An experimental apparatus and quantitative evaluation method for CO2 deposition characteristics of asphaltene-containing crude oil.

Abstract

This invention belongs to the technical field of oil physical property testing equipment, and provides an experimental device and quantitative evaluation method for the deposition characteristics of asphaltene-containing crude oil during CO2 injection. The experimental device includes a first water injection pump, a CO2 intermediate container, a core holder, a vertical test section, a horizontal test section, a gas-liquid separator, and a gas flow meter, connected sequentially end-to-end. The bottom of the core holder is connected to a second water injection pump. Both the vertical and horizontal test sections include pressure-resistant glass pipelines and annular heating blocks. The annular heating blocks are partially closed cylindrical rings that surround the pressure-resistant glass pipelines and provide observation positions. Each annular heating block contains several parallel heating resistance wires, forming a gradient temperature field through these blocks. This invention can accurately simulate the asphaltene deposition and oil quality changes during CO2 displacement and extraction of asphaltene-containing crude oil; and through physical model experiments combined with numerical model analysis, it can quickly and quantitatively clarify the asphaltene deposition and precipitation patterns during crude oil CO2 injection.

Description

Technical Field

[0001] This invention belongs to the technical field of oil physical property testing equipment, specifically relating to an experimental device and quantitative evaluation method for CO2 deposition characteristics of asphalt-containing crude oil. Background Technology

[0002] Asphaltene can be further classified into pentane asphaltene, heptane asphaltene, coal tar pitch, and shale asphaltene, among others, with significant compositional differences depending on the production location and reservoir environment. Asphaltene deposition is a major problem in oil and gas extraction, causing reservoir damage, sharp production declines, wellbore blockage, and well shutdowns. Asphaltene has a complex structure containing various heteroatoms with varying heteroatom contents, although the C and H content is relatively stable. While the heteroatom content in asphaltene is not high, it significantly influences the properties of petroleum components and depositional characteristics.

[0003] Chinese patent application CN202020189332X discloses an experimental device for simulating the wax deposition characteristics and pipe flow characteristics of waxy crude oil. The device includes an oil storage tank, a variable frequency oil pump, a test section, and a flow meter, connected sequentially to form a loop. The oil storage tank and the test section are located in separate constant temperature water baths, used to adjust their temperatures. Multiple transparent acrylic tubes of varying diameters are used to simulate the wax deposition process during diameter changes.

[0004] However, in the process of implementing the technical solution in the embodiments of this application, the inventors of this application discovered that the technical solution of the patent application has at least the following technical problems:

[0005] (1) Crude oil contains a lot of asphaltenes. This device is only suitable for experiments on the deposition of waxy crude oil. After CO2 is injected into the formation, it will promote the deposition of asphaltenes in the crude oil during the mixing process. The deposited asphaltenes are prone to deposition in the wellbore due to gravity, friction and other effects, which will cause wellbore blockage and a decrease in oil production. The experimental device in this patent cannot accurately simulate the process of crude oil containing sediment flowing in the wellbore.

[0006] (2) The experimental device in this patent does not include the core part, which means it cannot accurately simulate the entire oil production process and cannot effectively characterize the production decline caused by asphalt deposition.

[0007] (3) The experimental device in this patent uses water bath heating throughout the test section, which cannot effectively characterize the temperature difference at different depths of the wellbore, and is not conducive to reflecting the true situation of asphalt deposition. Summary of the Invention

[0008] This invention aims to solve at least one technical problem existing in the background art, and provides an experimental device and quantitative evaluation method for the deposition characteristics of asphaltene-containing crude oil during CO2 injection. It can accurately simulate the asphaltene deposition and oil quality changes of asphaltene-containing crude oil during CO2 displacement and production. By adopting a segmented modular heating method, it more realistically simulates the temperature environment inside the wellbore (i.e., the temperature change with depth). Furthermore, by using a partially enclosed cylindrical heating block to wrap the pressure-resistant glass pipeline, observation positions can be reserved, allowing for a more intuitive observation of the asphaltene deposition within the pipeline. In addition, by storing the physical model experimental data in digital modeling software and directly retrieving and applying it later, the asphaltene deposition and precipitation patterns during CO2 injection of crude oil in corresponding reservoir types can be quickly and quantitatively determined. This enables rapid comprehensive analysis of data from different reservoirs, clarifies the asphaltene deposition risk during CO2 injection in different reservoir blocks, and provides a basis and support for the research and application of improved oil recovery technologies.

