Heterogeneous combination flooding effect evaluation method

Abstract

The invention belongs to the technical field of oilfield development, and particularly relates to a heterogeneous combination flooding effect evaluation method, which comprises the following steps of: representing resistance coefficients by using the ratio of the pressure difference between two ends of an injection-production well to the difference between the injection speed of an injection end and the liquid production speed of an extraction end; after resistance coefficients are sorted, an accumulated resistance coefficient proportion Si and an accumulated well pair proportion Ti are calculated, Lorentz curves are drawn with the accumulated resistance coefficient proportion Si and the accumulated well pair proportion Ti as a vertical coordinate and a horizontal coordinate respectively, the displacement balance degree grade is determined through the Lorentz coefficients, scientific quantitative evaluation of the profile control and displacement effect is achieved, a basis is provided for selection of a profile control and displacement method, and the method has the advantages of being high in practicability and easy to popularize. And the oil field development efficiency can be improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oilfield development, and particularly relates to a method for evaluating the effect of a heterogeneous composite flooding. BACKGROUND

[0002] In the process of oilfield development, with the extension of the mining time, the water content of the reservoir is rising, and the recovery rate is facing challenges. As an important enhanced oil recovery technology, the heterogeneous composite flooding injects viscoelastic particles, polymers and the like into the reservoir, utilizes the migration, plugging and profile control effect thereof in the formation, improves the percolation condition of the reservoir, and thus improves the recovery rate of crude oil.

[0003] At present, the evaluation of the profile control effect of the heterogeneous composite flooding is mainly based on experience and simple production dynamic analysis, and lacks scientific and quantitative evaluation methods. The existing evaluation methods cannot accurately reflect the displacement balance degree of the reservoir in the profile control process, and cannot provide reliable basis for the selection and optimization of the profile control method. Specifically, the existing technology has the following deficiencies: lacking effective quantitative indicators to evaluate the displacement balance degree, and being difficult to scientifically judge the profile control effect; lacking targeted profile control scheme optimization methods for different displacement balance degree grades of well groups, resulting in unstable profile control effect; lacking clear standards and methods for verifying the profile control effect, and being difficult to accurately evaluate the effectiveness of the profile control measures.

[0004] Therefore, a scientific and quantitative method for evaluating the effect of the heterogeneous composite flooding is urgently needed to improve the accuracy and reliability of the profile control effect evaluation, provide basis for the selection and optimization of the profile control method, and thus improve the efficiency of oilfield development. SUMMARY

[0005] To solve the above technical problems, the present application provides a method for evaluating the effect of the heterogeneous composite flooding, which uses the ratio of the pressure difference between the injection well and the production well to the difference between the injection rate at the injection end and the liquid production rate at the production end to represent the resistance coefficient, calculates the resistance coefficients at the two ends of the injection well and the production well before and after the profile control respectively, sorts the resistance coefficients, and calculates the cumulative resistance coefficient proportion S i and the cumulative well pair proportion T i , respectively, to draw a Lorenz curve with the cumulative resistance coefficient proportion S i and the cumulative well pair proportion T i as the longitudinal coordinate and the horizontal coordinate, determine the displacement balance degree grade through the Lorenz coefficient, realize the scientific and quantitative evaluation of the profile control effect, and provide basis for the selection of the profile control method.

