Classification and grading well selection method for improving single well productivity by changing development mode of horizontal well

Abstract

The invention discloses a classified and graded well selection method for improving single well productivity by changing a development mode of a horizontal well, which is specifically implemented according to the following steps: step 1, constructing a sample data set, and collecting basic data of geological parameters, engineering parameters and dynamic parameters of a sample; 2, according to the collected geological parameters, engineering parameters and dynamic parameters of the sample, determining main control factors influencing productivity in a horizontal well transformation development mode; 3, calculating a comprehensive evaluation index of the horizontal well according to the main control factors in the step 2; step 4, establishing a relation chart of the initial single well productivity of the sample and the comprehensive evaluation index by calculating the comprehensive evaluation index of the horizontal well; and 5, according to the single well productivity and comprehensive evaluation index relation chart, a classification and grading well selection standard is established. The classification and grading well selection method for improving the single well productivity through the horizontal well transformation development mode has few data point requirements, parameters are easy to obtain, initial single well productivity prediction of the horizontal well transformation development mode is effectively achieved, and area selection and well selection of the transformation development mode are effectively guided.

Description

Technical Field

[0001] The invention belongs to the technical field of efficient development of oil and gas fields, and relates to a classification and grading well selection method for improving single well productivity by changing the development mode of horizontal wells. Background Art

[0002] As an effective way to develop ultra-low permeability reservoirs, horizontal well hydraulic fracturing has been widely used in mine development at home and abroad. However, due to the poor physical properties of the reservoir, it is difficult to establish effective displacement in some ultra-low permeability reservoirs, and horizontal wells face the problem of low production and low speed development. In recent years, in order to significantly improve the oil production rate and recovery rate of the reservoir, the Yuan 284 area of ​​Changqing Oilfield has taken the lead in carrying out the transformation development mode test of horizontal well pre-pressure replenishment, fracturing energy enhancement, and post-pressure follow-up energy. The mine practice shows that after the transformation development mode test, the oil production rate has increased by 5 times, and the predicted recovery rate has increased by 12.0%, with obvious speed-up and production-enhancing effects. However, as the scale of the transformation development mode test of ultra-low permeability reservoirs gradually expands, the reservoir conditions it faces are worse, the length of horizontal wells is shorter, and the water drive law is more complicated. In the actual development process, the oil increase effect of horizontal wells after the transformation mode varies greatly, and the difficulty of well selection is increasing. Therefore, clarifying the main controlling factors for improving the production capacity of a single well by transforming the development mode and formulating well selection methods have become the key to improving the effect. The currently available reference well selection method is mainly the tight reservoir fracturing well selection method. This method is mainly based on big data analysis and requires a large number of data points. It has poor adaptability to well selection for horizontal well development mode transitions with fewer data points.

[0003] Therefore, in view of the current problems of few data points and great difficulty in well selection for horizontal well conversion development mode, the present invention establishes a comprehensive evaluation index calculation method based on weight analysis through sensitivity analysis, entropy weight algorithm, cluster analysis and other methods, and develops a relationship chart between the initial single well production capacity and the comprehensive evaluation index of the horizontal well conversion mode, thus forming a classified and graded well selection method for improving the single well production capacity when converting the development mode of horizontal wells. Summary of the invention

[0004] The purpose of the present invention is to provide a classification and grading well selection method for improving the single well productivity by changing the development mode of horizontal wells, thereby solving the problem of large differences in oil production increase effects after changing the development mode of horizontal wells.

[0005] The technical solution adopted by the present invention is:

[0006] The classification and grading well selection method for horizontal well transformation development mode to improve single well productivity is implemented in the following steps:

[0007] Step 1: Construct a sample data set and collect basic data of sample geological parameters, engineering parameters, and dynamic parameters;

[0008] Step 2: Determine the main controlling factors affecting the production capacity of the horizontal well development mode change based on the collected sample geological parameters, engineering parameters, and dynamic parameters;

[0009] Step 3, calculating the comprehensive evaluation index of the horizontal well according to the main controlling factors in step 2;

[0010] Step 4: Establish a relationship chart between the initial single well production capacity and the comprehensive evaluation index of the sample by calculating the comprehensive evaluation index of the horizontal well;

[0011] Step 5: Establish classification and grading well selection standards based on the relationship chart between single well productivity and comprehensive evaluation index.

