Numerical simulation method and device for time-varying physical properties during waterflooding development of medium- and high-permeability oil reservoirs

Abstract

The present invention provides a method and apparatus for numerically simulating the time-varying physical properties of medium- and high-permeability oil reservoirs during waterflooding development. The method and apparatus relate to the technical field of oil extraction and specifically include the following steps: dividing the oil reservoir or reservoir to obtain grid cells; obtaining the formation oil viscosity of the grid cells, the oil-water relative permeability curves at different waterflooding multiples, and the conductivity between adjacent grid cells at the same time step to establish an oil reservoir simulation model; based on the oil reservoir simulation model, obtaining the waterflooding multiple of the grid cells, and obtaining the grid cell permeability, formation oil viscosity, and oil-water relative permeability curve based on the waterflooding multiple of the grid cells. The method and apparatus provided by the present invention can characterize changes in reservoir physical properties caused by long-term waterflooding, alleviating the technical problem of existing commercial software being unable to simulate the time-varying effects of reservoirs, and guiding the development and management of medium- and high-permeability, high-water-content oil reservoirs.

Description

Technical Field

[0001] The present invention relates to the technical field of oil extraction, and in particular to a method and device for simulating time-varying physical properties in the process of water injection development of medium- and high-permeability oil reservoirs. Background Art

[0002] During the long-term waterflooding development process, medium- and high-permeability oil reservoirs have now generally entered the high water-cut stage. The analysis results of core sampling data, field logging data, and reservoir dynamic development data all show that after long-term waterflooding development, the macro- and micro-structures and fluid composition characteristics of the reservoir have undergone significant changes compared with the initial stage of reservoir development. Among them, the key parameters of reservoir physical properties - permeability, formation crude oil viscosity, and oil-water relative permeability - have all undergone significant changes. The changes in these physical parameters have a significant impact on the seepage pattern.

[0003] During waterflooding development of medium- and high-permeability sandstone reservoirs, subsurface fluid movement causes changes in reservoir micro-parameters (such as rock skeleton structure, pore throat radius, and clay content). Field observations show that while formation porosity changes minimally and without discernible patterns, permeability and relative permeability curves in medium- and high-permeability sandstone reservoirs exhibit significant variations, leading to changes in sweep efficiency and oil displacement efficiency, directly impacting reservoir recovery, development dynamics, and remaining oil distribution. Therefore, the time-varying physical property parameters used in reservoir numerical simulations are considered to be permeability, relative permeability curves, and fluid viscosity. Mathematical models describing time-varying reservoir physical properties primarily use macro-parameters (permeability and relative permeability) to indirectly reflect changes in micro-parameters as a function of water injection rate. Numerical simulations also primarily use changes in macro-parameters such as permeability and relative permeability curves to comprehensively reflect changes in these various micro-parameters.

[0004] Some oilfields are now entering the ultra-high water-cut development phase. Long-term water injection and flushing have caused significant changes in reservoir properties, affecting the patterns of oil-water movement and the distribution of remaining oil. Existing commercial reservoir numerical simulation software fails to account for the time-varying nature of reservoir physical parameters, and quantitative descriptions of remaining oil are no longer adequate for the refined development needs of the ultra-high water-cut phase. Therefore, establishing a model for the continuous variation of reservoir parameters with water injection and flushing, reflecting the diversity and directionality of the time-varying patterns of reservoir physical properties, and developing numerical simulation software for reservoirs with time-varying physical properties to address the shortcomings of existing commercial software in simulating the time-varying effects of reservoirs are of great significance to the development of reservoir numerical simulation technology, the management and development of medium- and high-permeability high-water-cut reservoirs, and the understanding of seepage patterns. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a method and device for numerical simulation of time-varying physical properties during water injection development of medium- and high-permeability oil reservoirs, so as to establish a model for the continuous change of reservoir parameters with water injection flushing, characterize the changes in reservoir physical properties caused by long-term water injection flushing, alleviate the technical problem that existing commercial software cannot simulate the time-varying effects of reservoirs, and guide the development and management of medium- and high-permeability high-water-content oil reservoirs.

