A method for evaluating the effect of crude oil reflux in water-drive reservoirs on increasing production and injection.

Abstract

This invention provides a method for evaluating the effect of crude oil reflux enhancement in water-drive reservoirs, including calculating the physical properties of a particle from the well point, calculating the particle vector velocity at time t0, calculating the particle position at time t1, calculating the particle reflux direction time, calculating the particle reflux capacity, and calculating the enhancement effect of the particle reflux capacity. The method calculates the crude oil reflux enhancement effect based on the relationship between the original reflux capacity of the particle and the reflux capacity after adjusting the injection and production well fluid volumes. This invention, after adjusting the injection and production well fluid volumes, can quickly and effectively quantify the crude oil reflux enhancement effect by observing the changes in the planar particle reflux capacity, improving the speed of scheme design by on-site technicians and having significant practical value for oilfield flow field adjustment technology.

Description

Technical Field

[0001] This invention relates to the field of characterization of the injection-production optimization flow field in water-driven reservoirs, and particularly to a method for evaluating the effect of crude oil reflux in water-driven reservoirs on production enhancement and injection improvement. Background Technology

[0002] Adjusting the fluid volume in oil and water wells is a common production enhancement measure in oilfield development. It is generally believed that increasing the fluid production rate can improve the recovery rate of underground crude oil. However, after an oilfield enters a period of high and ultra-high water cut, the remaining crude oil becomes highly dispersed. Due to the long-term influence of water drive on the dominant flow field, simple and blind increases in production and injection may not achieve the desired results. With the development of integrated reservoir technology, the balanced water drive fluid volume optimization method has been gradually promoted and applied in major oilfields, achieving good development results. However, balanced water drive technology is mainly applied in comprehensive three-dimensional adjustments in oilfields, and it cannot be well applied in daily well group production adjustments. There is still a lack of scientific guidance methods for fluid volume adjustment during single-well group adjustments in oilfields, and the effect of crude oil reflux after fluid volume adjustment in injection and production wells cannot be quickly, intuitively, and quantitatively evaluated.

[0003] The volume of fluid in oil and water wells directly affects the bottom hole pressure, thus influencing the distribution of the underground flow field. The flow field is a representation of underground fluid flow, and the core of reservoir engineering is to adjust the flow field to allow more underground crude oil to flow to the surface. Therefore, with fixed well locations, daily adjustments to the fluid volume of injection and production wells are one of the main tasks in oilfield operations. Scientifically sound fluid volume is crucial for improving oil recovery rates during oilfield development. In the high water-cut stage of oilfield development, the design of fluid volumes in injection and production wells is closely related to the distribution of remaining underground crude oil. The prediction and evaluation of the effectiveness of crude oil recirculation schemes after fluid volume design need to be directly and quantitatively understood. Summary of the Invention

[0004] This invention addresses the problem that the effect of improving crude oil reflux after optimizing the fluid volume of existing injection and production wells cannot be quickly, intuitively, and quantitatively evaluated. Starting from the impact of changes in water injection volume in injection wells and changes in production volume in production wells on the crude oil reflux capacity of reservoirs, this invention provides a method for evaluating the effect of improving crude oil reflux in water-driven reservoirs.

[0005] The technical solution of this invention is: a method for evaluating the effect of crude oil reflux in water-drive reservoirs on increasing production and injection, comprising the following steps:

[0006] Step 1: Calculate the physical property parameters of the mass point to the well point, including the distance r1 from the mass point to the injection well, the distance r2 from the mass point to the production well, the angle θ1 between the mass point and the injection well, and the angle θ2 between the mass point and the production well.

[0007] Step 2: Calculate the particle vector velocity v at time t0, the velocity vector angle θ of the particle at time t0, and the flow field velocity v2 of the particle returning under the pressure of the production well; where time t0 is the time when the particle does not flow.

