Multi-element gas-driven multi-component leading edge and evolution law characterization method thereof

Abstract

The invention provides a characterization method for a multi-element gas drive multi-component front edge and an evolution law thereof, and the characterization method comprises the steps: building a multi-element gas drive multi-component oil reservoir mechanism model according to geological parameters of a research block, and carrying out multi-element gas drive oil reservoir numerical simulation; before the front edge of each component is propelled to a production well, dividing the front edge of each component based on a simulation result, drawing a visual front edge propulsion line, and carrying out regional division on the on-way distribution rule of an oil phase, a gas phase and each component; the method comprises the following steps: extracting saturation and component content data on a main stream line once at an interval of an injection rate step length or a time step length until the front edges of all components are pushed to a production well, drawing a change relation of the distance between the front edges of the components and the injection and production well along with the injection rate or the injection time, quantitatively representing a spatio-temporal evolution rule of the front edges of the components, and calculating the content of the components. Dividing different mining stages of multi-element gas drive, and determining duration of the different mining stages. According to the method, the accuracy of multi-component leading edge breakthrough prediction is improved, and quantitative characterization of multi-component leading edge spatio-temporal evolution is realized.

Description

Technical Field

[0001] The invention relates to the technical field of reservoir gas injection development, and in particular to a method for characterizing a multi-component front of a multi-element gas drive and its evolution law. Background Art

[0002] Since the discovery of natural CO2 gas reservoirs in the United States in the 1980s, CO2 miscible flooding has gradually developed. Entering the 1990s, the output of gas-injected crude oil has steadily increased, among which CO2 miscible flooding has the most outstanding effect, and the gas injection EOR technology has gradually matured. Subsequently, in the context of greenhouse gas emission reduction in response to climate change, the industry gradually reached a consensus on the concept of CO2 injection and storage, and the number of CO2 flooding projects and the proportion of production have increased year by year. The large-scale successful implementation on site has made CO2 flooding one of the most attractive EOR technologies in gas flooding. After decades of development, the supporting processes have been increasingly improved, and the implementation effect of gas-driven oil field development has been remarkable, and its contribution to global EOR production has increased year by year.

[0003] Although CO2 flooding has achieved good results, CO2 flooding technology is limited by the gas source and the properties of CO2 gas itself. For oil fields far away from cities and CO2 gas sources, the cost of CO2 separation, purification and transportation is still high, and its large-scale promotion and application is still difficult. This limits the development of CO2 flooding. On the other hand, some oil fields are close to power plants, coal plants, etc., with rich flue gas resources; and during the production process of oil fields, production wells will have a large amount of associated gas output. These flue gas and associated gas resources are mixed with CO2 with good oil recovery effect to form multi-gas (mainly N2, CO2, CH4, etc.) and injected back into the ground to form multi-gas flooding technology. While improving oil recovery, it can also achieve efficient utilization of resources such as flue gas and oil field associated gas.

[0004] Accurately dividing the gas drive front and quantitatively characterizing the evolution law of the front play an important guiding role in accurately predicting the time of gas breakthrough and gas channeling, effectively evaluating the potential of residual oil tapping, and rationally optimizing the subsequent expansion technology. The related research on the division of the gas drive front and the characterization of its evolution law in the existing technology is almost all based on the relevant means or methods proposed by CO2 drive. At present, there is still a lack of understanding of the multi-component gas drive front and its evolution law. Multi-component gases include N2, CO2, CH4 and other components. Due to the differences in viscosity, density, mass transfer and diffusion coefficients between different gases, and the significant differences in the interaction ability between different gases and crude oil, compared with pure CO2 drive, its front and its migration have multi-component difference distribution characteristics, resulting in more complex oil and gas distribution in the gas phase affected area, which cannot be simply evaluated using indicators such as MMP, miscibility, and oil-gas interfacial tension. In short, the multi-component characteristics of multi-component gases greatly increase the difficulty of identifying the gas drive front and make its front evolution law more complicated. Summary of the invention

[0005] In view of this, the present invention provides a method for characterizing a multi-component front of a multi-element gas drive and its evolution law to solve the above problems.

[0006] The present invention provides a method for characterizing a multi-component gas-driven multi-component front and its evolution law, comprising: establishing a multi-component gas-driven multi-component reservoir mechanism model according to the geological parameters of the research block; performing a multi-component gas-driven reservoir numerical simulation based on the multi-component gas-driven multi-component reservoir mechanism model to obtain a numerical simulation result; before the front of each component advances to a production well, dividing the front of each component based on the numerical simulation result, and drawing a visualized front advancement line according to the front of each component; distinguishing the oil phase, the gas phase and the distribution law of each component along the way according to the numerical simulation result and the visualized front advancement line. Domain division is performed to obtain the regional distribution results of each component; the injection volume step or time step is determined according to the numerical simulation results, the visualized front advancement line and the regional distribution results of each component, and the saturation and content data of each component on the mainstream line are extracted once every injection volume step or time step until all component fronts advance to the production wells, and the relationship between the distance between the injection and production wells and the injection volume or injection time of the front of each component is plotted; the spatiotemporal evolution law of the front of each component is quantitatively characterized according to the variation relationship, different production stages of multi-element gas drive are divided, and the duration of different production stages is determined.

[0007] In another implementation of the present invention, the geological parameters include reservoir porosity, reservoir permeability, reservoir heterogeneity, reservoir temperature, and reservoir pressure.

[0008] In another implementation of the present invention, before the front of each component advances to the production well, the front of each component is divided based on the numerical simulation results, and a visual front advancement line is drawn according to the front of each component, including: before the front of each component advances to the production well, the oil phase and gas phase saturation distribution profile, and the distribution profile of each component of the oil phase and the gas phase at a certain injection amount or a certain time are selected from the numerical simulation results; according to the characteristics of the profile, the front of each component is divided into component sweep fronts, and the fronts include a carbon-rich front, an effective component front, an N2-rich front, a CO2-rich front and a gas segment plug front; according to the front of each component, a visual front advancement line is drawn on the saturation profile diagram.

[0009] In another implementation of the present invention, the distribution law of the oil phase, gas phase and their components along the way is divided into regions according to the numerical simulation results and the visualized front advancement line to obtain the regional distribution results of each component, including: before the front of each component advances to the production well, selecting the oil phase and gas phase saturation and the molar content data of each component of the oil phase and gas phase on the mainstream line between the injection well and the production well at a certain injection volume or a certain time from the numerical simulation results; plotting the relationship between the oil phase and gas phase saturation and the content of each component of the oil phase and gas phase on the mainstream line and the distance between the injection and production wells; determining the distribution law of the oil phase, gas phase and their components along the way according to the change curve; dividing the distribution law along the way according to the visualized front advancement line to obtain the regional distribution results of each component.

