A method for long open hole section multifunctional integrated pipe string process parameter optimization

Abstract

This invention relates to the field of oil well development technology, specifically disclosing a method for optimizing process parameters of a multifunctional integrated tubing string for long open-hole sections. The method includes: establishing an eccentric non-uniform annular flow channel model; establishing a rheological parameter correction relationship with temperature variation and calculating corrected rheological parameters; calculating the friction gradient along the flow path based on geometric eccentricity and annular flow cross-sectional area; determining the maximum safe discharge rate based on the corrected rheological parameters and friction gradient along the flow path; calculating the cuttings carrying ratio under different circulation discharge rates and determining the minimum cuttings carrying rate; determining the drilling circulation discharge rate based on the maximum safe discharge rate and the minimum cuttings carrying rate; determining the actual axial load of the tubing string based on the buckling critical load; and determining the cementing displacement discharge rate within the displacement discharge optimization search range based on the cement slurry volume ratio threshold. This method for optimizing process parameters of a multifunctional integrated tubing string for long open-hole sections solves the problem that current parameter designs merely satisfy parameters for a single stage.

Description

Technical Field

[0001] This invention relates to the field of oil well development technology, and more specifically, to a method for optimizing process parameters of a multifunctional integrated tubing string for long open-hole sections. Background Technology

[0002] As oil and gas development expands into low-permeability and marginal reservoirs—areas with limited exploitability—cost reduction and efficiency improvement have become crucial for ensuring economical development. Multifunctional integrated tubing string technology, by combining multiple drilling and completion processes, can significantly shorten the operation cycle and is an effective means of achieving low-cost development. However, its application faces severe challenges in operations on long open-hole wells with complex trajectories. Due to the long open-hole section and complex well trajectory, the tubing string experiences extremely harsh stress and fluid environments downhole. Improperly designed process parameters can easily lead to operation failure.

[0003] The operation of multi-functional integrated tubing strings involves a deep coupling of hydraulics, tubing mechanics, and cementing technology, with complex constraints between various physical field parameters. In long open-hole sections, the tubing string is severely eccentric due to the wellbore trajectory, easily forming cuttings beds. Increasing the circulation rate is necessary to ensure wellbore cleanliness, but this significantly increases the equivalent circulation density, which can easily induce lost circulation in formations with narrow safety density windows. The integrated tubing string has a complex structure and large stiffness variations, facing enormous friction during the long open-hole run-in process, making it prone to sinusoidal or helical buckling or even self-locking. Modifying fluid properties to reduce friction may affect cementing displacement efficiency or wellbore stability. Therefore, traditional parameter design, which only satisfies parameters for one aspect, may compromise the stability of other aspects, leading to unsuccessful run-in or substandard cementing quality. Summary of the Invention

[0004] In order to overcome the shortcomings of the existing technology, the present invention provides a highly adaptable track power box structure, which aims to solve the problems in the above-mentioned existing technology.

[0005] The technical solution adopted by this invention to solve its technical problem is: a method for optimizing process parameters of a multifunctional integrated tubing column with a long naked eye segment, comprising the following steps: S1: Obtain the original inclination data of the target well and construct the wellbore geometry matrix. ; Collect physical properties of tubing components and form a tubing-wellbore coupling matrix. ; According to the matrix sum matrix Calculate geometric eccentricity Circulation cross-sectional area Thickness of wide gap area and narrow gap thickness Establish an eccentric non-uniform annular flow channel model; Then, the hydrostatic pressure of the eccentric non-uniform annular flow channel model under static conditions was determined. and the original temperature of the strata ; S2: Based on the original formation temperature and the thermal properties of the tubing string, a three-dimensional unsteady heat conduction model of the casing-annulus-formation is established, and the fluid temperature field distributed with well depth inside the casing is obtained by solving the model. and the fluid temperature field distributed in the annulus with well depth ; According to the temperature field and Establish the correction relationship of rheological parameters with temperature, calculate the corrected rheological parameters; then, based on geometric eccentricity... and the cross-sectional area of ​​the annular circulation Calculate the friction gradient along the friction path; S3: Based on the corrected rheological parameters and friction gradient along the formation, calculate the equivalent circulating density ECD(z) under different circulating displacements, and then calculate the ECD(z) and formation fracture pressure. Determine the maximum safe displacement ; Based on modified rheological parameters and an eccentric non-uniform annular flow channel model, the cuttings transport ratio (CTR) under different circulation rates was calculated. A wellbore cleanliness threshold was set, and the minimum cuttings transport rate was determined. ; S4: Based on tubing-wellbore coupling matrix Determine the critical buckling load Based on equivalent circulating density ECD(z) and wellbore geometry Establish a segmented friction model to determine the actual axial load on the tubing string. ; S5: Based on maximum safe displacement and minimum rock-carrying capacity Determine drilling circulation flow rate Based on buckling critical load and the actual axial load of the tubing Calculate the safety factor for axial load on the tubular column. ; S6: Based on corrected rheological parameters and determined actual axial load on the tubing string The actual eccentric position of the tubing was obtained later. Determine the cement slurry volume ratio, and then determine the cementing displacement rate within the optimal displacement rate search range based on the cement slurry volume ratio threshold. .

[0006] It is worth noting that in step S1, the original inclination data of the target well includes the depth (MD) and the inclination angle at the calculation node extracted from the wellbore geometry matrix. and azimuth First, calculate the total angle change rate and radius of curvature of adjacent measuring points, and then measure the depth of the entire well section according to the set step size. Discretize into N computational nodes; then the discretized... The depth measurements of each calculation node are converted into spatial geometric parameters. The vertical depth, north coordinate, and east coordinate of each calculation node are obtained by accumulating displacement increments. Simultaneously, the total angle change rate k of each calculation node is calculated to construct the wellbore geometric matrix. .

[0007] Preferably, in step S1, the physical properties of the tubing assembly include tubing mechanical parameters and thermophysical parameters, wherein the tubing mechanical parameters include the elastic modulus. Moment of inertia The centerline of the air is heavy Packer characteristic outer diameter Thermophysical parameters include thermal conductivity, specific heat capacity, and density of the tubular material. The physical properties of the tubing assembly at different depths (MD) are retrieved and mapped one by one to computational nodes with the same MD, thus obtaining the tubing-wellbore coupling matrix. .

[0008] Optionally, in step S1, the wellbore geometry matrix is ​​entered using the depth MD as the index key. Coupled matrix with tubing string-wellbore The splicing process yields a splicing matrix; the measured wellbore diameter is then imported into each computation node. and the outer diameter of the tubing Geometric eccentricity of each computation node Cross-sectional area of ​​the annular flow at each computing node Thickness of wide gap region Narrow gap region thickness ;in , which is the geometric eccentricity between the center of the tubing string and the center of the target wellbore.