[0006] The technical problems solved by the present application are realized by the following technical solution: a method for evaluating the effect of the heterogeneous composite flooding, comprising the following steps: S1, collecting well group data Collect the production dynamic data at the two ends of the injection well and the production well in the well group before and after the profile control in an equal time sequence; S2, calculating the resistance coefficients between the injection end and the production end before and after the profile control The calculation formula of the resistance coefficient between the injection end and the production end is as follows: ; In the formula, P1 is the pressure of the injection end, Pa; P2 is the pressure of the production end, Pa; Q1 is the injection speed of the injection end, m 3 / s; Q2 is the liquid production speed of the production end, m 3 / / s; According to the production dynamic data of the injection end and the production end before the profile control, the injection speed of the injection end before the profile control, the liquid production speed of the production end, the pressure of the injection end and the pressure of the production end before the profile control are read, and the resistance coefficient between the injection end and the production end before the profile control is calculated. According to the production dynamic data of the injection end and the production end after the profile control, the injection speed of the injection end after the profile control, the liquid production speed of the production end, the pressure of the injection end and the pressure of the production end after the profile control are read, and the resistance coefficient between the injection end and the production end after the profile control is calculated. S3, calculating the Lorenz coefficient of the well group before and after the profile control According to the resistance coefficient between the injection end and the production end before and after the profile control, the Lorenz coefficient L of the well group before and after the profile control is calculated. S4, determining the displacement balance degree level The displacement balance degree level is determined by the Lorenz coefficient L, and the levels are divided as follows: L<0.3: first-level balance; 0.3≤L<0.5: second-level balance; 0.5≤L<0.7: third-level balance; 0.7≤L≤1: fourth-level balance; The profile control scheme is adjusted according to the balance degree level. The resistance coefficient formula of the application is directly derived from the transformation of the Darcy linear flow formula; the displacement balance degree before and after the profile control is judged by directly calculating the resistance coefficient, so as to evaluate the evaluation effect of the viscous non-homogeneous composite displacement profile control.

[0007] The application preferably further comprises S5, profile control effect evaluation, which is judged according to the size of the ratio M of the Lorenz coefficient before the profile control and the Lorenz coefficient after the profile control, and the main judgment levels are as follows: M<1: poor effect; 1≤M<2: medium effect; 2≤M<3: good effect; M≥3: good effect. The ratio of the Lorenz coefficient before the profile control to the Lorenz coefficient after the profile control is determined according to the value of the Lorenz coefficient before the profile control and the value of the Lorenz coefficient after the profile control. For example, when the value before the profile control is 0.7 and the value after the profile control is >0.7 (or =0.7), the Lorenz coefficient after the profile control is larger and is closer to 1, and is more uneven, so that it can be directly judged that the profile control effect is poor. At this time, the ratio of the Lorenz coefficient before the profile control to the Lorenz coefficient after the profile control is M≤1, and this type is classified as poor effect, so as to set different effect levels. The evaluation based on the profile control effect can verify the correctness of the initial diagnosis and the current development strategy.

[0008] Preferably, in step S4, the profile control scheme is adjusted according to the equalization level, and the adjustment specifically comprises: when the equalization level is level one, no profile control is needed; when the equalization level is level two, polymer profile control is adopted; when the equalization level is level three, particle plugging profile control is adopted; when the equalization level is level four, chemical agent and particle profile control are combined.

[0009] Preferably, in step S3, the specific calculation method of the Lorenz coefficient L of the well group before and after the profile control comprises the following steps: sorting the n resistance coefficient values C obtained before and after the profile control in ascending order to obtain a new sequence, and calculating the cumulative resistance coefficient proportion S according to the formula i , and calculating the cumulative well pair proportion T i ; taking the cumulative well pair proportion T i as the horizontal coordinate and the cumulative resistance coefficient proportion S i as the vertical coordinate to draw a Lorenz curve; calculating the area A between the Lorenz curve and the absolute equalization line y=x, and the triangular area B under the absolute equalization line, so as to obtain the Lorenz coefficient L; The formulas of the cumulative resistance coefficient proportion, the cumulative well pair proportion and the Lorenz coefficient are as follows:

[0010]

[0011]

[0012] In the formula, C i and C j are resistance coefficients, which are calculated according to the corresponding formula of the resistance coefficient C, i and j are subscripts, i and j are the arrangement numbers corresponding to the resistance coefficient C, j≤i; S i is the cumulative resistance coefficient proportion; and T iL is the Lorenz coefficient; n is related to the number of injection points and production points, and adjacent injection points and production points produce a resistance coefficient value.

[0013] Preferably, in step S1, the production dynamic data before and after the profile control and flooding are collected at an equal time sequence of 5-30 min / time.

[0014] Preferably, in step S4, the effect is verified by monitoring the maximum water cut reduction and the recovery ratio improvement after the profile control and flooding. Before the profile control and flooding, due to the strong reservoir heterogeneity (i.e., the balance degree is extremely low), the injected water is concentrated and flows in a few high-permeability channels, resulting in rapid water flooding of the production well and high water cut. After the profile control and flooding, the profile control agent preferentially enters the high-permeability channels, increasing the flow resistance. This causes the subsequent injection pressure to increase, and the injected fluid is forced to divert to the medium and low-permeability layers. This process directly improves the balance degree of the injection profile and the pressure field. Therefore, the production response of the profile control and flooding is that, with the effective control of the high-permeability channels, the proportion of crude oil from the low-permeability layers in the fluid produced from the oil well increases, and the proportion of water decreases, so that the “maximum water cut reduction” is observed. Therefore, the decrease of the water cut and the increase of the oil content are the most direct and sensitive evidence of the improvement of the balance degree of the underground flow field.

