CN111691831B - Method for preventing female buckle of large-size borehole stabilizer from losing efficacy - Google Patents

Method for preventing female buckle of large-size borehole stabilizer from losing efficacy Download PDF

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CN111691831B
CN111691831B CN202010446174.6A CN202010446174A CN111691831B CN 111691831 B CN111691831 B CN 111691831B CN 202010446174 A CN202010446174 A CN 202010446174A CN 111691831 B CN111691831 B CN 111691831B
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stabilizer
female buckle
dynamic
threaded joint
box
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CN111691831A (en
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陈锋
狄勤丰
刘彪
王文昌
周星
陈功
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University of Shanghai for Science and Technology
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    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
    • E21B17/02—Couplings; joints
    • E21B17/04—Couplings; joints between rod or the like and bit or between rod and rod or the like
    • E21B17/042—Threaded
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
    • E21B17/10—Wear protectors; Centralising devices, e.g. stabilisers
    • E21B17/1078—Stabilisers or centralisers for casing, tubing or drill pipes
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
    • G06F17/10—Complex mathematical operations
    • G06F17/11—Complex mathematical operations for solving equations, e.g. nonlinear equations, general mathematical optimization problems
    • G06F17/12—Simultaneous equations, e.g. systems of linear equations

Abstract

The invention provides a method for preventing failure of a female buckle of a stabilizer of a large-size well, which considers an additional bending effect caused by large difference of the outer diameters of a stabilizer and a drill collar, utilizes dynamic characteristic analysis of a drill column to determine dynamic load of the female buckle end of a drilling tool assembly stabilizer in the large-size well, determines stress distribution characteristics and change rules of the threaded joint at the female buckle end of the stabilizer under the condition of the dynamic load through three-dimensional elastoplastic finite element analysis of the threaded joint at the female buckle end of the stabilizer, and obtains the maximum value of dynamic bending moment (T-shaped maximum value)bmax) And a minimum value (T)bmin) Stress maximum value sigma of 2 nd to 5 th teeth at large end of female buckle of stabilizer under actionbmaxAnd σbminCombined with the frequency of variation f of the dynamic bending momentbAnd determining a failure risk coefficient R of the large-size well stabilizer box, dividing the failure risk into three types of small, medium and large, and reducing the failure risk of the large-size well stabilizer box by optimizing the drilling tool assembly and the drilling tool parameters when the failure risk is medium and large.

Description

Method for preventing female buckle of large-size borehole stabilizer from losing efficacy
Technical Field
The invention relates to the technical field of oil field drilling, in particular to a female buckle failure prevention method for a large-size well stabilizer.
Background
The increasing demand of oil gas resources and the decreasing of shallow layer oil gas resources lead the development of deep water and deep layer oil gas resources to be continuously improved, and the proportion of deep wells and ultra deep wells is more and more increased. In recent years, a batch of ultra-deep wells with well depths of more than 8000.0m appear, such as a northward eagle 1 well (8588.0m), a northward 5-5H well (8520.0m), a northward Sungpeng 1 well (8450.0m) and the like, and make important contributions to drilling of deep oil and gas resources in China. Because the well exceeds 8000.0m in depth and the geological structure and lithology are complex, a multi-layer well body structure is necessary, wherein a well bore with the upper large size of 444.5mm is a main power well section and has the length of about 5000.0 m.
In order to increase the speed, control the inclination and reduce the risk of drilling jamming induced by well wall block falling, a single stabilizer pendulum BHA with a straight screw is often adopted in field construction. However, the fracture accident of the stabilizer box often occurs in the using process, and the large end of the stabilizer box of 3 wells in 7 wells drilled in a certain oil field is fractured, so that great economic loss is caused. At present, no report is found on a female buckle failure prevention method of a large-size borehole stabilizer. The invention provides a method for preventing a large-size borehole stabilizer box from losing efficacy, which is based on BHA dynamic characteristic macroscopic analysis and threaded joint screw local stress analysis, provides a failure risk coefficient R of the large-size borehole stabilizer box, divides the failure risk into three types of small, medium and large, and enables the failure risk to be small by optimizing drilling tool combination and drilling tool parameters when the failure states are medium and large so as to improve the safety of drilling operation.
