Method, apparatus, and storage medium for determining state of reservoir fluid interaction

Abstract

Embodiments of the present application provide a method, device and storage medium for determining the state of reservoir fluid interaction, belonging to the field of reservoir exploration and development. The method for determining the state of reservoir fluid interaction comprises: obtaining the current water saturation and the current CO2 displacement pressure of a target reservoir; and determining the current fluid interaction state of the target reservoir according to the current water saturation and the current CO2 displacement pressure based on a predetermined target correspondence relationship among the water saturation, the CO2 displacement pressure and the state of fluid interaction. The present application can improve the accuracy of the classification result of the state of reservoir fluid interaction.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil reservoir exploration and development, and in particular to a method and device for determining the fluid interaction state of an oil reservoir and a storage medium. BACKGROUND

[0002] CO2 is an efficient displacement medium with good displacement performance, which can improve recovery efficiency and achieve carbon sequestration. A large number of studies have been conducted on CO2-EOR technology at home and abroad, and the fluid interaction state of CO2 and crude oil in the oil reservoir has been divided into non-miscible, near-miscible, miscible and completely miscible fluid interaction states. In the prior art, in order to determine the fluid interaction state of the oil reservoir, the technical personnel usually determines the fluid interaction state of CO2 and crude oil in the oil reservoir by using a fine tube experiment, but the above method has a large difference from the actual reservoir environment and fluid, and has the problem of large error. SUMMARY

[0003] The purpose of the embodiments of the present application is to provide a method and device for determining the fluid interaction state of an oil reservoir and a storage medium, so as to solve the problem that the fluid interaction state cannot be judged under different water saturation in the prior art.

[0004] In order to achieve the above-mentioned purpose, the first aspect of the embodiments of the present application provides a method for determining the fluid interaction state of an oil reservoir, which comprises:

[0005] obtaining the current water saturation and the current CO2 displacement pressure of the target oil reservoir;

[0006] determining the current fluid interaction state of the target oil reservoir according to the current water saturation and the current CO2 displacement pressure based on the target correspondence relationship between the water saturation, the CO2 displacement pressure and the fluid interaction state.

[0007] In the embodiments of the present application, the determination of the target correspondence relationship comprises: obtaining a plurality of simulated interfacial tensions and a plurality of simulated oil displacement efficiencies according to a plurality of first preset CO2 displacement pressures and a plurality of preset water saturation degrees based on a pre-constructed CO2-oil-water three-phase reservoir numerical simulation model; obtaining a displacement efficiency-CO2 displacement pressure relationship curve and an interfacial tension-CO2 displacement pressure relationship curve corresponding to each preset water saturation degree according to the plurality of preset water saturation degrees, the plurality of preset CO2 displacement pressures, the plurality of simulated interfacial tensions and the plurality of simulated oil displacement efficiencies; determining a plurality of target fluid interaction state boundary CO2 displacement pressures corresponding to each preset water saturation degree according to the displacement efficiency-CO2 displacement pressure relationship curve and the interfacial tension-CO2 displacement pressure relationship curve corresponding to each preset water saturation degree, wherein the target fluid interaction state boundary CO2 displacement pressure is used to divide the fluid interaction state; obtaining a correspondence relationship between the CO2 displacement pressure and the fluid interaction state corresponding to each preset water saturation degree according to the plurality of target fluid interaction state boundary CO2 displacement pressures corresponding to each preset water saturation degree, so as to obtain the target correspondence relationship.

[0008] In the embodiments of the present application, the plurality of target fluid interaction state boundary CO2 displacement pressures comprises a first target fluid interaction state boundary CO2 displacement pressure, a second target fluid interaction state boundary CO2 displacement pressure and a third target fluid interaction state boundary CO2 displacement pressure; the determination of the plurality of target fluid interaction state boundary CO2 displacement pressures corresponding to each preset water saturation degree comprises: obtaining a non-miscible maximum oil displacement efficiency corresponding to each preset water saturation degree respectively; determining the CO2 displacement pressure corresponding to the non-miscible maximum oil displacement efficiency and the preset oil displacement efficiency based on the displacement efficiency-CO2 displacement pressure relationship curve corresponding to each preset water saturation degree, so as to obtain the first target fluid interaction state boundary CO2 displacement pressure and the second target fluid interaction state boundary CO2 displacement pressure; determining the CO2 displacement pressure corresponding to the preset interfacial tension based on the interfacial tension-CO2 displacement pressure relationship curve corresponding to each preset water saturation degree, so as to obtain the third target fluid interaction state boundary CO2 displacement pressure.

[0009] In the embodiment of the present application, the non-miscible maximum oil displacement efficiency corresponding to each preset water saturation is obtained by: obtaining the residual oil saturation and the original oil saturation corresponding to each preset water saturation; obtaining the saturation difference corresponding to each preset water saturation, wherein the saturation difference is the difference between the original oil saturation and the residual oil saturation; determining the non-miscible maximum oil displacement efficiency corresponding to each preset water saturation according to the saturation difference corresponding to each preset water saturation, wherein the non-miscible maximum oil displacement efficiency is the ratio of the saturation difference to the original oil saturation.

[0010] In the embodiment of the present application, the residual oil saturation and the original oil saturation corresponding to each preset water saturation are obtained by: obtaining the first oil-gas relative permeability curve corresponding to each preset water saturation based on the relative permeability experiment, wherein the first oil-gas relative permeability curve includes the gas saturation-oil phase relative permeability curve and the gas saturation-gas phase relative permeability curve; determining the residual oil saturation and the original oil saturation according to the gas saturation-oil phase relative permeability curve and the gas saturation-gas phase relative permeability curve, wherein the residual oil saturation is the deviation of the gas saturation when the oil phase relative permeability is zero on the gas saturation-oil phase relative permeability curve from 1, and the original oil saturation is the deviation of the gas saturation when the gas phase relative permeability is zero on the gas saturation-gas phase relative permeability curve from 1.

