Quantitative characterization method for reservoir permeability change after oil reservoir fluid injection development

Abstract

The invention discloses a quantitative characterization method for reservoir permeability change after oil reservoir fluid injection development. The quantitative characterization method comprises the following steps: step (1), establishing a relationship between the reservoir permeability of an oil reservoir and an average pore throat radius; (2) the average particle size of migration particles in a reservoir after oil reservoir fluid injection development is determined; (3) determining a reservoir permeability change turning value after oil reservoir fluid injection development; (4) when the original permeability of the reservoir is larger than the change turning value of the permeability of the reservoir after oil reservoir fluid injection development, the function relation between the change rate of the permeability of the reservoir after fluid injection development and the volume multiple of fluid injection pores is established; (5) when the original permeability of the reservoir is smaller than or equal to the change turning value of the permeability of the reservoir after fluid injection development of the oil reservoir, the function relation between the change rate of the permeability of the reservoir after fluid injection development and the volume multiple of fluid injection pores is established; and (6) the reservoir permeability after oil reservoir fluid injection development is quantitatively calculated.

Description

Technical Field

[0001] The invention belongs to the technical field of oil field development, and in particular relates to a quantitative characterization method for reservoir permeability changes after fluid injection development of an oil reservoir. Background Art

[0002] The study of reservoir permeability changes after fluid injection is an important research topic in fine reservoir description.

[0003] After long-term development with fluids such as water injection, steam injection, and chemical injection, the reservoir permeability of old oil fields in China such as Daqing and Shengli has changed significantly compared with the original permeability, which has greatly affected the distribution of remaining oil in the reservoir and has an important impact on the subsequent development effect of the oil field. Therefore, the quantitative characterization of the change in reservoir permeability after fluid injection development has important guiding significance for optimizing the development adjustment plan of old oil fields, improving the recovery rate of old oil fields, and improving the development effect of old oil fields.

[0004] At present, in terms of the change of reservoir permeability after water injection development of oil reservoirs, most people have mainly conducted some qualitative research to analyze the changing characteristics of reservoir permeability in different development periods.

[0005] Deng Yuzhen et al. published an article titled "Research on the Law of Changes in Reservoir Physical Characteristics during Water Injection Development" in "Oil and Gas Recovery Technology" in 1996. The article used data from coring wells to qualitatively understand the law of changes in reservoir permeability during water injection development and analyzed the reasons in stages by using statistical methods. Wu Suying published an article titled "Law of Changes in Reservoir Parameters after Long-term Water Injection and Its Impact on Development Effect" in "Daqing Petroleum Geology and Development" in 2006. The article analyzed the impact of reservoir parameter changes on development effects by studying the law of changes in formation particles, permeability, pore throat network and wettability in reservoirs at different water-containing stages. Xu Wanli et al. published an article titled "Research on Numerical Simulation Methods Based on Pore Network Simulation and Time-varying Reservoir Physical Properties" in "Petroleum Engineering Construction" in 2021. The article established a pore network model of a carbonate rock sample based on the pore network simulation method, and used the microscopic numerical simulation method to analyze the law of changes in reservoir wettability and permeability under different water-permeability multiples. The above literature believes that the reservoir permeability changes after water injection development, and the permeability has different changing patterns in different water-cut stages (initial, medium water-cut, high water-cut and extra-high water-cut stages). Especially in the medium-high water-cut and extra-high water-cut development stages, the reservoir permeability has changed significantly due to the continuous flushing of the reservoir by long-term injection of water. However, these articles only conduct qualitative and quantitative characterization of the changing pattern of reservoir permeability in stages, and do not conduct uninterrupted quantitative characterization of the whole process.

[0006] In order to accurately and quantitatively characterize the change of reservoir permeability after fluid injection, the establishment of a reasonable mathematical model is particularly important. To this end, we invented a quantitative characterization method for the change of reservoir permeability after fluid injection. Summary of the invention

[0007] Purpose of the present invention: In view of the above-mentioned deficiencies in the prior art, the present invention provides a method for quantitatively characterizing the change in reservoir permeability after fluid injection development.

