An experimental design method for measuring the phase permeability hysteresis parameters by gas-water alternation in high-temperature and high-pressure oil-bearing rock cores

Abstract

The present invention relates to the field of oil and gas development, and particularly to an experimental design method for measuring the phase permeability hysteresis parameters of high-temperature and high-pressure oil-bearing core samples by gas-water alternation. The purpose of the present invention is to calculate the hysteresis parameters in the relative permeability hysteresis model through a specifically designed relative permeability experiment, directly calculate the hysteresis parameters such as gas-water relative permeability, gas-oil relative permeability, and oil-water relative permeability required for relative permeability hysteresis numerical simulation from the relative permeability experiment results, improve the accuracy of parameter acquisition, avoid the large amount of fitting and adjustment processes in the existing methods, provide a rapid research tool for evaluating research such as CO2 sequestration, underground gas storage construction, gas-water alternation enhanced oil recovery, and hydrogen storage that are affected by relative permeability hysteresis, and reduce the numerical simulation workload.

Description

Technical Field

[0001] The present invention relates to the field of oil and gas development, and particularly to a method for determining hysteresis parameters in a relative permeability hysteresis model through relative permeability experiments. Technical Background

[0002] The relative permeability hysteresis effect has a non-negligible impact on applications such as enhanced oil recovery by gas injection, construction of gas storage reservoirs, and CO 2 sequestration, etc. The existing methods for determining relative permeability hysteresis parameters in numerical simulation studies are mainly based on fitting experiments. For example, "Analysis Method, Equipment and Storage Medium for Injection-Production Relative Permeability Hysteresis in Fractured-Vuggy Gas Storage Reservoirs" (CN117993228A) proposes to consider the relative permeability hysteresis effect in the numerical simulation study of gas storage reservoirs, but only performs calculations on gas storage reservoirs in the existing relative permeability hysteresis model, without considering the representativeness of the input relative permeability hysteresis parameters in the model and their acquisition methods.

[0003] At present, the experimental research on gas-water alternating relative permeability has become mature. There are already multiple two-phase and three-phase relative permeability hysteresis models at home and abroad, and some models have been applied to commercial simulators. However, the acquisition of key parameters in the relative permeability hysteresis model is based on numerical simulation fitting, and there is no simple calculation method directly based on experimental results. Therefore, the present invention specifically designs a multi-cycle gas-water mutual displacement experiment for oil-bearing cores under high temperature and high pressure, and establishes a calculation method for the input parameters of the three-phase relative permeability hysteresis model during the gas-water alternation process, improving the accuracy of parameter acquisition and reducing the workload of numerical simulation fitting. Summary of the Invention

[0004] The present invention aims to provide a method for calculating hysteresis parameters in a relative permeability hysteresis model through a specifically designed relative permeability experiment, directly calculating the hysteresis parameters required for relative permeability numerical simulation from the relative permeability experiment results, which can improve the accuracy of parameter acquisition and avoid the large amount of fitting and adjustment processes in the existing methods. It provides a rapid research tool for evaluating research such as CO 2 sequestration, underground gas storage reservoir construction, enhanced oil recovery by gas-water alternation, hydrogen storage, etc., and reduces the workload of numerical simulation.

[0005] To achieve the above invention purpose, the present invention provides the following technical solutions:

[0006] An experimental design method for measuring relative permeability hysteresis parameters by gas-water alternation of an oil-bearing core under high temperature and high pressure, comprising the following steps:

[0007] Step S1: Conduct a multi-cycle CO 2 -water alternating mutual displacement experiment using actual reservoir cores and measure the relative permeability data of the cores;

[0008] Step S2: Determine the calculation method for relative permeability hysteresis model hysteresis parameters, and the calculation is divided into non-wetting phase relative permeability, wetting phase relative permeability, and intermediate wetting phase relative permeability;

[0009] Step S3: Select data from the multi - cycle relative permeability curve data measured in the experiment and calculate the hysteresis parameters a and α of the hysteresis model respectively:

[0010] Step S4: Complete the PVT fitting of the crude oil according to the crude oil and degassed composition data in combination with the saturation pressure, gas - oil ratio, and MMP experimental data;

[0011] Step S5: Establish a core model in the simulator based on the experimental core physical data, and input the hysteresis parameters to activate the hysteresis effect function of the simulator;

[0012] Step S6: Output the comparison experiment of the model recovery rate to verify the fitting effect.

