Dynamic correction method for closing pressure in fracturing process and related equipment

Abstract

The invention discloses a dynamic correction method for closing pressure in the fracturing process and related equipment, and belongs to the technical field of oil and gas field development. The method comprises the steps that firstly, geomechanical parameters of a target well are obtained, then the minimum principal stress and the minimum principal stress increase value of a fractured reservoir are obtained through calculation according to the geomechanical parameters, and the minimum principal stress increase value is caused by the pore elastic effect in the fracturing construction process; and finally, the effective closing pressure of the fracture is obtained based on the minimum principal stress and the minimum principal stress added value of the fractured reservoir, and dynamic correction of the closing pressure is achieved. According to the method, the minimum principal stress increase caused by the pore elastic effect in the fracturing process is considered, the predicted closing pressure is closer to the closing pressure obtained by testing fracturing or post-fracturing analysis, the problem of inaccurate prediction of the closing pressure before fracturing is solved, the dynamic correction of the closing pressure in the fracturing process can be realized, and the accuracy of the fracturing process is improved. Therefore, construction parameters are optimized, and the construction effect is improved.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas field development technology, specifically relating to the prediction of closure pressure during fracturing; and particularly to a dynamic correction method and related equipment for closure pressure during fracturing. Background Technology

[0002] Closure pressure refers to the average pressure exerted on the fracture surface by the fluid within the smallest existing fracture opening. As a hydraulic fracturing parameter, closure pressure is one of the main bases for selecting proppant type, particle size, deployment concentration, and determining conductivity. It helps ensure the correct use of proppant and optimize the effectiveness of fracturing operations. Therefore, obtaining closure pressure is crucial for fracturing construction or fracturing evaluation.

[0003] Closing pressure is typically obtained through field measurements. Common methods include stepped injection testing, backflow testing, equilibrium testing, and pressure drop curve analysis, but these methods are too costly. Closing pressure can also be calculated during fracturing operations using instantaneous pump stop pressure and sudden changes in flow rate; however, these methods are essentially post-fracturing calculations. Currently, the closing pressure referenced in fracturing construction parameter design is generally historical test data or pre-fracturing prediction data. Inaccurate prediction data will directly affect the construction results. It is generally believed that the minimum principal stress is the closing pressure. Therefore, predicting the closing pressure involves calculating the minimum principal stress. Currently, the main methods for calculating the minimum principal stress include the pore elastic horizontal strain model, triaxial strain model, Mohr-Coulomb stress model, uniaxial strain empirical relation, Huang's empirical relation, combined spring empirical relation, differential empirical relation, and Georg's geostress empirical relation, all of which are calculated using geomechanical parameters. However, during fracturing, fracturing fluid leaks into the formation, causing an increase in pore pressure near the fracture and resulting in formation swelling, which in turn increases the minimum principal stress in that area. During the shut-in and flowback process, the fracture remains open due to the proppant, so this stress increase persists. Therefore, it is evident that the minimum principal stress predicted using the above method based on geomechanical parameters still differs from the fracture closure pressure calculated through analysis, testing, and fracturing operations.

[0004] Therefore, it can be seen that the existing prediction methods fail to consider the increase in minimum principal stress caused by the elastic effect of pores, resulting in inaccurate prediction of the pre-compression closure pressure. Summary of the Invention

[0005] The purpose of this invention is to provide a dynamic correction method and related equipment for the closure pressure during fracturing, so as to solve the technical problem that the prediction of the closure pressure before fracturing is inaccurate because the existing prediction method does not take into account the increase in minimum principal stress caused by the elastic effect of pores.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for dynamically correcting the closure pressure during fracturing includes: Obtain the geomechanical parameters of the target well; The minimum principal stress and the increase in minimum principal stress of the fracturing reservoir were calculated based on geomechanical parameters, wherein the increase in minimum principal stress was generated by the pore elastic effect during the fracturing operation. The effective closure pressure of the fracture is obtained based on the minimum principal stress and the increase of the minimum principal stress in the fracturing reservoir, so as to achieve dynamic correction of the closure pressure.

[0007] Furthermore, the geomechanical parameters include rock density, formation water density, Young's modulus, Poisson's ratio, effective stress coefficient, tectonic stress coefficient in the direction of maximum horizontal principal stress, tectonic stress coefficient in the direction of minimum horizontal principal stress, and porosity coefficient.

