Method for calculating distributed pressure of fractured horizontal well based on same-well optical fiber strain monitoring simulation

Abstract

The invention discloses a method for calculating distributed pressure of a fractured horizontal well based on same-well optical fiber strain monitoring simulation, and relates to the technical field of oil and gas field exploitation, and the method comprises the following steps: establishing a physical model of fracture fluid production and optical fiber strain monitoring; establishing a reservoir stratum geomechanical calculation model and a bottom hole pressure calculation model in the horizontal well production process; on the basis of the physical model of fracture fluid production and optical fiber strain monitoring, according to the reservoir geomechanical calculation model and the bottom hole pressure calculation model, the same-well optical fiber strain data and the bottom hole pressure under different production conditions of the horizontal well are calculated respectively; according to the same-well optical fiber strain data of the horizontal well under different production conditions and the bottom hole pressure, fitting to obtain a first relational expression between bottom hole pressure change and optical fiber strain; optical fiber strain data actually captured on site are substituted into the first relational expression obtained through fitting, and pressure distribution along the optical fiber is obtained through calculation.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field exploitation, and in particular to a method for calculating distributed pressure of a fractured horizontal well based on same-well optical fiber strain monitoring simulation. Background Art

[0002] Hydraulic fracturing is a key technology in the process of oil and gas extraction. It creates artificial cracks by injecting high-pressure fluids and proppants into the formation to improve the permeability of the oil and gas layer, expand the oil and gas seepage channel, and thus increase production. For fracturing wells, obtaining downhole data through dynamic monitoring of oil wells can better understand the reservoir development status and evaluate the fracturing effect. With the development of fiber optic sensing technology, distributed fiber optic strain monitoring technology has been gradually applied to the development of oil and gas fields due to its advantages such as higher resolution, sensitivity and longer monitoring time.

[0003] Distributed optical fiber strain sensing uses the optical fiber photoelastic sensitivity to monitor the changes in the propagation speed of light in the optical fiber, thereby obtaining reservoir physical parameters and fluid dynamic change information. When the optical fiber is subjected to stress, the propagation speed of electromagnetic waves in the optical fiber will change. By analyzing the changes in the scattered light signal, the strain distribution along the optical fiber can be obtained, thereby achieving continuous monitoring of the entire length of the optical fiber.

[0004] At present, distributed optical fiber strain monitoring mainly uses the optical fiber strain characteristics of adjacent wells to analyze the initiation, expansion, compression and penetration of cracks during fracturing. The same-well optical fiber strain monitoring technology based on Rayleigh scattering combines the advantages of Rayleigh scattering principle and optical fiber sensors, and can achieve high-precision monitoring of physical quantities such as strain and temperature within the entire length of the optical fiber. As a new monitoring method, although it has been successfully applied in fracturing sites in some areas and has made certain progress in the optical fiber strain response signal, it is still in its infancy. There are still many deficiencies in related theoretical research, especially in complex geological environments. The interaction of multiple factors such as strain, temperature, pore pressure, and fracture distribution in the reservoir leads to nonlinear changes in the optical fiber response signal. The existing coupling model mainly targets simple linear strain-stress relationships and is difficult to cope with the multi-physical field coupling problem under complex reservoir conditions.

[0005] The amount of data generated by optical fiber monitoring is large, which requires efficient processing and analysis methods. However, the current technology still has great difficulties in noise reduction processing and data interpretation. Therefore, finding the relationship between the optical fiber response signal and the bottom hole pressure and establishing a horizontal well bottom hole pressure calculation method based on the optical fiber strain data of the same well are beneficial to explore the influence of different production states of oil wells on the stress of the bottom hole rock and the flow of formation fluids, expand the research content in related fields, and are of great significance for analyzing the changes in downhole pressure and rock stress field through strain characteristic signals, and evaluating the oil production capacity and fracturing transformation effect of the reservoir.

[0006] The above contents are only used to assist in understanding the technical solution of the present invention and do not constitute an admission that the above contents are prior art. Summary of the invention

[0007] The main purpose of the present invention is to provide a method for calculating the distributed pressure of a fractured horizontal well based on the simulation of optical fiber strain monitoring in the same well, aiming to solve or partially solve the above problems.

