Oil reservoir relative permeability and oil displacement testing device and experimental method

Abstract

The invention relates to the technical field of oil and gas reservoir experiments, in particular to an oil reservoir relative permeability and oil displacement testing device and an experimental method. The oil reservoir relative permeability and oil displacement testing device comprises a clamping testing module, a displacement module, a metering module and a terminal processing module, the clamping testing module comprises a resistivity rock core clamping device, a resistivity tester and a nuclear magnetic resonance spectrometer, and oil-gas-water displacement experiments are conducted on rock cores through the displacement module; the measuring module records pressure change at two ends of the core holder and three-phase flow during an experiment, and the terminal processing module calibrates a relation curve of water saturation and resistivity and a relation curve of oil saturation and nuclear magnetic signals based on results of resistivity test and nuclear magnetic resonance test. According to the experimental method, oil-gas-water displacement experiments are carried out respectively, and the relative permeability and oil displacement efficiency of the oil-gas-water three phases are measured. The three-phase seepage state under the real abandoned oil reservoir condition can be better simulated, and the three-phase saturation degree can be monitored in real time.

Description

Technical Field

[0001] This invention relates to the field of oil and gas reservoir experimental technology, and in particular to an oil reservoir phase permeability and oil displacement testing device and experimental method. Background Technology

[0002] Abandoned oil reservoirs are oil and gas reservoirs that can no longer be commercially developed after extraction. The management and treatment of abandoned oil reservoirs must comply with environmental protection requirements, including well sealing, sealing, and monitoring measures to ensure that groundwater resources and the environment are not polluted. Abandoned oil reservoir carbon sequestration technology involves storing carbon dioxide (CO2) in abandoned oil reservoirs. The technology of capturing and injecting gases into abandoned oil reservoirs aims to reduce greenhouse gas emissions into the atmosphere, thereby storing carbon dioxide gas in underground oil reservoirs for a long time and mitigating global climate change.

[0003] Relative permeability and displacement efficiency are important data in oil and gas reservoir development. Currently, experimental equipment for measuring three-phase relative permeability and displacement efficiency during carbon burial in abandoned oil reservoirs mainly includes resistivity, CT, NMR, and chromatography. Methods primarily include steady-state and unsteady-state displacement experiments, capillary force methods, and numerical simulations. Patent CN104777086A discloses a steady-state flow method for determining supercritical fluid displacement. Apparatus and methods for emulsion three-phase permeability, including obtaining supercritical fluid permeability at different saturations by performing dual-energy CT scanning on a one-dimensional core model. The relative permeability of three-phase emulsion fluids. However, the core model of this method cannot well simulate the distribution of core pore structure and seepage law; the invention patent with publication number CN111827995B discloses a method for calculating the permeability of overpressure conglomerate reservoirs based on nuclear magnetic resonance, including introducing the pore structure index m and overpressure property index Pi obtained from the core analysis of overpressure conglomerate reservoirs into the SDR permeability calculation model to calculate its permeability K. The influence of overpressure on permeability K is included in the calculation of permeability, realizing a precise and quantitative method for calculating its permeability. However, this calculation method does not clearly and quantitatively calculate the saturation of oil, gas and water three phases; the invention patent with publication number CN 113309501A discloses an experimental method for determining the water-drive oil efficiency of fresh loose sandstone samples, including establishing standard curves of simulated oil, simulated formation water content and nuclear magnetic resonance signal quantity to obtain the oil displacement efficiency under different displacement ratios and water saturation, realizing rapid, non-destructive and quantitative identification of fluids in the sample, solving the problem of long cycle for obtaining oil displacement efficiency during water-drive of sandstone samples. However, this method has limitations in studying the flow and distribution of oil, gas, and water phases in the core. Summary of the Invention

[0004] The purpose of this invention is to provide a reservoir phase permeation and oil displacement testing device and experimental method to solve the problems in the prior art that cannot accurately simulate the three-phase permeation state under real abandoned oil reservoir conditions and that the three-phase oil displacement efficiency cannot be effectively monitored.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention discloses a reservoir phase permeability and oil displacement testing device, comprising: The clamping test module includes a resistivity core holder, and a resistivity tester and a nuclear magnetic resonance spectrometer connected to the resistivity core holder. The displacement module includes a multi-port valve connected to the input port of the resistivity core holder, and a water phase displacement unit, an oil phase displacement unit, and a gas phase displacement unit respectively connected to the multi-port valve. An inlet pressure sensor is provided on the connection route between the resistivity core holder and the multi-port valve. The metering module includes an oil-gas-water separator connected to the output port of the resistivity core holder, and a gas metering unit, an oil phase metering unit, and a water phase metering unit respectively connected to the oil-gas-water separator. An outlet pressure sensor is provided on the connection route between the resistivity core holder and the oil-gas-water separator. The terminal processing module is connected to the resistivity tester and is used to measure the water saturation and resistivity signal values ​​of the core during water flooding, and to calibrate the relationship curve between water saturation and resistivity. The terminal processing module is also connected to the nuclear magnetic resonance spectrometer and is used to measure the oil saturation and nuclear magnetic resonance signal of the core during oil flooding, and to calibrate the relationship curve between oil saturation and nuclear magnetic resonance signal.

[0006] Optionally, the reservoir relative permeability and oil displacement testing device further includes a back pressure module and a formation simulation module. The back pressure module includes a back pressure pump connected to the output port of the resistivity core holder, and a back pressure valve disposed on the connection route between the back pressure pump and the resistivity core holder. The back pressure valve is located on the connection route between the outlet pressure sensor and the oil-gas-water separator. The formation simulation module includes a temperature chamber, a temperature controller, and a flow pump. The resistivity core holder is installed inside the temperature chamber, and the temperature controller is connected to the temperature chamber. The flow pump is connected to the input port of the resistivity core holder.

