CN117268928A - Full-size nonmetal reinforced flexible composite pipe service life prediction method - Google Patents
Full-size nonmetal reinforced flexible composite pipe service life prediction method Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
- G01N3/10—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces generated by pneumatic or hydraulic pressure
- G01N3/12—Pressure testing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0001—Type of application of the stress
- G01N2203/0003—Steady
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
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- G01N2203/0048—Hydraulic means
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- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
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Abstract
The invention discloses a full-size nonmetal reinforced flexible composite pipe life prediction method, belongs to the technical field of nonmetal reinforced flexible composite pipe life prediction and evaluation, and solves the technical problems of huge workload, long test period and uncontrollable effective data in the test process when flexible composite pipe life prediction is performed in the prior art. According to the method disclosed by the invention, under three temperature conditions, each temperature condition is selected to obtain the pipe failure time under each pressure value, then the pipe failure time and pressure curve under different temperature conditions and the corresponding linear equation are made, 50% of the ultimate bearing strength of the non-metal pipe for the full-size oil-gas field environment at room temperature is substituted into the linear equation as a threshold value to obtain the corresponding time, finally, a non-metal reinforced composite pipe temperature-time Arrhenius relation diagram is built, the service life of the pipe can be accurately predicted through the service temperature, and basic support is provided for the long-term safety application of the non-metal pipe for the standard full-size oil-gas field environment.
Description
Technical Field
The invention belongs to the technical field of non-metal reinforced flexible composite pipe life prediction and evaluation thereof, and particularly relates to a full-size non-metal reinforced flexible composite pipe life prediction method.
Background
At present, the traditional oil and gas transportation is mainly realized by virtue of metal pipelines, and the defect is that the metal pipelines are used for corrosive media such as hydrogen sulfide (H) 2 S) and carbon dioxide (CO) 2 ) And the pipeline perforation failure and oil gas leakage are easy to be caused under the corrosion. In recent years, thermoplastic pipes are also gradually applied to acidic environments, but because the pressure bearing capacity of the materials is limited, the materials can only be applied to pressure pipelines below 1.6MPa, and the field requirements of oil fields cannot be met, so that nonmetal reinforced thermoplastic pipes are increasingly widely applied for improving the conveying pressure of the thermoplastic pipes. A non-metal reinforced thermoplastic pipe is a composite pipe having a multi-layer structure, typically comprising an inner liner layer, a non-metal reinforcing layer and an outer cladding layer. Generally, the design life of non-metal and composite material pipes is over 20 years, but when the pipes are combined under working conditions of high temperature, high pressure and the like, the ageing process of thermoplastic plastics in direct contact with oil-gas media is accelerated, the failure morphology of the materials is various (cracks, holes, bubbles and the like), and the failure modes are complex and alternating (toughness, brittleness, degradation and the like).
The prior art pressure rating test method for full-size nonmetallic composite tubing, referring to standard API 15s 5.3.3, MPR of pfr should be determined by performing a series of creep rupture tests under rated test temperature and constant pressure conditions. The test was performed according to procedure B, defined in ASTM D2992-12, with regression calculations not including data points having a failure time of less than 10 hours, and the specific test protocol is shown in Table 1. The temperature of the evaluation test is selected by the manufacturer and should not be lower than the design temperature of the product under any application condition, and the evaluation test temperature can be recommended to be 65 ℃ (the polyester fiber reinforced polyethylene composite tube). The failure mode allowed is a tensile failure of the reinforcement. If the failure mode is not a tensile failure of the reinforcement during the assessment test, such as the pipe backing out of the joint or sleeve, the test results should be discarded when calculating the average or plotting the data, part of the data acquisition in the prior art flexible composite pipe pressure rating test is shown in FIG. 1.