[0008] To achieve the above object, the present invention provides a method for calculating the distributed pressure of a fractured horizontal well based on the simulation of optical fiber strain monitoring in the same well, comprising: Establishing a physical model of fracture fluid production and optical fiber strain monitoring, wherein the physical model of fracture fluid production and optical fiber strain monitoring includes reservoir geological parameters and fracturing construction parameters; Establish reservoir geomechanics calculation model and bottom hole pressure calculation model during horizontal well production; Based on the physical model of fracture fluid production and optical fiber strain monitoring, according to the reservoir geomechanics calculation model and the bottom hole pressure calculation model, respectively calculate the optical fiber strain data of the same well and the bottom hole pressure under different production conditions of the horizontal well; According to the optical fiber strain data of the horizontal well under different production conditions and the bottom hole pressure, the first relationship between the bottom hole pressure change and the optical fiber strain is obtained by fitting; The optical fiber strain data actually captured on site is substituted into the first fitted equation to calculate the pressure distribution along the optical fiber.

[0009] Preferably, in the method for calculating the distributed pressure of a fractured horizontal well based on the same-well optical fiber strain monitoring simulation, in the step of establishing a reservoir geomechanics calculation model and a bottom hole pressure calculation model during the horizontal well production process, the reservoir geomechanics calculation model includes: Based on the principle of momentum conservation and Biot's poroelasticity theory, the equilibrium equation of rock skeleton deformation is: ; (1) When the rock undergoes a small deformation, the equation for the relationship between reservoir rock stress and strain is: ; (2) in, σ is the stress tensor, in MPa; ρ m is the rock skeleton density, in kg / m 3 ; g is the acceleration due to gravity, in m / s 2 ; σ0 is the stress tensor at the initial moment, in MPa; C is the elastic stiffness tensor; ε is the strain tensor; α is the Boit coefficient, with the unit being 1; I is the unit tensor; Φ m is the reservoir porosity; p is the pore pressure; p0 is the initial pore pressure.

[0010] Preferably, in the method for calculating the distributed pressure of a fractured horizontal well based on the same-well optical fiber strain monitoring simulation, in the step of establishing a reservoir geomechanics calculation model and a bottom hole pressure calculation model during the horizontal well production process, the bottom hole pressure calculation model includes: The flow of fluid in porous media satisfies the mass conservation equation: ; Assuming that the flow of fluid in porous media is linear and satisfies Darcy's law, the fluid flow velocity is: ; The fluid seepage in the entire reservoir is divided into two parts: flow in the rock matrix and flow in the fractures. Combining the mass conservation law with Darcy's law, the seepage equations for the two parts are obtained. Among them, the governing equation of two-dimensional matrix flow is: ; The governing equation for one-dimensional fracture flow is: ; Where n is the porosity, with the unit being 1; ρ f is the fluid density in kg / m 3 ; V f is the average velocity of the fluid, in m / s; k is the formation permeability, in mD; μ is the fluid viscosity, in mPa·s; p is the pore pressure, in MPa; K m is the reservoir permeability, in m 2 ; μ is the fluid viscosity, in Pa·s; p m is the reservoir pressure, in Pa; Φ m is the reservoir porosity, with a unit of 1; C t is the comprehensive compression coefficient, in Pa -1 ; t is time, in seconds; K f is the reservoir permeability, in m 2 ; p f is the crack pressure, in Pa; l is the one-dimensional local coordinate of the crack; Φ f is the fracture porosity.

[0011] Preferably, in the method for calculating the distributed pressure of a fractured horizontal well based on the simulation of optical fiber strain monitoring in the same well, the physical model based on the fracture fluid production and optical fiber strain monitoring, according to the reservoir geomechanics calculation model and the bottom hole pressure calculation model, respectively calculates the optical fiber strain data in the same well under different production conditions of the horizontal well and the bottom hole pressure, including: According to the reservoir geomechanics calculation model and the physical model based on the fracture fluid production and optical fiber strain monitoring, the finite element method is used to calculate the optical fiber strain data of the horizontal well under different production conditions; According to the bottom hole pressure calculation model and the physical model based on the fracture fluid production and optical fiber strain monitoring, the bottom hole pressure under different production conditions of the horizontal well is calculated using the finite element method.