[0010] In another implementation of the present invention, the regional distribution results of each component include the original oil zone, the oil phase transition zone, the gas-rich transition zone, the gas-rich zone, the N2 immiscible zone, the CO2 immiscible zone and the multi-gas slug zone.

[0011] In another implementation of the present invention, it further includes: defining a dimensionless distance according to the distance between the injection and production wells:

[0012] L D =L Component / L Well

[0013] Among them, L D is dimensionless distance, dimensionless; L Component is the migration distance of components on the mainstream line, m; L Well is the distance between injection and production wells, m; when L D = 0, it means that each component is at the bottom of the injection well; when L D When =1, it means that each component migrates to the bottom of the production well.

[0014] In another implementation of the present invention, the production stage includes the original oil production stage, the solution gas production stage, the gas-rich transition stage, the gas-rich drive stage, the N2 immiscible drive stage, the CO2 immiscible drive stage and the multi-gas segment plug drive stage.

[0015] The method for characterizing multi-component fronts of multi-element gas drive and their evolution laws of the present invention, based on the establishment of a multi-element gas drive reservoir mechanism model and the output of its simulation results, visualizes and identifies the fronts of each component of the multi-element gas drive as a component sweep front, a carbon-rich front, an effective component front, an N2-rich front, a CO2-rich front and a gas segment plug front, quantitatively characterizes the spatiotemporal evolution laws of the above-mentioned fronts within the reservoir scale, and can achieve accurate prediction of multi-component front breakthroughs; at the same time, the multi-element gas drive is divided into multiple production stages, including the original oil production stage, the dissolved gas production stage, the gas-rich transition stage, the gas-rich drive stage, the N2 non-miscible drive stage, the CO2 non-miscible drive stage and the multi-element gas segment plug drive stage, and quantitatively characterizes the duration of different production stages, which can provide a basis for subsequent residual oil potential tapping and reasonable adjustment and expansion of sweep technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. By reading the detailed description of the following implementations, the advantages and benefits of the solutions become clear to those skilled in the art. The drawings are only used to illustrate the preferred implementations and are not to be considered as limiting the present invention.

[0017] In the attached picture:

[0018] Figure 1 The figure is a flow chart of a method for characterizing a multi-component front of a multi-gas drive and its evolution law according to an embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram of a multi-component reservoir mechanism model of a multi-gas drive according to an embodiment of the present invention.

[0020] Figure 3 This is a schematic diagram of the division of the multi-component front advancement line of the multi-gas drive according to an embodiment of the present invention.

[0021] Figure 4 This is a relationship curve between the multi-gas flooding oil phase and its components and the dimensionless distance according to an embodiment of the present invention.

[0022] Figure 5 This is a relationship curve between the multi-gas drive gas phase and its components and the dimensionless distance according to an embodiment of the present invention.

[0023] Figure 6 This is a time-space evolution relationship curve of a multi-component front of a multi-element gas drive according to an embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be described clearly and in detail below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in the field based on the embodiments in the embodiments of the present invention should fall within the scope of protection of the embodiments of the present invention.

[0025] Figure 1 A flow chart of a method for characterizing a multi-component gas flooding front and its evolution law provided in an embodiment of the present invention is shown in FIG. Figure 1 As shown, this embodiment mainly includes:

[0026] S101. Based on the geological parameters of the study area, a multi-component gas-driven reservoir mechanism model is established.

[0027] Preferably, a typical mechanism model of multi-element gas drive considering the geological factors of the study block is established: based on the geological conditions such as porosity, permeability and heterogeneity of the oil reservoir in the study block, the geological parameters that have a greater impact on the front distribution and migration are set, including reservoir porosity, reservoir permeability, reservoir heterogeneity, reservoir temperature, reservoir pressure, etc.; by changing the above factors, a typical mechanism model of multi-element gas drive for different types of reservoirs such as tight, (ultra / ultra) low permeability, medium and high permeability can be established.

[0028] Preferably, a reservoir fluid model considering the multi-component characteristics of multiple gases is established: based on the well flow composition of the study block or the results of indoor PVT analysis and testing, the component composition of the formation oil in the study block and the high-temperature and high-pressure physical properties of the formation oil, such as saturation pressure, dissolved gas-oil ratio, viscosity, and density, are obtained; considering the multi-component characteristics of multiple gases such as N2, CO2, and CH4, the pseudo-components of the reservoir fluid set should include N2, CO2, and C1 components; other pseudo-components can be set as C2-C4, C5-C6, and C 7+ , C 15+ Etc., and can be appropriately adjusted according to the composition of the formation oil in the study area; the set pseudo-components are fitted with the high-temperature and high-pressure physical property parameters (PVT), and when the fitting accuracy exceeds 95%, the reservoir fluid model can be output as a multi-element gas drive.

[0029] Preferably, a reservoir development model is established considering the well layout and multi-gas injection parameters: according to the reservoir development characteristics of the study area, the model can be set to one of the five-point method, the positive (negative) seven-point method, the diamond positive (negative) seven-point method, the positive (negative) nine-point method, or the model can be set to 1 / 4 well network of one of the above well layout methods; the distance between the injection well and the production well can be set to one of 200m, 300m, 400m, 500m, etc.; the proportions of N2, CO2, CH4 and other components in the multi-gas are reasonably adjusted, and the injection rate, injection volume and other parameters of the multi-gas are reasonably set to meet the development needs of different types of reservoirs such as dense, (ultra / extra) low permeability, medium and high permeability.

[0030] like Figure 2 As shown, the main characteristic parameters used in the multi-component gas drive multi-component reservoir mechanism model of the present invention include:

[0031] Typical geological parameters: reservoir porosity 13.78%, reservoir permeability 8.77×10 -3 μm 2 , Lorentz coefficient (heterogeneity) 0.35, reservoir temperature 65°C, reservoir pressure 24.99MPa.

[0032] Reservoir fluid parameters: pseudo components are CO2, N2, C1, C2-C4, C5-C6, C 7+ , C 15+ The molar contents are 2.46%, 0.57%, 36.37%, 9.45%, 3.19%, 19.66% and 28.30% respectively; the formation oil viscosity is 2.73mPa·s and the formation oil density is 772kg / m 3 , original solution gas-oil ratio 43.73m 3 / t, original oil saturation 0.63.

[0033] Model development parameters: five-point method 1 / 4 well pattern, injection-production well spacing of 300m; multi-component gas is N2+CO2+CH4, with molar contents of 0.69, 0.28 and 0.03 respectively; multi-component gas injection rate is 0.02PV / a.