[0009] Specifically, in step S1, the preset drilling fluid design density of the target well is extracted. and the preset geothermal gradient Calculate the hydrostatic pressure at each computation node under static conditions. and the original temperature of the strata , , Where z is a computation node, To calculate the vertical depth of node z, The surface ambient temperature, This is the acceleration due to gravity.

[0010] It is worth noting that, in step S2, the equation set corresponding to the casing-annulus-formation three-dimensional unsteady heat conduction model is as follows: ;in, The temperature of the fluid inside the pipe. The annular fluid temperature, The heat transfer coefficient inside the pipe is... The annular heat transfer coefficient is... For the cycle time, For calculation nodes, i.e., depth measurement; This represents the rate of change of the fluid temperature inside the pipe over time. It represents the rate of change of the annular fluid temperature over time, reflecting the unsteady-state characteristics of heat transfer; This represents the friction gradient along the pipe caused by the axial flow of the fluid inside the pipe. This represents the frictional temperature gradient generated by axial flow in the annular fluid. The fluid velocity inside the pipe. The velocity of the annular fluid. The inner radius of the tubular column, Let be the radius of the target well wall. The specific heat capacity of the circulating fluid. The mass flow rate of the circulating fluid; The original formation temperature; the thermal properties of the tubing include the internal heat transfer coefficient. and annular heat transfer coefficient ; Based on the heat transfer coefficient inside the pipe at each calculation node and annular heat transfer coefficient Calculate the fluid temperature inside the pipe corresponding to this calculation node. and annular fluid temperature The temperature of the fluid inside the pipe The fluid temperature field distributed with well depth inside the pipe is obtained by arranging the calculation nodes in the correct order. , to increase the temperature of the annular fluid The arrangement of the computational nodes yields the fluid temperature field distributed in the annulus with well depth. ; Obtain the fluid consistency coefficient under normal temperature reference conditions on the ground. With flow index Based on the physical fact that high temperatures in the long naked-eye section cause fluid thinning, the obtained fluid temperature inside the pipe is... and annular fluid temperature As the independent variable, a rheological parameter correction relationship is established as a function of temperature, and this rheological parameter correction relationship satisfies an exponential decay model: Consistency coefficient correction: ; Flow index correction: ; In the formula, Consistency coefficient corrects rheological parameters. To correct the rheological parameters for the flow index, The actual fluid temperature at each computational node is used when correcting rheological parameters with either the consistency coefficient or the flow index within the computational tube. When calculating the rheological parameters corrected for annular consistency coefficient or annular flowability index , Ground reference temperature The consistency temperature decay coefficient is calibrated through rheological experiments. The temperature compensation coefficient for the flow index, calibrated through rheological experiments; Will adopt or The calculated consistency coefficient corrected rheological parameters and flow index-corrected rheological parameters The geometric eccentricity output by the eccentric non-uniform annular flow channel model described in step S1 and the cross-sectional area of ​​the annular circulation Combined, calculate the friction gradient along the path considering temperature variations. Its calculation formula is: In the formula, For the depth integral variable, The actual measured wellbore diameter, The outer diameter of the tubular column, To correct the rheological parameters for the consistency coefficient, To correct the rheological parameters for the flow index, For a given cycle displacement, Based on geometric eccentricity Eccentricity correction coefficient, eccentricity correction coefficient .

[0011] Preferably, in step S3, the friction gradient along the friction line is analyzed. The equivalent circulation density ECD(z) for each computation node z under different circulation displacements is obtained by integral calculation. In the formula, For the depth measurement of the current computing node, For the depth integral variable, The friction gradient along the path, The static density of the fluid under reference conditions. It is the acceleration due to gravity. The vertical depth of the current computing node; The formation fracturing pressure corresponding to each calculation node As a constraint boundary, all computational nodes are extracted to satisfy... The maximum displacement value under certain conditions is used as the maximum safe displacement. .

[0012] Optionally, in step S3, a solid-liquid two-phase flow debris transport model is established based on the modified rheological parameters and the eccentric non-uniform annular flow channel model. The equations of the model are as follows: ,in The volume concentration of rock fragments in the suspended layer. This represents the volume concentration of rock fragments in the dispersed layer. This represents the volume fraction of rock cuttings. The average volume concentration of rock fragments in the annular section. The reference volume concentration of the suspended layer during the iteration process. The reference volume concentration of the cuttings bed during the iteration process; The total cross-sectional area of ​​the annular space is [missing information]. This represents the effective cross-sectional area of ​​the suspended flow channel. The characteristic transport velocity of the mixed phase within the suspension layer. The local wellbore inclination angle at the calculation node is obtained from the wellbore geometry matrix; When solving the equations of this model, the initial amount of rock cuttings generated by the drill bit cutting through the formation is used as the source boundary condition for the material input, and the circulating displacement is also considered. Consistency coefficient corrected rheological parameters Flow index corrected rheological parameters Geometric eccentricity and the cross-sectional area of ​​the annular flow Substituting these variables into the model as the independent variables determining the fluid's suspension and rock-carrying capacity, where... , , This represents the maximum critical volume fraction of the cuttings bed. Based on the principle of volume conservation, the carrying efficiency of the fluid for cuttings under different flow velocities and viscosities is analyzed to determine the distribution ratio of the suspended and dispersed cuttings layers within the cross-section. and The relationship is then used to ultimately determine the average rock cuttings volume concentration at the annular cross-section corresponding to different calculation nodes. ; The cyclic displacement will increase sequentially. As the input condition, the solid-liquid two-phase flow cuttings transport model is iteratively simulated, and the average volume concentration of cuttings in the annular section corresponding to each calculation node is solved in each iteration. and the reference volume concentration of the suspension layer Then, the cuttings transport ratio at each calculation node was further calculated under different cycle displacements. ; The rock cuttings carrying ratio By traversing all calculation nodes throughout the entire well section using this formula, a distribution curve of cuttings transport ratio under different circulation discharge rates is generated. Using a cuttings transport ratio (CTR) greater than or equal to the wellbore cleanliness threshold as a search criterion, the lowest discharge point satisfying this criterion is identified in the cuttings transport ratio distribution curves under different circulation discharge rates, and this point is determined as the minimum cuttings-carrying discharge rate. .