[0008] Technical solution: A quantitative characterization method for reservoir permeability changes after fluid injection development, comprising the following steps:

[0009] Step (1), establishing the relationship between the reservoir permeability and the average pore throat radius;

[0010] Step (2), determining the average particle size of the particles migrating inside the reservoir after the reservoir is developed by fluid injection;

[0011] Step (3), determining the turning point value of the reservoir permeability change after the reservoir is developed by fluid injection;

[0012] Step (4), establishing a functional relationship between the rate of change of reservoir permeability after fluid injection development and the multiple of fluid injection pore volume when the original reservoir permeability is greater than the turning point value of the reservoir permeability change after fluid injection development;

[0013] Step (5), establishing a functional relationship between the rate of change of reservoir permeability after fluid injection development and the multiple of fluid injection pore volume when the original reservoir permeability is less than or equal to the turning point value of reservoir permeability change after fluid injection development;

[0014] Step (6), quantitatively calculating the reservoir permeability after the reservoir is developed by fluid injection.

[0015] Furthermore, step (1) includes:

[0016] (11) Obtaining a capillary pressure curve of a core of an oil reservoir;

[0017] (12) Using the experimental data of the capillary pressure curve of the reservoir core, the relationship between the reservoir permeability and the average pore throat radius is established:

[0018] K=f(R m ) (1)

[0019] Where:

[0020] K—reservoir permeability, 10 -3 μm 2 ;

[0021] R m —Average pore throat radius of the reservoir, μm.

[0022] Furthermore, the capillary pressure curve of the reservoir core in step (11) is obtained by any of the following methods:

[0023] a. Mercury intrusion method;

[0024] b. Centrifugation method.

[0025] Furthermore, in step (12), the specific expression of the relationship between the reservoir permeability and the average pore throat radius is as follows:

[0026]

[0027] Where:

[0028] K—reservoir permeability, 10 -3 μm 2 ;

[0029] R m —Average pore throat radius of the reservoir, μm;

[0030] a, b—undetermined coefficients (i.e., different constants obtained by fitting regression).

[0031] Furthermore, the specific steps of step (2) are:

[0032] Through the core injection fluid flushing experiment, the particle size of reservoir particles flushed out in the core outlet fluid was statistically analyzed to determine the average particle size of the particles migrating inside the reservoir after the reservoir was developed by fluid injection.

[0033] Furthermore, in step (3), the average particle size of the migrating particles inside the reservoir after the reservoir is developed by fluid injection obtained in step (2) is substituted into the relationship between the reservoir permeability and the average pore throat radius established in step (1), thereby obtaining the turning point value of the reservoir permeability change after the reservoir is developed by fluid injection.

[0034] Furthermore, in step (4), through the core injection fluid flushing experiment, when the original reservoir permeability is greater than the reservoir permeability turning value after the reservoir fluid injection development, the functional relationship between the reservoir permeability change rate after the fluid injection development and the fluid injection pore volume multiple is established, that is:

[0035] When K o >K t hour,

[0036] K r =f(PV) (2)

[0037] in

[0038]

[0039] Where:

[0040] K t -Reservoir permeability turning point after fluid injection development, 10 -3 μm 2 ;

[0041] K r —Rate of change of reservoir permeability after fluid injection development, dimensionless;

[0042] PV—fluid injection pore volume multiple, dimensionless;

[0043] K i —Reservoir permeability after fluid injection development, 10 -3 μm 2 ;

[0044] K o —Original reservoir permeability, 10 -3 μm 2 .

[0045] Furthermore, when the original reservoir permeability is greater than the reservoir permeability turning point after fluid injection development, the reservoir permeability change rate after fluid injection development K r The specific expression of the functional relationship between the fluid injection pore volume multiple PV is:

[0046] K r =e clnPV+d (2a)

[0047] Where:

[0048] K r —Rate of change of reservoir permeability after fluid injection development, dimensionless;

[0049] PV—fluid injection pore volume multiple, dimensionless;

[0050] c, d—Undetermined coefficients (i.e., different constants obtained by fitting regression).