[0034] S102. Perform numerical simulation of a multi-component gas drive reservoir based on a multi-component gas drive multi-component reservoir mechanism model to obtain numerical simulation results.

[0035] Exemplarily, the established multi-component gas drive multi-component reservoir mechanism model is used to carry out simulation work on improving oil recovery by multi-component gas drive. The simulated injection volume can be set to one of 0.2PV to 1.2PV (or the simulation time can be set to one of 10 to 30 years), but it is necessary to ensure that the fronts of all components in the multi-component gas are advanced to the bottom of the production well; the oil (gas) saturation and its profile distribution, the molar content of each oil (gas) component and its profile distribution during the multi-component gas drive process and other data are obtained.

[0036] In the present invention, taking the setting of simulation time as 30 years and the total injection volume of multi-gas as 0.60PV as an example, after the simulation, the oil (gas) phase saturation profile, the distribution profile of each component of the oil (gas) phase, the content data of the oil (gas) phase and its components in the mainstream line between the injection and production wells, the stage recovery degree data, etc. under different injection volume (or injection time) conditions are obtained.

[0037] S103. Before the front of each component advances to the production well, the front of each component is divided based on the numerical simulation results, and a visual front advancement line is drawn according to the front of each component.

[0038] S104. According to the numerical simulation results and the visualized front advancement line, the distribution patterns of the oil phase, gas phase and each component along the way are divided into regions to obtain the regional distribution results of each component.

[0039] S105. Determine the injection volume step or time step based on the numerical simulation results, the visualized front advancement line and the regional distribution results of each component. Extract the saturation and content data of each component on the mainstream line once every injection volume step or time step until all component fronts advance to the production wells. Draw the relationship between the distance between the fronts of each component along the injection and production wells and the injection volume or injection time.

[0040] S106. Quantify and characterize the temporal and spatial evolution law of the front of each component according to the change relationship, divide the different production stages of multi-gas drive, and determine the duration of different production stages.

[0041] The method for characterizing multi-component fronts of multi-element gas drive and their evolution laws of the present invention, based on the establishment of a multi-element gas drive reservoir mechanism model and the output of its simulation results, visualizes and identifies the fronts of each component of the multi-element gas drive as a component sweep front, a carbon-rich front, an effective component front, an N2-rich front, a CO2-rich front and a gas segment plug front, quantitatively characterizes the spatiotemporal evolution laws of the above-mentioned fronts within the reservoir scale, and can achieve accurate prediction of multi-component front breakthroughs; at the same time, the multi-element gas drive is divided into multiple production stages, including the original oil production stage, the dissolved gas production stage, the gas-rich transition stage, the gas-rich drive stage, the N2 non-miscible drive stage, the CO2 non-miscible drive stage and the multi-element gas segment plug drive stage, and quantitatively characterizes the duration of different production stages, which can provide a basis for subsequent residual oil potential tapping and reasonable adjustment and expansion of sweep technology.

[0042] In another implementation of the present invention, the geological parameters include reservoir porosity, reservoir permeability, reservoir heterogeneity, reservoir temperature, and reservoir pressure.

[0043] In another implementation of the present invention, before the front of each component advances to the production well, the front of each component is divided based on the numerical simulation results, and a visual front advancement line is drawn according to the front of each component, including: before the front of each component advances to the production well, the oil phase and gas phase saturation distribution profile, and the distribution profile of each component of the oil phase and the gas phase at a certain injection amount or a certain time are selected from the numerical simulation results; according to the characteristics of the profile, the front of each component is divided into component sweep fronts, and the fronts include a carbon-rich front, an effective component front, an N2-rich front, a CO2-rich front and a gas segment plug front; according to the front of each component, a visual front advancement line is drawn on the saturation profile diagram.

[0044] Exemplarily, based on the numerical simulation results of the multi-component gas drive reservoir, before all the component fronts migrate to the production wells, the oil (gas) saturation distribution profile and the oil (gas) component distribution profile under a certain injection volume (or a certain time) are selected, and the multi-component gas drive front is divided into component sweep front, carbon-rich front, effective component front, N2-rich front, CO2-rich front and gas segment plug front according to the above profile characteristics. The multi-component gas drive front advancement line is drawn on the saturation profile diagram, and the significant characteristics of each component front are described.

[0045] Component sweep front: Select the distribution profile of the molar content (decimal, the same below) of the oil phase C1 component, and determine the point where the oil phase C1 begins to increase as the component sweep front; the significant feature of the component sweep front is that the oil phase C1 begins to increase, and the oil saturation S o Increases slightly to the maximum value, the gas phase has not yet been affected, and the gas saturation S g =0; in the oil saturation profile, S o By connecting the maximum points of , we can draw the component wave and front edge advancement line.

[0046] Carbon-rich front: Select the molar content distribution profile of the oil phase C1 component and the gas phase C1 component, and determine the maximum point of the oil phase C1 and the gas phase C1 as the carbon-rich front; the significant characteristics of the carbon-rich front are that both the oil phase C1 and the gas phase C1 reach the maximum value, and the gas saturation increase value ΔS g ≈0.1, oil saturation reduction value ΔS o ≈0.1; in the oil saturation profile, ΔS o The carbon-rich front advancement line can be drawn by connecting the saturation points with a value of ≈0.1 into a line.

[0047] Effective component front: Select the molar content distribution profile of the oil phase C2-C4 component, and determine the point where the oil phase C2-C4 decreases by more than 10% as the effective component front; the significant characteristics of the effective component front are that the oil phase C2-C4 begins to decrease significantly (the decrease is more than 10%), the gas phase C2-C4 is about 90% of the maximum concentration and begins to gradually decrease, and the gas saturation increase value ΔS g ≈0.25, oil saturation reduction value ΔS o ≈0.25; in the oil saturation profile, ΔS o The saturation points of ≈0.25 are connected into a line to draw the effective component front advancement line.

[0048] N2-rich front: Select the molar content distribution profile of the gas phase N2 component and determine the maximum point of the gas phase N2 component as the N2-rich front; the significant characteristics of the N2-rich front are that the gas phase N2 component reaches the maximum value, the oil phase C5-C6 component begins to decrease significantly (the decrease is more than 10%), and the gas saturation increase value ΔS g ≈0.30, oil saturation reduction value ΔS o ≈0.30; in the oil saturation profile, ΔS o By connecting the saturation points of ≈0.30 into a line, the N2-rich front advancement line can be drawn.