[0013] As a preferred embodiment of the present invention, in step S1, the gas - water two - phase relative permeability curve, water - oil three - phase relative permeability curve, and gas - oil three - phase relative permeability curve are measured respectively. Among them, the gas - water two - phase relative permeability experiment is directly carried out for displacement measurement after the core is saturated with water. The oil - containing three - phase relative permeability experiment is to establish irreducible water by displacing with live oil after the core is saturated with water, and then carry out gas drive and water drive to establish residual oil. Considering the influence of the start of gas drive and the start of water drive on the relative permeability hysteresis phenomenon, if the residual oil is established by the start of gas drive, then the gas - water alternating experiment with the start of six - cycle water drive is carried out subsequently, and vice versa; through the three types of relative permeability experiments, the gas - water two - phase relative permeability curve, gas - oil and water - oil three - phase relative permeability curve of the reservoir core required for subsequent calculations and their multi - cycle curve changes are obtained.

[0014] As a preferred embodiment of the present invention, the calculation of the non - wetting phase relative permeability in step S2 includes the following sub - steps:

[0015] (a) Calculate the drainage process gas - saturation scanning curve

[0016]

[0017] Where: n---represents the number of cycles; taking n = 2 as an example, ---The relative permeability at the gas - saturation Sg in the second drainage curve; ---The relative permeability at Sg in the first drainage; ---The relative permeability of the gas - saturation at the starting point of the second drainage curve in the first drainage curve; ---The water - saturation at the end of the second drainage; ---The water - saturation at the starting point of the second drainage curve; S g ---The gas - saturation in the second drainage curve; ---The gas - saturation at the starting point of the second drainage curve; ---The relative permeability at the gas - saturation at the starting point of the second drainage curve in the first imbibition curve;

[0018] (b) Calculate the imbibition process gas saturation scanning curve

[0019]

[0020] Wherein:

[0021] Among them: --- Gas saturation at the conversion of the nth cycle; (S g ) n --- Gas saturation of the nth cycle; --- Gas saturation at the end of the (n - 1 cycle; (S gi ) n --- Initial gas saturation of the nth cycle; --- Residual gas saturation at the conversion of the nth cycle; (S gr ) n --- Residual gas saturation of the nth cycle.

[0022] As a preferred embodiment of the present invention, calculating the wetting phase relative permeability in step S2 includes the following sub-steps:

[0023] (a) Calculate the imbibition process water saturation scanning curve

[0024]

[0025] Among them: --- Input water phase relative permeability of the first imbibition process; --- Input water phase relative permeability of the second imbibition process; --- Initial gas saturation; (S g ) max --- Maximum gas saturation;

[0026] (b) Calculate the displacement process water saturation scanning curve

[0027] 1) If

[0028]

[0029] 2) If

[0030]

[0031] 3) If the gas saturation is constant

[0032]

[0033] Wherein: --- The relative permeability of the water phase at the end of the final imbibition;

[0034] As a preferred embodiment of the present invention, calculating the relative permeability of the intermediate wetting phase in step S2 includes the following sub-steps:

[0035] In the relative permeability hysteresis model, the relative permeability of the oil phase is a function of the oil saturation and the historical saturation, and thus the relative permeability of the intermediate wetting phase can be calculated;

[0036] S or =(S or ) sgt = 0 -aS gt (11)

[0037] Wherein: Sg t ---- The trapped gas saturation after water flooding;

[0038] Calculate the Land coefficient of the trapped gas:

[0039]

[0040] Wherein: S gi --- The initial gas saturation, S gr --- The trapped gas saturation;

[0041] The hysteresis parameters input in the simulator are "a" and "α". After enabling the hysteresis function in the simulator, the change in the trapped gas saturation in multi-cycle experiments is represented by inputting the Land coefficient. The hysteresis parameters are calculated by formulas (1) and (11), and the trapped gas coefficient is calculated by formula (12).