TABLE 1 MPR failure point distribution (specified with reference to ASTM D2992-12)
| Time to failure (h) | Failure point | Design failure point |
| 10～1000 | At least 4 | 11 pieces of |
| 1000～6000 | At least 3 | 3 pieces of |
| Greater than 6000 | At least 3 | 3 pieces of |
| Greater than 10000 | At least 1 | 1 number of |
| Total number of | At least 18 | 18 |
The specific implementation scheme of the prior art is as follows:
a) Carrying out a water pressure bursting strength test at 65 ℃ on the test sample tube to obtain an ultimate strength value;
b) According to the ultimate strength value, presuming a pressure value corresponding to the failure time of 10-1000 hours, and completing the collection of 11 failure points of two specifications within 2 months;
c) According to the distribution of failure points of 10-1000 hours, initially making a regression curve, calculating the corresponding relation between the subsequent test time and the pressure distribution, and giving out the pressure value corresponding to the failure point of the subsequent test;
d) Collecting the 6000-10000 h test points, wherein the total number of the test points is 3;
e) Collecting work of 1000-6000 h test points is carried out, and the total number of the test points is 3.
As can be seen from the above implementation steps and the attached FIG. 1, the pressure rating test specified by the API 15S comprises the collection of 18 effective data points, and the maximum test time is 10000 hours, so that the rating method has huge workload, long test period and uncontrollable effective data in the test process.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a full-size nonmetal reinforced flexible composite pipe life prediction method which is used for solving the technical problems of huge workload, long test period and uncontrollable effective data in the test process when the flexible composite pipe life is predicted in the prior art.
In order to achieve the above purpose, the invention is realized by adopting the following technical scheme:
the invention discloses a full-size nonmetal reinforced flexible composite pipe life prediction method, which comprises the following steps:
s1: intercepting a test sample on a pipe section of a full-size nonmetal reinforced flexible composite pipe, and processing the test sample into a standard sample;
s2: under the room temperature condition, carrying out a soaking pressing explosion test on the standard sample to obtain the ultimate bearing strength P of the standard sample at room temperature y ；
Then three different test temperatures T are selected 1 、T 2 、T 3 And six test pressures P are selected correspondingly at each test temperature 1 、P 2 、P 3 、P 4 、P 5 、P 6 ；
S3: at three different test temperatures T 1 、T 2 And T 3 And six test pressures P corresponding to each test temperature 1 、P 2 、P 3 、P 4 、P 5 And P 6 As the soaking pressing blasting test conditions, carrying out a soaking pressing blasting test on the standard sample to obtain the failure time t of the standard sample under the corresponding test pressure at three different test temperatures 1 、t 2 、t 3 、t 4 、t 5 、t 6 ；
S4: according to six test pressures P 1 、P 2 、P 3 、P 4 、P 5 、P 6 Time to failure t 1 、t 2 、t 3 、t 4 、t 5 And t 6 Performing linear fitting, and establishing a linear formula of failure time and test pressure at different test temperatures; ultimate bearing strength P of standard sample at room temperature y 50% of the total-size nonmetal reinforced flexible composite pipe is substituted into a linear formula of failure time and test pressure at different test temperatures to obtain the ultimate bearing strength P of the total-size nonmetal reinforced flexible composite pipe at different test temperatures y Failure time t at 50% reduction 501 、t 502 、t 503 ；
S5: according to three different test temperatures T 1 、T 2 And T 3 And t is obtained 501 、t 502 、t 503 Fitting is carried out, and the ultimate bearing strength P of the full-size nonmetal reinforced flexible composite pipe at different test temperatures and the full-size nonmetal reinforced flexible composite pipe is established y Arrhenius formula for reducing failure time by 50%;
s6: when the actual working temperature of the full-size non-metal reinforced flexible composite pipe is T, substituting the actual working temperature T into Arrhenii Wu Sigong obtained in S5 to predict the service life of the full-size non-metal reinforced flexible composite pipe.
Further, in S1, the standard sample meets the requirements of a hydraulic burst test and a hydrostatic test.
Further, in S2, the three different test temperatures T 1 、T 2 And T 3 Sequentially increasing by T 2 Ratio T 1 15 ℃ of greater T 3 Ratio T 2 15℃greater. .
Further, the T is 1 、T 2 And T 3 60 ℃, 75 ℃ and 90 ℃, respectively.
