Control method for staged multi-cluster synchronous fracturing of horizontal well

Abstract

This invention discloses a method for controlling the simultaneous fracturing of multiple clusters in a horizontal well. The steps include: Step 1: acquiring logging data from multiple vertical wells in the target reservoir; Step 2: calculating the fracturing pressure using the P-wave transit time data of the vertical wells; Step 3: establishing a graph showing the relationship between natural gamma ray and fracturing pressure; Step 4: calculating the fracturing pressure of each perforation cluster in the horizontal well; Step 5: calculating the number of perforations in each perforation cluster. This method uses logging data from vertical wells in the target reservoir to establish a graph showing the relationship between natural gamma ray and fracturing pressure, overcoming the problem of limited data for horizontal wells and the inability to determine the number of perforations in multi-cluster fracturing. Using this method, the number of perforations in each perforation cluster can be determined, avoiding problems such as incomplete fracturing or uneven fracturing, increasing the fracturing volume, and improving post-fracturing productivity.

Description

Technical Field

[0001] This invention belongs to the field of reservoir stimulation technology and relates to a method for controlling the simultaneous fracturing of multiple clusters in a horizontal well segment. Background Technology

[0002] In recent years, through continuous research and development, the Changqing Oilfield has developed a multi-cluster fracturing technology for tight gas horizontal wells, primarily based on cementing, completion, bridge plug, and staged fracturing. This technology ensures effective isolation between stages and significantly increases production. Currently, the following problems still exist in multi-cluster fracturing of horizontal wells: ① Perforation clusters fail to fracture, fracture initiation is uneven, and gas production contribution rates vary significantly, greatly reducing the fracturing volume and severely impacting post-fracturing productivity; ② The reservoir exhibits strong heterogeneity, but horizontal well flow-limited fracturing still employs uniform perforation distribution, with limited research on optimizing the number of perforations; ③ Drilling data for horizontal wells is scarce, typically only natural gamma ray and gas logging data are available, making it difficult to determine the number of perforations for multi-cluster fracturing and lacking quantitative standards.

[0003] In his article "Optimization of Key Parameters for Multi-Cluster Fracturing in Tight Gas Horizontal Wells," Wu Bailie optimized the cluster spacing, number of perforations, and perforation location, but only considered the case where the maximum and minimum horizontal stress difference between the formations was 4 MPa. Zhou Zaile, in "Optimization of Perforation Parameters in Horizontal Well Flow-Limited Fracturing," used a pseudo-3D model to calculate the fracture mouth pressure of each fracture, and then optimized the number of perforations by combining the flow rate and pressure balance in flow-limited fracturing. However, solving the pseudo-3D model is difficult and challenging for large-scale field application. Zhang Yanjie, in his master's thesis "Research on Perforation Parameter Design Method in Flow-Limited Fracturing," established a fracture pressure prediction model to optimize the number of perforations. However, this model assumes homogeneous and isotropic reservoir conditions, while the Changqing tight gas reservoir is highly heterogeneous, making this model unsuitable. Summary of the Invention

[0004] The purpose of this invention is to provide a control method for simultaneous fracturing of multiple clusters in horizontal well sections, which solves the problem that it is difficult to improve the balanced expansion of perforation clusters in the prior art.

[0005] The technical solution adopted in this invention is a method for controlling the simultaneous fracturing of multiple clusters in a horizontal well, which is implemented according to the following steps:

[0006] Step 1: Obtain logging data from multiple vertical wells in the target reservoir;

[0007] Step 2: Calculate the fracturing pressure using the longitudinal wave transit time data of the vertical well;

[0008] Step 3: Establish a graph showing the relationship between natural gamma and crack initiation pressure.

[0009] When establishing the relationship chart between natural gamma and fracturing pressure, only the data on the location of the fracturing section should be used; after establishing the relationship chart between natural gamma and fracturing pressure, a linear relationship between natural gamma and fracturing pressure should be given.

[0010] Step 4: Calculate the fracturing pressure of each perforation cluster in the horizontal well.

[0011] When calculating the fracturing pressure of each perforation cluster in a horizontal well, the calculation is performed based on the natural gamma data of each perforation location, using the linear relationship between natural gamma and fracturing pressure given in step 3.