[0012] The present invention is also characterized in that:

[0013] The specific method for constructing the sample data set in step 1 is: select the horizontal wells that have implemented the transformation of development mode and are currently producing stably as the sample data set, collect the geological parameters, engineering parameters, dynamic parameters of the samples and the basic data of the initial single well production capacity after the transformation, among which the geological parameters, engineering parameters and dynamic parameters are influencing factors, and the initial single well production capacity after the transformation of the horizontal well is the response value;

[0014] Geological parameters, including oil layer thickness h, porosity φ, permeability k, oil saturation S o ;

[0015] Engineering parameters, including horizontal section length L, sand addition amount S a , displacement D, total liquid volume entering the ground T, brittleness index I;

[0016] Dynamic parameters include the cumulative water injection volume W of the horizontal well and the remaining recoverable reserves R of the single well.

[0017] The specific method for determining the main controlling factors affecting the production capacity of the horizontal well development mode conversion in step 2 is: draw a scatter plot of each parameter in the sample data set and the initial single well production capacity of the sample, where the horizontal axis is the parameter value and the vertical axis is the initial single well production capacity of the sample, and determine the sensitivity factor based on the correlation analysis, that is, the main controlling factors affecting the production capacity are obtained.

[0018] The specific method for calculating the comprehensive evaluation index of horizontal wells in step 3 is:

[0019] Step 3.1, select data: Assume that a total of m horizontal wells are selected, n main controlling factors, X ij is the jth main controlling factor of the i-th horizontal well, where i = 1, 2, 3, ... m; j = 1, 2, 3, ... n;

[0020] Step 3.2: Data normalization: Normalize the data of each factor to obtain the dimensionless parameter X' ij :

[0021]

[0022] Step 3.3: Calculate the entropy value E of each main control factor using the entropy weight algorithm j :

[0023]

[0024] Step 3.4: Calculate the weight w of each main control factor j , the greater the weight, the greater the impact on horizontal wells.

[0025]

[0026] Step 3.5: Calculate the comprehensive evaluation index SSEV of any horizontal well according to the weight of each factor and the corresponding parameter value. i :

[0027]

[0028] The specific method for establishing the relationship chart between the initial single well production capacity of the sample and the comprehensive evaluation index in step 4 is: calculate the comprehensive evaluation index of any horizontal well in the sample set through step 3, and draw a scatter plot between the initial single well production capacity of all samples and the comprehensive evaluation index; fit the scatter plot by statistical regression method to obtain a fitting curve; perform intersection analysis on the fitting curve to obtain a relationship chart between the initial single well production capacity of the sample and the comprehensive evaluation index.

[0029] Perform intersection analysis on the fitting curve. The specific steps are as follows:

[0030] Step 4.1, connect the starting point and the end point of the fitting curve to obtain a straight line a;

[0031] Step 4.2, draw a tangent line to line a on the fitting curve to obtain line b;

[0032] Step 4.3, starting from the starting point of the fitting curve, draw a tangent line of the fitting curve to obtain straight line c;

[0033] Step 4.4, starting from the end point of the fitting curve, draw a tangent line of the fitting curve to obtain straight line d;

[0034] Step 4.5: Determine the intersection point a between straight line c and straight line b, and the intersection point b between straight line d and straight line b as classification intersection points.

[0035] The specific method for establishing the classification and grading well selection criteria in step 5 is as follows:

[0036] Step 5.1, according to the cluster analysis principle, obtain the classification interval based on the classification intersection point determined in step 4;

[0037] Step 5.2, determine the initial single well capacity classification corresponding to different comprehensive evaluation index ranges according to the classification interval, that is, obtain the classification and classification standard for horizontal well conversion development mode;

[0038] Step 5.3: For a certain horizontal well to be implemented, by calculating the comprehensive evaluation index of the horizontal well, the initial single well production capacity after the conversion can be predicted according to the classification and grading standards, thereby guiding the optimization of well selection for horizontal well conversion.