[0008] Step 3: Calculate the position of the particle at time t1 using the distance r2 from the particle to the production well in Step 1, the particle vector velocity v at time t0 in Step 2, and the velocity vector angle θ of the particle at time t0; the time t1 is the time after the particle has flowed for time Δt, t1=t0+Δt;

[0009] Step 4: Using the flow field velocity v2 of the particle returning to the production well under the pressure in Step 2, calculate the original return time T of the particle to the production well at time t0 and the return time T' of the particle to the production well at time t1;

[0010] Step 5: Calculate the reflux capacity F of the particle to the production well using the initial reflux time T from the particle at time t0 and the reflux time T' from the particle at time t1 in Step 4. 回 (x,y,Δt);

[0011] (1) When the return flow capacity F 回 If (x,y,Δt)>0, then the reflux form of crude oil at the particle is reflux type;

[0012] (2) When the return flow capacity F 回 If (x,y,Δt)<0, then the reflux form of crude oil at the particle is extrapolated.

[0013] (3) When the return flow capacity F 回 If (x,y,Δt)=0, then the reflux form of crude oil at the particle is boundary type;

[0014] Step 6: After adjusting the injection and production fluid volume, calculate the effect ΔF on improving the mass point reflux capacity. 回 , ΔF 回 The higher the value of ΔF 回 A value greater than 0 indicates a better effect on the reflux capacity of crude oil after the injection and production volume is increased.

[0015] Preferably, the particle vector velocity v at time t0 is calculated using the following formula:

[0016]

[0017] The velocity vector angle θ of the particle at time t0 is calculated using the following formula:

[0018]

[0019] Where: v is the vector velocity of the particle; The average permeability of the particle to the injection well; The average permeability from the particle to the production well; The average thickness of the particle from the injection well; r1 is the average thickness from the mass point to the production well; r2 is the distance from the mass point to the injection well; P1 is the bottom pressure of the injection well; P2 is the bottom pressure of the production well; θ1 is the angle between the mass point and the injection well; θ2 is the angle between the mass point and the production well; μ o h is the viscosity of crude oil; h is the thickness at the location of the particle; r w V is the well radius; P is the formation pressure; θ is the velocity vector angle, v 1X Let v be the velocity vector of the particle in the X direction of the injection well. 1Y Let v be the velocity vector of the particle in the Y direction of the injection well. 2X Let v be the velocity vector of the particle in the X direction of the injection well. 2Y Let be the velocity vector of the particle in the Y direction of the injection well.

[0020] Preferably, the particle position at time t1 is specifically determined after the injection-production well fluid volume is adjusted, and the particle flows along the velocity vector angle θ with a vector velocity v. After time Δt, the particle position at t1 = t0 + Δt is calculated using the following formula:

[0021] x'=x+v·cosθ·Δt

[0022] y'=y+v·sinθ·Δt

[0023] Where (x,y) are the coordinates of the particle at time t0, and (x′,y′) are the coordinates of the particle at time t1.

[0024] Preferably, the original reflux time T from the particle at time t0 to the production well is calculated using the following formula:

[0025]

[0026] The reflux time T' from the particle to the production well at time t1 is calculated using the following formula:

[0027]

[0028] Where μ is the crude oil viscosity at time t0, μ' is the crude oil viscosity at time t1; h' is the thickness at the location of the particle at time t1; and r'2 is the distance from the particle to the production well at time t1. The average permeability of the particle to the production well at time t1; The average thickness of the particle from the production well at time t1.

[0029] Preferably, the reflux capacity F of the mass point to the production well 回(x, y, Δt), the calculation formula is as follows:

[0030]

[0031] Among them, F 回 (x,y,Δt) represents the reflux capacity of the particle to the production well at time t0.

[0032] Preferably, the improvement effect ΔF of the particle reflux capability 回 The calculation formula is as follows:

[0033]

[0034] Among them, F 回调 (x,y,Δt) represents the reflux capacity of crude oil after the injection and production well fluid volume is increased.