[0008] Furthermore, the minimum principal stress of the fracturing reservoir was calculated based on geomechanical parameters. s h It is calculated based on the tectonic stress coefficient in the direction of maximum horizontal principal stress and the tectonic stress coefficient in the direction of minimum horizontal principal stress; The specific formula is as follows:

[0009] In the formula: K H The tectonic stress coefficient in the direction of the maximum horizontal principal stress is dimensionless. K h The tectonic stress coefficient in the direction of the minimum horizontal principal stress is dimensionless. E Young's modulus, GPa; y wo Poisson's ratio is dimensionless. α The effective stress coefficient is dimensionless. s v The vertical stress is measured in MPa. P p Formation pressure, MPa;

[0010] In the formula: s v The vertical stress is measured in MPa. r Density of rock, g / cm³ 3 ; h Let m be the depth. H ρ is the reservoir depth, m; g is the gravitational acceleration, m / s². 2 ;

[0011] In the formula: P p Formation pressure, MPa; r 水 Density of formation water, g / cm³ 3 ; h Depth, m; g, acceleration due to gravity, m / s² 2 .

[0012] Furthermore, the minimum principal stress increase Δ was calculated based on geomechanical parameters. s It was calculated based on the bottom hole flowing pressure, the original formation pressure, and the porosity coefficient. The specific formula is as follows:

[0013] In the formula: P wf The bottom hole flowing pressure is in MPa. P 0 represents the original formation pressure, in MPa; β The porosity coefficient is dimensionless. u Poisson's ratio is dimensionless.

[0014] In the formula: P wf The bottom hole flowing pressure is in MPa. P t The wellhead oil pressure, in MPa, is obtained from construction data. P hi The pressure is the liquid column pressure, in MPa. P fl The theoretical value of wellbore fracturing fluid friction at maximum displacement, in MPa;

[0015] In the formula: P hi The pressure is the liquid column pressure, in MPa. r i The density of the liquid is kg / m³. 3 ; h i The height of the liquid column is m; g is the acceleration due to gravity, m / s². 2 ; i i The wellbore inclination angle corresponding to the liquid, in rad; P fl =σP f0 In the formula: P flThe theoretical value of wellbore fracturing fluid friction at maximum displacement, in MPa; s The drag reduction ratio is dimensionless. P f0 The theoretical value of wellbore friction under maximum discharge rate, in MPa;

[0016] In the formula: s The drag reduction ratio is dimensionless. d The diameter of the wellbore is in mm; Q max The maximum displacement during construction, m 3 / min; G Thickener concentration, kg / m³ 3 ;

[0017] In the formula: P f0 The theoretical value of wellbore friction under maximum discharge rate, in MPa; d The diameter of the wellbore is in mm; Q max The maximum displacement during construction, m 3 / min.

[0018] Furthermore, the effective closing pressure of the crack P s Calculated based on the minimum principal stress and the increase in minimum principal stress during fracturing; The specific formula is as follows: P s = s h + Δ s In the formula: s h For the minimum principal stress, MPa ;Δ s This is the increase in minimum principal stress. MPa .

[0019] Furthermore, it also includes: after obtaining the geomechanical parameters of the target well, performing data preprocessing on the geomechanical parameters; the data preprocessing methods include: data cleaning and data normalization.

[0020] A dynamic correction system for closure pressure during fracturing, comprising the steps of implementing the aforementioned dynamic correction method for closure pressure during fracturing, including: The data acquisition module is used to obtain the geomechanical parameters of the target well; The stress calculation module is used to calculate the minimum principal stress and the minimum principal stress increase value of the fracturing reservoir based on geomechanical parameters, wherein the minimum principal stress increase value is generated by the pore elastic effect during the fracturing operation. The pressure correction module is used to obtain the effective closure pressure of the fracture based on the minimum principal stress and the minimum principal stress increase value of the fracturing reservoir, so as to achieve dynamic correction of the closure pressure.

[0021] An apparatus comprising: Memory, used to store computer programs; A processor is used to implement the steps of the above-described dynamic correction method for closure pressure during fracturing when executing the computer program.

[0022] A computer-readable storage medium storing a computer program, which, when executed by a processor, is used to implement the steps of the above-described method for dynamically correcting the closing pressure during fracturing.

[0023] A computer program product includes a computer program / instructions that, when executed by a processor, implement the steps of the dynamic correction method for closure pressure during fracturing described above.

