Experimental device and experimental method for displacing methane by carbon dioxide in porous medium

Abstract

The embodiment of the invention provides an experimental device and an experimental method for displacing methane by carbon dioxide in a porous medium, the device comprises a porous medium core model made of a transparent material, the core model is hollow, and two ends of the core model are respectively connected with a gas injection assembly and a gas recovery assembly; an infrared spectrometer is arranged on the outer side of the rock core model, an infrared detector is arranged on the side, away from the infrared spectrometer, in the rock core model in the displacement direction, and the infrared detector converts residual infrared light into an electric signal and outputs the electric signal to the infrared spectrometer; and the calculation module is used for receiving an electric signal sent by the infrared detector in real time, and visually displaying a displacement path, gas distribution characteristics and a displacement front flow process when methane is displaced by carbon dioxide according to the electric signal. The embodiment of the invention can accurately reflect the phase state characteristic change and the displacement characteristic when the carbon dioxide displaces the methane in the stratum, and provides powerful support for improving the recovery ratio.

Description

Technical Field

[0001] The embodiments of this specification relate to the field of gas displacement, and in particular, to an experimental device and an experimental method for displacing methane with carbon dioxide in a porous medium. Background Art

[0002] CCS / CCUS technology is the main technical choice for realizing the low-carbon and zero-carbon utilization of fossil energy, while CCUS-EOR and CCUS-EGR are the main ways to utilize carbon dioxide on a large scale, and are also important research targets in the field of oil exploration. Taking the gas reservoirs in the Sichuan Basin as an example, the gas reservoirs there are rich in types and quantity, and most of them are in the middle and late stages of development, and the potential of CCS / CCUS is huge. However, the process of carbon dioxide displacing methane during carbon dioxide injection into gas reservoirs, the characteristics of gas mixing, and the changes in the phase characteristics of carbon dioxide and methane under different temperatures and pressures are still unclear. Therefore, it is necessary to carry out phase characteristic experiments and implement the mechanism of improving the recovery rate of CCUS-EGR, which will provide strong support for stabilizing the production of old gas reservoirs, improving the recovery rate, and maximizing the comprehensive benefits of gas reservoirs.

[0003] There are few experimental methods for studying the phase characteristics of methane and carbon dioxide mixtures. Many phase characteristics experiments are conducted in experimental containers, such as detection by PVT phase state instrument, which cannot accurately reflect the phase characteristics changes and displacement characteristics when carbon dioxide displaces methane in the formation. Especially for porous medium formations, due to the particularity of the porous medium formation structure, the core is very dense and the pore structure is difficult to distinguish with the naked eye. The existing experimental equipment cannot accurately reflect the phase characteristics changes and displacement characteristics when carbon dioxide displaces methane in the formation.

[0004] Therefore, there is an urgent need for an experimental device for displacing methane with carbon dioxide in porous media, which can accurately reflect the phase characteristic changes and displacement characteristics when carbon dioxide displaces methane in the formation, and provide strong support for stabilizing production in old gas reservoirs, improving recovery rates, and maximizing the comprehensive benefits of gas reservoirs. Summary of the invention

[0005] The purpose of the embodiments of this specification is to provide an experimental device and experimental method for replacing methane with carbon dioxide in porous media, so as to accurately reflect the phase characteristic changes and displacement characteristics when carbon dioxide replaces methane in the formation, and provide strong support for stabilizing production in old gas reservoirs, improving recovery rates, and maximizing the comprehensive benefits of gas reservoirs.

[0006] To achieve the above objectives, on the one hand, the embodiments of this specification provide an experimental device for displacing methane with carbon dioxide in a porous medium, comprising:

[0007] A porous medium core model made of a transparent material, wherein the core model is hollow inside, and both ends of the core model are respectively connected with a gas injection assembly for injecting methane and carbon dioxide, and a gas recovery assembly for recovering methane and carbon dioxide;

[0008] An infrared spectrometer is arranged outside the core model, and an infrared detector is arranged in the core model on one side away from the infrared spectrometer along the displacement direction. The infrared spectrometer is used to emit infrared light. After the infrared light is partially absorbed by carbon dioxide and methane in the displacement process, the infrared detector receives the remaining infrared light, and the infrared detector converts the remaining infrared light into an electrical signal and outputs it to the infrared spectrometer;

[0009] It also includes a computing module, which is electrically connected to the infrared spectrometer and is used to receive the electrical signal sent by the infrared detector in real time, and visualize the displacement path, gas distribution characteristics and displacement front flow process when carbon dioxide displaces methane according to the electrical signal.