[0035] Compared with the prior art, the beneficial effects of this invention are as follows: Starting from the seepage velocity of fluid particles in the flow field, a calculation method is established based on the vector velocity of the fluid particles at time t0 and the position of the fluid particles at time t1 to determine the fluid volume of injection and production wells before and after the fluid volume adjustment. Starting from the influence of changes in water injection volume and production volume of injection wells on the oil reservoir's crude oil reflux capacity, the change in the flow field's crude oil reflux capacity and the ability to reflux to production wells is quantitatively characterized by the time of fluid reflux to production wells. A calculation method for the fluid volume reflux capacity of fluid particles before and after the fluid volume adjustment is established based on the fluid reflux direction time and fluid reflux capacity of fluid particles. Based on the calculation method for the improvement effect of fluid reflux capacity, the changes in the fluid reflux capacity of fluid particles before and after the fluid volume adjustment of injection wells and production wells are compared to evaluate the changes in crude oil reflux capacity under the increased production and injection of fluid volume adjustment in injection and production wells. This allows for a rapid and effective characterization of the improvement effect of crude oil reflux after the fluid volume adjustment of production wells, and achieves a rapid quantitative evaluation of the effect of fluid volume adjustment in injection and production wells. This invention further enriches the methods for evaluating flow fields, enabling rapid, effective, intuitive, and quantitative characterization of the effects of flow field changes caused by adjustments in injection and production well fluid volumes. It has significant practical value for the application of techniques for improving oil recovery through flow field adjustments in oilfields. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a flowchart illustrating the present invention;

[0038] Figure 2 This is a schematic diagram of the force analysis of any particle in this invention;

[0039] Figure 3 This is a permeability distribution diagram of the present invention;

[0040] Figure 4 This is a diagram showing the original reflux capacity of the particles in this invention;

[0041] Figure 5 This is a diagram illustrating the particle reflux capacity of the injection well after increased injection, as per the present invention.

[0042] Figure 6 This is a diagram illustrating the improved mass return capacity of the injection well after increased injection, as per the present invention.

[0043] Figure 7 This is a diagram illustrating the particle reflux capacity after fluid extraction from the production well according to the present invention.

[0044] Figure 8 This diagram illustrates the improved particle reflux capacity after fluid extraction from the production well, as presented in this invention. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] like Figure 1 As shown, this invention discloses a flowchart of a method for evaluating the effect of crude oil reflux in water-drive reservoirs to enhance production and injection. The method includes:

[0047] Step 1: Calculate the physical properties from the mass point to the well point

[0048] like Figure 2 As shown, for any particle with coordinates (x, y), the distance from the particle to the injection well is r1, the distance from the particle to the production well is r2, the angle between the particle and the injection well is θ1, the angle between the particle and the production well is θ2, and d is the distance from the injection well to the production well. The particle represents any point in the reservoir containing fluid.

[0049] Therefore, we can conclude that:

[0050]

[0051]

[0052]

[0053]

[0054] Where: x1 and y1 are the coordinates of the injection wells; x2 and y2 are the coordinates of the production wells.

[0055] The reservoir physical parameters between any point (x, y) and the injection and production wells are calculated using the following formula:

[0056] ① Average permeability from the mass point to the injection well and production well:

[0057] ② Average porosity between the mass point and the injection well and production well:

[0058] ③ Average thickness of the mass point between the injection well and the production well:

[0059] Where: i is the grid number between injection and production wells; n is the number of grids between injection and production wells; h i Let k be the thickness of the i-th grid; i φ is the permeability of the i-th grid. i Let i be the porosity of the i-th grid.

[0060] Step 2: Calculate the particle vector velocity at time t0

[0061] The velocity of a particle moving away from the injection well under pressure:

[0062] Therefore, we can conclude that:

[0063] The velocity vector of the particle in the X direction of the injection well:

[0064] The velocity vector of the particle in the Y direction of the injection well:

[0065] Where v1 is the velocity of the particle moving away from the injection well under the pressure, v 1X Let v be the velocity vector of the particle in the X direction of the injection well. 1Y Let be the velocity vector of the particle in the Y direction of the injection well. The average permeability of the particle to the injection well; The average thickness from the mass point to the injection well; P1 is the bottom hole pressure of the injection well; P is the formation pressure; r1 is the distance from the mass point to the injection well; μ o h is the viscosity of crude oil; h is the thickness at the location of the particle; r w Let θ be the well radius, and θ1 be the angle between the mass point and the injection well.

