A System and Method for Measuring Relative Permeability under the Coexistence of CO2 and Water in Three Phases

Abstract

The present application belongs to the technical field of permeability measurement, and relates to a system and method for measuring relative permeability under the condition of coexistence of CO2 and water in three phases. The method comprises: obtaining relative permeability data of gaseous CO2 by using a gaseous CO2-water relative permeability experiment; obtaining relative permeability data of liquid CO2 by using a liquid CO2-water relative permeability experiment; normalizing the three-phase saturations of the water phase, gaseous CO2 and liquid CO2 according to the relative permeability data of gaseous CO2 and the relative permeability data of liquid CO2, combining the STONE model, and simultaneously calculating the relative permeability of the water phase to obtain the three-phase relative permeability of the CO2 liquid phase-CO2 gaseous phase-water phase. The present application can accurately calculate the three-phase relative permeability of the CO2 liquid phase-CO2 gaseous phase-water phase.

Description

Technical Field

[0001] This invention belongs to the field of permeability measurement technology, and more specifically, relates to a system and method for measuring relative permeability under the condition of three-phase coexistence of CO2 and water. Background Technology

[0002] CCUS (Carbon Capture, Utilization and Storage) projects capture CO2 emitted from industry and inject it into deep formations for isolation and storage. This process simultaneously enhances oil and gas extraction and promotes resource recovery. As the only effective way to achieve large-scale carbon dioxide emission reduction, CCUS plays an irreplaceable role in mitigating global climate anomalies and controlling the intensification of the greenhouse effect.

[0003] In practical applications of CCUS (Chemical Containment System for US) engineering, CO2 injected into deep formations does not always remain in a single phase. Due to factors such as variations in reservoir depth and differences in pressure and temperature gradients, CO2 undergoes complex phase transitions during its upward migration (especially in the event of leakage). Ultimately, it may coexist with formation water in two phases: liquid CO2 and gaseous CO2, forming a three-phase seepage system of water-liquid CO2-gaseous CO2. However, the physicochemical properties, migration characteristics, and interactions with formation rocks of liquid CO2 and gaseous CO2 are fundamentally different, directly affecting the stability of CO2 sequestration and posing a risk of CO2 leakage.

[0004] Liquid CO2 has high viscosity and density, relatively poor fluidity, slow migration rate in reservoirs, less affected by buoyancy, and tends to spread horizontally in the lower part of the injection layer. Its distribution is stable and controllable, and it is easy to form predictable CO2 plumes, which facilitates the simulation and management of long-term migration paths. Gas CO2, on the other hand, has extremely low viscosity and density, extremely high fluidity, and is significantly affected by buoyancy. It will migrate upwards rapidly and is very easy to leak along channels such as faults, abandoned wells, and formation fractures. Its distribution is difficult to control, and it is easy to produce fingering phenomena that bypass low-permeability areas, leading to premature breakthroughs to non-target layers and significantly increasing the risk of storage failure.

[0005] Although three-phase coexistence systems are a typical scenario in CO2 leakage processes, liquid and gaseous CO2 are generally treated as a single CO2 phase. Measurements and calculations of relative permeability are performed only for the water-CO2 two-phase system (e.g., calculating liquid phase relative permeability based on the Van Genuchten model and gas phase relative permeability based on the Corey model). This completely ignores the impact of the essential differences between the two CO2 phases on the seepage characteristics, resulting in calculation results that fail to accurately reflect the three-phase seepage characteristics under actual operating conditions. This makes it difficult to provide reliable technical support for the safety assessment and leakage risk prevention of CCUS projects. Therefore, there is an urgent need to develop a scheme that can distinguish between liquid and gaseous CO2 and accurately obtain the relative permeability under three-phase coexistence conditions of water-phase CO2 and gaseous CO2. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a system and method for measuring relative permeability under conditions of coexistence of CO2 and water in three phases.

[0007] In a first aspect, the present invention provides a relative permeability measurement system under the condition of three-phase coexistence of CO2 and water, including a gas supply system, a fluid supply system, a core clamping system, a fluid separation and metering system, a data acquisition system and a data analysis system;

[0008] The gas supply system includes a gas phase CO2 supply system and a liquid phase CO2 supply system, which are used to supply liquid phase CO2 to the core and control the injection pressure of the liquid phase CO2;

[0009] The fluid supply system is used to provide aqueous working fluid to the core clamping system and to isolate and protect the working fluid from the drive components.

[0010] Core clamping system is used to fix the core and regulate the core temperature and confining pressure;

[0011] A fluid separation and metering system is used to separate the gas and liquid phases of the fluid permeating from the core and to measure the gas volume and liquid flow rate separately.

[0012] The data acquisition system is used to collect temperature, pressure, and flow rate data of each phase at the core inlet and outlet.

[0013] The data analysis system is used to calculate the relative permeability data of gas phase CO2 and liquid phase CO2 based on the collected temperature, pressure and flow rate data of each phase at the core inlet and outlet. Combined with the STONE model, the CO saturation of the three phases is normalized, and the relative permeability of the water phase is calculated to obtain the three-phase relative permeability of CO liquid phase-CO gas phase-water phase.

[0014] Secondly, this invention provides a relative permeability measurement method based on a relative permeability measurement system under conditions of three-phase coexistence of CO2 and water, including:

[0015] A relative permeability measurement system for CO2 and water in a three-phase coexistence condition was used to conduct a relative permeability experiment of gas phase CO2-water to obtain relative permeability data of gas phase CO2. The relative permeability data of gas phase CO2 includes the relative permeability of gas phase CO2, the saturation of water phase relative to gas phase CO, and the saturation of gas phase CO2.

[0016] A relative permeability measurement system for CO2 and water in a three-phase coexistence condition was used to conduct a relative permeability experiment of liquid phase CO2-water to obtain relative permeability data of liquid phase CO2. The relative permeability data of liquid phase CO2 includes the relative permeability of liquid phase CO2, the saturation of water phase relative to liquid phase CO2, and the saturation of liquid phase CO2.

[0017] Based on the relative permeability data of gaseous CO2 and liquid CO2, and combined with the STONE model, the CO2 saturation of the three phases is normalized, and the relative permeability of the aqueous phase is calculated to obtain the three-phase relative permeability of CO2 liquid phase, CO2 gas phase, and aqueous phase. Based on the above technical solution, the present invention can be further improved as follows.

