CN117521435A - Quantitative safety evaluation method for liner hanger - Google Patents
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Abstract
The invention provides a quantitative safety evaluation method for a liner hanger, and belongs to the technical field of high-temperature high-pressure deep well production. The method comprises the steps of establishing a finite element mechanical entity model of the position of the liner hanger, and converting the finite element mechanical entity model of the position of the liner hanger into a finite element mechanical grid model; performing finite element simulation on the pressure gradient of the outer wall of the tail pipe hanger and the tieback cylinder; establishing a prediction model of the pressure gradient of the outer wall of the pipe column along with the change of the internal pressure; establishing a triaxial stress checking model of the technical sleeve; and safety evaluation is carried out on the tail pipe hanger by adopting a prediction model of the pressure gradient of the outer wall of the pipe column along with the change of the internal pressure and a triaxial stress check model of the technical sleeve. The invention realizes timely and quantitatively evaluating the safety of the tail pipe hanger according to the ground stress and the pressure in the shaft in a breakthrough manner, and has guiding significance for actual production.
Description
Technical Field
The invention relates to the technical field of high-temperature high-pressure deep well production, in particular to a quantitative safety evaluation method for a liner hanger.
Background
When well region is operated, well depth has a great influence on operation requirements, and a liner suspension well cementation process is generally adopted in deep well operation. The liner cementing is realized through the liner hanger, the weight of the sleeve of the deep well for one-time well descending is reduced, the load of a drilling machine lifting system during the sleeve descending is improved, the flowing resistance of the injected cement paste is reduced, and the safe construction is facilitated. The problem that drilling operation is affected due to abrasion of an upper casing can be solved through tail pipe tie-back; the liner suspension well cementation technology is used, so that the sleeve consumption can be reduced, and the drilling cost can be saved. Meanwhile, for well region operation with ultrahigh formation pressure (up to 153 MPa) and high shut-in pressure (up to 118 MPa), according to the requirements of high-temperature high-pressure well integrity design, guidelines and management specifications, when operations such as oil testing, fracturing transformation and the like are carried out, the liner hanger is used as one of key parts of a well barrier, and has important influence on oil testing, fracturing transformation and well control safety.
The liner hanger is used in the actual well conditions of the actual deep well and the ultra-deep high temperature well, especially after the ultra-deep liner hanger is well cemented under complex conditions, the actual outer wall pressure problem of the hydraulic cylinder and the safety analysis and evaluation thereof are vital to the safe production. However, at present, a field engineer or a liner hanger designer can only estimate the pressure of the outer wall of the hanger after well cementation by experience, for example, the pressure is directly transmitted to the outer wall of a hydraulic cylinder according to the stratum pressure, or the external pressure is directly calculated according to the pressure of a brine density liquid column, so that the pressure calculation is inaccurate, and the safety is difficult to ensure. At present, no borrowable liner hanger safety evaluation method exists, and related researches are required to be developed in a targeted manner.
The safety of the liner hanger can be improved to a certain extent by improving the self structure of the liner hanger, but the improved liner hanger lacks verification of practical application, and further lacks accurate evaluation of the safety of the liner hanger, so that unsafe states of the liner hanger cannot be predicted and found in time.
The prior art has the following defects:
1. technicians lack a liner hanger safety evaluation method through experience estimation;
2. The problem of lack of liner hanger safety evaluation cannot be avoided by improving the liner hanger self structure, and unsafe conditions of the liner hanger cannot be predicted and found in time.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a quantitative safety evaluation method for a liner hanger, which comprises the following steps: establishing a finite element mechanical solid model of the position of the liner hanger, wherein the finite element mechanical solid model sequentially comprises a profile stratum, a cement sheath, a technical sleeve, liquid, a liquid cylinder and a central pipe from the profile of the liner hanger inwards; the technical sleeve comprises: the hydraulic cylinder is positioned in the middle, the tieback cylinder is externally connected with the upper part of the hydraulic cylinder, and the tail pipe is externally connected with the lower part of the hydraulic cylinder; converting the finite element mechanical entity model of the position of the liner hanger into a finite element mechanical grid model; performing finite element simulation on the pressure gradient of the outer wall of the tail pipe hanger and the tieback cylinder; establishing a prediction model of the pressure gradient of the outer wall of the pipe column along with the change of the internal pressure; establishing a triaxial stress checking model of the technical sleeve; and safety evaluation is carried out on the tail pipe hanger by adopting a prediction model of the pressure gradient of the outer wall of the pipe column along with the change of the internal pressure and a triaxial stress check model of the technical sleeve. The invention realizes timely and quantitatively evaluating the safety of the tail pipe hanger according to the ground stress and the pressure in the shaft in a breakthrough manner, and has guiding significance for actual production.
The invention provides a quantitative safety evaluation method of a liner hanger, which comprises the following steps:
establishing a finite element mechanical solid model of the position of the liner hanger, wherein the finite element mechanical solid model sequentially comprises a profile stratum, a cement sheath, a technical sleeve, liquid, a liquid cylinder and a central pipe from the profile of the liner hanger inwards; the technical sleeve comprises: the hydraulic cylinder is positioned in the middle, the tieback cylinder is externally connected with the upper part of the hydraulic cylinder, and the tail pipe is externally connected with the lower part of the hydraulic cylinder;
converting the finite element mechanical entity model of the position of the liner hanger into a finite element mechanical grid model;
in a finite element mechanical grid model, carrying out finite element simulation on the pressure gradient of the outer wall of the tail pipe hanger and the tieback cylinder of the tail pipe hanger;
establishing a prediction model of the pressure gradient of the outer wall of the pipe column in the finite element mechanical grid model along with the change of the internal pressure;
establishing a triaxial stress checking model of the technical sleeve;
and safety evaluation is carried out on the tail pipe hanger by adopting a prediction model of the pressure gradient of the outer wall of the pipe column along with the change of the internal pressure and a triaxial stress check model of the technical sleeve.
Preferably, the finite element simulation of the pressure gradient of the outer wall of the liner hanger and the tieback tube thereof specifically comprises: and (3) establishing a finite element simulation calculation model of the external ground stress of the hydraulic cylinder or the tieback cylinder by adopting plane strain, and applying the maximum ground stress and the minimum ground stress of the stratum to the finite element simulation calculation model of the external ground stress of the hydraulic cylinder or the tieback cylinder.
Preferably, the finite element simulation of the pressure gradient of the liner hanger and the outer wall of the tieback thereof further comprises: and establishing a finite element simulation calculation model of the external ground stress of the tail pipe by adopting plane strain, wherein the maximum ground stress and the minimum ground stress of the stratum are applied to the finite element simulation calculation model of the external ground stress of the tail pipe.
Preferably, the finite element simulation of the pressure gradient of the liner hanger and the outer wall of the tieback thereof further comprises: and calculating and storing pressure distribution of each contact interface, and dividing the pressure on the contact surface of the outer wall of the innermost hydraulic cylinder or the tieback cylinder by the well depth to obtain pressure gradient data.
Preferably, based on the established finite element mechanical grid model, the ground stress and rock mechanical parameters, stratum rock, cement sheath and technical casing mechanical parameters are combined, and the ground stress and the wellbore internal pressure of the position are calculated to obtain pressure distribution of each contact interface.