[0049] CO2-rich front: Select the molar content distribution profile of the gas phase CO2 component, and determine the inflection point of the increase of the gas phase CO2 component (molar content is about 80% of the injected concentration) as the CO2-rich front; the significant feature of the CO2-rich front is that the gas phase CO2 increases rapidly to about 80% of the injected CO2 concentration and then slows down. 7+ It begins to decrease significantly (the decrease exceeds 10%), and the gas saturation increases by ΔS g ≈0.35-0.40, oil saturation reduction value ΔS o ≈0.35-0.40; In the oil saturation profile, ΔS o The saturation points of ≈0.35-0.40 are connected into a line to draw the CO2-rich front advancement line.

[0050] Gas slug front edge: Select gas phase C 5+ The molar content distribution profile of the components is shown in Figure 2. 5+ The point where the drop exceeds 75% is determined as the front edge of the gas slug. The prominent feature of the front edge of the gas slug is the gas phase C 5+ The gas phase is mainly composed of the N2+CO2+CH4 multi-gas plug injected initially, and the oil phase C 7+ It is only about 15% of the initial concentration, and the gas saturation S g ≈0.45, oil saturation reduction value ΔSo ≈0.45; in the oil saturation profile, ΔS o By connecting the saturation points of ≈0.45, the advancement line of the leading edge of the gas segment plug can be drawn.

[0051] The relative positions of the fronts of each component of multi-element gas drive, along the direction from the production well to the injection well, are: ① component sweep front, ② carbon-rich front, ③ effective component front, ④ N2-rich front, ⑤ CO2-rich front, ⑥ gas slug front.

[0052] like Figure 3 As shown, the present invention takes the analysis of the oil (gas) phase saturation profile and the distribution profile of each component of the oil (gas) phase under the condition of a total multi-gas injection volume of 0.04PV (2 years) as an example, and divides the component sweep front, carbon-rich front, effective component front, N2-rich front, CO2-rich front and gas slug front into:

[0053] Component wave front: located at L D = 0.79, the molar content of oil phase C1 begins to increase, and the oil saturation S o Increases slightly to the maximum value, the gas phase has not yet been affected, and the gas saturation S g =0.

[0054] Carbon-rich front: located at L D = 0.74, the molar content of oil phase C1 and gas phase C1 reaches the maximum value, and the gas saturation increases by ΔS g =0.11, oil saturation reduction value ΔS o =0.11.

[0055] Effective component front edge: located at L D =0.71, the molar content of oil phase C2-C4 began to decrease significantly, with a decrease of 10.34%, and the gas phase C2-C4 was about 86.29% of the highest concentration, and the gas saturation increased by ΔS g =0.26, oil saturation reduction value ΔS o =0.26.

[0056] N2-rich front: located at L D =0.62, the gas phase N2 molar content reaches a maximum value (mol fraction = 0.72), the oil phase C5-C6 components begin to decrease significantly, the decrease reaches 14.67%, and the gas saturation increase value ΔS g =0.30, oil saturation reduction value ΔS o =0.30.

[0057] CO2-rich front: located at L D= 0.45, the gas phase CO2 component inflection point, the molar content is about 79.78% of the injection concentration, the oil phase C 7+ The gas saturation increased by ΔS g ≈0.38, oil saturation reduction value ΔS o ≈0.38.

[0058] Air slug front edge: located at L D =0.21, gas phase C 5+ The oil phase C 7+ It is only 14.49% of the initial concentration. The gas components are mainly N2+CO2+CH4 multi-gas slugs. The gas saturation increase value ΔS g =0.46, oil saturation reduction value ΔS o =0.46.

[0059] In another implementation of the present invention, the distribution law of the oil phase, gas phase and their components along the way is divided into regions according to the numerical simulation results and the visualized front advancement line to obtain the regional distribution results of each component, including: before the front of each component advances to the production well, selecting the oil phase and gas phase saturation and the molar content data of each component of the oil phase and gas phase on the mainstream line between the injection well and the production well at a certain injection volume or a certain time from the numerical simulation results; plotting the relationship between the oil phase and gas phase saturation and the content of each component of the oil phase and gas phase on the mainstream line and the distance between the injection and production wells; determining the distribution law of the oil phase, gas phase and their components along the way according to the change curve; dividing the distribution law along the way according to the visualized front advancement line to obtain the regional distribution results of each component.

[0060] For example, due to the different development methods of different types of oil reservoirs, the distance between the injection well and the production well may be 200m, 300m, 400m, 500m, etc. In order to make the present invention universal, a dimensionless distance is defined.

[0061] Extract the saturation data and molar content data of each component on the mainstream line of a certain injection volume or (a certain time), where the saturation data includes the oil saturation S o and gas saturation S g , oil phase component data include N2, CO2, C1, C2-C4, C5-C6, C 7+ The molar content of the gas phase components includes N2, CO2, C1, C2-C4, C5-C6, C 7+ Equal molar contents, such as Figure 4 and Figure 5As shown, the relationship curves of oil saturation, each component of the oil phase and the dimensionless distance, and the relationship curves of gas saturation, each component of the gas phase and the dimensionless distance are plotted respectively.

[0062] According to the description of the multi-component front characteristics, on Figure 4 and Figure 5 the position points of the fronts of each component are marked on the two relationship curves, specifically: the position point of the component swept front is L D = a (0 < a < 1); the position point of the carbon-rich front is L D = b (0 < b < a); the position point of the effective component front is L D = c (0 < c < b); the position point of the N2-rich front is L D = d (0 < d < c); the position point of the CO2-rich front is L D = e (0 < e < d); the position point of the gas slug front is L D = f (0 < f < e).

[0063] In another implementation manner of the present invention, the regional distribution results of each component include the original oil area, the oil-phase transition area, the gas-rich transition area, the gas-rich area, the N2 immiscible area, the CO2 immiscible area, and the multi-component gas slug area.

[0064] Exemplarily, according to the description of the multi-component front characteristics and the position of the front of each component, the along-flow distribution area of the oil (gas) phase is divided into the original oil area, the oil-phase transition area, the gas-rich transition area, the gas-rich area, the N2 immiscible area, the CO2 immiscible area, and the multi-component gas slug area. Specifically:

[0065] Original oil area: The range between the component swept front and the production well is divided into the original oil area, a < L D ≤ 1, and its significant feature is that the gas phase has not yet swept (S g = 0), and the oil phase maintains the original formation oil saturation state (S o = S oi ).

[0066] Oil-phase transition area: The range between the carbon-rich front and the component swept front is divided into the oil-phase transition area, b < L D ≤ a, and its significant feature is that the gas phase still has not swept (S g = 0), but the C1 component in the gas phase dissolves in the oil phase by means of mass transfer, diffusion, etc., resulting in a slight increase in the C1 component in the oil phase, and a slight decrease in C2-C4, C5-C6 and C 7+ in the oil phase. The components and composition of the formation oil have changed, and the oil saturation has increased slightly.

