puff is 1.83 ml / MPa, and the average water cut increases to 62.54%. The amount of water begins to gradually increase, and the produced water reaches 142.26 ml. In the third cycle, the heat of the steam gradually dissipates and cannot fully heat the crude oil. The peak value of the oil production rate drops to 8.36 ml / MPa. The oil production rate at the end of the cycle huff and puff is 1.12 ml / MPa, and the recovery rate also drops to 17.9%. At this time, the produced water amount reaches 192.14 ml, and the average water cut is 74.35%. With the exploitation of the huff and puff cycle, the peak value of the oil production rate gradually drops to 7.05 ml / MPa, the recovery rate drops to 14.77%, and the average water cut is nearly 80%.

[0093] It can be seen from the experimental results that the oil production by steam stimulation decreases with the decrease of pressure. As the production cycle progresses, the oil production continuously decreases. The oil production in the third and fourth cycles is low, while the water cut is high. It can be concluded that during the third and fourth rounds of steam stimulation, the available heavy oil saturation significantly decreases compared with the first two cycles.

[0094] It can be seen from the molar ratios of the four components of crude oil samples in different rounds that, as shown in Table 1, the contents of heavy components such as resins and asphaltenes in the crude oil sample of the first round are relatively low, while the contents of light components such as aromatic hydrocarbons and saturated hydrocarbons are relatively high. After 4 rounds, the content of heavy components in the crude oil significantly increases, and the content of light components decreases, indicating that during the process of developing heavy oil by multi-round steam stimulation, light components are preferentially produced, and components such as resins and asphaltenes accumulate in the reservoir.

[0095] Table 1 Molar ratios of the four components of crude oil samples in different rounds

[0096]

[0097]

[0098] Example 3

[0099] Taking a heavy oil reservoir with thermal recovery in Shengli Oilfield as an example, the effects of steam injection combined with CO2 injection on the physical properties of heavy oil and oil recovery factor were studied through simulating steam injection combined huff and puff.

[0100] According to the basic parameter test described in Step 1, the basic physical properties of the target crude oil in the test experimental plan were tested, and the viscosity at 60 °C was 12036 mPa·s.

[0101] According to the simulated reservoir establishment described in Step 2, first, the model tube was filled. Quartz sands with different particle sizes were selected and filled according to the reservoir physical properties, and then vacuum pumping, water saturation, and permeability measurement were carried out. The porosity of Model Tube Ⅰ24 was 35.4%, and the permeability was 13425 mD; the porosity of Model Tube Ⅱ23 was 32%, and the permeability was 1247 mD; the porosity of Model Tube Ⅲ22 was 31%, and the permeability was 1375 mD; the permeability was close to the simulated target reservoir. Secondly, temperature simulation was carried out. The constant temperature boxes Ⅰ26, Ⅱ25, and Ⅲ24 were set to the reservoir temperature of 60 °C, and the temperatures at different positions were close. Finally, oil saturation was carried out. The target dehydrated crude oil was loaded into the oil saturation device 13, and the heating temperature of the oil saturation device was set to the reservoir temperature of 60 °C, and the oil was heated evenly; the valve 14 was transferred to the oil saturation device 13 process, the injection pump was started to drive and inject into the model tube, and the injection was stopped after the injection volume reached the designed amount of the experimental plan, and the valve 14 was closed. Model Tubes Ⅰ23, Ⅱ22, and Ⅲ21 were kept at a constant temperature for more than 48 hours at the reservoir temperature.