[0039] The beneficial effects of the present invention are as follows: the classification and grading well selection method for improving single well productivity in horizontal well transformation development mode requires few data points, is easy to obtain parameters, has sufficient theoretical basis, and has a simple calculation process. It can effectively realize the initial single well productivity prediction of horizontal well transformation development mode, and effectively guide the selection of areas and wells for transformation development mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a technical route flow chart of the classification and grading well selection method for improving the single well productivity by transforming the development mode of horizontal wells in the present invention;

[0041] Figure 2 It is a horizontal well production alignment curve diagram of a typical test area for transformation of development mode provided by the present invention according to the relevant technology;

[0042] Figure 3 It is a schematic diagram of the intersection analysis of the initial single well productivity and the comprehensive evaluation index of the classification and grading well selection method for improving the single well productivity in the horizontal well transformation development mode of the present invention;

[0043] Figure 4a is a graph showing the relationship between the initial single well production capacity and the oil layer thickness after the horizontal well conversion mode provided in Example 1 of the present invention according to the relevant technology;

[0044] Figure 4b is a graph showing the relationship between the initial single well production capacity and permeability after the horizontal well conversion method provided in Example 1 of the present invention according to the relevant technology;

[0045] Figure 4c is a graph showing the relationship between the initial single well production capacity and the horizontal section length after the horizontal well conversion mode provided in Example 1 of the present invention according to the relevant technology;

[0046] Figure 4d is a graph showing the relationship between the initial single well production capacity and the total amount of liquid entering the ground after the horizontal well conversion mode provided in Example 1 of the present invention according to the relevant technology;

[0047] Figure 5 is a relationship diagram between the initial single well production capacity and the comprehensive evaluation index after the horizontal well conversion mode provided by the relevant technology in Example 1 of the present invention;

[0048] Figure 6a It is a production alignment curve diagram of a typical horizontal well QP24 after well switching in Example 1 of the present invention;

[0049] Figure 6bIt is a production alignment curve diagram of the typical horizontal well CP49-10 after the well conversion mode in Example 1 of the present invention. DETAILED DESCRIPTION

[0050] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] Example 1

[0052] 1) Build a sample dataset,

[0053] As shown in Table 1, in the Yuan 284 development mode transformation industrialization test area, 43 horizontal wells that have implemented the transformation development mode and are in stable production were selected as sample data points to collect sample basic parameters and the initial single well production capacity after the transformation. The basic parameters mainly include oil layer thickness, oil saturation, horizontal section length, sand addition amount, displacement, total liquid volume entering the ground, and cumulative water injection volume.

[0054] Table 1 Basic parameter statistics of sample data set

[0055]

[0056] 2) Screening of the main controlling factors,

[0057] The sample data was used to conduct a sensitivity analysis of the single well productivity and different influencing factors in the initial stage of the development mode change, such as Figure 4a , Figure 4b , Figure 4c , Figure 4d As shown in the figure, according to the sensitivity analysis results, the main controlling factors affecting the implementation effect of the development mode change include: oil layer thickness h, oil saturation S o , horizontal section length L, sand addition amount S a , total liquid volume entering the ground T, brittleness index I, and cumulative water injection volume W corresponding to the horizontal well.

[0058] 3) Calculate the comprehensive evaluation index of horizontal wells,

[0059] According to the method in step 3, the data of the 7 main control factors of 43 horizontal wells were normalized to obtain dimensionless parameter values. On this basis, the entropy weight algorithm was used to calculate the weight of each factor, and the oil layer thickness h, oil saturation S o , horizontal section length L, sand addition amount S a The weights of total liquid volume T, brittleness index I, and cumulative water injection volume W for horizontal wells are 0.08, 0.08, 0.09, 0.16, 0.25, 0.17, and 0.17, respectively. The weights of each factor and the corresponding normalized parameter values ​​are summed up according to formula (5) to obtain the comprehensive evaluation index of each horizontal well, as shown in Table 2.

[0060] Table 2 Statistics of normalized dimensionless parameter values ​​of main control factors

[0061]

[0062] SSEV=0.08h+0.08S o +0.09L+0.16S a +0.25T+0.17I+0.17W (5)

[0063] 4) Establish classification and grading standards for well selection for horizontal well transformation development mode;

[0064] Draw a relationship diagram between the initial single-well production capacity and the comprehensive evaluation index after the development mode of 43 horizontal wells is changed, and determine the classification intersection point and classification interval according to the method in step 4, such as Figure 5 As shown in Table 3, the classification and grading well selection criteria for horizontal well conversion development mode are established according to the method in step 5.