Further, in S2, the test pressure P 1 、P 2 、P 3 、P 4 、P 5 、P 6 Is selected from the ultimate bearing strength P of a standard sample at room temperature y As a reference; the P is 1 、P 2 、P 3 、P 4 、P 5 、P 6 Ultimate bearing strength P greater than that of standard sample at room temperature y And P is one third of 1 、P 2 、P 3 、P 4 、P 5 、P 6 With a logarithmic relationship between them.
Further, the lining of the full-size nonmetal reinforced flexible composite pipe is high-density polyethylene or crosslinked polyethylene, and the reinforcing layer is polyester fiber.
Further, in S4, the linear formula of the failure time and the test pressure at the different test temperatures is:
Y＝10 [alog10(X)+b] ；
wherein Y represents a test pressure, and X represents the failure time of a standard sample under the test pressure; a. b is a constant.
Further, in S5, the temperature T is determined according to three different test temperatures 1 、T 2 And T 3 And t is obtained 501 、t 502 、t 503 The fitting mode is to fit by adopting an exponential function to obtain the ultimate bearing strength P of the full-size nonmetal reinforced flexible composite pipe at different temperatures y Arrhenius formula for failure time at 50% reduction.
Further, the full-size nonmetal reinforced flexible composite pipe has the ultimate bearing strength P at different test temperatures and the full-size nonmetal reinforced flexible composite pipe y The Arrhenius equation for the failure time at 50% reduction is:
wherein T represents different test temperatures, and T represents the ultimate bearing strength P of a nonmetallic tube for the full-size oil-gas field environment y The failure time at 50% reduction; y is 0 、A 1 And t 1 Is constant.
Further, in S4, according to six test pressures P 1 、P 2 、P 3 、P 4 、P 5 And P 6 Time t of failure of the obtained pipe 1 、t 2 、t 3 、t 4 、t 5 And t 6 And (5) carrying out logarithmic linear fitting, and establishing linear formulas of different test temperatures and test pressures.
Compared with the prior art, the invention has the following beneficial effects:
the invention discloses a life prediction method of a full-size nonmetal reinforced flexible composite pipe, which comprises the steps of placing the full-size nonmetal reinforced flexible composite pipe in an environment simulating an oil and gas conveying working condition by using a hydrostatic testing machine and a constant-temperature water tank, and acquiring pipe failure time under each pressure value by selecting specific 6 pressures under each temperature condition under 3 temperature conditions respectively. According to the corresponding relation between the pressure and time, tubing failure time and pressure curves under 3 different temperature conditions and corresponding linear equations are made, 50% of the ultimate bearing strength of a non-metal tube for a full-size oil-gas field environment is substituted into the 3 linear equations to obtain corresponding time, and finally, a non-metal reinforced composite tube temperature-time Arrhenius relation diagram is built, so that the service life of the tubing at a specific temperature can be accurately predicted. The method disclosed by the invention comprehensively considers the overall situation of the nonmetal pipe for the full-size oil-gas field environment, innovatively establishes a full-size temperature-increasing test method to develop a life prediction evaluation method, and enables the evaluation result to be more accurate. The method fully considers the actual running state in the oil-gas environment, and innovatively establishes a temperature-increasing test method based on an Arrhenius equation aiming at the long-term safe service application background of the flexible composite pipe. A relatively harsh indoor acceleration test method is established, and the influence rule of different temperatures on the performance of the device is obtained through the relation between the pressure at different temperatures and the failure time. Secondly, the invention firstly researches and clarifies the influence of the temperature on the service time of the nonmetal pipe for the full-size oil-gas field environment, clarifies the long-term service life of the pipe at different temperatures, and provides basic support for the long-term safety application of the nonmetal pipe for the full-size oil-gas field environment.
Drawings
FIG. 1 is a graph of test pressure versus time for tubing failure at 60 ℃;
FIG. 2 is a graph of test pressure versus time for tubing failure at 75 ℃;
FIG. 3 is a graph of test pressure versus time for tubing failure at 90 ℃;
FIG. 4 is a graph of Arrhenius relationship between temperature and time for a non-metallic tube test for a full-scale oil and gas field environment.
Detailed Description
So that those skilled in the art can appreciate the features and effects of the present invention, a general description and definition of the terms and expressions set forth in the specification and claims follows. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, and in the event of a conflict, the present specification shall control.