[0012] Step 5: Calculate the number of perforations in each perforation cluster.

[0013] The beneficial effects of this invention are that by using logging data from vertical wells in the target reservoir to establish a graph showing the relationship between natural gamma and fracturing pressure, it overcomes the problem of limited data in horizontal wells and the inability to determine the number of perforations in segmented multi-cluster fracturing. Using the method of this invention, the number of perforations in each perforation cluster can be determined, avoiding the problems of perforation clusters not fracturing or uneven fracturing, increasing the fracturing stimulation volume, and improving post-fracturing productivity. Attached Figure Description

[0014] Figure 1 This is a flowchart of an embodiment of the method of the present invention;

[0015] Figure 2 This is a graph showing the relationship between natural gamma and crack initiation pressure obtained in Example 1 of the method of the present invention;

[0016] Figure 3 This is a graph showing the relationship between natural gamma and crack initiation pressure obtained in Example 2 of the method of the present invention;

[0017] Figure 4 This is a graph showing the relationship between natural gamma and crack initiation pressure obtained in Example 3 of the method of the present invention;

[0018] Figure 5 This is a graph showing the relationship between natural gamma and crack initiation pressure obtained in Example 4 of the method of the present invention. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0020] Reference Figure 1 The present invention provides a method for controlling the simultaneous fracturing of multiple clusters in a horizontal well segment, which is implemented according to the following steps:

[0021] Step 1: Obtain logging data from multiple vertical wells in the target reservoir. The logging data for each vertical well includes the P-wave time difference Δt. p With natural gamma;

[0022] Step 2: Calculate the fracturing pressure using the longitudinal wave transit time data of the vertical well. The specific process is as follows:

[0023] 2.1) Calculate the transverse wave time difference using the following expression:

[0024]

[0025] Where, ρ b Density of rock is expressed in g / cm³. 3 ;Δt p This represents the longitudinal wave time difference, with units of μs / ft.

[0026] 2.2) Calculate the dynamic Poisson's ratio v d The expression is as follows:

[0027]

[0028] 2.3) Calculate the static Poisson's ratio v s The expression is: ν s =k ν ν d +d ν

[0029] Where, k ν d ν These represent rock mechanics conversion coefficients, both of which are dimensionless. The range of values ​​for these two coefficients is determined by experience or experimentation.

[0030] 2.4) Calculate the dynamic Young's modulus E d The expression is as follows:

[0031]

[0032] 2.5) Calculate the static Young's modulus E s The expression is: E s =k E E d +d E

[0033] Where, k E d E These represent rock mechanics conversion coefficients, which are dimensionless. The range of values ​​for these two coefficients is determined empirically or experimentally.

[0034] 2.6) Calculate the clay content V Sh The expression is as follows:

[0035]

[0036]

[0037] Among them, I shI represents the normalized natural gamma value, dimensionless. sh The value range is 0 to 1;

[0038] GCUR represents the Hillcatch coefficient, which is dimensionless and is taken as 3.7 for new strata and 2 for old strata.

[0039] GR stands for natural gamma, an abbreviation in Chinese. GR is obtained from step 1. max The maximum value in the GR data, GR min This is the minimum value in the GR data;

[0040] 2.7) Calculate the compressive strength S c The expression is: S c =0.0045E(1-V) sh +0.008EV sh

[0041] 2.8) Calculate the tensile strength S t The expression is:

[0042] 2.9) Calculate the triaxial geostress, the expression is as follows:

[0043]

[0044]

[0045]

[0046] Where α represents the Biot coefficient, and its value ranges from >0;

[0047] β and γ represent geological structural stress coefficients, and the values ​​of these two coefficients are greater than 0.

[0048] p p This represents formation pressure, and the unit is MPa.

[0049] σ v This represents the vertical stress, in MPa, with a value range > 0; σ h σ represents the minimum horizontal principal stress, in MPa, with a value range > 0; H This represents the maximum horizontal principal stress, in MPa, with a value range > 0.