Disclosure of Invention
The invention aims to provide a method for preventing the female thread of a large-size borehole stabilizer from losing efficacy by aiming at the defects of the prior art, which considers the additional bending effect caused by the large difference between the outer diameters of a stabilizer and a drill collar, evaluates the failure risk of the threaded joint at the female thread end of the stabilizer according to the dynamic load characteristic of a drilling tool assembly in the large-size borehole, reduces the dynamic bending effect near the stabilizer by optimizing BHA structural parameters and drilling parameters, and reduces the failure risk of the female thread of the large-size borehole stabilizer. The method has very important significance for improving the use safety of the female buckle of the large-size borehole stabilizer.
In order to achieve the purpose, the invention adopts the following inventive concept:
large-size well stabilizer female buckle loss prevention deviceThe method comprises the steps of firstly considering an additional bending effect caused by large difference between the outer diameters of a stabilizer and a drill collar, determining the dynamic load characteristics of a drilling tool assembly in a large-size borehole, evaluating the failure risk of a threaded joint at a box end of the stabilizer, and then reducing the dynamic bending effect near the stabilizer and reducing the failure risk of the box of the large-size borehole stabilizer by optimizing BHA structural parameters and drilling parameters. Considering the additional bending effect caused by the large difference between the outer diameters of the stabilizer and the drill collar, determining the dynamic load of the female buckle end of the drilling tool assembly stabilizer in the large-size well by utilizing the drill string dynamic characteristic analysis, determining the stress distribution characteristics and the change rule of the threaded joint at the female buckle end of the stabilizer under the condition of the dynamic load through the three-dimensional elasto-plastic finite element analysis of the threaded joint at the female buckle end of the stabilizer, and obtaining the maximum dynamic bending moment (T)bmax) And a minimum value (T)bmin) Maximum stress value sigma of 2 nd to 5 th teeth at large end of female buckle of stabilizer under actionbmaxAnd σbminCombined with the frequency of variation f of the dynamic bending momentbAnd determining a failure risk coefficient R of the large-size well stabilizer box, dividing the failure risk into three types of small, medium and large, and reducing the failure risk of the large-size well stabilizer box by optimizing the drilling tool assembly and the drilling tool parameters when the failure risk is medium and large.
According to the inventive concept, the invention adopts the following technical scheme:
a female buckle failure prevention method for a large-size borehole stabilizer comprises the following specific steps:
1) determining the actual shaft size, drilling tool combination structure parameters, drilling fluid density, drilling pressure and rotating speed of a large-size well through engineering design or measurement of a special tool, considering additional bending effect caused by large difference of the outer diameters of the stabilizer and the drill collar, and determining the dynamic load characteristics of the female buckle end of the stabilizer based on the dynamic characteristics of the drill string, including the maximum dynamic axial force (F)max) Dynamic torque maximum (T)nmax) Maximum dynamic bending moment (T)bmax) And a minimum value (T)bmin) Dynamic bending moment variation frequency fb(ii) a Determining the screwing torque T of the threaded joint at the female end of the stabilizer according to the industry standardni；
When the dynamic load is determined, the additional bending effect T caused by large difference between the outer diameters of the stabilizer and the drill collarMIs obtained by the following formula:
Figure BDA0002505807020000021
in the formula (I), the compound is shown in the specification,
Figure BDA0002505807020000022
δ＝DS-DCΔ ═ 2(cosh (η) -1) - η sinh (η); r is the radius of curvature of the borehole, m; EI bending stiffness, Nm2(ii) a L is the length of the segment, m; dSIs the stabilizer outer diameter, m; dS0Is the stabilizer body outer diameter, m; fTIs the axial force, N;
2) testing a nominal stress-nominal strain relation curve of a threaded joint material at a female buckle end of a stabilizer by using a material performance testing device, and determining a material yield limit sigma0；
3) Measuring geometric parameters of the threaded joint at the female buckle end of the stabilizer, wherein the geometric parameters comprise the outer diameter, the inner diameter, the thread parameters, female buckle boring holes, male buckle nose end, shoulder parameters and the like of the joint, establishing a three-dimensional geometric model of the threaded joint at the female buckle end of the stabilizer, performing mathematical dispersion on the threaded joint at the female buckle end of the stabilizer by using a partitioning grid division method, and establishing a three-dimensional elastoplasticity finite element model containing the thread helix angle characteristic;