[0066] The reflux velocity of particles under production well pressure:

[0067] Therefore, we can conclude that:

[0068] The velocity vector of the particle in the X direction of the production well:

[0069] The velocity vector of the particle in the Y direction of the production well:

[0070] Where: v2 is the velocity of the particle moving away from the injection well under the pressure, v 2X Let v be the velocity vector of the particle in the X direction of the injection well. 2Y Let be the velocity vector of the particle in the Y direction of the injection well. The average permeability from the particle to the production well; r2 is the average thickness from the mass point to the production well; r2 is the distance from the mass point to the production well; P2 is the bottom hole pressure of the production well; θ2 is the angle between the mass point and the production well; μ o h is the viscosity of crude oil; h is the thickness at the location of the particle; r w denoted as well radius; P is the formation pressure.

[0071] From the above formulas (2) and (4), we can obtain the following method for calculating the resultant velocity of a particle in the Y direction of the regressing mainstream line:

[0072]

[0073] From the above formulas (1) and (3), we can obtain the following method for calculating the resultant velocity of a particle in the X direction of the main flow line:

[0074]

[0075] The vector velocity of any particle at time t0 can be established from the resultant velocity of the particle along the X and Y directions of the main flow line, specifically:

[0076] Depend on:

[0077]

[0078] We can obtain:

[0079]

[0080] Simultaneously, the direction of the velocity vector of any particle at time t0 can be calculated, specifically:

[0081]

[0082] From the above equation, the velocity vector angle of any particle at time t0 can be obtained, specifically:

[0083]

[0084] Step 3: Calculate the position of the particle at time t1

[0085] From step 1, we know that the coordinates of any particle at time t0 are (x, y), and its distance from the production well is r2. Then...

[0086]

[0087] After the injection and production well fluid volume is adjusted, the particle (x, y) flows along the velocity vector angle θ with a vector velocity v. After time Δt, the particle coordinates become (x′, y′), and the coordinate formula is as follows:

[0088] x'=x+v·cosθ·Δt

[0089] y'=y+v·sinθ·Δt

[0090] After the flow, the distance between the particle (x′, y′) and the production well becomes r'2 at t1=t0+Δt, specifically:

[0091]

[0092] Step 4: Calculate the particle recirculation time

[0093] From step 1, we know the coordinates of any particle at time t0 are (x, y), and the return velocity of the particle to the production well is as follows:

[0094]

[0095] Therefore, the return velocity of the flow point (x′, y′) to the production well is as follows:

[0096]

[0097] Where r'2 is the distance from the particle at position (x', y') to the production well at time t1; Let be the average permeability of the particle at position (x', y') to the production well at time t1; t1 represents the average thickness of the particle at position (x', y') to the production well; h' represents the thickness of the particle at position (x′, y′).

[0098] Based on the distance and reflux velocity of any particle (x, y) from the production well at time t0, the initial reflux time T from the particle to the production well can be calculated as follows:

[0099]

[0100] Therefore, after time Δt, at t1=t0+Δt, the return time T' of the flowed particles (x′,y′) to the production well is as follows:

[0101]

[0102] Where μ is the crude oil viscosity at time t0, μ' is the crude oil viscosity at time t1; h' is the thickness at the location of the particle at time t1; and r'2 is the distance from the particle to the production well at time t1. The average permeability of the particle to the production well at time t1; The average thickness of the particle from the production well at time t1.

[0103] Step 5: Calculate the particle recirculation capacity

[0104] In well groups in oilfield development, the remaining crude oil at different locations is affected by the injection and production fluid volumes. When the fluid volumes of injection wells and production wells are adjusted, it directly affects the displacement direction of the remaining crude oil, ultimately impacting the dynamic characteristics of the oil wells.

[0105] The return flow capacity of particle (x, y) to the production well is calculated using the following formula:

[0106]

[0107] Where q1 is the daily water injection volume of the injection well; q2 is the daily liquid production volume of the production well.

[0108] Substituting T and T' from step 4 into the above formula, we get:

[0109]

[0110] When the fluid volume in the injection well and production well is adjusted, the particle flows from coordinate (x,y) to coordinate (x′,y′). By comparing the return time T' of the particle to the production well after the flow with the original return time T, the positional distance relationship between the particle and the production well is determined; and the return capacity F is used to determine this relationship. 回 The magnitude of (x,y,Δt) is used to further evaluate the reflux pattern of crude oil at particle (x,y).