[0007] Optionally, the aqueous phase displacement unit includes an aqueous phase liquid bottle, an aqueous phase displacement pump, and an aqueous phase intermediate container connected in sequence. The aqueous phase intermediate container is connected to the multi-way valve, and an aqueous phase pressure sensor is provided on the connection line between the aqueous phase intermediate container and the multi-way valve. The oil phase displacement unit includes an oil phase liquid bottle, an oil phase displacement pump, and an oil phase intermediate container connected in sequence. The oil phase intermediate container is connected to the multi-way valve, and an oil phase pressure sensor is installed on the connection line between the oil phase intermediate container and the multi-way valve. The gas phase displacement unit includes a gas phase liquid bottle, a gas phase displacement pump, and a gas phase intermediate container connected in sequence. The gas phase intermediate container is connected to the multi-way valve, and a gas phase pressure sensor is installed on the connection line between the gas phase intermediate container and the multi-way valve.

[0008] Optionally, the oil phase metering unit includes an oil phase collection container and an oil phase electronic balance disposed at the bottom of the oil phase collection container, and the aqueous phase metering unit includes an aqueous phase collection container and an aqueous phase electronic balance disposed at the bottom of the aqueous phase collection container.

[0009] This invention also discloses an experimental method, which uses the above-mentioned reservoir relative permeability and oil displacement testing device to conduct testing experiments. The experimental method includes: Obtain core samples from the target oilfield, determine the basic parameters of the core samples, and treat the core samples with saturated formation water. Water drive experiments were conducted on the core samples at the experimental temperature. After the water drive stabilized, the absolute permeability of the water phase was measured. The changes in the flow rate of the water phase and the changes in the resistivity of the core samples were recorded. A model for determining water saturation based on the relationship between water saturation and resistivity was established. Oil-flooding and water-flooding experiments were conducted on the core samples at the experimental temperature. After the oil-flooding stabilized, the absolute permeability of the oil phase under the condition of bound water saturation was measured. The changes in the flow rate of the oil phase and the changes in the nuclear magnetic resonance signal of the core samples were recorded. A model for determining the oil saturation by correlating the oil saturation with the nuclear magnetic resonance signal was established. Gas-drive and oil-drive experiments were conducted on the core samples at the experimental temperature. After the gas drive stabilized, the absolute permeability of the gas phase under residual oil saturation conditions was measured. The oil discharge rate of the gas-drive oil was recorded to determine the oil displacement efficiency. The distribution of the three-phase saturation during gas-drive was determined based on the water saturation calculation model and the oil saturation calculation model. Three-phase flow experiments were conducted on the core samples at the experimental temperature. After the three-phase flow stabilized, the effective permeability of each phase was measured. The relative permeability of the three phases was calculated based on the measured effective and absolute permeability. The resistivity and nuclear magnetic resonance signal changes of the core samples during the three-phase flow were recorded to determine the relative permeability of the three phases at different saturation levels.

[0010] Optionally, the method for determining the basic parameters of the core sample and saturating the core sample with formation water includes: The obtained core samples were pretreated by washing and drying, and the length, cross-sectional area and external volume of the pretreated core samples were measured. The pretreated core samples were dried, and the dry weight of the core samples after drying was recorded. The dried core samples were then subjected to vacuuming and alcohol saturation treatment, and the wet weight of the core samples after alcohol saturation was recorded. Based on the recorded dry and wet weights, the pore volume and porosity of the core samples were determined. The formulas for calculating the pore volume and porosity are as follows:

[0011]

[0012] In the formula, This refers to the pore volume of the core sample. It is heavy when wet. For dry weight, The density of alcohol, The porosity of the core sample. The external volume of the core sample; The core samples saturated with alcohol were dried and vacuumed in sequence, and formation water containing deuterium water and mineral salts was prepared. The vacuumed core samples were then saturated with a predetermined amount of formation water.

[0013] Optionally, it also includes methods for determining the absolute permeability of the aqueous phase and establishing models for calculating water saturation: At the experimental temperature, a predetermined amount of formation water was used to displace the saturated formation water in the core sample at a constant rate and flow rate. After the water flow rate at the end of the core sample stabilized, the water flow rate and the pressure difference between the two ends of the core sample were recorded. The absolute permeability of the water phase was then calculated. The formula for calculating the absolute permeability of the water phase is as follows:

[0014] In the formula, The absolute permeability of the aqueous phase. The flow rate of the aqueous phase. The viscosity of water, The length of the core sample. The cross-sectional area of ​​the core sample. This represents the pressure difference between the two ends of the core sample; Record the changes in the flow rate of the aqueous phase and the resistivity changes of the core samples during water flooding, and establish a water saturation calculation model that correlates water saturation with resistivity. The expression for the water saturation calculation model is as follows:

[0015] In the formula, Water saturation The resistivity of the formation water. The resistivity is the measured value of the core sample. and This is the resistivity correction factor.

[0016] Optionally, it also includes methods for determining the absolute permeability of the oil phase under bound water saturation conditions and for establishing a model for determining oil saturation: At the experimental temperature, formation water in the core sample was displaced by formation crude oil at a predetermined displacement rate, and bound water saturation was established. After water ceased to flow from the end of the core sample, the flow rate of the oil phase and the pressure difference between the two ends of the core sample were recorded. The absolute permeability of the oil phase under bound water saturation conditions was calculated. The formulas for calculating bound water saturation and absolute permeability of the oil phase are as follows:

[0017]

[0018] In the formula, To restrict water saturation, The volume of water discharged by oil-driven water. The absolute permeability of the oil phase. The flow rate of the oil phase. The viscosity of the oil; The changes in oil phase flow rate and NMR signal of the core samples during oil-driven water discharge were recorded, and an oil saturation determination model correlating oil saturation with NMR signal was established. The expression for the oil saturation determination model is as follows:

[0019] In the formula, Oil saturation The measured NMR signal intensity of the core sample. The measured nuclear magnetic relaxation time of the core sample is given. The time interval for nuclear magnetic resonance (NMR) imaging. The NMR signal intensity is the value of the core sample when the oil phase is fully saturated. This is the nuclear magnetic relaxation time when the oil phase in the core sample is fully saturated.