[0018] Furthermore, the gas phase CO2 supply system includes a gas source container, a main gas valve, a first booster pump, a gas intermediate container, a gas pressure regulating valve before the core sample, a first flow controller, a humidifier, a gas injection flow control valve, a gas pressure regulating valve after the core sample, and a back pressure device.

[0019] The first outlet of the gas source container is connected to the inlet of the first booster pump via a main gas valve; the outlet of the first booster pump is connected to the inlet of the intermediate gas container; one outlet of the intermediate gas container is connected to one end of the first flow controller via a pre-core gas pressure regulating valve, and the other outlet is connected to one inlet of the back pressure device via a post-core gas pressure regulating valve; the other end of the first flow controller is connected to the inlet of the humidification tank; the outlet of the humidification tank is connected to the input end of the core clamping system via a gas injection flow control valve; the other inlet of the back pressure device is connected to the outlet of the core clamping system; and the outlet of the back pressure device is connected to the fluid separation and metering system.

[0020] The liquid-phase CO2 supply system includes a main liquid valve, a second booster pump, a liquid intermediate container, a pre-core liquid pressure regulating valve, a second flow controller, a first liquid injection flow control valve, and a post-core liquid pressure regulating valve.

[0021] The second outlet of the gas source container is connected to the inlet of the second booster pump via a liquid main valve; the outlet of the second booster pump is connected to the inlet of the intermediate liquid container; one outlet of the intermediate liquid container is connected to one end of the second flow controller via a pre-core liquid pressure regulating valve, and the other outlet is connected to one inlet of the back pressure device via a post-core liquid pressure regulating valve; the other end of the second flow controller is connected to the input end of the core clamping system via a first liquid injection flow control valve.

[0022] A first pressure sensor is installed between the first flow controller and the humidification tank; a second pressure sensor is installed between the gas pressure regulating valve after the core and the back pressure device; a third pressure sensor is installed between the gas pressure regulating valve after the core and the back pressure device; and a fourth pressure sensor is installed between the liquid pressure regulating valve before the core and the first liquid injection flow control valve.

[0023] Furthermore, the fluid supply system includes a fluid container, a horizontal flow pump, a displacement fluid intermediate container, a working fluid control valve, a preheating tank, and a second liquid injection flow control valve; the fluid container is connected to the inlet of the displacement fluid intermediate container through the horizontal flow pump; the outlet of the displacement fluid intermediate container is connected to the inlet of the preheating tank through the working fluid control valve; and the outlet of the preheating tank is connected to the input end of the core clamping system through the second liquid injection flow control valve.

[0024] Furthermore, the core clamping system includes a confining pressure pump, a confining pressure valve, a constant temperature chamber, and a core clamp; the core clamp is installed inside the constant temperature chamber; the inlet of the core clamp is connected to the outlet of the gas supply system and the outlet of the fluid supply system; the inlet of the confining pressure pump is connected to one end of the constant temperature chamber, and the outlet of the confining pressure pump is connected to the other end of the core clamp through the confining pressure valve; the outlet of the core clamp is equipped with a fifth pressure sensor and a first temperature sensor.

[0025] Furthermore, a four-way valve is installed between the outlet of the gas phase CO2 supply system, the outlet of the liquid phase CO2 supply system, the outlet of the fluid supply system and the inlet of the core clamping system; a sixth pressure sensor and a second temperature sensor are installed between the four-way valve and the core clamping system.

[0026] Furthermore, the fluid separation and metering system includes a gas-liquid separator, a drying cylinder, a balance, and a gas-liquid flow meter; the output end of the core clamping system is connected to the inlet of the drying cylinder through the gas-liquid separator; the gas-liquid separator is mounted on the balance; and the gas-liquid flow meter is mounted at the outlet of the drying cylinder.

[0027] Furthermore, a relative permeability experiment of gas-phase CO2-water was conducted to obtain relative permeability data of gas-phase CO2, including:

[0028] Assume the water saturation of the core is . The gas phase CO2 saturation is , No. The mass of the water-bearing core in the group experiment was The dry core mass is The effective pore volume of the core is The density of simulated formation water in saturated core samples at the measured temperature is: The water saturation of each experimental core sample is calculated and expressed as:

[0029] ;

[0030] The calculated CO2 saturation in the gas phase is expressed as:

[0031] ;

[0032] Assume the effective permeability of gas-phase CO2 is The value of atmospheric pressure is The gas phase CO2 flow rate is The viscosity of gaseous CO2 at the measured temperature is The core length is The cross-sectional area of ​​the core is The core inlet pressure is The effective permeability of the aqueous phase is Water flow rate is The viscosity of water at the measured temperature is The core outlet pressure is The relative permeability of gas-phase CO2 is The effective permeability of the gas phase under bound water state is The saturation level of the water phase relative to the CO2 gas phase is ,but:

[0033] ;

[0034] ;

[0035] ;

[0036] The saturation of the water phase relative to the CO2 gas phase is calculated and expressed as:

[0037] .

[0038] Furthermore, a relative permeability experiment of liquid CO2-water was conducted to obtain relative permeability data of liquid CO2, including:

[0039] Assume the water saturation of the core is . The liquid phase CO2 saturation is , No. The mass of the water-bearing core in the group experiment was The dry core mass is The effective pore volume of the core is The density of simulated formation water in saturated core samples at the measured temperature is: The water saturation of each experimental core sample is calculated and expressed as:

[0040] ;

[0041] The CO2 saturation in the liquid phase is calculated and expressed as:

[0042] ;

[0043] Assume the effective permeability of liquid CO2 is The value of liquid phase CO2 flow rate is The viscosity of liquid CO2 at the measured temperature is The core length is The cross-sectional area of ​​the core is The core inlet pressure is The effective permeability of the aqueous phase is Water flow rate is The viscosity of water at the measured temperature is The core outlet pressure is The relative permeability of liquid CO2 is The effective permeability of the liquid phase under bound water state is The saturation level of the water phase relative to the liquid CO2 phase is ,but:

[0044] ;

[0045] ;

[0046] ;

[0047] The saturation of the water phase relative to the liquid CO2 phase is calculated and expressed as:

[0048] .