[0111] If a particle (x, y) flows to coordinate (x′, y′) after time Δt, the reflux of crude oil at that particle can be characterized by the following three scenarios:

[0112] (1) Recirculation type: When the recirculation capacity F 回 If (x,y,Δt)>0, then the reflux of crude oil at particle (x,y) is characterized as reflux type; when the reflux time T'<T, it indicates that the fluid particle (x,y) gradually approaches the production well after time Δt.

[0113] (2) Extrapolation type: When the return flow capacity F 回 If (x,y,Δt)<0, then the reflux pattern of crude oil at particle (x,y) is characterized as extrapolation type; when the reflux time T'>T, it indicates that the fluid particle (x,y) gradually moves away from the production well after Δt time.

[0114] (3) Transitional type: Dangdang return flow capability F 回 If (x,y,Δt)=0, then the reflux mode of crude oil at particle (x,y) is characterized as boundary type; when the reflux time T'=T, it means that no flow has occurred at fluid particle (x,y) after time Δt.

[0115] Step 6: Calculate the effect of improving the particle reflux capacity

[0116] (1) The bottom injection pressure of the injection well at the original injection volume q1 is (P1-P), which can be obtained according to the principle of planar radial flow:

[0117]

[0118] (2) The bottom hole flow pressure at the original production rate q2 of the production well is (P-P2), which can be obtained according to the principle of planar radial flow:

[0119]

[0120] (3) Calculate the reflux capacity of crude oil under the original injection-production well fluid volume. The calculation formula is as follows:

[0121]

[0122] Where: q1 is the daily water injection volume of the injection well; q2 is the daily liquid production volume of the production well.

[0123] (4) After adjusting the injection and production well fluid volume, calculate the crude oil reflux capacity F after the injection and production well fluid volume is increased. 回调 (x, y, Δt), the calculation formula is as follows:

[0124]

[0125] Wherein: F 回调 (x, y, Δt) represents the reflux capacity of the injection-production well after the fluid volume is increased; q 11 This refers to the daily water injection volume after adjusting the injection well fluid volume; q 21 This refers to the daily production volume after adjusting the production well fluid volume.

[0126] (5) The formula for calculating the improvement effect of crude oil reflux capacity after adjusting the injection and production fluid volume is as follows:

[0127]

[0128] To provide a more intuitive understanding of the application effect of the above-mentioned method for evaluating the production enhancement and injection of crude oil reflux in water-driven reservoirs, an example of the method is given below.

[0129] A mathematical model of a waterflood reservoir with one injection and one production cycle is established, assuming a reservoir thickness of 1m, a reservoir length of 300m, a reservoir width of 300m, and a permeability distribution as shown in the figure. Figure 3 As shown, the crude oil viscosity is 10 mPa·s, and the initial water injection volume of the injection well is 5 m³ / s. 3 / d, daily production of fluid from the production well is 5m³ 3 / d, the fluid volume after the well production increase is 10m³ 3 / d, the daily water injection volume after the well is increased is 10m³ 3 / d; The model is used to quantify the reflux effect after increased production and injection, and the results are as follows: Figure 4-8 As shown.

[0130] Figure 4 The initial water injection volume of the injection well is 5m 3 / d, the initial daily fluid production of the production well is 5m³ 3 The original reflux capacity of crude oil under the condition of / d; Figure 5 The water injection volume in the injection well was adjusted to 10m. 3 / d, daily production of fluid from the production well is 5m³ 3 The crude oil reflux capacity under the condition of / d; Figure 6 The water injection volume in the injection well was adjusted to 10m. 3 / d, daily production of fluid from the production well is 5m³ 3 The effect of improving crude oil reflux capacity under the condition of / d; by Figure 4-6 It can be seen that increasing the injection capacity of water injection wells increases the reflux capacity of crude oil in the mainstream area and reduces the reflux capacity of crude oil in the non-mainstream area, which is not conducive to further improving the crude oil recovery rate during the high water-cut period.

[0131] Figure 7 The water injection volume in the injection well is 5m 3 / d, the daily fluid production of the production well is adjusted to 10m³. 3 The crude oil reflux capacity under the condition of / d; Figure 8 The water injection volume in the injection well is 5m 3 / d, the daily fluid production of the production well is adjusted to 10m³. 3 The effect of improving the reflux capacity of crude oil under the condition of / d; by Figure 7-8 It can be seen that after the production wells are pumped out, the reflux capacity of crude oil in the mainstream area is reduced, while the reflux capacity of crude oil in the non-mainstream area is increased, which is conducive to further improving the crude oil recovery rate during the high water-cut period.