Preferably, a prediction model of the pressure gradient of the outer wall of the pipe column along with the change of the internal pressure is established, and the method specifically comprises the following steps:
obtaining the ground stress of the position of the hanger and the internal pressure P of the shaft and the hydraulic cylinder according to the position of the tail pipe hanger, the stratum pressure, the maximum horizontal ground stress gradient, the minimum horizontal ground stress gradient, the pressure of fracturing fluid in the pipe under the limiting working condition and the back pressure of the oil pipe required by the fracturing rupture disc i ；
Applying internal pressure P to well bore and cylinder in grid model of finite element mechanical entity model i And formation pressure P out ，P out Taking the maximum horizontal ground stress;
the suspension weight T of the tail pipe in the cement slurry is calculated according to the following formula:
T＝(ρ s -ρ m )A s L
wherein,
ρ s is the density of steel;
ρ m is the density of the well cementation slurry;
A s is the cross-sectional area of the tail pipe;
l is the length of the tail pipe;
applying a corresponding pretension force on the central tube, the pretension force being determined according to the suspension weight;
continuously changing pressure P in shaft i Obtaining corresponding contact pressure on each path;
and obtaining the change relation of the outer wall pressure of the hydraulic cylinder along with the internal pressure and the change relation of the outer wall pressure of the central tube along with the internal pressure under different working condition environments.
Preferably, after obtaining the relationship of the pressure of the outer wall of the hydraulic cylinder along with the internal pressure change and the relationship of the pressure of the outer wall of the central tube along with the internal pressure change under different working conditions, the method further comprises the following steps:
the external pressure along with the internal pressure on the link path with the thinnest wall thickness of the hydraulic cylinder is averaged to be used as the external wall pressure of the hydraulic cylinder, and the internal pressure of the shaft and the external wall pressure P of the hydraulic cylinder are obtained o The relation between them is as follows:
P o ＝0.618Pi+30.5
obtaining the internal pressure P of the shaft i Pressure P with the outer wall of the central tube oc The relation between them is as follows:
P oc ＝0.322Pi+43.6
in the calculation process, judging whether the cement sheath and the profile stratum rock fail or not by adopting a Drucker-Prager failure criterion, wherein the expression is as follows:
In the method, in the process of the invention,
alpha and k are material parameters;
f is the infinitesimal strength of the profile stratum rock and MPa;
I 1 ＝σ 1 +σ 2 +σ 3
in the method, in the process of the invention,
is the friction angle of the material;
c is cohesion of the material;
σ 1 、σ 2 、σ 3 the maximum principal stress, the intermediate principal stress and the minimum principal stress are respectively;
I 1 is the first invariant of stress;
J 2 is the second invariant of stress deflection.
Preferably, the establishing a triaxial stress checking model of the technical sleeve specifically includes:
the triaxial includes: z axis, r axis and circumference; the Z axis is downwards along the center of the shaft, the r axis is outwards along the radial direction of the shaft, and the circumferential direction is theta;
according to Lame formula of tube column in elastic mechanics theory, establishing axial stress sigma of technical sleeve z Radial stress sigma r And circumferential stress sigma θ The calculation model is as follows:
wherein,
P o is the external extrusion force (MPa) of the technical sleeve;
P i internal pressure (MPa) of the technical sleeve;
r o is the outer radius (mm) of the technical sleeve;
r i is the inner radius (mm) of the technical sleeve;
r is any radius (mm) of the technical sleeve;
δ θ circumferential stress (MPa) at any radius r for a technical sleeve;
δ Z axial stress (MPa) at any radius r for a technical sleeve;
δ r radial stress (MPa) at any radius r for a technical bushing;
F a is the axial load (N).
Preferably, the safety evaluation of the liner hanger by adopting a prediction model of the pressure gradient of the outer wall of the tubular column along with the change of the internal pressure and a triaxial stress check model of the technical sleeve specifically comprises the following steps:
Calculating the outer wall pressure of the hydraulic cylinder and the outer wall pressure of the central tube according to a prediction model of the outer wall pressure gradient of the tubular column along with the change of the internal pressure;
according to the calculated outer wall pressure of the hydraulic cylinder and the outer wall pressure of the central tube, adopting the axial stress sigma of the sleeve at any radius r z Radial stress sigma r And circumferential stress sigma θ Calculating the triaxial stress of the technical sleeve by using the calculation model;
and carrying out safety evaluation on the liner hanger according to the triaxial stress and the triaxial stress safety coefficient.
Preferably, the safety evaluation of the liner hanger by adopting a prediction model of the pressure gradient of the outer wall of the tubular column along with the change of the internal pressure and a triaxial stress check model of the technical sleeve specifically comprises the following steps:
according to the internal pressure of the shaft and the external wall pressure P of the hydraulic cylinder o The relation between the two is used for calculating the outer wall pressure P of the hydraulic cylinder when the internal pressure Pi of any given shaft is calculated o ；
According to the internal pressure P of the shaft i Pressure P with the outer wall of the central tube oc The relation between the two is used for calculating the outer wall pressure P of the central pipe when the internal pressure Pi of the well bore is given oc ；
Using technical sleeve axial stress sigma z Radial stress sigma r And circumferential stress sigma θ Calculating radial stress, circumferential stress and axial stress of the technical sleeve by using the calculation model;
judging whether the triaxial stress of the technical sleeve meets the following safety coefficient S of the triaxial stress according to the fourth strength theory Von-Mises yield strength criterion type 3 And (2) not less than 1.25, if all the conditions are met, the liner hanger is in a safe state, otherwise, the liner hanger is in a dangerous state:
in the method, in the process of the invention,
σ VME triaxial stress (MPa) for technical bushings;
Y p tubing yield strength (MPa) for technical casing;
S 3 is the safety factor of triaxial stress.
Preferably, the converting the finite element mechanical entity model of the position of the liner hanger into the finite element mechanical grid model specifically includes:
the finite element mechanical entity model adopts 8-node unit division structural grids, contact finite units are adopted among different material interfaces, and 5 groups of contact pair unit models are established.
Compared with the prior art, the invention has the following beneficial effects:
(1) The invention adopts the finite element theory of the elastoplastic contact problem and the nonlinear contact problem principle and method of the discontinuous medium thereof, establishes a finite element mechanical entity model of the position of the ultra-deep high-temperature high-pressure well tail pipe hanger, establishes a general prediction model of the pressure gradient of the outer wall of the pipe column along with the change of the internal pressure on the basis, and realizes the timely quantitative evaluation of the safety problem of the hanger according to the ground stress and the pressure in a shaft.
(2) According to the invention, through finite element simulation of the pressure gradient of the outer wall of the liner hanger and the tieback tube thereof, a general prediction model of the pressure gradient of the outer wall of the tubular column along with the change of the internal pressure is established, a set of calculation formulas breaking through the technical bottleneck is formed, triaxial stress checking and safety evaluation are conveniently carried out on a hydraulic cylinder of the hanger, the tieback tube and the liner tube, the formulation of wellhead limiting pressure is also conveniently carried out, and a reliable guiding method is provided for standard evaluation of the ultra-deep well liner hanger.