[0065] Table 3 Classification and well selection criteria for horizontal well conversion development mode

[0066]

[0067]

[0068] 5) Typical well applications,

[0069] Two horizontal wells, QP24 and CP49-10, were selected to implement the development mode transformation test. The basic parameters of the two horizontal wells, such as geology and engineering, are shown in Table 4. Through calculation, it is found that the comprehensive evaluation index of QP24 well is 0.56, which is evaluated as Class II. The predicted initial single well production capacity is 5-10 tons / day, and the actual initial single well production capacity after the transformation is 10.4 tons / day. The CP49-10 well has a thin oil layer thickness, a short horizontal section, a low brittleness index, and a small cumulative water injection volume. The calculated comprehensive evaluation index is 0.16, which is evaluated as Class III. The predicted initial single well production capacity is less than 5 tons / day, and the initial single well production capacity after actual production is 4.5 tons / day. Figure 6a This is the production alignment curve of QP24 well after the conversion mode. Figure 6b The production curve of CP49-10 well after the conversion. The field production data of the two wells show that this method accurately predicts the single well production capacity in the early stage of the conversion development mode, thus effectively guiding the selection of wells for the conversion development mode and improving the success rate of the test.

[0070] Table 4 Basic parameter statistics of QP24 and CP49-10 wells

[0071]

[0072] Example 2

[0073] The classification and grading well selection method for horizontal well transformation development mode to improve single well productivity, such as Figure 1 , Figure 2 As shown, the specific implementation steps are as follows:

[0074] Step 1, construct a sample data set, and collect basic data of sample geological parameters, engineering parameters, and dynamic parameters; the specific method of constructing the sample data set is: select horizontal wells that have implemented the transformation of development methods and are currently producing stably as sample data sets, and collect the basic data of sample geological parameters, engineering parameters, dynamic parameters, and initial single well production capacity after the transformation, among which geological parameters, engineering parameters, and dynamic parameters are influencing factors, and the initial single well production capacity after the transformation of the horizontal well is the response value;

[0075] ① Geological parameters: including oil layer thickness h, porosity φ, permeability k, oil saturation S o ;

[0076] ② Engineering parameters: including horizontal section length L, sand addition amount S a , displacement D, total liquid volume entering the ground T, brittleness index I;

[0077] ③ Dynamic parameters: including the cumulative water injection volume W of the horizontal well and the remaining recoverable reserves R of a single well.

[0078] Step 2, determine the main controlling factors that affect the production capacity of horizontal wells when changing development modes based on the collected sample geological parameters, engineering parameters, and dynamic parameters; The specific method for determining the main controlling factors that affect the production capacity of horizontal wells when changing development modes is as follows: draw a scatter plot of each parameter in the sample data set and the initial single-well production capacity of the sample, where the horizontal axis is the parameter value and the vertical axis is the initial single-well production capacity of the sample, and determine the sensitivity factors based on correlation analysis, that is, obtain the main controlling factors that affect the production capacity.

[0079] Step 3: Calculate the comprehensive evaluation index of the horizontal well according to the main controlling factors in step 2; the specific method for calculating the comprehensive evaluation index of the horizontal well is:

[0080] Step 3.1, select data: Assume that a total of m horizontal wells are selected, n main controlling factors, X ij is the jth main controlling factor of the i-th horizontal well; where i = 1, 2, 3, ... m; j = 1, 2, 3, ... n;

[0081] Step 3.2: Data normalization: Normalize the data of each factor to obtain the dimensionless parameter X' ij :

[0082]

[0083] Step 3.3: Calculate the entropy value E of each main control factor using the entropy weight algorithm j :

[0084]

[0085] Step 3.4: Calculate the weight w of each main control factor j , the greater the weight, the greater the impact on horizontal wells:

[0086]

[0087] Step 3.5: Calculate the comprehensive evaluation index SSEV of any horizontal well according to the weight of each factor and the corresponding parameter value. i :

[0088]

[0089] Step 4. Establish a relationship chart between the initial single well production capacity of the sample and the comprehensive evaluation index by calculating the comprehensive evaluation index of the horizontal well; the specific method for establishing the relationship chart between the initial single well production capacity of the sample and the comprehensive evaluation index is as follows: calculate the comprehensive evaluation index of any horizontal well in the sample set by step 3, and draw a scatter plot between the initial single well production capacity of all samples and the comprehensive evaluation index; perform fitting regression on the scatter plot by statistical regression method to obtain a fitting curve; perform intersection analysis on the fitting curve to obtain a relationship chart between the initial single well production capacity of the sample and the comprehensive evaluation index.