[0011] In the embodiment of the present application, the construction of the CO2-crude oil-water three-phase reservoir numerical simulation model includes: obtaining the target reservoir characteristics of the explored reservoir and the second oil-gas relative permeability curve corresponding to the explored reservoir, wherein the target reservoir characteristics include the average porosity and the average permeability, and the second oil-gas relative permeability curve is the oil-gas relative permeability curve when the water saturation is zero; obtaining the target oil-gas component according to the target reservoir characteristics, the pre-constructed CO2-crude oil two-phase fluid model, the second oil-gas relative permeability curve, the CO2 injection amount, the preset water saturation, and the preset CO2 displacement pressure based on the initial CO2-crude oil-water three-phase reservoir numerical simulation model; obtaining the target interfacial tension based on the preset interfacial tension algorithm according to the target oil-gas component; updating the second oil-gas relative permeability curve according to the target interfacial tension based on the pre-stored correspondence between the interfacial tension and the oil-gas relative permeability curve, to obtain the updated second oil-gas relative permeability curve corresponding to the explored reservoir; increasing the CO2 injection amount, and updating the initial CO2-crude oil-water three-phase reservoir numerical simulation model according to the updated second oil-gas relative permeability curve until the CO2 injection amount reaches the preset CO2 injection amount threshold.

[0012] In the embodiment of the present application, the CO2-crude oil two-phase fluid model is constructed, including: obtaining a CO2-crude oil one-dimensional numerical slim tube experiment model according to a preset oil-gas phase permeation curve and an initial CO2-crude oil two-phase fluid model; determining a plurality of numerical experiment model maximum oil displacement efficiencies according to a plurality of second preset CO2 displacement pressures based on the CO2-crude oil one-dimensional numerical slim tube experiment model; determining a second preset CO2 displacement pressure corresponding to a maximum of the plurality of numerical experiment model maximum oil displacement efficiencies as a critical CO2 displacement pressure; determining a deviation of the critical CO2 displacement pressure and a preset critical CO2 displacement pressure to obtain a critical CO2 displacement pressure error value; updating the initial CO2-crude oil two-phase fluid model until the critical CO2 displacement pressure error value is less than a preset pressure error threshold, to obtain the CO2-crude oil two-phase fluid model.

[0013] The second aspect of the embodiment of the present application provides a device for determining an oil reservoir fluid interaction state, including: a memory configured to store instructions; and a processor configured to call the instructions from the memory and capable of realizing the method for determining the oil reservoir fluid interaction state when executing the instructions.

[0014] The third aspect of the embodiment of the present application provides a machine readable storage medium, which stores instructions for causing a machine to execute the method for determining the oil reservoir fluid interaction state.

[0015] The fourth aspect of the embodiment of the present application provides a computer program product, including a computer program, which realizes the method for determining the oil reservoir fluid interaction state when executed by a processor. Other features and advantages of the embodiment of the present application will be described in detail in the following specific embodiment part.

[0016] The above technical solution determines the target corresponding relationship of the water saturation, the CO2 displacement pressure and the fluid interaction state in advance, then acquires the current water saturation and the current CO2 displacement pressure of the target oil reservoir, and determines the current fluid interaction state of the target oil reservoir according to the current water saturation and the current CO2 displacement pressure based on the determined target corresponding relationship of the water saturation, the CO2 displacement pressure and the fluid interaction state. The technical effect of improving the accuracy of the oil reservoir fluid interaction state classification result is realized. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings are included to provide a further understanding of the embodiments of the present application, and constitute a part of the specification, and are used together with the following specific embodiments to explain the embodiments of the present application, but do not constitute a limitation on the embodiments of the present application. In the drawings:

[0018] Figure 1A flowchart schematically showing a method for determining a state of interaction of reservoir fluids according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0019] To make the objectives, technical solutions, and superiorities of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. It should be understood that the specific embodiments described herein are merely intended to illustrate and explain the embodiments of the present application, and are not intended to limit the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0020] It should be noted that the acquisition, transmission, storage, use, processing, etc. of data in the technical solutions of the present application comply with relevant provisions of national laws and regulations. In the embodiments of the present application, some industry existing solutions such as software, components, models, etc. may be mentioned, which should be considered as exemplary, and the purpose is only to illustrate the feasibility of the implementation of the technical solutions of the present application, but it does not mean that the applicant has or will necessarily use the solutions.

[0021] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative positional relationship, motion condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications will also change accordingly.

[0022] In addition, if the embodiments of the present application involve descriptions of “first”, “second”, etc., the descriptions of “first”, “second”, etc. are only for description purposes, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by “first” and “second” can explicitly or implicitly include at least one of the features. In addition, the technical solutions of the various embodiments can be combined with each other, but must be based on the fact that a person of ordinary skill in the art can implement them, and when the combination of technical solutions contradicts each other or cannot be implemented, it should be considered that the combination of technical solutions does not exist and is not within the scope of protection claimed by the present application.

[0023] It should be noted that the acquisition, transmission, storage, use, processing, etc. of data in the technical solutions of the present application comply with relevant provisions of national laws and regulations. In the embodiments of the present application, some industry existing solutions such as software, components, models, etc. may be mentioned, which should be considered as exemplary, and the purpose is only to illustrate the feasibility of the implementation of the technical solutions of the present application, but it does not mean that the applicant has or will necessarily use the solutions.

[0024] It should be noted that the acquisition, transmission, storage, use, processing, etc. of data in the technical solutions of the present application comply with relevant provisions of national laws and regulations. In the embodiments of the present application, some industry existing solutions such as software, components, models, etc. may be mentioned, which should be considered as exemplary, and the purpose is only to illustrate the feasibility of the implementation of the technical solutions of the present application, but it does not mean that the applicant has or will necessarily use the solutions.Figure 1 A flowchart for determining the fluid interaction state of an oil reservoir is shown in an embodiment of the present application. As shown in Figure 1 The present application provides a method for determining the fluid interaction state of an oil reservoir. The method is described by taking a processor as an example. The method can include the following steps:

[0025] In step S101, the current water saturation and the current CO2 displacement pressure of the target oil reservoir are obtained.

[0026] In step S102, the current fluid interaction state of the target oil reservoir is determined according to the current water saturation and the current CO2 displacement pressure based on a predetermined target correspondence relationship among the water saturation, the CO2 displacement pressure and the fluid interaction state.

[0027] It can be understood that the target oil reservoir refers to the oil reservoir whose fluid interaction state is to be determined. The current water saturation refers to the water saturation of the target oil reservoir at present. The current CO2 displacement pressure refers to the oil displacement pressure of the target oil reservoir by using CO2 at present. The target correspondence relationship among the water saturation, the CO2 displacement pressure and the fluid interaction state refers to the correspondence relationship among the water saturation, the CO2 displacement pressure and the fluid interaction state. There is a corresponding fluid interaction state under different water saturations and CO2 displacement pressures. The current fluid interaction state refers to the fluid interaction state at present, including the non-miscible phase, the near-miscible phase, the miscible phase and the completely miscible phase.

