Analysis method for flow-induced vibration of injection and production gas of directional well gas storage and reliability of tubular column

Abstract

The invention discloses a directional well gas storage injection-production gas flow-induced vibration and tubular column reliability analysis method, which comprises vibration displacement calculation and time-varying reliability analysis, and the vibration displacement calculation comprises the following steps: carrying out mechanical analysis on an injection-production tubular column infinitesimal element, and substituting force into an injection-production tubular column vibration model to obtain a time-varying reliability analysis result; vibration displacement in the gas storage injection-production pipe production process is solved through a finite element method; the time-varying reliability analysis comprises the steps that a bearing capacity attenuation model and a load random process model are established, and the influence of gas impact load random process correlation on the time-varying reliability of the injection-production string structure is analyzed based on a Monte Carlo simulation method. According to the method, the theoretical problem that three-dimensional nonlinear flow-induced vibration caused by changes of the hole drift angle and the azimuth angle and buckling contact loads of the injection-production string and the casing pipe are not considered in the existing theory can be solved, and the time-varying reliability of the injection-production string is analyzed according to the obtained random loads.

Description

Technical Field

[0001] The present invention relates to the technical field of petroleum and natural gas engineering, and in particular to a method for analyzing vibration caused by injection and production gas flow in a directional well gas storage reservoir and reliability of a pipe string. Background Art

[0002] In recent years, with the growing demand for natural gas, the scale of gas storage construction has continued to expand. During production, gas storage facilities operate with high injection and production volumes. High-velocity gas flow within the pipes induces intense vibrations in the tubing. These vibrations interact with the gas, creating coupled vibrations that can cause fatigue and wear, directly impacting the lifespan and safety of the injection and production tubing. The injection and production tubing is the sole link between underground gas storage and the surface natural gas transmission network, making its safety extremely important and a key research topic. To ensure the safety of the injection and production tubing and guarantee safe operation in gas storage facilities, extensive research has been conducted both domestically and internationally over the years.

[0003] Currently, several methods are used domestically and internationally to analyze the vibration of gas storage injection and production strings. First, numerical simulation and simulation: Finite element software is used to build segmented or full-scale fluid-structure interaction models of the injection and production string to simulate and analyze the coupled vibration between the injection and production string and the high-velocity gas, thereby optimizing string design and operating parameters. However, numerical simulation is costly, requires extensive computing resources, and has a long cycle time. Second, experimental research: Physical models are used to simulate actual operating conditions in gas storage facilities to observe and measure the string's vibration behavior under different operating conditions. While experimental research can provide practical data, it is costly, involving equipment, materials, and human resources, and it is difficult to simulate all actual operating conditions. Third, theoretical analysis: Current vibration models of gas storage injection and production strings only consider the effects of gas kinetic energy, suspension forces, and internal and external string pressure on vibration. They fail to account for variations in well inclination and azimuth, as well as the effects of contact loads between the injection and production string and casing, including buckling. Furthermore, conventional tubing string reliability analysis relies on traditional casing reliability analysis methods and fails to consider time-varying reliability.

[0004] In existing patents, most of them are methods for monitoring the stress, vibration characteristics, string integrity and string sealing of gas storage injection and production strings. Moreover, the theoretical models in existing literature are all two-dimensional vibration models. The situations considered in the models are relatively simple and cannot meet the accuracy requirements. Therefore, it is necessary to propose an analysis method for the vibration caused by gas flow in directional well gas storage injection and production and the reliability of the string. Summary of the Invention

[0005] In order to solve the above problems, the present invention proposes a method for analyzing the flow-induced vibration and tubing reliability of directional well gas storage reservoirs, so as to solve the theoretical problem that the existing theory does not take into account the changes in well inclination and azimuth, and the three-dimensional nonlinear flow-induced vibration caused by the buckling contact load between the injection and production tubing and casing. The random load obtained in this way is used to analyze the time-varying reliability of the injection and production tubing.