[0009] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0010] An experimental device for CO2 injection deposition characteristics of asphalt-containing crude oil includes a first water injection pump, a CO2 intermediate container, a core holder, a vertical test section, a horizontal test section, a gas-liquid separator, and a gas flow meter connected in sequence. The bottom of the core holder is connected to the second water injection pump.

[0011] Both the vertical and horizontal test sections include a pressure-resistant glass tube and several annular heating blocks connected end to end. The number of annular heating blocks in both sections can be set to be the same or different as needed. Each annular heating block is a partially closed ring-shaped cylindrical structure that wraps around the pressure-resistant glass tube and leaves an observation position.

[0012] Each annular heating block contains several parallel heating resistance wires to provide a set temperature to the pressure-resistant glass pipeline, and forms a gradient temperature field through several annular heating blocks connected end to end.

[0013] Furthermore, the annular heating block also includes a stainless steel shell and a temperature sensor mounted on the stainless steel shell. The heating resistance wires are evenly distributed in a ring inside the stainless steel shell. The heating resistance wires and the temperature sensor are respectively connected to the temperature controller via signal lines. The temperature controller changes the temperature and the rate of temperature rise by changing the number of parallel heating resistance wires connected to the circuit. Heating stops when the set temperature is reached, thus achieving closed-loop temperature control.

[0014] Furthermore, water is injected into the interior of the stainless steel outer shell, in the gap surrounding the heating resistance wire; the heating resistance wire is a waterproof heating rod.

[0015] Furthermore, the pressure-resistant glass pipeline of the vertical test section is a vertical pressure-resistant glass pipeline, and the periphery of the vertical pressure-resistant glass pipeline is wrapped with three sets of annular heating blocks connected end to end.

[0016] Furthermore, the pressure-resistant glass pipeline of the horizontal test section is a horizontal pressure-resistant glass pipeline, and the outer periphery of the horizontal pressure-resistant glass pipeline is wrapped with a set of annular heating blocks, and the diameter of the horizontal pressure-resistant glass pipeline is larger than that of the vertical pressure-resistant glass pipeline.

[0017] Furthermore, the first water injection pump, CO2 intermediate container, core holder, vertical test section, horizontal test section, gas-liquid separator and gas flow meter are all connected end to end by high-pressure pipelines; a constant temperature chamber is set around the core holder.

[0018] Furthermore, both ends of the pressure-resistant glass pipeline are connected to the high-pressure pipeline via elastic sleeves and adapters, with the elastic sleeves located between the ends of the pressure-resistant glass pipeline and the adapters.

[0019] Furthermore, the core holder includes a rectangular cavity structure consisting of a stainless steel pressure-resistant outer shell and an inner rubber sleeve, with the core placed inside the rubber sleeve; the left and right sides of the stainless steel pressure-resistant outer shell are respectively provided with a left threaded connection hole and a right threaded connection hole; the left threaded connection hole is a carbon dioxide injection port, and the right threaded connection hole is an outlet for the produced well fluid.

[0020] Furthermore, the bottom of the stainless steel pressure-resistant housing is provided with a bottom threaded connection hole; the bottom threaded connection hole is connected to the second water injection pump through a high-pressure pipeline.

[0021] Furthermore, the bottom of the gas-liquid separator is marked with graduations for measuring the volume of extracted oil and the volume of asphalt deposits; the outlet of the gas-liquid separator is connected to a gas meter for measuring the CO2 content.

[0022] Furthermore, each annular heating block is a three-quarter ring cylinder.

[0023] In addition, the present invention also provides a quantitative evaluation method for the CO2 injection deposition characteristics of asphalt-containing crude oil, using any of the above-mentioned experimental devices for CO2 injection deposition characteristics of asphalt-containing crude oil. The experimental device includes a first water injection pump, a CO2 intermediate container, a core holder, a vertical test section, a horizontal test section, a gas-liquid separator, and a gas flow meter connected end to end in sequence. The bottom of the core holder is connected to the second water injection pump.

[0024] The method includes:

[0025] Step S01: The first water injection pump injects water into the bottom of the intermediate container to form pressure. After reaching the simulated formation pressure, the CO2 in the intermediate CO2 container flows into the core holder through the high-pressure pipeline under pressure.