[0049] Furthermore, the CO2 saturation of the three phases is normalized, and the relative permeability of the aqueous phase is calculated to obtain the three-phase relative permeability of CO2 liquid phase-CO2 gas phase-water phase, including:

[0050] Let the normalized gas phase CO2 saturation be... Normalized liquid phase CO2 saturation is Normalized water phase saturation is The relative permeability of gas-phase CO2 is The relative permeability of liquid CO2 is The relative permeability of the water phase is The gas phase CO2 saturation is The liquid phase CO2 saturation is The water phase saturation is The bound water saturation is ,but:

[0051] ;

[0052] ;

[0053] ;

[0054] ;

[0055] Let the saturation of the water phase relative to the CO2 in the gas phase be . The saturation level of the water phase relative to the liquid CO2 phase is The relative permeability of the aqueous phase is calculated and expressed as:

[0056] .

[0057] The beneficial effects of the present invention are as follows: The present invention designs a device that can simultaneously perform two experiments: the relative permeability experiment of gas phase CO2-water and the relative permeability experiment of liquid phase CO2-water. The device can provide three fluids, namely water phase, liquid phase CO2 and gas phase CO2, for the experiment, which simplifies the experimental steps and can accurately calculate the three-phase relative permeability of CO2 liquid phase-CO2 gas phase-water phase. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the relative permeability measurement system under the condition of three-phase coexistence of CO2 and water provided in Embodiment 1 of the present invention.

[0059] Figure 2 A schematic diagram illustrating the specific implementation of a relative permeability measurement system under conditions of three-phase coexistence of CO2 and water;

[0060] Figure 3 This is a schematic diagram of the relative permeability measurement method under the condition of three-phase coexistence of CO2 and water provided in Embodiment 2 of the present invention.

[0061] Figure 4 The flowchart of the experimental and calculation process provided in Embodiment 2 of the present invention.

[0062] Icons: 101-Gas source container; 102-Main gas valve; 103-First booster pump; 104-Intermediate gas container; 105-Gas pressure regulating valve before core; 106-First flow controller; 107-Humidifier tank; 108-Gas injection flow control valve; 109-Gas pressure regulating valve after core; 110-Back pressure device; 111-Main liquid valve; 112-Second booster pump; 113-Intermediate liquid container; 114-Liquid pressure regulating valve before core; 115-Second flow controller; 116-First liquid injection flow control valve; 117-Liquid pressure regulating valve after core; 201-Fluid container; 202-Adjustable flow pump; 203-Displacement fluid Intermediate container; 204-Working fluid control valve; 205-Preheating tank; 206-Second liquid injection flow control valve; 301-Containing pressure pump; 302-Containing pressure valve; 303-Constant temperature chamber; 304-Core holder; 401-Four-way valve; 501-First pressure sensor; 502-Second pressure sensor; 503-Third pressure sensor; 504-Fourth pressure sensor; 505-Fifth pressure sensor; 506-Sixth pressure sensor; 601-First temperature sensor; 602-Second temperature sensor; 701-Gas-liquid separator; 702-Drying cylinder; 703-Balance; 704-Gas-liquid flow meter. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0064] Example 1

[0065] As an example, see the attached document. Figure 1 As shown, in order to solve the above-mentioned technical problems, this embodiment provides a relative permeability measurement under CO2 three-phase coexistence conditions, including a gas supply system, a fluid supply system, a core clamping system, a fluid separation and metering system, a data acquisition system and a data analysis system;

[0066] The gas supply system includes a gas phase CO2 supply system and a liquid phase CO2 supply system, which are used to supply liquid phase CO2 to the core and control the injection pressure of the liquid phase CO2;

[0067] The fluid supply system is used to provide the aqueous working fluid to the core clamping system and to isolate and protect the working fluid from the drive components.

[0068] Core clamping system is used to fix the core and regulate the core temperature and confining pressure;

[0069] A fluid separation and metering system is used to separate the gas and liquid phases of the fluid permeating from the core and to measure the gas volume and liquid flow rate separately.

[0070] The data acquisition system is used to collect temperature, pressure, and flow rate data of each phase at the core inlet and outlet.

[0071] The data analysis system is used to calculate the relative permeability data of gas phase CO2 and liquid phase CO2 based on the collected temperature, pressure and flow rate data of each phase at the core inlet and outlet. Combined with the STONE model, the CO2 saturation of the three phases is normalized, and the relative permeability of the water phase is calculated to obtain the relative permeability of the three phases: liquid phase, gas phase, and water phase.

[0072] Optional, as shown in the appendix Figure 2 As shown, the gas phase CO2 supply system includes a gas source container 101, a main gas valve 102, a first booster pump 103, a gas intermediate container 104, a core pre-gas pressure regulating valve 105, a first flow controller 106, a humidifier tank 107, a gas injection flow control valve 108, a core post-gas pressure regulating valve 109, and a back pressure device 110.

[0073] The first outlet of the gas source container 101 is connected to the inlet of the first booster pump 103 via the gas main valve 102; the outlet of the first booster pump 103 is connected to the inlet of the intermediate gas container 104; one outlet of the intermediate gas container 104 is connected to one end of the first flow controller 106 via the core pre-gas pressure regulating valve 105, and the other outlet is connected to one inlet of the back pressure device 110 via the core post-gas pressure regulating valve 109; the other end of the first flow controller 106 is connected to the inlet of the humidification tank 107; the outlet of the humidification tank 107 is connected to the input end of the core clamping system via the gas injection flow control valve 108; the other inlet of the back pressure device 110 is connected to the outlet of the core clamping system; the outlet of the back pressure device 110 is connected to the fluid separation metering system.

[0074] The liquid phase CO2 supply system includes a main liquid valve 111, a second booster pump 112, a liquid intermediate container 113, a pre-core liquid pressure regulating valve 114, a second flow controller 115, a first liquid injection flow control valve 116, and a post-core liquid pressure regulating valve 117.

[0075] The second outlet of the gas source container 101 is connected to the inlet of the second booster pump 112 via the liquid main valve 111; the outlet of the second booster pump 112 is connected to the inlet of the intermediate liquid container 113; one outlet of the intermediate liquid container 113 is connected to one end of the second flow controller 115 via the core pre-liquid pressure regulating valve 114, and the other outlet is connected to one inlet of the back pressure device 110 via the core post-liquid pressure regulating valve 117; the other end of the second flow controller 115 is connected to the input end of the core clamping system via the first liquid injection flow control valve 116.