[0024] Compared with the prior art, the present invention has the following beneficial effects: This invention also provides a dynamic correction method for closure pressure during fracturing. This method first obtains the geomechanical parameters of the target well, then calculates the minimum principal stress and the increase in minimum principal stress of the fracturing reservoir based on these parameters. The increase in minimum principal stress is caused by the pore elasticity effect during fracturing. Finally, the effective closure pressure of the fracture is obtained based on the minimum principal stress and the increase in minimum principal stress, thus achieving dynamic correction of the closure pressure. This method considers the increase in minimum principal stress caused by the pore elasticity effect during fracturing, and the predicted closure pressure is closer to the closure pressure obtained from test fracturing or post-fracturing analysis. It overcomes the problem of inaccurate prediction of closure pressure before fracturing and can achieve dynamic correction of closure pressure during fracturing, thereby optimizing construction parameters and improving construction results.

[0025] Preferably, in this invention, the geomechanical parameters include rock density, formation water density, Young's modulus, Poisson's ratio, effective stress coefficient, tectonic stress coefficient in the direction of maximum horizontal principal stress, tectonic stress coefficient in the direction of minimum horizontal principal stress, and porosity-elasticity coefficient; wherein, rock density, formation water density, and static Poisson's ratio are obtained from well logging data; effective stress coefficient, tectonic stress coefficient in the direction of maximum horizontal principal stress, tectonic stress coefficient in the direction of minimum horizontal principal stress, and porosity-elasticity coefficient are obtained from field data; accurate acquisition of the above parameters is the basis for subsequent calculations and analyses, and helps to improve the accuracy and reliability of the entire method.

[0026] Preferably, this invention provides specific calculation formulas for the minimum principal stress and the increase in minimum principal stress in fracturing reservoirs, making the calculation process more standardized and regulated; through the calculation formulas, the increase in minimum principal stress caused by the porosity elastic effect can be accurately calculated, ensuring accuracy.

[0027] Preferably, in this invention, by performing preprocessing operations such as data cleaning and normalization on the geomechanical parameters, outliers and noise interference in the data can be eliminated, thereby improving data quality and the accuracy of subsequent analysis.

[0028] Preferably, in this invention, comparative analysis can be used to evaluate the changes in closure pressure and its influencing factors during fracturing, providing guidance and reference for subsequent fracturing operations; this step helps to optimize fracturing operation plans and improve operational efficiency and safety. Attached Figure Description

[0029] Figure 1 A schematic color illustration of geomechanical parameters obtained from well logging data, provided for an embodiment of the present invention; Figure 2 A schematic color illustration of the minimum principal stress calculated using a dynamic correction method, provided for an embodiment of the present invention; Figure 3 A schematic color diagram illustrating the minimum principal stress increase caused by the porosity effect calculated using a dynamic correction method, provided for an embodiment of the present invention. Figure 4 A schematic diagram illustrating the effective closure pressure of a crack calculated using a dynamic correction method, provided for an embodiment of the present invention; Figure 5 A flowchart illustrating a dynamic correction method for closure pressure during fracturing, provided as an embodiment of the present invention; Figure 6 This is a schematic diagram of a dynamic correction system for closure pressure during fracturing, provided in an embodiment of the present invention. Detailed Implementation

[0030] This invention provides a method for dynamically correcting the closure pressure during fracturing, such as... Figure 5 As shown, it includes the following steps: S1: Obtain the geomechanical parameters of the target well; specifically, the geomechanical parameters include rock density, formation water density, Young's modulus, Poisson's ratio, effective stress coefficient, tectonic stress coefficient in the direction of maximum horizontal principal stress, tectonic stress coefficient in the direction of minimum horizontal principal stress, and porosity-elasticity coefficient; among which, rock density, formation water density, and static Poisson's ratio are obtained through well logging data; effective stress coefficient, tectonic stress coefficient in the direction of maximum horizontal principal stress, tectonic stress coefficient in the direction of minimum horizontal principal stress, and porosity-elasticity coefficient are obtained through field data.

[0031] Here, after obtaining the geomechanical parameters of the target well, the geomechanical parameters are preprocessed; the data preprocessing methods include: data cleaning and data normalization.