[0026] Step S02: The core holder contains a core. The second water injection pump injects water into the cavity of the core holder to form water pressure to simulate formation pressure. By injecting CO2 and water, the process of CO2 interacting with asphalt-containing crude oil in the formation during oil extraction is simulated.

[0027] Step S03: The pressure-resistant glass tube of the vertical test section is a vertical pressure-resistant glass tube, and the outer perimeter of the vertical pressure-resistant glass tube is wrapped with 3 sets of annular heating blocks connected end to end; the pressure-resistant glass tube of the horizontal test section is a horizontal pressure-resistant glass tube, and the outer perimeter of the horizontal pressure-resistant glass tube is wrapped with a set of annular heating blocks, and the diameter of the horizontal pressure-resistant glass tube is larger than that of the vertical pressure-resistant glass tube;

[0028] The annular heating block has a partially closed annular cylindrical structure and contains heating resistance wires and water. Each annular heating block is wrapped around a pressure-resistant glass tube. The water is heated by the heating resistance wires, thereby heating the glass tube surrounding it. The unwrapped glass tube portion is used to observe the deposition conditions inside the glass tube.

[0029] Step S04: The gas-liquid separator separates the crude oil and its carried asphalt from the product material;

[0030] Step S05: The gas meter measures the CO2 carried out by the oil;

[0031] Step S06: Store the experimental data on the precipitation points and amounts of asphaltene deposits in relation to temperature and pressure changes in the PVTSim software. Subsequently, for different reservoir types, directly call the experimental data of the corresponding reservoirs pre-stored in the PVTSim software to clarify the pattern of asphaltene precipitation points and amounts in relation to temperature and pressure changes in the corresponding reservoirs.

[0032] Furthermore, each annular heating block is a three-quarter ring cylinder, wrapped around a pressure-resistant glass tube; the annular heating block also includes a stainless steel shell and a temperature sensor mounted on the stainless steel shell, and the heating resistance wires are evenly distributed in parallel inside the stainless steel shell; the heating resistance wires and the temperature sensor are respectively connected to the temperature controller via signal lines.

[0033] Furthermore, the temperature sensor built into the annular heating block returns the temperature of the annular heating block to the temperature controller in real time. The temperature controller changes the temperature and the rate of temperature rise by changing the number of parallel heating resistance wires connected to the circuit. Heating stops when the set temperature is reached, thus achieving closed-loop temperature control.

[0034] Furthermore, the two sets of pressure-resistant glass pipelines with different diameters in the vertical test section and the horizontal test section are used to simulate the wellbore and surface pipelines during the crude oil recovery process, respectively; the vertical pressure-resistant glass pipeline is used to simulate the flow of asphalt-containing crude oil in the wellbore, and the horizontal pressure-resistant glass pipeline is used to simulate the flow of asphalt-containing crude oil in the surface pipeline after extraction.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] (1) Existing technologies study the deposition of asphaltenes in crude oil by observing and collecting data on-site, and observing the deposition in the laboratory by injecting CO2 into asphaltenes-containing crude oil to obtain the deposition characteristics of crude oil. However, this technology cannot reflect the impact of asphaltenes deposition on the recovery rate. This is because the CO2 injected on-site causes some asphaltenes to precipitate after contacting crude oil in the formation, which then blocks some pore throats and dominant seepage channels in the reservoir, making it impossible for crude oil to flow smoothly into the wellbore. In contrast, this invention first saturates the prepared asphaltenes-containing crude oil in the core, and then injects CO2 into the core to simulate the process of gas driving crude oil in the formation and the reservoir damage and recovery rate reduction caused by asphaltenes precipitation during the oil production process. This invention realizes the simulation of the entire process of CO2-driven asphaltenes-containing crude oil recovery.