4) on application of make-up torque TniMaximum value of dynamic axial force FmaxAnd dynamic torque maximum TnmaxOn the basis of the dynamic bending moment, the maximum value T of the dynamic bending moment is applied to the threaded joint of the female buckle of the stabilizerbmaxMinimum value TbminDetermining the maximum von Mises stress sigmamax(ii) a Determining the maximum value T of the dynamic bending momentbmaxMinimum value TbminUnder the action of the stress distribution rule of von Mises of the threaded joint at the box end of the stabilizer, and obtaining the stress peak value sigma of von Mises of the 2 nd to 5 th teeth of the box big endbmaxAnd σbmin；
5) Calculating the failure risk coefficient R of the large-size well stabilizer box by using the following formula:
Figure BDA0002505807020000031
in the formula sigmamaxFor maximum von Mises stress, sigma, of a threaded joint of a stabilizer box0Is the yield limit of the material;
6) the safety of the female buckle of the large-size borehole stabilizer is evaluated according to the following rules:
a) when R <5.0, the failure risk is small;
b) when R is more than or equal to 5.0 and less than or equal to 10.0, the failure risk is moderate;
c) when R is more than 10.0, the failure risk is large;
7) aiming at three states of the female buckle of the large-size borehole stabilizer, the following measures are respectively adopted:
a) when R is less than 5.0, the stabilizer box has smaller failure risk, and the drilling can be continued according to the original drilling combination and drilling parameters;
b) when R is more than or equal to 5.0 and less than or equal to 10.0, determining the BHA critical rotating speed based on a modal method, properly adjusting drilling parameters according to the characteristics of the BHA critical rotating speed, and repeating the steps 1) -6) to evaluate the failure risk of the stabilizer box until R is less than 5.0;
c) and when R is larger than 10.0, optimizing drilling tool assembly and drilling parameters, and repeating the steps 1) to 6) to evaluate the failure risk of the stabilizer box until R is smaller than 5.0.
Preferably, the load condition of the threaded joint at the female end of the stabilizer is determined according to the dynamic finite element calculation of the full-well drill string, and the additional bending effect caused by the variable section of the female end of the stabilizer in a large-size well hole is considered.
Preferably, the determination of the von Mises stress is based on three-dimensional mechanical calculation of the threaded joint under the complex load condition.
Preferably, the stabilizer box threaded joint is any one of currently used stabilizer box threaded joints.
Compared with the prior art, the invention has the following prominent substantive characteristics and remarkable technical progress:
the invention provides a method for preventing failure of a large-size well stabilizer box, which considers an additional bending effect caused by large difference of the outer diameters of a large-size well stabilizer and a drill collar, determines a load working condition at the cross section of the stabilizer box end according to drill string dynamics analysis, evaluates failure risk of a threaded joint at the stabilizer box end based on a three-dimensional elastic-plastic finite element analysis method, reduces dynamic bending effect near the stabilizer through BHA structural parameter optimization and drilling parameter optimization, reduces failure risk of the large-size well stabilizer box, and improves use safety of the large-size well stabilizer box.
Drawings
FIG. 1 is a flow chart of a method for evaluating the safety of a large-scale wellbore stabilizer box.
FIG. 2 is a schematic diagram of the additional bending effect produced by the difference in outer diameters of the stabilizer and the drill collar.
Fig. 3 is the dynamic load characteristic at the stabilizer box end section (before optimization).
FIG. 4 is the minimum value of the dynamic bending moment TbminAnd (3) distributing the stress of the threaded joint at the female buckle end of the stabilizer under the action of the stress distribution rule (before optimization).
FIG. 5 is the maximum value of the dynamic bending moment TbmaxAnd (3) distributing the stress of the threaded joint at the female buckle end of the stabilizer under the action of the stress distribution rule (before optimization).
FIG. 6 shows the bending moment from the minimum value TbminUp to a maximum value TbmaxStress change conditions of each key part of the threaded joint at the female buckle end of the stabilizer are obtained (before optimization) in the process.
Fig. 7 is the dynamic load characteristic at the stabilizer box end section (after optimization).
FIG. 8 is the minimum value of dynamic bending moment TbminAnd (3) under the action, the stress distribution rule of the threaded joint at the female buckle end of the stabilizer is optimized.
FIG. 9 is the maximum value of dynamic bending moment TbmaxAnd (3) under the action, the stress distribution rule of the threaded joint at the female buckle end of the stabilizer is optimized.
FIG. 10 shows the bending moment from the minimum value TbminTo a maximum value TbmaxStress change conditions (after optimization) of each key part of the threaded joint at the female buckle end of the stabilizer in the process.