[0020] Optionally, it also includes methods for determining the absolute permeability of the gas phase under residual oil saturation conditions and for determining the three-phase saturation distribution during gas-driven oil production. At the experimental temperature, carbon dioxide gas was used to displace the formation crude oil in the core sample at a preset constant pressure, and residual oil saturation was established. After no more oil was discharged from the end of the core sample, the gas flow rate, the amount of oil discharged by the gas-driven oil, the amount of water discharged by the gas-driven oil, and the pressure difference between the two ends of the core sample were recorded. The absolute permeability of the gas phase under the residual oil saturation condition was calculated. The formulas for calculating the residual oil saturation and the absolute permeability of the gas phase are as follows:

[0021]

[0022] In the formula, Residual oil saturation, This refers to the water displacement of gas-driven oil. This refers to the amount of oil discharged during gas-driven oil production. The absolute permeability of the gas phase. The flow rate of the oil phase. Atmospheric pressure, For the viscosity of the gas, and These represent the pressures at both ends of the core sample; The oil displacement efficiency is calculated based on the oil discharge rate and the pore volume of the core sample. The formula for calculating the oil displacement efficiency is as follows:

[0023] In the formula, For oil displacement efficiency; The water saturation and oil saturation during gas-driven oil injection are calculated using the water saturation calculation model and the oil saturation calculation model, respectively. The gas saturation during gas-driven oil injection is then calculated based on the water saturation and oil saturation during the gas-driven oil injection process. The formula for calculating the gas saturation is as follows:

[0024] In the formula, For gas saturation, This refers to the oil saturation level during gas-driven oil production. The water saturation level during gas-driven oil production; Based on the calculated oil displacement efficiency, and the oil saturation, water saturation, and gas saturation during gas-driven oil displacement, the relationship between oil displacement efficiency and the three-phase saturation distribution is analyzed and determined.

[0025] Optionally, it also includes measuring the relative permeability of the three phases at different saturations: At the experimental temperature, carbon dioxide gas was used to continuously displace the core sample at a preset constant pressure, and formation crude oil and formation water were simultaneously injected into the core sample in a preset ratio to establish a three-phase seepage steady state inside the core sample. The effective permeability of each phase during three-phase flow is calculated using the absolute permeability calculation formula for each phase. The corresponding relative permeability is then calculated based on the effective and absolute permeability of each phase. The formula for calculating the relative permeability is as follows:

[0026] In the formula, The relative permeability of a single phase. For single-phase effective permeability, This represents the absolute permeability of a single phase. The injection ratio of formation crude oil and formation water was adjusted, and the resistivity and nuclear magnetic resonance signal changes of the core samples were recorded at different injection ratios. The water saturation and oil saturation during three-phase flow were calculated according to the water saturation calculation model and the oil saturation calculation model, respectively. The gas saturation during three-phase flow was calculated according to the gas saturation calculation formula. Based on the calculated relative permeability and saturation of the three phases, the relationship between the distribution of relative permeability and saturation of the three phases isopermeability is drawn for different injection ratios of formation crude oil and formation water.

[0027] Compared with the prior art, the reservoir relative permeability and oil displacement testing device and experimental method provided in the embodiments of the present invention have the following advantages: By setting up a clamping test module, a displacement module, a metering module, and a terminal processing module, the resistivity core holder clamps the core, and the displacement module conducts experiments on water drive, oil-water drive, gas-oil drive, and three-phase flow. Combining resistivity testing and nuclear magnetic resonance (NMR) technology, based on the electrical characteristics of the core, the resistivity test determines the water saturation of the core, and the NMR test measures the content of hydrogen nuclei in the oil phase to reflect the abundance of oil in the core pores, which is visually reflected in the form of NMR T2 spectrum. The peak area of ​​the T2 spectrum is used to quantitatively reflect the crude oil saturation, and then the relative permeability and oil displacement efficiency of the oil, gas, and water phases are determined, and their relationship with the distribution of the three-phase saturation is determined. This allows for better simulation of the three-phase flow state under real abandoned oil reservoir conditions, and the three-phase saturation can be monitored in real time. The experimental device has high precision and a wide range of applications. Attached Figure Description

[0028] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a schematic block diagram of the overall structure of the reservoir phase permeation and oil displacement testing device provided in an embodiment of the present invention; Figure 2 This is a schematic block diagram of the unfolded structure of each module in the reservoir phase permeation and oil displacement testing device provided in the embodiment of the present invention; Figure 3A graph showing the relationship between water saturation and resistivity calibration provided in an embodiment of the present invention; Figure 4 The relationship curve between oil saturation and NMR signal calibration is provided for embodiments of the present invention; Figure 5 The three-phase isotonic diagram provided for an embodiment of the present invention.

[0029] The markings in the attached diagram are as follows: 1. Clamping test module; 11. Resistivity core holder; 111. Inlet pressure sensor; 112. Outlet pressure sensor; 12. Resistivity meter; 13. Nuclear magnetic resonance spectrometer; 2. Displacement module; 21. Aqueous phase displacement unit; 211. Aqueous phase liquid bottle; 212. Aqueous phase displacement pump; 213. Aqueous phase intermediate container; 214. Aqueous phase pressure sensor; 22. Oil phase displacement unit; 221. Oil phase liquid bottle; 222. Oil phase displacement pump; 223. Oil phase intermediate container; 224. Oil phase pressure sensor; 23. Gas phase displacement unit; 2 31. Gas-liquid bottle; 232. Gas-phase displacement pump; 233. Gas-phase intermediate container; 3. Metering module; 31. Oil-gas-water separator; 32. Gas metering unit; 33. Oil-phase metering unit; 331. Oil-phase collection container; 332. Oil-phase electronic balance; 34. Water-phase metering unit; 341. Water-phase collection container; 342. Water-phase electronic balance; 4. Terminal processing module; 5. Multi-port valve; 7. Back pressure module; 71. Back pressure pump; 72. Back pressure valve; 8. Formation simulation module; 81. Temperature chamber; 82. Temperature controller; 83. Flow pump.