[0006] The technical solution adopted in the present invention is as follows:

[0007] A method for analyzing gas flow-induced vibration and string reliability in a directional well gas storage reservoir includes:

[0008] Vibration displacement calculation: Conduct mechanical analysis on the injection and production string microelement, substitute the force into the injection and production string vibration model, and use the finite element method to solve the vibration displacement of the injection and production string during the production process of the gas storage reservoir;

[0009] Time-varying reliability analysis: A bearing capacity attenuation model and a load random process model are established. Based on the Monte Carlo simulation method, the impact of the random process correlation of gas impact load on the time-varying reliability of the injection and production string structure is analyzed.

[0010] Furthermore, the mechanical analysis of the injection and production string microelement includes: taking the injection and production string microelement segment as the research object, approximately regarding the injection and production string microelement segment as a straight segment, establishing a three-dimensional rectangular coordinate system, and performing mechanical analysis on the injection and production string microelement; the z-axis of the three-dimensional rectangular coordinate system is vertically downward, the x-axis is horizontally to the right, and the y-axis satisfies the right-hand rule; then the displacement field functions u1, u2, and u3 corresponding to the x, y, and z directions of the three-dimensional rectangular coordinate system can be expressed as:

[0011]

[0012] Where: w x , w y , w z Respectively represent the displacement of the injection and production string in the x, y, and z directions, in meters; x and y are the horizontal coordinates, in meters; t is the time, in seconds.

[0013] Furthermore, the loads acting on the micro-element section of the injection and production string include: the impact force of high-speed gas on the injection and production string, the contact force between the injection and production string and the casing, the axial force, and the imaginary tension generated by the pressure difference between the fluid inside and outside the injection and production string.

[0014] Furthermore, the method for calculating the high-speed gas impact force on the injection and production string includes:

[0015] Taking into account the influence of changes in well inclination and azimuth on the injection and production string, the impact force of high-speed gas on the injection and production string can be expressed as:

[0016]

[0017] Where: f is the gas density in kg / m 3 ; A i is the cross-sectional area of ​​the inner diameter of the injection and production string, in m 2 ; V is the gas flow rate, in m / s; α1, α2 are the well inclination angles corresponding to the upper and lower micro-segments, in rad; is the azimuth angle corresponding to the upper and lower micro segments, in rad; F x , F y , F z It is the gas impact force in the x, y, and z directions, in N.

[0018] Furthermore, the well inclination and azimuth at any well depth are obtained by using the cubic spline interpolation method, where the interval [s k -1,s k The function expressions of well inclination and azimuth in ] are:

[0019]

[0020] in:

[0021] M i =a″ i ,i=k,k-1;

[0022] Where: k is the measurement point number, k = 1, 2, ..., N; L k is the length of the measuring section, L k =s k -s k-1 , unit is m; s is the well depth at the interpolation point, unit is m; N is the number of measuring points.

[0023] Furthermore, the method for calculating the contact force between the injection and production string and the casing includes:

[0024]

[0025] Where: δ is the deformation caused by the contact between the injection and production string and the casing, in m; F is the contact force between the injection and production string and the casing, in N; E is the elastic modulus of the injection and production tube material, in Pa; R1 and R2 are the radii of the casing and the injection and production string, respectively, in m; f is the friction force between the injection and production string and the casing, in N; μ is the friction coefficient.

[0026] Furthermore, the calculation method of the additional contact force between the injection and production string and the casing includes:

[0027] For the case of sinusoidal buckling of the injection and production string, no additional contact force is generated;

[0028] For the helical buckling of injection and production strings, considering the influence of well inclination, the load calculation formula for the helical buckling of injection and production strings in inclined wellbores is as follows:

[0029]

[0030] Where: F H is the critical load of the injection and production string for helical sinusoidal buckling, in N; n is the half-wave number of the injection and production string buckling deformation, which is related to the string length L; r′ is the apparent radius, half of the distance between the inner wall of the casing and the outer wall of the injection and production string, in m; E is the elastic modulus of the injection and production string, in Pa; I is the moment of inertia of the injection and production string, in m 4 ;

[0031] The critical helical buckling load of the injection and production string in the vertical well section is calculated using the following model:

[0032]

[0033] The critical helical buckling of the injection and production string in the curved section is analyzed based on the differential equation of an elastic rod in three-dimensional space. After simplification, the following formula is obtained:

[0034]

[0035] Where: k is the wellbore curvature;

[0036] Therefore, the additional contact force in the case of helical buckling of the injection and production string can be expressed as:

[0037]

[0038] Where: F add is the additional contact force caused by the buckling of the injection and production string, in N; T is the axial compression force of the injection and production string, i.e. the effective force, in N.