[0032] S2: The minimum principal stress and the increase in minimum principal stress of the fracturing reservoir are calculated based on geomechanical parameters. The increase in minimum principal stress is generated by the pore elastic effect during fracturing. Specifically: The minimum principal stress of the fracturing reservoir was calculated based on geomechanical parameters. s h The specific formula is as follows:

[0033] In the formula: K H The tectonic stress coefficient in the direction of the maximum horizontal principal stress is dimensionless. K h The tectonic stress coefficient in the direction of the minimum horizontal principal stress is dimensionless. E Young's modulus, GPa; y wo Poisson's ratio is dimensionless. α The effective stress coefficient is dimensionless. s v The vertical stress is measured in MPa. P p Formation pressure, MPa;

[0034] In the formula: s v The vertical stress is measured in MPa. r Density of rock, g / cm³ 3 ; h Let m be the depth. H ρ is the reservoir depth, m; g is the gravitational acceleration, m / s². 2 ;

[0035] In the formula:P p Formation pressure, MPa; r 水 Density of formation water, g / cm³ 3 ; h Depth, m; g, acceleration due to gravity, m / s² 2 .

[0036] The minimum principal stress increase Δ was calculated based on geomechanical parameters. s The specific formula is as follows:

[0037] In the formula: P wf The bottom hole flowing pressure is in MPa. P 0 represents the original formation pressure, in MPa; β The porosity coefficient is dimensionless. u Poisson's ratio is dimensionless.

[0038] In the formula: P wf The bottom hole flowing pressure is in MPa. P t The wellhead oil pressure, in MPa, is obtained from construction data. P hi The pressure is the liquid column pressure, in MPa. P fl The theoretical value of wellbore fracturing fluid friction at maximum displacement, in MPa;

[0039] In the formula: P hi The pressure is the liquid column pressure, in MPa. r i The density of the liquid is kg / m³. 3 ; h i The height of the liquid column is m; g is the acceleration due to gravity, m / s². 2 ; i i The wellbore inclination angle corresponding to the liquid, in rad; P fl =σP f0 In the formula: P fl The theoretical value of wellbore fracturing fluid friction at maximum displacement, in MPa; s The drag reduction ratio is dimensionless. Pf0 The theoretical value of wellbore friction under maximum discharge rate, in MPa;

[0040] In the formula: s The drag reduction ratio is dimensionless. d The diameter of the wellbore is in mm; Q max The maximum displacement during construction, m 3 / min; G Thickener concentration, kg / m³ 3 ;

[0041] In the formula: P f0 The theoretical value of wellbore friction under maximum discharge rate, in MPa; d The diameter of the wellbore is in mm; Q max The maximum displacement during construction, m 3 / min.

[0042] S3: The effective closure pressure of the fracture is obtained based on the minimum principal stress and the increase of the minimum principal stress in the fracturing reservoir, so as to achieve dynamic correction of the closure pressure.

[0043] Specifically, the effective closure pressure of the fracture is obtained based on the minimum principal stress and the increase in minimum principal stress of the fracturing reservoir. P s The specific formula is as follows: P s = s h + Δ s In the formula: s h For the minimum principal stress, MPa ;Δ s This is the increase in minimum principal stress. MPa .

[0044] This correction method also includes: comparing and analyzing the obtained effective closure pressure of the fracture with the initial closure pressure to obtain the comparison analysis results, thereby evaluating the changes in closure pressure and its influencing factors during the fracturing process based on the comparison results, and providing guidance and reference for subsequent fracturing operations.

[0045] like Figure 6As shown, the present invention also provides a dynamic correction system for closure pressure during fracturing, comprising: a data acquisition module for acquiring geomechanical parameters of the target well; a stress calculation module for calculating the minimum principal stress and the increase in minimum principal stress of the fracturing reservoir based on the geomechanical parameters, wherein the increase in minimum principal stress is generated by the pore elastic effect during fracturing; and a pressure correction module for obtaining the effective closure pressure of the fracture based on the minimum principal stress and the increase in minimum principal stress of the fracturing reservoir, so as to achieve dynamic correction of the closure pressure.

[0046] The present invention also provides an apparatus comprising: a memory for storing a computer program; and a processor for executing the computer program to implement the steps of the dynamic correction method for closure pressure during fracturing.

[0047] When the processor executes the computer program, it implements the steps of dynamically correcting the closure pressure during the fracturing process, such as: obtaining the geomechanical parameters of the target well; calculating the minimum principal stress and the increase in minimum principal stress of the fracturing reservoir based on the geomechanical parameters, wherein the increase in minimum principal stress is generated by the pore elastic effect during fracturing; and obtaining the effective closure pressure of the fracture based on the minimum principal stress and the increase in minimum principal stress of the fracturing reservoir, so as to achieve dynamic correction of the closure pressure.