[0010] Preferably, a heat exchange component for controlling the displacement temperature through heat exchange is provided in the hollow cavity, and the heat exchange component is formed by a combination of a heat exchange element and a cold exchange element.

[0011] Preferably, the heat exchange element is a heating rod arranged along the displacement direction or a heat conduction pipe arranged along the displacement direction and used for passing a heat conduction medium.

[0012] Preferably, the cold exchange element is a cooling pipe which is sleeved or wound on the heat exchange element along the displacement direction, and the cooling pipe is used for passing a cooling medium.

[0013] Preferably, the gas injection assembly further comprises a methane pipeline for injecting methane gas, a carbon dioxide pipeline for injecting carbon dioxide gas, and a main injection pipeline having one end connected to both the methane pipeline and the carbon dioxide pipeline and the other end connected to the core model.

[0014] Preferably, the device further comprises:

[0015] A plurality of cameras for recording the displacement process are arranged in the hollow cavity along the displacement direction;

[0016] Sensors for detecting displacement temperature and pressure are arranged in the core model along the displacement direction;

[0017] The computing module is electrically connected to the sensor and the camera, and is used to receive the electrical signals sent by the sensor and the camera in real time, and to visualize the displacement environment, displacement path, gas distribution characteristics and displacement front flow process when carbon dioxide displaces methane according to the electrical signals.

[0018] On the other hand, an embodiment of this specification provides an experimental method for displacing methane with carbon dioxide in a porous medium, using any of the experimental devices described above, the method comprising:

[0019] S1: After performing air tightness test on the experimental device, injecting methane into the core model through a gas injection assembly;

[0020] S2: After the pressure in the core model is stabilized to a set pressure, carbon dioxide is injected into the core model through a gas injection assembly, so that the carbon dioxide displaces methane;

[0021] S3: During the displacement process, the displacement temperature is controlled to reach a set temperature, so that carbon dioxide with corresponding phase characteristics at a corresponding temperature displaces methane;

[0022] S4: The infrared spectrometer sends the displacement state information at each moment to the calculation module via an electrical signal;

[0023] S5: The calculation module visualizes the displacement path, gas distribution characteristics and displacement front flow process when carbon dioxide displaces methane based on the displacement state information.

[0024] Preferably, during the displacement process, a cold and heat exchange component is used to control the displacement temperature to reach a set temperature;

[0025] By changing the set temperature through the cold-heat exchange component, the above steps S1-S5 are repeated to obtain the displacement path, gas distribution characteristics and displacement front flow process when carbon dioxide displaces methane with different phase characteristics at different temperatures.

[0026] Preferably, when injecting carbon dioxide into the core model through the gas injection assembly, the injection is performed at a constant pressure or a constant rate;

[0027] Under the condition that the displacement temperature is the set temperature, the injection pressure or injection rate of carbon dioxide is changed to cycle the above steps S1-S5 to obtain the displacement path, gas distribution characteristics and displacement front flow process when carbon dioxide displaces methane with different phase characteristics at the same displacement temperature, different injection pressures or different injection rates.

[0028] Preferably, it also includes:

[0029] The calculation module receives the methane injection amount sent by the gas injection component and the methane recovery amount sent by the gas recovery component;

[0030] The methane recovery rate is calculated based on the methane injection amount and the methane recovery amount.

[0031] On the other hand, an embodiment of the present specification further provides a computer device, including a memory, a processor, and a computer program stored in the memory, wherein when the computer program is executed by the processor, the instructions according to any one of the methods described above are executed.

[0032] On the other hand, an embodiment of the present specification further provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor of a computer device, the computer program executes instructions according to any one of the methods described above.

[0033] It can be seen from the technical solutions provided in the above embodiments of this specification that the device of the embodiments of this specification and the method used in conjunction with the device can heat or cool the fluid in the core model, and the phase characteristic changes and displacement characteristics when carbon dioxide displaces methane in the formation can be accurately reflected through the transparent and visual core model, so as to determine the mechanism of increased recovery rate, and provide strong support for stabilizing production of old gas reservoirs, improving recovery rate, and maximizing the comprehensive benefits of gas reservoirs.