[0039] Furthermore, in the injection and production string vibration model, linear Lagrange interpolation function and cubic Hermite difference function are used to represent the longitudinal displacement and two lateral displacements of the injection and production string, and the discretized displacement function is substituted into the unit string vibration control equation to obtain a discrete form dynamic equation; the discrete form dynamic equation includes the overall displacement matrix, mass matrix, damping matrix, stiffness matrix and load column vector of the structure.

[0040] Furthermore, in the time-varying reliability analysis, within the service life T of the injection and production string, the gas impact force is discretized into a random load model S(t) using the Poisson process, and the correlation coefficient of the gas impact load process in the time domain is calculated using the Pearson correlation:

[0041]

[0042] Where: k is a constant that characterizes the rate at which correlation decays over time.

[0043] Furthermore, in the time-varying reliability analysis, the bearing capacity attenuation model can be expressed as:

[0044] R(t)=R0g(t)

[0045] Where: R(t) is the bearing capacity, g(t) is the attenuation function, and R0 is the initial bearing capacity of the injection and production string. The bearing capacity attenuation function can be selected according to the material, service environment, and damage mechanism of the injection and production string.

[0046] The beneficial effects of the present invention are:

[0047] 1. Based on the existing technology, the present invention simplifies the actual injection and production string with a tubing hanger at the upper end and a packer at the lower end to a fixed situation at both ends. Compared with the simplified model with one end fixed and the other end simply supported, the boundary conditions of the model of the present invention are more in line with the actual situation, thereby improving the calculation accuracy of the model.

[0048] 2. The present invention takes into account the vibration response of the oil pipe caused by airflow impact due to changes in well inclination and azimuth. Compared with the lateral fluid-solid coupling model that only considers the lateral bending deformation caused by gas kinetic energy and gas pressure, and the longitudinal fluid-solid coupling model derived from the four-equation model, this model is closer to the actual situation of injection and production string vibration during gas storage production, and increases the applicability of the model.

[0049] 3. Building on existing technologies, this invention considers displacements of the injection and production string in the x, y, and z directions, representing a three-dimensional vibration problem. Compared to two-dimensional vibration models, this improves model accuracy and produces results that are closer to reality. Furthermore, to ensure the proper operation of the gas storage facility, an analysis method for the impact of random loads on the time-varying reliability of the structure is introduced. This method can be used to analyze the impact of the random nature of gas impact forces on the time-varying reliability of the injection and production string, thereby assessing its structural reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 The present invention is a flowchart of a method for analyzing gas flow-induced vibration and string reliability in a directional well gas storage reservoir according to an embodiment of the present invention. DETAILED DESCRIPTION

[0051] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. That is, the embodiments described are only part of the embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0052] This embodiment provides an analysis method for gas flow-induced vibration and tubing reliability in directional well gas storage facilities. This method addresses the theoretical problem that existing theories fail to account for changes in well inclination and azimuth, as well as the three-dimensional nonlinear flow-induced vibration caused by contact loads between the injection and production tubing and casing, and the impact of random loads on the time-varying reliability of the injection and production tubing. The analysis method includes vibration displacement calculation and time-varying reliability analysis. The vibration displacement calculation includes: performing a mechanical analysis of the injection and production tubing microelement, substituting the force into the injection and production tubing vibration model, and using the finite element method to solve the vibration displacement of the gas storage injection and production tubing during production. The time-varying reliability analysis includes: establishing a bearing capacity attenuation model and a load random process model, and using Monte Carlo simulation methods to analyze the impact of the random process correlation of gas impact loads on the time-varying reliability of the injection and production tubing structure. The specific analysis is as follows.

[0053] S1: Calculate the vibration displacement of the injection and production pipes during the production process of the gas storage reservoir.

[0054] Taking the injection and production string micro-element segment as the research object, the micro-element segment can be approximated as a straight segment. A three-dimensional rectangular coordinate system is established to conduct a mechanical analysis of the micro-element of the injection and production string. The loads acting on the micro-element segment mainly include: the impact force of high-speed gas on the injection and production string, the contact force between the injection and production string and the casing, the axial force, and the imaginary tension caused by the pressure difference between the fluid inside and outside the injection and production string.