[0037] (2) The experimental apparatus of the present invention can accurately simulate the asphaltene deposition and oil quality changes of crude oil containing asphaltene during CO2 displacement and extraction. Another factor affecting the final recovery rate is that asphaltene in crude oil will deposit in the wellbore due to temperature and pressure changes, making it impossible to extract crude oil smoothly. The existing patent application CN202020189332X uses water bath heating of glass pipelines, which cannot accurately simulate the influence of temperature changes and gravity on asphaltene deposition during CO2 displacement of crude oil containing asphaltene. The present invention achieves segmented heating of vertical pressure-resistant glass pipelines by combining heating modules to form a temperature gradient, which can more accurately reflect the influence of temperature changes on asphaltene deposition in the wellbore. The horizontal pressure-resistant glass pipeline simulates the process of crude oil flowing from the wellhead to the storage tank. During this process, due to temperature changes and gravity, crude oil cannot completely carry the precipitated asphaltene, causing asphaltene to deposit at the bottom of the horizontal pipeline. This can accurately simulate the influence of gravity on the deposition characteristics of crude oil containing asphaltene during CO2 displacement.

[0038] (3) The existing patent application CN202020189332X heats the glass tube in a water bath and observes the deposition inside the glass tube through the water surface. However, this technology cannot accurately and clearly observe the asphalt deposition process and deposition status due to the refraction of the water surface and the thickness of the pressure-resistant glass tube. The experimental device of the present invention improves the immersion water bath heating method used in the traditional experimental method. It uses a partially closed annular cylindrical heating block to wrap around the pressure-resistant glass tube and leaves an observation position, which can clearly and intuitively observe the asphalt deposition status inside the pressure-resistant glass tube.

[0039] (4) The method provided by this invention for quantitatively evaluating the precipitation points and amounts of asphaltene deposits during CO2 injection of crude oil stores experimental data on the precipitation points and amounts of asphaltene deposits with temperature and pressure changes in PVTSim software. Subsequently, for different reservoir types, the experimental data of the corresponding reservoirs pre-stored in PVTSim software can be directly called, which can quickly and quantitatively clarify the law of asphaltene precipitation points and amounts with temperature and pressure changes in the corresponding reservoirs. By storing the physical model experimental data in the numerical model software and directly retrieving and applying it in the future, the precipitation law of asphaltene deposits during CO2 injection of crude oil of the corresponding reservoir type can be quickly and quantitatively clarified, and the comprehensive analysis of data of different reservoirs can be quickly realized. The risk of asphaltene deposition during CO2 injection of different reservoir blocks can be clarified, providing a basis and support for the research and promotion of improved oil recovery technology. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the overall structure of the experimental apparatus according to an embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of the cross-sectional structure of the annular heating block enclosing the glass pipeline according to an embodiment of the present invention;

[0042] Figure 3 This is a perspective structural diagram of the annular heating block according to an embodiment of the present invention;

[0043] Figure 4 This is a schematic diagram of the core holder according to an embodiment of the present invention;

[0044] Figure 5 This is a schematic diagram of the structure of a pressure-resistant glass pipeline;

[0045] The markings in the diagram are as follows: 1. First water injection pump; 2. High-pressure pipeline; 3. CO2 intermediate container; 4. Core holder; 5. Pressure gauge; 6. Annular heating block; 7. Horizontal pressure-resistant glass pipeline; 8. Gas-liquid separator condenser; 9. Gas meter; 10. Temperature controller; 11. Vertical pressure-resistant glass pipeline; 12. Horizontal pressure-resistant glass pipeline; 13. Constant temperature chamber; 14. Second water injection pump; 15. Signal line; 111. Elastic rubber sleeve; 112. Adapter; 411. Stainless steel pressure-resistant outer shell; 412. Rubber sleeve; 413. Left threaded connection hole; 414. Right threaded connection hole; 415. Bottom threaded hole; 416. Core; 611. Temperature sensor; 612. Heating resistance wire. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] In the description of this invention, it should be understood that the terms "coaxial," "bottom," "one end," "top," "middle," "other end," "upper," "side," "top," "inner," "front," "center," "both ends," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0048] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," "fixing," "screw connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0049] Example 1

[0050] Combination Figure 1-5As shown, this embodiment of the invention provides an experimental device for CO2 deposition characteristics of asphalt-containing crude oil, including a first water injection pump 1, a CO2 intermediate container 3, a core holder 4, a vertical test section, a horizontal test section, a gas-liquid separator 8, and a gas flow meter connected in sequence via a high-pressure pipeline 2. The bottom of the core holder 4 is connected to a second water injection pump 13 via the high-pressure pipeline 2. A constant temperature chamber 12 is provided around the core holder 4 to provide the constant temperature required for experimental simulation.