[0028] Specifically, the present application can obtain the corresponding fluid interaction state according to the current water saturation and the current CO2 displacement pressure in the case that the target correspondence relationship among the water saturation, the CO2 displacement pressure and the fluid interaction state is known. The current water saturation is obtained by field exploration. The current CO2 displacement pressure is obtained by detection and is artificially set. The present application can obtain the target correspondence relationship among the water saturation, the CO2 displacement pressure and the fluid interaction state under the conditions that the water saturations are 0%, 15%, 30% and 60%. When the fluid interaction state of a specific water saturation needs to be determined, the target correspondence relationship corresponding to the water saturation closest to the specific water saturation is selected from the target correspondence relationships corresponding to the water saturations of 0%, 15%, 30% and 60%. For example, when the fluid interaction state of an oil reservoir with a water saturation of 42% needs to be determined, the target correspondence relationship corresponding to the water saturation of 30% is selected to determine the fluid interaction state.

[0029] The technical scheme above determines the target corresponding relationship of water saturation, CO2 displacement pressure and fluid interaction state in advance, then obtains the current water saturation and the current CO2 displacement pressure of the target reservoir, and determines the current fluid interaction state of the target reservoir based on the current water saturation and the current CO2 displacement pressure and the determined target corresponding relationship of water saturation, CO2 displacement pressure and fluid interaction state. The technical scheme realizes the technical effect of improving the accuracy of the classification result of the fluid interaction state of the reservoir.

[0030] In one embodiment, the determination of the target corresponding relationship comprises: obtaining a plurality of simulated interfacial tensions and a plurality of simulated oil displacement efficiencies based on a pre-constructed CO2-crude oil-water three-phase reservoir numerical simulation model according to a plurality of first preset CO2 displacement pressures and a plurality of preset water saturations; obtaining an oil displacement efficiency-CO2 displacement pressure relationship curve and an interfacial tension-CO2 displacement pressure relationship curve corresponding to each preset water saturation based on the plurality of preset water saturations, the plurality of preset CO2 displacement pressures, the plurality of simulated interfacial tensions and the plurality of simulated oil displacement efficiencies; determining a plurality of target fluid interaction state boundary CO2 displacement pressures corresponding to each preset water saturation based on the oil displacement efficiency-CO2 displacement pressure relationship curve and the interfacial tension-CO2 displacement pressure relationship curve corresponding to each preset water saturation, wherein the target fluid interaction state boundary CO2 displacement pressure is used for classifying the fluid interaction state; and obtaining a corresponding relationship between the CO2 displacement pressure and the fluid interaction state corresponding to each preset water saturation based on the plurality of target fluid interaction state boundary CO2 displacement pressures corresponding to each preset water saturation, so as to obtain the target corresponding relationship.

[0031] It can be understood that the CO2-oil-water three-phase reservoir numerical simulation model is a pre-constructed model. The first preset CO2 displacement pressure is a preset CO2 displacement pressure applied to the CO2-oil-water three-phase reservoir numerical simulation model. The preset water saturation is a preset water saturation. The simulated interfacial tension is an interfacial tension simulated by the CO2-oil-water three-phase reservoir numerical simulation model under a certain first preset CO2 displacement pressure and a preset water saturation. The simulated oil displacement efficiency is an oil displacement efficiency simulated by the CO2-oil-water three-phase reservoir numerical simulation model under a certain first preset CO2 displacement pressure and a preset water saturation. The oil displacement efficiency-CO2 displacement pressure relationship curve is a relationship curve of the first preset CO2 displacement pressure and the simulated oil displacement efficiency. The interfacial tension-CO2 displacement pressure relationship curve is a relationship curve between the first preset CO2 displacement pressure and the simulated interfacial tension. The target fluid interaction state boundary CO2 displacement pressure is a critical displacement pressure value between four fluid interaction states, which is used to divide the fluid interaction states. The target corresponding relationship is a corresponding relationship among the water saturation, the CO2 displacement pressure, and the fluid interaction state, and there is a corresponding fluid interaction state under different water saturations and CO2 displacement pressures.

[0032] Specifically, the present application inputs a plurality of first preset CO2 displacement pressures and a plurality of preset water saturations into the pre-constructed CO2-oil-water three-phase reservoir numerical simulation model, which can output a plurality of simulated interfacial tensions and a plurality of simulated oil displacement efficiencies. Under each preset water saturation, different first preset CO2 displacement pressures correspond to one simulated interfacial tension and one simulated oil displacement efficiency, and according to a plurality of first preset CO2 displacement pressures, a plurality of simulated interfacial tensions and a plurality of simulated oil displacement efficiencies are correspondingly output. Each preset water saturation corresponds to an oil displacement efficiency-CO2 displacement pressure relationship curve and an interfacial tension-CO2 displacement pressure relationship curve. Different preset water saturations correspond to different oil displacement efficiency-CO2 displacement pressure relationship curves and different interfacial tension-CO2 displacement pressure relationship curves. According to the obtained oil displacement efficiency-CO2 displacement pressure relationship curve and the interfacial tension-CO2 displacement pressure relationship curve, three target fluid interaction state boundary CO2 displacement pressures corresponding to each preset water saturation can be determined, and the three target fluid interaction state boundary CO2 displacement pressures can be used to divide the displacement pressure into four segments, corresponding to four different fluid interaction states, so as to achieve the effect of dividing the fluid interaction state according to the preset water saturation and the target fluid interaction state boundary CO2 displacement pressure, thereby obtaining the target corresponding relationship among the water saturation, the CO2 displacement pressure, and the fluid interaction state.

[0033] In one embodiment, the plurality of target fluid interaction state boundary CO2 displacement pressures include a first target fluid interaction state boundary CO2 displacement pressure, a second target fluid interaction state boundary CO2 displacement pressure, and a third target fluid interaction state boundary CO2 displacement pressure; the plurality of target fluid interaction state boundary CO2 displacement pressures corresponding to each preset water saturation are determined according to the oil displacement efficiency-CO2 displacement pressure relationship curve and the interfacial tension-CO2 displacement pressure relationship curve corresponding to each preset water saturation, including: obtaining the non-miscible maximum oil displacement efficiency corresponding to each preset water saturation; determining the CO2 displacement pressure corresponding to the non-miscible maximum oil displacement efficiency and the preset oil displacement efficiency based on the oil displacement efficiency-CO2 displacement pressure relationship curve corresponding to each preset water saturation, to obtain the first target fluid interaction state boundary CO2 displacement pressure and the second target fluid interaction state boundary CO2 displacement pressure; determining the CO2 displacement pressure corresponding to the preset interfacial tension based on the interfacial tension-CO2 displacement pressure relationship curve corresponding to each preset water saturation, to obtain the third target fluid interaction state boundary CO2 displacement pressure.