[0076] A first pressure sensor 501 is installed between the first flow controller 106 and the humidification tank 107; a second pressure sensor 502 is installed between the core post gas pressure regulating valve 109 and the back pressure device 110; a third pressure sensor 503 is installed between the core post gas pressure regulating valve 109 and the back pressure device 110; and a fourth pressure sensor 504 is installed between the core pre liquid pressure regulating valve 114 and the first liquid injection flow control valve 116.

[0077] In practical applications, one outlet of the gas source container 101 is controlled by the main gas valve 102. CO2 gas passes through the first booster pump 103 and is stored in the intermediate gas container 104 for later use. A portion of the gas in the intermediate gas container 104 passes through the pre-core gas pressure regulating valve 105 and the first flow controller 106, and then the pressure is measured by the first pressure sensor 501. The gas then enters the humidification tank 107 for humidification and is finally prepared to be supplied to the core through the gas injection flow control valve 108 and the four-way valve 401. The other portion of the CO2 gas in the intermediate gas container 104 passes through the post-core gas pressure regulating valve 109 and the second pressure sensor 502, and then enters the back pressure device 110 to control the pressure after the core. During the experimental gas injection process, it is necessary to ensure that the CO2 injected into the core is gaseous CO2, and the CO2 output from the core is also gaseous CO2, while maintaining a pressure difference.

[0078] In practical applications, another outlet of the gas source container 101 is controlled by the main liquid valve 111. CO2 gas is converted into liquid CO2 by the second booster pump 112 and stored in the intermediate liquid container 113 for later use. A portion of the gas in the intermediate liquid container 113 passes through the pre-core liquid pressure regulating valve 114 and the second flow controller 115, and then the pressure is measured by the third pressure sensor 503. Finally, it passes through the first liquid injection flow control valve 116 and the four-way valve 401, ready to be supplied to the core. The other portion of the liquid CO2 in the intermediate liquid container 113 passes through the post-core liquid pressure regulating valve 117 and the fourth pressure sensor 504, and then enters the back pressure device 110, which is responsible for controlling the pressure after the core. During the experimental injection of liquid CO2, it is necessary to ensure that the pressure difference exists before and after the injection, and that the CO2 injected into the core is liquid CO2, and the CO2 output from the core is also liquid CO2.

[0079] This invention combines two experimental devices for liquid-phase CO2 water displacement and gas-phase CO2 water displacement, designing a device that can simultaneously perform two experiments. This device can provide three fluids—water phase, liquid phase CO2, and gas phase CO2—for the experiment, simplifying the experimental steps.

[0080] Optional, as shown in the appendix Figure 2As shown, the fluid supply system includes a fluid container 201, a horizontal flow pump 202, a displacement fluid intermediate container 203, a working fluid control valve 204, a preheating tank 205, and a second liquid injection flow control valve 206. The fluid container 201 is connected to the inlet of the displacement fluid intermediate container 203 through the horizontal flow pump 202. The outlet of the displacement fluid intermediate container 203 is connected to the inlet of the preheating tank 205 through the working fluid control valve 204. The outlet of the preheating tank 205 is connected to the input end of the core clamping system through the second injection flow control valve 206.

[0081] In practical applications, the outlet of fluid container 201 is controlled by a horizontal flow pump 202 to pump the displacing fluid (such as distilled water) into the intermediate displacing fluid container 203. The pressure of the displacing fluid causes the working fluid (such as formation water) in the intermediate container 203 to flow. The working fluid then enters the preheating tank 205 through the working fluid control valve 204 for initial heating. Finally, it is prepared for core loading through the second liquid injection flow control valve 206 and the four-way valve 401. The intermediate fluid container isolates the working fluid from the horizontal flow pump 202 during liquid displacement. The pressure of the distilled water driven by the horizontal flow pump 202 displaces the working fluid, preventing damage to the horizontal flow pump 202 caused by the easy crystallization of the working fluid (such as formation water and oil). The preheating tank 205 is added to the displacing fluid to bring it to the core temperature in advance, preventing it from affecting the core temperature during displacement.

[0082] Optional, as shown in the appendix Figure 2 As shown, the core clamping system includes a confining pressure pump 301, a confining pressure valve 302, a constant temperature chamber 303, and a core clamp 304; the core clamp 304 is installed inside the constant temperature chamber 303; the inlet of the core clamp 304 is connected to the outlet of the gas supply system and the outlet of the fluid supply system; the inlet of the confining pressure pump 301 is connected to one end of the constant temperature chamber 303, and the outlet of the confining pressure pump 301 is connected to the other end of the core clamp 304 through the confining pressure valve 302; the outlet of the core clamp 304 is equipped with a fifth pressure sensor 505 and a first temperature sensor 601.

[0083] In practical applications, the core holder 304 is responsible for fixing the core and applying confining pressure using the confining pressure pump 301. The core holder 304 is located in the constant temperature chamber 303, which can regulate the temperature change of the core. A temperature sensor and a pressure sensor are set on both sides of the core holder 304, which are used to measure the temperature and pressure of the injected fluid, as well as the temperature and pressure of the fluid passing through the core.

[0084] By reducing the size of the thermostatic chamber 303 to near the core and encasing it, the core temperature can be regulated more effectively. Pressure and temperature sensors are installed on both sides of the core clamping system, allowing for more precise understanding and control of the core's temperature and pressure, which is more conducive to preventing a phase change in the CO2 within the core.

[0085] Optional, as shown in the appendix Figure 2 As shown, a four-way valve 401 is installed between the outlet of the gas phase CO2 supply system, the outlet of the liquid phase CO2 supply system, the outlet of the fluid supply system and the inlet of the core clamping system; a sixth pressure sensor 506 and a second temperature sensor 602 are installed between the four-way valve 401 and the core clamping system.

[0086] Optional, as shown in the appendix Figure 2 As shown, the fluid separation and metering system includes a gas-liquid separator 701, a drying cylinder 702, a balance 703, and a gas-liquid flow meter 704; the output end of the core clamping system is connected to the inlet of the drying cylinder 702 through the gas-liquid separator 701; the gas-liquid separator 701 is mounted on the balance 703; and the gas-liquid flow meter 704 is mounted at the outlet of the drying cylinder 702.

[0087] The fluid separation and metering system is responsible for separating CO2 and liquid two-phase fluids that permeate from the rock core, and measuring the gas flow rate (measuring the gas flow rate of gaseous CO2 and calculating the flow rate of liquid CO2 based on density and flow rate) and liquid flow rate respectively. Finally, the data is recorded and calculated through the data acquisition system.