[0050] H represents the depth of the formation, with a value greater than 0; ρ(h) represents the density of the rock in the formation at a certain depth, in g / cm³. 3 , with a value range > 0; v is Poisson's ratio, dimensionless, with a value range > 0;

[0051] 2.10) Calculate the crack initiation pressure P f The expression is: p f =3σh -σ H -αp p +S t

[0052] In step 2, vertical wells should be selected from the same reservoir in the target block, and the number of wells should be no less than three.

[0053] Step 3: Establish a graph showing the relationship between natural gamma and crack initiation pressure.

[0054] When establishing the relationship between natural gamma and fracturing pressure, only the data on the location of the fracturing segment should be used; after establishing the relationship between natural gamma and fracturing pressure, a linear relationship between natural gamma and fracturing pressure should be given.

[0055] Step 4: Calculate the fracturing pressure of each perforation cluster in the horizontal well.

[0056] When calculating the fracturing pressure of each perforation cluster in a horizontal well, the calculation is performed based on the natural gamma data of each perforation location, using the linear relationship between natural gamma and fracturing pressure given in step 3.

[0057] Step 5: Calculate the number of perforations in each perforation cluster. The specific process is as follows:

[0058] 5.1) Perform pressure balance calculation: (This means that there is a pressure balance relationship throughout the entire process, and the solution is obtained by solving the system of equations.)

[0059] p i +p fi =p i+1 +p fi+1 +p i～i+1 i = 1, 2, 3, ..., n-1

[0060] Where, p i p i+1 p represents the crack initiation pressure, measured in MPa. fi p fi+1 This indicates the frictional resistance of the orifice, measured in MPa; p i～i+1 This represents frictional resistance along the perforation path, measured in MPa; n represents the number of perforation clusters.

[0061] 5.2) Perform flow balance calculation: (This means that there is a flow balance relationship in the whole process, and the solution is obtained by solving the system of equations.)

[0062]

[0063] Among them, Q t —Total displacement during fracturing operations, in cubic meters (m³). 3 / min;

[0064] Qi —Flow rate in each crack, in cubic meters (m³) 3 / min;

[0065] 5.3) Calculate the frictional resistance along the path. The expression is:

[0066] Where λ represents the friction coefficient, which is greater than 0; l represents the friction length in meters; v represents the flow velocity of the liquid in the pipe in meters per second; D represents the pipe diameter in meters; and gravitational constant g = 9.8 N / kg.

[0067] 5.4) Calculate the number of perforations using the following expression:

[0068] Where, N pi Indicates the number of eyelets; C d C represents the flow resistance coefficient of the orifice. d The value range is 0 to 1;

[0069] In step 5, the limit cluster perforation is adopted, that is, the number of holes in a single cluster perforation is minimized as much as possible, in order to improve the uniformity of fluid distribution between clusters;

[0070] In step 5, uniform perforation is used for homogeneous fracturing sections with inter-cluster stress difference <1MPa; non-uniform perforation is used for heterogeneous fracturing sections with inter-cluster stress difference of 1 to 5MPa, and an iterative method is used to find a reasonable value for the number of perforations for each cluster.

[0071] In step 5, when determining the number of holes for each cluster, it is necessary to ensure that the ground construction pressure does not exceed the maximum ground construction pressure that the on-site equipment can provide, and that the hole friction can balance the stress difference between clusters, so as to promote the opening of the crack in the next cluster.

[0072] Example 1

[0073] This embodiment takes a horizontal well with 8 layers of multi-cluster fracturing and stimulation box as an example. In order to ensure that the perforation clusters in each fracturing section are uniformly initiated and the reservoir is fully stimulated, the number of perforations in the fracturing section is designed.

[0074] Reference Figure 1 The specific implementation steps of Embodiment 1 of the present invention are as follows:

[0075] Step 1: Obtain logging data from multiple vertical wells in the target reservoir. The logging data includes P-wave transit time and natural gamma.

[0076] Step 2: Calculate the fracturing pressure from the longitudinal wave transit time data of the vertical well. The specific process is as follows:

[0077] 2.1) Calculations were performed using data from the fracturing sections of 30 vertical wells in layer 8;

[0078] 2.2) The rock density is 2.8 g / cm³. 3 The Hillch coefficient GCUR is 3.7, the Biot coefficient α is 0.514, the geological tectonic stress coefficients β and γ are 0.451 and 0.577 respectively, and the rock mechanics conversion coefficient k... ν d ν k E With d E The values ​​are 0.323, 1.056, 0.872, and 0.121, respectively.

