Experimental device and method for measuring carbon dioxide-water-rock reaction and rock core permeability by pulse method

Abstract

The invention discloses an experimental device and method for measuring carbon dioxide-water-rock reaction and rock core permeability through a pulse method, and belongs to the technical field of carbon dioxide flooding of oil and gas reservoirs. The experimental device comprises: a rock core holder for accommodating a rock core sample; the temperature heating unit is used for heating the rock core holder; the carbon dioxide pressurizing unit is used for pressurizing carbon dioxide in the rock core holder; the confining pressure adjusting unit is used for adjusting the confining pressure in the rock core holder; the pressure detection unit is used for detecting pressure; and the control unit is used for collecting and processing data provided by the pressure detection unit and controlling the temperature heating unit. The device has the beneficial effects that the experimental temperature and pressure can be more accurately and conveniently controlled; in the experimental method for carrying out the three-phase reaction by using the holder, carbon dioxide is driven in from the two ends of the rock core, so that the carbon dioxide-water-rock three-phase reaction mainly occurs in pores in the rock core, and the actual condition of reservoir carbon dioxide driving is better met.

Description

Technical Field

[0001] This invention relates to an experimental apparatus and method for measuring carbon dioxide-water-rock reaction and core permeability using a pulse method, belonging to the field of carbon dioxide flooding technology for oil and gas reservoirs. Background Technology

[0002] Carbon dioxide injection can be an effective means to improve the recovery rate of low-permeability oil and gas reservoirs. On the one hand, after carbon dioxide is injected into the reservoir, the interaction between carbon dioxide, water, and rock causes changes in the concentration of various ions and pH of formation water, generating carbonate precipitates. During the displacement process, the precipitates adsorb onto the pore throat surface, causing pore throat blockage and resulting in a decrease in porosity and permeability. On the other hand, under certain conditions, the acidic environment generated by the reaction of carbon dioxide and water can also lead to the dissolution of the core, increasing the pore volume of the core and thus improving the seepage environment for oil and gas. Under reservoir conditions, the interaction between carbon dioxide, water, and rock is very complex. Therefore, understanding and studying the three-phase interaction mechanism of carbon dioxide, water, and rock, as well as the impact of reaction products on core porosity and permeability, is of great significance for the development of low-permeability oil and gas reservoirs.

[0003] Currently, most experiments that clearly define the three-phase reaction mechanism of carbon dioxide-water-rock utilize high-temperature and high-pressure reactors and displacement devices.

[0004] The reactor experiment involves placing prepared formation water and rock cores into a high-temperature, high-pressure reactor, then pumping carbon dioxide in until the set pressure is reached. The gas injection is then stopped, and the experimental temperature is set. As the temperature rises, the carbon dioxide expands due to heat, causing the pressure to exceed the set pressure. A pressure release operation is then necessary to ensure the reactor reaches the required experimental pressure. Using a high-temperature, high-pressure reactor for three-phase static experiments requires that the experimental pressure cannot be directly controlled; it must be controlled through gas injection and venting. This process is complex, and the temperature rises slowly and fluctuates significantly, increasing the difficulty and risk of the experiment. Furthermore, during the process of placing water and rock cores into the reactor and then pumping in carbon dioxide, the rock cores are immersed in water, making it impossible to guarantee that carbon dioxide will penetrate the rock cores. The reaction primarily occurs on the rock core walls, with less reaction occurring in the internal pores, which does not reflect the actual conditions of reservoir carbon dioxide flooding.