[0034] In order to make the above and other purposes, features and advantages of the present specification more obvious and easy to understand, the following specifically cites preferred embodiments and describes them in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 A partial structural schematic diagram of an experimental device for displacing methane with carbon dioxide in a porous medium provided in an embodiment of this specification is shown;

[0037] Figure 2 The overall structure schematic diagram of an experimental device for displacing methane with carbon dioxide in a porous medium provided in an embodiment of this specification is shown;

[0038] Figure 3 A schematic flow chart of an experimental method for displacing methane with carbon dioxide in a porous medium provided in an embodiment of this specification is shown;

[0039] Figure 4 A schematic diagram of the structure of a computer device provided in an embodiment of this specification is shown.

[0040] Description of the accompanying symbols:

[0041] 1. Core model; 1.1. Core internal structure; 1.2. Shell; 1.3. Cavity; 2. Infrared spectrometer; 3. Computer; 4. Injection main pipeline; 5. Methane pipeline; 6. Carbon dioxide pipeline; 7. Recovery pipeline; 8. Recovery device; 9. Injection flow meter; 10. Sensor; 11. First pressure gauge; 12. Second pressure gauge; 13. Camera; 14. Back pressure pump; 15. Vacuum pump; 16. Prepare pipeline; 1.4. Cold and heat exchange Components; 1.4.1, heat exchanger; 1.4.2, cooling pipe; 1.5, pipe wall; 2.1, infrared detector; 402, computer equipment; 404, processor; 406, memory; 408, drive mechanism; 410, input / output module; 412, input device; 414, output device; 416, presentation device; 418, graphical user interface; 420, network interface; 422, communication link; 424, communication bus. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of this specification to clearly and completely describe the technical solutions in the embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the embodiments of this specification.

[0043] There are few experimental methods for studying the changes in the phase characteristics of a mixture of methane and carbon dioxide. Many phase characteristic experiments are conducted in experimental containers, such as detection by a PVT phase state meter, which cannot accurately reflect the phase characteristic changes and displacement characteristics when carbon dioxide displaces methane in the formation. In particular, for porous medium formations, due to the particularity of the porous medium formation structure, the core is very dense and the pore structure is difficult to distinguish with the naked eye. The existing experimental device cannot accurately reflect the phase characteristic changes and displacement characteristics when carbon dioxide displaces methane in the formation. In order to solve the above problems, the embodiments of this specification provide an experimental device for displacing methane with carbon dioxide in a porous medium.

[0044] It should be noted that the terms "first", "second", etc. in the description and claims of the embodiments of this specification and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of this specification described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, device, product or equipment that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0045] Reference Figure 1 and Figure 2 The present invention provides an experimental device for displacing methane with carbon dioxide in a porous medium, comprising:

[0046] A porous medium core model 1 made of a transparent material, wherein the core model 1 is hollow inside, and both ends of the core model 1 are respectively connected with a gas injection assembly for injecting methane and carbon dioxide, and a gas recovery assembly for recovering methane and carbon dioxide;

[0047] Multiple groups of cameras 13 for recording the displacement process are arranged in the hollow cavity 1.3 along the displacement direction;

[0048] The core model 1 is provided with a sensor 10 for detecting displacement temperature and pressure along the displacement direction;

[0049] An infrared spectrometer 2 is arranged outside the core model 1, and an infrared detector 2.1 is arranged on one side of the core model 1 away from the infrared spectrometer 2 along the displacement direction. The infrared spectrometer 2 is used to emit infrared light. After the infrared light is partially absorbed by carbon dioxide and methane in the displacement process, the infrared detector 2.1 receives the remaining infrared light, and the infrared detector 2.1 converts the remaining infrared light into an electrical signal and outputs it to the infrared spectrometer 2;

[0050] The hollow cavity 1.3 is provided with a heat exchange component 1.4 for controlling the displacement temperature by heat exchange, and the heat exchange component 1.4 is formed by a combination of a heat exchange element 1.4.1 and a cold exchange element;

[0051] It also includes a computing module, which is electrically connected to the infrared spectrometer 2 and is used to receive the electrical signal sent by the infrared detector 2.1 in real time, and visualize the displacement path, gas distribution characteristics and displacement front flow process when carbon dioxide displaces methane according to the electrical signal.