Drawings
FIG. 1 is a flow chart of a liner hanger quantitative safety evaluation method in accordance with one embodiment of the present invention;
FIG. 2 is a flow chart of a method of quantitatively evaluating the safety of a liner hanger according to yet another embodiment of the present invention;
FIG. 3 is a cross-sectional finite element mechanical solid model of the position of a liner hanger constructed in accordance with one embodiment of the present invention; sigma in the figure m Is ground stress;
FIGS. 4 (a) and (b) are schematic illustrations of a physical model of a downhole hydraulic cylinder and a tieback cylinder, respectively, constructed in accordance with one embodiment of the present invention; p in the figure in Is internal pressure, P out Is the formation pressure;
FIG. 5 is a schematic illustration of a liner hanger wellbore configuration in accordance with one embodiment of the invention;
FIG. 6 is a 1/4 structural schematic diagram of a finite element mechanical mock-up of the position of a liner hanger (the liner hanger being a double pipe string) according to one embodiment of the present invention; in the figure, sigma H Is the maximum ground stress (MPa); sigma (sigma) h Is the minimum ground stress (MPa); the arrows on the left indicate the internal pressure of the casing;
FIGS. 7 (a) and (b) are a finite element mechanical solid model and a mesh model, respectively, of the location of an established liner hanger according to one embodiment of the present invention; in the figure, sigma H Is the maximum ground stress (MPa); sigma (sigma) h Is the minimum ground stress (MPa); p (P) i Is the internal pressure of the sleeve (MPa);
FIG. 8 is a schematic diagram of the pressure distribution of the earth stress and its wellbore internal pressure transferred to the interfaces obtained in one embodiment of the invention; in the figure, radii of the cement sheath inner wall, the technical sleeve outer wall, the hydraulic cylinder inner wall, the central pipe inner wall and the central pipe outer wall, n1, n2, n3 and n4 respectively represent interface stages.
Detailed Description
The following describes in detail the embodiments of the present invention with reference to fig. 1-8.
The invention provides a quantitative safety evaluation method of a liner hanger, which comprises the following steps:
establishing a finite element mechanical solid model of the position of the liner hanger, wherein the finite element mechanical solid model sequentially comprises a profile stratum, a cement sheath, a technical sleeve, liquid, a liquid cylinder and a central pipe from the profile of the liner hanger inwards; the technical sleeve comprises: the hydraulic cylinder is positioned in the middle, the tieback cylinder is externally connected with the upper part of the hydraulic cylinder, and the tail pipe is externally connected with the lower part of the hydraulic cylinder;
converting the finite element mechanical entity model of the position of the liner hanger into a finite element mechanical grid model;
in a finite element mechanical grid model, carrying out finite element simulation on the pressure gradient of the outer wall of the tail pipe hanger and the tieback cylinder of the tail pipe hanger;
Establishing a prediction model of the pressure gradient of the outer wall of the pipe column in the finite element mechanical grid model along with the change of the internal pressure;
establishing a triaxial stress checking model of the technical sleeve;
and safety evaluation is carried out on the tail pipe hanger by adopting a prediction model of the pressure gradient of the outer wall of the pipe column along with the change of the internal pressure and a triaxial stress check model of the technical sleeve.
According to one embodiment of the invention, the finite element simulation of the pressure gradient of the outer wall of the liner hanger and the tieback thereof comprises the following steps: and (3) establishing a finite element simulation calculation model of the external ground stress of the hydraulic cylinder or the tieback cylinder by adopting plane strain, and applying the maximum ground stress and the minimum ground stress of the stratum to the finite element simulation calculation model of the external ground stress of the hydraulic cylinder or the tieback cylinder.
According to one embodiment of the invention, the finite element simulation of the pressure gradient of the liner hanger and its tieback tube outer wall further comprises: and establishing a finite element simulation calculation model of the external ground stress of the tail pipe by adopting plane strain, wherein the maximum ground stress and the minimum ground stress of the stratum are applied to the finite element simulation calculation model of the external ground stress of the tail pipe.
According to one embodiment of the invention, the finite element simulation of the pressure gradient of the liner hanger and its tieback tube outer wall further comprises: and calculating and storing pressure distribution of each contact interface, and dividing the pressure on the contact surface of the outer wall of the innermost hydraulic cylinder or the tieback cylinder by the well depth to obtain pressure gradient data.
According to a specific embodiment of the invention, based on the established finite element mechanical grid model, the ground stress and rock mechanical parameters, stratum rock, cement sheath and technical casing mechanical parameters are combined, and the ground stress and the wellbore internal pressure of the position are calculated to obtain pressure distribution of each contact interface.
According to one specific embodiment of the invention, a prediction model of the pressure gradient of the outer wall of the pipe column along with the change of the internal pressure is established, and the method specifically comprises the following steps:
obtaining the ground stress of the position of the hanger and the internal pressure P of the shaft and the hydraulic cylinder according to the position of the tail pipe hanger, the stratum pressure, the maximum horizontal ground stress gradient, the minimum horizontal ground stress gradient, the pressure of fracturing fluid in the pipe under the limiting working condition and the back pressure of the oil pipe required by the fracturing rupture disc i ；
Applying internal pressure P to well bore and cylinder in grid model of finite element mechanical entity model i And formation pressure P out ，P out Taking the maximum horizontal ground stress;
the suspension weight T of the tail pipe in the cement slurry is calculated according to the following formula:
T＝(ρ s -ρ m )A s L
wherein,
ρ s is the density of steel;
ρ m is the density of the well cementation slurry;
A s is the cross-sectional area of the tail pipe;
l is the length of the tail pipe;
applying a corresponding pretension force on the central tube, the pretension force being determined according to the suspension weight;
continuously changing pressure P in shaft i Obtaining corresponding contact pressure on each path；
And obtaining the change relation of the outer wall pressure of the hydraulic cylinder along with the internal pressure and the change relation of the outer wall pressure of the central tube along with the internal pressure under different working condition environments.
According to one specific embodiment of the invention, after obtaining the relationship of the pressure of the outer wall of the hydraulic cylinder with the internal pressure and the relationship of the pressure of the outer wall of the central tube with the internal pressure under different working conditions, the method further comprises the following steps:
the external pressure along with the internal pressure on the link path with the thinnest wall thickness of the hydraulic cylinder is averaged to be used as the external wall pressure of the hydraulic cylinder, and the internal pressure of the shaft and the external wall pressure P of the hydraulic cylinder are obtained o The relation between them is as follows:
P o ＝0.618Pi+30.5
obtaining the internal pressure P of the shaft i Pressure P with the outer wall of the central tube oc The relation between them is as follows:
P oc ＝0.322Pi+43.6
in the calculation process, judging whether the cement sheath and the profile stratum rock fail or not by adopting a Drucker-Prager failure criterion, wherein the expression is as follows:
in the method, in the process of the invention,
alpha and k are material parameters;
f is the infinitesimal strength of the profile stratum rock and MPa;
I 1 ＝σ 1 +σ 2 +σ 3
in the method, in the process of the invention,
is the friction angle of the material;
c is cohesion of the material;
σ 1 、σ 2 、σ 3 the maximum principal stress, the intermediate principal stress and the minimum principal stress are respectively;
I 1 is the first invariant of stress;
J 2 is the second invariant of stress deflection.