[0034] It can be understood that the first target fluid interaction state boundary CO2 displacement pressure is the boundary CO2 displacement pressure between the non-fluid interaction state and the near-fluid interaction state. The second target fluid interaction state boundary CO2 displacement pressure is the boundary CO2 displacement pressure between the near-fluid interaction state and the fluid interaction state. The third target fluid interaction state boundary CO2 displacement pressure is the boundary CO2 displacement pressure between the fluid interaction state and the complete fluid interaction state. The non-miscible maximum oil displacement efficiency is the maximum oil displacement efficiency in the non-fluid interaction state. The preset oil displacement efficiency can be 90% of the oil displacement efficiency, which is a preset oil displacement efficiency, used to determine the CO2 displacement pressure corresponding to the preset oil displacement efficiency as the second target fluid interaction state boundary CO2 displacement pressure. The preset interfacial tension is 0, which is a preset interfacial tension, used to determine the CO2 displacement pressure corresponding to the preset interfacial tension as the third target fluid interaction state boundary CO2 displacement pressure. The oil displacement efficiency-CO2 displacement pressure relationship curve is a relationship curve between the first preset CO2 displacement pressure and the simulated oil displacement efficiency. The interfacial tension-CO2 displacement pressure relationship curve is a relationship curve between the first preset CO2 displacement pressure and the simulated interfacial tension.

[0035] Specifically, the processor of the application first obtains the maximum oil displacement efficiency in immiscible phase corresponding to each preset water saturation; on the oil displacement efficiency-CO2 displacement pressure relationship curve corresponding to each preset water saturation, two CO2 displacement pressures corresponding to the maximum oil displacement efficiency in immiscible phase and 90% oil displacement efficiency are found. The two CO2 displacement pressures are the first target fluid interaction state boundary CO2 displacement pressure and the second target fluid interaction state boundary CO2 displacement pressure, that is, the boundary CO2 displacement pressure between the non-fluid interaction state and the near-fluid interaction state and the boundary CO2 displacement pressure between the near-fluid interaction state and the fluid interaction state are obtained. On the interfacial tension-CO2 displacement pressure relationship curve corresponding to each preset water saturation, the CO2 displacement pressure corresponding to the point of 0 interfacial tension is determined to obtain the boundary CO2 displacement pressure between the fluid interaction state and the complete fluid interaction state. Therefore, the application can divide the fluid interaction state into immiscible phase, near-miscible phase, miscible phase and complete miscible phase according to the multiple target fluid interaction state boundary CO2 displacement pressures considering the influence of water saturation.

[0036] In one embodiment, obtaining the maximum oil displacement efficiency in immiscible phase corresponding to each preset water saturation comprises: obtaining the residual oil saturation and the original oil saturation corresponding to each preset water saturation; obtaining the saturation difference value corresponding to each preset water saturation, wherein the saturation difference value is the difference between the original oil saturation and the residual oil saturation; determining the maximum oil displacement efficiency in immiscible phase corresponding to each preset water saturation according to the saturation difference value corresponding to each preset water saturation, wherein the maximum oil displacement efficiency in immiscible phase is the ratio of the saturation difference value to the original oil saturation.

[0037] It can be understood that the preset water saturation is a pre-set water saturation. The residual oil saturation is the residual oil phase saturation in the model. The original oil saturation is the original oil phase saturation in the model. The saturation difference value is the difference between the original oil saturation and the residual oil saturation. The maximum oil displacement efficiency in immiscible phase refers to the maximum oil displacement efficiency in the non-fluid interaction state.

[0038] Specifically, the residual oil saturation and the original oil saturation corresponding to each preset water saturation are obtained; the maximum oil displacement efficiency in immiscible phase is calculated by obtaining the ratio of the saturation difference value corresponding to each preset water saturation to the original oil saturation. The application can achieve the effect of dividing the fluid interaction state by determining the maximum oil displacement efficiency in immiscible phase.

[0039] In one embodiment, the residual oil saturation and the original oil saturation corresponding to each preset water saturation are obtained, comprising: obtaining a first oil-gas relative permeability curve corresponding to each preset water saturation based on the phase permeability experiment, wherein the first oil-gas relative permeability curve includes a gas saturation-oil phase relative permeability curve and a gas saturation-gas phase relative permeability curve; determining the residual oil saturation and the original oil saturation according to the gas saturation-oil phase relative permeability curve and the gas saturation-gas phase relative permeability curve, wherein the residual oil saturation is the deviation of the gas saturation when the oil phase relative permeability is zero on the gas saturation-oil phase relative permeability curve from 1, and the original oil saturation is the deviation of the gas saturation when the gas phase relative permeability is zero on the gas saturation-gas phase relative permeability curve from 1.

[0040] It can be understood that the first oil-gas relative permeability curve is the oil phase relative permeability curve and the gas phase relative permeability curve when the water saturation is not 0. The first oil-gas relative permeability curve includes the gas saturation-oil phase relative permeability curve and the gas saturation-gas phase relative permeability curve.

[0041] Specifically, according to the first oil-gas relative permeability curve, the gas saturation when the oil phase relative permeability is zero and the gas saturation when the gas phase relative permeability is zero can be obtained. The residual oil saturation and the original oil saturation are represented by the deviation of the two gas saturations from 1, and then the maximum oil displacement efficiency of immiscible phase is obtained, so as to subsequently divide the fluid interaction state.

[0042] In one embodiment, the construction of a CO2-crude oil-water three-phase reservoir numerical simulation model comprises: obtaining target reservoir characteristics of an explored reservoir and a second oil-gas relative permeability curve corresponding to the explored reservoir, wherein the target reservoir characteristics include average porosity and average permeability, and the second oil-gas relative permeability curve is an oil-gas relative permeability curve when the water saturation is zero; based on an initial CO2-crude oil-water three-phase reservoir numerical simulation model, obtaining target oil-gas components according to the target reservoir characteristics, a pre-constructed CO2-crude oil two-phase fluid model, the second oil-gas relative permeability curve, a CO2 injection amount, a preset water saturation, and a preset CO2 displacement pressure; obtaining a target interfacial tension based on a preset interfacial tension algorithm according to the target oil-gas components; updating the second oil-gas relative permeability curve according to the target interfacial tension based on a pre-stored corresponding relationship between the interfacial tension and the oil-gas relative permeability curve, to obtain an updated second oil-gas relative permeability curve corresponding to the explored reservoir; increasing the CO2 injection amount, and updating the initial CO2-crude oil-water three-phase reservoir numerical simulation model according to the updated second oil-gas relative permeability curve, until the CO2 injection amount reaches a preset CO2 injection amount threshold.