[0079] Step 3: Based on the natural gamma data of the vertical well and the calculated fracturing pressure, establish a graph showing the relationship between the natural gamma of the target reservoir and the fracturing pressure;

[0080] Reference Figure 2 This is a graph showing the relationship between natural gamma and fracture pressure established in Embodiment 1 of the present invention. The fitting data is large and the natural gamma has a wide distribution range, so the fitting results are representative. As can be seen from the fitting results, natural gamma and fracture pressure have a good linear correlation. As the natural gamma increases, the fracture initiation pressure continues to rise.

[0081] Step 4: Based on the established chart showing the relationship between the natural gamma ray and fracturing pressure of the target reservoir, calculate the fracturing pressure of each perforation cluster using the natural gamma ray data of each perforation cluster in the horizontal well. The calculation results are shown in Table 1 below.

[0082] Table 1. Calculation results of fracturing pressure for each perforation cluster

[0083]

[0084]

[0085] Step 5: Calculate the number of perforations in each perforation cluster. The specific process is as follows:

[0086] 5.1) The density of the fracturing fluid is 1.1 g / cm³. 3 The fracturing fluid viscosity is 30 mPa·s, the perforation orifice diameter is 0.97 cm, the flow coefficient is 0.82, the perforation density is 16 holes / m, and the casing diameter is 0.1143 m.

[0087] 5.2) For homogeneous fracturing sections with inter-cluster stress difference <1MPa, uniform perforation is adopted; for heterogeneous fracturing sections with inter-cluster stress difference 1~5MPa, non-uniform perforation is adopted, and an iterative method is used to find a reasonable value for the number of perforations in each cluster.

[0088] 5.3) The ground construction pressure shall not exceed 70 MPa, and the friction of the boreholes shall be able to balance the stress difference between clusters, thereby promoting the opening of the next cluster of cracks;

[0089] 5.4) Finally, the calculation results of the number of apertures for each cluster shown in Table 1 are obtained, which is the final result.

[0090] Example 2

[0091] This embodiment takes the segmented multi-cluster fracturing of the Taiyuan Formation in a horizontal well as an example. In order to ensure that the perforation clusters in each fracturing segment initiate fracturing evenly and that the reservoir is fully transformed, the number of perforations in the fracturing segment is designed.

[0092] Reference Figure 1 The specific implementation steps of embodiment 2 of the present invention are as follows:

[0093] Step 1: Obtain logging data from multiple vertical wells in the target reservoir. The logging data includes P-wave transit time and natural gamma.

[0094] Step 2: Calculate the fracturing pressure from the longitudinal wave transit time data of the vertical well. The specific process is as follows:

[0095] 2.1) Calculations were performed using data from the fracturing sections of 15 vertical wells in the Taiyuan Formation;

[0096] 2.2) The rock density is 2.8 g / cm³. 3 The Hillch coefficient GCUR is 3.7, the Biot coefficient α is 0.514, the geological tectonic stress coefficients β and γ are 0.449 and 0.560 respectively, and the rock mechanics conversion coefficient k... ν d ν k E With d E The values ​​are 0.30, 1.044, 0.859, and 0.142, respectively.

[0097] Step 3: Based on the natural gamma data of the vertical well and the calculated fracturing pressure, establish a graph showing the relationship between the natural gamma of the target reservoir and the fracturing pressure;

[0098] Reference Figure 3 This is a graph showing the relationship between natural gamma and fracture pressure established in this embodiment of the invention. The fitting data is large and the natural gamma has a wide distribution range, so the fitting results are representative. As can be seen from the fitting results, natural gamma and fracture pressure have a good linear correlation. As the natural gamma increases, the fracture initiation pressure continues to rise.

[0099] Step 4: Based on the established chart showing the relationship between the natural gamma of the target reservoir and the fracturing pressure, calculate the fracturing pressure of each perforation cluster using the natural gamma data of each perforation cluster in the horizontal well. The calculation results are shown in Table 2 below.