[0015] The inventive concept of the present application is that oilfield production is first water flooding, and then chemical flooding, particle profile control and flooding, or polymer profile control and flooding are used for yield increase when the water flooding effect is not good. The present application uses a two-dimensional flat plate model for simulation test, finds that the Lorenz coefficient can be calculated by using the resistance coefficients at the injection and production ends before and after the profile control and flooding, and the displacement balance degree grade is divided according to the size of the Lorenz coefficient. The Lorenz coefficient calculated before the profile control and flooding can be used to judge the displacement effect before the profile control and flooding (such as water flooding), and the profile control and flooding are needed when the displacement effect is not good. Then, the Lorenz coefficient after the profile control and flooding is calculated to obtain the displacement effect after the profile control and flooding, and the subsequent evaluation of the profile control and flooding effect is carried out. Through the above method, the present application summarizes the profile control and flooding schemes corresponding to different balance degree grades, and provides a basis for the selection and optimization of the profile control and flooding method in actual production.

[0016] In the present application, the Lorenz coefficient is a parameter reflecting the balance degree, the closer to 0, the more balanced the displacement, and the closer to 1, the less balanced the displacement. Therefore, according to the average idea, the present application divides the balance degree into four grades, and sets different profile control and flooding methods based on different balance degrees.

[0017] Compared with the prior art, the present application has the following beneficial effects: The present application collects the production dynamic data of the well group before and after the profile control and flooding, uses the ratio of the pressure difference between the injection and production wells to the difference between the injection speed at the injection end and the liquid production speed at the production end to represent the resistance coefficient; the resistance coefficients at the injection and production ends before and after the profile control and flooding are calculated respectively, the resistance coefficients are sorted, and the cumulative resistance coefficient proportion S is calculated. iAnd cumulative well pair ratio T i , and cumulative resistance coefficient ratio S i As the longitudinal coordinate, cumulative well pair ratio T i As the horizontal coordinate, draw the Lorenz curve, and determine the displacement balance degree grade according to the size of the Lorenz coefficient; the present application realizes the scientific evaluation of the profile control and displacement effect by quantifying the displacement balance degree, provides the basis for the selection of the profile control and displacement method, and helps to improve the oilfield development efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is the flow chart of the effect evaluation method of the heterogeneous composite flooding in the embodiment of the present application; Figure 2 It is a two-dimensional flat plate experimental model layout schematic diagram in the embodiment of the present application; Figure 3 It is a Lorenz curve drawing and area calculation schematic diagram in the embodiment of the present application. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings.

[0020] Term explanation: Primary balance, secondary balance, tertiary balance, quaternary balance: in the present application, the displacement balance degree between the injection end and the production end is divided into four levels according to the Lorenz coefficient L of the water drive or chemical drive balance degree, and the higher the level is, the worse the balance degree is.

[0021] As shown in Figure 1 , an effect evaluation method of heterogeneous composite flooding, which utilizes the Lorenz coefficient to classify the displacement balance degree, and evaluates the profile control and displacement effect according to the ratio of the Lorenz coefficients before and after the profile control and displacement, as shown in Figure 1 , the effect evaluation method of the heterogeneous composite flooding comprises the following steps: S1, collection of well group data In this embodiment, a two-dimensional flat plate model is selected for simulation test, and the two-dimensional flat plate model in this embodiment adopts an existing model, and an injection point and a plurality of production points are arranged on the model, and the two-dimensional flat plate model is provided with 25 injection-production ends, and the specific arrangement mode of the injection end and the production end is as shown in Figure 2 , an injection pump is used to inject water or displacement fluid into the injection end, a water drive or chemical drive experimental scene is simulated, and porosity and permeability data are collected.