[0102] According to the steam injection huff and puff experiment described in Step 3, the temperatures of constant temperature incubators Ⅰ26, Ⅱ25, and Ⅲ24 are set to 350°C, 180°C, and 60°C respectively. The pressure gradient control pump 39 controls the pressures of model pipes Ⅰ23, Ⅱ22, and Ⅲ21 to be 14, 12, and 10 MPa respectively. Open valve 14, start injection pump 12, and inject water into the model. During the injection process, the pressure and temperature in the model always remain at the initially set temperature and pressure. When the injection volume reaches the designed injection volume, stop injection and soak the well for 2 h. After the soaking time reaches the designed time, stop soaking and start production. The production system separates the produced gas into the gas automatic metering device 43 through the gas-liquid separation device 41, and records the amounts of produced gas and liquid. When gas and liquid no longer flow out, stop production to complete the first round of huff and puff. Then separate the oil and water in the produced liquid and test the physical properties of the produced oil, including crude oil density, viscosity-temperature property, and crude oil components. Conduct the next round of huff and puff experiment and repeat the above steps 1-6. Different from the first round, in the second round, CO2 is injected instead. When the injection pressure reaches 14 MPa, stop injection, soak the well for 4 h, and then repeat the aforementioned experimental steps. Stop the experiment after reaching the fourth round, analyze the oil production rate, water cut, and recovery rate of different rounds, as Figure 6 , Figure 7 , Figure 8 shown.

[0103] According to the physical property analysis of the produced oil described in Step 3, conduct physical property analysis on the crude oil samples collected in 4 rounds. The analysis results are shown in Table 2.

[0104] From the oil production amount, water cut, and recovery rate curves of different cycles of steam combined huff and puff, as Figure 6 , Figure 7 , Figure 8 shown, in the first round of steam injection huff and puff thermal recovery, the oil production amount is as high as 117.85 ml, the highest oil production rate is 18.69 ml / MPa, and the recovery rate is 3.51%. The recovery rate is the highest and the effect is relatively remarkable. With the combined injection of CO2, the oil production rate reaches the maximum of 12.35 ml / MPa since the well is opened for production, and the average water cut is only 14.353%. The water cut is generally not high, but the recovery degree reaches nearly 22.18%. When cold production huff and puff ends and steam injection huff and puff is switched, the oil production rate drops from 15.16 MPa to 2.36 MPa, and the average water cut also increases to 64.3%. The recovery rate is nearly 4% higher than that of the previous cycle of cold production. Finally, when switching to CO2 combined huff and puff, the maximum oil production rate is 9.18 ml / MPa, the oil production amount is 52.89 ml, which is about 50% of that in the first cycle, and the average water cut also drops to 12.24. The lowest recovery rate is only 1.45%.

[0105] After the steam soak production ended, hot water with a temperature higher than that of the sand-packed tube was left, increasing the temperature of the model. When injecting CO2, it first replenished the formation energy, which was also the reason for the high production rate at the beginning of production. During the first cycle of cold production, part of the CO2 dissolved in the crude oil, reducing the viscosity of the crude oil and replenishing the formation energy. The cyclic production of the hot production after cold production was larger than that of the simple steam soak in the same stage. Since no water injection was carried out during cold production, the water cut was extremely low, which was also the irreducible water in the previous cycle and was produced during the cold production stage, reducing the water cut increase rate in the next stage. This was also the reason why the water cut of the hot production in the next stage was lower than that of the simple steam soak after the cold production cycle.

[0106] It can be seen from the molar ratios of the four-component contents of the crude oil samples in different cycles that, as shown in Table 2, the experimental results were similar to those of steam soak. For the crude oil sample in the first cycle, the contents of heavy components such as resin and asphaltene were less, and the contents of light components such as aromatic hydrocarbons and saturated hydrocarbons were relatively more. After 4 cycles, the contents of heavy components in the crude oil increased significantly, while the contents of light components decreased, indicating that during the development of heavy oil by multi-cycle soak, light components were preferentially produced, and components such as resin and asphaltene accumulated in the reservoir. The difference was that the degree of reservoir utilization of the steam / CO2 combined soak was greater than that of the steam soak, mainly reflected in the contribution value of the hot production after cold production, indicating that part of the water produced by the CO2 combined soak promoted the utilization of steam in the next stage. At the same time, it also indicated that a certain amount of gas remained in the formation to maintain the fluctuation of the formation elastic energy. In short, the effect of the heavy oil steam / CO2 combined soak was better than that of the simple steam soak.

[0107] Table 2 Cumulative production ratio table of components in different cycles

[0108] Period Asphaltene Resin Aromatic hydrocarbon Saturated hydrocarbon 1 0.05 0.055 0.185 0.155 2 0.055 0.09 0.155 0.13 3 0.078 0.15 0.13 0.1 4 0.085 0.18 0.08 0.065

[0109] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

[0110] Except for the technical features described in the specification, they are all known technologies to those skilled in the art.