Detailed Description
A method for preventing failure of a female buckle of a large-size well stabilizer comprises the steps of considering an additional bending effect caused by large difference between the outer diameters of a stabilizer and a drill collar in a large-size well, evaluating safety of the female buckle of the large-size well stabilizer according to dynamic characteristics of a drill column and three-dimensional mechanical characteristics of a threaded joint at the female buckle end of the stabilizer, reducing a dynamic bending effect near the stabilizer through optimization of BHA structural parameters and optimization of drilling parameters, and reducing failure risks of the female buckle of the large-size well stabilizer.
The invention will be further described with reference to the accompanying drawings and preferred embodiments.
The first embodiment is as follows:
referring to fig. 1 to 10, a method for preventing a large-sized wellbore stabilizer box from failing comprises the following steps:
1) determining the actual shaft size of a large-size well, the structural parameters of a drilling tool assembly, the density of drilling fluid, the bit pressure and the rotating speed through engineering design or measurement, considering the additional bending effect caused by the large difference between the outer diameters of the stabilizer and the drill collar, and determining the dynamic load characteristics of the female buckle end of the stabilizer based on the dynamic characteristics of the drill string, including the maximum value F of the dynamic axial forcemaxDynamic torque maximum TnmaxMaximum value of dynamic bending moment TbmaxAnd a minimum value TbminDynamic bending moment variation frequency fb(ii) a Determining the screwing torque T of the threaded joint at the female end of the stabilizer according to the industry standardni；
When the dynamic load is determined, the additional bending effect T caused by large difference between the outer diameters of the stabilizer and the drill collarMIs obtained by the following formula:
Figure BDA0002505807020000041
in the formula (I), the compound is shown in the specification,
Figure BDA0002505807020000042
δ＝DS-DCΔ ═ 2(cosh (η) -1) - η sinh (η); r is the radius of curvature of the borehole, m; EI bending stiffness, Nm2(ii) a L is the length of the segment, m; dSIs the stabilizer outer diameter, m; dS0M is the stabilizer body outer diameter; fTIs the axial force, N;
2) testing a nominal stress-nominal strain relation curve of a threaded joint material at a female buckle end of a stabilizer by using a material performance testing device, and determining a material yield limit sigma0；
3) Measuring geometric parameters of the threaded joint at the female buckle end of the stabilizer, wherein the geometric parameters comprise the outer diameter, the inner diameter and the thread tooth parameters of the joint, female buckle boring holes, male buckle nose ends and shoulder parameters, establishing a three-dimensional geometric model of the threaded joint at the female buckle end of the stabilizer, performing mathematical dispersion on the threaded joint at the female buckle end of the stabilizer by using a partitioning grid division method, and establishing a three-dimensional elastoplasticity finite element model containing the thread helix angle characteristic;
4) on application of make-up torque TniMaximum value of dynamic axial force FmaxAnd dynamic torque maximum TnmaxOn the basis of the dynamic bending moment, the maximum value T of the dynamic bending moment is applied to the threaded joint of the female buckle of the stabilizerbmaxMinimum value TbminDetermining the maximum von Mises stress sigmamax(ii) a Determining the maximum value T of the dynamic bending momentbmaxMinimum value TbminUnder the action of the stress distribution rule of von Mises of the threaded joint at the box end of the stabilizer, and obtaining the stress peak value sigma of von Mises of the 2 nd to 5 th teeth of the box big endbmaxAnd σbmin；
5) Calculating the failure risk coefficient R of the large-size well stabilizer box by using the following formula:
Figure BDA0002505807020000051
in the formula sigmamaxFor maximum von Mises stress, sigma, of threaded joint of box and box of stabilizer0Is the yield limit of the material;
6) the safety of the female buckle of the large-size borehole stabilizer is evaluated according to the following rules:
a) when R <5.0, the risk of failure is small;
b) when R is more than or equal to 5.0 and less than or equal to 10.0, the failure risk is moderate;
c) when R is more than 10.0, the failure risk is large;
7) aiming at three states of the female buckle of the large-size borehole stabilizer, the following measures are adopted respectively:
a) when R is less than 5.0, the stabilizer box has smaller failure risk, and the drilling can be continued according to the original drilling combination and drilling parameters;
b) when R is more than or equal to 5.0 and less than or equal to 10.0, determining the BHA critical rotating speed based on a modal method, properly adjusting drilling parameters according to the characteristics of the BHA critical rotating speed, and repeating the steps 1) -6) to evaluate the failure risk of the stabilizer box until R is less than 5.0;
c) and when R is larger than 10.0, optimizing drilling tool assembly and drilling parameters, and repeating the steps 1) to 6) to evaluate the failure risk of the stabilizer box until R is smaller than 5.0.