[0090] Among them, Figure 3 As shown, the fitting curve is subjected to intersection analysis. The specific steps are as follows:

[0091] Step 4.1, connect the starting point and the end point of the fitting curve to obtain a straight line a;

[0092] Step 4.2, draw a tangent line to line a on the fitting curve to obtain line b;

[0093] Step 4.3, starting from the starting point of the fitting curve, draw a tangent line of the fitting curve to obtain straight line c;

[0094] Step 4.4, starting from the end point of the fitting curve, draw a tangent line of the fitting curve to obtain straight line d;

[0095] Step 4.5: Determine the intersection point a between straight line c and straight line b, and the intersection point b between straight line d and straight line b as classification intersection points.

[0096] Step 5: Establish classification and grading well selection standards based on the relationship chart between single well productivity and comprehensive evaluation index. The specific method for establishing classification and grading well selection standards is as follows:

[0097] Step 5.1, according to the cluster analysis principle, obtain the classification interval based on the classification intersection point determined in step 4;

[0098] Step 5.2, determine the initial single well capacity classification corresponding to different comprehensive evaluation index ranges according to the classification interval, that is, obtain the classification and classification standard for horizontal well conversion development mode;

[0099] Step 5.3: For a certain horizontal well to be implemented, by calculating the comprehensive evaluation index of the horizontal well, the initial single well production capacity after the conversion can be predicted according to the classification and grading standards, thereby guiding the optimization of well selection for horizontal well conversion.

[0100] Example 3

[0101] The classification and grading well selection method for horizontal well transformation development mode to improve single well productivity is implemented in the following steps:

[0102] Step 1: Construct a sample data set and collect basic data of sample geological parameters, engineering parameters, and dynamic parameters. The specific method of constructing the sample data set is: select horizontal wells that have implemented the transformation of development methods and are currently producing stably as sample data sets, collect the basic data of sample geological parameters, engineering parameters, dynamic parameters, and initial single well production capacity after the transformation, among which geological parameters, engineering parameters, and dynamic parameters are influencing factors, and the initial single well production capacity after the transformation of the horizontal well is the response value;

[0103] ① Geological parameters: including oil layer thickness h, porosity φ, permeability k, oil saturation S o ;

[0104] ② Engineering parameters: including horizontal section length L, sand addition amount S a , displacement D, total liquid volume entering the ground T, brittleness index I;

[0105] ③ Dynamic parameters: including the corresponding water injection volume W of horizontal wells and the remaining recoverable reserves R of single wells.

[0106] Step 2, determine the main controlling factors that affect the production capacity of horizontal wells in the transformation of development mode based on the collected sample geological parameters, engineering parameters, and dynamic parameters; the specific method for determining the main controlling factors of the production capacity of horizontal wells in the transformation of development mode is: draw a scatter plot of each parameter in the sample data set and the initial single well production capacity of the sample, where the horizontal axis is the parameter value and the vertical axis is the initial single well production capacity of the sample, and determine the sensitivity factors based on the correlation analysis, that is, the main controlling factors affecting the production capacity are obtained.

[0107] Step 3, calculating the comprehensive evaluation index of the horizontal well according to the main controlling factors in step 2;

[0108] Step 4: Establish a relationship chart between the initial single well production capacity and the comprehensive evaluation index of the sample by calculating the comprehensive evaluation index of the horizontal well;

[0109] Step 5: Establish classification and grading well selection standards based on the relationship chart between single well productivity and comprehensive evaluation index.