[0030] Specific real-time methods It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0031] This invention discloses a reservoir phase permeability and oil displacement testing device, such as... Figure 1 and Figure 2As shown, the system includes a clamping and testing module 1, a displacement module 2, a metering module 3, and a terminal processing module 4. The clamping and testing module 1 includes a resistivity core holder 11, and a resistivity meter 12 and a nuclear magnetic resonance spectrometer 13 connected to the resistivity core holder 11. The displacement module 2 includes a multi-port valve 5 connected to the input port of the resistivity core holder 11, and a water phase displacement unit 21, an oil phase displacement unit 22, and a gas phase displacement unit 23 respectively connected to the multi-port valve 5. An inlet pressure sensor 111 is installed on the connection route between the resistivity core holder 11 and the multi-port valve 5. The metering module 3 includes an oil-gas-water separator 31 connected to the output port of the resistivity core holder 11, and a gas metering unit 32, an oil phase metering unit 33, and a water phase metering unit 34 respectively connected to the oil-gas-water separator 31. An outlet pressure sensor 112 is installed on the connection route between the resistivity core holder 11 and the oil-gas-water separator 31. Terminal processing module 4 is connected to resistivity meter 12 to measure the water saturation and resistivity signal values ​​of the core during water flooding, and to calibrate the relationship curve between water saturation and resistivity. Terminal processing module 4 is also connected to nuclear magnetic resonance spectrometer 13 to measure the oil saturation and NMR signal of the core during oil flooding, and to calibrate the relationship curve between oil saturation and NMR signal.

[0032] Through the implementation of the above-mentioned reservoir phase permeability and oil displacement testing device, the resistivity core holder 11 holds the core, and the water phase displacement unit 21, oil phase displacement unit 22, and gas phase displacement unit 23 respectively conduct water-drive, oil-drive-water, gas-drive-oil, and three-phase permeation experiments on the core. The pressure at both ends of the resistivity core holder 11 is monitored in real time by the inlet pressure sensor 111 and the outlet pressure sensor 112, and the flow rates of the three phases during the experiment are recorded by the gas metering unit 32, oil phase metering unit 33, and water phase metering unit 34 respectively. Combined with resistivity testing and verification... Magnetic resonance technology, based on the electrical characteristics of the core, uses a resistivity meter 12 to determine the water saturation of the core and a nuclear magnetic resonance spectrometer 13 to measure the content of hydrogen nuclei in the oil phase to reflect the abundance of oil in the core pores. This is reflected visually in the form of nuclear magnetic resonance T2 spectrum. The peak area of ​​the T2 spectrum is used to quantitatively reflect the oil saturation. Then, the relative permeability and oil displacement efficiency of the three phases of oil, gas and water are determined, and their relationship with the distribution of the three phase saturation is determined. This allows for better simulation of the three-phase seepage state under real abandoned oil reservoir conditions, and the three-phase saturation can be monitored in real time.

[0033] Furthermore, the reservoir relative permeability and oil displacement testing device also includes a backpressure module 7 and a formation simulation module 8. The backpressure module 7 includes a backpressure pump 71 connected to the output port of the resistivity core holder 11, and a backpressure valve 72 located on the connection route between the backpressure pump 71 and the resistivity core holder 11. The backpressure valve 72 is located on the connection route between the outlet pressure sensor 112 and the oil-gas-water separator 31. The formation simulation module 8 includes a temperature chamber 81, a temperature controller 82, and a horizontal flow pump 83. The resistivity core holder 11 is housed within the temperature chamber 81, and the temperature controller 82 is connected to the temperature chamber 81. The horizontal flow pump 83 is connected to the input port of the resistivity core holder 11.

[0034] By implementing the aforementioned reservoir relative permeability and oil displacement testing device, effective control of reservoir formation pressure can be achieved. Specifically, the back pressure pump 71 in the back pressure module 7 provides stable back pressure to the resistivity core holder 11, maintaining the pressure across the holder at a set value, thereby establishing a constant pressure difference and simulating the pressure environment in the reservoir formation. Simultaneously, the back pressure valve 72, located on the connection route between the outlet pressure sensor 112 and the oil-gas-water separator 31, can monitor and adjust the back pressure in real time, further ensuring the stability and reliability of the testing process. Furthermore, the setup of the temperature chamber 81, temperature controller 82, and advection pump 83 in the formation simulation module 8 allows the device to simulate the temperature and flow conditions in the reservoir formation, more realistically reflecting the actual situation of the reservoir, thus improving the accuracy and reliability of relative permeability and oil displacement testing.

[0035] Further, the aqueous phase displacement unit 21 includes an aqueous phase liquid bottle 211, an aqueous phase displacement pump 212, and an aqueous phase intermediate container 213 connected in sequence. The aqueous phase intermediate container 213 is connected to a multi-way valve 5, and an aqueous phase pressure sensor 214 is installed on the connection line between the aqueous phase intermediate container 213 and the multi-way valve 5. The oil phase displacement unit 22 includes an oil phase liquid bottle 221, an oil phase displacement pump 222, and an oil phase intermediate container 223 connected in sequence. The oil phase intermediate container 223 is connected to a multi-way valve 5, and an oil phase pressure sensor 224 is installed on the connection line between the oil phase intermediate container 223 and the multi-way valve 5. The gas phase displacement unit 23 includes a gas phase liquid bottle 231, a gas phase displacement pump 232, and a gas phase intermediate container 233 connected in sequence. The gas phase intermediate container 233 is connected to a multi-way valve 5, and a gas phase pressure sensor is installed on the connection line between the gas phase intermediate container 233 and the multi-way valve 5.