[0006] The present invention provides a method for numerically simulating time-varying physical properties during water flooding development of medium- and high-permeability oil reservoirs, which specifically comprises the following steps:

[0007] Divide the oil reservoir or reservoir into grid cells;

[0008] Obtain the formation oil viscosity of the grid unit, the oil-water relative permeability curve under different water injection flushing multiples, and the conductivity between adjacent grid units at the same time step to establish a reservoir simulation model;

[0009] Based on the reservoir simulation model, the water injection multiple of the grid unit is obtained, and based on the water injection multiple of the grid unit, the permeability, formation oil viscosity and oil-water relative permeability curve of the grid unit are obtained.

[0010] Preferably, the following method is used to obtain the conductivity between adjacent grid cells at the same time step:

[0011] Obtain the initial permeability of the grid cell, the water injection flushing multiple, and the maximum permeability of the grid cell after water injection flushing to obtain the permeability of the grid cell, and obtain the cell permeability at different time steps;

[0012] The conductivity between adjacent grid cells at different time steps is obtained based on the cell permeability at different time steps.

[0013] Preferably, the following formula is used to construct a time-varying permeability model to obtain the cell permeability at different time steps:

[0014] k(x)=k max -(k max -k int )·exp(-b k x)

[0015] k int —initial permeability of the grid cell;

[0016] k max —The maximum permeability of the grid cell after water injection;

[0017] k(x)—grid cell permeability (mD),

[0018] x—water injection flushing multiple (water injection flushing pore volume multiple), dimensionless;

[0019] b k —Permeability time-varying factor, dimensionless;

[0020] The following formula is used to obtain the conductivity between adjacent grid cells at different time steps:

[0021]

[0022] A i —The seepage area between grid cell i and adjacent grid cell j;

[0023] A j —The seepage area between grid cell j and the adjacent grid cell i;

[0024] d i —The seepage distance between grid cell i and adjacent grid cell j;

[0025] d j —The seepage distance between grid cell j and the adjacent grid cell i;

[0026] T i —The conductivity from grid cell i to adjacent grid cell j;

[0027] and

[0028] T j —The conductivity from grid cell j to adjacent grid cell i,

[0029] and

[0030] T ij —time-varying conductivity between adjacent grid cells i and j;

[0031] u—iteration step of numerical simulation calculation, n+1 is the time step;

[0032] k i (x i )—grid unit i in the water injection flushing multiple x i The permeability when

[0033] k j (x j ) is the pore volume of grid unit j when water injection is multiple x j permeability under the conditions.

[0034] Preferably, the step of obtaining the formation oil viscosity of the grid unit includes:

[0035] The formation oil viscosity of the grid unit in the initial stage of reservoir development and the maximum viscosity of the formation oil after water injection and flushing are obtained, and the water injection flushing multiple is used to obtain the formation oil viscosity of the grid unit.

[0036] Preferably, the following formula is constructed to obtain the formation oil viscosity of the grid cell:

[0037] μ(x)=μ max -(μ max -μ int )·exp(-b μ x);

[0038] μ int —Crude oil viscosity in the initial stage of grid unit reservoir development;

[0039] μ max —The maximum formation oil viscosity obtained after water injection flushing;

[0040] μ(x)—grid unit formation oil viscosity;

[0041] x—water injection flushing multiple, dimensionless;

[0042] b μ —Time-varying factor of formation oil viscosity, dimensionless.

[0043] Preferably, the step of obtaining the water injection multiple of the grid unit based on the reservoir simulation model, and obtaining the permeability formation oil viscosity and oil-water relative permeability curve of the grid unit based on the water injection multiple of the grid unit includes:

[0044] The grid cell permeability is obtained using the following formula:

[0045] k(x * ) n =k max -(k max -k int )·exp(-b k x * );

[0046] k(x * ) n —Current time step n and water injection multiple x of grid cell * Grid cell permeability under conditions;

[0047] x * —Water injection multiple of grid cells;

[0048] k int —initial permeability of the grid cell;

[0049] k max —The maximum permeability of the grid cell after water injection;

[0050] μ(x * ) n =μmax -(μ max -μ int )·exp(-b μ x * )

[0051] μ int —Crude oil viscosity in the initial stage of grid unit reservoir development;

[0052] μ max —The maximum formation oil viscosity obtained after water injection flushing;

[0053] μ(x * ) n —Current time step n and current water injection multiple x * Grid cell formation oil viscosity under the conditions.