[0051] Furthermore, in step (5), through the core injection fluid flushing experiment, when the original reservoir permeability is less than or equal to the reservoir permeability turning value after the reservoir fluid injection development, the functional relationship between the reservoir permeability change rate after the fluid injection development and the fluid injection pore volume multiple is established, that is:

[0052] When K o ≤K t hour,

[0053] K r =f(PV) (4)

[0054] in

[0055]

[0056] Where:

[0057] K t -Reservoir permeability turning point after reservoir fluid injection development, 10 -3 μm 2 ;

[0058] K r —Rate of change of reservoir permeability after fluid injection development, dimensionless;

[0059] PV—Fluid injection pore volume multiple, dimensionless.

[0060] K i —Reservoir permeability after fluid injection development, 10 -3 μm 2 ;

[0061] K o —Original reservoir permeability, 10 -3 μm 2 .

[0062] Furthermore, when the original reservoir permeability is less than or equal to the reservoir permeability turning value after fluid injection development, the specific expression of the functional relationship between the reservoir permeability change rate after fluid injection development and the fluid injection pore volume multiple is:

[0063] K r =e mlnPV+n (4a)

[0064] Where:

[0065] K r —Rate of change of reservoir permeability after fluid injection development, dimensionless;

[0066] PV—Fluid injection pore volume multiple, dimensionless.

[0067] m, n—undetermined coefficients (i.e., different constants obtained by fitting regression).

[0068] Further, in step (6), by respectively establishing the relationship between the change rate of reservoir permeability after fluid injection development and the multiple of the fluid injected pore volume when the original reservoir permeability is greater than the turning point of the reservoir permeability change, and

[0069] When the original permeability of the reservoir is less than or equal to the turning point of the reservoir permeability change, the relationship between the change rate of the reservoir permeability after fluid injection development and the multiple of the fluid injection pore volume can be used to quantitatively calculate the reservoir permeability after fluid injection development. The calculation formula is as follows

[0070] K i =Ko ×K r (5), where

[0071] K i —Reservoir permeability after fluid injection development, 10 -3 μm 2 ;

[0072] K o —Original reservoir permeability, 10 -3 μm 2 ;

[0073] K r -Rate of change in reservoir permeability after fluid injection development.

[0074] Beneficial effects: The method for quantitatively characterizing changes in reservoir permeability after fluid injection development disclosed in the present invention has the following beneficial effects:

[0075] 1. Based on the study of the dynamic changes in the permeability of different reservoirs as the degree of reservoir fluid injection development deepens, a mathematical model that can quantitatively describe and characterize the dynamic changes of the entire process of reservoir permeability is established, thereby achieving high-precision quantitative mathematical characterization of the entire process of reservoir permeability changes after reservoir fluid injection development;

[0076] 2. It lays the foundation for the derivation of reservoir engineering calculations, water drive oil theory and reservoir numerical simulation calculation methods, and can accurately predict the development effect and trend of reservoir injection fluid. It has important guiding significance for optimizing the development adjustment plan of old oil fields, improving the recovery rate of old oil fields, and improving the development effect of old oil fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 A flowchart of a method for quantitatively characterizing changes in reservoir permeability after fluid injection development disclosed in the present invention;

[0078] Figure 2 Schematic diagram of the relationship between the reservoir permeability and the average pore throat radius in Example 1.

[0079] Figure 3 It is a schematic diagram of the relationship between the change rate of reservoir permeability after fluid injection development and the multiple of fluid injection pore volume when the original permeability of the reservoir is greater than the turning point value of the reservoir permeability change in Example 1 of the present invention.