[0042] Wherein:

[0043] "a" represents the degree of reduction of the relative permeability of the oil phase by the residual oil saturation during the simulation of the WAG process;

[0044] "α" is used to calculate the input parameter of the scanning curve during the displacement (i.e., increasing the gas saturation) process, representing the degree of reduction of the relative permeability with the change in gas saturation;

[0045] "C" represents the change coefficient of the trapped gas saturation in different cycles.

[0046] As a preferred embodiment of the present invention, step S3 further includes the following sub-steps:

[0047] Step S31: Calculation of the hysteresis parameter "a": According to the relative permeability data of the experimental results, the residual oil saturation in each cycle of the six cycles at the start of gas flooding and the start of water flooding, as well as the trapped gas saturation at the end of water flooding, are respectively counted and substituted into formula (11) for calculating the hysteresis parameter "a";

[0048] Step 32: Calculation of the hysteresis parameter "α": Calculating the parameter "α" requires the relative permeability data of adjacent cycles in six-cycle experiments. Determine the other parameters in formula (1) and substitute them into the drainage curve and imbibition curve of adjacent cycles to calculate the hysteresis parameter "α".

[0049] Step 33: Calculation of the trapped gas Land coefficient "C": According to the saturation data of the experimental results, respectively count the initial gas saturation of each cycle in six cycles at the start of gas drive and water drive, and the trapped gas saturation after the end of displacement, and substitute them into formula (12) to calculate the trapped gas coefficient "C".

[0050] As a preferred solution of the present invention, in step S4, the content of each component in the crude oil should be determined first. By performing chromatographic analysis on dead oil to obtain the composition of each component in the crude oil and natural gas, input the component data into the PVT module of the simulator, perform pseudo-component division on the well stream composition, and then fit the key parameters of crude oil physical properties such as MMP (minimum miscibility pressure), gas-oil ratio, saturation pressure, viscosity, volume coefficient, and relative volume according to the experimental data of crude oil analysis, and ensure that the error between the experimental value and the fitted value is within 5%.

[0051] As a preferred solution of the present invention, in step S5, a core model should be established 1:1 in the simulator according to the experimentally measured core physical data, input the experimentally measured gas-water relative permeability curve, gas-oil relative permeability curve, oil-water relative permeability curve, porosity, and permeability data, import the fluid after completing the PVT fitting, and then input the hysteresis parameters "a" and "α" calculated according to the experimental data to enable the relative permeability hysteresis simulation function of the model, and establish the same experimental conditions and injection parameters in the model for simulation.

[0052] As a preferred solution of the present invention, step S6 further includes: after the model runs, output the model recovery factor result and compare it with the experimental recovery factor result to view the fitting effect. If the error between the final recovery factor of the model and the experimental recovery factor is small, it means that the hysteresis parameters calculated from the experimental data are effective and can be applied to subsequent mechanism model or geological model research. If the error between the model recovery factor and the experimental recovery factor is large, the hysteresis parameters need to be adjusted.

[0053] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0054] (1) The present invention designs a multi-cycle gas-water relative permeability experiment that can directly measure the parameters of the relative permeability hysteresis model.

[0055] (2) Through the designed targeted experiment, directly calculate the input parameters of the relative permeability hysteresis model, including in the first cycle, gas-water relative permeability, gas-oil relative permeability, oil-water relative permeability, a, α, C.

[0056] (3) The relative permeability curves obtained from experiments are used as direct input parameters for the model. The model parameters calculated based on the experimental relative permeability can be directly input for model verification, directly used for subsequent simulations, or used as the initial values for fitting and adjustment, which improves the accuracy of parameter acquisition and avoids the large number of fitting and adjustment processes in existing methods. Description of the Drawings

[0057] Figure 1 High-temperature and high-pressure CO 2 - Flow chart of the relative permeability hysteresis experiment for water-alternating gas flooding;

[0058] Figure 2 Flow chart of the implementation method;

[0059] Figure 3 Two-phase relative permeability curve diagram of the experimental results;

[0060] Figure 4 Three-phase relative permeability curve diagram of the experimental results;

[0061] Figure 5 Three-phase relative permeability saturation path diagram of the experimental results;

[0062] Figure 6 Calculation result diagram of the hysteresis parameter a;

[0063] Figure 7 Specific position of the calculation parameter of the starting hysteresis parameter α for gas flooding in the experimental relative permeability curve;