[0088] This invention designs a device that can simultaneously perform two experiments: the relative permeability experiment of gas phase CO2-water and the relative permeability experiment of liquid phase CO2-water. The device can provide three fluids for the experiment: water phase, liquid phase CO2, and gas phase CO2, which simplifies the experimental steps and can accurately calculate the three-phase relative permeability of CO2 liquid phase, CO2 gas phase, and water phase.

[0089] Example 2

[0090] Based on the same principles as the system shown in Embodiment 1 of the present invention, as illustrated in the appendix. Figure 3 As shown, embodiments of the present invention also provide a relative permeability measurement method based on a relative permeability measurement system under conditions of three-phase coexistence of CO2 and water, including:

[0091] A relative permeability measurement system for CO2 and water in a three-phase coexistence condition was used to conduct a relative permeability experiment of gas phase CO2-water to obtain relative permeability data of gas phase CO2. The relative permeability data of gas phase CO2 includes the relative permeability of gas phase CO2, the saturation of water phase relative to gas phase CO2, and the saturation of gas phase CO2.

[0092] A relative permeability measurement system for CO2 and water in a three-phase coexistence condition was used to conduct a relative permeability experiment of liquid phase CO2-water to obtain relative permeability data of liquid phase CO2. The relative permeability data of liquid phase CO2 includes the relative permeability of liquid phase CO2, the saturation of water phase relative to liquid phase CO2, and the saturation of liquid phase CO2.

[0093] Based on the relative permeability data of gaseous CO2 and liquid CO2, and combined with the STONE model, the CO2 saturation of the three phases is normalized, and the relative permeability of the aqueous phase is calculated to obtain the three-phase relative permeability of CO2 liquid phase, CO2 gas phase, and aqueous phase.

[0094] As attached Figure 4 The flowchart shown illustrates the experimental and calculation process. First, the relative permeability of the two phases is measured.

[0095] The relative permeability experiment of gas-phase CO2-water was conducted using a relative permeability measurement system under the condition of three-phase coexistence of CO2 and water. The specific steps are as follows:

[0096] (1) Measurement of basic parameters:

[0097] Measure and record the mass, length, and diameter of the dried core.

[0098] The density and viscosity of each working fluid used in the experiment are obtained by measurement or by referring to a table;

[0099] (2) Measure the effective pore volume of the core

[0100] Place the core sample into the buffer tank of the vacuum device and evacuate it for more than half an hour using a vacuum pump.

[0101] Saturate the core with a working fluid (such as simulated formation water);

[0102] Weigh the rock sample after saturation with simulated formation water, and calculate the effective pore volume and porosity; assume the mass of the dry rock sample is... The mass of the rock sample after saturation with simulated formation water is The density of the simulated formation water in the saturated rock sample at the measured temperature is... The effective pore volume of the rock sample is The total volume of the rock sample is The porosity of the rock sample is ,but:

[0103] ;

[0104] ;

[0105] (3) Measure the bound water saturation of the core.

[0106] Prepare the core holder, clean and dry the front and rear plungers, and use a bulb syringe to check the inlet and outlet channels to ensure they are unobstructed.

[0107] The rock sample saturated with simulated formation water is loaded into the core holder and the confining pressure is set. This step requires ensuring that the confining pressure of the core is greater than the injection pressure of the core.

[0108] Open the main gas valve and the first booster pump to allow the experimental gas (CO2) to enter the intermediate gas container for later use; open the gas pressure regulating valve before the core sample to allow the gas to pass through the first flow controller, the first pressure sensor and the humidifier; open the gas injection flow control valve to allow the gas to enter the four-way valve.

[0109] After opening the core sample, the gas pressure regulating valve allows the gas to pass through the second pressure sensor and enter the back pressure device. The back pressure device needs to be adjusted during the experiment.

[0110] Humidified gas was injected into the core for gas-phase CO2 water displacement, and then the displacement rate was gradually increased until no more water was discharged. The bound water saturation was set at [value missing]. The effective pore volume of the rock sample is The volume of water displaced from the rock is The bound water saturation of the core was established and calculated using the following formula:

[0111] ;

[0112] (4) Measure the CO2 permeability in the bound water state.

[0113] After the restored rock samples with bound water saturation and restored wettability were loaded into the core holder and displaced by gaseous CO2 to 10 times the pore volume, the effective permeability of gaseous CO2 was measured.

[0114] Rock samples were displaced with gaseous CO2. After the pressure or flow rate stabilized, the effective permeability of gaseous CO2 was measured. Three consecutive measurements were performed, with a relative deviation of less than 3%. The effective permeability of gaseous CO2 under bound water conditions was assumed to be... Atmospheric pressure is The gas phase CO2 flow rate is The viscosity of gaseous CO2 at the measured temperature is The length of the rock sample is The cross-sectional area of ​​the rock sample is The rock sample inlet pressure is Calculate the effective permeability of gas-phase CO2 under bound water saturation:

[0115] ;

[0116] (5) Measure the liquid phase CO2 permeability in the bound water state.

[0117] Restoration rock samples with established bound water saturation and restored wettability were loaded into a core holder and displaced with liquid CO2 to 10 times the pore volume. The effective permeability of liquid CO2 was then measured. After displacing the rock samples with liquid CO2 and stabilizing the pressure or flow rate, the effective permeability of liquid CO2 was measured three times consecutively, with a relative deviation of less than 3%. Let the effective permeability of liquid CO2 under bound water conditions be denoted as... The liquid phase CO2 flow rate is The viscosity of liquid CO2 at the measured temperature is The length of the rock sample is The cross-sectional area of ​​the rock sample is The rock sample inlet pressure is The rock sample outlet pressure is Calculate the effective CO2 permeability in the liquid phase under bound water saturation:

[0118] ;

[0119] The relative permeability experiment of gas phase CO2-water includes the following steps:

[0120] Place the core sample into the buffer tank of the vacuum device and evacuate it for more than half an hour using a vacuum pump.

[0121] The core was saturated with a working fluid (simulated formation water in this experiment);

[0122] Prepare the core holder: Clean and dry the front and rear plungers, and use a clean bulb syringe to check the inlet and outlet channels to ensure they are unobstructed;

[0123] The rock sample saturated with simulated formation water is loaded into the core holder and the confining pressure is set. This step requires ensuring that the confining pressure of the core is greater than the injection pressure of the core.

[0124] Inject the working fluid (the fluid used to displace the core) into the intermediate displacement container.