[0052] The computing module is electrically connected to the sensor 10 and the camera 13, and is used to receive the electrical signals sent by the sensor 10 and the camera 13 in real time, and visualize the displacement environment, displacement path, gas distribution characteristics and displacement front flow process when carbon dioxide displaces methane according to the electrical signals.

[0053] In the embodiment of the present specification, the gas injection assembly further includes a methane pipeline 5 for injecting methane gas, a carbon dioxide pipeline 6 for injecting carbon dioxide gas, and a main injection pipeline 4 connected to both the methane pipeline 5 and the carbon dioxide pipeline 6 at one end and connected to the core model 1 at the other end. Valves are connected to both the methane pipeline 5 and the carbon dioxide pipeline 6, and a valve is also connected to the main injection pipeline 4. The main injection pipeline 4 is also provided with an injection flowmeter 9 and a first pressure gauge 11, which are used to detect the gas flow and gas pressure injected through the main injection pipeline 4, respectively.

[0054] The gas recovery component also includes a recovery pipeline 7, a back-pressure pump 14 and a recovery device 8. The recovery device 8 is provided with a recovery flow meter for detecting the recovered gas flow rate. A valve is provided on the pipeline where the back-pressure pump 14 is located.

[0055] The porous medium core model 1 is made of a transparent material of high temperature and high pressure, so that the infrared light emitted by the infrared spectrometer 2 can pass through. The core model 1 includes a core internal structure 1.1 and a shell 1.2. The shell 1.2 wraps the core internal structure 1.1 to protect it. The core of the research block is CT scanned, and a three-dimensional digital core is constructed according to the CT scanning results. Then, the core internal structure 1.1 is made by 3D printing technology or casting technology based on the three-dimensional digital core. The core internal structure 1.1 is hollow inside, and the hollow cavity 1.3 is arranged along the displacement direction, and a pipe wall 1.5 for protecting the core internal structure 1.1 is arranged on the inner wall of the cavity 1.3.

[0056] Generally speaking, the core model 1 is arranged in a rectangular parallelepiped or a cylinder, and the displacement direction is the long side direction of the rectangular parallelepiped or the axial direction of the cylinder, which is collectively referred to as the length direction in the embodiments of this specification.

[0057] During the experiment, methane is first introduced into the core model 1 through the methane pipeline 5. When the pressure in the core model 1 is stabilized to the set pressure, carbon dioxide is introduced into the core model 1 through the carbon dioxide pipeline 6. At this time, carbon dioxide will displace methane, and the entire displacement process will be detected by the sensor 10, the camera 13 and the infrared spectrometer 2. The sensor 10 can be a light sensor 10, which is arranged in the core internal structure 1.1 along the displacement direction. The camera 13 is provided with multiple groups. The camera 13 is a 360° high-definition camera 13 resistant to high temperature and high pressure. Each group of cameras 13 is provided with multiple groups. The multiple groups of cameras 13 are evenly spaced along the displacement direction. The multiple cameras 13 in each group of cameras 13 are evenly distributed along the circumference of the cavity 1.3, so as to be able to fully record the displacement process. The multiple groups of cameras 13 are distributed inside the hollow cavity 1.3, located between the pipe wall 1.5 and the cold and heat exchange component 1.4.

[0058] At each moment, the sensor 10, the camera 13 and the infrared spectrometer 2 will send the detected displacement state information to the calculation module in the form of an electrical signal. The sensor 10 is used to detect the temperature and pressure during the displacement process, and the camera 13 is used to capture images of the displacement process. However, it should be noted that since both methane and carbon dioxide are colorless gases, in order to enable the camera 13 to capture more clearly, the carbon dioxide in the experiment can be dyed, for example, by using an organic colored solvent to dye the liquid carbon dioxide, so as to more clearly distinguish between methane and carbon dioxide.

[0059] The infrared detector 2.1 is used in conjunction with the infrared spectrometer 2. The infrared detector 2.1 is arranged in the core internal structure 1.1 along the displacement direction and is located on the side away from the infrared spectrometer 2. After the infrared spectrometer 2 emits infrared light, the infrared light penetrates the core model 1. The methane or carbon dioxide in the core pores will absorb a part of it, and the remaining part of the infrared light is received by the infrared detector 2.1 and sent to the infrared spectrometer 2. Since different gases have different characteristics of absorbing infrared rays, the infrared spectrometer 2 can detect the gas distribution when carbon dioxide displaces methane in real time.