[0036] Through the implementation of the above-mentioned reservoir phase permeation and oil displacement testing device, the intermediate water phase container 213 in the water phase displacement unit 21 can store aqueous liquid, and the aqueous liquid is displaced into the resistivity core holder 11 by the water phase displacement pump 212, thereby achieving water phase displacement. The water phase pressure sensor 214 can monitor the water phase pressure between the intermediate water phase container 213 and the resistivity core holder 11 in real time, ensuring the stability and accuracy of the displacement process. The intermediate oil phase container 223 in the oil phase displacement unit 22 can store oil phase liquid, and the oil phase liquid is displaced into the resistivity core holder 11 by the oil phase displacement pump 222, thereby achieving oil phase displacement. The oil phase pressure sensor 224 can monitor the oil phase pressure between the intermediate oil phase container 223 and the resistivity core holder 11 in real time, ensuring the stability and accuracy of the displacement process. The intermediate gas phase container 233 in the gas phase displacement unit 23 can store gaseous liquid and displace it into the resistivity core holder 11 via the gas phase displacement pump 232, thus achieving gas phase displacement. A gas phase pressure sensor can monitor the gas phase pressure between the intermediate gas phase container 233 and the resistivity core holder 11 in real time, ensuring the stability and accuracy of the displacement process. The multi-port valve 5 allows for independent displacement and control of the water, oil, and gas phases, enabling more precise study of the transport and displacement patterns of multiphase flows in rocks, and allowing for combinations of various displacement methods for a more comprehensive study of the displacement behavior of multiphase flows in rocks. Furthermore, the intermediate container acts as a buffer and stabilizes pressure, reducing pressure fluctuations during displacement, ensuring the stability and accuracy of the displacement, and ensuring the continuous operation of the displacement process. The amount of displacing liquid can be adjusted according to experimental requirements.

[0037] Furthermore, the oil phase metering unit 33 includes an oil phase collection container 331 and an oil phase electronic balance 332 disposed at the bottom of the oil phase collection container 331, and the water phase metering unit 34 includes a water phase collection container 341 and a water phase electronic balance 342 disposed at the bottom of the water phase collection container 341.

[0038] By implementing the aforementioned reservoir phase permeation and oil displacement testing device, the oil phase electronic balance 332 and the water phase electronic balance 342 can accurately measure the mass of the oil and water phases during the displacement process. This allows for precise control of the oil and water phase volumes during displacement, facilitating accurate research into the proportional changes of the oil and water phases and their impact on the oil displacement effect. Furthermore, by monitoring the mass changes of the oil and water phases in real time, displacement strategies can be optimized, such as adjusting displacement rate and pressure parameters, to improve oil displacement efficiency.

[0039] This invention also discloses an experimental method, which uses the above-mentioned reservoir relative permeability and oil displacement testing device to conduct testing experiments. The experimental method includes: Obtain core samples from the target oilfield, determine the basic parameters of the core samples, and treat the core samples with saturated formation water. Water drive experiments were conducted on core samples at the experimental temperature. After the water drive stabilized, the absolute permeability of the water phase was measured. The changes in the flow rate of the water phase and the resistivity of the core samples were recorded. A model for determining water saturation, which is related to water saturation and resistivity, was established. Oil-flooding and water-flooding experiments were conducted on core samples at the experimental temperature. After the oil-flooding stabilized, the absolute permeability of the oil phase under the condition of bound water saturation was measured. The changes in the flow rate of the oil phase and the changes in the NMR signal of the core samples were recorded. A model for determining oil saturation by correlating oil saturation with NMR signal was established. Gas-driven oil-driven experiments were conducted on core samples at the experimental temperature. After the gas drive stabilized, the absolute permeability of the gas phase under residual oil saturation conditions was measured. The oil discharge rate of the gas-driven oil was recorded to determine the oil displacement efficiency. The distribution of three-phase saturation during gas-driven oil was determined based on the water saturation calculation model and the oil saturation calculation model. Three-phase flow experiments were conducted on core samples at the experimental temperature. After the three-phase flow stabilized, the effective permeability of each phase was measured. The relative permeability of the three phases was calculated based on the measured effective and absolute permeability. The resistivity and nuclear magnetic resonance signal changes of the core samples during the three-phase flow were recorded to determine the relative permeability of the three phases at different saturation levels.

[0040] As described above, the present invention was conducted under the following preferred conditions, with the target oil field having a surface crude oil density of 0.985 g / cm³. 3 The viscosity is 6.17 mPa·s; the density of formation water in the original formation water is 1.009 g / cm³. 3 Viscosity 0.477 mPa·s, salinity 33429 mg / L, formation water type is The core sample measured a diameter of 2.5 cm, a length of 5 cm, and an average permeability of 150 mD. The displacing gas used was 99.99% pure. The experimental conditions were a temperature of 60 ℃ and a pressure of 10 MPa. Figure 3 This is a graph showing the relationship between water saturation and resistivity under the experimental conditions. Figure 4 The graph shows the relationship between oil saturation and NMR signal calibration under the experimental conditions.

[0041] Furthermore, methods for determining the basic parameters of core samples and saturating them with formation water include: The obtained core samples were pretreated by washing and drying, and the length, cross-sectional area and external volume of the pretreated core samples were measured. The pretreated core samples were dried, and the dry weight of the core samples was recorded. The dried core samples were then subjected to vacuum treatment and saturated with alcohol, and the wet weight of the core samples after alcohol saturation was recorded. Based on the recorded dry and wet weights, the pore volume and porosity of the core samples were determined. The formulas for calculating pore volume and porosity are as follows:

[0042]

[0043] In the formula, This refers to the pore volume of the core sample. It is heavy when wet. For dry weight, The density of alcohol, The porosity of the core sample. The external volume of the core sample; After being saturated with alcohol, the core samples were dried and vacuumed in sequence. Formation water containing deuterium water and mineral salts was prepared, and the vacuumed core samples were saturated with a predetermined amount of formation water.

[0044] As mentioned above, drying, vacuuming, and alcohol saturation treatment are all preferably performed for more than 12 hours. Furthermore, the determination of basic parameters for the core sample also includes measuring its permeability according to the standard "SY / T 5336—2006 Core Analysis Methods". The steps are as follows: connect the gas permeability testing device and check its airtightness; place the core sample into the resistivity core holder 11 in the predetermined direction and connect the pipeline; apply a confining pressure of 5 MPa, set the gas inlet pressure to 0.1 MPa, and the gas flow volume to 1 mL; open the gas cylinder to allow gas to flow, and wait for the gas flow to stabilize before preparing for the experiment; press the suction bulb of the soap foam flowmeter to release foam, and start timing as the gas pushes the foam from the 0 mark to the 1 mL volume mark, stopping the timing; after stabilization, measure three consecutive sets of data, recording the temperature during the experiment; calculate the gas permeability of the core sample based on the measured parameters. In addition, formation water containing deuterium water and mineral salts is used to shield the nuclear magnetic resonance signal of the water. When the core sample is loaded into the resistivity core holder 11, fluorinated oil that does not respond to the nuclear magnetic resonance test can be inserted between the rubber sleeve and the outer shell of the resistivity core holder 11 to prevent interference with the results of the nuclear magnetic resonance instrument 13 in testing the oil saturation.