[0054] Preferably, the oil-water relative permeability curve is obtained using the following formula:

[0055] Update the oil-water relative permeability curve using linear interpolation:

[0056] and x1≤x * ≤x2

[0057] And x1≤x * ≤x2

[0058] Where, are the current time step n and the current water injection flushing multiple x respectively * The oil phase relative permeability and water phase relative permeability under different conditions and water saturation conditions;

[0059] is the relative permeability of the oil phase obtained through physical experiments when the water injection flushing multiples are x1 and x2 respectively and under different water saturation conditions;

[0060] is the relative permeability of the water phase obtained through physical experiments when the water injection flushing multiples are x1 and x2 respectively and under different water saturation conditions.

[0061] Preferably, the oil-water relative permeability curve is obtained using the following formula:

[0062] The oil-water relative permeability curve is updated using nonlinear interpolation:

[0063] and x1≤x * ≤x2

[0064] and x1≤x * ≤x2

[0065] Where, are the current time step n and the current water injection flushing multiple x respectively * The oil phase relative permeability and water phase relative permeability under different conditions and water saturation conditions;

[0066] is the relative permeability of the oil phase obtained through physical experiments when the water injection flushing multiples are x1 and x2 respectively and under different water saturation conditions;

[0067] is the relative permeability of the water phase obtained through physical experiments when the water injection flushing multiples are x1 and x2 respectively and under different water saturation conditions.

[0068] In another aspect, the present invention provides a device for simulating the time-varying physical properties of medium- and high-permeability oil reservoirs during water flooding development, comprising:

[0069] Unit division module: used to divide the reservoir or reservoir to obtain grid units;

[0070] Model building module: used to obtain the formation oil viscosity of the grid unit, the oil-water relative permeability curve under different water injection flushing multiples, and the conductivity between adjacent grid units at the same time step to establish a reservoir simulation model;

[0071] Digital simulation module: Based on the reservoir simulation model, the water injection multiple of the grid unit is obtained, and based on the water injection multiple of the grid unit, the permeability, formation oil viscosity and oil-water relative permeability curve of the grid unit are obtained.

[0072] The embodiments of the present invention bring the following beneficial effects: The present invention provides a method and apparatus for numerically simulating the time-varying physical properties of medium- and high-permeability oil reservoirs during water injection development, specifically comprising the following steps: dividing the oil reservoir or reservoir to obtain grid cells; obtaining the formation oil viscosity of the grid cells, the oil-water relative permeability curves at different water injection flushing multiples, and the conductivity between adjacent grid cells at the same time step to establish an oil reservoir simulation model; based on the oil reservoir simulation model, obtaining the water injection multiple of the grid cells, and obtaining the grid cell permeability, formation oil viscosity, and oil-water relative permeability curve based on the water injection multiple of the grid cells. The method and apparatus provided by the present invention can characterize the changes in reservoir physical properties caused by long-term water injection flushing, alleviate the technical problem that existing commercial software cannot simulate the time-varying effects of reservoirs, and guide the development and management of medium- and high-permeability, high-water-content oil reservoirs.

[0073] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or understood by practicing the present invention. The purposes and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings.

[0074] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0076] Figure 1 A flow chart of a method for numerically simulating time-varying physical properties during water flooding development of medium- and high-permeability oil reservoirs provided by an embodiment of the present invention;

[0077] Figure 2 A schematic diagram of the relationship between water injection flushing multiple and formation permeability in a method for time-varying numerical simulation of physical properties during water injection development of medium- and high-permeability oil reservoirs provided by an embodiment of the present invention;

[0078] Figure 3 A schematic diagram of the relationship between the water injection flushing multiple and the viscosity of the formation crude oil in a method for time-varying numerical simulation of physical properties during water injection development of medium- and high-permeability oil reservoirs provided by an embodiment of the present invention;

[0079] Figure 4 A schematic diagram of a reservoir grid model for a method of numerically simulating time-varying physical properties during waterflooding development of medium- and high-permeability oil reservoirs provided by an embodiment of the present invention;

[0080] Figure 5 The present invention provides a method for simulating the time-varying physical properties of a medium- and high-permeability oil reservoir during waterflooding development, and a diagram showing the influence of the time-varying effect of reservoir physical properties on the cumulative production. DETAILED DESCRIPTION