[0013] Specifically, in step S4, based on the tubing-wellbore coupling matrix elastic modulus and moment of inertia The critical buckling load corresponding to each computational node of the tubing under different buckling modes in the long naked eye segment was calculated. The calculation formula is: ,in The buckling mode order is... The effective length of the calculation unit; Based on the equivalent cyclic density distribution ECD(z) obtained in step S3, and combined with the physical properties of the tubing assembly, the effective buoyancy linear load of the tubing at each calculation node is calculated. Its calculation formula satisfies In the formula, The linear weight per unit length of the tubing in air. The density of the tubular material; the physical properties of the tubular assembly include the linear weight per unit length of the column in air. and column material density ; Based on equivalent circulation density and wellbore geometry A piecewise friction model is established, and the equations of the model are as follows: ,in The coefficient of friction, For the wellbore support force of a conventional tubing section, This refers to the additional contact normal force generated by the rigidity of the tubing. This is the additional friction function generated by the packer due to its high rigidity and small clearance. The inclination angle at the computational node is extracted from the wellbore geometry matrix. Let be the length of the discrete micro-segment of the tubing at each computation node. The characteristic outer diameter of the packer inserted into the tubing string. The total frictional resistance during the process of running the tubing into the target well; Then, the effective buoyancy line load of each calculation node is... Total frictional resistance during the process of running the tubing into the target well By superimposing the data, the actual axial loads at each calculation node can be obtained. .

[0014] Preferably, in step S6, the actual eccentric position of the tubing string is... The calculation process includes: taking the actual axial load of the tubing determined in step S4. Input to the tubing-wellbore coupling matrix In the calculation, the radial flexural displacement of each node is calculated. This allows us to obtain the corrected actual eccentricity position of the tubing. ; Corrected actual string eccentricity positions for each calculation node The rheological parameters are then converted into three-dimensional spatial geometric boundary conditions and corrected using the consistency coefficient obtained in step S2. and flow index-corrected rheological parameters Substitute the cement slurry-isolation fluid-drilling fluid into the three-dimensional multiphase flow displacement model to solve the problem and determine the volume ratio of cement slurry at the annular multiphase flow interface. The process of substituting the cement slurry-separating fluid-drilling fluid into a three-dimensional multiphase flow displacement model and determining the volume percentage of cement slurry at the annular multiphase flow interface includes: The equations for the three-dimensional multiphase flow displacement model of cement slurry-separating fluid-drilling fluid are as follows: , For shear stress, , The radial coordinates of the annular flow channel are: For the depth integral variable, Let be the velocity component of the fluid in the radial direction. This represents the main filling velocity component of the fluid in the axial direction. To calculate the local fluid phase density within the grid, The model focuses on the influence of fluid pressure on the displacement interface, taking into account the density difference, viscosity difference, and annular eccentricity between fluids under high-temperature conditions in deep wells. To determine the volume percentage of cement slurry at the annular multiphase flow interface, the equation will be used. The obtained flow velocity field Substituting into the multiphase flow volume fraction transport equation based on the VOF method Solve in the middle, where This represents the volume percentage of cement slurry at the annular multiphase flow interface. To replace time; Preset replacement displacement optimal search range While ensuring that the equivalent circulating density is always less than the corresponding formation fracture pressure Under the premise of obtaining the cement slurry volume ratio change map of the displacement displacement within the preferred displacement displacement search interval, and selecting the cement slurry volume ratio change map with a cement slurry volume ratio greater than or equal to the cement slurry volume ratio threshold from these cement slurry volume ratio change maps, and taking the displacement displacement corresponding to the selected cement slurry volume ratio change map as the cementing displacement displacement. .

[0015] The beneficial effects of this invention are as follows: In the method for optimizing process parameters of a multi-functional integrated tubing string for long open-hole sections, a multi-physics coupling model of hydraulics, tubing mechanics, and cementing process is constructed. Specifically, a combination of hydraulic process parameters is constructed in step S3, a combination of mechanical process parameters is constructed in step S4, and a combination of cementing process parameters is constructed in step S6. By using the multi-physics coupling model combined with sensitivity analysis, the comprehensive impact of each parameter on wellbore cleanliness, tubing string safety, and cementing quality is quantified. This simultaneously takes into account cuttings transport efficiency, tubing string running safety, and cementing displacement quality, avoiding stability problems caused by a single engineering objective, thereby ensuring smooth running and cementing quality. Attached Figure Description

[0016] Figure 1 A flowchart for the method of optimizing process parameters for a long naked-eye segment multifunctional integrated tubular column.

[0017] Figure 2 This is a schematic diagram of a multifunctional integrated tubular column structure.

[0018] Figure 3 The graph shows the variation of equivalent circulating density with well depth under different circulating discharge rates.

[0019] Figure 4 This is a graph showing the distribution of cuttings transport ratio under different cycle displacements.

[0020] Figure 5 The graph shows the effective stress and buckling characteristic curves of the tubing string under different wellbore curvatures.

[0021] Figure 6 The graph shows the change in the volume ratio of cement slurry under different displacement rates. Detailed Implementation

[0022] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0023] Combination Figures 1 to 6 The method for optimizing process parameters of a multifunctional integrated tubing column with a long naked-eye section, as shown, includes the following steps: S1: Obtain the original inclination data of the target well and construct the wellbore geometry matrix. ; Collect physical properties of tubing components and form a tubing-wellbore coupling matrix. ; According to the matrix sum matrix Calculate geometric eccentricity Circulation cross-sectional area Thickness of wide gap area and narrow gap thickness An eccentric non-uniform annular flow channel model reflecting the characteristics of wellbore enlargement and tubing eccentricity was established. Then, the hydrostatic pressure of the eccentric non-uniform annular flow channel model under static conditions (t=0) is determined. and the original temperature of the strata ; S2: Based on the original formation temperature and the thermal properties of the tubing string, a three-dimensional unsteady heat conduction model of the casing-annulus-formation is established, and the fluid temperature field distributed with well depth inside the casing is obtained by solving the model. and the fluid temperature field distributed in the annulus with well depth ; According to the temperature field and Establish the correction relationship of rheological parameters with temperature, calculate the corrected rheological parameters; then, based on geometric eccentricity... and the cross-sectional area of ​​the annular circulation Calculate the friction gradient along the friction path; S3: Based on the corrected rheological parameters and friction gradient along the formation, calculate the equivalent circulating density ECD(z) under different circulating displacements, and then calculate the ECD(z) and formation fracture pressure. Determine the maximum safe displacement ; Based on modified rheological parameters and an eccentric non-uniform annular flow channel model, the cuttings transport ratio (CTR) under different circulation rates was calculated. A wellbore cleanliness threshold was set, and the minimum cuttings transport rate was determined. ; S4: Based on tubing-wellbore coupling matrix Determine the critical buckling load Based on equivalent circulating density ECD(z) and wellbore geometry Establish a segmented friction model to determine the actual axial load on the tubing string. ; S5: Based on maximum safe displacement and minimum rock-carrying capacity Determine drilling circulation flow rate Based on buckling critical load and the actual axial load of the tubing Calculate the safety factor for axial load on the tubular column. ; S6: Based on corrected rheological parameters and determined actual axial load on the tubing string The actual eccentric position of the tubing was obtained later. Determine the cement slurry volume ratio, and then determine the cementing displacement rate within the optimal displacement rate search range based on the cement slurry volume ratio threshold. ; In the method for optimizing process parameters of multi-functional integrated tubing string for long open-hole sections, a multi-physics coupling model of hydraulics, tubing mechanics, and cementing process is constructed. Specifically, a combination of hydraulic process parameters is constructed in step S3, a combination of mechanical process parameters is constructed in step S4, and a combination of cementing process parameters is constructed in step S6. By using the multi-physics coupling model in conjunction with sensitivity analysis, the comprehensive impact of each parameter on wellbore cleanliness, tubing string safety, and cementing quality is quantified. This simultaneously takes into account cuttings transport efficiency, tubing string running safety, and cementing displacement quality, avoiding stability issues caused by a single engineering objective, thereby ensuring smooth running and cementing quality.