The theory or mechanism described and disclosed herein, whether right or wrong, is not meant to limit the scope of the invention in any way, i.e., the present disclosure may be practiced without limitation to any particular theory or mechanism.
All features such as values, amounts, and concentrations that are defined herein in the numerical or percent ranges are for brevity and convenience only. Accordingly, the description of a numerical range or percentage range should be considered to cover and specifically disclose all possible sub-ranges and individual values (including integers and fractions) within the range.
Herein, unless otherwise indicated, "comprising," "including," "having," or similar terms encompass the meanings of "consisting of … …" and "consisting essentially of … …," e.g., "a includes a" encompasses the meanings of "a includes a and the other and" a includes a only.
In this context, not all possible combinations of the individual technical features in the individual embodiments or examples are described in order to simplify the description. Accordingly, as long as there is no contradiction between the combinations of these technical features, any combination of the technical features in the respective embodiments or examples is possible, and all possible combinations should be considered as being within the scope of the present specification.
The invention provides a life prediction method of a full-size nonmetal reinforced flexible composite pipe with improved temperature, which comprises the following steps:
s1: sample preparation
Intercepting a test sample from a flexible composite pipe section, processing the test sample into a standard sample conforming to a hydraulic blasting and hydrostatic test, and adjusting the state of the sample according to standard requirements;
s2: test condition determination
1) Test temperature: the invention adopts an elevated temperature calculation method to determine 3 different temperaturesDegree (T) 1 、T 2 And T 3 ) The interval between 3 temperature points is 15 ℃, according to nonmetal reinforced flexible composite pipe characteristic (the inner liner is high density polyethylene or crosslinked polyethylene, the reinforcing layer is polyester fiber), three temperature points are respectively 60 ℃, 75 ℃ and 90 ℃ (the temperature is determined according to the long-term service highest temperature of the inner liner material), the default inner liner is a relatively common high density polyethylene or crosslinked polyethylene material, the long-term service temperature is not higher than 65 ℃ and 75 ℃, and for other thermoplastics as inner liners such as PVDF and the like, three higher temperature points can be selected according to practical conditions.
2) Test pressure:
(1) the method comprises the following steps At three different test temperatures T 1 、T 2 And T 3 Carrying out a soaking pressing blasting test on the standard sample to respectively obtain the ultimate bearing strength P of the standard sample at three test temperatures y1 、P y2 、P y3 ；
(2) Ultimate bearing strength P of standard sample at three test temperatures y1 、P y2 、P y3 For reference, 6 test pressures (P 1 、P 2 、P 3 、P 4 、P 5 And P 6 )。
S3: performance testing
At three different test temperatures T 1 、T 2 And T 3 And six test pressures P for each temperature 1 、P 2 、P 3 、P 4 、P 5 And P 6 As a submerged-compression blasting test condition, a submerged-compression blasting test was performed on a standard sample to obtain a time (t) for tube failure under a corresponding pressure condition 1 、t 2 、t 3 、t 4 、t 5 And t 6 )。
S4: establishing a linear equation
According to six test pressures P 1 、P 2 、P 3 、P 4 、P 5 And P 6 Time t of failure of the resulting tubing 1 、t 2 、t 3 、t 4 、t 5 And t 6 Performing linear fitting, and establishing linear formulas of test pressure and different temperatures; ultimate bearing strength P of standard sample at room temperature y Respectively substituting 50% of the values of the two to obtain the time of pipe failure at corresponding temperature and the linear formula of test pressure to obtain the ultimate bearing strength P of the full-size nonmetal reinforced flexible composite pipe at different temperatures y Failure time t at 50% reduction 501 、t 502 、t 503 The method comprises the steps of carrying out a first treatment on the surface of the According to three different test temperatures T 1 、T 2 And T 3 And t is obtained 501 、t 502 、t 503 Fitting to establish the ultimate bearing strength P of the nonmetallic tube for the full-size oil-gas field environment at different temperatures y Arrhenius formula for 50% reduction in time to failure;
when the actual working temperature of the nonmetal pipe for the full-size oil-gas field environment is T, the actual working temperature is T, and the T is substituted into Arrhenii Wu Sigong in S5 to predict the service life of the full-size nonmetal reinforced flexible composite pipe.