According to the method for preventing the failure of the female buckle of the large-size borehole stabilizer, the additional bending effect caused by the large difference between the outer diameters of the stabilizer and the drill collar is considered, the failure risk of the threaded joint at the female buckle end of the stabilizer is evaluated according to the dynamic load characteristics of the drilling tool assembly in the large-size borehole, the dynamic bending effect near the stabilizer is reduced through the optimization of BHA structural parameters and the optimization of drilling parameters, and the failure risk of the female buckle of the large-size borehole stabilizer is reduced. The method has very important significance for improving the use safety of the female buckle of the large-size borehole stabilizer.
Example two:
this embodiment is substantially the same as the first embodiment, and is characterized in that:
the load working condition of the threaded joint at the female buckle end of the stabilizer is determined by finite element calculation of the whole well drill string dynamics, and an additional bending effect caused by variable cross sections of the female buckle end of the stabilizer in a large-size well bore is considered; determining the stress of the von Mises based on three-dimensional mechanical calculation of the threaded joint under the complex load condition; the stabilizer box threaded joint is any one of currently used stabilizer box threaded joints.
Example three:
taking the example of drilling a large-sized well, the well is a vertical exploration well in a certain oil field, and the 444.5mm well is 4218.0m in length. Drilling tool assembly actually used for this well (with monostable):
a phi 444.5mm PDC drill bit multiplied by a 0.5m + phi 286.0mm (76.2mm) straight screw multiplied by a 9.6m + phi 279.4mm (76.2mm) drill collar multiplied by a 9.2m + phi 441.0mm (76.2mm) centralizer multiplied by a 2.3m + phi 241.3mm (76.2mm) drill collar multiplied by a 47.0m + phi 203.2mm (71.4mm) drill collar multiplied by a 56.6m + phi 139.7mm (92.1mm) weighted drill rod multiplied by a 72.4m + phi 139.7mm drill rod multiplied by a 121.4mm drill rod multiplied by …. The numbers in parentheses are the inside diameters.
Based on Lagrange's equation, a drill string dynamics finite element model can be established
Figure BDA0002505807020000061
In the formula (I), the compound is shown in the specification,
Figure BDA0002505807020000062
u is acceleration, speed and displacement matrix on the node of the drill column respectively. M is the mass matrix of the drill string, and considering the inertia mass generated by the movement of the drill string, the mass matrix can be divided into two parts: m is M1+M2。M1Is a translational inertial mass in three orthogonal directions, M2An inertial mass rotating about three orthogonal axes. K is a stiffness matrix comprising linear stiffness KLAnd a non-linear stiffness KNWherein the nonlinear stiffness matrix exhibits axial and lateral, axial and torsional, and lateral and torsional coupling. And C is a damping matrix. F is an external force matrix that primarily contains gravity and the imbalance forces generated when the eccentric drill string is rotated. According to actual parameters on site, the drilling fluid density in a drill string dynamics finite element model is 1.19g/cm3The bit weight is 60.0kN, and the rotating speed is 60.0 r/min.
Considering that in a large-sized borehole, the outer diameter of the stabilizer bar is greatly different from that of the drill collar, especially in a bending well section or a well section with a large change rate of the borehole total angle, when the BHA is in tension or in compression, the change of the initial bending moment is caused by the change of the section, and an additional bending effect exists, as shown in FIG. 2. This additional bending effect is more severe and has a dynamically changing character if the dynamic impact effect caused by the inevitable drill string rubbing against the borehole wall is taken into account.
Substituting the formula (1) into a dynamic finite element equation (3) of the BHA, and solving the BHA dynamic finite element model by using a node iteration method and a Newmark method to obtain a stabilizer matrixDynamic bending moment, torque and axial force at the buckle end, see figure 3. According to FIG. 3, the maximum value F of the dynamic axial force is takenmax-40.0kN (compression), dynamic torque maximum Tnmax15.0kN m, maximum value of dynamic bending moment Tbmax453.0kN m and a minimum value Tbmin0kN m, dynamic bending moment variation frequency fbAnd 22.0Hz is used as the extreme load working condition of the threaded joint at the female buckle end of the stabilizer. For the stabilizer box threaded joint, the torque T of the box threaded joint can be known by inquiring API standardni＝142.5kN·m。
A three-dimensional elastoplasticity finite element model of the threaded joint at the female buckle end of the stabilizer is established, the use safety of the threaded joint is evaluated by using the method, and the main parameters of the threaded joint are shown in Table 1.