[0080] Figure 4 It is a schematic diagram of the relationship between the change rate of reservoir permeability after fluid injection development and the multiple of fluid injection pore volume when the original permeability of the reservoir is less than or equal to the turning value of the reservoir permeability change in Example 1 of the present invention. Specific implementation method:

[0081] The specific embodiments of the present invention are described in detail below.

[0082] At present, most people have mainly conducted some qualitative research on the change of reservoir permeability after water injection development of oil reservoirs, analyzing the characteristics of reservoir permeability changes in different development periods. However, these research and analysis methods only qualitatively characterize the law of reservoir permeability changes in stages, and do not conduct uninterrupted quantitative characterization of the entire process, and cannot accurately predict the effect and trend of oil reservoir fluid injection development.

[0083] In view of the above-mentioned deficiencies of the prior art, the present invention discloses a method for quantitatively characterizing the change in reservoir permeability after fluid injection development of an oil reservoir, comprising the following steps:

[0084] Step (1), establishing the relationship between the reservoir permeability and the average pore throat radius;

[0085] Step (2), determining the average particle size of the particles migrating inside the reservoir after the reservoir is developed by fluid injection;

[0086] Step (3), determining the turning point value of the reservoir permeability change after the reservoir is developed by fluid injection;

[0087] Step (4), establishing a functional relationship between the rate of change of reservoir permeability after fluid injection development and the multiple of fluid injection pore volume when the original reservoir permeability is greater than the turning point value of the reservoir permeability change after fluid injection development;

[0088] Step (5), establishing a functional relationship between the rate of change of reservoir permeability after fluid injection development and the multiple of fluid injection pore volume when the original reservoir permeability is less than or equal to the turning point value of reservoir permeability change after fluid injection development;

[0089] Step (6), quantitatively calculating the reservoir permeability after the reservoir is developed by fluid injection.

[0090] in:

[0091] The “original reservoir permeability” in step (3) is calculated using the core analysis data and is represented by Ko;

[0092] The core injection fluid flushing experiment in step (4) is mainly used to measure the relationship between the core permeability (reservoir permeability Ki after fluid injection development) and the pore volume multiple PV of the injected fluid, where:

[0093] Reservoir permeability change rate after fluid injection development K r = Reservoir permeability Ki after fluid injection development / reservoir original permeability Ko, Ko represents the original reservoir permeability.

[0094] This quantitative characterization method for reservoir permeability changes after fluid injection development quantitatively characterizes the changing laws of reservoir permeability in long-term fluid injection development reservoirs, laying a foundation for reservoir engineering calculations, water drive oil theory, and the derivation of reservoir numerical simulation calculation methods. It can accurately predict the effects and trends of reservoir fluid injection development, and has important guiding significance for optimizing the development adjustment plan of old oil fields, improving the recovery rate of old oil fields, and improving the development effect of old oil fields.

[0095] Example 1

[0096] The cores of Block A of Shengli Oilfield were analyzed to obtain a series of test data and to conduct quantitative characterization research on the changes in reservoir permeability after fluid injection development.

[0097] like Figure 1 As shown in the figure, the quantitative characterization method of reservoir permeability change after reservoir fluid injection development, the specific steps are as follows:

[0098] Step (1), establish the relationship between reservoir permeability and average pore throat radius:

[0099] (11) Obtaining a capillary pressure curve of a core of an oil reservoir;

[0100] (12) Using the experimental data of the capillary pressure curve of the reservoir core, the relationship between the reservoir permeability and the average pore throat radius is established.

[0101] Furthermore, the capillary pressure curve of the oil reservoir core in step (11) is obtained by mercury injection.