[0125] Turn on the horizontal flow pump to allow the displacement fluid (distilled water) to enter the intermediate displacement fluid container, so as to drive the working fluid (simulated formation water) to flow. Open the working fluid control valve to allow the working fluid to enter the preheating tank. Open the second liquid injection flow control valve to allow the liquid to enter the four-way valve.

[0126] Open the main CO2 valve and the first booster pump to allow the experimental gas (CO2) to enter the intermediate gas container for later use. Open the gas pressure regulating valve before the core sample to allow the gas phase CO2 to pass through the first flow controller, the first pressure sensor, and the humidifier. Open the gas injection flow control valve to allow the gas to enter the four-way valve.

[0127] After opening the core gas pressure regulating valve, the gas enters the back pressure device through the second pressure sensor. During the experiment, it is necessary to adjust the core gas pressure regulating valve, the core gas pressure regulating valve and the back pressure device to ensure that the pressure in front of the core is greater than the pressure behind the core. It is also necessary to ensure that the CO2 before injection is in the gas phase and the CO2 flowing out of the core is also in the gas phase.

[0128] Under the condition of constant total injection rate, working fluid and gaseous CO2 were injected into the rock sample in a certain ratio. The following are the proportions of liquid (simulated formation water) and gaseous CO2 in the injected core fluid. A total of 7 sets of experiments were set up, and the experimental results of relative permeability of gaseous CO2-water are shown in Table 1.

[0129] Table 1. Experimental results of relative permeability of gas phase CO2-water.

[0130]

[0131] Liquid and gaseous CO2 were injected into the core according to the ratio of the corresponding experimental group. When the flow stabilized, the gas and water pressure, temperature and flow rate at the inlet and outlet were measured.

[0132] Core samples were extracted and the mass of the water-bearing rock samples was determined. (No. (mass of water-bearing rock samples from the group experiment).

[0133] Assume the water saturation of the core is . The gas phase CO2 saturation is , No. The mass of the water-bearing core in the group experiment was The dry core mass is The effective pore volume of the core is The density of simulated formation water in saturated core samples at the measured temperature is: The water saturation of each experimental core sample is calculated and expressed as:

[0134] ;

[0135] The calculated CO2 saturation in the gas phase is expressed as:

[0136] ;

[0137] Assume the effective permeability of gas-phase CO2 is The value of atmospheric pressure is The gas phase CO2 flow rate is The viscosity of gaseous CO2 at the measured temperature is The core length is The cross-sectional area of ​​the core is The core inlet pressure is The effective permeability of the aqueous phase is Water flow rate is The viscosity of water at the measured temperature is The core outlet pressure is The relative permeability of gas-phase CO2 is The effective permeability of the gas phase under bound water state is The saturation level of the water phase relative to the CO2 gas phase is ,but:

[0138] ;

[0139] ;

[0140] ;

[0141] The saturation of the water phase relative to the CO2 gas phase is calculated and expressed as:

[0142] .

[0143] The relative permeability of gas phase CO2-water was calculated at various water saturation (CO2 saturation) levels, and the corresponding curves were plotted.

[0144] The relative permeability experiment of liquid phase CO2-water includes the following steps:

[0145] Place the core sample into the buffer tank of the vacuum device and evacuate it for more than half an hour using a vacuum pump.

[0146] The core was saturated with a working fluid (simulated formation water in this experiment);

[0147] Prepare the core holder: the front and rear plungers must be thoroughly cleaned and dried; use a clean bulb syringe to check the inlet and outlet channels to ensure they are unobstructed;

[0148] The rock sample saturated with simulated formation water is loaded into the core holder and the confining pressure is set. This step requires ensuring that the confining pressure of the core is greater than the injection pressure of the core.

[0149] Inject the working fluid (the liquid used to displace the core) into the intermediate container of the displacement fluid.

[0150] Turn on the horizontal flow pump to allow the displacement fluid (distilled water) to enter the intermediate displacement fluid container, so as to drive the working fluid (simulated formation water) to flow. Open the working fluid control valve to allow the working fluid to enter the preheating tank. Open the second liquid injection flow control valve to allow the liquid to enter the four-way valve.

[0151] Open the main liquid CO2 valve and the second booster pump to pressurize the experimental gas (CO2) into liquid CO2 and allow it to enter the intermediate container for use. Open the liquid pressure regulating valve before the core sample to allow the liquid CO2 to pass through the second flow controller and the third pressure sensor. Open the second liquid injection flow control valve to allow the liquid CO2 to enter the four-way valve.

[0152] After opening the core, the liquid pressure regulating valve allows the liquid CO2 to enter the back pressure device through the fourth pressure sensor. During the experiment, it is necessary to adjust the liquid pressure regulating valve before and after the core, as well as the back pressure device, to ensure that the pressure before the core is greater than the pressure after the core. It is also necessary to ensure that the CO2 before injection is in the liquid phase and the CO2 flowing out of the core is also in the liquid phase.

[0153] Under the condition of constant total injection rate, the working fluid and liquid CO2 were injected into the rock sample in a certain ratio. The following is the ratio of liquid (simulated formation water) and liquid CO2 to the injected core fluid. A total of 7 sets of experiments were set up, as shown in Table 2, which shows the experimental results of the relative permeability of liquid phase CO2-water.

[0154] Table 2. Experimental results of relative permeability of liquid phase CO2-water.

[0155]

[0156] Liquid and liquid CO2 were injected into the core according to the ratio of the corresponding experimental group. When the flow stabilized, the gas and water pressure, temperature and flow rate at the inlet and outlet were measured.

[0157] Core samples were extracted and the mass of the water-bearing rock samples was determined. (No. (mass of water-bearing rock samples from the group experiment).

[0158] Assume the water saturation of the core is . The liquid phase CO2 saturation is , No. The mass of the water-bearing core in the group experiment was The dry core mass is The effective pore volume of the core is The density of simulated formation water in saturated core samples at the measured temperature is: The water saturation of each experimental core sample is calculated and expressed as:

[0159] ;

[0160] The CO2 saturation in the liquid phase is calculated and expressed as:

[0161] ;

[0162] Assume the effective permeability of liquid CO2 is The value of liquid phase CO2 flow rate is The viscosity of liquid CO2 at the measured temperature is The core length is The cross-sectional area of ​​the core is The core inlet pressure is The effective permeability of the aqueous phase is Water flow rate is The viscosity of water at the measured temperature is The core outlet pressure is The relative permeability of liquid CO2 is The effective permeability of the liquid phase under bound water state is The saturation level of the water phase relative to the liquid CO2 phase is ,but:

[0163] ;

[0164] ;

[0165] ;

[0166] The saturation of the water phase relative to the liquid CO2 phase is calculated and expressed as:

[0167] .