[0055] The expressions of displacement field functions u1, u2, u3 corresponding to the global coordinate system x, y, z are:

[0056]

[0057] Where: w x , w y , w z Respectively represent the displacement of the injection and production string in the x, y, and z directions, in meters; x and y are the horizontal coordinates, in meters; t is the time, in seconds.

[0058] Then, the kinetic energy T, potential energy U, and external work W of the injection and production string are expressed as:

[0059]

[0060]

[0061]

[0062] Where: s is the density of the injection and production string (kg / m 3 );m s , m f are the mass of the injection and production string and gas per unit length, kg; are the first-order derivatives of the displacement of the oil pipe in three directions with time; w′ x , w′ y and w″ x ,w″ y are the first-order and second-order derivatives of the lateral displacement of the oil pipe with z, respectively; A is the cross-sectional area of ​​the oil pipe, m 2 ; V is the gas velocity in the pipe, m / s; I is the moment of inertia of the oil pipe, m 4 ; E is the elastic modulus of the oil pipe, Pa; f(z, t), p(z, t) and q(z, t) are the external forces in the x, y and z directions of the oil pipe, N respectively.

[0063] Substitute the kinetic energy T, potential energy U, and external work W of the injection and production string into the Hamilton variational principle. The three-dimensional nonlinear flow-induced vibration control equations of the unit injection and production string in the x, y, and z directions can be obtained, specifically:

[0064] x-direction:

[0065]

[0066] y direction:

[0067]

[0068] z-direction:

[0069]

[0070] Mechanical analysis of micro-element sections of injection and production strings:

[0071] The loads acting on the micro-element section of the injection and production string mainly include: the impact force of high-speed gas on the injection and production string, the contact force between the injection and production string and the casing, the axial force, and the imaginary tension caused by the pressure difference between the fluid inside and outside the injection and production string.

[0072] (1) Axial force of the injection and production string F, N;

[0073] (2) The fictitious tension P0A0-P generated by the pressure difference between the fluid inside and outside the string i A i , MPa;

[0074] Where: P0, P i are the annulus pressure and the pipe pressure, MPa respectively; A0 is the cross-sectional area of ​​the outer diameter of the pipe string.

[0075] (3) Impact force of high-speed gas in the injection and production pipe

[0076] When high-speed gas flows through the injection and production pipe and the well inclination and azimuth change, it will produce impact force on the pipe string, causing the injection and production pipe string to vibrate. The impact force can be expressed by the following formula:

[0077]

[0078] Where: f is the gas density in kg / m 3 ; A i is the cross-sectional area of ​​the inner diameter of the injection and production string, in m 2 ; V is the gas flow rate, in m / s; α1, α2 are the well inclination angles corresponding to the upper and lower micro-segments, in rad; is the azimuth angle corresponding to the upper and lower micro segments, in rad; F x , F y , F z It is the gas impact force in the x, y, and z directions, in N.

[0079] Since the gas shock load is related to the wellbore trajectory, the cubic spline interpolation method can be used to calculate the well inclination and azimuth at any well depth. k -1,s k The specific expression of the well inclination function is:

[0080]

[0081] in:

[0082] M i =a″ i ,i=k,k-1;

[0083] Where: k is the measurement point number, k = 1, 2, ..., N; L k is the length of the measuring section, L k =s k -s k-1 , unit is m; s is the well depth at the interpolation point, unit is m; N is the number of measuring points.

[0084] (4) Contact force between injection and production string and casing

[0085] The contact force between the injection and production string and the casing can be expressed as:

[0086]

[0087] Where: δ is the deformation caused by the contact between the injection and production string and the casing, in m; F is the contact force between the injection and production string and the casing, in N; E is the elastic modulus of the injection and production tube material, in Pa; R1 and R2 are the radii of the casing and the injection and production string, respectively, in m; f is the friction force between the injection and production string and the casing, in N; μ is the friction coefficient.

[0088] Considering the sinusoidal buckling case, no additional contact forces are generated.

[0089] Considering the helical buckling situation, additional contact forces are generated.