[0012] Preferably, in the method for calculating the distributed pressure of a fractured horizontal well based on the same-well optical fiber strain monitoring simulation, the step of fitting the first relationship between the bottom hole pressure change and the optical fiber strain according to the same-well optical fiber strain data under different production conditions of the horizontal well and the bottom hole pressure comprises: According to the optical fiber strain data of the horizontal well under different production conditions and the bottom hole pressure, the curve of bottom hole pressure change and optical fiber strain is fitted; The obtained curve is plotted using data analysis software, and the data is fitted using the least squares method to obtain the first relationship.

[0013] Preferably, in the method for calculating the distributed pressure of a fractured horizontal well based on the simulation of optical fiber strain monitoring in the same well, before the step of bringing the optical fiber strain data actually captured on site into the first relationship obtained by fitting to calculate the pressure distribution along the optical fiber, the method further includes: The optical fiber strain data actually captured on site is processed through filtering and noise reduction.

[0014] Preferably, in the method for calculating the distributed pressure of a fractured horizontal well based on the same-well optical fiber strain monitoring simulation, the first relationship is a binary linear equation.

[0015] Preferably, in the method for calculating the distributed pressure of a fractured horizontal well based on the same-well optical fiber strain monitoring simulation, the reservoir geological parameters include ground stress parameters, rock elastic modulus, Poisson's ratio, and permeability; The fracturing construction parameters include the spacing and number of clusters of artificial fractures formed by fracturing.

[0016] The present invention has at least the following beneficial effects: The method for calculating the distributed pressure of a fractured horizontal well based on the simulation of optical fiber strain monitoring in the same well provided by the present invention establishes a physical model of fracture fluid production and optical fiber strain monitoring, wherein the physical model of fracture fluid production and optical fiber strain monitoring includes reservoir geological parameters and fracturing construction parameters; establishes a reservoir geomechanics calculation model and a bottom hole pressure calculation model during the production of a horizontal well; based on the physical model of fracture fluid production and optical fiber strain monitoring, according to the reservoir geomechanics calculation model and the bottom hole pressure calculation model, respectively calculates the optical fiber strain data in the same well and the bottom hole pressure under different production conditions of the horizontal well; according to different production conditions of the horizontal well, the calculation model of the reservoir geomechanics calculation model and the bottom hole pressure calculation model are used to calculate the distributed pressure of the fractured ... The optical fiber strain data of the same well under the same conditions and the bottom hole pressure are used to fit the first relationship between the bottom hole pressure change and the optical fiber strain; the optical fiber strain data actually captured on site is brought into the first fitted relationship to calculate the pressure distribution along the optical fiber. In this way, a method for calculating the bottom hole pressure of a horizontal well based on the optical fiber strain data of the same well can be established, which is conducive to exploring the influence of different production states of oil wells on the stress of the bottom rock of the oil well and the flow of formation fluids, expanding the research content in related fields, and is of great significance for analyzing the changes in downhole pressure and rock stress field through strain characteristic signals, and evaluating the oil production capacity and fracturing transformation effect of the reservoir; Furthermore, according to the geological and construction parameters of the target well, the optical fiber strain response signal is simulated to clarify the influence of different downhole conditions on the optical fiber strain response and bottom hole pressure, and the correlation between optical fiber strain and bottom hole pressure is clarified. The bottom hole pressure along the axis of the wellbore at a certain moment is calculated based on the optical fiber strain response data obtained and processed on site, and the distributed bottom hole pressure is used to perform well test analysis of the subsequent production status of the fracturing well under complex formation conditions, providing decision support for the formulation of reasonable operation plans for subsequent exploitation, improving oilfield exploitation efficiency, and reducing operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of a method for calculating distributed pressure of a fractured horizontal well based on the same-well optical fiber strain monitoring simulation provided by the present invention; Figure 2 This is an example diagram of the relationship between the optical fiber strain and the bottom hole pressure at the perforation position; Figure 3 It is an example diagram of the distributed pressure distribution along the wellbore axis at different times during the well opening stage; Figure 4The diagram is an example of the distributed pressure distribution along the wellbore axis at different times during the shut-in phase.

[0018] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0019] In the embodiments of the present invention, the term "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent three situations: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0020] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0021] In the embodiments of the present invention, the term "plurality" refers to two or more than two, and other quantifiers are similar.