[0060] In this way, the calculation module can obtain the displacement environment based on the temperature and pressure analysis during the displacement process, and obtain the displacement path, gas distribution characteristics and displacement front flow process based on the image and gas distribution of the displacement process, and visualize them in the form of images and videos.

[0061] It should be noted that after the components in the experimental device are connected and assembled, an air-tightness check is required before the formal experiment is carried out. After the air-tightness check, a preparation component is also provided in the device, and the preparation component includes a preparation pipeline 16 and a vacuum pump 15, and a valve located on the preparation pipeline 16. The air-tightness check component and the gas recovery component are located on the same side, that is, the production end of the device. The preparation pipeline 16 and the recovery pipeline 7 are connected to a production main pipeline. The end of the production main pipeline away from the preparation pipeline 16 and the recovery pipeline 7 is connected to the core model 1. A second pressure gauge 12 is provided on the production main pipeline for detecting the pressure of the gas flowing through.

[0062] After the air tightness check, open the valve on the preparation pipeline 16 and the vacuum pump 15. After vacuuming for 20 to 24 hours, close the valve on the preparation pipeline 16 and the vacuum pump 15 to prepare for the injection of methane and carbon dioxide gases.

[0063] In addition, in order to better study the displacement path, gas distribution characteristics and displacement front flow process when carbon dioxide with different phase characteristics displaces methane, the displacement temperature can be changed through the heat exchange component 1.4 to obtain carbon dioxide with different phase characteristics, and multiple comparative experiments can be carried out.

[0064] The heat exchange assembly 1.4 is formed by a combination of a heat exchange element 1.4.1 and a cold exchange element. The heat exchange element 1.4.1 is a heating rod arranged along the displacement direction or a heat pipe arranged along the displacement direction for passing a heat transfer medium. The temperature can be heated from room temperature, generally 25°C, to hundreds of degrees Celsius. Due to the special properties of carbon dioxide, it has different phase changes at different temperatures. When the temperature is higher than 32 degrees Celsius, it can form a supercritical state. When the temperature is lower than 32°C, it can become a gas or liquid under different pressures. Therefore, in order to study the effect and mechanism of carbon dioxide displacing methane with different phase characteristics, it is necessary to control a wide temperature range, and it is also necessary to study the phase characteristics of carbon dioxide under low temperature conditions. Therefore, there is a cold exchange element outside the heat exchange element 1.4.1. The cold exchange component is a cooling tube 1.4.2 which is sleeved or wound on the heat exchange component 1.4.1 along the displacement direction. The cooling tube 1.4.2 is used to pass cooling media such as liquid nitrogen, wherein the cooling tube 1.4.2 can be coaxially sleeved on the outside of the heating rod or the heat-conducting tube, and the cooling medium and the heat-conducting medium are passed in from opposite directions. The temperature can be easily controlled by passing in opposite directions to prevent misoperation during the temperature adjustment process. For example, when the cooling medium is passed in from the A end, the heat-conducting medium is passed in from the opposite B end, and vice versa. The cooling tube 1.4.2 can also be spirally wound on the outside of the heating rod or the heat-conducting tube. Whether it is sleeved or wound, the purpose is to make the cooling tube 1.4.2 fully contact with the heating rod or the heat-conducting tube to achieve the purpose of quickly adjusting the temperature.

[0065] In this way, the displacement temperature can be changed by the cold-heat exchange component 1.4, and the displacement path, gas distribution characteristics and displacement front flow process when carbon dioxide displaces methane with different phase characteristics at different temperatures can be obtained.

[0066] Generally speaking, carbon dioxide is injected at a constant pressure or constant rate. At a certain displacement temperature, the injection pressure or injection rate of carbon dioxide can be changed by adjusting the valve to conduct multiple experiments to obtain the displacement path, gas distribution characteristics and displacement front flow process when carbon dioxide displaces methane with different phase characteristics at the same displacement temperature, different injection pressures or different injection rates.