[0051] Both the vertical and horizontal test sections include a pressure-resistant glass tube and several annular heating blocks 6. The number of annular heating blocks 6 can be set to be the same or different according to the test requirements. In this embodiment of the invention, the vertical test section includes a vertical pressure-resistant glass tube 11 and three annular heating blocks 6 connected in series around it. The horizontal test section includes a horizontal pressure-resistant glass tube 7 and a longer annular heating block group 6 around it. Each annular heating block 6 is a partially closed ring-shaped cylindrical structure, wrapped around the pressure-resistant glass tube 8 and with reserved observation positions. Each annular heating block 6 has several parallel heating resistance wires 612 inside, which can provide a set temperature to the pressure-resistant glass tube 8 at different test positions and form a gradient temperature field through several annular heating blocks 6 connected end to end.

[0052] The annular heating block 6 also includes a stainless steel shell and a temperature sensor 611 disposed on the stainless steel shell, and the heating resistance wire 612 is evenly distributed in a ring inside the stainless steel shell.

[0053] The core holder 4 includes a rectangular cavity structure consisting of a stainless steel pressure-resistant outer shell 411 and an inner rubber sleeve 412. The core 416 is placed inside the rubber sleeve 412. The stainless steel pressure-resistant outer shell 411 has a left threaded connection hole 413, a right threaded connection hole 414, and a bottom threaded hole 415 on its left and right sides and bottom, respectively. The left threaded connection hole 413 is a carbon dioxide injection port, the right threaded connection hole 414 is an outlet for the produced well fluid, and the bottom threaded connection hole 415 is connected to a second water injection pump 13 through a high-pressure pipeline 2. The second water injection pump 13 is used to inject water into the cavity of the core holder, so that the sealed space between the outermost stainless steel pressure-resistant outer shell 411 and the inner rubber sleeve 412 of the core holder 4 is filled with water, forming a certain water pressure. The water pressure formed by the water injection simulates the formation pressure.

[0054] The bottom of the gas-liquid separator 8 is marked with graduations for measuring the volume of extracted oil and the volume of asphalt deposits. During measurement, the asphalt is a denser deposit that settles below the oil. The outlet of the gas-liquid separator 8 is connected to a gas meter 9, which is used to measure the CO2 content.

[0055] Example 2

[0056] This invention provides an experimental apparatus for the CO2 deposition characteristics of asphaltene-containing crude oil, based on Embodiment 1, as described below:

[0057] Water is filled inside the stainless steel pressure-resistant outer shell of the core holder 4 and in the gap around the heating resistance wire 612; the heating resistance wire 612 is a waterproof heating rod; this setting makes the heating more uniform and efficient, and achieves better temperature control.

[0058] Each annular heating block 6 is a three-quarter ring cylinder, with a quarter section reserved for easy observation; the heating resistance wire 612 and temperature sensor 611 of each annular heating block 6 are connected to the temperature controller 10 via signal line 14; the temperature controller 10 changes the temperature and the rate of temperature rise by changing the number of parallel heating resistance wires 612 connected to the circuit, and stops heating when the set temperature is reached, thus achieving closed-loop precise control of the temperature.

[0059] Example 3

[0060] The pressure-resistant glass pipeline 8 in the vertical test section is a vertical pressure-resistant glass pipeline 11, and the vertical pressure-resistant glass pipeline 11 is surrounded by three sets of annular heating blocks 6 connected end to end; the pressure-resistant glass pipeline 8 in the horizontal test section is a horizontal pressure-resistant glass pipeline 12, and the horizontal pressure-resistant glass pipeline 12 is surrounded by one set of annular heating blocks 6, and the diameter of the horizontal pressure-resistant glass pipeline 12 is larger than that of the vertical pressure-resistant glass pipeline 11. The purpose of this is that, in order to reduce flow resistance, the diameter of the crude oil surface transportation pipeline is designed to be larger than that of the wellbore pipeline. Therefore, setting the diameter of the horizontal pressure-resistant glass pipeline 12 to be larger than that of the vertical pressure-resistant glass pipeline 11 achieves a more realistic simulation effect.

[0061] The two ends of the pressure-resistant glass pipeline 8 are connected to the high-pressure pipeline 2 through elastic rubber sleeves 111 and adapters 112. The elastic rubber sleeves 111 are located between the end of the pressure-resistant glass pipeline 8 and the adapters 112.