Claims

1. An apparatus for simulating the influence of steam injection on the physical properties of heavy oil, characterized in that, The device for simulating the influence of steam injection on the physical properties of heavy oil includes an injection system, a model system, a pressure control system, a production system, and a data acquisition system. The injection system is connected to the model system and injects water or oil into the model system. The model system includes multiple model tubes. The pressure control system is connected to the model system and the data acquisition system, controls the pressure of the multiple model tubes in the model system through a constant pressure mode to form different pressure gradients, and transmits pressure information to the data acquisition system. The production system is connected to the model system and separates the produced substances in the model system into gas and liquid and measures the gas and liquid separately.

2. The apparatus for simulating the influence of steam injection on the physical properties of heavy oil according to claim 1, characterized in that, The injection system includes a water source, a saturated oil device, and an injection pump. The water source is connected to the injection pump through a pipeline. The injection pump is connected to the model system through a pipeline and a valve. When the valve is opened, the injection pump injects water into the model system through the pipeline. When saturating the oil, the process is switched through the valve. The water source is connected to the injection pump through a pipeline. The injection pump is connected to the saturated oil device through a pipeline. The saturated oil device is connected to the model system through a pipeline. Water is injected into the bottom of the saturated oil device through the injection pump, and the oil in the saturated oil device is driven to be injected into the model system through the pipeline.

3. The apparatus for simulating the influence of steam injection on the physical properties of heavy oil according to claim 2, characterized in that the saturated oil device is an intermediate container, with heat insulation, heating, and temperature control devices installed on the outer layer. The temperature of the saturated oil device is controlled by the temperature control device and can be set manually; the temperature control device collects temperature information and transmits it to the data acquisition system for uploading to the computer, or it can also be controlled by the computer.

4. The apparatus for simulating the influence of steam injection on the physical properties of heavy oil according to claim 1, characterized in that, The model system includes multiple model tubes and multiple constant temperature boxes corresponding to each model tube. The multiple model tubes are respectively placed into the corresponding constant temperature boxes. The multiple model tubes are connected in ascending order of diameter. Pressure monitoring points are respectively arranged at the inlet end, outlet end, and middle of each model tube and monitored by pressure sensors. Temperature monitoring points are arranged in the constant temperature boxes and monitored by temperature sensors. The monitoring data is uploaded to a computer through the data acquisition system.

5. The apparatus for simulating the influence of steam injection on the physical properties of heavy oil according to claim 4, characterized in that, For the multiple model tubes and the multiple constant temperature boxes, the multiple model tubes have the same length but different diameters and respectively simulate the near-wellbore area, the middle part of the reservoir, and the far-wellbore area of the steam injection reservoir.

6. The apparatus for simulating the influence of steam injection on the physical properties of heavy oil according to claim 4, characterized in that, The pressure control system includes a pressure gradient control pump and a pressure transmitter. The pressure transmitter measures the pressure inside the model system. The pressure gradient control pump is connected to the multiple model tubes through a pipeline. The pressure gradient control pump controls the pressures of the multiple model tubes respectively through a constant pressure mode to keep pressure differences among different model tubes.

7. The apparatus for simulating the influence of steam injection on the physical properties of heavy oil according to claim 1, characterized in that, The production system includes a gas-liquid collection and separation device, a gas-liquid constant temperature box, a weighing scale, and a gas metering device. The gas-liquid collection and separation device is connected to the model system and separates the produced substances in the model system into gas and liquid. The gas-liquid collection and separation device is located in the gas-liquid constant temperature box and placed on the weighing scale. The weighing scale can automatically measure the output liquid volume and is connected to the data acquisition system to transmit the output liquid volume to the data acquisition system. The gas metering device is connected to the gas-liquid collection and separation device, can automatically measure the output gas volume, and is connected to the data acquisition system to transmit the output gas volume to the data acquisition system.

8. The apparatus for simulating the influence of steam injection on the physical properties of heavy oil according to claim 1, characterized in that, The data acquisition system is connected to the injection system, the model system, and the production system and collects data such as injection volume, temperature, pressure, output liquid volume, and output gas volume.