[0081] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0082] At present, some oil fields have entered the stage of ultra-high water-cut development as a whole. The long-term water injection and flushing have caused significant changes in reservoir physical properties, affecting the law of oil-water movement and the distribution of residual oil. Existing commercial reservoir numerical simulation software has failed to take into account the time-varying phenomenon of reservoir physical property parameters. The quantitative description of residual oil can no longer meet the needs of fine development in the ultra-high water-cut development stage. Based on this, the embodiment of the present invention provides a method and device for numerical simulation of time-varying physical properties in the process of water injection development of medium- and high-permeability oil reservoirs. A model of the continuous change of reservoir parameters with water injection and flushing can be established, and the changes in reservoir physical properties caused by long-term water injection and flushing can be characterized, thereby alleviating the technical problem that existing commercial software cannot simulate the time-varying effects of reservoirs, and guiding the development and management of medium- and high-permeability high-water-cut oil reservoirs.

[0083] To facilitate understanding of this embodiment, a method for numerical simulation of time-varying physical properties during water flooding development of medium- and high-permeability oil reservoirs disclosed in an embodiment of the present invention is first introduced in detail.

[0084] Example 1:

[0085] The present invention provides a method for numerically simulating time-varying physical properties during water flooding development of medium- and high-permeability oil reservoirs, which specifically comprises the following steps:

[0086] Divide the oil reservoir or reservoir into grid cells;

[0087] Obtain the formation oil viscosity of the grid unit, the oil-water relative permeability curve under different water injection flushing multiples, and the conductivity between adjacent grid units at the same time step to establish a reservoir simulation model;

[0088] Based on the reservoir simulation model, the water injection multiple of the grid unit is obtained, and based on the water injection multiple of the grid unit, the permeability, formation oil viscosity and oil-water relative permeability curve of the grid unit are obtained.

[0089] Preferably, the following method is used to obtain the conductivity between adjacent grid cells at the same time step:

[0090] Obtain the initial permeability of the grid cell, the water injection flushing multiple, and the maximum permeability of the grid cell after water injection flushing to obtain the permeability of the grid cell, and obtain the cell permeability at different time steps;

[0091] The conductivity between adjacent grid cells at different time steps is obtained based on the cell permeability at different time steps.

[0092] Preferably, the following formula is used to construct a time-varying permeability model to obtain the cell permeability at different time steps:

[0093] k(x)=k max -(k max -k int)·exp(-b k x)

[0094] k int —initial permeability of the grid cell;

[0095] k max —The maximum permeability of the grid cell after water injection;

[0096] k(x)—grid cell permeability (mD),

[0097] x—water injection flushing multiple (water injection flushing pore volume multiple), dimensionless;

[0098] b k —Permeability time-varying factor, dimensionless;

[0099] The following formula is used to obtain the conductivity between adjacent grid cells at different time steps:

[0100]

[0101] A i —The seepage area between grid cell i and adjacent grid cell j;

[0102] A j —The seepage area between grid cell j and the adjacent grid cell i;

[0103] d i —The seepage distance between grid cell i and adjacent grid cell j;

[0104] d j —The seepage distance between grid cell j and the adjacent grid cell i;

[0105] T i —The conductivity from grid cell i to adjacent grid cell j;

[0106] and

[0107] T j —The conductivity from grid cell j to adjacent grid cell i,

[0108] and

[0109] T ij —time-varying conductivity between adjacent grid cells i and j;

[0110] u—iteration step of numerical simulation calculation, n+1 is the time step;

[0111] k i (x i )—grid unit i in the water injection flushing multiple xi The permeability when

[0112] k j (x j ) is the pore volume of grid unit j when water injection is multiple x j permeability under the conditions.

[0113] Preferably, the step of obtaining the formation oil viscosity of the grid unit includes:

[0114] The formation oil viscosity of the grid unit in the initial stage of reservoir development and the maximum viscosity of the formation oil after water injection and flushing are obtained, and the water injection flushing multiple is used to obtain the formation oil viscosity of the grid unit.