[0022] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. However, it can be understood by those skilled in the art that in the embodiments of the present invention, many technical details are proposed in order to enable the reader to better understand the present invention. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed in the present invention can also be implemented. The division of the following embodiments is for the convenience of description and should not constitute any limitation on the specific implementation of the present invention. The various embodiments can be combined and referenced with each other under the premise of no contradiction.

[0023] The present invention provides a method for calculating the distributed pressure of a fractured horizontal well based on the simulation of optical fiber strain monitoring in the same well, such as Figure 1 shown.

[0024] In step S100, a physical model of crack fluid production and optical fiber strain monitoring is established.

[0025] The physical model of fracture fluid production and optical fiber strain monitoring includes information such as reservoir geological parameters and fracturing construction parameters. The reservoir geological parameters include ground stress parameters, rock elastic modulus, Poisson's ratio, and permeability. The fracturing construction parameter information includes the spacing and number of artificial fracture clusters formed by fracturing.

[0026] The physical model of fracture fluid production and optical fiber strain monitoring can be established based on reservoir geological parameters and fracturing operation parameters. Take an oil well as an example, where some reservoir geological parameters and fracturing operation parameter information are shown in Table 1.

[0027] Table 1 Some parameters of an oil well It should be noted that the reservoir and the wellbore are connected through perforations, the fluid in the fracture flows into the wellbore through the perforated holes, and the optical fiber is arranged in the casing parallel to the axis of the wellbore.

[0028] In step S200, a reservoir geomechanics calculation model and a bottom hole pressure calculation model are established during the horizontal well production process.

[0029] It should be noted that the reservoir geomechanics calculation model and the bottom hole pressure calculation model are divided into two parts according to the region: the reservoir matrix model and the fracture model. Each part includes a fluid flow model and a rock deformation model. The fluid flow model is mainly described by the mass conservation equation and Darcy's law, and the rock deformation model is mainly described by the continuum mechanics theory, the mass conservation equation, and the momentum conservation equation.

[0030] Wherein, the bottom hole pressure calculation model includes: The flow of fluid in porous media satisfies the mass conservation equation: ; Assuming that the flow of fluid in porous media is linear and satisfies Darcy's law, the fluid flow velocity is: ; The fluid seepage in the entire reservoir is divided into two parts: flow in the rock matrix and flow in the fractures. Combining mass conservation with Darcy's law, the seepage equations of the two parts are obtained, among which the two-dimensional matrix flow control equation is: ; The governing equation for one-dimensional fracture flow is: ; Where n is the porosity, with the unit being 1; ρ f is the fluid density in kg / m 3 ; V f is the average velocity of the fluid, in m / s; k is the formation permeability, in mD; μ is the fluid viscosity, in mPa·s; p is the pore pressure, in MPa; K m is the reservoir permeability, in m 2 ; μ is the fluid viscosity, in Pa·s; p m is the reservoir pressure, in Pa; Φ m is the reservoir porosity, with a unit of 1; C t is the comprehensive compression coefficient, in Pa -1 ; t is time, in seconds; K f is the reservoir permeability, in m 2 ; p f is the crack pressure, in Pa; l is the one-dimensional local coordinate of the crack; Φ f is the fracture porosity.

[0031] It should be noted that in the one-dimensional flow control equation, when the one-dimensional local coordinate l of the crack is the half length of the crack, the corresponding crack pressure p f is the bottom hole pressure.

[0032] It should be noted that, ignoring the effects of inertial force and viscous force, in porous elastic media, fluid flow causes changes in the pore pressure of the medium, which in turn affects the volume deformation of the solid skeleton; reservoir deformation affects the stress state of the rock, and stress changes cause changes in pore pressure.

[0033] Among them, in the step of establishing a reservoir geomechanics calculation model and a bottom hole pressure calculation model during horizontal well production, the reservoir geomechanics calculation model includes: Based on the principle of momentum conservation and Biot's poroelasticity theory, the equilibrium equation of rock skeleton deformation is: ; (1) When the rock undergoes a small deformation, the equation for the relationship between reservoir rock stress and strain is: ; (2) in, σ is the stress tensor, in MPa; ρ m is the rock skeleton density, in kg / m 3 ; g is the acceleration due to gravity, in m / s 2 ; σ0 is the stress tensor at the initial moment, in MPa; C is the elastic stiffness tensor; ε is the strain tensor; α is the Boit coefficient, with the unit being 1; I is the unit tensor; Φ m is the reservoir porosity; p is the pore pressure; p0 is the initial pore pressure.