[0100] Table 2. Calculation results of fracturing pressure for each perforation cluster

[0101]

[0102] Step 5: Calculate the number of perforations in each perforation cluster. The specific process is as follows:

[0103] 5.1) The density of the fracturing fluid is 1.1 g / cm³. 3 The fracturing fluid viscosity is 30 mPa·s, the perforation orifice diameter is 0.97 cm, the flow coefficient is 0.82, the perforation density is 16 holes / m, and the casing diameter is 0.1143 m.

[0104] 5.2) For homogeneous fracturing sections with inter-cluster stress difference <1MPa, uniform perforation is adopted; for heterogeneous fracturing sections with inter-cluster stress difference 1~5MPa, non-uniform perforation is adopted, and an iterative method is used to find a reasonable value for the number of perforations in each cluster.

[0105] 5.3) The ground construction pressure shall not exceed 70 MPa, and the friction of the boreholes shall be able to balance the stress difference between clusters, thereby promoting the opening of the next cluster of cracks;

[0106] 5.4) Finally, the calculation results of the number of apertures for each cluster shown in Table 2 are obtained, which is the final result.

[0107] Example 3

[0108] This embodiment takes the multi-cluster fracturing of a horizontal well in the Shanxi Formation as an example. In order to ensure that the perforation clusters in each fracturing section initiate fracturing evenly and that the reservoir is fully transformed, the number of perforations in the fracturing section is designed.

[0109] Reference Figure 1 The specific implementation steps of embodiment 3 of the present invention are as follows:

[0110] Step 1: Obtain logging data from multiple vertical wells in the target reservoir. The logging data includes P-wave transit time and natural gamma.

[0111] Step 2: Calculate the fracturing pressure from the longitudinal wave transit time data of the vertical well. The specific process is as follows:

[0112] 2.1) Calculations were performed using data from the fracturing sections of 20 vertical wells in the Shanxi Formation;

[0113] 2.2) The rock density is 2.8 g / cm³. 3 The Hillch coefficient GCUR is 3.7, the Biot coefficient α is 0.514, the geological tectonic stress coefficients β and γ are 0.402 and 0.554 respectively, and the rock mechanics conversion coefficient k... ν d ν k E With d E The values ​​are 0.297, 1.142, 0.775, and 0.188, respectively.

[0114] Step 3: Based on the natural gamma data of the vertical well and the calculated fracturing pressure, establish a graph showing the relationship between the natural gamma of the target reservoir and the fracturing pressure;

[0115] Reference Figure 4This is a graph showing the relationship between natural gamma and fracture pressure established in this embodiment of the invention. The fitting data is large and the natural gamma has a wide distribution range, so the fitting results are representative. As can be seen from the fitting results, natural gamma and fracture pressure have a good linear correlation. As the natural gamma increases, the fracture initiation pressure continues to rise.

[0116] Step 4: Based on the established chart showing the relationship between the natural gamma of the target reservoir and the fracturing pressure, calculate the fracturing pressure of each perforation cluster using the natural gamma data of each perforation cluster in the horizontal well. The calculation results are shown in Table 3 below.

[0117] Table 3. Calculation results of fracturing pressure for each perforation cluster

[0118]

[0119] Step 5: Calculate the number of perforations in each perforation cluster. The specific process is as follows:

[0120] 5.1) The density of the fracturing fluid is 1.1 g / cm³. 3 The fracturing fluid viscosity is 30 mPa·s, the perforation orifice diameter is 0.97 cm, the flow coefficient is 0.82, the perforation density is 16 holes / m, and the casing diameter is 0.1143 m.

[0121] 5.2) For homogeneous fracturing sections with inter-cluster stress difference <1MPa, uniform perforation is adopted; for heterogeneous fracturing sections with inter-cluster stress difference 1~5MPa, non-uniform perforation is adopted, and an iterative method is used to find a reasonable value for the number of perforations in each cluster.

[0122] 5.3) The ground construction pressure shall not exceed 70 MPa, and the friction of the boreholes shall be able to balance the stress difference between clusters, thereby promoting the opening of the next cluster of cracks;

[0123] 5.4) Finally, the calculation results of the number of apertures for each cluster shown in Table 3 are obtained, which is the final result.