[0115] Preferably, the following formula is constructed to obtain the formation oil viscosity of the grid cell:

[0116] μ(x)=μ max -(μ max -μ int )·exp(-b μ x);

[0117] μ int —Crude oil viscosity in the initial stage of grid unit reservoir development;

[0118] μ max —The maximum formation oil viscosity obtained after water injection flushing;

[0119] μ(x)—grid unit formation oil viscosity;

[0120] x—water injection flushing multiple, dimensionless;

[0121] b μ —Time-varying factor of formation oil viscosity, dimensionless.

[0122] Preferably, the step of obtaining the water injection multiple of the grid unit based on the reservoir simulation model, and obtaining the permeability formation oil viscosity and oil-water relative permeability curve of the grid unit based on the water injection multiple of the grid unit includes:

[0123] The grid cell permeability is obtained using the following formula:

[0124] k(x * ) n =k max -(k max -k int )·exp(-b k x * );

[0125] k(x * ) n —Current time step n and water injection multiple x of grid cell* Grid cell permeability under conditions;

[0126] x * —Water injection multiple of grid cells;

[0127] k int —initial permeability of the grid cell;

[0128] k max —The maximum permeability of the grid cell after water injection;

[0129] μ(x * ) n =μ max -(μ max -μ int )·exp(-b μ x * )

[0130] μ int —Crude oil viscosity in the initial stage of grid unit reservoir development;

[0131] μ max —The maximum formation oil viscosity obtained after water injection flushing;

[0132] μ(x * ) n —Current time step n and current water injection multiple x * Grid cell formation oil viscosity under the conditions.

[0133] Preferably, the oil-water relative permeability curve is obtained using the following formula:

[0134] Update the oil-water relative permeability curve using linear interpolation:

[0135] and x1≤x * ≤x2

[0136] and x1≤x * ≤x2

[0137] Where, are the current time step n and the current water injection flushing multiple x respectively * The oil phase relative permeability and water phase relative permeability under different conditions and water saturation conditions;

[0138] is the relative permeability of the oil phase obtained through physical experiments when the water injection flushing multiples are x1 and x2 respectively and under different water saturation conditions;

[0139] is the relative permeability of the water phase obtained through physical experiments when the water injection flushing multiples are x1 and x2 respectively and under different water saturation conditions.

[0140] Preferably, the oil-water relative permeability curve is obtained using the following formula:

[0141] The oil-water relative permeability curve is updated using nonlinear interpolation:

[0142] and x1≤x * ≤x2

[0143] and x1≤x * ≤x2

[0144] Where, are the current time step n and the current water injection flushing multiple x respectively * The oil phase relative permeability and water phase relative permeability under different conditions and water saturation conditions;

[0145] is the relative permeability of the oil phase obtained through physical experiments when the water injection flushing multiples are x1 and x2 respectively and under different water saturation conditions;

[0146] is the relative permeability of the water phase obtained through physical experiments when the water injection flushing multiples are x1 and x2 respectively and under different water saturation conditions.

[0147] Example 2:

[0148] The second embodiment of the present invention provides a specific example of the first embodiment of the present invention:

[0149] The initial permeability k of the grid unit measured in the indoor experiment in the embodiment provided by the present invention is int The core permeability is 360mD, and the water injection flushing multiples are 500, 1000, 1500 and 2000. The permeability under the water injection flushing multiple of 2000 is the maximum permeability k max The permeability time-varying model is used to fit the core permeability under different water injection multiples to obtain the permeability time-varying factor b of the grid unit. k is 0.00123, and the relationship between water injection flushing multiple and permeability is as follows Figure 2 As shown. By analogy, the time-varying factors of permeability at different levels within the reservoir are obtained, and the permeability of the grid cells at different water injection multiples is obtained as follows:

[0150] k(x)=620-260·exp(-0.00123x);

[0151] In the embodiment provided by the present invention, the viscosity of crude oil in the grid unit reservoir at the initial stage of development μ int The formation oil viscosity is 3.8 mPa·s, and the water injection flushing multiples are 500, 1000, 1500 and 2000 respectively. The maximum formation oil viscosity μ after water injection flushing under the water injection flushing multiple of 2000 is max The time-varying model of formation oil viscosity is used to fit the formation oil viscosity at different water injection multiples to obtain the time-varying factor b of the formation oil viscosity. μ is 0.00117. The relationship between water injection ratio and formation oil viscosity is as follows: Figure 3 When the formation oil viscosity varies widely within the reservoir, the time-varying factor of the formation oil under different viscosity conditions can be measured, and the expression for the formation oil viscosity under different water injection ratios can be obtained as follows:

[0152] μ(x)=7.5-3.7·exp(-0.0017x);

[0153] In the embodiment provided by the present invention, the oil-water relative permeability curves of the reservoir permeability at different water injection flushing multiples include: in: The water flushing multiple is x l Oil phase relative permeability curves under different water saturation conditions; The water flushing multiple is x l When , and the water phase relative permeability curves under different water saturation conditions, l=1,2,3...n', n' refers to the total number of oil-water relative permeability curves;

[0154] Furthermore, the oil-water relative permeability data at the initial stage and under the condition of a water injection flushing ratio of 1000 times are shown in Table 1.

[0155] Table 1 Oil-water relative permeability data at initial and water injection flushing times of 1000

[0156]

[0157]

[0158] When the grid cell step size is 10 meters and the grid seepage area is 10 square meters, the conductivity calculation method of adjacent grid cells is:

[0159] T i =k i (x i )=620-260·exp(-0.00123x i )

[0160] T j =kj (x j )=620-260·exp(-0.00123x j )

[0161]

[0162] T i =620-260·exp(-0.00123x i )

[0163] T j =620-260·exp(-0.00123x j )

[0164] In the embodiment provided by the present invention, the reservoir simulation model established is as follows Figure 4 As shown in Figure 1, the total number of grids is 12. The reservoir simulation model includes input / output control parameters, fluid physical parameters (oil density is 0.72 g / cm3, water density is 1.0 g / cm3) and injection and production control parameters (the locations of injection wells and production wells are shown in Figure 1). Figure 4 As shown, the injection rate of the injection well is 20m3, and the production rate of the production well is 20m3). Modify the traditional reservoir numerical simulation software so that the modified reservoir numerical simulation software can read the oil-water relative permeability curves of different water overflow ratios, calculate the reservoir permeability and crude oil viscosity of different water overflow ratios, and then calculate the conductivity at different time steps and iteration steps, and develop time-varying reservoir numerical simulation software;

[0165] For example, the time-varying reservoir numerical simulation software developed by the application and the reservoir simulation model used can realistically reflect the impact of the time-varying characteristics of reservoir physical properties on the development effect during the reservoir injection development process;

[0166] Tables 2 and 3 show the changes in reservoir permeability after 1, 100, 360, and 1000 days of waterflooding. The simulation results show that after 100 days of waterflooding, the reservoir permeability has increased from the initial 360 mD to 370-380 mD. By 360 days of waterflooding, the permeability has increased to nearly 450 mD.

[0167] Table 2 Reservoir permeability data after different time

[0168]

[0169] Table 3 Reservoir permeability data after different time

[0170]

[0171] Tables 4 and 5 show the distribution of residual oil saturation of the reservoir system under different simulated water injection development times. It can be seen from the figures that the residual oil saturation of the reservoir system has dropped from 0.52 to 0.65 in the initial stage to 0.35 at 1000 days.

[0172] Table 4 Data of reservoir remaining oil saturation after different time periods

[0173]

[0174] Table 5 Data of reservoir remaining oil saturation after different time periods

[0175]

[0176] Figure 5 The cumulative production comparison curve is whether the time-varying effect of reservoir physical properties is considered. The results show that when the time-varying effects of reservoir permeability, formation oil viscosity and oil-water relative permeability are considered, the cumulative production decreases, indicating that after long-term water injection development of medium and high permeability reservoirs, the reservoir physical properties can have a greater impact on oil well production as the water injection flushing multiple increases.

[0177] Example 3:

[0178] A third embodiment of the present invention provides a device for simulating time-varying physical properties during water flooding development of medium- and high-permeability oil reservoirs, comprising:

[0179] Unit division module: used to divide the reservoir or reservoir to obtain grid units;

[0180] Model building module: used to obtain the formation oil viscosity of the grid unit, the oil-water relative permeability curve under different water injection flushing multiples, and the conductivity between adjacent grid units at the same time step to establish a reservoir simulation model;

[0181] Digital simulation module: Based on the reservoir simulation model, the water injection multiple of the grid unit is obtained, and based on the water injection multiple of the grid unit, the permeability, formation oil viscosity and oil-water relative permeability curve of the grid unit are obtained.