[0022] The distance between the injection end and the production end is preferably 3-10 cm, the water cut of the well group before the profile control and displacement is greater than or equal to 70%, the porosity and other basic parameters are collected, and the production dynamic data before and after the profile control and displacement are collected at an equal time sequence frequency of 5-30 min / time, including injection speed, liquid production speed, injection-production pressure difference, etc.

[0023] The production dynamic data of the injection and production ends of the well groups before and after the profile control are collected in the equal time sequence, as shown in Table 1.

[0024] Table 1 simulation test data

[0025] In this embodiment, when the water content is 70%, the pressure values and flow rate values of the adjacent 4 injection and production ends in the upper left corner of the two-dimensional plate model (as shown in the middle rectangular frame) before the profile control are shown in Table 2 and Table 3: Figure 2 Table 2 pressure values (kPa) before profile control

[0026] Table 3 flow rate values (m 3 / s) before profile control

[0027] The pressure values and flow rate values of the adjacent 4 injection and production ends in the upper left corner of the two-dimensional plate model (as shown in the middle rectangular frame) after the profile control are shown in Table 4 and Table 5: Figure 2 Table 4 pressure values (kPa) after profile control

[0028] Table 5 flow rate values (m 3 / s) after profile control

[0029] S2, calculating the resistance coefficients before and after the profile control C1=(90-83) / (15-10.1)=1.43 is calculated according to the following formula, and the resistance coefficient values of the other groups are calculated as follows: 3.57, 1.89, 1.22. The calculation formula of the resistance coefficient between the injection end and the production end is as follows: ; In the formula, P1 is the pressure of the injection end, Pa; P2 is the pressure of the production end, Pa; Q1 is the injection rate of the injection end, m 3 / s; Q2 is the liquid production rate of the production end, m 3 / s.

[0030] Before the profile control, water flooding is carried out, and according to the production dynamic data of the injection and production ends before the profile control, the injection rate of the injection end before the profile control, the liquid production rate of the production end, the pressure of the injection and production ends before the profile control are read, and the resistance coefficient between the injection end and the production end before the profile control is calculated.

[0031] ​​The chemical flooding is selected, and according to the production dynamic data of the chemical flooding injection and production ends after the profile control and flooding, the injection speed of each injection end after the profile control and flooding, the liquid production speed of each production end, the pressure of each injection end and production end after the profile control and flooding are read, and the resistance coefficient between each injection end and production end after the profile control and flooding is calculated.

[0032] S3, calculating the Lorenz coefficient of the well group before and after the profile control and flooding According to the resistance coefficient between the injection end and the production end before and after the profile control and flooding, the Lorenz coefficient L of the well group before and after the profile control and flooding is calculated.

[0033] Before the profile control and flooding, S1=1.22 / (1.43+3.57+1.89+1.22)=0.15, and S2=0.33, S3=0.56, and S4=1 by analogy.

[0034] T1=i / n=1 / 4, T2=i / n=2 / 4, T3=i / n=3 / 4, and T4=i / n=1.

[0035] According to S i , T i , the Lorenz coefficient is calculated as L=0.5 / (1-0.378)=0.80 by drawing a graph.

[0036] The resistance coefficient value after the profile control and flooding is 0.45 by analogy.

[0037] S4, determining the displacement balance degree grade The displacement balance degree grade is determined by the Lorenz coefficient L, and the grade is divided as follows: L<0.3: first grade balance; 0.3≤L<0.5: second grade balance; 0.5≤L<0.7: third grade balance; 0.7≤L≤1: fourth grade balance; The profile control and flooding scheme is adjusted according to the balance degree grade. In step S4, the profile control and flooding scheme is adjusted according to the balance degree grade as follows: When the grade is the first grade balance, the water line advances uniformly, the water breakthrough is late, and the water cut rises slowly, so the profile control and flooding is not needed.

[0038] When the grade is the second grade balance, the water line advances unevenly, the single direction breakthrough appears, and the water cut rises quickly, so the polymer profile control and flooding is adopted.

[0039] When the grade is the third grade balance, the water cut rises quickly, and there may be obvious high permeability strips, large channels or even cracks, so the particle plugging profile control and flooding is adopted.

[0040] When the grade is the fourth grade balance, the joint chemical agent and particle profile control and flooding are adopted. In this embodiment, the water line advance is observed through the glass window of the two-dimensional flat model.