[0024] It is worth noting that in step S1, the original inclination data of the target well includes the depth (MD) and the inclination angle at the calculation node extracted from the wellbore geometry matrix. and azimuth First, calculate the total angle variation rate and radius of curvature of adjacent measuring points. Discretize the depth MD of the entire well section into N calculation nodes according to a set step size (e.g., 1m). Then, convert the depths of the N discretized calculation nodes into spatial geometric parameters. Calculate the vertical depth, north coordinate, and east coordinate of each calculation node by accumulating displacement increments, and simultaneously calculate the total angle variation rate k of each calculation node to construct the wellbore geometric matrix. The wellbore geometry matrix uses depth as the row index, and the column vectors are vertical depth, north coordinate, east coordinate, inclination angle, azimuth angle, and total angle change rate, thus establishing the precise position and shape vector of each calculation node in three-dimensional space.

[0025] The calculation steps for the rate of change of the full angle and the radius of curvature are as follows: First, calculate the spatial angle between two adjacent measuring points (denoted as measuring point 1 and measuring point 2). The calculation formula satisfies: , The well inclination angle at measuring point 1, The well inclination angle at measuring point 2, Let be the azimuth of measuring point 1. The azimuth of measuring point 2; then combined with the depth measurement increment between the two measuring points. Calculate the total angle change rate of adjacent measuring points. and radius of curvature .

[0026] Based on this, the depth measurement (MD) of the entire well section is discretized into N calculation nodes according to a set step size. Subsequently, based on the minimum curvature method, the depth measurements of each discretized calculation node are converted into spatial geometric parameters, and the vertical depth of each calculation node is calculated by accumulating displacement increments. North coordinates and East Coordinates The formulas for calculating the displacement increment between two adjacent nodes are as follows: Vertical depth increment: ; North coordinate increment: ; East coordinate increment: ; in, Based on the spatial angle The determined dog leg smoothing coefficient satisfies .

[0027] Specifically, in step S1, the physical properties of the tubing assembly include tubing mechanical parameters and thermophysical parameters, wherein the tubing mechanical parameters include the elastic modulus. Moment of inertia The centerline of the air is heavy Packer characteristic outer diameter Thermophysical parameters include thermal conductivity, specific heat capacity, and density of the tubular material. The physical properties of the tubing assembly at different depths (MD) are retrieved and mapped one by one to computational nodes with the same MD, thus obtaining the tubing-wellbore coupling matrix. In this step, the centerline of the tubing unit is forced to coincide with the centerline of the target well's wellbore trajectory, thereby ignoring initial positional differences and forming a tubing-wellbore coupling matrix that incorporates non-uniform stiffness and weight distribution characteristics. Specifically, to address the issue of inconsistency between the tubing coordinates and the wellbore coordinates of the target well, the geodetic rectangular coordinate system of the wellbore geometric model of the target well is uniformly adopted.

[0028] Optionally, in step S1, the wellbore geometry matrix is ​​entered using the depth MD as the index key. Coupled matrix with tubing string-wellbore The splicing process yields a splicing matrix; the measured wellbore diameter is then imported into each computation node. and the outer diameter of the tubing Based on the gravity settlement effect of the deviated well section, assuming the tubing string is attached to the bottom edge of the target wellbore, the geometric eccentricity of each calculation node is... Cross-sectional area of ​​the annular flow at each computing node Thickness of wide gap region Narrow gap region thickness ;in , which is the geometric eccentricity between the center of the tubing string and the center of the target wellbore.

[0029] Preferably, in step S1, the preset drilling fluid design density of the target well is extracted. and the preset geothermal gradient Based on the principles of hydrostatics and the geothermal distribution patterns of the formation, the hydrostatic pressure of each calculation node under static conditions is calculated. and the original temperature of the strata , , Where z is a computation node, To calculate the vertical depth of node z, The surface ambient temperature, This is the acceleration due to gravity.

[0030] Specifically, in step S2, the equation set corresponding to the casing-annulus-formation three-dimensional unsteady heat conduction model is as follows: ;in, The temperature of the fluid inside the pipe. The annular fluid temperature, The heat transfer coefficient inside the pipe is... The annular heat transfer coefficient is... For the cycle time, For calculation nodes, i.e., depth measurement; This represents the rate of change of the fluid temperature inside the pipe over time. It represents the rate of change of the annular fluid temperature over time, reflecting the unsteady-state characteristics of heat transfer; This represents the friction gradient along the pipe caused by the axial flow of the fluid inside the pipe. This represents the frictional temperature gradient generated by axial flow in the annular fluid. The fluid velocity inside the pipe. The velocity of the annular fluid. The inner radius of the tubular column, Let be the radius of the target well wall. The specific heat capacity of the circulating fluid. The mass flow rate of the circulating fluid; The initial formation temperature serves as the initial boundary condition for wellbore-formation heat exchange, driving the radial heat transfer process; the tubing's thermophysical parameters include the in-tube heat transfer coefficient. and annular heat transfer coefficient The heat transfer coefficient is calculated using a multi-layer cylindrical wall thermal resistance series model, which integrates the thermal resistance of the pipe and the heat transfer coefficient of the fluid convection. Based on the heat transfer coefficient inside the pipe at each calculation node and annular heat transfer coefficient Calculate the fluid temperature inside the pipe corresponding to this calculation node. and annular fluid temperature The temperature of the fluid inside the pipe The fluid temperature field distributed with well depth inside the pipe is obtained by arranging the calculation nodes in the correct order. , to increase the temperature of the annular fluid The arrangement of the computational nodes yields the fluid temperature field distributed in the annulus with well depth. ; Obtain the fluid consistency coefficient under normal temperature reference conditions on the ground. With flow index Based on the physical fact that high temperatures in the long naked-eye section cause fluid thinning, the obtained fluid temperature inside the pipe is... and annular fluid temperature As the independent variable, a correction relationship for rheological parameters as a function of temperature is established, and the correction relationship for rheological parameters satisfies the following exponential decay model: Consistency coefficient correction: ; Flow index correction: ; In the formula, Consistency coefficient corrects rheological parameters. To correct the rheological parameters for the flow index, The actual fluid temperature at each computational node is used when correcting rheological parameters with either the consistency coefficient or the flow index within the computational tube. When calculating the rheological parameters corrected for annular consistency coefficient or annular flowability index , Ground reference temperature The consistency temperature decay coefficient is calibrated through rheological experiments. The temperature compensation coefficient for the flow index, calibrated through rheological experiments; Will adopt or The calculated consistency coefficient corrected rheological parameters and flow index-corrected rheological parameters The geometric eccentricity output by the eccentric non-uniform annular flow channel model described in step S1 and the cross-sectional area of ​​the annular circulation Combined, calculate the friction gradient along the path considering temperature variations. Its calculation formula is: In the formula, For the depth integral variable, The actual measured wellbore diameter, The outer diameter of the tubular column, To correct the rheological parameters for the consistency coefficient, To correct the rheological parameters for the flow index, For a given cycle displacement, Based on geometric eccentricity The eccentricity correction coefficient is calculated using the following empirical polynomial. Geometric eccentricity The larger, The smaller the value, the more it indicates that the eccentricity causes a change in the local flow velocity in the annulus, thereby reducing the overall friction; in this embodiment, the calculation formula is... time and Preferably, annular fluid temperature is used As Perform the calculation.