[0034] In step S300, based on the physical model of fracture fluid production and optical fiber strain monitoring, according to the reservoir geomechanics calculation model and the bottom hole pressure calculation model, the optical fiber strain data and bottom hole pressure of the horizontal well under different production conditions are calculated respectively.

[0035] More specifically, the step S300 includes: According to the reservoir geomechanics calculation model and the physical model based on the fracture fluid production and optical fiber strain monitoring, the finite element method is used to calculate the optical fiber strain data of the horizontal well under different production conditions; According to the bottom hole pressure calculation model and the physical model based on the fracture fluid production and optical fiber strain monitoring, the bottom hole pressure under different production conditions of the horizontal well is calculated using the finite element method.

[0036] It should be noted that, for the convenience of calculation, the shear and displacement between the optical fiber and the cement ring, the influence of the wellbore radius and the casing thickness are ignored, and the axial strain of the formation rock in the wellbore along the horizontal well is approximated as the optical fiber strain.

[0037] Specifically, the reservoir model is a two-dimensional model with a horizontal wellbore in the middle. Fiber optic sensors are arranged along the axis of the horizontal wellbore. There are hydraulic fractures at different positions of the wellbore. Therefore, without considering the shear and displacement between the optical fiber and the cement ring, the formation rock strain at the wellbore is the fiber optic strain, that is, the horizontal strain data of the rock along the horizontal wellbore is used as the fiber optic strain monitoring value.

[0038] In addition, the finite element method mentioned in the present invention is implemented by the finite element simulation software COMSOL. The bottom hole pressure change is caused by the well opening and well closing operations.

[0039] In step S400, a first relationship between the bottom hole pressure change and the optical fiber strain is obtained by fitting according to the optical fiber strain data of the same well under different production conditions of the horizontal well and the bottom hole pressure.

[0040] It should be noted that the optical fiber strain data and bottom hole pressure of the horizontal well under different production conditions are used.

[0041] More specifically, based on the optical fiber strain data of the same well under different production conditions of the horizontal well and the bottom hole pressure, a curve of bottom hole pressure change and optical fiber strain is fitted; the obtained curve is plotted through data analysis software, and the data is fitted using the least squares method to obtain the first relationship.

[0042] Specifically, the initial state of the wellbore and surrounding formations, including pressure and stress distribution, is first determined, and the subsequent operation of the oil well is divided into a short-term well opening production process and a long-term well closing pressure recovery process, wherein the oil well liquid production is set to a fixed value in the well opening production stage, and the oil well liquid production is set to zero in the well closing pressure recovery stage. By changing the oil well extraction or well closing state to simulate different operating conditions of the oil well, the optical fiber strain response characteristics under different production conditions of the horizontal well and the data on the change of bottom hole pressure with production time are collected. Further, the optical fiber strain data (x-axis data) and bottom hole pressure data (y-axis data) at different stages are drawn on Cartesian coordinates using data analysis software, and the strain data and pressure data of the measuring point are fitted using the least squares method to obtain the mathematical relationship between the optical fiber strain and the wellbore pressure.

[0043] In this embodiment, a single fracture is taken as an example, and the influence of temperature and wellbore flow is not considered. The oil well is shut down for 432 hours (a total of 480 hours) after producing at a fixed rate for 48 hours and then monitored. The optical fiber strain and bottom hole pressure data along the wellbore axis at different times are selected for comparative analysis, and the data at the perforation position with obvious peak strain characteristics are fitted to clarify the strain-pressure change relationship. The results are as follows: Figure 2 .

[0044] In step S500, the optical fiber strain data actually captured on site is substituted into the first relationship obtained by fitting, and the pressure distribution along the optical fiber is calculated.

[0045] Before step S500, the method further includes filtering and denoising the optical fiber strain data actually captured on site.

[0046] Specifically, the bottom hole pressure along the optical fiber (wellbore) is the bottom hole pressure of the horizontal section of the oil well, and the pressure distribution position corresponds to the position of the optical fiber monitoring point. According to the first relationship and the optical fiber strain data actually captured on site, the bottom hole pressure data can be calculated, and the bottom hole pressure change curve over time can be established to realize the distributed pressure well test analysis based on optical fiber strain monitoring.