[0005] The experimental method using a displacement device involves placing a core sample in a holder, setting confining and pore pressures, and injecting carbon dioxide and formation water at the inlet. This simulates the process of carbon dioxide injection into the reservoir and its reaction with water and rock. The entire experiment is typically conducted in a constant-temperature chamber or by using a heating device to heat the core holder, thus simulating the actual temperature of the reservoir. This experimental method can largely compensate for the shortcomings of a reaction vessel, allowing carbon dioxide to fully enter the core and react, more closely resembling the actual situation during carbon dioxide flooding in the reservoir. However, whether using a reaction vessel or a displacement device for the carbon dioxide-water-core three-phase reaction experiment, it is usually only possible to obtain the core permeability before and after the reaction, thus analyzing the impact of the three-phase reaction on the core permeability. However, the core permeability at various time points during the experiment cannot be obtained, making it difficult to analyze the mechanism of core permeability changes during the reaction. Summary of the Invention

[0006] Considering the problems of pressure control difficulties and inability to simulate real reservoir conditions in existing high-temperature and high-pressure reactor experiments, and the technical challenge of obtaining core permeability changes during the experiment using current methods, this paper designs an experimental device and method for monitoring core permeability at any time using the pulse method, based on the carbon dioxide-water-rock reaction and core permeability pulse method. This avoids the shortcomings of high-temperature and high-pressure reactor experiments and solves the problem of not being able to test core permeability during the experiment. Compared with ordinary permeability testing methods, the pulse method can test cores with extremely low permeability, and the testing speed is fast and the accuracy is high, improving the overall applicability, convenience and accuracy of the experimental method.

[0007] The technical solution of this invention is: an experimental apparatus for measuring carbon dioxide-water-rock reaction and core permeability using a pulse method, comprising:

[0008] Core holder, used to hold core samples;

[0009] Temperature heating unit, used to heat the core holder;

[0010] A carbon dioxide pressurization unit is used to pressurize carbon dioxide within the core holder.

[0011] The confining pressure adjustment unit is used to adjust the confining pressure inside the core holder;

[0012] Pressure detection unit, used for pressure detection;

[0013] The control unit is used to collect and process data provided by the pressure detection unit, as well as to control the temperature heating unit.

[0014] The confining pressure regulating unit includes a confining pressure tracking pump connected to the core holder via a confining pressure pipeline, and a control valve a is provided on the confining pressure pipeline.

[0015] The pressure detection unit includes a pressure sensor a for detecting the pressure of the confining pressure pipeline, and the pressure sensor a is connected to the control unit.

[0016] The carbon dioxide pressurization unit includes a carbon dioxide cylinder and a high-pressure storage tank connected by a gas pressurization pump. The gas pressurization pump is equipped with control valves b and c at both ends. The high-pressure storage tank outlet is equipped with a pressure regulating valve located on the main pressurization pipe. The main pressurization pipe is also equipped with a control valve d. The main pressurization pipe is connected to an upstream pressurization branch pipe and a downstream pressurization branch pipe. The upstream pressurization branch pipe and the downstream pressurization branch pipe are respectively equipped with control valves e and f. The upstream pressurization branch pipe is connected to the upstream chamber through an upstream pipeline, and the downstream pressurization branch pipe is connected to the downstream chamber through a downstream pipeline. The other ends of the upstream and downstream pipelines are connected to the upstream and downstream connection ports of the core holder, respectively.

[0017] The upstream pipeline is equipped with a control valve g at the connection end with the core holder, and the downstream pipeline is equipped with a control valve h at the connection end with the core holder.

[0018] The pressure detection unit includes a pressure sensor b for detecting the pressure of the upstream chamber, a pressure sensor c for detecting the pressure of the upstream pipeline, a pressure sensor d for detecting the pressure of the downstream pipeline, and a pressure sensor e for detecting the pressure of the downstream chamber. All of the pressure sensors b, c, d, and e are connected to the control unit.

[0019] The control unit is a PLC control system.

[0020] The temperature heating unit is an electric heating sleeve fitted onto the core holder.

[0021] This invention also claims protection for an experimental method for measuring carbon dioxide-water-rock reaction and core permeability using a pulse method, comprising the following steps:

[0022] Step 1: Core sample pretreatment;

[0023] Step 2: Adjust the pressure and temperature inside the core holder to simulate the three-phase reaction environment of carbon dioxide-water-rock in the underground reservoir;

[0024] Step 3: Test and calculate core permeability.