TABLE 1 drill pipe joint Main parameters
Joint outside diameter/mm 241.0
Joint internal diameter/mm 76.0
Thread profile 75/8″REG
The material used for the threaded joint at the female buckle end of the stabilizer is 37CrMnMoA, which is an isotropic elastoplastic material with the elastic modulus of 2.06 multiplied by 105MPa, Poisson's ratio of 0.29, material yield limit sigma0827.4 MPa. The true stress-plastic strain relationship of the material is shown in table 2.
TABLE 2 true stress-plastic strain relationship for materials
True stress/MPa Plastic strain True stress/MPa Plastic strain True stress/MPa Plastic strain
827.4 0 907.1 0.00251 1035.4 0.04007
845.2 0.0001 927.3 0.00519 1061.5 0.05041
855.3 0.00023 944.6 0.01033 1082.9 0.06065
861.4 0.00032 961.0 0.01523 1099.8 0.07082
875.6 0.00069 976.5 0.02008 1110.5 0.08001
888.1 0.00119 1009.3 0.03059 1117.2 0.09095
And applying a screwing torque (142.5 kN.m), an axial force (-40.0kN), a working torque (15.0 kN.m) and a bending moment (453.0 kN.m) to the threaded joint at the female screwing end of the stabilizer in sequence to obtain the stress distribution characteristic of the threaded joint under the complex load condition. Minimum value of dynamic bending moment TbminAnd maximum value of dynamic bending moment TbmaxThe stress distribution law of the von Mises of the threaded joint of the stabilizer under the action is respectively shown in fig. 4 and fig. 5.
The bending moment is taken out from the minimum value TbminUp to a maximum value TbmaxThe stress change of each key part of the threaded joint of the stabilizer in the process is shown in fig. 6. The maximum von Mises stress of the threaded joint of the female buckle of the stabilizer is positioned at the thread teeth at the large end of the male buckle of the drill collar and has the value of sigmamax973.1MPa, but the stress change at the thread tooth of the large end of the drill collar pin is small under the action of bending moment, the stress peak value is 951.5-973.1 MPa, and the change amplitude isThe degree is only 21.6 MPa. The stress variation at the 2 nd to 5 th teeth of the big end of the female buckle of the stabilizer is large, and the minimum value T of the bending momentbminAnd maximum value TbmaxUnder the action, the von Mises stress peak values of the 2 nd to 5 th teeth at the big end of the female button are respectively sigmabmin334.1MPa and sigmabmax799.1MPa, the variation amplitude is up to 465.0MPa, and the variation frequency fb＝22.0Hz。
The above results can be obtained by substituting the above results into the following formula (2):
Figure BDA0002505807020000071
it can be seen that in the large-sized well bore, the risk of stabilizer box failure is greater under the BHA structural parameters and drilling parameters. In fact, when the well is drilled to the well depth of 3057.91m, the stabilizer box is broken, and the broken position is located at the 3 rd to 4 th teeth of the internal thread of the box, which is consistent with the conclusion obtained by the method.
The BHA structural parameters were optimized to yield the following drill tool assembly (with bi-stabilizers):
phi 444.5mm PDC multiplied by 0.5m + phi 286mm (76.2mm) screw multiplied by 9.6m + phi 279.4mm (76.2mm) drill collar multiplied by 18.4m + phi 441.0mm (76.2mm) centralizer + phi 279.4mm (76.2mm) drill collar multiplied by 9.2m + phi 442.0mm (76.2mm) centralizer + phi 228.6mm (71.4mm) drill collar multiplied by 28.5m + phi 203.2mm (71.4mm) nonmagnetic drill collar multiplied by 9.2m + phi 203.2mm (71.4mm) drill collar multiplied by 57.0m + phi 139.7mm (92.1mm) weighted drill rod multiplied by 84.0m + phi 139.7mm drill rod (121.4mm) multiplied by ….