[0041] The equilibrium level before displacement is four according to L value = 0.80, and the equilibrium level after displacement is two according to L value = 0.45. In the embodiment, the displacement equilibrium degree is classified according to the Lorenz coefficient to determine the effect of the heterogeneous complex displacement; the greater the Lorenz coefficient, the more serious the channeling, and vice versa.

[0042] The effect evaluation method of the heterogeneous complex displacement further comprises S5, displacement effect evaluation, and the ratio M of the Lorenz coefficient before displacement to the Lorenz coefficient after displacement is used for judgment, and the main judgment levels are as follows: M < 1: poor effect; 1 ≤ M < 2: medium effect; 2 ≤ M < 3: good effect; M ≥ 3: good effect.

[0043] According to the numerical values of the Lorenz coefficients before and after displacement, M = 0.80 / 0.45 = 1.78, and the displacement effect is medium.

[0044] As shown in Figure 3 , in step S3, the specific calculation method of the Lorenz coefficient L of the well group before and after displacement is as follows: The n resistance coefficient values C obtained before and after displacement are sorted in ascending order to obtain a new sequence, and the cumulative resistance coefficient proportion S i and the cumulative well pair proportion T i are calculated according to the formula.

[0045] The cumulative well pair proportion T i is taken as the horizontal coordinate, the cumulative resistance coefficient proportion S i is taken as the vertical coordinate, and the Lorenz curve is drawn, specifically, a series of points (T1, S1) (T2, S2)... (T n , S n ) are drawn in a plane rectangular coordinate system, and then the points are connected in turn to obtain the Lorenz curve.

[0046] The area A between the Lorenz curve and the absolute equilibrium line y = x, and the triangular area B under the absolute equilibrium line are calculated, and in the embodiment, B = 0.5, which is used to calculate the Lorenz coefficient L; The formulas of the cumulative resistance coefficient proportion, the cumulative well pair proportion and the Lorenz coefficient are as follows:

[0047]

[0048]

[0049] In the formula, C i , Cj All are resistance coefficients, which are calculated by the corresponding formula of resistance coefficient C, i and j are subscripts, and i and j are the arrangement numbers corresponding to the resistance coefficient C, j≤i, such as: C1= represents the resistance coefficient between the first group of injection end and production end; S i is the cumulative resistance coefficient proportion; T i is the cumulative well pair proportion; L is the Lorenz coefficient; n is related to the number of injection points and production points, and adjacent injection points and production points produce a resistance coefficient value.

[0050] In step S1, the production dynamic data before and after the profile control and flooding is collected at an equal time sequence of 5-30 min / time.

[0051] In step S4, the effect is verified by monitoring the maximum water cut reduction amplitude and the recovery ratio improvement amplitude after the profile control and flooding. The specific determination standard is: the maximum water cut reduction amplitude Δfw≥5%; the recovery ratio improvement amplitude ΔEOR≥3%, and the profile control and flooding effect reaches the requirement when the above standards are reached.

[0052] The basic implementation process of the heterogeneous composite flooding effect evaluation method includes that one injection end corresponds to multiple production ends, and the resistance coefficient refers to the value between any pair of injection and production ends.

[0053] 1. According to the reference injection amount and the actual injection speed of each injection end, the liquid production speed of a certain production end, and the injection-production pressure difference, the resistance coefficient C between the well pair is calculated.

[0054] 2. The resistance coefficients C between all well pairs are arranged in ascending order, j and the cumulative resistance coefficient proportion S i is calculated. i

[0055] 3. Then, the Lorenz coefficient L of the well group is calculated according to S i and T i .

[0056] 4. The Lorenz coefficient L is classified according to the displacement balance degree.

[0057] 5. The profile control and flooding effect is evaluated according to the ratio of the Lorenz coefficients before and after displacement.

[0058] The injection speed before profile control and flooding of the injection end, the liquid production speed of the production end, and the injection speed of each injection end and the liquid production speed of the production end after profile control and flooding are collected and read at an equal time sequence, and the injection-production pressure difference before and after profile control and flooding is read.

[0059] ​​The parts not described in detail above are common knowledge for those skilled in the art, the present application is not limited to the above best mode, any person should know that the structural changes made under the inspiration of the present application, any technical solution with the same or similar to the present application, falls within the scope of the present application.