[0043] It can be understood that the target reservoir characteristics include average porosity and average permeability. The second oil-gas phase permeability curve is an oil-gas phase permeability curve when the water saturation is zero, and the second oil-gas phase permeability curve includes a gas saturation-oil phase relative permeability curve and a gas saturation-gas phase relative permeability curve. The target oil-gas component is an oil-gas component output according to the initial CO2-crude oil-water three-phase reservoir numerical simulation model. The target interfacial tension is an interfacial tension calculated according to the target oil-gas component. The preset CO2 injection amount threshold can be 1.2 PV.

[0044] Specifically, the CO2-crude oil-water three-phase reservoir numerical simulation model of the present application is a model that is continuously updated before the CO2 injection amount reaches the preset CO2 injection amount threshold, and the target interfacial tension is obtained according to the target oil-gas component. Based on the pre-stored correspondence between the interfacial tension and the oil-gas phase permeability curve, the second oil-gas phase permeability curve is updated according to the target interfacial tension to obtain an updated second oil-gas phase permeability curve corresponding to the explored reservoir, and the initial CO2-crude oil-water three-phase reservoir numerical simulation model is updated according to the updated second oil-gas phase permeability curve. The pre-stored correspondence between the interfacial tension and the oil-gas phase permeability curve is based on the correspondence between the interfacial tension when the water saturation is 0 and the fluid interaction state. The present application obtains the corresponding fluid interaction state through the target interfacial tension, and then selects the corresponding oil-gas phase permeability curve through the fluid interaction state according to the correspondence between the fluid interaction state and the oil-gas phase permeability curve, to update the second oil-gas phase permeability curve. The present application continuously updates the CO2-crude oil-water three-phase reservoir numerical simulation model by updating the oil-gas phase permeability curve under the condition of continuous CO2 injection, which can improve the accuracy of the model.

[0045] In one embodiment, the construction of the CO2-crude oil two-phase fluid model includes: obtaining a CO2-crude oil one-dimensional numerical fine tube experiment model according to the preset oil-gas phase permeability curve and the initial CO2-crude oil two-phase fluid model; determining a plurality of numerical experiment model maximum oil displacement efficiencies according to a plurality of second preset CO2 displacement pressures based on the CO2-crude oil one-dimensional numerical fine tube experiment model; determining that the second preset CO2 displacement pressure corresponding to the maximum of the plurality of numerical experiment model maximum oil displacement efficiencies is the critical CO2 displacement pressure; determining the deviation of the critical CO2 displacement pressure and the preset critical CO2 displacement pressure to obtain a critical CO2 displacement pressure error value; and updating the initial CO2-crude oil two-phase fluid model until the critical CO2 displacement pressure error value is less than a preset pressure error threshold to obtain the CO2-crude oil two-phase fluid model.

[0046] It can be understood that the preset oil-gas phase permeation curve refers to a preset oil phase relative permeability curve and a gas phase relative permeability curve with a water saturation of zero. The initial CO2-crude oil two-phase fluid model is an initial CO2-crude oil two-phase fluid model. The second preset CO2-displacement pressure is a preset CO2-displacement pressure for determining the critical CO2-displacement pressure. The preset critical CO2-displacement pressure is a preset critical CO2-displacement pressure, which can be obtained according to a slim tube experiment. The preset pressure error threshold is a preset pressure error threshold.

[0047] Specifically, the CO2-crude oil two-phase fluid model is used for construction of a CO2-crude oil-water three-phase reservoir numerical simulation model. The processor obtains a CO2-crude oil one-dimensional numerical slim tube experiment model according to the preset oil-gas phase permeation curve and the initial CO2-crude oil two-phase fluid model. The processor determines the critical CO2-displacement pressure through the CO2-crude oil one-dimensional numerical slim tube experiment model, and determines the deviation of the critical CO2-displacement pressure and the preset critical CO2-displacement pressure to obtain a critical CO2-displacement pressure error value. When the critical CO2-displacement pressure error value is greater than the preset pressure error threshold, the initial CO2-crude oil two-phase fluid model is updated to obtain the CO2-crude oil two-phase fluid model. As can be seen, the processor uses the critical CO2-displacement pressure obtained from the CO2-crude oil one-dimensional numerical slim tube experiment model constructed according to the CO2-crude oil two-phase fluid model to verify whether the CO2-crude oil two-phase fluid model used is correct. Through the above steps, the correctness of the CO2-crude oil two-phase fluid model can be verified.

[0048] The specific steps can be as follows:

[0049] Step 1: Determine the CO2-crude oil minimum miscibility pressure through a CO2-crude oil slim tube experiment, and establish a CO2-crude oil two-phase fluid model.

[0050] The slim tube experiment is one of the currently recognized methods for determining the CO2-crude oil minimum miscibility pressure. Through the CO2-crude oil slim tube experiment, the minimum miscibility pressure under two-phase conditions is determined, and combined with the results of chromatography, PVT, etc., a CO2-crude oil two-phase fluid model is established by using a numerical simulation method. The steps include:

[0051] Step 1-1: Sample the target reservoir formation fluid to obtain target reservoir representative crude oil and formation water samples;

[0052] Sampling is carried out on site in the target reservoir to obtain typical oil and water samples and gas samples of the target reservoir, and the samples are subjected to quality inspection to make them representative. When sampling, the sampling pressure should be higher than the crude oil saturation pressure to prevent the crude oil from degassing and causing deviation in the test results of components.

[0053] Step 1-2: Determine the composition of the crude oil by gas chromatography experiment;

[0054] Using typical oil and gas samples, gas chromatography experiments were carried out by Agilent 7890A experimental device to determine the composition of the oil and gas samples, and the experimental data was sorted out to check whether the molar fraction of each component added up to 100%. According to the experimental results, the experimental oil was compounded, and the gas-oil ratio of the compounded experimental oil was tested.

[0055] Step 1-3: Determine the phase characteristics of the crude oil under different concentrations of CO2 by conventional crude oil PVT experiment and CO2 injection-crude oil PVT experiment;

[0056] Conventional PVT experiments and CO2 injection-crude oil PVT experiments were carried out using the compounded experimental oil. The conventional PVT experiments included: gravimetric expansion, multiple degassing, density testing, etc. The CO2 injection-crude oil PVT experiments included: crude oil volume expansion test and crude oil viscosity test. By sorting out the experimental data, it was determined whether the saturation pressure, density, viscosity, etc. of the crude oil sample were the same as those of the target crude oil.