[0110] Example 4

[0111] The classification and grading well selection method for horizontal well transformation development mode to improve single well productivity is implemented in the following steps:

[0112] Step 1: Construct a sample data set and collect basic data of sample geological parameters, engineering parameters, and dynamic parameters;

[0113] Step 2: Determine the main controlling factors affecting the production capacity of the horizontal well development mode change based on the collected sample geological parameters, engineering parameters, and dynamic parameters;

[0114] Step 3: Calculate the comprehensive evaluation index of the horizontal well according to the main controlling factors in step 2; the specific method for calculating the comprehensive evaluation index of the horizontal well is:

[0115] Step 3.1, select data: Assume that a total of m horizontal wells are selected, n main controlling factors, X ij is the jth main controlling factor of the i-th horizontal well; where i = 1, 2, 3, …m; j = 1, 2, 3, …n.

[0116] Step 3.2: Data normalization: Normalize the data of each factor to obtain the dimensionless parameter X' ij :

[0117]

[0118] Step 3.3: Calculate the entropy value E of each main control factor using the entropy weight algorithm j :

[0119]

[0120] Step 3.4: Calculate the weight w of each main control factor j : The greater the weight, the greater the impact on horizontal wells:

[0121]

[0122] Step 3.5: Calculate the comprehensive evaluation index SSEV of any horizontal well according to the weight of each factor and the corresponding parameter value. i :

[0123]

[0124] Step 4. Establish a relationship chart between the initial single well production capacity of the sample and the comprehensive evaluation index by calculating the comprehensive evaluation index of the horizontal well; the specific method for establishing the relationship chart between the initial single well production capacity of the sample and the comprehensive evaluation index is as follows: calculate the comprehensive evaluation index of any horizontal well in the sample set by step 3, and draw a scatter plot between the initial single well production capacity of all samples and the comprehensive evaluation index; perform fitting regression on the scatter plot by statistical regression method to obtain a fitting curve; perform intersection analysis on the fitting curve to obtain a relationship chart between the initial single well production capacity of the sample and the comprehensive evaluation index.

[0125] Perform intersection analysis on the fitting curve. The specific steps are as follows:

[0126] Step 4.1, connect the starting point and the end point of the fitting curve to obtain a straight line a;

[0127] Step 4.2, draw a tangent line to line a on the fitting curve to obtain line b;

[0128] Step 4.3, starting from the starting point of the fitting curve, draw a tangent line of the fitting curve to obtain straight line c;

[0129] Step 4.4, starting from the end point of the fitting curve, draw a tangent line of the fitting curve to obtain straight line d;

[0130] Step 4.5: Determine the intersection point a between straight line c and straight line b, and the intersection point b between straight line d and straight line b as classification intersection points.

[0131] Step 5: Establish classification and grading well selection standards based on the relationship chart between single well productivity and comprehensive evaluation index. The specific method for establishing classification and grading well selection standards is as follows:

[0132] Step 5.1, according to the cluster analysis principle, obtain the classification interval based on the classification intersection point determined in step 4;

[0133] Step 5.2, determine the initial single well capacity classification corresponding to different comprehensive evaluation index ranges according to the classification interval, that is, obtain the classification and classification standard for horizontal well conversion development mode;

[0134] Step 5.3: For a certain horizontal well to be implemented, by calculating the comprehensive evaluation index of the horizontal well, the initial single well production capacity after the conversion can be predicted according to the classification and grading standards, thereby guiding the optimization of well selection for horizontal well conversion.

Claims

1. A classification and grading well selection method for improving single well productivity by changing the development mode of horizontal wells, characterized in that: Follow the steps below to implement it: Step 1: Construct a sample data set and collect basic data of sample geological parameters, engineering parameters, and dynamic parameters; Step 2: Determine the main controlling factors affecting the production capacity of the horizontal well development mode change based on the collected sample geological parameters, engineering parameters, and dynamic parameters; Step 3, calculating the comprehensive evaluation index of the horizontal well according to the main controlling factors described in step 2; Step 4: Establish a relationship chart between the initial single well production capacity and the comprehensive evaluation index of the sample by calculating the comprehensive evaluation index of the horizontal well; Step 5: Establish classification and grading well selection standards based on the relationship chart between single well productivity and comprehensive evaluation index.