9. An experimental method for the apparatus for simulating the influence of steam injection on the physical properties of heavy oil, characterized in that, The experimental method of the device for simulating the influence of steam injection on the physical properties of heavy oil adopts the device for simulating the influence of steam injection on the physical properties of heavy oil described in claim 1, including: Step 1, conduct basic parameter tests. Fill the model tube with cores, set the temperature of the constant temperature box in the model system, and keep it constant until the temperature of the simulated reservoir is uniform. Step 2, the injection system injects saturated oil into the model tube and keeps the model tube at a constant temperature to establish a simulated reservoir. Step 3, adjust the temperature and pressure of the model tube, and the injection system injects water into the model tube. Step 4, when the injection volume reaches the designed injection volume, stop injection, perform a soaking period, and start production after the soaking period ends. Step 5, the production system records the production volume of gas and liquid. Step 6, when there is no more production, stop production, complete the first round of huff and puff, separate the oil and water in the produced liquid, and test the physical properties of the produced oil.

10. The experimental method for the apparatus for simulating the influence of steam injection on the physical properties of heavy oil according to claim 9, characterized in that, In step 1, when conducting basic parameter tests, test the viscosity-temperature characteristics, density, and crude oil physical property analysis of the target crude oil in the test experimental plan.

11. The experimental method for the apparatus for simulating the influence of steam injection on the physical properties of heavy oil according to claim 9, characterized in that, In step 1, select quartz sand according to the reservoir porosity to fill multiple model tubes, evacuate, saturate with water, and measure the permeability; the permeability is the same as that of the simulated target reservoir.

12. The experimental method for the apparatus for simulating the influence of steam injection on the physical properties of heavy oil according to claim 9, characterized in that, In step 2, load the target dehydrated crude oil into the saturated oil device, set the heating temperature of the saturated oil device to the reservoir temperature, heat the target dehydrated crude oil evenly, start the injection pump to drive and inject into the model tube, stop injection after the injection volume reaches the designed volume of the experimental plan, and keep multiple model tubes at a constant temperature at the reservoir temperature for more than 48 hours.

13. The experimental method for the apparatus for simulating the influence of steam injection on the physical properties of heavy oil according to claim 9, characterized in that,In step 3, the number of model tubes is three. Set the temperatures of the three constant temperature boxes to the temperature of the near-well zone, the middle of the reservoir, and the far end of the reservoir respectively. The pressure gradient control pump is connected to the model tube through a pipeline, and the pressure control pump controls the pressure of the model tube through a constant pressure mode respectively to keep different model tubes with pressure differences.

14. The experimental method of the device for simulating the influence of steam injection on the physical properties of heavy oil according to claim 9, characterized in that, In step 3, start the injection pump and inject water into the model tube. During the injection process, the pressure and temperature in the model always maintain the initially set temperature and pressure, so that the injected water is in the state designed in the experimental plan in the model tube: unsaturated water or saturated water or wet steam or dry saturated steam or superheated steam.

15. The experimental method of the device for simulating the influence of steam injection on the physical properties of heavy oil according to claim 9, characterized in that, In step 6, testing the physical properties of the produced oil includes crude oil density, viscosity-temperature properties, and crude oil components.

16. The experimental method of the device for simulating the influence of steam injection on the physical properties of heavy oil according to claim 9, characterized in that, The experimental method of the device for simulating the influence of steam injection on the physical properties of heavy oil also includes, after step 6, conducting the next round of huff and puff experiment, repeating the above steps 1-6, stopping the experiment after reaching the designed number of rounds of the experiment, conducting the physical property analysis of the produced oil, analyzing the viscosity-temperature properties, rheology, and composition of the crude oil; through these changes, analyze the important determining factors of the physical property changes of the crude oil after steam injection, which are related to the nature of the crude oil itself, the external temperature and pressure, and the injected steam; at the same time, it can also be concluded that different injected steams have different effects on the physical properties of the crude oil, and different injection methods also have different effects on the physical properties of the crude oil; according to this analysis result, optimize the development method of heavy oil reservoirs and on-site injection parameters targeted.

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