[0067] Gas-rich transition area: The range between the effective component front and the carbon-rich front is divided into the gas-rich transition area, c < L D≤b, its notable feature is that the C1 component in the injected multi-component gas has spread to C1, C2-C4, C5-C6, C 7+ Different components such as carbon dioxide and carbon dioxide exchange rapidly in the oil phase and the gas phase, the oil saturation decreases rapidly, and the gas saturation increases rapidly.

[0068] Gas-rich zone: The area between the N2-rich front and the effective component front is divided into the gas-rich zone, d<L D ≤c, its notable feature is that the gas phase is rich in C2-C4, C 5+ The C1 and C2-C4 components in the oil phase were significantly reduced, and the C5-C6 and C 7+ The content remains almost unchanged. The injected gas mainly extracts the light hydrocarbon components in the formation oil. The oil saturation decreases significantly, while the gas saturation continues to increase.

[0069] N2 immiscible zone: The range between the CO2-rich front and the N2-rich front is divided into the N2 immiscible zone, e<L D ≤d, its notable characteristics are that the gas phase N2 reaches a maximum value and then begins to decrease slightly, the C5-C6 components in the oil phase decrease significantly, and C 7+ The content remains almost unchanged, and the injected N2 gas mainly extracts the C5-C6 intermediate hydrocarbon components in the formation oil.

[0070] CO2 immiscible zone: The area between the front edge of the gas slug and the front edge of the CO2-rich gas is divided into the CO2 immiscible zone, f<L D ≤e, its notable feature is that the gas phase CO2 content reaches about 80% of the initial injection concentration, and the C 7+ The components are significantly reduced, and the injected CO2 gas mainly extracts C 7+ Heavy hydrocarbon components.

[0071] Multi-element gas slug area: The area between the injection well and the front edge of the gas slug is divided into the multi-element gas slug area, 0<L D ≤f, its notable features are that the contents of N2, CO2 and CH4 in the gas phase gradually transition to the designed contents of each component of the multi-gas, and the gas phase C2-C4 and C 5+ It gradually approaches 0, that is, there is a multi-gas transition zone. After the transition zone, the gas phase components almost no longer have mass transfer exchange with the oil phase, and the multi-gas cannot play an oil displacement role, forming a residual oil zone.

[0072] like Figure 4 and Figure 5As shown, in the present invention, the oil (gas) saturation and the molar content of each component of oil (gas) under the condition of extracting the total injection volume of multi-gas 0.04PV (2 years) are taken as an example, and the relationship between the oil (gas) saturation and the content of each component of oil (gas) on the mainstream line and the dimensionless well spacing is plotted, and the distribution of oil (gas) along the production well to the injection well is determined to be the original oil zone, oil phase transition zone, gas-rich transition zone, gas-rich zone, N2 immiscible zone, CO2 immiscible zone and multi-gas slug zone, specifically:

[0073] Original oil zone: located between the component sweep front and the production well (0.79<L D ≤1), the gas phase has not yet reached (S g =0), the oil phase is maintained at the original formation oil saturation state (S o =S oi ).

[0074] Oil phase transition zone: located between the carbon-rich front component and the front (0.74<L D ≤0.79), the gas phase is still not affected (S g =0), but the C1 component in the gas phase has dissolved in the oil phase, the components and composition of the formation oil have changed, and the oil saturation has increased slightly.

[0075] Gas-rich transition zone: located between the effective component front and the carbon-rich front (0.71<L D ≤0.74), the C1 component in the injected multi-component gas has been affected, C1, C2-C4, C5-C6, C 7+ Different components such as carbon dioxide and carbon dioxide exchange rapidly in the oil phase and the gas phase, the oil saturation decreases rapidly, and the gas saturation increases rapidly.

[0076] Gas-rich zone: located between the effective component fronts of the rich N2 front (0.62<L D ≤0.71), the gas phase is rich in C2-C4, C 5+ The injected gas mainly extracts the light hydrocarbon components in the formation oil. The C1 and C2-C4 components in the oil phase are significantly reduced, the oil saturation decreases significantly, and the gas saturation continues to rise.

[0077] N2 immiscible zone: located between the CO2-rich front and the N2-rich front (0.45<L D ≤0.61), the gas phase N2 reaches a maximum value, the C5-C6 components in the oil phase are significantly reduced, and the injected N2 gas mainly extracts the C5-C6 intermediate hydrocarbon components in the formation oil.

[0078] CO2 immiscible zone: located between the front edge of the gas slug and the CO2-rich front edge (0.21<L D ≤0.45), the gas phase CO2 content reaches about 80% of the initial injection concentration, and the oil phase C 7+The components are significantly reduced, and the injected CO2 gas mainly extracts C 7+ Heavy hydrocarbon components.

[0079] Multi-gas slug area: located between the front edges of the gas slugs in the injection well (0<L D ≤0.21), the contents of N2, CO2 and CH4 in the gas phase gradually transition to the designed contents of each component of the multi-gas, and the gas phase C2-C4 and C 5+ It gradually approaches 0. After the transition zone, the gas phase components almost no longer have mass transfer exchange with the oil phase. The multi-component gas cannot play an oil displacement role, forming a residual oil zone.

[0080] In another implementation of the present invention, it further includes: defining a dimensionless distance according to the distance between the injection and production wells:

[0081] L D =L Component / L Well

[0082] Among them, L D is dimensionless distance, dimensionless; L Component is the migration distance of components on the mainstream line, m; L Well is the distance between injection and production wells, m; when L D = 0, it means that each component is at the bottom of the injection well; when L D When =1, it means that each component migrates to the bottom of the production well.

[0083] In another implementation of the present invention, the production stage includes the original oil production stage, the solution gas production stage, the gas-rich transition stage, the gas-rich drive stage, the N2 immiscible drive stage, the CO2 immiscible drive stage and the multi-gas segment plug drive stage.

[0084] For example, the temporal and spatial evolution relationship of multi-component fronts in multi-component gas flooding refers to the distribution and migration law of each front along the main flow line (space) between injection and production wells under different injection volumes or injection times (time). The required parameters include the dimensionless distance L D and the multi-gas injection volume (V g-RC ) or the multi-gas injection time (t). When the multi-gas injection rate is constant, due to the injection volume (V g-RC ) has the following relationship with the injection time t:

[0085] V g-RC =v RC / t

[0086] Among them, V g-RC is the injection volume of multi-component gas under reservoir conditions, PV; v RC is the injection rate of multi-component gas under reservoir conditions, PV / a; t is the multi-component gas injection time, a.

[0087] That is, the amount of multi-element gas injected V g-RC is linearly related to the injection time t, so L D -V g-RC Relationship curve and L D -t relationship curves can be used to characterize the spatiotemporal evolution characteristics of multi-component fronts of multi-component gas flooding.