[0047] In this embodiment, the optical fiber strain data obtained by numerical simulation is used to replace the processed field strain monitoring data, and the distributed pressure along the axis of the wellbore at different times of opening and closing the well is calculated as follows: Figure 3 , Figure 4 By drawing the well test analysis characteristic curves of the pressure change over time at different stages of bottom hole pressure drop caused by well production and shut-in pressure recovery, a distributed pressure well test analysis based on the optical fiber strain monitoring response signal in the same well is realized.

[0048] The present invention has at least the following beneficial effects: The method for calculating the distributed pressure of a fractured horizontal well based on the simulation of optical fiber strain monitoring in the same well provided by the present invention establishes a physical model of fracture fluid production and optical fiber strain monitoring, wherein the physical model of fracture fluid production and optical fiber strain monitoring includes reservoir geological parameters and fracturing construction parameters; establishes a reservoir geomechanics calculation model and a bottom hole pressure calculation model during the production of a horizontal well; based on the physical model of fracture fluid production and optical fiber strain monitoring, according to the reservoir geomechanics calculation model and the bottom hole pressure calculation model, respectively calculates the optical fiber strain data in the same well and the bottom hole pressure under different production conditions of the horizontal well; according to different production conditions of the horizontal well, the calculation model of the reservoir geomechanics calculation model and the bottom hole pressure calculation model are used to calculate the distributed pressure of the fractured ... The optical fiber strain data of the same well under the same conditions and the bottom hole pressure are used to fit the first relationship between the bottom hole pressure change and the optical fiber strain; the optical fiber strain data actually captured on site is brought into the first fitted relationship to calculate the pressure distribution along the optical fiber. In this way, a method for calculating the bottom hole pressure of a horizontal well based on the optical fiber strain data of the same well can be established, which is conducive to exploring the influence of different production states of oil wells on the stress of the bottom rock of the oil well and the flow of formation fluids, expanding the research content in related fields, and is of great significance for analyzing the changes in downhole pressure and rock stress field through strain characteristic signals, and evaluating the oil production capacity and fracturing transformation effect of the reservoir; Furthermore, according to the geological and construction parameters of the target well, the optical fiber strain response signal is simulated to clarify the influence of different downhole conditions on the optical fiber strain response and bottom hole pressure, and the correlation between optical fiber strain and bottom hole pressure is clarified. The bottom hole pressure along the axis of the wellbore at a certain moment is calculated based on the optical fiber strain response data obtained and processed on site, and the distributed bottom hole pressure is used to perform well test analysis of the subsequent production status of the fracturing well under complex formation conditions, providing decision support for the formulation of reasonable operation plans for subsequent exploitation, improving oilfield exploitation efficiency, and reducing operating costs.

[0049] Obviously, the embodiments described above are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, ordinary technicians in this field can make other different forms of changes or modifications without creative work, which should fall within the scope of protection of the present invention.

Claims

1. A method for calculating the distributed pressure of a fractured horizontal well based on the simulation of optical fiber strain monitoring in the same well, characterized in that: include: Establishing a physical model of fracture fluid production and optical fiber strain monitoring, wherein the physical model of fracture fluid production and optical fiber strain monitoring includes reservoir geological parameters and fracturing construction parameters; Establish reservoir geomechanics calculation model and bottom hole pressure calculation model during horizontal well production; Based on the physical model of fracture fluid production and optical fiber strain monitoring, according to the reservoir geomechanics calculation model and the bottom hole pressure calculation model, respectively calculate the optical fiber strain data of the same well and the bottom hole pressure under different production conditions of the horizontal well; According to the optical fiber strain data of the horizontal well under different production conditions and the bottom hole pressure, the first relationship between the bottom hole pressure change and the optical fiber strain is obtained by fitting; The optical fiber strain data actually captured on site is substituted into the first fitted equation to calculate the pressure distribution along the optical fiber.