[0057] Step 1-4: Obtain the relationship curve between oil displacement efficiency and displacement pressure by CO2-crude oil slim tube experiment, and determine the minimum miscibility pressure of CO2-crude oil;

[0058] CO2-crude oil slim tube experiments were carried out, 5 pressure points were tested above the formation saturation pressure, and the oil displacement efficiency was calculated after injecting 1.2 PV of CO2. When the crude oil recovery degree exceeds 90%, the minimum miscibility pressure of CO2-crude oil is determined by linear regression method. The slim tube experiment parameters are: length 20 m, inner diameter 4.0 mm, thickness 1.0 mm, filler 170-325 mesh, porosity 36.36%, permeability 3.986 D.

[0059] Step 1-5: According to the principle of similar properties, the crude oil components are split to obtain pseudo-components representing the properties of the target reservoir formation fluid, as shown in Table 1.

[0060] In order to improve the calculation efficiency and ensure the simulation accuracy of numerical simulation, the component splitting method is used to merge the crude oil components with similar properties into one category (especially the components with high carbon atom number are merged into Cn+). After splitting the crude oil components, simple pseudo-components representing the properties of the target reservoir formation fluid are obtained. By comparing the pseudo-components with the crude oil phase diagram, it is determined whether the pseudo-components are reasonable.

[0061] Step 1-6: Based on the pseudo-component, PVT and slim tube experiment results, the characteristic parameters of each pseudo-component are obtained, and a CO2-crude oil fluid model is established, as shown in Table 2.

[0062] Through the above experiments, the phase state fitting is carried out by using the WINPROP module of the CMG software, the characteristic parameters are continuously adjusted so that the simulation results are in good agreement with the phase state experimental results, the characteristic parameters of the state equation of each pseudo-component are obtained, and thus the CO2-crude oil fluid model is established, which is used for subsequent simulation calculation.

[0063] Step 2: Through the CO2-crude oil numerical slim tube experiment, the CO2-oil displacement efficiency, interfacial tension and displacement pressure relationship curve under two-phase conditions are obtained, and the CO2-crude oil fluid model is verified.

[0064] Due to the unstable sand filling structure of the sand filling pipe in the slim tube experiment, the physical property is preferred, and the low permeability reservoir pore structure characteristics cannot be accurately characterized. In order to avoid the experimental result error caused by such factors, the numerical simulation method is adopted to measure the minimum miscibility pressure, the CO2-oil displacement efficiency, interfacial tension and displacement pressure relationship curve are obtained, and the correctness of the CO2-crude oil fluid model is verified.

[0065] Step 2-1: The target oil reservoir core is sampled to obtain the representative core sample of the target oil reservoir;

[0066] The core sample of the target reservoir is sampled on site, the integrity, length and other quality of the core sample are checked to make it representative. When sampling, the core breakage caused by pressure change should be prevented.

[0067] Step 2-2: Through the relative permeability experiment, the oil-water and oil-gas relative permeability curves are obtained;

[0068] The representative core sample of the target reservoir is used to carry out the relative permeability test experiment, and the oil-water and oil-gas relative permeability curves are obtained, which are used for numerical simulation and improve the accuracy of the simulation results.

[0069] Step 2-3: Based on the CO2-crude oil fluid model and the relative permeability curve, a CO2-crude oil numerical slim tube experiment model is established;

[0070] Based on the CO2-crude oil fluid model and the CO2-crude oil relative permeability curve, a one-dimensional slim tube flow numerical experiment model is established combined with the actual slim tube geometric size. The model parameters are as follows: the displacement direction length is 20 m, the grid number is 200, the step length is 10 cm, the cross section is square with a side length of 4 mm. The average porosity is 12.5%, and the average permeability is 3000 mD. One injection well and one production well are respectively arranged at both ends of the model, and the simulation is ended when the injected CO2 amount reaches 1.2 PV.

[0071] Step 2-4: Through CO2-crude oil numerical slim tube experiments under different pressures, the oil displacement efficiency, interfacial tension and displacement pressure relationship curves are obtained, the error between the simulation results and the experimental results is calculated, and the correctness of the CO2-crude oil fluid model is verified;

[0072] Referring to the slim tube experiment method, CO2-crude oil miscibility pressure tests under different pressures are carried out using a numerical slim tube model, the oil displacement efficiency, interfacial tension and displacement pressure relationship curves are obtained, the minimum miscibility pressure obtained by linear regression is determined, and the different fluid interaction state intervals are determined. Compared with the slim tube experiment results, the relative error is calculated. At the same time, the correctness of the CO2-crude oil fluid model is verified.

[0073] Step 2-5: Based on the oil displacement efficiency, interfacial tension and displacement pressure relationship curves, the maximum oil displacement efficiency, critical interfacial tension and pressure threshold corresponding to different fluid interaction states of CO2-crude oil two-phase are determined.

[0074] Based on the oil displacement efficiency, interfacial tension and displacement pressure relationship curves obtained by simulation, the range of different fluid interaction states under the condition of CO2-crude oil two-phase, and the maximum oil displacement efficiency, critical interfacial tension and pressure threshold corresponding to different fluid interaction states are determined. The simulation result is default to water saturation of 0, which can be compared with the simulation result under the condition of subsequent water saturation, in order to analyze the influence of different water saturations on fluid interaction state.

[0075] Step 3: Through reservoir numerical simulation, the relationship curves of CO2 oil displacement efficiency, interfacial tension and displacement pressure under three-phase conditions are obtained, and the influence of different water saturations on CO2-crude oil fluid interaction state is judged and characterized.

[0076] The numerical slim tube experiment is based on a one-dimensional numerical slim tube model, and the porosity, permeability and other parameters are referenced from the slim tube experiment results. The fluid does not consider water saturation. Therefore, in order to accurately judge and characterize the influence of different water saturations on CO2-crude oil fluid interaction state, three-dimensional reservoir numerical simulation is carried out.

[0077] Step 3-1: Based on the characteristics of the target reservoir, the fluid model and the relative permeability curve, a CO2-crude oil-water three-phase reservoir numerical simulation model is established;

[0078] According to the physical properties of the target reservoir (mainly including: average porosity 12.5%, average permeability 7.57 mD, etc.), combined with the fluid model and the relative permeability curve, a CO2-crude oil-water three-phase reservoir numerical simulation model suitable for CO2 flooding is established, and component numerical simulation is carried out using the GEM module of CMG software. In this model, the change of water saturation is considered, and Sw=15%, 30% and 60% are taken to simulate low, medium and high water saturation conditions.