[0090] The load calculation formula for the helical buckling of the injection and production string in an inclined wellbore is as follows, which can take into account the influence of the well inclination angle:

[0091]

[0092] Where: F H is the critical load of the injection and production string for helical sinusoidal buckling, in N; n is the half-wave number of the injection and production string buckling deformation, which is related to the string length L; r′ is the apparent radius, half of the distance between the inner wall of the casing and the outer wall of the injection and production string, in m; E is the elastic modulus of the injection and production string, in Pa; I is the moment of inertia of the injection and production string, in m 4 .

[0093] The critical helical buckling load of the injection and production string in the vertical well section is calculated using the following model:

[0094]

[0095] The critical helical buckling of the injection and production string in the curved section is analyzed based on the differential equation of the elastic rod in three-dimensional space. After simplification, the following formula can be obtained:

[0096]

[0097] Where: k is the wellbore curvature.

[0098] Therefore, the additional contact force in the case of helical buckling of the injection and production string can be expressed as:

[0099]

[0100] Where: F add is the additional contact force caused by the buckling of the injection and production string, in N; T is the axial compression force of the injection and production string, i.e. the effective force, in N.

[0101] The additional contact force of the injection and production string is related to the axial force of the injection and production string, so an iterative solution is required.

[0102] (5) Boundary conditions and initial conditions of the injection and production string

[0103] The constraint boundaries of the injection and production string with the tubing hanger at the upper end and the packer at the lower end are simplified to fixed supports, and the initial state is static. The boundary conditions and initial conditions can be expressed as:

[0104] Boundary conditions:

[0105]

[0106] Initial conditions:

[0107]

[0108] (6) Solution of injection and production string vibration model

[0109] The linear Lagrange interpolation function and the cubic Hermite difference function are used to represent the longitudinal displacement and two lateral displacements of the injection and production string respectively. The finite element discretization form can be expressed as follows:

[0110]

[0111] Where:

[0112]

[0113]

[0114]

[0115]

[0116] Where: l is the length of the unit; d is the displacement matrix of the string unit; ψ x , ψ y , ψ z are the two lateral and longitudinal displacement shape function matrices of the string element respectively.

[0117] Substituting the discretized displacement function into the unit string vibration control equation, the discrete form dynamic equation of the system can be obtained:

[0118]

[0119] Where: S, M, C, K, Q are the overall displacement matrix, mass matrix, damping matrix, stiffness matrix and load column vector of the structure respectively. Specifically:

[0120]

[0121] in:

[0122] The Newmark-β method is used to solve the discrete form dynamic equations by step-by-step integration.

[0123] The calculation process of the Newmark-β method is as follows:

[0124] ① Give the equilibrium equation of the system in incremental form

[0125] t i+1 The dynamic equation at the moment is:

[0126] t i The dynamic equation at the moment is:

[0127] When the time step Δt is small enough, it is considered that at t i -t i+1 The system is linear in the interval, and the increment of the equilibrium equation is:

[0128]

[0129] ② The effective stiffness is calculated by using the incremental Newmark-β method. Payload increment and displacement increment Δu i Perform step-by-step integration to solve

[0130]

[0131] Where:

[0132]

[0133]

[0134] ③ Obtain the displacement increment Δu i Then, calculate t i+1 Total displacement, acceleration, and velocity at time:

[0135]

[0136] The solution method is not limited to the Newmark-β method, and a piecewise analytical method, a central difference method, a Wilson-θ integral method or a time domain explicit method may also be used.

[0137] S2: Analyze the impact of the random process of gas impact force on the time-varying reliability of the injection and production string.

[0138] During the production process of a gas storage facility, the bearing capacity and gas impact force of the injection and production string change with time, which can be expressed as R(t) and S(t), respectively. The bearing capacity R(t) can usually be expressed as: R(t) = R0g(t), where: R0 is the initial bearing capacity of the injection and production string, and g(t) is the attenuation function. The bearing capacity attenuation function can be selected according to the material, service environment and damage mechanism of the injection and production string.