[0088] The data required to characterize the spatiotemporal evolution of the multi-component front include: setting the initial injection volume V of the multi-component gas g-RC | i＝0 =0 (or initial time t| i＝0 =0), set the injection volume step to ΔV g-RC (or set the time step to Δt), each increase of ΔV g-RC The injection volume (or each additional Δt time) is to extract the oil (gas) saturation and oil (gas) component content data on the mainstream line in the simulation results once, until all component fronts are advanced to the production well, and the extraction is n times in total. The injection volume or injection time of the multi-component gas at any time i is:

[0089] V g-RC | i =V g-RC | i-1 +ΔV g-RC (i=1,2,3,……,n)

[0090] or t| i =t+Δt(i=1,2,3,……,n)

[0091] According to the injection volume V at any time i g-RC | i (or injection time t| i ) The oil (gas) saturation of the main flow line and the content of each component of oil (gas) are used to determine the dimensionless distance L of the front edge of each component. D | i , repeat the analysis n times in total, and then we can get the time and space sequence points (V g-RC | i , L D | i ) or (t| i , L D | i ), specifically:

[0092] ① Component wave front time and space sequence points: (V g-RC① |0,L D① |0=0)、(V g-RC① |1,L D① |1) ,……,

[0093] (V g-RC① | i , L D① | i ),……,(V g-RC① | n1 , L D① | n1 =1) or (t ① |0,L D① |0=0)、(t ① |2, L D① |2)、……、(t ① | i , L D① | i ),……,(t ① | n1 , L D① | n1 =1)

[0094] ② Carbon-rich front time and space sequence points: (V g-RC② |0,L D② |0=0)、(V g-RC② |1,L D② |1) ,……,

[0095] (V g-RC② | i , L D② | i ),……,(V g-RC② | n2 , L D② | n2 =1) or (t ② |0,L D② |0=0)、(t ② |1,L D② |1)、……、(t ② | i , L D② | i ),……,(t ② | n2 , L D② | n2 =1)

[0096] ③ Effective component front time and space sequence point: (V g-RC③ |0,L D③ |0=0)、(V g-RC③ |1,L D③ |1) ,……,

[0097] (V g-RC③ | i , L D③ | i),……,(V g-RC③ | n3 , L D③ | n3 =1) or (t ③ |0,L D③ |0=0)、(t ③ |1,L D③ |1)、……、(t ③ | i , L D③ | i ),……,(t ③ | n3 , L D③ | n3 =1)

[0098] ④ N2-rich front time and space sequence points: (V g-RC④ |0,L D④ |0=0)、(V g-RC④ |1,L D④ |1) ,……,

[0099] (V g-RC④ | i , L D④ | i ),……,(V g-RC④ | n4 , L D④ | n ) or (t ④ |0,L D④ |0=0)、(t ④ |1,L D④ |1)、……、(t ④ | i , L D④ | i ),……,(t ④ | n4 , L D④ | n4 =1)

[0100] ⑤ Space-time sequence points of CO2-rich front: (V g-RC⑤ |0,L D⑤ |0=0)、(V g-RC⑤ |1,L D⑤ |1) ,……,

[0101] (V g-RC⑤ | i , L D⑤ | i ),……,(V g-RC⑤ | n5 , L D⑤ | n5=1) or (t ⑤ |0,L D⑤ |0)、(t ⑤ |1,L D⑤ |1)、……、(t ⑤ | i , L D⑤ | i ),……,(t ⑤ | n5 , L D⑤ | n5 =1)

[0102] ⑥ Space-time sequence points of the front edge of the gas slug: (V g-RC⑥ |0,L D⑥ |0=0)、(V g-RC⑥ |1,L D⑥ |1) ,……,

[0103] (V g-RC⑥ | i , L D⑥ | i ),……,(V g-RC⑥ | n6 , L D⑥ | n6 =1) or (t ⑥ |0,L D⑥ |0=0)、(t ⑥ |1,L D⑥ |1)、……、(t ⑥ | i , L D⑥ | i ),……,(t ⑥ | n6 , L D⑥ | n6 =1)

[0104] It should be understood that the above subscripts ①, ②, ③, ④, ⑤, ⑥ represent the component sweep front, carbon-rich front, effective component front, N2-rich front, CO2-rich front and gas slug front respectively; subscript n1 <n2<n3<n4<n5<n6。

[0105] Preferably, the time-space sequence points of each component are connected into a line to obtain the time-space evolution relationship line of each leading edge, that is, L D -V g-RC Relationship curve (or L D -t relationship curve), the temporal and spatial evolution relationship curves of the leading edges of each component have typical three-stage characteristics, specifically:

[0106] Early nonlinear section: Affected by the vicinity of the injection well, each front edge is in L DThe early nonlinear seepage stage is shown in the range of ≈0 to 0.2, and the advancement speed of each front increases with the increase of injection volume (or time).

[0107] Mid-term quasi-linear segment: In the deep reservoir L D In the range of ≈0.2 to 0.8, the advancing speed of each front is stable, showing a medium-term quasi-linear seepage.

[0108] Late nonlinear stage: Affected by the vicinity of the production well, each front is in L D The late nonlinear seepage stage is present in the range of ≈0.8~1, among which the advancement speeds of the component sweep front, carbon-rich front and effective component front are accelerated, while the advancement speeds of the N2-rich front, CO2-rich front and gas segment plug front are slowed down.

[0109] Preferably, according to L D -V g-RC Relationship curve (or L D -t relationship curve), when L D = 1, the front advances to the production well, and the multi-gas injection volume (or injection time) at this time is the front breakthrough time; According to this method, the breakthrough time of the component sweep front, carbon-rich front, effective component front, N2-rich front, CO2-rich front, and gas segment plug front can be determined as V g-RC① | n1 、V g-RC② | n2 、V g-RC③ | n3 、V g-RC④ | n4 、V g-RC⑤ | n5 、V g-RC⑥ | n6 (or t ① | n1 ,t ② | n2 ,t ③ | n3 ,t ④ | n4 ,t ⑤ | n5 ,t ⑥ | n6 ).

[0110] According to the breakthrough moment of each component front, the development stage of multi-gas drive can be divided into the original oil production stage, solution gas production stage, gas-rich transition stage, gas-rich drive stage, N2 immiscible drive stage, CO2 immiscible drive stage and multi-gas segment plug drive stage. Specifically:

[0111] Initial oil production stage: The initial oil production stage is from the beginning of multi-component gas injection to the breakthrough of the component sweep front. During this stage, the initial oil zone gradually advances from the injection well to the production well, and the duration is injection volume 0~V g-RC① | n1 (or injection time 0~t ① | n1 ).