[0031] It is worth noting that in step S3, the friction gradient along the friction line is calculated. The equivalent circulation density ECD(z) for each computation node z under different circulation displacements is obtained by integral calculation. In the formula, For the depth measurement of the current computing node, For the depth integral variable, The friction gradient along the path, The static density of the fluid under reference conditions. It is the acceleration due to gravity. This represents the vertical depth of the current computation node. Based on ECD(z), the following is obtained: Figure 3 The graph shows the equivalent circulating density as a function of well depth under different circulating displacements. The formation fracturing pressure corresponding to each calculation node As a constraint boundary, all computational nodes are extracted to satisfy... The maximum displacement value under certain conditions is used as the maximum safe displacement. .

[0032] Preferably, in step S3, based on the modified rheological parameters and the eccentric non-uniform annular flow channel model, and considering the characteristics of low flow velocity and easy rock debris deposition in the large annular space of the long open-hole section, a solid-liquid two-phase flow rock debris transport model is established. The equations of the model are as follows: ,in The volume concentration of rock fragments in the suspended layer. This represents the volume concentration of rock fragments in the dispersed layer. This represents the volume fraction of rock cuttings. The average volume concentration of rock fragments in the annular section. The reference volume concentration of the suspended layer during the iteration process. The reference volume concentration of the cuttings bed during the iteration process; The total cross-sectional area of ​​the annular space is [missing information]. This represents the effective cross-sectional area of ​​the suspended flow channel. The characteristic transport velocity of the mixed phase within the suspension layer. The local wellbore inclination angle at the calculation node is obtained from the wellbore geometry matrix; When solving the equations of this model, the initial amount of rock cuttings generated by the drill bit cutting through the formation is used as the source boundary condition for the material input, and the circulating displacement is also considered. Consistency coefficient corrected rheological parameters Flow index corrected rheological parameters Geometric eccentricity and the cross-sectional area of ​​the annular flow Substituting these variables into the model as the independent variables determining the fluid's suspension and rock-carrying capacity, where... , , To determine the maximum critical volume fraction of rock cuttings in the bed, an empirical constant of 0.55–0.65 is selected. Based on the principle of volume conservation, the carrying efficiency of the fluid for rock cuttings at different flow velocities and viscosities is analyzed to determine the distribution ratio of suspended and dispersed rock cuttings within the cross-section. and The relationship is then used to ultimately determine the average rock cuttings volume concentration at the annular cross-section corresponding to different calculation nodes. ; The cyclic displacement will increase sequentially. As the input condition, the solid-liquid two-phase flow cuttings transport model is iteratively simulated, and the average volume concentration of cuttings in the annular section corresponding to each calculation node is solved in each iteration. and the reference volume concentration of the suspension layer Then, the cuttings transport ratio at each calculation node was further calculated under different cycle displacements. ; The rock cuttings carrying ratio This formula is used to iterate through all calculation nodes of the entire well section, generating results such as... Figure 4 The graph shows the distribution curves of cuttings transport ratio under different cycle displacements; A wellbore cleanliness qualification threshold of 90% was set. Using a cuttings transport ratio (CTR) greater than or equal to this threshold as a search criterion, the lowest discharge rate point satisfying this criterion was identified in the cuttings transport ratio distribution curves under different circulation discharge rates. This lowest discharge rate was then determined as the minimum cutter-carrying discharge rate. .

[0033] Optionally, in step S4, based on the tubing-wellbore coupling matrix elastic modulus and moment of inertia The critical buckling load corresponding to each computational node of the tubing under different buckling modes in the long naked eye segment was calculated. The calculation formula is: ,in The buckling mode order is... The effective length of the calculation unit is used. In this embodiment, the buckling modes include sinusoidal buckling and helical buckling. When the buckling mode is sinusoidal buckling, the effective length of the calculation unit is determined. Calculate the critical buckling load When the buckling mode is helical buckling, the following is adopted: Calculate the critical buckling load Specifically, when the actual axial force exceeds this critical value, the tubing will experience buckling instability of a corresponding form. For example... Figure 5 The graphs shown represent the effective stress and buckling characteristic curves of the tubing string under different wellbore curvatures. The actual axial load of the tubing string is calculated from these curves. With the above-mentioned critical buckling load Perform a comparative analysis of the entire well section; if the actual axial load is greater than the buckling critical load (i.e., the data point falls into the range of 100°C), then the analysis will be conducted. Figure 5 If the red high-risk zone is identified, it indicates a risk of helical buckling and potential self-locking hazards. In this case, the wellbore trajectory needs to be adjusted through the feedback loop or the high-efficiency drag-reducing fluid needs to be replaced until the safe running conditions are met.