[0102] The unclassified test data of the capillary pressure curve of the reservoir core are shown in the following table:

[0103] Sample No. <![CDATA[Permeability, 10 -32 > Average pore throat radius, μm 7 2050 14.790 8 3670 16.650 16 401 4.246 20 1520 8.670 21 2490 12.890 28 1100 4.843 31 1510 5.060 32 1800 11.500 33 5100 19.070 39 300 4.614 52 5770 18.550 60 1650 7.989 70 5010 16.160 72 1340 10.430 74 8790 21.990 75 4540 13.000 76 1470 10.310 79 1350 9.519 83 1240 8.915 85 1690 8.222 87 908 7.346 88 1150 10.290

[0104] The above test data is entered into double natural logarithmic coordinates, as follows: Figure 2 As shown, it can be seen that the reservoir permeability and the average pore throat radius of the reservoir have a good linear relationship. Therefore, through fitting, the relationship between the reservoir permeability and the average pore throat radius of the reservoir is established:

[0105] K=e 1.5360lnRm+3.9658 R 2 =0.7864 (1a)

[0106] Where:

[0107] K-reservoir permeability, 10 -3 μm 2 ;

[0108] R m -Average pore throat radius of the reservoir, μm.

[0109] Step (2), determining the average particle size of the particles migrating inside the reservoir after the reservoir is developed by fluid injection:

[0110] Through the core water injection flushing experiment, the particle size of the reservoir particles flushed out in the core outlet fluid is statistically analyzed to determine the distribution range of the reservoir particle size flushed out, and then determine the average particle size of the reservoir particles flushed out after the reservoir is developed by fluid injection.

[0111] The average particle size of the particles flushed out of the reservoir after fluid injection development was determined by experimental measurement. m =1.306μm.

[0112] Step (3), determine the turning point value of reservoir permeability change after fluid injection development:

[0113] The average particle size r of the particles migrating inside the reservoir after the reservoir fluid injection development obtained in step (2) is m =1.306 μm Substitute into the relationship between reservoir permeability and average pore throat radius established in step (1) K = e 1.5360lnRm+3.9658 In the example, let R m =r m = 1.306 μm, that is, the turning point value K of the reservoir permeability change after the reservoir is developed by fluid injection t , that is, K t =79.5×10 -3 μm 2 .

[0114] In the reservoir, the reservoir permeability in different parts is different, and the corresponding average pore throat radius is also different. m Because of the continuous scouring, the average pore throat radius of the reservoir will become larger and larger, and the reservoir permeability will also become larger and larger; while the average particle size of the particles flushed out of the reservoir is less than or equal to r m Because the blockage of the particles in the previous reservoir makes the average pore throat radius of the reservoir smaller and smaller, the reservoir permeability will also become smaller and smaller. Therefore, there is a turning point value K of the reservoir permeability change corresponding to the average particle size of the reservoir particles in the reservoir. t .

[0115] Step (4), when the original permeability of the reservoir is greater than the turning point of the permeability change of the reservoir after the fluid injection development, the functional relationship between the change rate of the reservoir permeability after the fluid injection development and the multiple of the fluid injection pore volume is established:

[0116] Through core injection fluid flushing experiments, the original reservoir permeability K is established. o Greater than the reservoir permeability turning point K after fluid injection development t When the reservoir permeability change rate after fluid injection development is K rThe functional relationship between the fluid injection pore volume multiple PV is:

[0117] When K o >K t When the reservoir permeability change rate K r There is a linear relationship between the natural logarithm of the pore volume multiple PV of the fluid injection (e.g. Figure 3 As shown), we can get:

[0118] K r =e 0.0153lnPV+1.0128 R 2 =0.7051 (2a)

[0119] in

[0120]

[0121] Where:

[0122] K r —Rate of change of reservoir permeability after fluid injection development, dimensionless;

[0123] PV—fluid injection pore volume multiple, dimensionless;

[0124] K i —Reservoir permeability after fluid injection development, 10 -3 μm 2 ;

[0125] K o —Original reservoir permeability, 10 -3 μm 2 ;

[0126] Step (5), when the original permeability of the reservoir is less than or equal to the turning point of the permeability change of the reservoir after the fluid injection development, the functional relationship between the change rate of the reservoir permeability after the fluid injection development and the multiple of the fluid injection pore volume is established:

[0127] Through core injection fluid flushing experiments, the original reservoir permeability K is established. o Less than or equal to the turning value K t When the reservoir permeability change rate after fluid injection development is K r The functional relationship between the pore volume multiple PV of the fluid injection ( Figure 3 ):