[0062] Example 4

[0063] This invention provides a quantitative evaluation method for the CO2 injection deposition characteristics of asphaltene-containing crude oil, using an experimental device for CO2 injection deposition characteristics of asphaltene-containing crude oil as described above. The experimental device includes a first water injection pump 1, a CO2 intermediate container 3, a core holder 4, a vertical test section, a horizontal test section, a gas-liquid separator 8, and a gas flow meter connected in sequence. The bottom of the core holder 4 is connected to a second water injection pump 13.

[0064] The method includes:

[0065] Step S01: The first water injection pump 1 injects water into the bottom of the CO2 intermediate container 3 to form pressure. After reaching the simulated formation pressure, the CO2 in the CO2 intermediate container 3 flows into the core holder 4 through the high-pressure pipeline 2 under pressure.

[0066] Step S02: The core holder 4 contains a core 416. The second water injection pump 13 injects water into the core holder 4, so that the sealed space between the outermost stainless steel pressure-resistant shell 411 and the inner rubber sleeve 412 of the core holder 4 is filled with water, forming a certain water pressure. The water pressure formed by water injection is used to simulate the formation pressure. At the same time, by injecting CO2 and water, it can be used to simulate the process of CO2 interacting with asphalt-containing crude oil in the formation during the oil extraction process.

[0067] Step S03: The pressure-resistant glass pipeline 8 of the vertical test section is a vertical pressure-resistant glass pipeline 11, and the vertical pressure-resistant glass pipeline 11 is surrounded by three sets of annular heating blocks 6 connected end to end; the pressure-resistant glass pipeline 8 of the horizontal test section is a horizontal pressure-resistant glass pipeline 12, and the horizontal pressure-resistant glass pipeline 12 is surrounded by one set of annular heating blocks 6, and the diameter of the horizontal pressure-resistant glass pipeline 12 is larger than that of the vertical pressure-resistant glass pipeline 11. The purpose is that, in order to reduce flow resistance, the diameter of the crude oil surface transportation pipeline is designed to be larger than that of the wellbore pipeline. Therefore, the diameter of the horizontal pressure-resistant glass pipeline 12 is set to be larger than that of the vertical pressure-resistant glass pipeline 11 to achieve a more realistic simulation effect.

[0068] The annular heating block 6 has a partially closed annular cylindrical structure and contains a heating resistance wire 612 and water. Each annular heating block 6 is wrapped around a pressure-resistant glass tube 8. The water is heated by the heating resistance wire 612, thereby heating the glass tube surrounding it. The unwrapped glass tube portion is used to observe the deposition conditions inside the glass tube.

[0069] Step S04: The gas-liquid separator 8 separates the crude oil and the asphalt carried by it from the product material;

[0070] Step S05: Gas meter 9 measures the CO2 carried out by the oil;

[0071] Step S06: Store the experimental data on the precipitation points and amounts of asphaltene deposits in relation to temperature and pressure changes in the PVTSim software. Subsequently, for different reservoir types, directly call the experimental data of the corresponding reservoirs pre-stored in the PVTSim software to clarify the pattern of asphaltene precipitation points and amounts in relation to temperature and pressure changes in the corresponding reservoirs.

[0072] Specifically, in step S03, each annular heating block 6 is a three-quarter ring cylinder wrapped around a pressure-resistant glass tube 8; the annular heating block 6 also includes a stainless steel shell and a temperature sensor 611 disposed on the stainless steel shell, and the heating resistance wires 612 are evenly distributed in parallel inside the stainless steel shell; the heating resistance wires 612 and the temperature sensor 611 are respectively connected to the temperature controller 10 through signal lines 14; the temperature sensor 611 built into the annular heating block 6 can return the temperature of the annular heating block 6 to the temperature controller 10 in real time, and the temperature controller 10 can change the temperature and the rate of temperature rise by changing the number of parallel heating resistance wires 612 connected to the circuit, and stop heating when the set temperature is reached, thereby realizing closed-loop control of the temperature.

[0073] The two sets of pressure-resistant glass pipelines 8 with different diameters in the vertical test section and the horizontal test section are used to simulate the wellbore and surface pipelines during the crude oil recovery process, respectively; the vertical pressure-resistant glass pipeline 11 is used to simulate the flow of asphalt-containing crude oil in the wellbore, and the horizontal pressure-resistant glass pipeline 12 is used to simulate the flow of asphalt-containing crude oil after extraction in the surface pipeline.