[0139] During the service life T of the injection and production string, the gas impact force can be discretized using the Poisson process to form a random load model S(t), and the correlation coefficient of the gas impact load process in the time domain can be calculated using the Pearson correlation:

[0140]

[0141] During the service life T of the injection and production string, it is assumed that n load events occur, which are recorded as S i , the corresponding occurrence time is t i , i=1,2,…,n, its cumulative probability function is F S (), then the reliability of the injection-production string within the service time T can be expressed as:

[0142]

[0143] If the number of loads n is regarded as a random variable, the load process S can be described by the Poisson process. i ,i=1,2,…,n, then:

[0144]

[0145] Taking into account the randomness of the initial bearing capacity R0, its probability density function is recorded as f0(r), and the reliability of the injection-production string can be further expressed as:

[0146]

[0147] When the probability distribution of the initial bearing capacity R0 and the attenuation function g(t) are given, the Monte Carlo simulation method can be used to analyze the influence of the random process correlation of the gas impact load on the time-varying reliability, such as Figure 1 As shown, the simulation method is briefly described as the following steps:

[0148] (1) Generate a sample value r0 of the initial bearing capacity R0;

[0149] (2) Generate the number n of load events that follow the Poisson distribution within time T;

[0150] (3) Generate n times t uniformly distributed within T i , i=1, 2, …, n;

[0151] (4) Generate the time corresponding to t i n gas shock load samples s i (It is known that its probability distribution function is F S ()), i = 1, 2, ... n. If the gas shock load process is independent, n independent F S () load sample; if not independent, first generate the load s1 at time t1, then determine the load s2 at time t2 by s1 and the time difference t2-t1, and so on, determine s3, s4, ..., s n

[0152] (5) Calculate t i The bearing capacity value r(t i )=r0g(t i ),i=1,2,…n. If for i=1,2,…n, r(t i )…s i If the above equation is true, the injection and production string is safe; otherwise, the structure fails.

[0153] (6) Repeat steps (1) to (5) M times. If the number of times the structure is safe is m, then when M is large enough, the reliability of the structure can be approximated by m / M.

[0154] It should be noted that, for the sake of simplicity, the aforementioned method embodiments are described as a series of action combinations. However, those skilled in the art should be aware that this application is not limited by the order of the actions described, because according to this application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in this specification are all preferred embodiments, and the actions and modules involved are not necessarily required by this application.

Claims

1. A method for analyzing gas flow-induced vibration and string reliability in a directional well gas storage reservoir, characterized in that: include: Vibration displacement calculation: Conduct mechanical analysis on the injection and production string microelement, substitute the force into the injection and production string vibration model, and use the finite element method to solve the vibration displacement of the injection and production string during the production process of the gas storage reservoir; Time-varying reliability analysis: A bearing capacity attenuation model and a load random process model are established. Based on the Monte Carlo simulation method, the impact of the random process correlation of gas impact load on the time-varying reliability of the injection and production string structure is analyzed.

2. The method for analyzing gas flow-induced vibration and string reliability of a directional well gas storage reservoir according to claim 1, characterized in that: The mechanical analysis of the injection and production string microelement includes: taking the injection and production string microelement segment as the research object, approximately regarding the injection and production string microelement segment as a straight segment, establishing a three-dimensional rectangular coordinate system, and performing mechanical analysis on the injection and production string microelement; the z-axis of the three-dimensional rectangular coordinate system is vertically downward, the x-axis is horizontally to the right, and the y-axis satisfies the right-hand rule; then the displacement field functions u1, u2, and u3 corresponding to the x, y, and z directions of the three-dimensional rectangular coordinate system can be expressed as: Where: w x , w y , w z Respectively represent the displacement of the injection and production string in the x, y, and z directions, in meters; x and y are the horizontal coordinates, in meters; t is the time, in seconds.

3. The method for analyzing gas flow-induced vibration and string reliability of a directional well gas storage reservoir according to claim 2, characterized in that: The loads acting on the micro-element section of the injection and production string include: the impact force of high-speed gas on the injection and production string, the contact force between the injection and production string and the casing, the axial force, and the imaginary tension caused by the pressure difference between the fluid inside and outside the injection and production string.