[0067] In addition to the displacement environment, displacement path, gas distribution characteristics and displacement front flow process when carbon dioxide displaces methane, the calculation module can also be electrically connected to the injection flowmeter 9 in the gas injection component and the recovery flowmeter in the gas recovery component, receive the electrical signals sent by the two flowmeters, obtain the methane injection amount and the methane recovery amount, and obtain the methane recovery rate by dividing the recovery amount by the injection amount.

[0068] Since the corresponding methane recovery rate can be obtained in each experiment, the methane recovery rate and the displacement environment, displacement path, gas distribution characteristics and displacement front flow process when carbon dioxide displaces methane during the displacement process can be jointly analyzed to obtain the displacement environment, displacement path, gas distribution characteristics and displacement front flow process when carbon dioxide displaces methane when the methane recovery rate is the highest, so as to provide strong support for stabilizing the production of old gas reservoirs, improving the recovery rate and maximizing the comprehensive benefits of gas reservoirs.

[0069] Based on the experimental device for displacing methane with carbon dioxide in a porous medium described in the embodiment of this specification, the embodiment of this specification also provides an experimental method for displacing methane with carbon dioxide in a porous medium, referring to Figure 3 , the method comprising:

[0070] S1: After performing air tightness test on the experimental device, injecting methane into the core model 1 through a gas injection assembly;

[0071] S2: After the pressure in the core model 1 is stabilized to a set pressure, carbon dioxide is injected into the core model 1 through a gas injection assembly so that the carbon dioxide displaces methane;

[0072] S3: During the displacement process, the displacement temperature is controlled to reach a set temperature, so that carbon dioxide with corresponding phase characteristics at a corresponding temperature displaces methane;

[0073] S4: The infrared spectrometer 2 sends the displacement state information at each moment to the calculation module via an electrical signal;

[0074] S5: The calculation module visualizes the displacement path, gas distribution characteristics and displacement front flow process when carbon dioxide displaces methane based on the displacement state information.

[0075] In the displacement process, the cold and heat exchange component 1.4 is used to control the displacement temperature to reach the set temperature;

[0076] By changing the set temperature through the cold-heat exchange component 1.4, the above steps S1-S5 are repeated to obtain the displacement path, gas distribution characteristics and displacement front flow process when carbon dioxide displaces methane with different phase characteristics at different temperatures.

[0077] Wherein, when injecting carbon dioxide into the core model 1 through the gas injection assembly, the injection is performed at a constant pressure or a constant speed;

[0078] Under the condition that the displacement temperature is the set temperature, the injection pressure or injection rate of carbon dioxide is changed to cycle the above steps S1-S5 to obtain the displacement path, gas distribution characteristics and displacement front flow process when carbon dioxide displaces methane with different phase characteristics at the same displacement temperature, different injection pressures or different injection rates.

[0079] The method further comprises:

[0080] The calculation module receives the methane injection amount sent by the gas injection component and the methane recovery amount sent by the gas recovery component;

[0081] The methane recovery rate is calculated based on the methane injection amount and the methane recovery amount.

[0082] In one embodiment, the experiment can be performed as follows:

[0083] a. Prepare a core model 1 according to the core characteristics of the porous medium in the block to be studied, then connect and assemble the components according to the aforementioned experimental device, and check the air tightness of the entire experimental device;

[0084] b. Connect the vacuum pump 15 to the extraction end of the core model 1, evacuate for 20 to 24 hours, close the valve on the vacuum pump 15 preparation pipeline 16, and prepare for the injection of methane and carbon dioxide gases;

[0085] c. Open the valve on the pipeline where the back pressure pump 14 is located, start the back pressure pump 14, and control the fluid production pressure;

[0086] d. First, a certain amount of natural gas is injected into the core model 1 through the methane pipeline 5. After the pressure is stabilized to the set pressure, carbon dioxide is injected into the core model 1 through the carbon dioxide pipeline 6. During the gas injection process, the injection flow meter 9 cooperates with the valve on the injection main pipeline 4 to control the injection speed, and the temperature of the core model 1 is controlled by the cold and heat exchange component 1.4;

[0087] e. During the experiment, the camera 13 acquires and records the displacement process in real time and uploads it to the calculation module, the sensor 1010 detects the displacement temperature and pressure in real time and uploads it to the calculation module, and the infrared spectrometer 2 arranged outside the core model 1 acquires the distribution characteristics of different gases in real time and transmits it to the computer 3 module;

[0088] f. The calculation module performs a real-time visualization of the displacement process based on the received data.