[0132] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for evaluating the effect of crude oil reflux in water-drive reservoirs on increasing production and injection, characterized in that: Includes the following steps: Step 1: Calculate the physical properties of the mass point from the well point, including the distance from the mass point to the injection well. Distance from the mass point to the production well The angle between the particle and the injection well The angle between the mass point and the production well ; Step 2: Calculate the particle vector velocity at time t0 The velocity vector angle of a particle at time t0 The flow field velocity of particles returning under the pressure of the production well The time t0 is the time when the particles have not flowed. Step 3: Calculate the distance from the particle in Step 1 to the production well. and the particle vector velocity at time t0 in step 2 The velocity vector angle of a particle at time t0 Calculate the position of the particle at time t1; where t1 is the elapsed time of the particle. After the flow, ; Step 4: Flow field velocity of the particles returning under the pressure of the production well in Step 2. Calculate the initial reflux time from the particle to the production well at time t0. and the return time from the particle to the production well at time t1 ; Step 5: Calculate the original reflux time from the particle at time t0 in Step 4 to the production well. and the return time from the particle to the production well at time t1 Calculate the return flow capacity from the mass point to the production well. ; (1) When the return flow capacity If 0, then the reflux form of crude oil at the particle is reflux type; (2) When the return flow capacity If 0, then the reflux form of crude oil at the particle is extrapolated. (3) When the return flow capacity If 0, then the reflux form of crude oil at the particle is boundary type; Step 6: After adjusting the injection and production fluid volume, calculate the effect of improving the mass point reflux capacity. , The higher the value and The better the reflux capacity of crude oil is improved after the injection volume is increased; The particle vector velocity at time t0 The calculation formula is as follows: The velocity vector angle of the particle at time t0 The calculation formula is as follows: ; Where: x and y are the coordinates of the particle at time t0; The vector velocity of the particle; The average permeability of the particle to the injection well; The average permeability from the particle to the production well; The average thickness of the particle from the injection well; The average thickness of the particle from the production well; This is the distance from the particle to the injection well; This is the distance from the particle to the production well; This refers to the bottom pressure of the injection well. For the bottom pressure of the production well; The angle between the particle and the injection well; The angle between the particle and the production well; Crude oil viscosity; The thickness at the location of the particle; The radius of the well; Formation pressure; For velocity vector angle, Let X be the velocity vector of the particle in the X direction of the injection well. Let be the velocity vector of the particle in the Y direction of the injection well. Let X be the velocity vector of the particle in the X direction of the injection well. Let be the velocity vector of the particle in the Y direction of the injection well; The return flow capacity of the particles to the production well The calculation formula is as follows: ; in, The return flow capacity of the particle to the production well at time t0. For the original time t0 Oil viscosity, The thickness at the location of the particle at time t1; The distance from the particle to the production well at time t1; The average permeability of the particle to the production well at time t1; The average thickness of the particle from the production well at time t1.

2. The method for evaluating the effect of crude oil reflux in water-drive reservoirs on increasing production and injection, as described in claim 1, is characterized in that: The particle position at time t1 is specifically defined as the position of the particle along the velocity vector angle after the injection / production well fluid volume is adjusted. With vector velocity Flowing, passing through time Then, in The formula for calculating the position of a particle is as follows: ; ; in: Let be the coordinates of the particle at time t1.

3. The method for evaluating the effect of crude oil reflux in water-drive reservoirs on increasing production and injection, as claimed in claim 1, is characterized in that: The original reflux time from the particle to the production well at time t0. The calculation formula is as follows: ; The return time of the particle to the production well at time t1 The calculation formula is as follows: ; in, Let t1 be the viscosity of the crude oil.

4. The method for evaluating the effect of crude oil reflux in water-drive reservoirs on increasing production and injection, as described in claim 1, is characterized in that: The effect of improving the particle reflux capacity The calculation formula is as follows: ; in, This refers to the reflux capacity of crude oil after the injection and production well fluid volume is increased.

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