[0025] Step one specifically includes the following:

[0026] Step 1a: Core the reservoir rock and dry the core.

[0027] Step 1b: Measure the core porosity and permeability;

[0028] Step 1c: Prepare formation water;

[0029] Step 1d: Place the core sample into a vacuum container, pour in formation water, and evacuate to saturate the formation water for 48 hours.

[0030] Step 1e: Establish the initial water saturation of the core.

[0031] Step two specifically includes the following:

[0032] Step 2a: Connect the experimental equipment, place the rock core into the holder, ensure that all connecting pipelines are well sealed, and close all control valves;

[0033] Step 2b: Open control valve a, start the confining pressure tracking pump, set the pressure difference to 3-5MPa, and apply confining pressure;

[0034] Step 2c: The PLC control system sets the required temperature for the experiment, and the electric heating mantle begins to heat up;

[0035] Step 2d: Open control valves b and c, start the gas booster pump, and store the pressurized carbon dioxide in the high-pressure storage tank. After pressurization is complete, close control valves b and c.

[0036] Step 2 e: Open control valves d, e, and f, and inject carbon dioxide at the same pressure into the upstream and downstream chambers through the pressure regulating valve;

[0037] Step 2f: Once the core holder temperature rises to the required experimental temperature, open control valves g and h, and simultaneously inject carbon dioxide at the same pressure into both ends of the core. Once the pressure at both ends of the core holder reaches the required pore pressure and stabilizes, close control valves d, e, f, g, and h to allow a three-phase reaction to occur inside the core holder.

[0038] Step three specifically includes the following:

[0039] Step 3a: Open control valves d and e, and use the pressure regulating valve to pressurize the upstream chamber separately to create a pressure difference Δp between the upstream and downstream chambers. After pressurization is complete, close control valves d11 and e12.

[0040] Step 3b: Open control valve g and control valve h. Due to the pressure difference, carbon dioxide in the upstream chamber 14 gradually flows into the downstream chamber, and Δp decreases accordingly.

[0041] Step 3c: Use a data acquisition device to obtain the pressure change process at both ends of the clamp, and use the pulse permeability calculation formula to calculate the permeability of the rock core at this time. Calculation formula:

[0042]

[0043] In the formula, C gρ is the pore fluid compressibility coefficient of the rock core, in 1 / Pa; μ is the fluid viscosity, in Pa·s; L is the length of the rock core, in meters; V is the volume of the upstream and downstream chambers, in cubic meters per second. 3 Δp represents the initial pressure difference between the upstream and downstream chambers, in MPa; p1(t) and p2(t) are the pressure functions of the upstream and downstream chambers over time, respectively, in MPa; A is the cross-sectional area of ​​the core, in m³. 2 Δt is the test duration, in seconds.

[0044] Step 3d: After the permeability test is completed, open control valves d, e, and f, and use the gas booster pump to stabilize the pressure at both ends of the core holder and in the upstream and downstream chambers to the required pore pressure for the experiment. Then close control valves d, e, f, g, and h to continue the three-phase reaction.

[0045] Step 3e: Repeat steps 3a-3d to test core permeability;

[0046] Step 3f: After the reaction is complete, remove the rock core, dry it, and measure the core porosity and permeability.

[0047] The beneficial effects of this invention are as follows: it can control the experimental temperature and pressure more accurately and conveniently; in the experimental method of three-phase reaction using a clamp, carbon dioxide is driven in from both ends of the core, so that the three-phase reaction of carbon dioxide-water-rock mainly occurs in the pores inside the core, which is more in line with the actual situation of carbon dioxide flooding in reservoirs.

[0048] Compared to conventional experimental methods that use a clamp to conduct three-phase reactions of carbon dioxide, water, and rock, this experimental method adds an intermediate container (upstream chamber and downstream chamber) at each end of the clamp. During the experiment, a pressure difference between the two intermediate containers is created, causing carbon dioxide to flow from the inlet intermediate container through the rock core to the outlet intermediate container. By simulating the pulse method, the pressure change data at both ends of the clamp are recorded, and the rock core permeability is obtained, which serves to monitor the changes in rock core permeability at any time during the experiment. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the experimental apparatus of the present invention.