[0074] The above description is merely an embodiment of this application and is not intended to limit the invention. Any modifications, equivalent substitutions, and improvements made within the scope of this application should be included within the protection scope of this invention.

Claims

1. An experimental apparatus for determining the CO2 injection deposition characteristics of a bitumastic crude oil, characterized by, It comprises a first water injection pump (1), a CO2 intermediate container (3), a core holder (4), a vertical test section, a horizontal test section, a gas-liquid separator (8) and a gas flow meter connected in sequence; The vertical test section and the horizontal test section each comprise a section of pressure-resistant glass pipeline and a plurality of annular heating blocks (6) connected in sequence, the number of the annular heating blocks (6) of the two being set as the same or different according to the need; each annular heating block (6) is an incomplete closed ring cylinder structure, wrapped around the pressure-resistant glass pipeline and leaving an observation position; A plurality of parallel heating resistance wires (612) are arranged inside each annular heating block (6) for providing a set temperature for the pressure-resistant glass pipeline (11), and a gradient temperature field is formed through the plurality of annular heating blocks (6) connected in sequence; The annular heating block (6) further comprises a stainless steel shell and a temperature sensor (611) arranged on the stainless steel shell, and the heating resistance wires (612) are annularly and uniformly arranged inside the stainless steel shell; the heating resistance wires (612) and the temperature sensor (611) are respectively connected with a temperature controller (10) through signal lines (14); Water is injected into the gap outside the heating resistance wires (612) in the stainless steel shell; the heating resistance wires (612) are waterproof heating rods; The pressure-resistant glass pipeline of the vertical test section is a vertical pressure-resistant glass pipeline (11), and the vertical pressure-resistant glass pipeline (11) is wrapped around by 3 groups of annular heating blocks (6) connected in sequence; The pressure-resistant glass pipeline of the horizontal test section is a horizontal pressure-resistant glass pipeline (7), and the horizontal pressure-resistant glass pipeline (7) is wrapped around by 1 group of annular heating blocks (6), and the diameter of the horizontal pressure-resistant glass pipeline (7) is greater than that of the vertical pressure-resistant glass pipeline (11); The bottom of the gas-liquid separator (8) is provided with a scale for measuring the volume of the produced oil and the volume of the asphaltene deposits; the outlet of the gas-liquid separator (8) is connected with a gas meter (9) for measuring the CO2 content.

2. The experimental device for determining the CO2 deposition characteristics of a bitumastic crude oil according to claim 1, characterized in that, The first water injection pump (1), the CO2 intermediate container (3), the core holder (4), the vertical test section, the horizontal test section, the gas-liquid separator (8) and the gas flow meter are connected in sequence through a high-pressure pipeline (2); a thermostat (12) is arranged around the core holder (4).

3. The experimental device for determining the CO2 deposition characteristics of a bitumastic crude oil according to claim 2, characterized in that, The two ends of the pressure-resistant glass pipeline are connected with the high-pressure pipeline (2) through an elastic rubber sleeve (111) and an adapter (112), and the elastic rubber sleeve (111) is located between the end of the pressure-resistant glass pipeline (11) and the adapter (112).

4. The experimental device for determining the CO2 deposition characteristics of a bitumastic crude oil according to claim 1, characterized in that, The core holder (4) comprises a rectangular cavity structure composed of a stainless steel pressure-resistant shell (411) and an internal rubber sleeve (412), the rubber sleeve (412) internally places a core (416); the left and right sides of the stainless steel pressure-resistant shell (411) are respectively provided with a left threaded connecting hole (413) and a right threaded connecting hole (414); the left threaded connecting hole (413) is a carbon dioxide injection port, and the right threaded connecting hole (414) is a flow outlet of produced well stream.

5. The experimental device for determining the CO2 injection deposition characteristics of a bituminous crude oil according to claim 4, characterized in that, The bottom of the stainless steel pressure-resistant shell (411) is provided with a bottom threaded connecting hole (415); the bottom threaded connecting hole (415) is communicated with the second water injection pump (13) through the high-pressure pipeline (2).

6. The experimental apparatus for determining the CO2 injection deposition characteristics of a bituminous crude oil according to claim 1, characterized in that, Each annular heating block (6) is a three-quarter ring cylinder.