[0064] Figure 8 Specific position of the calculation parameter of the starting hysteresis parameter α for water flooding in the experimental relative permeability curve;

[0065] Figure 9 Calculation result diagram of the trapped gas Land coefficient C;

[0066] Figure 10 Core model diagram with a grid number of 29×3×3 established;

[0067] Figure 11 Fitting result diagram of the model recovery factor and the experimental recovery factor; Detailed Implementation Manner

[0068] In order to more clearly describe the invention purpose, technical solution, and technical effect advantages in the specific implementation cases of the present invention, the following will describe the solutions in the specific embodiments in detail in conjunction with the specification drawings of the present invention. The specific technical solutions involved in the following specific embodiments are only for clearly and completely describing the innovative technical solutions of the present invention. They are only a part of the specific implementation schemes that the present invention can adopt, not all the embodiments, and should not be construed as a limitation to the innovative solutions of the present invention. Any solutions adopting the same inventive concept of the present invention should be included in the protection scope of the present invention.

[0069] Secondly, the relevant descriptions of the drawings in the specific embodiments of the present invention are only for the convenience of those skilled in the art to understand the solution of the present invention. The partial details shown in the drawings are for the convenience of clearly presenting the technical solution, and it should not be considered that all the technical features in the drawings must be incorporated into the specific embodiments. Moreover, the detailed features in the drawings should not be regarded as additional limitations on the innovative technical solution of the present invention. The components in each embodiment described and shown in the drawings can be combined and arranged in different configurations, and these changes in combination and arrangement should be regarded as a part of all the embodiments of the innovative solution of the present invention and fall within the scope of protection of the present invention.

[0070] In summary, the solutions or descriptions presented in the specific embodiments and drawings of the present invention are not intended to limit the scope of protection claimed, but merely represent selected embodiments / cases to assist those skilled in the art in understanding the relevant innovative solutions. Based on these embodiments, all other equivalent or parallel embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection claimed by the present invention.

[0071] In addition, in the description of the embodiments of the present invention, "several", "multiple", and "a number of" represent at least 2. It can be any situation such as 3, 4, 5, 6, 7, 8, 9, etc., and even more than 9.

[0072] An experimental design method for measuring the phase permeability hysteresis parameters of high-temperature and high-pressure oil-bearing rock cores by gas-water alternation includes the following steps:

[0073] (1) Conduct high-temperature and high-pressure multi-cycle CO 2 -water alternating mutual displacement experiments on actual reservoir cores and measure the phase permeability data of the cores;

[0074] The implementation process is as Figure 1 shown. Before the experiment, measure the size, porosity, permeability, and irreducible water saturation data of the experimental core to provide accurate data for establishing the core model. The specific parameters of the experimental core are shown in Table 1 as follows:

[0075] Table 1

[0076] Length, cm Average diameter, cm Pore volume, cm3 Core volume, cm3 Permeability, md Irreducible water saturation Average porosity 28.87 2.49 31.96 140.88 215.69 0.35 0.23

[0077] The relative permeability curves were measured through mutual displacement experiments, mainly referring to the national standard: "GB / T 28912-2012 Determination Method for Relative Permeability of Two-Phase Fluids in Rock" and the invention patent "Method for Determining Gas-Water Relative Permeability Curve at High Temperature and High Pressure in Formation" (CN103645126B, September 30, 2015). The tests of the relative permeability of three-phase fluids in oil-bearing cores with multi-cycle gas-water mutual displacement and the relative permeability of gas-water two-phase were carried out. The two-phase experiment and the three-phase experiment were each measured for six cycles. Considering the influence of the start of gas drive and the start of water drive in the oil-bearing core during the three-phase experiment, the three-phase relative permeability experiment was divided into two categories, namely the start of gas drive and the start of water drive. The specific experimental process is as Figure 2 shown.

[0078] The experimental steps in this embodiment are as follows:

[0079] (a) Prepare equilibrium gas and equilibrium water

[0080] ① Prepare formation water according to the formation water analysis data of the actual oil reservoir.