[0050] The attached figures are labeled as follows: 1. Core holder, 2. Confining pressure tracking pump, 3. Control valve a, 4. Pressure sensor a, 5. Gas booster pump, 6. Carbon dioxide cylinder, 7. High-pressure storage tank, 8. Control valve b, 9. Control valve c, 10. Pressure regulating valve, 11. Control valve d, 12. Control valve e, 13. Control valve f, 14. Upstream chamber, 15. Downstream chamber, 16. Control valve g, 17. Control valve h, 18. Pressure sensor b, 19. Pressure sensor c, 20. Pressure sensor d, 21. Pressure sensor e, 22. Electric heating jacket, 23. PLC control system. Detailed Implementation

[0051] To more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0052] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0053] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0054] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0055] The following is in conjunction with the appendix Figure 1 The present invention will be described in further detail as follows:

[0056] Example 1

[0057] An experimental apparatus for measuring carbon dioxide-water-rock reaction and core permeability using the pulse method includes: a core holder 1 for holding a core sample; a temperature heating unit for heating the core holder 1; a carbon dioxide pressurization unit for pressurizing the core holder 1; a confining pressure regulating unit for regulating the confining pressure within the core holder 1; a pressure detection unit for pressure detection; and a control unit for acquiring and processing data provided by the pressure detection unit and controlling the temperature heating unit. The confining pressure regulating unit includes a confining pressure tracking pump 2 connected to the core holder 1 via a confining pressure pipeline, and a control valve a3 is provided on the confining pressure pipeline. The pressure detection unit includes a pressure sensor a4 for detecting the pressure in the confining pressure pipeline, and the pressure sensor a4 is connected to the control unit. The carbon dioxide pressurization unit includes a carbon dioxide cylinder 6 and a high-pressure storage tank 7 connected by a gas pressurization pump 5. Control valves b8 and c9 are located at both ends of the gas pressurization pump 5. A pressure regulating valve 10 is located at the outlet of the high-pressure storage tank 7, situated on the main pressurization pipe. A control valve d11 is also located on the main pressurization pipe. The main pressurization pipe is connected to an upstream pressurization branch pipe and a downstream pressurization branch pipe. Control valves e12 and f13 are respectively located on the upstream and downstream pressurization branch pipes. The upstream pressurization branch pipe is connected to an upstream chamber 14 via an upstream pipeline, and the downstream pressurization branch pipe is connected to a downstream chamber 15 via a downstream pipeline. The other ends of the upstream and downstream pipelines are connected to the upstream and downstream connection ports of the core holder 1, respectively. A control valve g16 is located at the connection end of the upstream pipeline to the core holder 1, and a control valve h17 is located at the connection end of the downstream pipeline to the core holder 1. The pressure detection unit includes a pressure sensor b18 for detecting the pressure in the upstream chamber 14, a pressure sensor c19 for detecting the pressure in the upstream pipeline, a pressure sensor d20 for detecting the pressure in the downstream pipeline, and a pressure sensor e21 for detecting the pressure in the downstream chamber 15. All pressure sensors b18, c19, d20, and e21 are connected to a control unit. The control unit is a PLC control system 23. The temperature heating unit is an electric heating sleeve 22 fitted onto the core holder 1. In this experimental setup, ceramic plugs are used at both ends of the core holder 1, and all sealing rings and rubber sleeves are made of corrosion-resistant materials. This ensures that the experiment will not be affected by carbon dioxide corrosion during long-term reactions, greatly increasing the stability and reliability of the experiment.