[0168] In the relative permeability experiment of gas phase CO2-water, the saturation of each water phase was obtained. and gas phase CO2 saturation Relative permeability of water phase below and relative permeability of gas phase CO2 To distinguish them, the relative permeability of this water phase is... Written as This is the gas phase CO2 saturation. The relative permeability of the water phase below.

[0169] In the relative permeability experiment of liquid phase CO2-water, the saturation of each water phase was obtained. and liquid phase CO2 saturation Relative permeability of water phase below and the relative permeability of liquid CO2 To distinguish them, the relative permeability of this water phase is... Written as This is the liquid phase CO2 saturation. The relative permeability of the water phase below.

[0170] The CO2 saturation of the three phases is normalized, and the relative permeability of the aqueous phase is calculated to obtain the three-phase relative permeability of CO2 liquid phase-CO2 gas phase-water phase, including:

[0171] Let the normalized gas phase CO2 saturation be... Normalized liquid phase CO2 saturation is Normalized water phase saturation is The relative permeability of gas-phase CO2 is The relative permeability of liquid CO2 is The relative permeability of the water phase is The gas phase CO2 saturation is The liquid phase CO2 saturation is The water phase saturation is The bound water saturation is ,but:

[0172] ;

[0173] ;

[0174] ;

[0175] ;

[0176] Let the saturation of the water phase relative to the CO2 in the gas phase be . The saturation level of the water phase relative to the liquid CO2 phase is The relative permeability of the aqueous phase is calculated and expressed as:

[0177] .

[0178] From this data, a three-phase diagram of relative permeability under the condition of three-phase coexistence of water, liquid-phase CO2, and gas-phase CO2 can be plotted. The data at various saturation levels in the experiment can then be used to construct the diagram. and By calculating the data, the isotonic curve of gas-phase CO2 can be plotted; the data at various saturations in the experiment can be used to plot the isotonic curve. and By calculating the data, an isotonic curve of CO2 in the liquid phase can be plotted; the values ​​at various saturations in the experiment can be used to plot the isotonic curve. and The data can be used to calculate and plot the isotonic curve of the aqueous phase.

[0179] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A system for measuring relative permeability under the condition of three-phase coexistence of CO2 and water, characterized in that, It includes a gas supply system, a fluid supply system, a core clamping system, a fluid separation and metering system, a data acquisition system, and a data analysis system; The gas supply system includes a gas phase CO2 supply system and a liquid phase CO2 supply system, which are used to supply liquid phase CO2 to the core and control the injection pressure of the liquid phase CO2; The fluid supply system is used to provide the aqueous working fluid to the core clamping system and to isolate and protect the working fluid from the drive components. Core clamping system is used to fix the core and regulate the core temperature and confining pressure; A fluid separation and metering system is used to separate the gas and liquid phases of fluid permeating from the core and to measure the gas volume and liquid flow rate separately. The data acquisition system is used to collect temperature, pressure, and flow rate data of each phase at the inlet and outlet of the core sample. The data analysis system is used to calculate the relative permeability data of gas phase CO2 and liquid phase CO2 based on the collected temperature, pressure and flow rate data of each phase at the core inlet and outlet. Combined with the STONE model, the CO2 saturation of the three phases is normalized, and the relative permeability of the water phase is calculated to obtain the relative permeability of the three phases: liquid phase, gas phase, and water phase.

2. The relative permeability measurement system under the three-phase coexistence of CO2 and water as described in claim 1, characterized in that, The gas phase CO2 supply system includes a gas source container (101), a gas main valve (102), a first booster pump (103), a gas intermediate container (104), a core pre-gas pressure regulating valve (105), a first flow controller (106), a humidifier (107), a gas injection flow control valve (108), a core post-gas pressure regulating valve (109), and a back pressure device (110). The first outlet of the gas source container (101) is connected to the inlet of the first booster pump (103) through the gas main valve (102); the outlet of the first booster pump (103) is connected to the inlet of the intermediate gas container (104); one outlet of the intermediate gas container (104) is connected to one end of the first flow controller (106) through the core pre-gas pressure regulating valve (105), and the other outlet is connected to one inlet of the back pressure device (110) through the core post-gas pressure regulating valve (109); the other end of the first flow controller (106) is connected to the inlet of the humidification tank (107); the outlet of the humidification tank (107) is connected to the input end of the core clamping system through the gas injection flow control valve (108); the other inlet of the back pressure device (110) is connected to the outlet of the core clamping system; the outlet of the back pressure device (110) is connected to the fluid separation metering system. The liquid phase CO2 supply system includes a main liquid valve (111), a second booster pump (112), a liquid intermediate container (113), a pre-core liquid pressure regulating valve (114), a second flow controller (115), a first liquid injection flow control valve (116), and a post-core liquid pressure regulating valve (117). The second outlet of the gas source container (101) is connected to the inlet of the second booster pump (112) through the liquid main valve (111); the outlet of the second booster pump (112) is connected to the inlet of the intermediate liquid container (113); one outlet of the intermediate liquid container (113) is connected to one end of the second flow controller (115) through the core pre-liquid pressure regulating valve (114), and the other outlet is connected to one inlet of the back pressure device (110) through the core post-liquid pressure regulating valve (117); the other end of the second flow controller (115) is connected to the input end of the core clamping system through the first liquid injection flow control valve (116); A first pressure sensor (501) is provided between the first flow controller (106) and the humidification tank (107); a second pressure sensor (502) is provided between the core post gas pressure regulating valve (109) and the back pressure device (110); a third pressure sensor (503) is provided between the core post gas pressure regulating valve (109) and the back pressure device (110); and a fourth pressure sensor (504) is provided between the core pre liquid pressure regulating valve (114) and the first liquid injection flow control valve (116).