According to one embodiment of the present invention, the establishing a triaxial stress calibration model of a technical casing specifically includes:
The triaxial includes: z axis, r axis and circumference; the Z axis is downwards along the center of the shaft, the r axis is outwards along the radial direction of the shaft, and the circumferential direction is theta;
according to Lame formula of tube column in elastic mechanics theory, establishing axial stress sigma of technical sleeve z Radial stress sigma r And circumferential stress sigma θ The calculation model is as follows:
wherein,
P o is the external extrusion force (MPa) of the technical sleeve;
P i internal pressure (MPa) of the technical sleeve;
r o is the outer radius (mm) of the technical sleeve;
r i is the inner radius (mm) of the technical sleeve;
r is any radius (mm) of the technical sleeve;
δ θ circumferential stress (MPa) at any radius r for a technical sleeve;
δ Z axial stress (MPa) at any radius r for a technical sleeve;
δ r radial stress (MPa) at any radius r for a technical bushing;
F a is the axial load (N).
According to one specific embodiment of the invention, the safety evaluation of the liner hanger by adopting a prediction model of the pressure gradient of the outer wall of the tubular column along with the change of the internal pressure and a triaxial stress check model of the technical casing specifically comprises the following steps:
calculating the outer wall pressure of the hydraulic cylinder and the outer wall pressure of the central tube according to a prediction model of the outer wall pressure gradient of the tubular column along with the change of the internal pressure;
according to the calculated outer wall pressure of the hydraulic cylinder and the outer wall pressure of the central tube, adopting the axial stress sigma of the sleeve at any radius r z Radial stress sigma r And circumferential stress sigma θ Calculating the triaxial stress of the technical sleeve by using the calculation model;
and carrying out safety evaluation on the liner hanger according to the triaxial stress and the triaxial stress safety coefficient.
According to one specific embodiment of the invention, the safety evaluation of the liner hanger by adopting a prediction model of the pressure gradient of the outer wall of the tubular column along with the change of the internal pressure and a triaxial stress check model of the technical casing specifically comprises the following steps:
according to the internal pressure of the shaft and the external wall pressure P of the hydraulic cylinder o The relation between the two is used for calculating the outer wall pressure P of the hydraulic cylinder when the internal pressure Pi of any given shaft is calculated o ；
According to the internal pressure P of the shaft i Pressure P with the outer wall of the central tube oc The relation between the two is used for calculating the outer wall pressure P of the central pipe when the internal pressure Pi of the well bore is given oc ；
Using technical sleeve axial stress sigma z Radial stress sigma r And circumferential stress sigma θ Calculating radial stress, circumferential stress and axial stress of the technical sleeve by using the calculation model;
judging whether the triaxial stress of the technical sleeve meets the following safety coefficient S of the triaxial stress according to the fourth strength theory Von-Mises yield strength criterion type 3 And (2) not less than 1.25, if all the conditions are met, the liner hanger is in a safe state, otherwise, the liner hanger is in a dangerous state:
in the method, in the process of the invention,
σ VME Triaxial stress (MPa) for technical bushings;
Y p tubing yield strength (MPa) for technical casing;
S 3 is the safety factor of triaxial stress.
According to one embodiment of the present invention, the method for converting the finite element mechanical entity model of the position of the liner hanger into the finite element mechanical grid model specifically includes:
the finite element mechanical entity model adopts 8-node unit division structural grids, contact finite units are adopted among different material interfaces, and 5 groups of contact pair unit models are established.
Example 1
The method for evaluating the quantitative safety of the liner hanger according to the present invention will be described in detail below according to one embodiment of the present invention.
The invention provides a quantitative safety evaluation method of a liner hanger, which comprises the following steps:
establishing a finite element mechanical solid model of the position of the liner hanger, wherein the finite element mechanical solid model sequentially comprises a profile stratum, a cement sheath, a technical sleeve, liquid, a liquid cylinder and a central pipe from the profile of the liner hanger inwards; the technical sleeve comprises: the hydraulic cylinder is positioned in the middle, the tieback cylinder is externally connected with the upper part of the hydraulic cylinder, and the tail pipe is externally connected with the lower part of the hydraulic cylinder;
converting the finite element mechanical entity model of the position of the liner hanger into a finite element mechanical grid model;
In a finite element mechanical grid model, carrying out finite element simulation on the pressure gradient of the outer wall of the tail pipe hanger and the tieback cylinder of the tail pipe hanger;
establishing a prediction model of the pressure gradient of the outer wall of the pipe column in the finite element mechanical grid model along with the change of the internal pressure;
establishing a triaxial stress checking model of the technical sleeve;
and safety evaluation is carried out on the tail pipe hanger by adopting a prediction model of the pressure gradient of the outer wall of the pipe column along with the change of the internal pressure and a triaxial stress check model of the technical sleeve.
Example 2
The method for evaluating the quantitative safety of the liner hanger according to the present invention will be described in detail below according to one embodiment of the present invention.
The invention provides a quantitative safety evaluation method of a liner hanger, which comprises the following steps:
establishing a finite element mechanical solid model of the position of the liner hanger, wherein the finite element mechanical solid model sequentially comprises a profile stratum, a cement sheath, a technical sleeve, liquid, a liquid cylinder and a central pipe from the profile of the liner hanger inwards; the technical sleeve comprises: the hydraulic cylinder is positioned in the middle, the tieback cylinder is externally connected with the upper part of the hydraulic cylinder, and the tail pipe is externally connected with the lower part of the hydraulic cylinder;
converting the finite element mechanical entity model of the position of the liner hanger into a finite element mechanical grid model;
In a finite element mechanical grid model, carrying out finite element simulation on the pressure gradient of the outer wall of the tail pipe hanger and the tieback cylinder of the tail pipe hanger;
establishing a prediction model of the pressure gradient of the outer wall of the pipe column in the finite element mechanical grid model along with the change of the internal pressure;
establishing a triaxial stress checking model of the technical sleeve;
and safety evaluation is carried out on the tail pipe hanger by adopting a prediction model of the pressure gradient of the outer wall of the pipe column along with the change of the internal pressure and a triaxial stress check model of the technical sleeve.
The finite element simulation of the pressure gradient of the outer wall of the liner hanger and the tieback cylinder specifically comprises the following steps:
adopting plane strain to establish a finite element simulation calculation model of external ground stress of a hydraulic cylinder or a tieback cylinder of the hanger, and applying the maximum ground stress and the minimum ground stress of a stratum to the finite element simulation calculation model of the external ground stress of the hydraulic cylinder or the tieback cylinder of the hanger;
adopting plane strain to establish a finite element simulation calculation model of external ground stress of the tail pipe, and applying the maximum ground stress and the minimum ground stress of the stratum to the finite element simulation calculation model of the external ground stress of the tail pipe;
based on the established finite element mechanical grid model, combining the ground stress and rock mechanical parameters, stratum rock, cement sheath and technical sleeve mechanical parameters, and calculating the ground stress and the internal pressure of the well bore of the position to obtain pressure distribution of each contact interface;
And (5) preserving pressure distribution of each contact interface, and dividing the pressure on the contact surface of the outer wall of the innermost hydraulic cylinder or the tieback cylinder by the well depth to obtain pressure gradient data.