[0058] This experimental setup allows carbon dioxide, water, and rock to fully contact and react under static conditions. The temperature and pressure can be conveniently and precisely controlled via a heating mantle, a booster pump, and a pressure regulating valve 10, simulating the real situation of carbon dioxide flooding in reservoirs. This overcomes the shortcomings of using a reactor for carbon dioxide-water-rock three-phase reaction experiments, where temperature and pressure are difficult to control and contact between the rock core and carbon dioxide is insufficient. The clamps are connected to two intermediate containers (upstream chamber 14 and downstream chamber 15). By creating a pressure difference between the two intermediate containers, carbon dioxide flows from the inlet intermediate container through the rock core to the outlet intermediate container, simulating a pulse method. By recording the pressure changes at both ends of the clamps, the rock core permeability can be calculated, allowing for real-time monitoring of rock core permeability changes during the experiment.

[0059] Example 2

[0060] The experimental method for measuring carbon dioxide-water-rock reaction and core permeability using the pulse method includes the following steps:

[0061] Step 1: Core sample pretreatment; specifically including the following:

[0062] Step 1a: Core the reservoir rock and dry the core.

[0063] Step 1b: Measure the core porosity and permeability;

[0064] Step 1c: Prepare formation water;

[0065] Step 1d: Place the core sample into a vacuum container, pour in formation water, and evacuate to saturate the formation water for 48 hours.

[0066] Step 1e: Establish the initial water saturation of the core.

[0067] Step Two: Adjusting the pressure and temperature within the core holder to simulate the three-phase reaction environment of carbon dioxide, water, and rock in underground reservoirs; specifically including the following:

[0068] Step 2a: Connect the experimental equipment, place the rock core into the holder, ensure that all connecting pipelines are well sealed, and close all control valves;

[0069] Step 2b: Open control valve a3, start confining pressure tracking pump 2, set the pressure difference to 3-5MPa, and apply confining pressure;

[0070] Step 2c: The PLC control system 23 sets the required temperature for the experiment, and the electric heating jacket 22 starts heating;

[0071] Step 2d: Open control valves b8 and c9, start gas booster pump 5, and store the pressurized carbon dioxide in high-pressure storage tank 7. After pressurization is complete, close control valves b8 and c9.

[0072] Step 2e: Open control valves d11, e12, and f13, and inject carbon dioxide at the same pressure into the upstream chamber 14 and the downstream chamber 15 through pressure regulating valve 10;

[0073] Step 2f: Once the temperature of the core holder 1 rises to the required experimental temperature, open control valves g16 and h17 to simultaneously inject carbon dioxide at equal pressure into both ends of the core. Once the pressure at both ends of the core holder 1 reaches the required pore pressure and stabilizes, close control valves d11, e12, f13, g16, and h17 to allow a three-phase reaction to occur within the core holder 1.

[0074] Step 3: Test and calculate core permeability; specifically including the following:

[0075] Step 3a: Open control valve d11 and control valve e12, and use the pressure regulating valve to pressurize the upstream chamber separately to create a pressure difference Δp between the upstream and downstream chambers. After pressurization is complete, close control valve d11 and control valve e12.

[0076] Step 3b: Open control valve g16 and control valve h17. Due to the pressure difference, carbon dioxide in the upstream chamber 14 gradually flows into the downstream chamber 15, and Δp decreases accordingly.

[0077] Step 3c: Use a data acquisition device to obtain the pressure change process at both ends of the clamp, and use the pulse permeability calculation formula to calculate the permeability of the rock core at this time. Calculation formula:

[0078]

[0079] In the formula, C g ρ is the pore fluid compressibility coefficient of the rock core, in 1 / Pa; μ is the fluid viscosity, in Pa·s; L is the length of the rock core, in meters; V is the volume of the upstream and downstream chambers, in cubic meters per second. 3 Δp represents the initial pressure difference between the upstream and downstream chambers, in MPa; p1(t) and p2(t) are the pressure functions of the upstream and downstream chambers over time, respectively, in MPa; A is the cross-sectional area of ​​the core, in m³. 2 Δt is the test duration, in seconds.