[0128] When K o ≤K t When the reservoir permeability change turning point K after fluid injection development r There is also a linear relationship between the natural logarithm of the fluid injection pore volume multiple PV (such as Figure 4 As shown), we can get:

[0129] K r =e -0.1264lnPV+1.6122 R 2 =0.9014 (4a)

[0130] in

[0131]

[0132] (6) The original permeability K of the reservoir is established separately o Greater than and less than or equal to the turning point value K of reservoir permeability change t When the reservoir permeability change rate after fluid injection development is K r The relationship between the fluid injection pore volume multiple PV and the quantitative calculation of the reservoir permeability after fluid injection development is as follows:

[0133]

[0134] According to the above steps, the quantitative calculation and characterization of the permeability change of the reservoir developed by fluid injection in Block A of Shengli Oilfield was realized. Compared with the traditional method, the quantitative characterization method of the permeability change of the reservoir after fluid injection development can greatly improve the characterization accuracy of the permeability change of the reservoir developed by fluid injection, lay a foundation for the derivation of reservoir engineering calculation, water drive oil theory and reservoir numerical simulation calculation method, accurately predict the effect and trend of fluid injection development in the reservoir, and play an important guiding role in the development and production practice of oilfields.

[0135] Example 2

[0136] It is substantially the same as Example 1, except that the capillary pressure curve of the oil reservoir core in step (11) is obtained by centrifugation.

[0137] The above describes the embodiments of the present invention in detail. However, the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A quantitative characterization method for changes in reservoir permeability after fluid injection development, characterized in that: The following steps are involved: Step (1), establishing the relationship between the reservoir permeability and the average pore throat radius; Step (2), determining the average particle size of the particles migrating inside the reservoir after the reservoir is developed by fluid injection; Step (3), determining the turning point value of the reservoir permeability change after the reservoir is developed by fluid injection; Step (4), establishing a functional relationship between the rate of change of reservoir permeability after fluid injection development and the multiple of fluid injection pore volume when the original reservoir permeability is greater than the turning point value of the reservoir permeability change after fluid injection development; Step (5), establishing a functional relationship between the rate of change of reservoir permeability after fluid injection development and the multiple of fluid injection pore volume when the original reservoir permeability is less than or equal to the turning point value of reservoir permeability change after fluid injection development; Step (6), quantitatively calculating the reservoir permeability after the reservoir is developed by fluid injection.

2. The method for quantitatively characterizing the change in reservoir permeability after fluid injection development according to claim 1, characterized in that: The step (1) includes: (11) Obtaining a capillary pressure curve of a core of an oil reservoir; (12) Using the experimental data of the capillary pressure curve of the reservoir core, the relationship between the reservoir permeability and the average pore throat radius is established: K=f(R m ) (1) Where: K—reservoir permeability, 10 -3 μm 2 ; R m —Average pore throat radius of the reservoir, μm.

3. The method for quantitatively characterizing the change in reservoir permeability after fluid injection development according to claim 2, characterized in that: The capillary pressure curve of the reservoir core in step (11) is obtained by any of the following methods: a. Mercury intrusion method; b. Centrifugation method.

4. The method for quantitatively characterizing the change in reservoir permeability after fluid injection development according to claim 2, characterized in that: In step (12), the specific expression of the relationship between the reservoir permeability and the average pore throat radius is as follows: Where: K—reservoir permeability, 10 -3 μm 2 ; R m —Average pore throat radius of the reservoir, μm; a, b—coefficients to be determined.

5. The method for quantitatively characterizing the change in reservoir permeability after fluid injection development according to claim 1, characterized in that: The specific steps of step (2) are: Through the core injection fluid flushing experiment, the particle size of reservoir particles flushed out in the core outlet fluid was statistically analyzed to determine the average particle size of the particles migrating inside the reservoir after the reservoir was developed by fluid injection.