Example 3
The method for evaluating the quantitative safety of the liner hanger according to the present invention will be described in detail below according to one embodiment of the present invention.
The invention provides a quantitative safety evaluation method of a liner hanger, which comprises the following steps:
establishing a finite element mechanical solid model of the position of the liner hanger, wherein the finite element mechanical solid model sequentially comprises a profile stratum, a cement sheath, a technical sleeve, liquid, a liquid cylinder and a central pipe from the profile of the liner hanger inwards; the technical sleeve comprises: the hydraulic cylinder is positioned in the middle, the tieback cylinder is externally connected with the upper part of the hydraulic cylinder, and the tail pipe is externally connected with the lower part of the hydraulic cylinder;
converting the finite element mechanical entity model of the position of the liner hanger into a finite element mechanical grid model;
in a finite element mechanical grid model, carrying out finite element simulation on the pressure gradient of the outer wall of the tail pipe hanger and the tieback cylinder of the tail pipe hanger;
establishing a prediction model of the pressure gradient of the outer wall of the pipe column in the finite element mechanical grid model along with the change of the internal pressure;
establishing a triaxial stress checking model of the technical sleeve;
And safety evaluation is carried out on the tail pipe hanger by adopting a prediction model of the pressure gradient of the outer wall of the pipe column along with the change of the internal pressure and a triaxial stress check model of the technical sleeve.
Establishing a prediction model of the pressure gradient of the outer wall of the pipe column along with the change of the internal pressure, which specifically comprises the following steps:
obtaining the ground stress of the position of the hanger and the internal pressure P of the shaft and the hydraulic cylinder according to the position of the tail pipe hanger, the stratum pressure, the maximum horizontal ground stress gradient, the minimum horizontal ground stress gradient, the pressure of fracturing fluid in the pipe under the limiting working condition and the back pressure of the oil pipe required by the fracturing rupture disc i ；
Applying internal pressure P to well bore and cylinder in grid model of finite element mechanical entity model i And formation pressure P out ，P out Taking the maximum horizontal ground stress;
the suspension weight T of the tail pipe in the cement slurry is calculated according to the following formula:
T＝(ρ s -ρ m )A s L
wherein,
ρ s is the density of steel;
ρ m is the density of the well cementation slurry;
A s is the cross-sectional area of the tail pipe;
l is the length of the tail pipe;
applying a corresponding pretension force on the central tube, the pretension force being determined according to the suspension weight;
continuously changing pressure P in shaft i Obtaining corresponding contact pressure on each path;
and obtaining the change relation of the outer wall pressure of the hydraulic cylinder along with the internal pressure and the change relation of the outer wall pressure of the central tube along with the internal pressure under different working condition environments.
The wall thickness of the hydraulic cylinder is minimizedThe external pressure along with the internal pressure change on the link path is averaged to be used as the external wall pressure of the hydraulic cylinder to obtain the internal pressure of the shaft and the external wall pressure P of the hydraulic cylinder o The relation between them is as follows:
P o ＝0.618Pi+30.5
obtaining the internal pressure P of the shaft i Pressure P with the outer wall of the central tube oc The relation between them is as follows:
P oc ＝0.322Pi+43.6
in the calculation process, judging whether the cement sheath and the profile stratum rock fail or not by adopting a Drucker-Prager failure criterion, wherein the expression is as follows:
in the method, in the process of the invention,
alpha and k are material parameters;
f is the infinitesimal strength of the profile stratum rock and MPa;
I 1 ＝σ 1 +σ 2 +σ 3
in the method, in the process of the invention,
is the friction angle of the material;
c is cohesion of the material;
σ 1 、σ 2 、σ 3 respectively the maximum principal stress,Intermediate principal stress, minimum principal stress;
I 1 is the first invariant of stress;
J 2 is the second invariant of stress deflection.
The triaxial stress checking model for establishing the technical sleeve specifically comprises the following steps:
the triaxial includes: z axis, r axis and circumference; the Z axis is downwards along the center of the shaft, the r axis is outwards along the radial direction of the shaft, and the circumferential direction is theta;
according to Lame formula of tube column in elastic mechanics theory, establishing axial stress sigma of technical sleeve z Radial stress sigma r And circumferential stress sigma θ The calculation model is as follows:
wherein,
P o is the external extrusion force (MPa) of the technical sleeve;
P i Internal pressure (MPa) of the technical sleeve;
r o is the outer radius (mm) of the technical sleeve;
r i is the inner radius (mm) of the technical sleeve;
r is any radius (mm) of the technical sleeve;
δ θ circumferential stress (MPa) at any radius r for a technical sleeve;
δ Z axial stress (MPa) at any radius r for a technical sleeve;
δ r radial stress (MPa) at any radius r for a technical bushing;
F a is the axial load (N).
The safety evaluation of the liner hanger by adopting a prediction model of the pressure gradient of the outer wall of the pipe column along with the change of the internal pressure and a triaxial stress check model of the technical sleeve specifically comprises the following steps:
calculating the outer wall pressure of the hydraulic cylinder and the outer wall pressure of the central tube according to a prediction model of the outer wall pressure gradient of the tubular column along with the change of the internal pressure;
according to the calculated outer wall pressure of the hydraulic cylinder and the outer wall pressure of the central tube, adopting the axial stress sigma of the sleeve at any radius r z Radial stress sigma r And circumferential stress sigma θ Calculating the triaxial stress of the technical sleeve by using the calculation model;
and carrying out safety evaluation on the liner hanger according to the triaxial stress and the triaxial stress safety coefficient.
Example 4
The method for evaluating the quantitative safety of the liner hanger according to the present invention will be described in detail below according to one embodiment of the present invention.
The invention provides a quantitative safety evaluation method of a liner hanger, which comprises the following steps:
Establishing a finite element mechanical solid model of the position of the liner hanger, wherein the finite element mechanical solid model sequentially comprises a profile stratum, a cement sheath, a technical sleeve, liquid, a liquid cylinder and a central pipe from the profile of the liner hanger inwards; the technical sleeve comprises: the hydraulic cylinder is positioned in the middle, the tieback cylinder is externally connected with the upper part of the hydraulic cylinder, and the tail pipe is externally connected with the lower part of the hydraulic cylinder;
converting the finite element mechanical entity model of the position of the liner hanger into a finite element mechanical grid model;
in a finite element mechanical grid model, carrying out finite element simulation on the pressure gradient of the outer wall of the tail pipe hanger and the tieback cylinder of the tail pipe hanger;
establishing a prediction model of the pressure gradient of the outer wall of the pipe column in the finite element mechanical grid model along with the change of the internal pressure;
establishing a triaxial stress checking model of the technical sleeve;
and safety evaluation is carried out on the tail pipe hanger by adopting a prediction model of the pressure gradient of the outer wall of the pipe column along with the change of the internal pressure and a triaxial stress check model of the technical sleeve.