[0112] Solution gas production stage: The period from the breakthrough of the component sweep front to the breakthrough of the carbon-rich front is the solution gas production stage. During this stage, the oil phase transition zone gradually advances from the injection well to the production well, and the duration is the injection volume V g-RC① | n1 ~V g-RC② | n2 (or injection time t ① | n1 ~t ② | n2 ).

[0113] Gas-rich transition section: The gas-rich transition section is from the breakthrough of the carbon-rich front to the breakthrough of the effective component front. In this stage, the gas-rich transition zone gradually advances from the injection well to the production well, and the duration is the injection volume V g-RC② | n2 ~V g-RC③ | n3 (or injection time t ② | n2 ~t ③ | n3 ).

[0114] Gas-rich drive stage: From the breakthrough of the effective component front to the breakthrough of the rich N2 front, the gas-rich drive stage is the stage in which the gas-rich zone gradually advances from the injection well to the production well, and the duration is the injection volume V g-RC③ | n3 ~V g-RC④ | n4 (or injection time t ③ | n3 ~t ④ | n4 ).

[0115] N2 immiscible flooding stage: After the breakthrough of the rich N2 front until the breakthrough of the rich CO2 front is the N2 immiscible flooding stage. In this stage, the N2 immiscible zone gradually advances from the injection well to the production well, and the duration is the injection volume V g-RC④ | n4 ~V g-RC⑤ | n5 (or injection time t ④ | n4 ~t ⑤ | n5 ).

[0116] CO2 immiscible flooding stage: The CO2 immiscible flooding stage is from the breakthrough of the CO2-rich front to the breakthrough of the gas slug front. In this stage, the CO2 immiscible zone gradually advances from the injection well to the production well, and the duration is the injection volume V g-RC⑤ | n5 ~V g-RC⑥ | n6 (or injection time t ⑤ | n5 ~t ⑥ | n6 ).

[0117] Multi-element gas slug drive stage: After the gas slug front breaks through until the end of the simulation, it is the multi-element gas slug drive stage. In this stage, the multi-element gas slug area gradually advances from the injection well to the production well, and the duration is injection volume ≥ V g-RC⑥ | n6 (or injection time ≥ t ⑥ | n6 ).

[0118] like Figure 6 As shown in the figure, in the present invention, taking the injection volume step size of 0.001667PV (or the time step size of 1 month) as an example, the oil (gas) saturation and the content data of each component of oil (gas) on the mainstream line are extracted once at each step size until all component fronts advance to the production well, and the dimensionless relationship curve of the front of each component with the injection volume (or injection time) is drawn (L D -V g-RC Relationship curve or L D -t relationship curve) to analyze the temporal and spatial evolution of each component front, determine the different production stages of multi-element gas drive, and give the duration of different stages. Specifically:

[0119] The breakthrough order of the component fronts is component sweep front, carbon-rich front, effective component front, N2-rich front, CO2-rich front and gas segment plug front.

[0120] The three-stage characteristics of the spatiotemporal evolution: ① Affected by the vicinity of the injection well, each front is D = 0~0.2, all of them present the early nonlinear seepage stage, and the advancing speed of each front increases with the increase of injection volume (or time); ② In the deep reservoir L D = 0.2 ~ 0.8, the advancement speed of each front is stable, showing a mid-term quasi-linear seepage section; ③ Affected by the vicinity of the production well, each front is in the range of L D = 0.8~1, the late nonlinear seepage stage is presented, in which the advancement speeds of the component sweep front, carbon-rich front and effective component front are accelerated, while the advancement speeds of the N2-rich front, CO2-rich front and gas segment plug front are slowed down.

[0121] The breakthrough time of the front of each component is: the breakthrough time of the component sweep front is 0.0467PV (or 2.33 years), the breakthrough time of the carbon-rich front is 0.0478PV (or 2.39 years), the breakthrough time of the effective component front is 0.0488PV (or 2.44 years), the breakthrough time of the N2-rich front is 0.06PV (or 3 years), the breakthrough time of the CO2-rich front is 0.12PV (or 6 years), and the breakthrough time of the gas segment plug front is 0.295PV (or 14.75 years).

[0122] The duration of different production stages is as follows: the original oil production stage is the time period from the beginning of multi-gas injection to the breakthrough of the component sweep front, which lasts for 0-0.0467PV (or 0-2.33 years); the dissolved gas production stage is the time period from the breakthrough of the component sweep front to the breakthrough of the carbon-rich front, which lasts for 0.0467PV-0.0478PV (or 2.33-2.39 years); the gas-rich transition stage is the time period from the breakthrough of the carbon-rich front to the breakthrough of the effective component front, which lasts for 0.0478PV-0.0488PV (or 2.39-2.44 years); the gas-rich drive stage is the time period from the breakthrough of the effective component front to the breakthrough of the N2-rich front. The period from the breakthrough of the rich N2 front to the breakthrough of the rich CO2 front is 0.0488PV-0.06PV (or 2.44-3 years); the N2 immiscible drive stage is the period from the breakthrough of the rich N2 front to the breakthrough of the rich CO2 front, which lasts 0.06V-0.12PV (or 3-6 years); the CO2 immiscible drive stage is the period from the breakthrough of the rich CO2 front to the breakthrough of the gas slug front, which lasts 0.12V-0.295PV (or 6-14.75 years); the multi-gas slug drive stage is the period from the breakthrough of the gas slug front to the breakthrough of the remaining oil zone, which lasts 0.295V-0.60PV (or 14.75-30 years).

[0123] It should be understood that the characterization method of a multi-component gas drive multi-component front and its evolution law proposed in the present invention can be used to analyze the influence of different factors such as geology, fluid, process, etc. on the characteristics of the multi-component front and its temporal and spatial evolution law when adjusting the geological, fluid and development parameters of the multi-component gas drive multi-component reservoir mechanism model, or adjusting the components of the multi-component gas and their composition, injection rate, injection amount and other process parameters, for example:

[0124] In terms of reservoir geology: when the reservoir permeability increases or the reservoir heterogeneity increases, the component sweep front, carbon-rich front, effective component front, N2-rich front, CO2-rich front and gas segment plug front will all be advanced, the various production stages of multi-gas drive will be greatly shortened, and the effect of multi-gas drive on improving oil recovery will be reduced.

[0125] In terms of reservoir fluid: when the viscosity and density of crude oil increase, the component sweep front, carbon-rich front, effective component front, N2-rich front, CO2-rich front and gas segment plug front will all be advanced, the various production stages of multi-gas drive will be significantly shortened, and the effect of multi-gas drive on improving oil recovery will be reduced.