[0124] Example 4

[0125] This embodiment takes the segmented multi-cluster fracturing of the Majiagou Formation in a horizontal well as an example. In order to ensure that the perforation clusters in each fracturing segment initiate fracturing evenly and that the reservoir is fully transformed, the number of perforations in the fracturing segment is designed.

[0126] Reference Figure 1 The specific implementation steps of embodiment 4 of the present invention are as follows:

[0127] Step 1: Obtain logging data from multiple vertical wells in the target reservoir. The logging data includes P-wave transit time and natural gamma.

[0128] Step 2: Calculate the fracturing pressure from the longitudinal wave transit time data of the vertical well. The specific process is as follows:

[0129] 2.1) Calculations were performed using data from the fracturing sections of 20 vertical wells in the Majiagou Formation;

[0130] 2.2) The rock density is 2.8 g / cm³. 3 The Hillch coefficient GCUR is 3.7, the Biot coefficient α is 0.514, the geological tectonic stress coefficients β and γ are 0.435 and 0.561 respectively, and the rock mechanics conversion coefficient k... ν d ν k E With d E The values ​​are 0.309, 1.146, 0.792, and 0.205, respectively.

[0131] Step 3: Based on the natural gamma data of the vertical well and the calculated fracturing pressure, establish a graph showing the relationship between the natural gamma of the target reservoir and the fracturing pressure;

[0132] Reference Figure 5 This is a graph showing the relationship between natural gamma and fracture pressure established in this embodiment of the invention. The fitting data is large and the natural gamma has a wide distribution range, so the fitting results are representative. As can be seen from the fitting results, natural gamma and fracture pressure have a good linear correlation. As the natural gamma increases, the fracture initiation pressure continues to rise.

[0133] Step 4: Based on the established chart showing the relationship between the natural gamma ray and fracturing pressure of the target reservoir, calculate the fracturing pressure of each perforation cluster using the natural gamma ray data of each perforation cluster in the horizontal well. The calculation results are shown in Table 4 below.

[0134] Table 4. Calculation results of fracturing pressure for each perforation cluster

[0135]

[0136] Step 5: Calculate the number of perforations in each perforation cluster. The specific process is as follows:

[0137] 5.1) The density of the fracturing fluid is 1.1 g / cm³. 3 The fracturing fluid viscosity is 30 mPa·s, the perforation orifice diameter is 0.97 cm, the flow coefficient is 0.82, the perforation density is 16 holes / m, and the casing diameter is 0.1143 m.

[0138] 5.2) For homogeneous fracturing sections with inter-cluster stress difference <1MPa, uniform perforation is adopted; for heterogeneous fracturing sections with inter-cluster stress difference 1~5MPa, non-uniform perforation is adopted, and an iterative method is used to find a reasonable value for the number of perforations in each cluster.

[0139] 5.3) The ground construction pressure shall not exceed 70 MPa, and the friction of the boreholes shall be able to balance the stress difference between clusters, thereby promoting the opening of the next cluster of cracks;

[0140] 5.4) Finally, the calculation results of the number of apertures for each cluster shown in Table 4 are obtained, which is the final result.