3. The relative permeability measurement system under the condition of three-phase coexistence of CO2 and water as described in claim 1, characterized in that, The fluid supply system includes a fluid container (201), a horizontal flow pump (202), a displacement fluid intermediate container (203), a working fluid control valve (204), a preheating tank (205), and a second liquid injection flow control valve (206). The fluid container (201) is connected to the inlet of the displacement fluid intermediate container (203) through the horizontal flow pump (202). The outlet of the displacement fluid intermediate container (203) is connected to the inlet of the preheating tank (205) through the working fluid control valve (204). The outlet of the preheating tank (205) is connected to the input end of the core clamping system through the second liquid injection flow control valve (206).

4. The relative permeability measurement system under the condition of three-phase coexistence of CO2 and water as described in claim 1, characterized in that, The core clamping system includes a confining pressure pump (301), a confining pressure valve (302), a constant temperature chamber (303), and a core clamp (304); the core clamp (304) is installed inside the constant temperature chamber (303); the inlet of the core clamp (304) is connected to the outlet of the gas supply system and the outlet of the fluid supply system; the inlet of the confining pressure pump (301) is connected to one end of the constant temperature chamber (303), and the outlet of the confining pressure pump (301) is connected to the other end of the core clamp (304) through the confining pressure valve (302); the outlet of the core clamp (304) is equipped with a fifth pressure sensor (505) and a first temperature sensor (601).

5. The relative permeability measurement system under the condition of three-phase coexistence of CO2 and water as described in claim 1, characterized in that, A four-way valve (401) is installed between the outlet of the gas phase CO2 supply system, the outlet of the liquid phase CO2 supply system, the outlet of the fluid supply system and the inlet of the core clamping system; a sixth pressure sensor (506) and a second temperature sensor (602) are installed between the four-way valve (401) and the core clamping system.

6. The relative permeability measurement system under the condition of three-phase coexistence of CO2 and water as described in claim 1, characterized in that, The fluid separation and metering system includes a gas-liquid separator (701), a drying cylinder (702), a balance (703), and a gas-liquid flow meter (704); the output end of the core clamping system is connected to the inlet of the drying cylinder (702) through the gas-liquid separator (701); the gas-liquid separator (701) is installed on the balance (703); and the gas-liquid flow meter (704) is installed at the outlet of the drying cylinder (702).

7. A method for measuring relative permeability based on the relative permeability measurement system under the three-phase coexistence condition of CO2 and water as described in claim 1, characterized in that, include: Using the relative permeability measurement system for the coexistence of CO2 and water as described in claim 1, a relative permeability experiment of gas phase CO2-water was conducted to obtain relative permeability data of gas phase CO2; the relative permeability data of gas phase CO2 includes the relative permeability of gas phase CO2, the relative permeability of water phase relative to the saturation of gas phase CO2, and the saturation of gas phase CO2. The relative permeability of liquid phase CO2-water was measured using the relative permeability measurement system for the three-phase coexistence of CO2 and water as described in claim 1, and the relative permeability data of liquid phase CO2 were obtained. The relative permeability data for liquid CO2 includes the relative permeability of liquid CO2, the relative permeability of the water phase relative to the saturation of liquid CO2, and the saturation of liquid CO2. Based on the relative permeability data of gaseous CO2 and liquid CO2, and combined with the STONE model, the CO2 saturation of the three phases is normalized, and the relative permeability of the aqueous phase is calculated to obtain the three-phase relative permeability of CO2 liquid phase, CO2 gas phase, and aqueous phase.

8. The relative permeability measurement method according to claim 7, characterized in that, A relative permeability experiment of gas phase CO2-water was conducted to obtain the relative permeability data of gas phase CO2, including: Assume the water saturation of the core is . The gas phase CO2 saturation is , No. The mass of the water-bearing core in the group experiment was The dry core mass is The effective pore volume of the core is The density of simulated formation water in saturated core samples at the measured temperature is: The water saturation of each experimental core sample is calculated and expressed as: ； The calculated CO2 saturation in the gas phase is expressed as: ； Assume the effective permeability of gas-phase CO2 is The value of atmospheric pressure is The gas phase CO2 flow rate is The viscosity of gaseous CO2 at the measured temperature is The core length is The cross-sectional area of ​​the core is The core inlet pressure is The effective permeability of the aqueous phase is Water flow rate is The viscosity of water at the measured temperature is The core outlet pressure is The relative permeability of gas-phase CO2 is The effective permeability of the gas phase under bound water state is The relative permeability of the water phase relative to the CO2 saturation of the gas phase is ,but: ； ； ； The relative permeability of the water phase relative to the CO2 saturation of the gas phase is calculated and expressed as: 。 9. The relative permeability measurement method according to claim 7, characterized in that, A relative permeability experiment of liquid CO2-water was conducted to obtain the relative permeability data of liquid CO2, including: Assume the water saturation of the core is . The liquid phase CO2 saturation is , No. The mass of the water-bearing core in the group experiment was The dry core mass is The effective pore volume of the core is The density of simulated formation water in saturated core samples at the measured temperature is: The water saturation of each experimental core sample is calculated and expressed as: ； The CO2 saturation in the liquid phase is calculated and expressed as: ； Assume the effective permeability of liquid CO2 is The value of liquid phase CO2 flow rate is The viscosity of liquid CO2 at the measured temperature is The core length is The cross-sectional area of ​​the core is The core inlet pressure is The effective permeability of the aqueous phase is Water flow rate is The viscosity of water at the measured temperature is The core outlet pressure is The relative permeability of liquid CO2 is The effective permeability of the liquid phase under bound water state is The relative permeability of the aqueous phase relative to the CO2 saturation of the liquid phase is ,but: ； ； ； The relative permeability of the aqueous phase relative to the CO2 saturation of the liquid phase is calculated and expressed as: 。 10. The relative permeability measurement method according to claim 7, characterized in that, The CO2 saturation of the three phases is normalized, and the relative permeability of the aqueous phase is calculated to obtain the three-phase relative permeability of CO2 liquid phase-CO2 gas phase-water phase, including: Let the normalized gas phase CO2 saturation be... Normalized liquid phase CO2 saturation is Normalized water phase saturation is The relative permeability of gas-phase CO2 is The relative permeability of liquid CO2 is The relative permeability of the water phase is The gas phase CO2 saturation is The liquid phase CO2 saturation is The water phase saturation is The bound water saturation is ,but: ； ； ； ； Assume the relative permeability of the water phase relative to the CO2 saturation of the gas phase is 100%. The relative permeability of the aqueous phase relative to the CO2 saturation of the liquid phase is The relative permeability of the aqueous phase is calculated and expressed as: 。

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