[0081] ② Select pure CO 2 , at the experimental temperature and pressure, fill the intermediate containers for water samples and gas samples with the prepared formation water and high-pressure CO 2 at the experimental pressure respectively. Load the sample dispenser with 50% by volume of formation water and inject 50% of CO 2 to the experimental pressure, and shake and stir for 8-10 hours, keeping an excess of CO 2 dissolved in water at the experimental temperature and pressure.

[0082] ③ Refer to the standard SY / T5543-2002 "Analysis Method for Physical Properties of Condensate Gas Reservoir Fluids", conduct single-stage separation tests on the equilibrium gas and equilibrium formation water. Transfer the equilibrium gas sample in the upper part and the equilibrium water sample in the lower part of the sample dispenser into the PVT instrument to measure the volume factor B g of the equilibrium gas and the volume factor B w of the equilibrium formation water and the gas-water ratio.

[0083] The volume factors of the finally prepared equilibrium gas and equilibrium water are shown in Table 2:

[0084] Table 2

[0085]

[0086] (b) Saturated water: Dry the core and weigh it, evacuate it, saturate the core at room temperature and 6000 psi, take it out and weigh it again after 24 - 36 hours to determine the saturated water volume of the core. Load the core into the core holder, and then into the high-pressure long core holder. Close the outlet and pressurize it to the experimental pressure of 32.67 MPa with formation water, and heat it to 64 °C at the same time. During the pressurization process, keep the confining pressure 3 - 4 MPa higher than the inlet pressure. Wait until the temperature and pressure are stable. At the experimental temperature and pressure, conduct constant-pressure equilibrium water displacement of the formation water until stable to complete the core saturation with water.

[0087] Two-phase experiment: After the experimental core is saturated with water, directly start gas drive to measure the gas-water two-phase relative permeability.

[0088] Three-phase experiment: After the experimental core is saturated with water, use the prepared live oil to carry out oil displacement to establish irreducible water, and then conduct constant-pressure equilibrium water drive to establish residual oil (start with gas drive to establish residual oil at the beginning of water drive). Finally, measure the gas-oil and water-oil three-phase relative permeability.

[0089] (c) Gas drive water (the measurement process of two-phase and three-phase relative permeability is the same): Use the constant-pressure gas drive method to test the gas-water relative permeability. The experimental process and records are consistent with the standard, including time, cumulative water production (including condensed water), cumulative gas production, confining pressure, inlet and outlet pressures. Drive until no water comes out, and then record the gas output per unit time to determine the gas permeability under irreducible water conditions.

[0090] (d) Water drive gas (the measurement process of two-phase and three-phase relative permeability is the same): Use the constant-pressure water drive method to test the water-gas relative permeability. The experimental process and records are consistent with the standard, including time, cumulative water production (including condensed water), cumulative gas production, confining pressure, inlet and outlet pressures, until no gas comes out after water drive. Then record the water output per unit time to determine the water permeability under trapped gas conditions.

[0091] Final experimental results Figure 3 、 4 As shown, they are respectively the six-cycle two-phase relative permeability curves and three-phase relative permeability curves at the start of gas drive and water drive, Figure 5 which represent the saturation path diagrams at the start of gas drive and water drive in the three-phase relative permeability experiment.

[0092] (2) Select data according to the multi-cycle relative permeability curve data measured in the experiment and calculate the hysteresis parameters a and α in the relative permeability hysteresis model respectively;

[0093] (a) Calculation of hysteresis parameter "a":

[0094] According to the experimental relative permeability data, the residual oil saturation at the start of gas flooding and water flooding in each of the six cycles and the trapped gas saturation at the end of water flooding were respectively counted and substituted into formula (11) to fit the slope to obtain the hysteresis parameter "a". The trapped gas saturation and residual oil saturation data for the six experimental cycles are shown in Table 3 below:

[0095] Table 3

[0096] Cycle Sgt, %(gas start) Sor, %(gas start) Sgt, %(water start) Sor, %(water start) 1 4.81 34.67 7.41 33.88 2 14.64 26.00 15.09 28.25 3 18.63 23.19 15.93 28.25 4 18.90 23.19 16.54 28.25 5 19.19 23.19 16.81 28.25 6 19.50 23.19 16.95 28.25

[0097] Since the residual oil saturation no longer changes starting from the fourth cycle, to reduce the calculation error, the data of the first three cycles were selected and substituted into the formula for fitting calculation. The calculation results are as Figure 6 shown. The slope in the figure is the hysteresis parameter "a".