Claims

1. A method for controlling the simultaneous fracturing of multiple clusters in a horizontal well, characterized in that, Follow these steps: Step 1: Obtain logging data from multiple vertical wells in the target reservoir; Step 2: Calculate the fracturing pressure using the longitudinal wave transit time data of the vertical well. The specific process is as follows: 2.1) Calculate the transverse wave time difference using the following expression: in, Density of rock is expressed in g / cm³. 3 ; This represents the P-wave time difference, in units of 1. ; 2.2) Calculate the dynamic Poisson's ratio v d The expression is as follows: 2.3) Calculate the static Poisson's ratio v s The expression is: in, , These represent rock mechanics conversion coefficients, both of which are dimensionless. The range of values ​​for these two coefficients is determined by experience or experimentation. 2.4) Calculate the dynamic Young's modulus E d The expression is as follows: 2.5) Calculate the static Young's modulus E s The expression is: in, , These represent rock mechanics conversion coefficients, which are dimensionless. The range of values ​​for these two coefficients is determined empirically or experimentally. 2.6) Calculate the clay content V Sh The expression is as follows: in, Represents the normalized natural gamma value, dimensionless. The value range is 0 to 1; GCUR denoted as the Hilch coefficient, dimensionless, taken as 3.7 for new strata and 2 for old strata; GR It's natural gamma, the abbreviation in Chinese. GR Obtained from step 1, GR max for GR The maximum value in the data, GR min for GR The minimum value in the data; 2.7) Calculate compressive strength S c The expression is: 2.8) Calculate tensile strength S t The expression is: 2.9) Calculate the triaxial geostress, the expression is as follows: in, This represents the Biot coefficient, with a value range > 0; , These represent geological structural stress coefficients, and the values ​​of these two coefficients are greater than 0. This represents formation pressure, and the unit is MPa. This represents vertical stress, in MPa, with a value range > 0; This represents the minimum horizontal principal stress, in MPa, with a value range >

0. This represents the maximum horizontal principal stress, in MPa, with a value range >

0. H Indicates the depth of the strata ， The range of values ​​is >0; This represents the density of rocks at a certain depth, expressed in g / cm³. 3 ， The range of values ​​is >0; v It is Poisson's ratio, dimensionless, and its value ranges > 0; 2.10) Calculate the crack initiation pressure P f The expression is: In step 2, vertical wells should be selected from the same reservoir in the target block, and the number of wells should be no less than three. Step 3: Establish a graph showing the relationship between natural gamma and crack initiation pressure. When establishing the relationship chart between natural gamma and fracturing pressure, only the data on the location of the fracturing section should be used; after establishing the relationship chart between natural gamma and fracturing pressure, a linear relationship between natural gamma and fracturing pressure should be given. Step 4: Calculate the fracturing pressure of each perforation cluster in the horizontal well. When calculating the fracturing pressure of each perforation cluster in a horizontal well, the calculation is performed based on the natural gamma data of each perforation location, using the linear relationship between natural gamma and fracturing pressure given in step 3. Step 5: Calculate the number of perforations in each perforation cluster. The specific process is as follows: 5.1) Perform pressure balance calculations: in, , This indicates the crack initiation pressure, measured in MPa. , This indicates the frictional resistance of the orifice, and the unit is MPa. This represents frictional resistance along the path, and the unit is MPa. n Indicates the number of perforation clusters; 5.2) Perform flow balance calculation: in, —Total displacement during fracturing operations, in units of ; —Flow rate in each crack, unit: ; 5.3) Calculate the frictional resistance along the path. The expression is: in, Indicates the friction coefficient. Greater than 0; This indicates the distance traveled, in meters (m). This indicates the flow velocity of the liquid inside the tube, and the unit is m / s; This indicates the diameter of the casing, in meters (m); the gravitational constant g = 9.8 N / kg. 5.4) Calculate the number of perforations using the following expression: in, Indicates the number of holes; C represents the flow resistance coefficient of the orifice. d The value range is 0 to 1.

2. The control method for simultaneous fracturing of multiple clusters in a horizontal well according to claim 1, characterized in that: The well logging data includes P-wave transit time. With natural gamma.

3. The control method for simultaneous fracturing of multiple clusters in a horizontal well according to claim 1, characterized in that: In step 5, the limit clustering perforation is used to reduce the number of holes in a single cluster perforation, thereby improving the uniformity of fluid distribution between clusters.

4. The control method for simultaneous fracturing of multiple clusters in a horizontal well according to claim 1, characterized in that: In step 5, uniform perforation is used for homogeneous fracturing sections with inter-cluster stress difference <1MPa; non-uniform perforation is used for heterogeneous fracturing sections with inter-cluster stress difference 1~5MPa, and an iterative method is used to find a reasonable value for the number of perforations for each cluster.

5. The control method for simultaneous fracturing of multiple clusters in a horizontal well according to claim 1, characterized in that: In step 5, when determining the number of holes in each cluster, the ground construction pressure does not exceed the maximum ground construction pressure that the on-site equipment can provide, and the friction of the holes can balance the stress difference between clusters, thus prompting the next cluster to open.

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