[0182] The device provided in the embodiment of the present invention has the same implementation principle and technical effects as those in the aforementioned method embodiment. For the sake of brief description, for matters not mentioned in the device embodiment, reference can be made to the corresponding content in the aforementioned method embodiment.

[0183] In all examples shown and described herein, any specific values ​​should be interpreted as merely exemplary and not limiting, and thus other examples of the exemplary embodiments may have different values.

[0184] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0185] The flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the systems, methods and computer program products according to multiple embodiments of the present invention. In this regard, each box in the flowchart or block diagram can represent a module, program segment or part of code, and the module, program segment or part of code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order than that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart, can be implemented with a dedicated hardware-based system that performs the specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0186] In addition, in the description of the embodiments of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0187] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0188] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0189] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. There may be other division methods in actual implementation. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed may be through some communication interface, indirect coupling or communication connection of devices or units, which may be electrical, mechanical or other forms.

[0190] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0191] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0192] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the above-described embodiments, those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the above-described embodiments within the technical scope disclosed by the present invention, or replace some of the technical features therein with equivalents. Such modifications, changes, or replacements do not deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A method for simulating the time-varying physical properties of medium- and high-permeability oil reservoirs during water flooding development, characterized in that: The specific steps include: Divide the oil reservoir or reservoir into grid cells; Obtain the formation oil viscosity of the grid unit, the oil-water relative permeability curve under different water injection flushing multiples, and the conductivity between adjacent grid units at the same time step to establish a reservoir simulation model; Based on the reservoir simulation model, obtaining the water injection multiple of the grid unit, and obtaining the permeability, formation oil viscosity and oil-water relative permeability curve of the grid unit based on the water injection multiple of the grid unit; The following method is used to obtain the conductivity between adjacent grid cells at the same time step: Obtain the initial permeability of the grid cell, the water injection flushing multiple, and the maximum permeability of the grid cell after water injection flushing to obtain the permeability of the grid cell, and obtain the cell permeability at different time steps; Obtain the conductivity between adjacent grid cells at different time steps based on the cell permeability at different time steps; The following formula is used to construct a time-varying permeability model to obtain the cell permeability at different time steps: k(x)=k max -(k max -k int )·exp(-b k x) k int —initial permeability of the grid cell; k max —The maximum permeability of the grid cell after water injection; k(x)—grid cell permeability (mD), x—water injection flushing multiple (water injection flushing pore volume multiple), dimensionless; b k —Permeability time-varying factor, dimensionless; The following formula is used to obtain the conductivity between adjacent grid cells at different time steps: A i —The seepage area between grid cell i and adjacent grid cell j; A j —The seepage area between grid cell j and the adjacent grid cell i; d i —The seepage distance between grid cell i and adjacent grid cell j; d j —The seepage distance between grid cell j and the adjacent grid cell i; T i —The conductivity from grid cell i to adjacent grid cell j; and T j —The conductivity from grid cell j to adjacent grid cell i, and T ij —time-varying conductivity between adjacent grid cells i and j; u—iteration step of numerical simulation calculation, n+1 is the time step; k i (x i )—grid unit i in the water injection flushing multiple x i The permeability when k j (x j ) is the pore volume of grid unit j when water injection is multiple x j permeability under the conditions.

2. The method according to claim 1, characterized in that The step of obtaining the formation oil viscosity of the grid unit includes: The formation oil viscosity of the grid unit in the initial stage of reservoir development and the maximum viscosity of the formation oil after water injection and flushing are obtained, and the water injection flushing multiple is used to obtain the formation oil viscosity of the grid unit.

3. The method according to claim 2, characterized in that The following formula is constructed to obtain the formation oil viscosity of the grid cell: μ(x)=μ max -(m max -m int )·exp(-b μ x); μ int —Crude oil viscosity in the initial stage of grid unit reservoir development; μ max —The maximum formation oil viscosity obtained after water injection flushing; μ(x)—grid unit formation oil viscosity; x—water injection flushing multiple, dimensionless; b μ —Time-varying factor of formation oil viscosity, dimensionless.