4. The method for analyzing gas flow-induced vibration and string reliability of a directional well gas storage reservoir according to claim 3, characterized in that: The calculation method of the high-speed gas impact force on the injection and production string includes: Taking into account the influence of changes in well inclination and azimuth on the injection and production string, the impact force of high-speed gas on the injection and production string can be expressed as: Where: f is the gas density in kg / m 3 ; A i is the cross-sectional area of ​​the inner diameter of the injection and production string, in m 2 ; V is the gas flow rate, in m / s; α1, α2 are the well inclination angles corresponding to the upper and lower micro-segments, in rad; is the azimuth angle corresponding to the upper and lower micro segments, in rad; F x , F y , F z It is the gas impact force in the x, y, and z directions, in N.

5. The method for analyzing gas flow-induced vibration and string reliability of a directional well gas storage reservoir according to claim 4, characterized in that: The inclination and azimuth of any well depth are calculated by cubic spline interpolation method, where the interval [s k -1,s k The function expressions of well inclination and azimuth in ] are: in: M i =a″ i ,i=k,k-1; Where: k is the measurement point number, k = 1, 2, ..., N; L k is the length of the measuring section, L k =s k -s k-1 , unit is m; s is the well depth at the interpolation point, unit is m; N is the number of measuring points.

6. The method for analyzing gas flow-induced vibration and string reliability of a directional well gas storage reservoir according to claim 3, characterized in that: The method for calculating the contact force between the injection and production string and the casing includes: Where: δ is the deformation caused by the contact between the injection and production string and the casing, in m; F is the contact force between the injection and production string and the casing, in N; E is the elastic modulus of the injection and production tube material, in Pa; R1 and R2 are the radii of the casing and the injection and production string, respectively, in m; f is the friction force between the injection and production string and the casing, in N; μ is the friction coefficient.

7. The method for analyzing gas flow-induced vibration and string reliability of a directional well gas storage reservoir according to claim 6, characterized in that: The calculation method of the additional contact force between the injection and production string and the casing includes: For the case of sinusoidal buckling of the injection and production string, no additional contact force is generated; For the helical buckling of injection and production strings, considering the influence of well inclination, the load calculation formula for the helical buckling of injection and production strings in inclined wellbores is as follows: Where: F H is the critical load of the injection and production string for helical sinusoidal buckling, in N; n is the half-wave number of the injection and production string buckling deformation, which is related to the string length L; r′ is the apparent radius, half of the distance between the inner wall of the casing and the outer wall of the injection and production string, in m; E is the elastic modulus of the injection and production string, in Pa; I is the moment of inertia of the injection and production string, in m 4 ; The critical helical buckling load of the injection and production string in the vertical well section is calculated using the following model: The critical helical buckling of the injection and production string in the curved section is analyzed based on the differential equation of an elastic rod in three-dimensional space. After simplification, the following formula is obtained: Where: k is the wellbore curvature; Therefore, the additional contact force in the case of helical buckling of the injection and production string can be expressed as: Where: F add is the additional contact force caused by the buckling of the injection and production string, in N; T is the axial compression force of the injection and production string, i.e. the effective force, in N.

8. The method for analyzing gas flow-induced vibration and string reliability of a directional well gas storage reservoir according to claim 1, characterized in that: In the injection and production string vibration model, a linear Lagrange interpolation function and a cubic Hermite difference function are used to represent the longitudinal displacement and two lateral displacements of the injection and production string. The discretized displacement function is substituted into the unit string vibration control equation to obtain a discrete form dynamic equation. The discrete form dynamic equations include the overall displacement matrix, mass matrix, damping matrix, stiffness matrix and load column vector of the structure.

9. The method for analyzing gas flow-induced vibration and string reliability of a directional well gas storage reservoir according to claim 1, characterized in that: In the time-varying reliability analysis, within the service life T of the injection and production string, the gas impact force is discretized into a random load model S(t) using the Poisson process, and the correlation coefficient of the gas impact load process in the time domain is calculated using the Pearson correlation: Where: k is a constant that characterizes the rate at which correlation decays over time.

10. The method for analyzing gas flow-induced vibration and string reliability of a directional well gas storage reservoir according to claim 1, characterized in that: In the time-varying reliability analysis, the bearing capacity attenuation model can be expressed as: R(t)=R0g(t) Where: R(t) is the bearing capacity, g(t) is the attenuation function, and R0 is the initial bearing capacity of the injection and production string. The bearing capacity attenuation function can be selected according to the material, service environment, and damage mechanism of the injection and production string.

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