7. A method for quantitatively evaluating CO2 deposition characteristics of an asphaltene-containing crude oil, using the experimental apparatus for CO2 deposition characteristics of an asphaltene-containing crude oil according to any one of claims 1 to 6, characterized by, The experimental device comprises, in sequence, a first water injection pump (1), a CO2 intermediate container (3), a core holder (4), a vertical test section, a horizontal test section, a gas-liquid separator (8) and a gas flow meter, the bottom of the core holder (4) is communicated with the second water injection pump (13); The method comprises: Step S01: the first water injection pump (1) injects water into the bottom of the CO2 intermediate container (3) to form pressure, after reaching the simulated formation pressure, the CO2 in the CO2 intermediate container (3) flows into the inside of the core holder (4) under pressure through the high-pressure pipeline (2); Step S02: the core holder (4) internally contains a core (416), the second water injection pump (13) injects water into the cavity of the core holder (4) to form water pressure for simulating formation pressure, and through the injection of CO2 and water, the process of CO2 interacting with asphalt-containing crude oil in the formation during the oil production process is simulated; Step S03: the pressure-resistant glass pipeline (11) of the vertical test section is a vertical pressure-resistant glass pipeline (11), the periphery of the vertical pressure-resistant glass pipeline (11) is wrapped with 3 groups of annular heating blocks (6) connected in sequence; the pressure-resistant glass pipeline (11) of the horizontal test section is a horizontal pressure-resistant glass pipeline (7), the periphery of the horizontal pressure-resistant glass pipeline (7) is wrapped with one group of annular heating blocks (6), and the diameter of the horizontal pressure-resistant glass pipeline (7) is greater than that of the vertical pressure-resistant glass pipeline (11); The annular heating block (6) is an incomplete closed ring cylinder structure, internally contains heating resistance wire (612) and water; each annular heating block (6) is wrapped on the pressure-resistant glass pipeline (11), the water is heated by the heating resistance wire (612) to realize the heating of the surrounded glass pipeline, and the part of the glass pipeline not wrapped is used to observe the deposition condition in the glass pipeline; Step S04: the gas-liquid separator (8) separates the crude oil and the asphalt carried out of the crude oil in the produced matter; Step S05: the gas meter (9) measures the CO2 carrying oil. Step S06: Store the experimental data of asphaltene precipitation point and precipitation amount changing with temperature and pressure in PVTSim software, and directly call the pre-stored experimental data of corresponding reservoir in PVTSim software for subsequent different reservoir types, and determine the law of asphaltene precipitation point and precipitation amount changing with temperature and pressure of corresponding reservoir.

8. The method for quantitatively evaluating the CO2 deposition characteristics of a bitumastic crude oil according to claim 7, characterized in that, Each annular heating block (6) is a three-quarter ring cylinder wrapped on a pressure-resistant glass pipeline (11); the annular heating block (6) further comprises a stainless steel shell and a temperature sensor (611) arranged on the stainless steel shell, and the heating resistance wire (612) is annularly and uniformly distributed in parallel inside the stainless steel shell; the heating resistance wire (612) and the temperature sensor (611) are respectively connected with the temperature controller (10) through signal lines (14).

9. The method for quantitatively evaluating the CO2 deposition characteristics of a bitumastic crude oil according to claim 8, characterized in that, The temperature sensor (611) built in the annular heating block (6) returns the temperature of the annular heating block (6) to the temperature controller (10) in real time, the temperature controller (10) changes the temperature and the temperature rising speed by changing the number of parallel heating resistance wires (612) connected to the circuit, and stops heating when the set temperature is reached, thereby realizing closed-loop control of the temperature.

10. The method for quantitatively evaluating the CO2 deposition characteristics of a bitumastic crude oil according to claim 7, characterized by, The two groups of pressure-resistant glass pipelines (11) with different diameters in the vertical test section and the horizontal test section are respectively used to simulate the wellbore and the ground pipeline in the crude oil recovery process; the vertical pressure-resistant glass pipeline (11) is used to simulate the flow of asphaltene-containing crude oil in the wellbore, and the horizontal pressure-resistant glass pipeline (7) is used to simulate the flow condition of the asphaltene-containing crude oil after recovery in the ground pipeline.

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