2. The method for calculating the distributed pressure of a fractured horizontal well based on the same-well optical fiber strain monitoring simulation according to claim 1, characterized in that: In the step of establishing a reservoir geomechanics calculation model and a bottom hole pressure calculation model during horizontal well production, the reservoir geomechanics calculation model includes: Based on the principle of momentum conservation and Biot's poroelasticity theory, the equilibrium equation of rock skeleton deformation is: ；（1） When the rock undergoes a small deformation, the equation for the relationship between reservoir rock stress and strain is: ；（2） in, σ is the stress tensor, in MPa; ρ m is the rock skeleton density, in kg / m 3 ; g is the acceleration due to gravity, in m / s 2 ; σ0 is the stress tensor at the initial moment, in MPa; C is the elastic stiffness tensor; ε is the strain tensor; α is the Boit coefficient, with the unit being 1; I is the unit tensor; Φ m is the reservoir porosity; p is the pore pressure; p0 is the initial pore pressure.

3. The method for calculating the distributed pressure of a fractured horizontal well based on the simulation of optical fiber strain monitoring in the same well according to claim 1, characterized in that: In the step of establishing a reservoir geomechanics calculation model and a bottom hole pressure calculation model during horizontal well production, the bottom hole pressure calculation model includes: The flow of fluid in porous media satisfies the mass conservation equation: ； Assuming that the flow of fluid in porous media is linear and satisfies Darcy's law, the fluid flow velocity is: ； The fluid seepage in the entire reservoir is divided into two parts: flow in the rock matrix and flow in the fractures. Combining the mass conservation with Darcy's law, the seepage equations for the two parts are obtained. Among them, the governing equation of two-dimensional matrix flow is: ； The governing equation for one-dimensional fracture flow is: ； Where n is the porosity, with the unit being 1; ρ f is the fluid density in kg / m 3 ; V f is the average velocity of the fluid, in m / s; k is the formation permeability, in mD; μ is the fluid viscosity, in mPa·s; p is the pore pressure, in MPa; K m is the reservoir permeability, in m 2 ; μ is the fluid viscosity, in Pa·s; p m is the reservoir pressure, in Pa; Φ m is the reservoir porosity, with a unit of 1; C t is the comprehensive compression coefficient, in Pa -1 ; t is time, in seconds; K f is the reservoir permeability, in m 2 ; p f is the crack pressure, in Pa; l is the one-dimensional local coordinate of the crack; Φ f is the fracture porosity.

4. The method for calculating the distributed pressure of a fractured horizontal well based on the simulation of optical fiber strain monitoring in the same well according to claim 1, characterized in that: The physical model based on the fracture fluid production and optical fiber strain monitoring, according to the reservoir geomechanics calculation model and the bottom hole pressure calculation model, respectively calculates the optical fiber strain data of the same well under different production conditions of the horizontal well and the bottom hole pressure, including: According to the reservoir geomechanics calculation model and the physical model based on the fracture fluid production and optical fiber strain monitoring, the finite element method is used to calculate the optical fiber strain data of the horizontal well under different production conditions; According to the bottom hole pressure calculation model and the physical model based on the fracture fluid production and optical fiber strain monitoring, the bottom hole pressure under different production conditions of the horizontal well is calculated using the finite element method.

5. The method for calculating the distributed pressure of a fractured horizontal well based on the simulation of optical fiber strain monitoring in the same well according to claim 1, characterized in that: The step of fitting a first relationship between the bottom hole pressure change and the optical fiber strain according to the optical fiber strain data of the same well under different production conditions of the horizontal well and the bottom hole pressure comprises: According to the optical fiber strain data of the horizontal well under different production conditions and the bottom hole pressure, the curve of bottom hole pressure change and optical fiber strain is fitted; The obtained curve is plotted using data analysis software, and the data is fitted using the least squares method to obtain the first relationship.

6. The method for calculating the distributed pressure of a fractured horizontal well based on the simulation of optical fiber strain monitoring in the same well according to claim 5, characterized in that: Before the step of bringing the optical fiber strain data actually captured on site into the first relationship obtained by fitting to calculate the pressure distribution along the optical fiber, the method further includes: The optical fiber strain data actually captured on site is processed through filtering and noise reduction.

7. The method for calculating the distributed pressure of a fractured horizontal well based on the simulation of optical fiber strain monitoring in the same well according to claim 5, characterized in that: The first relational expression is a linear equation of two variables.

8. The method for calculating the distributed pressure of a fractured horizontal well based on the simulation of optical fiber strain monitoring in the same well according to claim 1, characterized in that: The reservoir geological parameters include ground stress parameters, rock elastic modulus, Poisson's ratio, and permeability; The fracturing construction parameters include the spacing and number of clusters of artificial fractures formed by fracturing.

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