2. The classification and grading well selection method for improving single well productivity by converting the development mode of horizontal wells according to claim 1 is characterized in that: The specific method for constructing the sample data set in step 1 is: select the horizontal wells that have implemented the transformation of development mode and are currently producing stably as the sample data set, collect the geological parameters, engineering parameters, dynamic parameters of the samples and the basic data of the initial single well production capacity after the transformation, wherein the geological parameters, engineering parameters and dynamic parameters are influencing factors, and the initial single well production capacity after the transformation of the horizontal well is the response value; The geological parameters include oil layer thickness h, porosity φ, permeability k, oil saturation S o ; The engineering parameters include: horizontal section length L, sand addition amount S a , displacement D, total liquid volume entering the ground T, brittleness index I; The dynamic parameters include the cumulative water injection volume W corresponding to the horizontal well and the remaining recoverable reserves R of the single well.

3. The classification and grading well selection method for improving single well productivity by converting the development mode of horizontal wells according to claim 1 is characterized in that: The specific method for determining the main controlling factors affecting the production capacity of the horizontal well development mode conversion in step 2 is: draw a scatter plot of each parameter in the sample data set and the initial single well production capacity of the sample, where the horizontal axis is the parameter value and the vertical axis is the initial single well production capacity of the sample, and determine the sensitivity factor based on the correlation analysis, that is, the main controlling factors affecting the production capacity are obtained.

4. The classification and grading well selection method for improving single well productivity by changing the development mode of horizontal wells according to claim 1 is characterized in that: The specific method for calculating the comprehensive evaluation index of horizontal wells in step 3 is: Step 3.1, select data: Assume that a total of m horizontal wells are selected, n main controlling factors, X ij is the jth main controlling factor of the i-th horizontal well, where i = 1, 2, 3, ... m; j = 1, 2, 3, ... n; Step 3.2: Data normalization: Normalize the data of each factor to obtain the dimensionless parameter X' ij : Step 3.3: Calculate the entropy value E of each main control factor using the entropy weight algorithm j : Step 3.4: Calculate the weight w of each main control factor j , the greater the weight, the greater the impact on horizontal wells. Step 3.5: Calculate the comprehensive evaluation index SSEV of any horizontal well according to the weight of each factor and the corresponding parameter value. i :

5. The classification and grading well selection method for improving single well productivity by converting the development mode of horizontal wells according to claim 1 is characterized in that: The specific method for establishing the relationship chart between the initial single well production capacity of the sample and the comprehensive evaluation index in step 4 is: calculate the comprehensive evaluation index of any horizontal well in the sample set through step 3, and draw a scatter plot between the initial single well production capacity of all samples and the comprehensive evaluation index; perform fitting regression on the scatter plot through the statistical regression method to obtain a fitting curve; perform intersection analysis on the fitting curve to obtain a relationship chart between the initial single well production capacity of the sample and the comprehensive evaluation index.

6. The classification and grading well selection method for improving single well productivity by converting the development mode of horizontal wells according to claim 5 is characterized in that: The specific steps of performing intersection analysis on the fitting curve are as follows: Step 4.1, connect the starting point and the end point of the fitting curve to obtain a straight line a; Step 4.2, draw a tangent line to line a on the fitting curve to obtain line b; Step 4.3, starting from the starting point of the fitting curve, draw a tangent line of the fitting curve to obtain straight line c; Step 4.4, starting from the end point of the fitting curve, draw a tangent line of the fitting curve to obtain straight line d; Step 4.5: Determine the intersection point a between straight line c and straight line b, and the intersection point b between straight line d and straight line b as classification intersection points.

7. The classification and grading well selection method for improving single well productivity by converting the development mode of horizontal wells according to claim 1 is characterized in that: The specific method for establishing the classification and grading well selection criteria in step 5 is as follows: Step 5.1, according to the cluster analysis principle, obtain the classification interval based on the classification intersection point determined in step 4; Step 5.2, determine the initial single well capacity classification corresponding to different comprehensive evaluation index ranges according to the classification interval, that is, obtain the classification and classification standard for horizontal well conversion development mode; Step 5.3: For a certain horizontal well to be implemented, by calculating the comprehensive evaluation index of the horizontal well, the initial single well production capacity after the conversion can be predicted according to the classification and grading standards, thereby guiding the optimization of well selection for horizontal well conversion.

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