[0079] Step 3-2: Through the numerical simulation of the reservoir under different water saturation conditions, the fluid composition change in each grid at each time of the model is obtained, and the CO2-oil interaction is calculated by applying the equation of state (Formula 1-1) to determine the change of oil-gas interfacial tension;

[0080] (1-1)

[0081] Wherein, σ is the oil-gas interfacial tension; Nc is the oil phase component; [P]i is the unit conversion coefficient; bLm and bvm are the phase densities of oil component and gas component respectively; x i and y i are the phase mole fractions of oil component and gas component of each component respectively; t is the different simulation time.

[0082] In the CO2 displacement simulation, due to the influence of water saturation, the fluid composition in the grid becomes more complex, and it is difficult to accurately determine the fluid interaction state of CO2-oil. Therefore, in order to obtain the CO2-oil interfacial tension, the equation of state is applied to calculate the CO2-oil interaction, and the oil-gas interfacial tension at different times is determined, and the calculation formula is shown in Formula 1-1.

[0083] Step 3-3: Through the change of oil-gas interfacial tension, the phase permeability curve interpolation method is used to finely capture the dynamic change of fluid interaction state, and the oil displacement efficiency, interfacial tension and pressure relationship curve of different fluid interaction states under different water saturations are obtained;

[0084] In this case, the oil displacement efficiency and interfacial tension are mainly considered to determine the fluid interaction state. However, different fluid interaction states affect the CO2 displacement efficiency, which is most directly reflected in the change of phase permeability curve in numerical simulation. Therefore, the phase permeability curve interpolation method is used for simulation for different fluid interaction states, and Formula 1-2 is used to determine the phase permeability curve for different fluid interaction states. The initial oil-gas phase permeability curve is used at the beginning; when it is in the near fluid interaction state, the phase permeability curve between the miscible and immiscible phases is used for simulation; when it is in the miscible and complete fluid interaction state, the phase permeability curve at the miscible time is used for simulation, and the interfacial tension needs to be further judged at this time. When the interfacial tension is 0, it is in the complete fluid interaction state, and the oil displacement efficiency is greater. When the interfacial tension is not 0, it is in the fluid interaction state, and the oil displacement efficiency is slightly lower.

[0085] Step 3-4: Through the simulation results, the oil displacement efficiency and interfacial tension of CO2-oil under different fluid interaction states under different water saturations are obtained, and the influence of different water saturations on the pressure threshold of CO2-oil under different fluid interaction states is determined;

[0086] Through numerical simulation, the relationship curves of oil displacement efficiency and interfacial tension with pressure change of CO2-crude oil under different fluid interaction states at different water saturation are obtained, the influence of water saturation on CO2-crude oil miscibility is determined, and the threshold change of miscibility pressure of CO2 and crude oil is judged, so as to determine the fluid interaction state in the reservoir.

[0087] Step 3-5: The influence of different water saturation on CO2 oil displacement under different fluid interaction states is obtained by calculating the crude oil mobility improvement effect (formula 1-2), which is used to characterize the CO2 oil displacement mechanism under different fluid interaction states and to determine the main controlling factors affecting displacement efficiency.

[0088] (1-2)

[0089] Wherein, △f is the crude oil mobility improvement effect; K is the reservoir permeability in the grid; μ is the reservoir crude oil viscosity.

[0090] One of the CO2 oil displacement mechanisms is to reduce the viscosity of crude oil to improve the flow ability of crude oil. However, under different fluid interaction state conditions, the improvement effect of CO2 on the viscosity of crude oil is different. Therefore, different fluid interaction states of CO2-crude oil play a crucial role in the development effect of CO2 flooding, and the development effect of CO2 flooding is measured by calculating the improvement effect of crude oil mobility. The change of crude oil mobility is calculated by formula 1-2 to represent the improvement degree of crude oil mobility under different fluid interaction states, to determine the CO2 displacement mechanism at different stages, and to determine the main controlling factors affecting displacement efficiency.

[0091] Step 4: Based on the judgment and characterization method of CO2-crude oil fluid interaction state under different water saturation, such as Table 3, the CO2 flooding engineering application after water flooding in low permeability reservoir is carried out.

[0092] Through the above method, the fluid interaction state judgment and characterization of CO2 flooding after water flooding in low permeability reservoir can be used to guide the optimization design of development scheme, maximize the recovery of crude oil, reduce the economic cost, and maximize the benefit.

[0093] Table 1 Formation crude oil composition and pseudo-component division

[0094]

[0095] Table 2 PVT experimental results of formation crude oil

[0096]

[0097] Table 3 Classification standard of different fluid interaction states under different water saturation conditions

[0098]

[0099] The second aspect of the embodiments of the present application provides a device for determining the interaction state of reservoir fluids, comprising: a memory configured to store instructions; and a processor configured to call the instructions from the memory and implement the method for determining the interaction state of reservoir fluids as described above when executing the instructions.

[0100] The third aspect of the embodiments of the present application provides a machine readable storage medium, which has instructions stored thereon, the instructions being used to cause a machine to execute the method for determining the interaction state of reservoir fluids as described above.

[0101] The fourth aspect of the embodiments of the present application provides a computer program product, which comprises a computer program, the computer program being used to implement the method for determining the interaction state of reservoir fluids as described above when executed by a processor. Other features and advantages of the embodiments of the present application will be described in detail in the following specific embodiments.

[0102] It should also be noted that the terms "comprising", "containing", or any other variant thereof are intended to cover non-exclusive inclusion, so that processes, methods, articles or devices that include a series of elements not only include those elements, but also include other elements not explicitly listed, or inherent to such processes, methods, articles or devices. Without more limitations, the element defined by the phrase "comprising a" does not exclude the presence of additional identical elements in the process, method, article or device that includes the element.

[0103] The above is only an embodiment of the present application and is not intended to limit the present application. The present application can have various changes and modifications for those skilled in the art. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the scope of claims of the present application.