Claims

1. A method for evaluating the effect of a heterogeneous combination flooding, characterized in that, Comprising the following steps: S1, collection of well group data Collecting production performance data of injection and production ends in well group before and after profile control and flooding in equal time sequence; S2, calculating resistance coefficients before and after profile control and flooding The formula for calculating the resistance coefficient between the injection end and the production end is as follows: ； where P1 is the pressure at the injection end, Pa; P2 is the pressure at the production end, Pa; Q1 is the injection rate at the injection end, m 3 / s; Q2 is the fluid production rate at the production end, m 3 / s. According to the production performance data of the injection and production ends before profile control and flooding, read the injection rate of the injection end before profile control and flooding, the liquid production rate of the production end, read the pressure of each of the injection and production ends before profile control and flooding, and calculate the resistance coefficient between each injection end and the production end before profile control and flooding; According to the production performance data of the injection and production ends after profile control and flooding, read the injection rate of each injection end after profile control and flooding, the liquid production rate of each production end, read the pressure of each of the injection and production ends after profile control and flooding, and calculate the resistance coefficient between each injection end and the production end after profile control and flooding; S3, calculating the Lorenz coefficient of the well group before and after profile control and flooding According to the resistance coefficients between the injection end and the production end before and after profile control and flooding, respectively, calculate the Lorenz coefficient L of the well group before and after profile control and flooding; S4, determining the displacement balance degree level Determine the displacement balance degree level through the Lorenz coefficient L, and divide the level as follows: L<0.3: first-level balance; 0.3≤L<0.5: second-level balance; 0.5≤L<0.7: third-level balance; 0.7≤L≤1: fourth-level balance; Adjust the profile control and flooding scheme according to the balance degree level.

2. The method for evaluating the effect of the heterogeneous composite flooding according to claim 1, characterized in that: Also comprising S5, profile control and flooding effect evaluation, judge according to the ratio M of the Lorenz coefficient before profile control and flooding and the Lorenz coefficient after profile control and flooding, mainly judge the level as follows: M<1: poor effect; 1≤M<2: medium effect; 2≤M<3: good effect; M≥3: good effect.

3. The method for evaluating the effect of the heterogeneous composite flooding according to claim 1, characterized in that: In step S4, adjusting the profile control and flooding scheme according to the balance degree level is specifically: When the level is first-level balance, no profile control and flooding is needed; When the level is second-level balance, use polymer for profile control and flooding; When the level is third-level balance, use particles for profile control and flooding; When the level is fourth-level balance, use chemical agents and particles for profile control and flooding.

4. The method for evaluating the effect of the heterogeneous composite flooding according to claim 1, characterized in that, In step S3, the specific calculation method of the Lorenz coefficient L of the well group before and after profile control and flooding is as follows: Sort the n resistance coefficient values C obtained before and after the profile control in ascending order to obtain a new sequence, and calculate the cumulative resistance coefficient proportion S according to the formula i , cumulative well pair proportion T i ; Again, the cumulative well-to-well ratio T i is plotted as the abscissa, and the cumulative drag coefficient ratio S i is plotted as the ordinate, to draw a Lorenz curve; Calculate the area A between the Lorenz curve and the absolute balance line y=x, and the triangular area B under the absolute balance line, which is used to calculate the Lorenz coefficient L; The formula for calculating the cumulative resistance coefficient ratio, the cumulative well pair ratio and the Lorenz coefficient is as follows: In the formula, C i , C j are resistance coefficients, which are calculated according to the corresponding formula of the resistance coefficient C, i and j are subscripts, i and j are the arrangement serial numbers corresponding to the resistance coefficient C, j≤i; Si is the cumulative resistance coefficient proportion; T i L is the Lorenz coefficient; n is related to the number of injection points and production points, and adjacent injection points and production points produce a resistance coefficient value.

5. The method for evaluating the effect of the heterogeneous composite flooding according to claim 1, characterized in that: In step S1, collect the production performance data before and after profile control and flooding at a frequency of 5-30 min / time in equal time sequence.

6. The method for evaluating the effect of the heterogeneous composite flooding according to claim 1, characterized in that: In step S4, verify the effect by monitoring the maximum water cut reduction amplitude and the recovery rate improvement amplitude after profile control and flooding.

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