[0045] Furthermore, it also includes methods for determining the absolute permeability of the aqueous phase and establishing models for calculating water saturation: At the experimental temperature, a pre-prepared amount of formation water was used to displace the saturated formation water in the core sample at a constant rate (preferably 0.1 mL / min). After the water flow rate at the end of the core sample stabilized, the cumulative displacement was increased to a preferred 3 PV to fully saturate the sample. The water flow rate and the pressure difference between the two ends of the core sample were recorded, and the absolute permeability of the water phase was calculated. The formula for calculating the absolute permeability of the water phase is as follows:

[0046] In the formula, The absolute permeability of the aqueous phase. The flow rate of the aqueous phase. The viscosity of water, The length of the core sample. The cross-sectional area of ​​the core sample. This represents the pressure difference between the two ends of the core sample; Record the changes in water flow rate and resistivity of core samples during water flooding, and establish a water saturation calculation model that correlates water saturation with resistivity. The expression for the water saturation calculation model is as follows:

[0047] In the formula, Water saturation The resistivity of the formation water. The resistivity is the measured value of the core sample. and This is the resistivity correction factor.

[0048] Furthermore, it also includes methods for determining the absolute permeability of the oil phase under bound water saturation conditions and establishing a model for calculating oil saturation: At the experimental temperature, formation water in the core sample was displaced by formation crude oil at a constant rate (preferably 0.1 mL / min) to establish bound water saturation. Once the cumulative oil displacement reached a preferred 3 PV and no more water was discharged from the end of the core sample, the oil flow stabilized. The flow rate of the oil phase and the pressure difference between the two ends of the core sample were recorded. The absolute permeability of the oil phase under bound water saturation conditions was calculated. The formulas for calculating bound water saturation and the absolute permeability of the oil phase are as follows:

[0049]

[0050] In the formula, To restrict water saturation, The volume of water discharged by oil-driven water. The absolute permeability of the oil phase. The flow rate of the oil phase. The viscosity of the oil; The changes in oil phase flow rate and NMR signal of core samples during oil-driven water discharge were recorded. A model for determining oil saturation based on the correlation between oil saturation and NMR signal was established. The expression for the oil saturation determination model is as follows:

[0051] In the formula, Oil saturation The measured NMR signal intensity of the core sample. The measured nuclear magnetic relaxation time of the core sample is given. The time interval for nuclear magnetic resonance (NMR) imaging. The NMR signal intensity is the value of the core sample when the oil phase is fully saturated. This is the nuclear magnetic relaxation time when the oil phase in the core sample is fully saturated.

[0052] As mentioned above, the oil saturation is obtained based on the peak area of ​​the calibrated NMR T2 spectrum.

[0053] Furthermore, it also includes methods for determining the absolute permeability of the gas phase under residual oil saturation conditions and for determining the three-phase saturation distribution during gas-driven oil production. At the experimental temperature, carbon dioxide gas was used to displace the formation crude oil in the core sample at a preset constant pressure, and residual oil saturation was established. After displacement reached an optimal 1.2 PV, ensuring no oil was discharged from the end of the core sample, the gas flow rate, the amount of oil discharged by the gas-driven oil, the amount of water discharged by the gas-driven oil, and the pressure difference between the two ends of the core sample were recorded. The absolute permeability of the gas phase under residual oil saturation conditions was calculated. The formulas for calculating residual oil saturation and absolute permeability of the gas phase are as follows:

[0054]

[0055] In the formula, Residual oil saturation, This refers to the water displacement of gas-driven oil. This refers to the amount of oil discharged during gas-driven oil production. The absolute permeability of the gas phase. The flow rate of the oil phase. Atmospheric pressure, For the viscosity of the gas, and These represent the pressures at both ends of the core sample; The oil displacement efficiency is calculated based on the oil discharge rate and the pore volume of the core sample. The formula for calculating the oil displacement efficiency is as follows:

[0056] In the formula, For oil displacement efficiency; The water saturation and oil saturation saturations for gas-driven oil production are calculated using the water saturation and oil saturation determination models, respectively. The gas saturation ...

[0057] In the formula, For gas saturation, This refers to the oil saturation level during gas-driven oil production. The water saturation level during gas-driven oil production; Based on the calculated oil displacement efficiency, and the oil saturation, water saturation, and gas saturation during gas-driven oil displacement, the relationship between oil displacement efficiency and the three-phase saturation distribution is analyzed and determined.

[0058] As described above, compared with conventional oil displacement efficiency experiments, the experimental method in this embodiment can more clearly identify the fluid seepage state, the proportion of fluid in the core pores, and the distribution law of fluid saturation over time during the core displacement process.

[0059] Furthermore, it also includes measuring the relative permeability of the three phases at different saturation levels: At the experimental temperature, carbon dioxide gas was used to continuously displace the core sample at a preset constant pressure, and formation crude oil and formation water were injected into the core sample at a preset ratio to establish a three-phase seepage steady state inside the core sample. The effective permeability of each phase in three-phase flow is calculated using the formulas for calculating the absolute permeability of each phase. The corresponding relative permeability is then calculated based on the effective and absolute permeability of each phase. The formula for calculating the relative permeability is as follows:

[0060] In the formula, The relative permeability of a single phase. For single-phase effective permeability, This represents the absolute permeability of a single phase. Adjust the injection ratio of formation crude oil and formation water (e.g., 1:1, 1:2, or 3:2), and record the resistivity and nuclear magnetic resonance signal changes of core samples at different injection ratios. Calculate the water saturation and oil saturation during three-phase flow using the water saturation calculation model and the oil saturation calculation model, respectively. Calculate the gas saturation during three-phase flow using the gas saturation calculation formula. Based on the calculated absolute permeability and saturation of the three phases, the relationship between the absolute permeability and saturation distribution of the three phases was analyzed and determined, and three-phase isopermeability diagrams for different injection ratios of formation crude oil and formation water were drawn (reference). Figure 5 ).