[0080] Step 3d: After the permeability test is completed, open control valves d11, e12 and f13, and use gas booster pump 5 to stabilize the pressure at both ends of core holder 1 and in the upstream chamber 14 and downstream chamber 15 to the required pore pressure for the experiment. Close control valves d11, e12, f13, g16 and h17, and continue the three-phase reaction.

[0081] Step 3e: Repeat steps 3a-3d to test core permeability;

[0082] Step 3f: After the reaction is complete, remove the rock core, dry it, and measure the core porosity and permeability.

[0083] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An experimental apparatus for measuring carbon dioxide-water-rock reaction and core permeability using a pulse method, characterized in that, include: Core holder (1), used to hold core samples; Temperature heating unit for heating core holder (1); A carbon dioxide pressurization unit is used to pressurize carbon dioxide inside the core holder (1); The confining pressure adjustment unit is used to adjust the confining pressure inside the core holder (1); Pressure detection unit, used for pressure detection; The control unit is used to collect and process data provided by the pressure detection unit, as well as to control the temperature heating unit.

2. The experimental apparatus for measuring carbon dioxide-water-rock reaction and core permeability using the pulse method according to claim 1, characterized in that, The confining pressure regulating unit includes a confining pressure tracking pump (2) connected to the core holder (1) via a confining pressure pipeline, and a control valve a (3) is provided on the confining pressure pipeline.

3. The experimental apparatus for measuring carbon dioxide-water-rock reaction and core permeability using the pulse method according to claim 2, characterized in that, The pressure detection unit includes a pressure sensor a(4) for detecting the pressure of the confining pipeline, and the pressure sensor a(4) is connected to the control unit.

4. The experimental apparatus for measuring carbon dioxide-water-rock reaction and core permeability using the pulse method according to claim 1, characterized in that, The carbon dioxide pressurization unit includes a carbon dioxide cylinder (6) and a high-pressure storage tank (7) connected by a gas pressurization pump (5). The gas pressurization pump (5) is equipped with control valves b (8) and c (9) at both ends. The outlet of the high-pressure storage tank (7) is equipped with a pressure regulating valve (10). The pressure regulating valve (10) is located on the pressurization main pipe. The pressurization main pipe is also equipped with a control valve d (11). The pressurization main pipe is connected to the upstream pressurization branch pipe and the downstream pressurization branch pipe. The upstream pressurization branch pipe and the downstream pressurization branch pipe are respectively equipped with control valves e (12) and f (13). The upstream pressurization branch pipe is connected to the upstream chamber (14) through the upstream pipeline. The downstream pressurization branch pipe is connected to the downstream chamber (15) through the downstream pipeline. The other ends of the upstream pipeline and the downstream pipeline are respectively connected to the upstream connection port and the downstream connection port of the core holder (1).

5. The experimental apparatus for measuring carbon dioxide-water-rock reaction and core permeability using the pulse method according to claim 4, characterized in that, The upstream pipeline is connected to the core holder (1) with a control valve g (16), and the downstream pipeline is connected to the core holder (1) with a control valve h (17).

6. The experimental apparatus for measuring carbon dioxide-water-rock reaction and core permeability using the pulse method according to claim 4, characterized in that, The pressure detection unit includes a pressure sensor b (18) for detecting the pressure of the upstream chamber (14), a pressure sensor c (19) for detecting the pressure of the upstream pipeline, a pressure sensor d (20) for detecting the pressure of the downstream pipeline, and a pressure sensor e (21) for detecting the pressure of the downstream chamber (15). The pressure sensors b (18), c (19), d (20) and e (21) are all connected to the control unit.

7. The experimental apparatus for measuring carbon dioxide-water-rock reaction and core permeability using the pulse method according to claim 1, characterized in that, The control unit is a PLC control system (23).

8. The experimental apparatus for measuring carbon dioxide-water-rock reaction and core permeability using the pulse method according to claim 1, characterized in that, The temperature heating unit is an electric heating sleeve (22) fitted onto the core holder (1).