[0098] According to the final experimental data results: "a" at the start of gas flooding = 0.84, "a" at the start of water flooding = 0.688.

[0099] (b) Calculation of the hysteresis parameter "α":

[0100] Different from the calculation method of parameter "a", the calculation of parameter "α" requires the relative permeability data of adjacent experimental cycles. According to the experimental data and substituting into formula (1), the other parameters can be used to calculate the hysteresis parameter "α". Taking n = 2 as an example, the other formula parameters for calculating the hysteresis parameter "α" at the start of gas flooding in formula (1) can be determined from the drainage curve and imbibition curve of the first and second cycles (as Figure 7 shown), and the start of water flooding is as Figure 8 shown.

[0101] According to the final experimental data calculation results: "α" at the start of gas flooding = 2.31, "α" at the start of water flooding = 0.536.

[0102] (c) Calculation of the trapped gas Land coefficient "C":

[0103] The initial gas saturation in each cycle and the trapped gas saturation after the end of gas flooding in the six cycles at the start of gas flooding and water flooding were counted from the experimental data, as shown in Table 4 below:

[0104] Table 4

[0105] Cycle Sgi (gas start), % Sgr (gas start), % Sgi (water start), % Sgr (water start), % 1 3.04 41.87 2.01 39.91 2 13.36 46.57 6.07 47.52 3 16.64 45.46 16.31 49.58 4 16.77 46.03 17.50 50.67 5 16.81 46.64 17.67 51.57 6 16.91 47.41 17.81 52.09

[0106] The data was sorted out and substituted into formula (12) for fitting calculation. The calculation results are as Figure 9 shown.

[0107] According to the final experimental data calculation results: "C" at the start of gas flooding = 2.1, "C" at the start of water flooding = 1.89.

[0108] (3) Complete the crude oil PVT fitting based on the crude oil and degassed composition data in combination with experimental data such as saturation pressure, gas-oil ratio, MMP, etc.;

[0109] Obtain the component data through chromatographic analysis, input the data into the PVT fitting module of the simulator, and fit the key parameters of MMP (minimum miscibility pressure), gas-oil ratio, saturation pressure, viscosity, volume coefficient, and relative volume. According to the data in the crude oil analysis experimental report, the experimental value of crude oil MMP is 27.67 MPa, and the fitted value is 27.50 MPa. The experimentally measured viscosity of crude oil is 5.994 cP, and the fitted value is 5.754 cP. The experimental gas-oil ratio is 23.8 m 3 / m 3 , and the fitted gas-oil ratio is 23.68 m 3 / m 3 , the experimental saturation pressure is 5.09 MPa, the fitted value is 5.14 MPa, the experimental volume coefficient is 1.0816, and the fitted volume coefficient is 1.0814. The error of all fitting items is within 5%, meeting the fitting requirements.

[0110] (4) Establish a core model in the simulator based on the experimental core physical data, and input the hysteresis parameter to activate the hysteresis effect function of the simulator;

[0111] Establish a core model with the same size and a grid number of 29×3×3 in the simulator according to the experimentally measured core physical data (as Figure 10 shown), input the experimentally measured gas-water two-phase relative permeability curve and gas-oil three-phase relative permeability curve in the model. The porosity of the model is 0.23, the permeability is 215.69 md, and the irreducible water saturation is 0.35. After importing the fluid with completed PVT fitting, input the calculated hysteresis parameter to turn on the relative permeability hysteresis simulation function of the model, and establish the same conditions and injection parameters as in the experiment in the model for simulation.

[0112] (5) Output the comparison experiment of the model recovery factor to verify the fitting effect.

[0113] After completing the model operation, output the model recovery factor result, and compare it with the experimental recovery factor result to view the fitting effect (as Figure 11 ). From the fitting result of the recovery factor, the difference between the experimental recovery factor and the model recovery factor at the start of gas drive and water drive is small, indicating that the fitting effect of the core model is good. The hysteresis parameter calculated through the experiment has high accuracy and reliability, and can be directly applied to the subsequent research on the relative permeability hysteresis effect of the mechanism model and geological model.