[0061] The experimental method of this invention conducts core displacement experiments simulating oil and gas reservoir conditions using a steady-state method. It innovatively applies nuclear magnetic resonance (NMR) and rock resistivity techniques to determine the three-phase saturation of core samples. The abundance of oil content in the core pores is reflected by testing the content of hydrogen nuclei in the oil phase, and this is visually reflected in the form of NMR T2 spectra. The peak area of ​​the T2 spectrum quantitatively reflects the crude oil saturation. Rock resistivity techniques, based on the electrical properties of rocks, determine the water saturation of the core. The experimental method, the calculation process of the three-phase relative permeability and oil displacement efficiency are optimized to determine the saturation distribution of the oil, gas, and water three-phase relative permeability and oil displacement efficiency, thus better simulating the three-phase seepage state under real abandoned oil reservoir conditions and enabling real-time monitoring of the three-phase saturation.

[0062] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Those skilled in the art can modify the technical solutions described in the above embodiments, or make equivalent substitutions for some of the technical features; and all such modifications and substitutions should fall within the protection scope of the appended claims of the present invention.

Claims

1. A reservoir phase permeameter and oil displacement test apparatus, characterized by, The oil reservoir phase permeability and oil displacement testing device comprises: a clamping testing module comprising a resistivity core holder, and a resistivity tester and a nuclear magnetic resonance instrument connected with the resistivity core holder; a displacement module comprising a multi-way valve connected with an input port of the resistivity core holder, and a water phase displacement unit, an oil phase displacement unit and a gas phase displacement unit connected with the multi-way valve respectively, wherein an inlet pressure sensor is arranged on a connection route of the resistivity core holder and the multi-way valve; a metering module comprising an oil-gas-water separator connected with an output port of the resistivity core holder, and a gas metering unit, an oil phase metering unit and a water phase metering unit connected with the oil-gas-water separator respectively, wherein an outlet pressure sensor is arranged on a connection route of the resistivity core holder and the oil-gas-water separator; a terminal processing module connected with the resistivity tester, used for measuring water saturation and resistivity signal value of the core when water displacement is performed, and calibrating a relationship curve of water saturation and resistivity, and connected with the nuclear magnetic resonance instrument, used for measuring oil saturation and nuclear magnetic signal of the core when oil displacement is performed, and calibrating a relationship curve of oil saturation and nuclear magnetic signal.

2. The reservoir phase permeameter and flooding test apparatus of claim 1, wherein: The oil reservoir phase permeability and oil displacement testing device further comprises a back pressure module and a formation simulation module, the back pressure module comprises a back pressure pump connected with an output port of the resistivity core holder, and a back pressure valve arranged on a connection route of the back pressure pump and the resistivity core holder, wherein the back pressure valve is located on a connection route of the outlet pressure sensor and the oil-gas-water separator; the formation simulation module comprises a temperature box, a temperature controller and a convection pump, the resistivity core holder is arranged in the temperature box, the temperature controller is connected with the temperature box, and the convection pump is connected with an input port of the resistivity core holder.

3. The reservoir phase permeameter and flooding test apparatus of claim 1, wherein: The water phase displacement unit comprises a water phase liquid bottle, a water phase displacement pump and a water phase intermediate container connected in sequence, the water phase intermediate container is connected with the multi-way valve, and a water phase pressure sensor is arranged on a connection route of the water phase intermediate container and the multi-way valve; The oil phase displacement unit comprises an oil phase liquid bottle, an oil phase displacement pump and an oil phase intermediate container connected in sequence, the oil phase intermediate container is connected with the multi-way valve, and an oil phase pressure sensor is arranged on a connection route of the oil phase intermediate container and the multi-way valve; The gas phase displacement unit comprises a gas phase liquid bottle, a gas phase displacement pump and a gas phase intermediate container connected in sequence, the gas phase intermediate container is connected with the multi-way valve, and a gas phase pressure sensor is arranged on a connection route of the gas phase intermediate container and the multi-way valve.

4. The oil reservoir phase permeameter and oil displacement test device of claim 1, wherein: The oil phase metering unit comprises an oil phase collection container and an oil phase electronic balance arranged at a bottom of the oil phase collection container, and the water phase metering unit comprises a water phase collection container and a water phase electronic balance arranged at a bottom of the water phase collection container.

5. An experimental method characterized by, The oil reservoir phase permeability and oil displacement testing device is used for testing experiments, and the experimental method comprises: Obtaining a core rock sample of a target oilfield, determining basic parameters of the core rock sample, and performing a formation water saturation treatment on the core rock sample; Performing a water drive experiment on the core rock sample at an experimental temperature, determining the absolute permeability of the water phase after the water drive is stabilized, recording the flow rate change of the water phase and the resistivity change of the core rock sample, and establishing a water saturation calculation model associated with the resistivity; Performing an oil drive water drive experiment on the core rock sample at an experimental temperature, determining the absolute permeability of the oil phase under the condition of irreducible water saturation after the oil drive is stabilized, recording the flow rate change of the oil phase and the nuclear magnetic signal change of the core rock sample, and establishing an oil saturation calculation model associated with the nuclear magnetic signal; Performing a gas drive oil drive experiment on the core rock sample at an experimental temperature, determining the absolute permeability of the gas phase under the condition of residual oil saturation after the gas drive is stabilized, recording the oil displacement of the gas drive oil to determine the oil displacement efficiency, and determining the distribution of three-phase saturation during the gas drive oil according to the water saturation calculation model and the oil saturation calculation model; Performing a three-phase seepage experiment on the core rock sample at an experimental temperature, determining the effective permeability of the three phases after the three-phase seepage is stabilized, and calculating the relative permeability of the three phases according to the determined effective permeability and absolute permeability of the three phases, recording the resistivity change and nuclear magnetic signal change of the core rock sample during the three-phase seepage, and determining the relative permeability of the three phases under different saturations.