[0048] Alternatively, when the processor executes the computer program, it implements the functions of each module in the above system, such as: a data acquisition module for acquiring the geomechanical parameters of the target well; a stress calculation module for calculating the minimum principal stress and the increase in minimum principal stress of the fracturing reservoir based on the geomechanical parameters, wherein the increase in minimum principal stress is generated by the pore elastic effect during fracturing; and a pressure correction module for obtaining the effective closure pressure of the fracture based on the minimum principal stress and the increase in minimum principal stress of the fracturing reservoir, so as to achieve dynamic correction of the closure pressure.

[0049] Exemplarily, the computer program can be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules / units can be a series of computer program instruction segments capable of performing preset functions, the instruction segments describing the execution process of the computer program in the dynamic correction device for closure pressure during fracturing. For example, the computer program can be divided into a data acquisition module, a stress calculation module, and a pressure correction module; the specific functions of each module are as follows: the data acquisition module is used to acquire the geomechanical parameters of the target well; the stress calculation module is used to calculate the minimum principal stress and the minimum principal stress increment of the fracturing reservoir based on the geomechanical parameters, wherein the minimum principal stress increment is generated by the pore elastic effect during fracturing; the pressure correction module is used to obtain the effective closure pressure of the fracture based on the minimum principal stress and the minimum principal stress increment of the fracturing reservoir, so as to achieve dynamic correction of the closure pressure.

[0050] The dynamic correction device for closing pressure during fracturing can be a computing device such as a desktop computer, laptop, handheld computer, or cloud server. This device may include, but is not limited to, a processor and memory. Those skilled in the art will understand that the above are examples of dynamic correction devices for closing pressure during fracturing and do not constitute a limitation on such devices. The device may include more components than described above, or combine certain components, or use different components. For example, the dynamic correction device for closing pressure during fracturing may also include input / output devices, network access devices, buses, etc.

[0051] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor, or any conventional processor. The processor is the control center for the dynamic correction of the closing pressure during the fracturing process, connecting various parts of the dynamic correction equipment for the closing pressure throughout the fracturing process via various interfaces and lines.

[0052] The memory can be used to store the computer program and / or modules. The processor realizes various functions of the dynamic correction device for closing pressure during fracturing by running or executing the computer program and / or modules stored in the memory and calling the data stored in the memory.

[0053] The memory may primarily include a program storage area and a data storage area. The program storage area may store the operating system and at least one application program required for a function (such as sound playback, image playback, etc.). The data storage area may store data created based on the use of the mobile phone (such as audio data, phonebook, etc.). Furthermore, the memory may include high-speed random access memory and non-volatile memory, such as hard disks, RAM, plug-in hard disks, smart media cards (SMC), secure digital cards (SD cards), flash cards, at least one disk storage device, flash memory device, or other volatile solid-state storage devices.

[0054] The present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the dynamic correction method for closure pressure during fracturing.

[0055] If the module / unit of the dynamic correction system for closure pressure during fracturing is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium.

[0056] Based on this understanding, the present invention can implement all or part of the process of the dynamic correction method for closure pressure during fracturing, which can also be accomplished by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the dynamic correction method for closure pressure during fracturing. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or a preset intermediate form, etc.

[0057] The computer-readable storage medium may include: any entity or device capable of carrying the computer program code, recording media, USB flash drive, portable hard drive, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal, and software distribution medium, etc.

[0058] It should be noted that the content contained in the computer-readable storage medium may be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable storage medium does not include electrical carrier signals and telecommunication signals.

[0059] The present invention will be further described below with reference to embodiments and accompanying drawings: Example 1 As described in the background section, current methods for calculating minimum principal stress mainly include pore elastic horizontal strain models, triaxial strain models, Mohr-Coulomb stress models, uniaxial strain empirical relations, Huang's empirical relations, combined spring empirical relations, differential empirical relations, and Ge's geostress empirical relations. All of these methods are derived from geomechanical parameters. However, the minimum principal stress predicted using these methods based on geomechanical parameters still differs from the fracture closure pressure calculated through analysis, testing, and fracturing operations. This is primarily because these prediction methods do not consider the influence of pore elasticity. During fracturing, fracturing fluid leaks into the formation, causing an increase in pore pressure near the fracture and resulting in formation swelling, thus increasing the minimum principal stress in that area. During well shut-in and flowback, the fracture remains open due to the proppant effect; therefore, this stress increase persists. Therefore, there is an urgent need for a closure pressure prediction method that considers the pore elastic effect to achieve dynamic correction of the closure pressure during fracturing.