[0114] The above are only embodiments of the present invention, and common general technical solutions and / or features in the solutions are not described in detail herein. It should be noted that for those skilled in the art, without departing from the technical solution of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicability of the patent. The protection scope claimed in this application shall be subject to the content of its claims, and the specific implementation manners described in the specification can be used to interpret the content of the claims.

Claims

1. An experimental design method for measuring phase permeability hysteresis parameters of high-temperature and high-pressure oil-bearing core gas-water alternation, characterized in that: The steps include: Step S1: Conduct high temperature and high pressure multi-cycle CO2-water alternating mutual drive experiments using actual reservoir cores and measure core relative permeability data; Step S2: determining a calculation method for hysteresis parameters of the phase permeability hysteresis model, wherein the calculation is divided into non-wetting phase permeability, wetting phase permeability and intermediate wetting phase permeability; Step S3: Select data based on the experimentally measured multi-cycle phase permeability curve data to calculate the hysteresis model hysteresis parameters a and α: Step S4: completing crude oil PVT fitting based on crude oil and degassing composition data combined with saturation pressure, gas-oil ratio, and MMP experimental data; Step S5: Establish a core model in the simulator according to the experimental core physical data, and input hysteresis parameters to start the simulator hysteresis effect function; Step S6: Output the model recovery factor comparison experiment to verify the fitting effect.

2. The experimental design method for measuring phase permeability hysteresis parameters of high-temperature and high-pressure oil-bearing core gas-water alternating measurements as claimed in claim 1, characterized in that: In the step S1, the gas-water two-phase permeability curve, the water-oil three-phase permeability curve, and the gas-oil three-phase permeability curve are measured respectively, wherein the gas-water two-phase permeability experiment is directly carried out after the core is saturated with water for displacement measurement, and the oil-containing three-phase permeability experiment is to use active oil displacement to establish bound water after the core is saturated with water, and then gas drive and water drive are carried out to establish residual oil. Considering the influence of gas drive start and water drive start on the permeability hysteresis phenomenon, if gas drive is used to start to establish residual oil, a gas-water alternation experiment starting with six cycles of water drive is subsequently carried out, and vice versa; the gas-water two-phase permeability curve and the gas-oil, water-oil three-phase permeability curve of the reservoir core required for subsequent calculations are obtained through three types of permeability experiments, as well as their multi-cycle curve changes.

3. The experimental design method for measuring the phase permeability hysteresis parameters of the high-temperature and high-pressure oil-bearing core gas-water alternating measurement according to claim 1, characterized in that: The calculation of the non-wetting phase permeability in step S2 includes the following sub-steps: (a) Calculation of gas saturation scanning curve during displacement process Where: n---represents the number of cycles; take n=2 as an example, ---Relative permeability at the gas saturation (Sg) in the second drainage curve; ---Relative permeability at the first drainage (Sg); --- Relative permeability of gas saturation at the starting point of the second drainage curve in the first drainage curve; ---Water saturation at the end of the second drainage; ---Water saturation at the starting point of the second drainage curve; Sg---Gas saturation in the second drainage curve; ---Gas saturation at the starting point of the second drainage curve; ---Relative permeability at gas saturation at the starting point of the second drainage curve in the first imbibition curve; (b) Calculation of gas saturation scanning curve during imbibition process Where: in: ---Gas saturation at the time of the nth cycle transition; (S g ) n ---Gas saturation in the nth cycle; --- Gas saturation at the end of the n-1th cycle; (S gi ) n --- Initial gas saturation of the nth cycle; ---Residual gas saturation at the time of the nth cycle conversion; (S gr ) n ---Residual gas saturation in the nth cycle.

4. The experimental design method for measuring phase permeability hysteresis parameters of high-temperature and high-pressure oil-bearing core gas-water alternating measurements as claimed in claim 3, characterized in that: Calculating the wetting phase permeability in step S2 includes the following sub-steps: (a) Calculation of water saturation scanning curve during imbibition process in: ---The first water phase relative permeability input; --- Second water phase relative permeability; --- Initial gas saturation; (S g ) max --- Maximum gas saturation; (b) Calculation of water saturation scanning curve during displacement process 1) If 2) If 3) If the gas saturation is constant in: ---Water phases infiltrate at the end of final imbibition.