Establishing a prediction model of the pressure gradient of the outer wall of the pipe column along with the change of the internal pressure, which specifically comprises the following steps:
obtaining the ground stress of the position of the hanger and the internal pressure P of the shaft and the hydraulic cylinder according to the position of the tail pipe hanger, the stratum pressure, the maximum horizontal ground stress gradient, the minimum horizontal ground stress gradient, the pressure of fracturing fluid in the pipe under the limiting working condition and the back pressure of the oil pipe required by the fracturing rupture disc i ；
Applying internal pressure P to well bore and cylinder in grid model of finite element mechanical entity model i And formation pressure P out ，P out Taking the maximum horizontal ground stress;
the suspension weight T of the tail pipe in the cement slurry is calculated according to the following formula:
T＝(ρ s -ρ m )A s L
wherein,
ρ s is the density of steel;
ρ m is the density of the well cementation slurry;
A s is the cross-sectional area of the tail pipe;
l is the length of the tail pipe;
applying a corresponding pretension force on the central tube, the pretension force being determined according to the suspension weight;
continuously changing pressure P in shaft i Obtaining corresponding contact pressure on each path;
and obtaining the change relation of the outer wall pressure of the hydraulic cylinder along with the internal pressure and the change relation of the outer wall pressure of the central tube along with the internal pressure under different working condition environments.
The external pressure along with the internal pressure on the link path with the thinnest wall thickness of the hydraulic cylinder is averaged to be used as the external wall pressure of the hydraulic cylinder, and the internal pressure of the shaft and the external wall pressure P of the hydraulic cylinder are obtained o The relation between them is as follows:
P o ＝0.618Pi+30.5
obtaining the internal pressure P of the shaft i Pressure P with the outer wall of the central tube oc The relation between them is as follows:
P oc ＝0.322Pi+43.6
in the calculation process, judging whether the cement sheath and the profile stratum rock fail or not by adopting a Drucker-Prager failure criterion, wherein the expression is as follows:
in the method, in the process of the invention,
alpha and k are material parameters;
f is the infinitesimal strength of the profile stratum rock and MPa;
I 1 ＝σ 1 +σ 2 +σ 3
in the method, in the process of the invention,
is the friction angle of the material;
C is cohesion of the material;
σ 1 、σ 2 、σ 3 the maximum principal stress, the intermediate principal stress and the minimum principal stress are respectively;
I 1 is the first invariant of stress;
J 2 is the second invariant of stress deflection.
The triaxial stress checking model for establishing the technical sleeve specifically comprises the following steps:
the triaxial includes: z axis, r axis and circumference; the Z axis is downwards along the center of the shaft, the r axis is outwards along the radial direction of the shaft, and the circumferential direction is theta;
according to Lame formula of tube column in elastic mechanics theory, establishing axial stress sigma of technical sleeve z Radial stress sigma r And circumferential stress sigma θ The calculation model is as follows:
wherein,
P o is the external extrusion force (MPa) of the technical sleeve;
P i internal pressure (MPa) of the technical sleeve;
r o is the outer radius (mm) of the technical sleeve;
r i is the inner radius (mm) of the technical sleeve;
r is any radius (mm) of the technical sleeve;
δ θ circumferential stress (MPa) at any radius r for a technical sleeve;
δ Z axial stress (MPa) at any radius r for a technical sleeve;
δ r radial stress (MPa) at any radius r for a technical bushing;
F a is the axial load (N).
The safety evaluation of the liner hanger by adopting a prediction model of the pressure gradient of the outer wall of the pipe column along with the change of the internal pressure and a triaxial stress check model of the technical sleeve specifically comprises the following steps:
according to the internal pressure of the shaft and the external wall pressure P of the hydraulic cylinder o The relation between the two is used for calculating the outer wall pressure P of the hydraulic cylinder when the internal pressure Pi of any given shaft is calculated o ；
According to the internal pressure P of the shaft i Pressure P with the outer wall of the central tube oc The relation between the two is used for calculating the outer wall pressure P of the central pipe when the internal pressure Pi of the well bore is given oc ；
Using technical sleeve axial stress sigma z Radial stress sigma r And circumferential stress sigma θ Calculating radial stress, circumferential stress and axial stress of the technical sleeve by using the calculation model;
judging whether the triaxial stress of the technical sleeve meets the following safety coefficient S of the triaxial stress according to the fourth strength theory Von-Mises yield strength criterion type 3 And (2) not less than 1.25, if all the conditions are met, the liner hanger is in a safe state, otherwise, the liner hanger is in a dangerous state:
in the method, in the process of the invention,
σ VME triaxial stress (MPa) for technical bushings;
Y p tubing yield strength (MPa) for technical casing;
S 3 is the safety factor of triaxial stress.
Example 5
The method for evaluating the quantitative safety of the liner hanger according to the present invention will be described in detail below according to one embodiment of the present invention.
The invention provides a quantitative safety evaluation method of a liner hanger, which comprises the following steps:
establishing a finite element mechanical solid model of the position of the liner hanger, wherein the finite element mechanical solid model sequentially comprises a profile stratum, a cement sheath, a technical sleeve, liquid, a liquid cylinder and a central pipe from the profile of the liner hanger inwards; the technical sleeve comprises: the hydraulic cylinder is positioned in the middle, the tieback cylinder is externally connected with the upper part of the hydraulic cylinder, and the tail pipe is externally connected with the lower part of the hydraulic cylinder;
Converting the finite element mechanical entity model of the position of the liner hanger into a finite element mechanical grid model; the finite element mechanical entity model adopts 8-node units to divide structural grids, contact finite units are adopted among different material interfaces, and 5 groups of contact pair unit models are established;
in a finite element mechanical grid model, carrying out finite element simulation on the pressure gradient of the outer wall of the tail pipe hanger and the tieback cylinder of the tail pipe hanger;
establishing a prediction model of the pressure gradient of the outer wall of the pipe column in the finite element mechanical grid model along with the change of the internal pressure;
establishing a triaxial stress checking model of the technical sleeve;
and safety evaluation is carried out on the tail pipe hanger by adopting a prediction model of the pressure gradient of the outer wall of the pipe column along with the change of the internal pressure and a triaxial stress check model of the technical sleeve.
The finite element simulation of the pressure gradient of the outer wall of the liner hanger and the tieback cylinder specifically comprises the following steps:
adopting plane strain to establish a finite element simulation calculation model of external ground stress of a hydraulic cylinder or a tieback cylinder of the hanger, and applying the maximum ground stress and the minimum ground stress of a stratum to the finite element simulation calculation model of the external ground stress of the hydraulic cylinder or the tieback cylinder of the hanger;
adopting plane strain to establish a finite element simulation calculation model of external ground stress of the tail pipe, and applying the maximum ground stress and the minimum ground stress of the stratum to the finite element simulation calculation model of the external ground stress of the tail pipe;
Based on the established finite element mechanical grid model, combining the ground stress and rock mechanical parameters, stratum rock, cement sheath and technical sleeve mechanical parameters, and calculating the ground stress and the internal pressure of the well bore of the position to obtain pressure distribution of each contact interface;
and (5) preserving pressure distribution of each contact interface, and dividing the pressure on the contact surface of the outer wall of the innermost hydraulic cylinder or the tieback cylinder by the well depth to obtain pressure gradient data.