[0089] Through the device of the embodiment of this specification and the method used in conjunction with the device, the fluid in the core model can be heated or cooled, and the phase characteristic changes and displacement characteristics when carbon dioxide displaces methane in the formation can be accurately reflected through the transparent and visual core model, so as to determine the mechanism of increased recovery rate, and provide strong support for stabilizing production in old gas reservoirs, improving recovery rate, and maximizing the comprehensive benefits of gas reservoirs.

[0090] Reference Figure 4As shown, based on the experimental method for replacing methane with carbon dioxide in a porous medium described above, a computer device 402 is also provided in an embodiment of this specification, wherein the above method is run on the computer device 402. The computer device 402 may include one or more processors 404, such as one or more central processing units (CPUs) or graphics processing units (GPUs), and each processing unit may implement one or more hardware threads. The computer device 402 may also include any memory 406, which is used to store any kind of information such as code, settings, data, etc. In a specific embodiment, a computer program on the memory 406 and running on the processor 404, when the computer program is run by the processor 404, can execute instructions according to the above method. Non-limitingly, for example, the memory 406 may include any one or more combinations of the following: any type of RAM, any type of ROM, flash memory device, hard disk, optical disk, etc. More generally, any memory can use any technology to store information. Further, any memory can provide volatile or non-volatile retention of information. Further, any memory can represent a fixed or removable component of the computer device 402. In one embodiment, when the processor 404 executes the associated instructions stored in any memory or combination of memories, the computer device 402 can perform any operation of the associated instructions. The computer device 402 also includes one or more drive mechanisms 408 for interacting with any memory, such as a hard disk drive mechanism, an optical disk drive mechanism, etc.

[0091] The computer device 402 may also include an input / output module 410 (I / O) for receiving various inputs (via input device 412) and for providing various outputs (via output device 414). A specific output mechanism may include a presentation device 416 and an associated graphical user interface 418 (GUI). In other embodiments, the input / output module 410 (I / O), input device 412, and output device 414 may not be included, and the computer device 402 may be used as a computer device in a network. The computer device 402 may also include one or more network interfaces 420 for exchanging data with other devices via one or more communication links 422. One or more communication buses 424 couple the components described above together.

[0092] The communication link 422 may be implemented in any manner, for example, through a local area network, a wide area network (e.g., the Internet), a point-to-point connection, etc., or any combination thereof. The communication link 422 may include any combination of hardwired links, wireless links, routers, gateway functions, name servers, etc., governed by any protocol or combination of protocols.

[0093] Corresponds to Figure 3The method in the embodiment of the present specification also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the above method are executed.

[0094] The embodiment of the present specification also provides a computer-readable instruction, wherein when the processor executes the instruction, the program therein causes the processor to execute the following Figure 3 The method shown.

[0095] It should be understood that in the various embodiments of this specification, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this specification.

[0096] It should also be understood that in the embodiments of this specification, the term "and / or" is only a description of the association relationship of the associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the embodiments of this specification generally indicates that the associated objects before and after are in an "or" relationship.

[0097] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed in the embodiments of this specification can be implemented with electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the embodiments of this specification.

[0098] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0099] In the several embodiments provided in this specification, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, or it can be an electrical, mechanical or other form of connection.

[0100] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiments of this specification.

[0101] In addition, each functional unit in each embodiment of this specification may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0102] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiment of this specification is essentially or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of this specification. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program code.

[0103] Specific embodiments are used in this specification to illustrate the principles and implementation methods of the embodiments of this specification. The description of the above embodiments is only used to help understand the methods and core ideas of the embodiments of this specification. At the same time, for those skilled in the art, according to the ideas of the embodiments of this specification, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the embodiments of this specification.