According to the actual parameters on site, the density of the drilling fluid is 1.19g/cm3. According to the characteristic of the critical rotating speed of the BHA, drilling parameters which easily cause drill string resonance are avoided, the drilling pressure is 90.0kN, and the rotating speed is 65.0 r/min.
The dynamic bending moment, torque, and axial force of the stabilizer box end were determined based on BHA dynamics, see fig. 7. According to FIG. 7, the maximum value F of the dynamic axial force is takenmax-51.0kN (compression), dynamic torque maximum Tnmax14.3kN m, maximum value of dynamic bending moment Tbmax28.9kN m and a minimum value Tbmin0kN m, dynamic bending moment variation frequency fb2.4Hz as extreme load of a stabilizer box end threaded jointAnd (5) working conditions.
And applying a fastening torque (142.5 kN.m), an axial force (-51.0kN), a working torque (14.3 kN.m) and a bending moment (28.9 kN.m) to the threaded joint at the female fastening end of the stabilizer in sequence to obtain the stress distribution characteristic of the threaded joint under the complex load condition. Minimum value of dynamic bending moment TbminAnd maximum value of dynamic bending moment TbmaxThe stress distribution laws of the von Mises of the threaded joint of the stabilizer under the action are respectively shown in fig. 8 and fig. 9.
The bending moment is controlled by the minimum value TbminUp to a maximum value TbmaxThe stress change of each key part of the stabilizer threaded joint in the process is shown in fig. 10. It can be seen that the maximum von MISES stress of the threaded joint of the box of the stabilizer is positioned at the thread teeth at the large end of the pin of the drill collar, and the value is sigmamax942.8MPa, the stress peak value fluctuates between 935.4 MPa and 942.8MPa under the action of the dynamic bending moment, and the change amplitude is only 7.4 MPa. The stress fluctuation at teeth 2 to 5 at the large end of the upper stabilizer female buckle is relatively large, and the minimum value T of the bending moment isbminAnd maximum value TbmaxUnder the action, the stress peak values of von Mises of teeth 2 to 5 at the big end of the female buckle are respectively sigmabmin328.4MPa and σbmax396.6MPa, with a variation of 68.2 MPa.
The above results were substituted for formula (2) to obtain:
Figure BDA0002505807020000081
therefore, through optimization of BHA structural parameters and optimization of drilling parameters, the dynamic bending effect near the stabilizer is greatly reduced, and the failure risk of the female buckle of the large-size borehole stabilizer is reduced.
According to the method for preventing the failure of the female buckle of the large-size well stabilizer, the additional bending effect caused by the large difference between the outer diameters of the stabilizer and the drill collar is considered, the dynamic load of the female buckle end of the drilling tool assembly stabilizer in the large-size well is determined by utilizing the dynamic characteristic analysis of the drill column, the stress distribution characteristics and the change rule of the threaded joint of the female buckle end of the stabilizer under the condition of the dynamic load are determined by utilizing the three-dimensional elastic-plastic finite element analysis of the threaded joint of the female buckle end of the stabilizer, and the maximum dynamic bending moment is obtainedValue (T)bmax) And a minimum value (T)bmin) Maximum stress value sigma of 2 nd to 5 th teeth at large end of female buckle of stabilizer under actionbmaxAnd σbminCombined with the frequency of variation f of the dynamic bending momentbAnd determining a failure risk coefficient R of the large-size well stabilizer box, dividing the failure risk into three types of small, medium and large, and reducing the failure risk of the large-size well stabilizer box by optimizing the drilling tool assembly and the drilling tool parameters when the failure risk is medium and large. According to the embodiment, the dynamic bending effect near the stabilizer is reduced through the optimization of the BHA structural parameters and the optimization of the drilling parameters, the failure risk of the large-size borehole stabilizer box is reduced, and the use safety of the large-size borehole stabilizer box is improved.
The embodiments of the present invention have been described with reference to the accompanying drawings, but the present invention is not limited to the embodiments, and various changes and modifications can be made according to the purpose of the invention, and any changes, modifications, substitutions, combinations or simplifications made according to the spirit and principle of the technical solution of the present invention shall be equivalent substitutions, as long as the purpose of the present invention is met, and the technical principle and the inventive concept of the method for preventing the female snap of the large-sized well stabilizer from failing shall fall within the protection scope of the present invention.