Establishing a prediction model of the pressure gradient of the outer wall of the pipe column along with the change of the internal pressure, which specifically comprises the following steps:
obtaining the ground stress of the position of the hanger and the internal pressure P of the shaft and the hydraulic cylinder according to the position of the tail pipe hanger, the stratum pressure, the maximum horizontal ground stress gradient, the minimum horizontal ground stress gradient, the pressure of fracturing fluid in the pipe under the limiting working condition and the back pressure of the oil pipe required by the fracturing rupture disc i ；
Applying internal pressure P to well bore and cylinder in grid model of finite element mechanical entity model i And formation pressure P out ，P out Taking the maximum horizontal ground stress;
the suspension weight T of the tail pipe in the cement slurry is calculated according to the following formula:
T＝(ρ s -ρ m )A s L
wherein,
ρ s is the density of steel;
ρ m is the density of the well cementation slurry;
A s is the cross-sectional area of the tail pipe;
l is the length of the tail pipe;
applying a corresponding pretension force on the central tube, the pretension force being determined according to the suspension weight;
Continuously changing pressure P in shaft i Obtaining corresponding contact pressure on each path;
and obtaining the change relation of the outer wall pressure of the hydraulic cylinder along with the internal pressure and the change relation of the outer wall pressure of the central tube along with the internal pressure under different working condition environments.
The external pressure along with the internal pressure on the link path with the thinnest wall thickness of the hydraulic cylinder is averaged to be used as the external wall pressure of the hydraulic cylinder, and the internal pressure of the shaft and the external wall pressure P of the hydraulic cylinder are obtained o The relation between them is as follows:
P o ＝0.618Pi+30.5
obtaining the internal pressure P of the shaft i Pressure P with the outer wall of the central tube oc The relation between them is as follows:
P oc ＝0.322Pi+43.6
in the calculation process, judging whether the cement sheath and the profile stratum rock fail or not by adopting a Drucker-Prager failure criterion, wherein the expression is as follows:
in the method, in the process of the invention,
alpha and k are material parameters;
f is the infinitesimal strength of the profile stratum rock and MPa;
I 1 ＝σ 1 +σ 2 +σ 3
in the method, in the process of the invention,
is the friction angle of the material;
c is cohesion of the material;
σ 1 、σ 2 、σ 3 the maximum principal stress, the intermediate principal stress and the minimum principal stress are respectively;
I 1 is the first invariant of stress;
J 2 is the second invariant of stress deflection.
The triaxial stress checking model for establishing the technical sleeve specifically comprises the following steps:
the triaxial includes: z axis, r axis and circumference; the Z axis is downwards along the center of the shaft, the r axis is outwards along the radial direction of the shaft, and the circumferential direction is theta;
According to Lame formula of tube column in elastic mechanics theory, establishing axial stress sigma of technical sleeve z Radial stressσ r And circumferential stress sigma θ The calculation model is as follows:
/>
wherein,
P o is the external extrusion force (MPa) of the technical sleeve;
P i internal pressure (MPa) of the technical sleeve;
r o is the outer radius (mm) of the technical sleeve;
r i is the inner radius (mm) of the technical sleeve;
r is any radius (mm) of the technical sleeve;
δ θ circumferential stress (MPa) at any radius r for a technical sleeve;
δ Z axial stress (MPa) at any radius r for a technical sleeve;
δ r radial stress (MPa) at any radius r for a technical bushing;
F a is the axial load (N).
The safety evaluation of the liner hanger by adopting a prediction model of the pressure gradient of the outer wall of the pipe column along with the change of the internal pressure and a triaxial stress check model of the technical sleeve specifically comprises the following steps:
according to the internal pressure of the shaft and the external wall pressure P of the hydraulic cylinder o The relation between the two is used for calculating the outer wall pressure P of the hydraulic cylinder when the internal pressure Pi of any given shaft is calculated o ；
According to the internal pressure P of the shaft i Pressure P with the outer wall of the central tube oc The relation between the two is used for calculating the outer wall pressure P of the central pipe when the internal pressure Pi of the well bore is given oc ；
Using technical sleeve axial stress sigma z Radial stress sigma r And circumferential stress sigma θ Calculating radial stress, circumferential stress and axial stress of the technical sleeve by using the calculation model;
Judging whether the triaxial stress of the technical sleeve meets the following safety coefficient S of the triaxial stress according to the fourth strength theory Von-Mises yield strength criterion type 3 And (2) not less than 1.25, if all the conditions are met, the liner hanger is in a safe state, otherwise, the liner hanger is in a dangerous state:
in the method, in the process of the invention,
σ VME triaxial stress (MPa) for technical bushings;
Y p tubing yield strength (MPa) for technical casing;
S 3 is the safety factor of triaxial stress.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.
Claims (11)
1. The quantitative safety evaluation method for the liner hanger is characterized by comprising the following steps of:
establishing a finite element mechanical solid model of the position of the liner hanger, wherein the finite element mechanical solid model sequentially comprises a profile stratum, a cement sheath, a technical sleeve, liquid, a liquid cylinder and a central pipe from the profile of the liner hanger inwards; the technical sleeve comprises: the hydraulic cylinder is positioned in the middle, the tieback cylinder is externally connected with the upper part of the hydraulic cylinder, and the tail pipe is externally connected with the lower part of the hydraulic cylinder;
Converting the finite element mechanical entity model of the position of the liner hanger into a finite element mechanical grid model;
in a finite element mechanical grid model, carrying out finite element simulation on the pressure gradient of the outer wall of the tail pipe hanger and the tieback cylinder of the tail pipe hanger;
establishing a prediction model of the pressure gradient of the outer wall of the pipe column in the finite element mechanical grid model along with the change of the internal pressure;
establishing a triaxial stress checking model of the technical sleeve;
and safety evaluation is carried out on the tail pipe hanger by adopting a prediction model of the pressure gradient of the outer wall of the pipe column along with the change of the internal pressure and a triaxial stress check model of the technical sleeve.
2. The liner hanger quantitative safety evaluation method according to claim 1, wherein the finite element simulation of the pressure gradient of the liner hanger and the outer wall of the tieback tube thereof comprises: and (3) establishing a finite element simulation calculation model of the external ground stress of the hydraulic cylinder or the tieback cylinder by adopting plane strain, and applying the maximum ground stress and the minimum ground stress of the stratum to the finite element simulation calculation model of the external ground stress of the hydraulic cylinder or the tieback cylinder.
3. The liner hanger quantitative safety evaluation method according to claim 2, wherein the finite element simulation of the pressure gradient of the liner hanger and its tieback tube outer wall further comprises: and establishing a finite element simulation calculation model of the external ground stress of the tail pipe by adopting plane strain, wherein the maximum ground stress and the minimum ground stress of the stratum are applied to the finite element simulation calculation model of the external ground stress of the tail pipe.