6. The experimental method of claim 5, wherein, The method for determining the basic parameters of the core rock sample and performing a formation water saturation treatment on the core rock sample comprises: Preprocessing the obtained core rock sample by sequentially cleaning and drying, and determining the length, cross-sectional area, and outer volume of the core rock sample after preprocessing; Drying the preprocessed core rock sample, recording the dry weight of the core rock sample after drying, vacuumizing the core rock sample after drying, and recording the wet weight of the core rock sample after alcohol saturation, determining the pore volume and porosity of the core rock sample according to the recorded dry weight and wet weight, and the calculation formula of the pore volume and porosity is: wherein is the pore volume of the core sample, is the wet weight, is the dry weight, is the density of the alcohol, is the porosity of the core sample, is the outer surface volume of the core sample; Sequentially drying and vacuumizing the alcohol-saturated core rock sample, and configuring formation water containing deuterium water and mineral salt, and saturating the vacuumized core rock sample with a preset amount of formation water.

7. The experimental method of claim 6, wherein, The method for determining the absolute permeability of the water phase and establishing a water saturation calculation model comprises: At an experimental temperature, using the configured formation water to displace the core rock sample saturated with a preset amount of formation water at a preset displacement constant speed, recording the flow rate of the water phase and the pressure difference between the two ends of the core rock sample after the flow rate of the water phase at the end of the core rock sample is stabilized, and calculating the absolute permeability of the water phase, and the calculation formula of the absolute permeability of the water phase is: wherein is the absolute permeability of the water phase, is the flow rate of the water phase, is the viscosity of the water, is the length of the core sample, is the cross-sectional area of the core sample, is the differential pressure across the core sample; Recording the flow rate change of the water phase and the resistivity change of the core rock sample during the water drive, and establishing a water saturation calculation model associated with the resistivity, and the expression of the water saturation calculation model is: wherein, is the water saturation, is the resistivity of the formation water, is the measured resistivity of the core sample, and is the resistivity correction factor.

8. The experimental method of claim 7, wherein, The method for determining the absolute permeability of the oil phase under the condition of irreducible water saturation and establishing an oil saturation calculation model comprises: At the experimental temperature, formation crude oil is used to displace formation water in the core sample at a preset displacement rate to establish irreducible water saturation. After no water is discharged from the end of the core sample, the oil phase flow rate and the pressure difference between the two ends of the core sample are recorded, and the absolute permeability of the oil phase under the condition of irreducible water saturation is calculated. The absolute permeability of the oil phase under the condition of irreducible water saturation and the absolute permeability of the oil phase are calculated according to the following formula: wherein is the irreducible water saturation, is the water displacement by oil, is the absolute permeability of the oil phase, is the flow rate of the oil phase, is the viscosity of the oil; The change of the oil phase flow rate and the change of the nuclear magnetic signal of the core sample during oil displacement are recorded, and an oil saturation and nuclear magnetic signal correlation oil saturation calculation model is established. The expression of the oil saturation calculation model is: wherein is the oil saturation, is the measured NMR signal intensity of the core sample, is the measured NMR relaxation time of the core sample, is the time interval of the NMR, is the NMR signal intensity of the core sample when the oil phase is completely saturated, is the NMR relaxation time of the core sample when the oil phase is completely saturated.

9. The experimental method of claim 8, wherein, It also includes a method for determining the absolute permeability of the gas phase under the condition of residual oil saturation and determining the three-phase saturation distribution during gas displacement of oil: At the experimental temperature, carbon dioxide gas is used to displace formation crude oil in the core sample at a preset constant pressure to establish residual oil saturation. After no oil is discharged from the end of the core sample, the gas phase flow rate, the oil displacement amount, the water displacement amount, and the pressure difference between the two ends of the core sample are recorded, and the absolute permeability of the gas phase under the condition of residual oil saturation is calculated. The residual oil saturation and the absolute permeability of the gas phase are calculated according to the following formula: wherein, Sro is the residual oil saturation, Wd is the drainage of gas-drive oil, Wod is the oil displacement of gas-drive oil, Kg is the absolute permeability of the gas phase, Fh is the flow of the oil phase, P is the atmospheric pressure, μg is the viscosity of the gas, and P1 and P2 are the pressures at the ends of the core sample, respectively; The oil displacement efficiency is calculated according to the oil displacement amount and the pore volume of the core sample. The calculation formula of the oil displacement efficiency is: In the formula, Oil displacement efficiency; The water saturation and the oil saturation during gas displacement of oil are calculated according to the water saturation calculation model and the oil saturation calculation model, respectively, and the gas saturation during gas displacement of oil is calculated according to the water saturation and the oil saturation during gas displacement of oil. The calculation formula of the gas saturation is: wherein Sogas is the gas saturation, Sooil is the oil saturation when gas is displacing oil, Sowater is the water saturation when gas is displacing oil; According to the calculated oil displacement efficiency, and the oil saturation, water saturation, and gas saturation during gas displacement of oil, the relationship between the oil displacement efficiency and the three-phase saturation distribution is analyzed and determined.

10. The experimental method of claim 9, wherein, It also includes measuring the relative permeability of the three phases under different saturations: At the experimental temperature, carbon dioxide gas is used to continuously displace the core sample at a preset constant pressure, and formation crude oil and formation water are simultaneously injected into the core sample at a preset ratio to establish a steady state of three-phase seepage in the core sample. According to the absolute permeability calculation formula of each phase, the effective permeability of each phase during three-phase seepage is calculated, and the corresponding relative permeability is calculated according to the effective permeability and the absolute permeability of each phase. The calculation formula of the relative permeability is: wherein the relative permeability for a single phase, the effective permeability for a single phase, the absolute permeability for a single phase; The injection ratio of formation crude oil and formation water is adjusted, and the resistivity change and the nuclear magnetic signal change of the core sample at different injection ratios are recorded. The water saturation and the oil saturation during three-phase seepage are calculated according to the water saturation calculation model and the oil saturation calculation model, respectively, and the gas saturation during three-phase seepage is calculated according to the calculation formula of the gas saturation. According to the calculated three-phase relative permeability and three-phase saturation, the relationship between the three-phase relative permeability and the three-phase saturation distribution is analyzed and determined, and the three-phase isoperimetric graph of formation crude oil and formation water at different injection ratios is drawn.

Images