[0060] To achieve the above objectives, this embodiment provides a dynamic correction method for the closure pressure during fracturing, which can solve the problem of inaccurate prediction of the closure pressure before fracturing. This allows for dynamic adjustment of fracturing parameters during the fracturing process, improving the fracturing effect and increasing post-fracturing production.

[0061] This embodiment provides a method for dynamically correcting the closure pressure during fracturing, specifically including the following steps: S1: Obtain the following geomechanical parameters from the target well: rock density, formation water density, Young's modulus, Poisson's ratio, effective stress coefficient, tectonic stress coefficient in the direction of maximum horizontal principal stress, tectonic stress coefficient in the direction of minimum horizontal principal stress, and porosity-elasticity coefficient. Specifically, the rock density, formation water density, and static Poisson's ratio are obtained from well logging data; the effective stress coefficient, tectonic stress coefficient in the direction of maximum horizontal principal stress, tectonic stress coefficient in the direction of minimum horizontal principal stress, and porosity-elasticity coefficient are obtained from field data.

[0062] To improve data quality and the accuracy of subsequent analysis, preprocessing operations such as data cleaning and normalization of geomechanical parameters are performed to eliminate outliers and noise interference in the data. The preprocessed geomechanical parameters are then output for application in S2.

[0063] S2: Calculation of minimum principal stress in fracturing reservoirs based on preprocessed geomechanical parameters. s h The specific formula is as follows:

[0064] In the formula: K H The tectonic stress coefficient in the direction of the maximum horizontal principal stress is dimensionless. K h The tectonic stress coefficient in the direction of the minimum horizontal principal stress is dimensionless. E Young's modulus, GPa; y wo Poisson's ratio is dimensionless. α The effective stress coefficient is dimensionless. s v The vertical stress is measured in MPa. P p Formation pressure, MPa;

[0065] In the formula: s v The vertical stress is measured in MPa. r Density of rock, g / cm³ 3 ; h Let m be the depth. H ρ is the reservoir depth, m; g is the gravitational acceleration, m / s². 2 ;

[0066] In the formula: P p Formation pressure, MPa; r 水 Density of formation water, g / cm³ 3 ; h Depth, m; g, acceleration due to gravity, m / s² 2 .

[0067] S3: Calculate the minimum principal stress increase Δ caused by the pore elastic effect during fracturing based on the preprocessed geomechanical parameters. s The specific formula is as follows:

[0068] In the formula: P wf The bottom hole flowing pressure is in MPa. P 0 represents the original formation pressure, in MPa;β The porosity coefficient is dimensionless. u Poisson's ratio is dimensionless.

[0069] In the formula: P wf The bottom hole flowing pressure is in MPa. P t The wellhead oil pressure, in MPa, is obtained from construction data. P hi The pressure is the liquid column pressure, in MPa. P fl The theoretical value of wellbore fracturing fluid friction at maximum displacement, in MPa;

[0070] In the formula: P hi The pressure is the liquid column pressure, in MPa. r i The density of the liquid is kg / m³. 3 ; h i The height of the liquid column is m; g is the acceleration due to gravity, m / s². 2 ; i i The wellbore inclination angle corresponding to the liquid, in rad; P fl =σP f0 In the formula: P fl The theoretical value of wellbore fracturing fluid friction at maximum displacement, in MPa; s The drag reduction ratio is dimensionless. P f0 The theoretical value of wellbore friction under maximum discharge rate, in MPa;

[0071] In the formula: s The drag reduction ratio is dimensionless. d The diameter of the wellbore is in mm; Q max The maximum displacement during construction, m 3 / min; G Thickener concentration, kg / m³ 3 ;

[0072] In the formula: P f0 The theoretical value of wellbore friction under maximum discharge rate, in MPa;d The diameter of the wellbore is in mm; Q max The maximum displacement during construction, m 3 / min.

[0073] Of course, the actual order of S2 and S3 can also be changed or calculated simultaneously.

[0074] S4: Calculate the effective closure pressure of the fracture based on the minimum principal stress and the increase in minimum principal stress of the fracturing reservoir. P s This is to achieve dynamic correction of the closing pressure, and the specific formula is as follows: P s = s h + Δ s In the formula: s h For the minimum principal stress, MPa ;Δ s This is the increase in minimum principal stress. MPa .