Claims

1. An experimental device for displacing methane with carbon dioxide in porous media. It is characterized in that include: A porous medium core model made of a transparent material, wherein the core model is hollow inside, and both ends of the core model are respectively connected with a gas injection assembly for injecting methane and carbon dioxide, and a gas recovery assembly for recovering methane and carbon dioxide; An infrared spectrometer is arranged outside the core model, and an infrared detector is arranged in the core model on one side away from the infrared spectrometer along the displacement direction. The infrared spectrometer is used to emit infrared light. After the infrared light is partially absorbed by carbon dioxide and methane in the displacement process, the infrared detector receives the remaining infrared light, and the infrared detector converts the remaining infrared light into an electrical signal and outputs it to the infrared spectrometer; It also includes a computing module, which is electrically connected to the infrared spectrometer and is used to receive the electrical signal sent by the infrared detector in real time, and visualize the displacement path, gas distribution characteristics and displacement front flow process when carbon dioxide displaces methane according to the electrical signal.

2. The device according to claim 1, It is characterized in that A heat exchange component for controlling the displacement temperature through heat exchange is arranged in the hollow cavity, and the heat exchange component is formed by combining a heat exchange component and a cold exchange component.

3. The device according to claim 2, It is characterized in that The heat exchange element is a heating rod arranged along the displacement direction or a heat conduction pipe arranged along the displacement direction and used for passing a heat conduction medium.

4. The device according to claim 2, It is characterized in that The cold exchange element is a cooling pipe which is sleeved or wound on the heat exchange element along the displacement direction, and the cooling pipe is used for passing a cooling medium.

5. The device according to claim 1, It is characterized in that The gas injection assembly also includes a methane pipeline for injecting methane gas, a carbon dioxide pipeline for injecting carbon dioxide gas, and an injection main pipeline having one end connected to both the methane pipeline and the carbon dioxide pipeline and the other end connected to the core model.

6. The device according to claim 1, It is characterized in that The device also includes: A plurality of cameras for recording the displacement process are arranged in the hollow cavity along the displacement direction; Sensors for detecting displacement temperature and pressure are arranged in the core model along the displacement direction; The computing module is electrically connected to the sensor and the camera, and is used to receive the electrical signals sent by the sensor and the camera in real time, and to visualize the displacement environment, displacement path, gas distribution characteristics and displacement front flow process when carbon dioxide displaces methane according to the electrical signals.

7. An experimental method for displacing methane with carbon dioxide in porous media. It is characterized in that Utilizing the experimental device described in any one of claims 1 to 6, the method comprises: S1: After performing air tightness test on the experimental device, injecting methane into the core model through a gas injection assembly; S2: After the pressure in the core model is stabilized to a set pressure, carbon dioxide is injected into the core model through a gas injection assembly, so that the carbon dioxide displaces methane; S3: During the displacement process, the displacement temperature is controlled to reach a set temperature, so that carbon dioxide with corresponding phase characteristics at a corresponding temperature displaces methane; S4: The infrared spectrometer sends the displacement state information at each moment to the calculation module via an electrical signal; S5: The calculation module visualizes the displacement path, gas distribution characteristics and displacement front flow process when carbon dioxide displaces methane based on the displacement state information.

8. The method according to claim 7, It is characterized in that During the displacement process, the heat exchange component is used to control the displacement temperature to reach the set temperature; By changing the set temperature through the cold-heat exchange component, the above steps S1-S5 are repeated to obtain the displacement path, gas distribution characteristics and displacement front flow process when carbon dioxide displaces methane with different phase characteristics at different temperatures.

9. The method according to claim 7, It is characterized in that When injecting carbon dioxide into the core model through the gas injection assembly, the injection is performed at a constant pressure or a constant speed; Under the condition that the displacement temperature is the set temperature, the injection pressure or injection rate of carbon dioxide is changed to cycle the above steps S1-S5 to obtain the displacement path, gas distribution characteristics and displacement front flow process when carbon dioxide displaces methane with different phase characteristics at the same displacement temperature, different injection pressures or different injection rates.

10. The method according to claim 7, It is characterized in that Also includes: The calculation module receives the methane injection amount sent by the gas injection component and the methane recovery amount sent by the gas recovery component; The methane recovery rate is calculated based on the methane injection amount and the methane recovery amount.

11. A computer device comprising a memory, a processor, and a computer program stored on the memory, It is characterized in that When the computer program is executed by the processor, the computer program executes the instructions of the method according to any one of claims 7 to 10.

12. A computer-readable storage medium having a computer program stored thereon, It is characterized in that When the computer program is executed by a processor of a computer device, the computer program executes the instructions of the method according to any one of claims 7 to 10.

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