4. The method according to claim 1, wherein The steps of obtaining the water injection multiple of the grid unit based on the reservoir simulation model, and obtaining the permeability formation oil viscosity and oil-water relative permeability curve of the grid unit based on the water injection multiple of the grid unit include: The grid cell permeability is obtained using the following formula: k(x * ) n =k max -(k max -k int )·exp(-b k x * ); k(x * ) n —Current time step n and water injection multiple x of grid cell * Grid cell permeability under conditions; x * —Water injection multiple of grid cells; k int —initial permeability of the grid cell; k max —The maximum permeability of the grid cell after water injection; μ(x * ) n =μ max -(m max -m int )·exp(-b μ x * ) μ int —Crude oil viscosity in the initial stage of grid unit reservoir development; μ max —The maximum formation oil viscosity obtained after water injection flushing; μ(x * ) n —Current time step n and current water injection multiple x * Grid cell formation oil viscosity under the conditions.

5. The method according to claim 1, characterized in that The oil-water relative permeability curve is obtained using the following formula: Update the oil-water relative permeability curve using linear interpolation: and x1≤x * ≤x2 and x1≤x * ≤x2 Where, are the current time step n and the current water injection flushing multiple x respectively * The oil phase relative permeability and water phase relative permeability under different conditions and water saturation conditions; is the relative permeability of the oil phase obtained through physical experiments when the water injection flushing multiples are x1 and x2 respectively and under different water saturation conditions; is the relative permeability of the water phase obtained through physical experiments when the water injection flushing multiples are x1 and x2 respectively and under different water saturation conditions.

6. The method according to claim 1, characterized in that The oil-water relative permeability curve is obtained using the following formula: The oil-water relative permeability curve is updated using nonlinear interpolation: and x1≤x * ≤x2 and x1≤x * ≤x2 Where, are the current time step n and the current water injection flushing multiple x respectively * The oil phase relative permeability and water phase relative permeability under different conditions and water saturation conditions; is the relative permeability of the oil phase obtained through physical experiments when the water injection flushing multiples are x1 and x2 respectively and under different water saturation conditions; is the relative permeability of the water phase obtained through physical experiments when the water injection flushing multiples are x1 and x2 respectively and under different water saturation conditions.

7. A numerical simulation device for time-varying physical properties during water flooding development of medium- and high-permeability oil reservoirs, suitable for the method of claim 1, characterized in that: include: Unit division module: used to divide the reservoir or reservoir to obtain grid units; Model building module: used to obtain the formation oil viscosity of the grid unit, the oil-water relative permeability curve under different water injection flushing multiples, and the conductivity between adjacent grid units at the same time step to establish a reservoir simulation model; Digital simulation module: based on the reservoir simulation model, obtains the water injection multiple of the grid unit, and obtains the permeability, formation oil viscosity and oil-water relative permeability curve of the grid unit based on the water injection multiple of the grid unit; Get the conductivity between adjacent grid cells at the same time step: Obtain the initial permeability of the grid cell, the water injection flushing multiple, and the maximum permeability of the grid cell after water injection flushing to obtain the permeability of the grid cell, and obtain the cell permeability at different time steps; Obtain the conductivity between adjacent grid cells at different time steps based on the cell permeability at different time steps; Construct a time-varying permeability model to obtain the cell permeability at different time steps: k(x)=k max -(k max -k int )·exp(-b k x) k int —initial permeability of the grid cell; k max —The maximum permeability of the grid cell after water injection; k(x)—grid cell permeability (mD), x—water injection flushing multiple (water injection flushing pore volume multiple), dimensionless; b k —Permeability time-varying factor, dimensionless; The following formula is used to obtain the conductivity between adjacent grid cells at different time steps: A i —The seepage area between grid cell i and adjacent grid cell j; A j —The seepage area between grid cell j and the adjacent grid cell i; d i —The seepage distance between grid cell i and adjacent grid cell j; d j —The seepage distance between grid cell j and the adjacent grid cell i; T i —The conductivity from grid cell i to adjacent grid cell j; and T j —The conductivity from grid cell j to adjacent grid cell i, and T ij —time-varying conductivity between adjacent grid cells i and j; u—iteration step of numerical simulation calculation, n+1 is the time step; k i (x i )—grid unit i in the water injection flushing multiple x i The permeability when k j (x j ) is the pore volume of grid unit j when water injection is multiple x j permeability under the conditions.

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