[0075] S5: Compare and analyze the effective closure pressure of the fracture with the initial closure pressure to obtain the comparison analysis results. Through comparison and analysis, the changes in closure pressure and its influencing factors during fracturing can be evaluated, providing guidance and reference for subsequent fracturing operations. This step helps to optimize fracturing operation plans and improve operational efficiency and safety.

[0076] Example 2 In this embodiment, the dynamic correction method for closure pressure during fracturing mentioned in Example 1 is applied to the closure pressure prediction stage during the fracturing process of a specific target well. The target well belongs to a fractured tight sandstone reservoir. In order to improve the production of the single well, it is necessary to fracture the reservoir. In order to reasonably set the construction parameters and improve the success rate of fracturing, it is necessary to dynamically correct the closure pressure during the fracturing process. The specific implementation steps are as follows: S1. Obtain the geomechanical parameters of the target well.

[0077] like Figure 1 As shown, the reservoir rock density, formation water density, Young's modulus, and Poisson's ratio were obtained from well logging data; the effective stress coefficient obtained from field data was 1.00, the tectonic stress coefficient in the direction of maximum horizontal principal stress was 0.73, the tectonic stress coefficient in the direction of minimum horizontal principal stress was 0.65, and the porosity coefficient was 0.25.

[0078] S2. Calculate the minimum principal stress of the fracturing reservoir based on geomechanical parameters.

[0079] like Figure 2 As shown, the minimum principal stress of the fracturing reservoir is calculated based on geomechanical parameters.

[0080] S3, such as Figure 3 As shown, the minimum principal stress increase caused by the pore elastic effect during fracturing is calculated.

[0081] The density of the fracturing fluid obtained from the construction data is 1.35 g / cm³. 3 The thickener concentration is 0.65 g / cm³. 3 The fracturing fluid injection volume is 1000m³. 3 The maximum injection displacement of fracturing fluid is 8m³. 3 / min. The calculated minimum increase in principal stress caused by the pore elastic effect during construction.

[0082] S4. For example Figure 4 As shown, the effective closure pressure of the fracture is obtained by adding the minimum principal stress calculated based on geomechanical parameters to the increase in minimum principal stress caused by considering the pore elastic effect.

[0083] It is evident that the calculation results of this method are closer to the actual situation, and it can achieve dynamic correction of the closing pressure during fracturing, thereby optimizing construction parameters and improving construction results; it can provide effective reference and guidance for fracturing construction of other wells.

[0084] In summary, this invention provides a dynamic correction method for closure pressure during fracturing, which has the following advantages compared to existing closure pressure prediction methods: This invention provides a dynamic correction method for closure pressure during fracturing. The method utilizes geomechanical parameters encompassing rock density, formation water density, Young's modulus, Poisson's ratio, effective stress coefficient, tectonic stress coefficient, and porosity-elasticity coefficient. These parameters are obtained not only based on well logging data but also incorporating field data, resulting in a more comprehensive and specific parameter acquisition. This comprehensive parameter acquisition approach helps improve the accuracy and reliability of subsequent calculations and analyses.

[0085] By acquiring the geomechanical parameters of the target well and calculating the minimum principal stress of the fracturing reservoir and the increase in minimum principal stress due to the porosity elastic effect based on these parameters, the effective closure pressure of the fracture can be obtained. This method considers the actual geological conditions and dynamic changes during fracturing operations, thus more accurately reflecting the closure pressure during fracturing and improving the accuracy of dynamic correction.

[0086] The above embodiments are merely one of the implementation methods for achieving the technical solution of the present invention. The scope of protection claimed by the present invention is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention.

Claims

1. A method for dynamic correction of closure pressure during fracturing, characterized in that, include: Obtain the geomechanical parameters of the target well; The minimum principal stress and the increase in minimum principal stress of the fracturing reservoir were calculated based on geomechanical parameters, wherein the increase in minimum principal stress was generated by the pore elastic effect during the fracturing operation. The effective closure pressure of the fracture is obtained based on the minimum principal stress and the increase of the minimum principal stress in the fracturing reservoir, so as to achieve dynamic correction of the closure pressure.

2. The method for dynamic correction of closure pressure during fracturing according to claim 1, characterized in that, The geomechanical parameters include rock density, formation water density, Young's modulus, Poisson's ratio, effective stress coefficient, tectonic stress coefficient in the direction of maximum horizontal principal stress, tectonic stress coefficient in the direction of minimum horizontal principal stress, and porosity coefficient.