[0034] In step S4, based on the equivalent cyclic density distribution ECD(z) obtained in step S3, and combined with the physical properties of the tubing assembly, the effective buoyancy line load of the tubing at each calculation node is calculated. Its calculation formula satisfies In the formula, The linear weight per unit length of the tubing in air. The density of the tubular material; the physical properties of the tubular assembly include the linear weight per unit length of the column in air. and column material density As can be seen from this formula, the effective buoyancy of the tubing is directly affected by the dynamic equivalent cyclic density. Based on equivalent circulation density and wellbore geometry A piecewise friction model is established, and the equations of the model are as follows: ,in The coefficient of friction, For the wellbore support force of a conventional tubing section, This refers to the additional contact normal force generated by the rigidity of the tubing. This is the additional friction function generated by the packer due to its high rigidity and small clearance. The inclination angle at the computational node is extracted from the wellbore geometry matrix. Let be the length of the discrete micro-segment of the tubing at each computation node. The characteristic outer diameter of the packer inserted into the tubing string. The total frictional resistance during the process of running the tubing into the target well serves as the boundary condition for the tubing's stress and is used in subsequent steps to calculate the actual axial load on the tubing. Then, the effective buoyancy line load of each calculation node is... Total frictional resistance during the process of running the tubing into the target well By superimposing the data, the actual axial loads at each calculation node can be obtained. .

[0035] It is worth noting that in step S6, the actual eccentric position of the tubing string... The calculation process includes: The actual axial load of the tubing determined in step S4 Input to the tubing-wellbore coupling matrix In the calculation, the radial flexural displacement of each node is calculated. This allows us to obtain the corrected actual eccentricity position of the tubing. The specific calculation steps are as follows: Based on the measured wellbore diameter at the current node With the outer diameter of the tubing Calculate the radial clearance of each computation node. Based on the Euler-Bernoulli beam bending theory, the tubing-wellbore coupling matrix is ​​used. The bending stiffness is based on the actual axial load of the tubular column. The boundary conditions are determined by combining the critical buckling load obtained in step S4. Calculate the radial flexural displacement after deformation under stress. ; To conform to the actual space constraints downhole, this radial deflection displacement The calculation satisfies the following judgment rule: (1) When the node is in a state of compressive buckling (i.e., axial pressure) When the tubing buckles and comes into contact with the wellbore wall, the radial deflection displacement is... Take the maximum radial clearance on one side between the outer wall of the tubing string and the inner wall of the wellbore. ,Right now ; (2) When the node is in a tensile or low axial compression section where buckling has not occurred (i.e., axial pressure) When the column is subjected to the lateral component of the effective linear weight, it will experience bending deflection. The bending sagging of this section of the foundation is calculated using a tension beam mechanical model. The amount of bending and sagging of the foundation The calculation formula is: In the formula, The effective linear weight of the tubular string in the fluid; The inclination angle at the computational node is extracted from the wellbore geometry matrix; Length of discrete element between nodes; For the bending stiffness of the tubular column; This represents the actual axial load on the tubular column at that node. Let be the Euler reference load for this discrete element, where ; With radial clearance For the maximum constraint boundary, take Subsequently, based on the calculated radial deflection displacement of each node... Obtain the actual eccentric position of the tubing after considering stress deformation. In the formula, This provides the initial geometric eccentricity in the tubing-wellbore coupling matrix.

[0036] Corrected actual string eccentricity positions for each calculation node The rheological parameters are then converted into three-dimensional spatial geometric boundary conditions and corrected using the consistency coefficient obtained in step S2. and flow index-corrected rheological parameters Substitute the cement slurry-isolation fluid-drilling fluid into the three-dimensional multiphase flow displacement model to solve the problem and determine the volume ratio of cement slurry at the annular multiphase flow interface. The process of substituting the cement slurry-separating fluid-drilling fluid into a three-dimensional multiphase flow displacement model and determining the volume percentage of cement slurry at the annular multiphase flow interface includes: The equations for the three-dimensional multiphase flow displacement model of cement slurry-separating fluid-drilling fluid are as follows: , For shear stress, , The radial coordinates of the annular flow channel are: For the depth integral variable, Let be the velocity component of the fluid in the radial direction. This represents the main filling velocity component of the fluid in the axial direction. To calculate the local fluid phase density within the grid, The model focuses on the influence of fluid pressure on the displacement interface, taking into account the density difference, viscosity difference, and annular eccentricity between fluids under high-temperature conditions in deep wells. To determine the volume percentage of cement slurry at the annular multiphase flow interface, the equation will be used. The obtained flow velocity field Substituting into the multiphase flow volume fraction transport equation based on the VOF method Solve in the middle, where This represents the volume percentage of cement slurry at the annular multiphase flow interface. This is to replace the time.

[0037] Based on the volume ratio of cement slurry at the annular multiphase flow interface, the following is obtained: Figure 6 The graph shown illustrates the variation of cement slurry volume percentage under different displacement rates, illustrating the changing pattern of cement slurry volume percentage under different displacement rates. Based on the rated displacement capacity of the cementing equipment and the bottom hole safety pressure window, a pre-set optimal displacement search range is established. While ensuring that the equivalent circulating density is always less than the corresponding formation fracture pressure Under the premise of obtaining the cement slurry volume ratio change map of the displacement displacement within the preferred displacement displacement search interval, and selecting the cement slurry volume ratio change map that is greater than or equal to the cement slurry volume ratio threshold (e.g., 95%) from these cement slurry volume ratio change maps, and taking the displacement displacement corresponding to the selected cement slurry volume ratio change map as the cementing displacement displacement. This allows for optimal control of cementing quality.

[0038] This scheme also includes step S7: obtaining the three-pressure profile of the formation in the working well: pore pressure, fracture pressure, and stress profile. and collapse pressure Determine the basic safety density window Equivalent cyclic density Including drilling fluid static density And the annular frictional additional equivalent density generated by the circulation displacement Q, the drilling circulation displacement determined in step S5 Substitute formation safety constraints Q in the context confirms the drilling fluid density. .

[0039] Finally, based on the buckling critical load obtained in step S4 The drilling circulation displacement obtained in step S5 The cementing displacement obtained in step S6 The drilling fluid density obtained in step S7 To determine the process model for the multifunctional integrated tubular column used in the long naked eye segment.