[0126] In terms of injection technology: when the molar content of CO2 in the multi-gas increases, the component sweep front, carbon-rich front, effective component front, and N2-rich front will be delayed, but the CO2 front and gas slug front will be advanced. The increased CO2 component is conducive to the extraction of C 7+ The effect of multi-gas drive on improving oil recovery is improved.

[0127] Therefore, the characterization method of the multi-component gas drive front and its evolution law proposed in the present invention is used to study the influence of different factors such as geology, fluid, and process on the multi-component front and its temporal and spatial evolution law, which is also within the protection scope of the patent of the present invention.

[0128] In another aspect of the present invention, an electronic device includes: a processor, a memory, a communication bus, and a communication interface.

[0129] in:

[0130] The processor, memory and communication interface communicate with each other through a communication bus.

[0131] Communication interface, used to communicate with other electronic devices or servers.

[0132] The processor is used to execute the program, and specifically can execute the steps of any method for characterizing the multi-component front of multi-gas flooding and its evolution law in the above-mentioned embodiments.

[0133] Specifically, the program may include program codes including computer operation instructions.

[0134] The processor may be a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application. The one or more processors included in the smart device may be processors of the same type, such as one or more CPUs; or processors of different types, such as one or more CPUs and one or more ASICs.

[0135] The memory is used to store programs. The memory may include a high-speed RAM memory, and may also include a non-volatile memory, such as at least one disk memory.

[0136] The program can be specifically used to enable the processor to execute the steps of any of the methods for characterizing a multi-component front of a multi-gas drive and its evolution law described in the embodiments. The specific implementation of each step in the program can refer to the corresponding descriptions in the steps and units executed by any of the methods for characterizing a multi-component front of a multi-gas drive and its evolution law in the above steps, which will not be repeated here. Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working process of the above-described equipment and modules can refer to the corresponding process description in the aforementioned method embodiment.

[0137] The above method according to the embodiment of the present invention can be implemented in a server equipped with a central processing unit CPU and an image processing unit COU.

[0138] Thus far, specific embodiments of the present invention have been described. Other embodiments are within the scope of the appended claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or sequential order shown to achieve the desired results.

[0139] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, back, etc.) are only used to explain the relative position relationship between the components in a certain specific order (as shown in the accompanying drawings). If the specific order changes, the directional indication will also change accordingly.

[0140] In the description of the present invention, the terms "first" and "second" are only used to facilitate the description of different components or names, and cannot be understood as indicating or implying a sequential relationship, relative importance, or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features.

[0141] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0142] It should be noted that although the specific embodiments of the present invention are described in detail in conjunction with the accompanying drawings, it should not be understood as limiting the scope of protection of the present invention. Within the scope described in the claims, various modifications and variations that can be made by those skilled in the art without creative work still belong to the scope of protection of the present invention.

[0143] The examples of the embodiments of the present invention are intended to concisely illustrate the technical features of the embodiments of the present invention so that those skilled in the art can intuitively understand the technical features of the embodiments of the present invention, and are not intended to be improper limitations of the embodiments of the present invention.

[0144] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for characterizing multi-component fronts of multi-component gas flooding and their evolution law, characterized in that: include: According to the geological parameters of the research block, a multi-component gas drive reservoir mechanism model is established; Based on the multi-component gas drive multi-component reservoir mechanism model, a multi-component gas drive reservoir numerical simulation is performed to obtain a numerical simulation result; Before the front edge of each component advances to the production well, the front edge of each component is divided based on the numerical simulation result, and a visual front edge advancement line is drawn according to the front edge of each component; According to the numerical simulation results and the visualized front advancement line, the distribution patterns of the oil phase, gas phase and each component along the route are divided into regions to obtain the regional distribution results of each component; According to the numerical simulation results, the visualized front advancing line and the regional distribution results of each component, the injection volume step or time step is determined, and the saturation and content data of each component on the mainstream line are extracted once every injection volume step or time step until all component fronts advance to the production wells, and the relationship between the distance between the fronts of each component along the injection and production wells and the injection volume or injection time is plotted; The temporal and spatial evolution law of the front of each component is quantitatively characterized according to the change relationship, the different production stages of multi-gas drive are divided, and the duration of different production stages is determined.

2. The method according to claim 1, characterized in that The geological parameters include reservoir porosity, reservoir permeability, reservoir heterogeneity, reservoir temperature, and reservoir pressure.

3. The method according to claim 1, characterized in that The method of dividing the front edges of the components based on the numerical simulation results before the front edges of the components advance to the production wells, and drawing a visual front advancement line according to the front edges of the components, comprises: Before the front of each component advances to the production well, select the oil phase and gas phase saturation distribution profile, and the distribution profile of each component of the oil phase and gas phase at a certain injection amount or a certain time from the numerical simulation results; According to the characteristics of the profile, the front edge of each component is divided into a component sweep front edge, wherein the front edge includes a carbon-rich front edge, an effective component front edge, an N2-rich front edge, a CO2-rich front edge and a gas slug front edge; A visual front advancement line is drawn on the saturation profile according to the front edges of each component.

4. The method according to claim 3, characterized in that According to the numerical simulation results and the visualized front advancement line, the distribution law of the oil phase, gas phase and their components along the way is divided into regions to obtain the regional distribution results of each component, including: Before the front of each component advances to the production well, the oil phase and gas phase saturation and the molar content data of each component of the oil phase and gas phase on the main flow line between the injection well and the production well at a certain injection volume or a certain time are selected from the numerical simulation results; Plot the relationship between the oil phase and gas phase saturation and the content of each component of the oil phase and gas phase on the main flow line and the distance between the injection and production wells; Determine the distribution law of the oil phase, the gas phase and their components along the process according to the change curve; The distribution law along the route is divided into regions according to the visualized front advancement line to obtain the regional distribution results of each component.

5. The method according to claim 4, characterized in that The regional distribution results of each component include the original oil zone, the oil phase transition zone, the gas-rich transition zone, the gas-rich zone, the N2 immiscible zone, the CO2 immiscible zone and the multi-gas slug zone.

6. The method according to claim 4, characterized in that Also includes: The dimensionless distance is defined according to the distance between the injection and production wells: L D =L Component / L Well Among them, L D is dimensionless distance, dimensionless; L Component is the component migration distance on the mainstream line, m; L Well is the distance between injection and production wells, m; When L D = 0, it means that each component is at the bottom of the injection well; when L D When =1, it means that each component migrates to the bottom of the production well.

7. The method according to claim 1, characterized in that The production stages include the original oil production stage, the solution gas production stage, the gas-rich transition stage, the gas-rich drive stage, the N2 immiscible drive stage, the CO2 immiscible drive stage and the multi-gas segment plug drive stage.

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