3. The method for dynamic correction of closure pressure during fracturing according to claim 1, characterized in that, The minimum principal stress of the fracturing reservoir was calculated based on geomechanical parameters. σ h It is calculated based on the tectonic stress coefficient in the direction of maximum horizontal principal stress and the tectonic stress coefficient in the direction of minimum horizontal principal stress; The specific formula is as follows: In the formula: K H The tectonic stress coefficient in the direction of the maximum horizontal principal stress is dimensionless. K h The tectonic stress coefficient in the direction of the minimum horizontal principal stress is dimensionless. E Young's modulus, GPa; υ is Poisson's ratio is dimensionless. α The effective stress coefficient is dimensionless. σ v The vertical stress is measured in MPa. P p Formation pressure, MPa; In the formula: σ v The vertical stress is measured in MPa. ρ Density of rock, g / cm³ 3 ; h Let m be the depth. H ρ is the reservoir depth, m; g is the gravitational acceleration, m / s². 2 ; In the formula: P p Formation pressure, MPa; ρ 水 Density of formation water, g / cm³ 3 ; h Depth, m; g, acceleration due to gravity, m / s² 2 .

4. The method for dynamic correction of closure pressure during fracturing according to claim 1, characterized in that, The minimum principal stress increase Δ was calculated based on geomechanical parameters. σ It was calculated based on the bottom hole flowing pressure, the original formation pressure, and the porosity coefficient. The specific formula is as follows: In the formula: P wf The bottom hole flowing pressure is in MPa. P 0 represents the original formation pressure, in MPa; β The porosity coefficient is dimensionless. υ Poisson's ratio is dimensionless. In the formula: P wf The bottom hole flowing pressure is in MPa. P t The wellhead oil pressure, in MPa, is obtained from construction data. P hi The pressure is the liquid column pressure, in MPa. P fl The theoretical value of wellbore fracturing fluid friction at maximum displacement, in MPa; In the formula: P hi The pressure is the liquid column pressure, in MPa. ρ i The density of the liquid is kg / m³. 3 ; h i The height of the liquid column is m; g is the acceleration due to gravity, m / s². 2 ; θ i The wellbore inclination angle corresponding to the liquid, in rad; P fl =σP f0 In the formula: P fl The theoretical value of wellbore fracturing fluid friction at maximum displacement, in MPa; σ The drag reduction ratio is dimensionless. P f0 The theoretical value of the wellbore friction under maximum discharge rate, in MPa; In the formula: σ The drag reduction ratio is dimensionless. d The diameter of the wellbore is in mm; Q max The maximum displacement during construction, m 3 / min; G Thickener concentration, kg / m³ 3 ; In the formula: P f0 The theoretical value of wellbore friction under maximum discharge rate, in MPa; d The diameter of the wellbore is in mm; Q max The maximum displacement during construction, m 3 / min.

5. The method for dynamic correction of closure pressure during fracturing according to claim 1, characterized in that, The effective closing pressure of the crack P s Calculated based on the minimum principal stress and the increase in minimum principal stress during fracturing; The specific formula is as follows: P s = σ h + D σ In the formula: σ h For the minimum principal stress, MPa ;Δ σ This is the increase in minimum principal stress. MPa .

6. The method for dynamic correction of closure pressure during fracturing according to claim 1, characterized in that, Also includes: After obtaining the geomechanical parameters of the target well, the geomechanical parameters are preprocessed. Data preprocessing methods include: data cleaning and data normalization.

7. A dynamic correction system for closure pressure during fracturing, used to implement the steps of the dynamic correction method for closure pressure during fracturing as described in any one of claims 1-6, characterized in that, include: The data acquisition module is used to obtain the geomechanical parameters of the target well; The stress calculation module is used to calculate the minimum principal stress and the minimum principal stress increase value of the fracturing reservoir based on geomechanical parameters, wherein the minimum principal stress increase value is generated by the pore elastic effect during the fracturing operation. The pressure correction module is used to obtain the effective closure pressure of the fracture based on the minimum principal stress and the minimum principal stress increase value of the fracturing reservoir, so as to achieve dynamic correction of the closure pressure.

8. A device, characterized in that, include: Memory, used to store computer programs; A processor, configured to execute the computer program to implement the steps of the dynamic correction method for closure pressure during fracturing as described in any one of claims 1-6.

9. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it is used to implement the steps of the dynamic correction method for closure pressure during fracturing as described in any one of claims 1-6.

10. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instruction is executed by the processor, it implements the steps of the dynamic correction method for closure pressure during fracturing as described in claims 1-6.

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