[0040] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for long open hole section multifunctional integrated string process parameter optimization, characterized in that, Includes the following steps: S1 : Obtain the original survey data of the target well and construct a wellbore geometry matrix ; Acquiring physical properties of a pipe string assembly and forming a pipe string - wellbore coupling matrix ; According to the matrix and the matrix Calculate the geometric eccentricity , annulus flow area , wide gap zone thickness and narrow gap zone thickness , establish eccentric non-uniform annulus flow channel model; The hydrostatic pressure of eccentric non-uniform annular flow channel model in static state is then determined and the original temperature of the formation ; S2: according to the formation original temperature and the pipe string thermal physical parameters, a casing-annulus-formation three-dimensional unsteady heat conduction model is established, and a fluid temperature field distributed with well depth in the pipe is solved and a fluid temperature field distributed with well depth in the annulus ; According to the temperature field and Establish the relationship between rheological parameters and temperature, calculate the corrected rheological parameters, and then calculate the corrected rheological parameters based on geometric eccentricity. and the cross-sectional area of ​​the annular circulation Calculate the friction gradient along the friction path; S3: Based on the corrected rheological parameters and friction gradient along the formation, calculate the equivalent circulating density ECD(z) under different circulating displacements, and then calculate the ECD(z) and formation fracture pressure. Determine the maximum safe displacement ; Based on modified rheological parameters and an eccentric non-uniform annular flow channel model, the cuttings transport ratio (CTR) under different circulation rates was calculated. A wellbore cleanliness threshold was set, and the minimum cuttings transport rate was determined. ; S4: Based on tubing-wellbore coupling matrix Determine the critical buckling load ; Based on equivalent circulating density ECD(z) and wellbore geometry Establish a segmented friction model to determine the actual axial load on the tubing string. ; S5: Based on maximum safe displacement and minimum rock-carrying capacity Determine drilling circulation flow rate Based on buckling critical load and the actual axial load of the tubing Calculate the safety factor for axial load on the tubular column. ; S6: Based on corrected rheological parameters and determined actual axial load on the tubing string The actual eccentric position of the tubing was obtained later. Determine the cement slurry volume ratio, and then determine the cementing displacement rate within the optimal displacement rate search range based on the cement slurry volume ratio threshold. .

2. The method for optimizing process parameters of a multifunctional integrated tubular column for long naked-eye segments according to claim 1, characterized in that: In step S1, the original inclination data of the target well includes the depth (MD) and the inclination angle at the calculated node extracted from the wellbore geometry matrix. and azimuth First, calculate the total angle change rate and radius of curvature of adjacent measuring points, and then measure the depth of the entire well section according to the set step size. Discretize into N computational nodes; then the discretized... The depth measurements of each calculation node are converted into spatial geometric parameters. The vertical depth, north coordinate, and east coordinate of each calculation node are obtained by accumulating displacement increments. Simultaneously, the total angle change rate k of each calculation node is calculated to construct the wellbore geometric matrix. .

3. The method for optimizing process parameters of a multifunctional integrated tubular column for long naked-eye segments according to claim 2, characterized in that: In step S1, the physical properties of the tubing assembly include tubing mechanical parameters and thermophysical parameters, wherein the tubing mechanical parameters include the elastic modulus. Moment of inertia The centerline of the air is heavy Packer characteristic outer diameter Thermophysical parameters include thermal conductivity, specific heat capacity, and density of the tubular material. ; The physical properties of the tubing assembly at different depths (MD) are retrieved and mapped one by one to computational nodes with the same MD, thus obtaining the tubing-wellbore coupling matrix. .

4. The method for optimizing process parameters of a multifunctional integrated tubular column for long naked-eye segments according to claim 3, characterized in that: In step S1, the wellbore geometry matrix is ​​entered using the depth MD as the index key. Coupled matrix with tubing string-wellbore The splicing process yields a splicing matrix; the measured wellbore diameter is then imported into each computation node. and the outer diameter of the tubing Geometric eccentricity of each computation node Cross-sectional area of ​​the annular flow at each computing node Thickness of wide gap region Narrow gap region thickness ;in , which is the geometric eccentricity between the center of the tubing string and the center of the target wellbore.

5. The method for optimizing process parameters of a multifunctional integrated tubular column for long naked-eye segments according to claim 4, characterized in that: In step S1, the preset drilling fluid design density of the target well is extracted. and the preset geothermal gradient Calculate the hydrostatic pressure at each computation node under static conditions. and the original temperature of the strata , , Where z is a computation node, To calculate the vertical depth of node z, The surface ambient temperature, This is the acceleration due to gravity.

6. The method for optimizing process parameters of a multifunctional integrated tubular column for long naked-eye segments according to claim 5, characterized in that: In step S2, the equation set corresponding to the casing-annulus-formation three-dimensional unsteady heat conduction model is as follows: ;in, The temperature of the fluid inside the pipe. The annular fluid temperature, The heat transfer coefficient inside the pipe is... The heat transfer coefficient of the annulus is... For the cycle time, For calculation nodes, i.e., depth measurement; This represents the rate of change of the fluid temperature inside the pipe over time. It represents the rate of change of the annular fluid temperature over time, reflecting the unsteady-state characteristics of heat transfer; This represents the friction gradient along the pipe caused by the axial flow of the fluid inside the pipe. This represents the frictional temperature gradient generated by axial flow in the annular fluid. The fluid velocity inside the pipe. The velocity of the annular fluid. The inner radius of the tubular column, Let be the radius of the target well wall. The specific heat capacity of the circulating fluid. The mass flow rate of the circulating fluid; The original formation temperature; the thermal properties of the tubing include the internal heat transfer coefficient. and annular heat transfer coefficient ; Based on the heat transfer coefficient inside the pipe at each calculation node and annular heat transfer coefficient Calculate the fluid temperature inside the pipe corresponding to this calculation node. and annular fluid temperature The temperature of the fluid inside the pipe The fluid temperature field distributed with well depth inside the pipe is obtained by arranging the calculation nodes in the correct order. , to increase the temperature of the annular fluid The arrangement of the computational nodes yields the fluid temperature field distributed in the annulus with well depth. ; Obtain the fluid consistency coefficient under normal temperature reference conditions on the ground. With flow index Based on the physical fact that high temperatures in the long naked-eye section cause fluid thinning, the obtained fluid temperature inside the pipe is... and annular fluid temperature As the independent variable, a rheological parameter correction relationship is established as a function of temperature, and this rheological parameter correction relationship satisfies an exponential decay model: Consistency coefficient correction: ; Flow index correction: ; In the formula, Consistency coefficient corrects rheological parameters. To correct the rheological parameters for the flow index, The actual fluid temperature at each computational node is used when correcting rheological parameters with either the consistency coefficient or the flow index within the computational tube. When calculating the rheological parameters corrected for annular consistency coefficient or annular flowability index , Ground reference temperature, The consistency temperature decay coefficient is calibrated through rheological experiments. The temperature compensation coefficient for the flow index, calibrated through rheological experiments; Will adopt or The calculated consistency coefficient corrected rheological parameters and flow index-corrected rheological parameters The geometric eccentricity output by the eccentric non-uniform annular flow channel model described in step S1 and the cross-sectional area of ​​the annular circulation Combined, calculate the friction gradient along the path considering temperature variations. Its calculation formula is: In the formula, For the depth integral variable, The actual measured wellbore diameter, The outer diameter of the tubular column, To correct the rheological parameters for the consistency coefficient, To correct the rheological parameters for the flow index, For a given cycle displacement, For geometric eccentricity Eccentricity correction coefficient, eccentricity correction coefficient .