9. An experimental method for measuring carbon dioxide-water-rock reaction and core permeability using a pulse method, characterized in that, Includes the following steps: Step 1: Core sample pretreatment; Step 2: Adjust the pressure and temperature inside the core holder to simulate the three-phase reaction environment of carbon dioxide-water-rock in the underground reservoir; Step 3: Test and calculate core permeability.

10. The experimental method for measuring carbon dioxide-water-rock reaction and core permeability using the pulse method according to claim 9, characterized in that, Step one specifically includes the following: Step 1a: Core the reservoir rock and dry the core. Step 1b: Measure the core porosity and permeability; Step 1c: Prepare formation water; Step 1d: Place the core sample into a vacuum container, pour in formation water, and evacuate to saturate the formation water for 48 hours. Step 1e: Establish the initial water saturation of the core.

11. The experimental method for measuring carbon dioxide-water-rock reaction and core permeability using the pulse method according to claim 9, characterized in that, Step two specifically includes the following: Step 2a: Connect the experimental equipment, place the rock core into the holder, ensure that all connecting pipelines are well sealed, and close all control valves; Step 2b: Open control valve a(3), start confining pressure tracking pump(2), set the pressure difference to 3-5MPa, and apply confining pressure; Step 2c: The PLC control system (23) sets the required temperature for the experiment, and the electric heating mantle (22) starts heating; Step 2d: Open control valve b (8) and control valve c (9), start gas booster pump (5), and store the pressurized carbon dioxide in high pressure tank (7). After pressurization is complete, close control valve b (8) and control valve c (9). Step 2 e: Open control valve d (11), control valve e (12), and control valve f (13), and inject carbon dioxide at the same pressure into the upstream chamber (14) and the downstream chamber (15) through the pressure regulating valve (10); Step 2 f: After the temperature of the core holder (1) rises to the temperature required for the experiment, open control valve g (16) and control valve h (17) and inject carbon dioxide at the same pressure into both ends of the core. After the pressure at both ends of the core holder (1) reaches the required pore pressure and stabilizes, close control valve d (11), control valve e (12), control valve f (13), control valve g (16) and control valve h (17) to allow the three-phase reaction to take place in the core holder (1).

12. The experimental method for measuring carbon dioxide-water-rock reaction and core permeability using the pulse method according to claim 9, characterized in that, Step three specifically includes the following: Step 3a: Open control valve d(11) and control valve e(12), and use the pressure regulating valve to pressurize the upstream chamber separately to create a pressure difference Δp between the upstream and downstream chambers. After pressurization is completed, close control valve d(11) and control valve e(12). Step 3b: Open control valve g (16) and control valve h (17). Due to the pressure difference, carbon dioxide in the upstream chamber (14) gradually flows into the downstream chamber (15), and Δp decreases accordingly. Step 3c: Use a data acquisition device to obtain the pressure change process at both ends of the clamp, and use the pulse permeability calculation formula to calculate the permeability of the rock core at this time. Calculation formula: In the formula, C g ρ is the pore fluid compressibility coefficient of the rock core, in 1 / Pa; μ is the fluid viscosity, in Pa·s; L is the length of the rock core, in meters; V is the volume of the upstream and downstream chambers, in cubic meters per second. 3 Δp represents the initial pressure difference between the upstream and downstream chambers, in MPa; p1(t) and p2(t) are the pressure functions of the upstream and downstream chambers over time, respectively, in MPa; A is the cross-sectional area of ​​the core, in m³. 2 Δt is the test duration, in seconds. Step 3d: After the permeability test is completed, open control valves d (11), e (12) and f (13), and use the gas booster pump (5) to stabilize the pressure at both ends of the core holder (1) and in the upstream chamber (14) and downstream chamber (15) to the required pore pressure for the experiment. Close control valves d (11), e (12), f (13), g (16) and h (17) to continue the three-phase reaction. Step 3e: Repeat steps 3a-3d to test core permeability; Step 3f: After the reaction is complete, remove the rock core, dry it, and measure the core porosity and permeability.

Images