Claims

1. A method for determining the interaction state of reservoir fluids, characterized in that, The method includes: Obtain the current water saturation and current CO2 displacement pressure of the target reservoir; Based on the predetermined target correspondence between water saturation, CO2 displacement pressure and fluid interaction state, the current fluid interaction state of the target reservoir is determined according to the current water saturation and the current CO2 displacement pressure. The determination of the target correspondence includes: Based on a pre-constructed numerical simulation model of a CO2-crude oil-water three-phase reservoir, multiple simulated interfacial tensions and multiple simulated oil displacement efficiencies are obtained according to multiple first preset CO2 displacement pressures and multiple preset water saturation. Based on multiple preset water saturation levels, multiple preset CO2 displacement pressures, multiple simulated interfacial tensions, and multiple simulated oil displacement efficiencies, the oil displacement efficiency-CO2 displacement pressure relationship curves and interfacial tension-CO2 displacement pressure relationship curves corresponding to each preset water saturation level are obtained. Based on the oil displacement efficiency-CO2 displacement pressure relationship curve and the interfacial tension-CO2 displacement pressure relationship curve corresponding to each preset water saturation, the CO2 displacement pressure of multiple target fluid interaction state limits corresponding to each preset water saturation is determined, wherein the target fluid interaction state limit CO2 displacement pressure is used to divide the fluid interaction state. Based on the CO2 displacement pressure corresponding to each preset water saturation level and multiple target fluid interaction state limits, the correspondence between the CO2 displacement pressure and the fluid interaction state corresponding to each preset water saturation level is obtained, so as to obtain the target correspondence. The construction of the numerical simulation model for the CO2-crude oil-water three-phase reservoir includes: The target reservoir characteristics of the explored reservoir and the corresponding second oil-gas phase permeability curve are obtained. The target reservoir characteristics include average porosity and average permeability. The second oil-gas phase permeability curve is the oil-gas phase permeability curve when the water saturation is zero. Based on the initial CO2-crude oil-water three-phase reservoir numerical simulation model, the target oil and gas composition is obtained according to the target reservoir characteristics, the pre-constructed CO2-crude oil two-phase fluid model, the second oil and gas phase permeation curve, the CO2 injection rate, the preset water saturation, and the preset CO2 displacement pressure. Based on a preset interfacial tension algorithm, the target interfacial tension is obtained according to the target oil and gas components; Based on the pre-stored correspondence between interfacial tension and hydrocarbon phase permeability curves, the second hydrocarbon phase permeability curve is updated according to the target interfacial tension to obtain the updated second hydrocarbon phase permeability curve corresponding to the explored reservoir. Increase the CO2 injection rate and update the initial CO2-crude oil-water three-phase reservoir numerical simulation model according to the updated second oil-gas phase permeability curve until the CO2 injection rate reaches the preset CO2 injection rate threshold.

2. The method according to claim 1, characterized in that, The multiple target fluid interaction state boundary CO2 displacement pressures include a first target fluid interaction state boundary CO2 displacement pressure, a second target fluid interaction state boundary CO2 displacement pressure, and a third target fluid interaction state boundary CO2 displacement pressure; determining the multiple target fluid interaction state boundary CO2 displacement pressures corresponding to each of the preset water saturation levels based on the oil displacement efficiency-CO2 displacement pressure relationship curve and the interfacial tension-CO2 displacement pressure relationship curve includes: Obtain the maximum immiscible oil displacement efficiency corresponding to each of the preset water saturation levels; Based on the oil displacement efficiency-CO2 displacement pressure relationship curves corresponding to each preset water saturation, the CO2 displacement pressures corresponding to the maximum oil displacement efficiency of the immiscible phase and the preset oil displacement efficiency are determined, so as to obtain the first target fluid interaction state limit CO2 displacement pressure and the second target fluid interaction state limit CO2 displacement pressure. Based on the interfacial tension-CO2 displacement pressure relationship curves corresponding to the preset water saturation, the CO2 displacement pressure corresponding to the preset interfacial tension is determined to obtain the CO2 displacement pressure of the third target fluid interaction state boundary.

3. The method according to claim 2, characterized in that, The step of obtaining the maximum immiscible oil displacement efficiency corresponding to each of the preset water saturation levels includes: Obtain the residual oil saturation and original oil saturation corresponding to each of the preset water saturation; Obtain the saturation difference value corresponding to each of the preset water saturation values, wherein the saturation difference value is the difference between the original oil saturation value and the residual oil saturation value; The maximum immiscible oil displacement efficiency corresponding to each preset water saturation is determined based on the saturation difference corresponding to each preset water saturation, wherein the maximum immiscible oil displacement efficiency is the ratio of the saturation difference to the original oil saturation.

4. The method according to claim 3, characterized in that, The step of obtaining the residual oil saturation and original oil saturation corresponding to each of the preset water saturation includes: Based on the phase permeation experiment, the first oil-gas phase permeation curves corresponding to each of the preset water saturation are obtained. The first oil-gas phase permeation curves include the gas saturation-oil phase relative permeability curve and the gas saturation-gas phase relative permeability curve. Based on the gas saturation-oil phase relative permeability curve and the gas saturation-gas phase relative permeability curve, the residual oil saturation and the original oil saturation are determined, wherein the residual oil saturation is the deviation of the gas saturation at which the oil phase relative permeability is zero on the gas saturation-oil phase relative permeability curve from 1, and the original oil saturation is the deviation of the gas saturation at which the gas phase relative permeability is zero on the gas saturation-gas phase relative permeability curve from 1.

5. The method according to claim 1, characterized in that, The construction of the CO2-crude oil two-phase fluid model includes: Based on the preset oil-gas phase permeation curve and the initial CO2-crude oil two-phase fluid model, a one-dimensional numerical capillary experimental model of CO2-crude oil was obtained. Based on the CO2-crude oil one-dimensional numerical capillary experimental model, the maximum oil displacement efficiency of multiple numerical experimental models is determined according to multiple second preset CO2 displacement pressures. The second preset CO2 displacement pressure corresponding to the largest of the maximum oil displacement efficiencies among the multiple numerical experimental models is determined as the critical CO2 displacement pressure; The deviation between the critical CO2 displacement pressure and the preset critical CO2 displacement pressure is determined to obtain the critical CO2 displacement pressure error value. The initial CO2-crude oil two-phase fluid model is updated until the critical CO2 displacement pressure error value is less than the preset pressure error threshold, so as to obtain the CO2-crude oil two-phase fluid model.

6. An apparatus for determining the interaction state of reservoir fluids, characterized in that, include: The memory is configured to store instructions; as well as The processor is configured to retrieve the instructions from the memory and, when executing the instructions, to implement the method for determining the reservoir fluid interaction state according to any one of claims 1 to 5.

7. A machine-readable storage medium, characterized in that, The machine-readable storage medium stores instructions for causing the machine to perform a method for determining the reservoir fluid interaction state according to any one of claims 1 to 5.

8. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the method for determining the reservoir fluid interaction state according to any one of claims 1 to 5.

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