7. The method for optimizing process parameters of a multifunctional integrated tubular column for long naked-eye segments according to claim 6, characterized in that: In step S3, by adjusting the friction gradient along the friction path... The equivalent circulation density ECD(z) for each computation node z under different circulation displacements is obtained by integral calculation. In the formula, For the depth measurement of the current computing node, For the depth integral variable, The friction gradient along the friction line. The static density of the fluid under reference conditions. It is the acceleration due to gravity. The vertical depth of the current calculation node; The formation fracturing pressure corresponding to each calculation node As a constraint boundary, all computational nodes are extracted to satisfy... The maximum displacement value under certain conditions is used as the maximum safe displacement. .

8. The method for optimizing process parameters of a multifunctional integrated tubular column for long naked-eye segments according to claim 7, characterized in that: In step S3, a solid-liquid two-phase flow debris transport model is established based on the modified rheological parameters and the eccentric non-uniform annular flow channel model. The equations of the model are as follows: ,in The volume concentration of rock fragments in the suspended layer. This represents the volume concentration of rock fragments in the dispersed layer. This represents the volume fraction of rock cuttings. The average volume concentration of rock fragments in the annular section. The reference volume concentration of the suspended layer during the iteration process. The reference volume concentration of the cuttings bed during the iteration process; The total cross-sectional area of ​​the annular space is [missing information]. This represents the effective cross-sectional area of ​​the suspended flow channel. The characteristic transport velocity of the mixed phase within the suspension layer. The local wellbore inclination angle at the calculation node is obtained from the wellbore geometry matrix; When solving the equations of this model, the initial amount of rock cuttings generated by the drill bit cutting through the formation is used as the source boundary condition for the material input, and the circulating displacement is also considered. Consistency coefficient corrected rheological parameters Flow index corrected rheological parameters Geometric eccentricity and the cross-sectional area of ​​the annular flow Substituting these variables into the model as the independent variables determining the fluid's suspension and rock-carrying capacity, where... , , The maximum critical volume fraction of the cuttings bed; Based on the principle of volume conservation, the efficiency of fluid carrying rock cuttings under different flow velocities and viscosities is analyzed to determine the distribution ratio of suspended and dispersed rock cuttings within the cross-section. and The relationship is then used to ultimately determine the average rock cuttings volume concentration at the annular cross-section corresponding to different calculation nodes. ; The cyclic displacement will increase sequentially. As the input condition, the solid-liquid two-phase flow cuttings transport model is iteratively simulated, and the average volume concentration of cuttings in the annular section corresponding to each calculation node is solved in each iteration. and the reference volume concentration of the suspension layer Then, the cuttings transport ratio at each calculation node was further calculated under different cycle displacements. ; The rock cuttings carrying ratio By traversing all calculation nodes throughout the entire well section using this formula, a distribution curve of cuttings transport ratio under different circulation displacements is generated. Using a cuttings transport ratio (CTR) greater than or equal to the wellbore cleanliness threshold as a search criterion, the lowest discharge point satisfying this criterion is identified in the cuttings transport ratio distribution curves under different circulation discharge rates, and this point is determined as the minimum cuttings-carrying discharge rate. .

9. The method for optimizing process parameters of a multifunctional integrated tubular column for long naked-eye segments according to claim 8, characterized in that: In step S4, based on the tubing-wellbore coupling matrix elastic modulus and moment of inertia The critical buckling load corresponding to each computational node of the tubing under different buckling modes in the long naked eye segment was calculated. The calculation formula is: ,in The buckling mode order is... The effective length of the calculation unit; Based on the equivalent cyclic density distribution ECD(z) obtained in step S3, and combined with the physical properties of the tubing assembly, the effective buoyancy linear load of the tubing at each calculation node is calculated. Its calculation formula satisfies In the formula, The linear weight per unit length of the tubing in air. The density of the tubular material; the physical properties of the tubular assembly include the linear weight per unit length of the column in air. and column material density ; Based on equivalent circulation density and wellbore geometry A piecewise friction model is established, and the equations of the model are as follows: ,in The coefficient of friction, For the wellbore support force of a conventional tubing section, This refers to the additional contact normal force generated by the rigidity of the tubing. This is the additional friction function generated by the packer due to its high rigidity and small clearance. The inclination angle at the computational node is extracted from the wellbore geometry matrix. Let be the length of the discrete micro-segment of the tubing at each computation node. The characteristic outer diameter of the packer inserted into the tubing string. The total frictional resistance during the process of running the tubing into the target well; Then, the effective buoyancy line load of each calculation node is... Total frictional resistance during the process of running the tubing into the target well By superimposing the data, the actual axial loads at each calculation node can be obtained. .

10. The method for optimizing process parameters of a multifunctional integrated tubular column for long naked-eye segments according to claim 9, characterized in that: In step S6, the actual eccentric position of the tubing string The calculation process includes: taking the actual axial load of the tubing determined in step S4. Input to the tubing-wellbore coupling matrix In the calculation, the radial flexural displacement of each node is calculated. This allows us to obtain the corrected actual eccentricity position of the tubing. ; Corrected actual string eccentricity positions for each calculation node The rheological parameters are then converted into three-dimensional spatial geometric boundary conditions and corrected using the consistency coefficient obtained in step S2. and flow index-corrected rheological parameters Substitute the cement slurry-isolation fluid-drilling fluid into the three-dimensional multiphase flow displacement model to solve the problem and determine the volume ratio of cement slurry at the annular multiphase flow interface. The process of substituting the cement slurry-separating fluid-drilling fluid into a three-dimensional multiphase flow displacement model and determining the volume percentage of cement slurry at the annular multiphase flow interface includes: The equations for the three-dimensional multiphase flow displacement model of cement slurry-separating fluid-drilling fluid are as follows: , For shear stress, , The radial coordinates of the annular flow channel are: For the depth integral variable, Let be the velocity component of the fluid in the radial direction. This represents the main filling velocity component of the fluid in the axial direction. To calculate the local fluid phase density within the grid, The fluid pressure is used; this model focuses on the influence of density difference, viscosity difference and annular eccentricity on the displacement interface in the high temperature environment of deep wells. To determine the volume percentage of cement slurry at the annular multiphase flow interface, the equation will be used. The obtained flow velocity field Substituting into the multiphase flow volume fraction transport equation based on the VOF method Solve in the middle, where This represents the volume percentage of cement slurry at the annular multiphase flow interface. To replace time; Preset replacement displacement optimal search range While ensuring that the equivalent cyclic density is always less than the corresponding formation fracture pressure Under the premise of obtaining the cement slurry volume ratio change map of the displacement displacement within the preferred displacement displacement search interval, and selecting the cement slurry volume ratio change map with a cement slurry volume ratio greater than or equal to the cement slurry volume ratio threshold from these cement slurry volume ratio change maps, and taking the displacement displacement corresponding to the selected cement slurry volume ratio change map as the cementing displacement displacement. .

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