Claims (4)

1. A female buckle failure prevention method for a large-size borehole stabilizer is characterized by comprising the following specific steps:
1) determining the actual shaft size of a large-size well, the structural parameters of a drilling tool assembly, the density of drilling fluid, the bit pressure and the rotating speed through engineering design or measurement, considering the additional bending effect caused by the large difference between the outer diameters of the stabilizer and the drill collar, and determining the dynamic load characteristics of the female buckle end of the stabilizer based on the dynamic characteristics of the drill string, including the maximum value F of the dynamic axial forcemaxDynamic torque maximum TnmaxMaximum value of dynamic bending moment TbmaxAnd a minimum value TbminDynamic bending moment variation frequency fb(ii) a Determining the screwing torque T of the threaded joint at the female end of the stabilizer according to the industry standardni；
In determining the stabilizer barAdditional bending effect T caused by large difference between the outer diameters of the stabilizer and the drill collar during dynamic load characteristic of the buckle endMIs obtained by the following formula:
Figure FDA0003335286220000011
in the formula (I), the compound is shown in the specification,
Figure FDA0003335286220000012
δ＝DS-DCΔ ═ 2(cosh (η) -1) - η sinh (η); r is the radius of curvature of the borehole, m; EI bending stiffness, Nm2(ii) a L is the length of the segment, m; dSIs the stabilizer outer diameter, m; dCIs the stabilizer body outer diameter, m; fTIs the axial force, N;
2) testing a nominal stress-nominal strain relation curve of a threaded joint material at a female buckle end of a stabilizer by using a material performance testing device, and determining a material yield limit sigma0；
3) Measuring geometric parameters of the threaded joint at the female buckle end of the stabilizer, wherein the geometric parameters comprise the outer diameter, the inner diameter and the thread tooth parameters of the joint, female buckle boring holes, male buckle nose ends and shoulder parameters, establishing a three-dimensional geometric model of the threaded joint at the female buckle end of the stabilizer, performing mathematical dispersion on the threaded joint at the female buckle end of the stabilizer by using a partitioning grid division method, and establishing a three-dimensional elastoplasticity finite element model containing the thread helix angle characteristic;
4) on application of make-up torque TniMaximum value of dynamic axial force FmaxAnd dynamic torque maximum TnmaxOn the basis of the dynamic bending moment, the maximum value T of the dynamic bending moment is applied to the threaded joint of the female buckle of the stabilizerbmaxMinimum value TbminDetermining the maximum von Mises stress sigmamax(ii) a Determining the maximum value T of the dynamic bending momentbmaxMinimum value TbminThe stress distribution rule of von Mises of the threaded joint at the box end of the stabilizer under the action is obtained, and the peak value sigma of the stress of von Mises of teeth 2-5 at the big end of the box is obtainedbmaxAnd σbmin；
5) Calculating the failure risk coefficient R of the female buckle of the large-size borehole stabilizer by using the following formula:
Figure FDA0003335286220000013
in the formula sigmamaxFor maximum von Mises stress, sigma, of a threaded joint of a stabilizer box0Is the yield limit of the material;
6) the safety of the female buckle of the large-size borehole stabilizer is evaluated according to the following rules:
a) when R <5.0, the failure risk is small;
b) when R is more than or equal to 5.0 and less than or equal to 10.0, the failure risk is moderate;
c) when R is more than 10.0, the failure risk is large;
7) aiming at three states of the female buckle of the large-size borehole stabilizer, the following measures are respectively adopted:
a) when R is less than 5.0, the stabilizer box has smaller failure risk, and the drilling can be continued according to the original drilling combination and drilling parameters;
b) when R is larger than or equal to 5.0 and smaller than or equal to 10.0, determining BHA critical rotation speed based on a modal method, properly adjusting drilling parameters according to BHA critical rotation speed characteristics, and repeating the steps 1) -6) to evaluate the failure risk of the female buckle of the stabilizer until R is smaller than 5.0;
c) and when R is larger than 10.0, optimizing drilling tool assembly and drilling parameters, and repeating the steps 1) to 6) to evaluate the failure risk of the stabilizer box until R is smaller than 5.0.
2. The method of claim 1, wherein the stabilizer box end nipple dynamic load characteristic is determined from a full well drill string dynamics finite element calculation and takes into account additional bending effects caused by stabilizer box end cross-section in large size wellbores.
3. The method of claim 1, wherein the von Mises stress is determined based on three-dimensional mechanical calculations of the threaded joint under complex loading conditions.
4. The method of claim 1, wherein the stabilizer box thread is any one of currently used stabilizer box threads.
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