4. The liner hanger quantitative safety evaluation method of claim 3, wherein performing finite element simulation of the pressure gradient of the liner hanger and its tieback tube outer wall further comprises: and calculating and storing pressure distribution of each contact interface, and dividing the pressure on the contact surface of the outer wall of the innermost hydraulic cylinder or the tieback cylinder by the well depth to obtain pressure gradient data.
5. The method for quantitative safety evaluation of a liner hanger according to claim 4, wherein the pressure distribution of each contact interface is obtained based on the established finite element mechanical grid model by combining the ground stress with the rock mechanical parameters, the stratum rock, the cement sheath and the technical casing mechanical parameters, and calculating the ground stress and the internal pressure of the well bore at the position.
6. The method for quantitatively evaluating the safety of the liner hanger according to claim 1, wherein the step of establishing a predictive model of the pressure gradient of the outer wall of the pipe string along with the change of the internal pressure is specifically included:
obtaining the ground stress of the position of the hanger and the internal pressure P of the shaft and the hydraulic cylinder according to the position of the tail pipe hanger, the stratum pressure, the maximum horizontal ground stress gradient, the minimum horizontal ground stress gradient, the pressure of fracturing fluid in the pipe under the limiting working condition and the back pressure of the oil pipe required by the fracturing rupture disc i ；
Applying internal pressure P to well bore and cylinder in grid model of finite element mechanical entity model i And formation pressure P out ，P out Taking the maximum horizontal ground stress;
the suspension weight T of the tail pipe in the cement slurry is calculated according to the following formula:
T＝(ρ s -ρ m )A s L
wherein,
ρ s is the density of steel;
ρ m is the density of the well cementation slurry;
A s is the cross-sectional area of the tail pipe;
l is the length of the tail pipe;
applying a corresponding pretension force on the central tube, the pretension force being determined according to the suspension weight;
continuously changing pressure P in shaft i Obtaining corresponding contact pressure on each path;
and obtaining the change relation of the outer wall pressure of the hydraulic cylinder along with the internal pressure and the change relation of the outer wall pressure of the central tube along with the internal pressure under different working condition environments.
7. The method for quantitatively evaluating the safety of a liner hanger according to claim 6, further comprising the steps of, after obtaining the relationship between the pressure of the outer wall of the cylinder and the pressure of the outer wall of the center pipe with the internal pressure under different working conditions:
the external pressure along with the internal pressure on the link path with the thinnest wall thickness of the hydraulic cylinder is averaged to be used as the external wall pressure of the hydraulic cylinder, and the internal pressure of the shaft and the external wall pressure P of the hydraulic cylinder are obtained o The relation between them is as follows:
P o ＝0.618Pi+30.5
obtaining the internal pressure P of the shaft i Pressure P with the outer wall of the central tube oc The relation between them is as follows:
P oc ＝0.322Pi+43.6
In the calculation process, judging whether the cement sheath and the profile stratum rock fail or not by adopting a Drucker-Prager failure criterion, wherein the expression is as follows:
in the method, in the process of the invention,
alpha and k are material parameters;
f is the infinitesimal strength of the profile stratum rock and MPa;
I 1 ＝σ 1 +σ 2 +σ 3
in the method, in the process of the invention,
is the friction angle of the material;
c is cohesion of the material;
σ 1 、σ 2 、σ 3 the maximum principal stress, the intermediate principal stress and the minimum principal stress are respectively;
I 1 is the first invariant of stress;
J 2 is the second invariant of stress deflection.
8. The method for quantitatively evaluating the safety of the liner hanger according to claim 7, wherein the establishing a triaxial stress check model of the technical casing specifically comprises:
the triaxial includes: z axis, r axis and circumference; the Z axis is downwards along the center of the shaft, the r axis is outwards along the radial direction of the shaft, and the circumferential direction is theta;
according to Lame formula of tube column in elastic mechanics theory, establishing axial stress sigma of technical sleeve z Radial stress sigma r And circumferential stress sigma θ The calculation model is as follows:
wherein,
P o is the external extrusion force (MPa) of the technical sleeve;
P i for internal pressure of technical bushingsForce (MPa);
r o is the outer radius (mm) of the technical sleeve;
r i is the inner radius (mm) of the technical sleeve;
r is any radius (mm) of the technical sleeve;
δ θ circumferential stress (MPa) at any radius r for a technical sleeve;
δ Z Axial stress (MPa) at any radius r for a technical sleeve;
δ r radial stress (MPa) at any radius r for a technical bushing;
F a is the axial load (N).
9. The method for quantitatively evaluating the safety of the liner hanger according to claim 8, wherein the safety evaluation of the liner hanger by using a prediction model of the pressure gradient of the outer wall of the pipe string along with the change of the internal pressure and a triaxial stress check model of the technical casing specifically comprises:
calculating the outer wall pressure of the hydraulic cylinder and the outer wall pressure of the central tube according to a prediction model of the outer wall pressure gradient of the tubular column along with the change of the internal pressure;
according to the calculated outer wall pressure of the hydraulic cylinder and the outer wall pressure of the central tube, adopting the axial stress sigma of the sleeve at any radius r z Radial stress sigma r And circumferential stress sigma θ Calculating the triaxial stress of the technical sleeve by using the calculation model;
and carrying out safety evaluation on the liner hanger according to the triaxial stress and the triaxial stress safety coefficient.
10. The method for quantitatively evaluating the safety of the liner hanger according to claim 9, wherein the safety evaluation of the liner hanger by using a prediction model of the pressure gradient of the outer wall of the pipe string along with the change of the internal pressure and a triaxial stress check model of the technical casing specifically comprises:
according to the internal pressure of the shaft and the external wall pressure P of the hydraulic cylinder o The relation between the two is used for calculating the outer wall pressure P of the hydraulic cylinder when the internal pressure Pi of any given shaft is calculated o ；
According to the internal pressure P of the shaft i Pressure P with the outer wall of the central tube oc The relation between the two is used for calculating the outer wall pressure P of the central pipe when the internal pressure Pi of the well bore is given oc ；
Using technical sleeve axial stress sigma z Radial stress sigma r And circumferential stress sigma θ Calculating radial stress, circumferential stress and axial stress of the technical sleeve by using the calculation model;
judging whether the triaxial stress of the technical sleeve meets the following safety coefficient S of the triaxial stress according to the fourth strength theory Von-Mises yield strength criterion type 3 And (2) not less than 1.25, if all the conditions are met, the liner hanger is in a safe state, otherwise, the liner hanger is in a dangerous state:
in the method, in the process of the invention,
σ VME triaxial stress (MPa) for technical bushings;
Y p tubing yield strength (MPa) for technical casing;
S 3 is the safety factor of triaxial stress.
11. The method for quantitatively evaluating the safety of the liner hanger according to claim 5, wherein the step of converting the finite element mechanical solid model of the position of the liner hanger into the finite element mechanical mesh model comprises the following steps:
the finite element mechanical entity model adopts 8-node unit division structural grids, contact finite units are adopted among different material interfaces, and 5 groups of contact pair unit models are established.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210909994.3A CN117521435A (en) | 2022-07-29 | 2022-07-29 | Quantitative safety evaluation method for liner hanger |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210909994.3A CN117521435A (en) | 2022-07-29 | 2022-07-29 | Quantitative safety evaluation method for liner hanger |
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