5. The experimental design method for measuring the phase permeability hysteresis parameters of the high-temperature and high-pressure oil-bearing core gas-water alternating method according to claim 4, characterized in that: The calculation of the intermediate wetting phase permeability in step S2 includes the following sub-steps: In the phase permeability hysteresis model, the oil phase relative permeability is a function of the oil saturation and the historical saturation, from which the intermediate wetting relative permeability can be calculated; Where: Sgt----trapped gas saturation after water flooding; Calculate the captured gas Land coefficient: Where: Sgi---initial gas saturation, Sgr---trapped gas saturation; The hysteresis parameters input in the simulator are "a" and "α". After the hysteresis function is turned on in the simulator, the Land coefficient is input to represent the change of the captured gas saturation in the multi-cycle experiment. The hysteresis parameters are calculated by formula (1) and formula (11), and the captured gas coefficient is calculated by formula (12). in: "a" represents the reduction degree of residual oil saturation to oil phase relative permeability in the WAG simulation process; "α" is used to calculate the input parameter of the scanning curve during the displacement (i.e., increasing gas saturation), representing the reduction degree of relative permeability with the change of gas saturation; "C" represents the coefficient of variation of captured gas saturation at different periods.

6. The experimental design method for measuring phase permeability hysteresis parameters of high-temperature and high-pressure oil-bearing core gas-water alternating measurements as claimed in claim 5, characterized in that: The step S3 also includes the following sub-steps: Step S31: Calculation of hysteresis parameter "a": According to the experimental results, the residual oil saturation at the start of gas drive and water drive in each of the six cycles and the trapped gas saturation at the end of water drive are respectively calculated and substituted into formula (11) to calculate the hysteresis parameter "a"; Step 32: Calculation of hysteresis parameter "α": To calculate parameter "α", phase permeability data of adjacent cycles in six-cycle experiments are required. Formula (1) and other parameters are substituted into the drainage curve and imbibition curve of adjacent cycles to obtain hysteresis parameter "α". Step 33: Calculation of the trapped gas Land coefficient "C": Based on the saturation data of the experimental results, the initial gas saturation in each of the six cycles at the beginning of gas drive and water drive, as well as the trapped gas saturation after the displacement, are statistically analyzed and substituted into formula (12) to calculate the trapped gas coefficient "C".

7. The experimental design method for measuring phase permeability hysteresis parameters of high-temperature and high-pressure oil-bearing core gas-water alternating measurements as claimed in claim 1, characterized in that: In step S4, the content of each component in the crude oil should be determined first, and the composition of each component in the crude oil and natural gas should be obtained by chromatographic analysis of the dead oil. The component data should be input into the simulator PVT module, and the well flow composition should be divided into pseudo-components. Then, according to the crude oil analysis experimental data, the key parameters of MMP (minimum miscibility pressure), gas-oil ratio, saturation pressure, viscosity, volume coefficient and relative volume crude oil physical properties should be fitted, and it should be ensured that the error between the experimental value and the fitting value is within 5%.

8. The experimental design method for measuring phase permeability hysteresis parameters of high-temperature and high-pressure oil-bearing core gas-water alternating measurements as claimed in claim 1, characterized in that: In step S5, a core model should be established in the simulator at a ratio of 1:1 based on the experimentally measured core physical data, and the experimentally measured gas-water phase permeability curve, gas-oil phase permeability curve, oil-water phase permeability curve, and porosity and permeability data should be input. After the PVT-fitted fluid is imported, the hysteresis parameters "a" and "α" calculated based on the experimental data should be input to start the model phase permeability hysteresis simulation function, and the same experimental conditions and injection parameters should be established in the model for simulation.

9. The experimental design method for measuring phase permeability hysteresis parameters of high-temperature and high-pressure oil-bearing core gas-water alternating measurements as claimed in claim 1, characterized in that: The step S6 also includes: outputting the model recovery result after completing the model operation, and comparing it with the experimental recovery result to check the fitting effect. If the error between the final recovery rate of the model and the experimental recovery rate is not large, it means that the hysteresis parameters calculated by the experimental data are effective and can be applied to subsequent mechanism model or geological model research. If the error between the model recovery rate and the experimental recovery rate is large, the hysteresis parameters need to be adjusted.

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