6. The method for quantitatively characterizing the change in reservoir permeability after fluid injection development according to claim 4, characterized in that: In step (3), the average particle size of the migrating particles inside the reservoir after the reservoir is developed by fluid injection obtained in step (2) is substituted into the relationship between the reservoir permeability and the average pore throat radius established in step (1), thereby obtaining the turning point value of the reservoir permeability change after the reservoir is developed by fluid injection.

7. The method for quantitatively characterizing the change in reservoir permeability after fluid injection development according to claim 1, characterized in that: In step (4), through the core injection fluid flushing experiment, when the original reservoir permeability is greater than the reservoir permeability turning value after the reservoir fluid injection development, the functional relationship between the reservoir permeability change rate after the fluid injection development and the fluid injection pore volume multiple is established, that is: When K o >K t hour, K r =f(PV) (2) in Where: K t -Reservoir permeability turning point after reservoir fluid injection development, 10 -3 μm 2 ; K r —Rate of change of reservoir permeability after fluid injection development, dimensionless; PV—fluid injection pore volume multiple, dimensionless; K i —Reservoir permeability after fluid injection development, 10 -3 μm 2 ; K o —Original reservoir permeability, 10 -3 μm 2 .

8. The method for quantitatively characterizing the change in reservoir permeability after fluid injection development according to claim 7, characterized in that: When the original permeability of the reservoir is greater than the turning point of the reservoir permeability after fluid injection development, the change rate of the reservoir permeability after fluid injection development K r The specific expression of the functional relationship between the fluid injection pore volume multiple PV is: K r =e cln PV+d (2a) Where: K r —Rate of change of reservoir permeability after fluid injection development, dimensionless; PV—fluid injection pore volume multiple, dimensionless; c, d—undetermined coefficients.

9. The method for quantitatively characterizing the change in reservoir permeability after fluid injection development according to claim 1, characterized in that: In step (5), through the core injection fluid flushing experiment, when the original reservoir permeability is less than or equal to the reservoir permeability turning value after the reservoir fluid injection development, the functional relationship between the reservoir permeability change rate after the fluid injection development and the fluid injection pore volume multiple is established, that is: When K o ≤K t hour, K r =f(PV) (4) in Where: K t -Reservoir permeability turning point after reservoir fluid injection development, 10 -3 μm 2 ; K r —Rate of change of reservoir permeability after fluid injection development, dimensionless; PV—fluid injection pore volume multiple, dimensionless; K i —Reservoir permeability after fluid injection development, 10 -3 μm 2 ; K o —Original reservoir permeability, 10 -3 μm 2 .

10. The method for quantitatively characterizing the change in reservoir permeability after fluid injection development according to claim 9, characterized in that: When the original reservoir permeability is less than or equal to the turning point of the reservoir permeability after fluid injection development, the specific expression of the functional relationship between the change rate of reservoir permeability after fluid injection development and the multiple of fluid injection pore volume is: K r =e mlnPV+n (4a) Where: K r —Rate of change of reservoir permeability after fluid injection development, dimensionless; PV—fluid injection pore volume multiple, dimensionless; m, n—coefficients to be determined.

11. The method for quantitatively characterizing the change in reservoir permeability after fluid injection development according to claim 1, characterized in that: In step (6), the relationship between the change rate of reservoir permeability after fluid injection development and the multiple of the fluid injected pore volume is established when the original permeability of the reservoir is greater than the turning point of the reservoir permeability change, and When the original permeability of the reservoir is less than or equal to the turning point of the reservoir permeability change, the relationship between the change rate of the reservoir permeability after fluid injection development and the multiple of the fluid injection pore volume can be used to quantitatively calculate the reservoir permeability after fluid injection development. The calculation formula is as follows K i =K o ×K r (5), where K i —Reservoir permeability after fluid injection development, 10 -3 μm 2 ; K o —Original reservoir permeability, 10 -3 μm 2 ; K r -Rate of change in reservoir permeability after fluid injection development.

Images