(1) At a temperature T 1 Log linear fit of pressure to time to failure under conditions:
table 2T 1 Corresponding failure time under different test pressures
Log-linear fitting was performed on the two sets of data in table 2, time to failure (h) and test pressure (MPa), to obtain T 1 Mathematical equation (formula 1) of test pressure and failure time of nonmetallic reinforced flexible composite pipe under the condition:
Y＝10 [a1log10(X)+b1] (1)
wherein: test pressure of Y-nonmetal reinforced flexible composite pipe
X-failure time of non-metallic reinforced flexible composite pipe under such pressure conditions
At temperature T 1 Under the condition that the pressure of the nonmetal reinforced flexible composite pipe reaches 50 percent of the threshold value (namely the ultimate bearing strength P) y 50%,1/2*P of y MPa), substituting formula (1) to obtain the corresponding exposure time X of t 1 h(t 1 Day/24, t 1 /8760 years).
(2) At a temperature T 2 Log linear fit of pressure to time to failure under conditions:
table 3T 2 Corresponding failure time under different test pressures
| Test pressure (MPa) | Time to failure (h) |
| P 21 | t 21 |
| P 22 | t 22 |
| P 23 | t 23 |
| P 24 | t 24 |
| P 25 | t 25 |
| P 26 | t 26 |
The two sets of data, failure time (h) and test pressure (MPa) in Table 3, were log-linearly fitted to give T 2 Mathematical equation of test pressure and failure time of nonmetallic reinforced flexible composite pipe under the condition (formula 2):
Y＝10 [a2log10(X)+b2] (2)
wherein:
y-nonmetal reinforced flexible composite pipe test pressure
X-time to failure under such pressure conditions
At temperature T 2 Under the condition that the pressure of the nonmetal reinforced flexible composite pipe reaches 50 percent of the threshold value (namely the ultimate bearing strength P) y 50%,1/2*P of y MPa), substituting formula (2) to obtain the corresponding exposure time X of t 2 h(t 2 Day/24, t 2 /8760 years).
(3) At a temperature T 3 Log linear fit of pressure to time to failure under conditions:
table 4T 3 Corresponding failure time under different test pressures
| Test pressure (MPa) | Time to failure (h) |
| P 31 | t 31 |
| P 32 | t 32 |
| P 33 | t 33 |
| P 34 | t 34 |
| P 35 | t 35 |
| P 36 | t 36 |
The two sets of data, failure time (h) and test pressure (MPa) in Table 4, were log-linearly fitted to give T 1 Mathematical equation (formula 1) of test pressure and failure time of nonmetallic reinforced flexible composite pipe under the condition:
Y＝10 [a3log10(X)+b3] (3)
wherein:
y-nonmetal reinforced flexible composite pipe test pressure
X-time to failure under such pressure conditions
At temperature T 3 Under the condition that the pressure of the nonmetal reinforced flexible composite pipe reaches 50 percent of the threshold value (namely, the test pressure of a sample is 50 percent of the normal-temperature limit bearing pressure, 1/2*P) y MPa), substituting formula (3) to obtain the corresponding exposure time X of t 3 h(t 3 Day/24, t 3 /8760 years).
(4) Establishing an Arrhenius equation
Ultimate bearing strength P of standard sample at three test temperatures y Respectively substituting 50% of the values of the non-full-size non-metal reinforced flexible composite pipe at different temperatures into the obtained linear formulas of the pipe failure time and test pressure at corresponding temperatures to obtain the ultimate bearing strength P of the non-full-size non-metal reinforced flexible composite pipe at different temperatures y Failure time t at 50% reduction 501 、t 502 、t 503 The corresponding parameters are shown in Table 5.
TABLE 5 time-temperature parameters at different simulated temperatures
| Type(s) | Simulated temperature 1 | Simulated temperature 2 | Simulated temperature 3 |
| T(℃) | T 1 | T 2 | T 3 |
| T(K) | T 1 +273 | T 2 +273 | T 3 +273 |
| 1/T(K) | 1/(T 1 +273) | 1/(T 2 +273) | 1/(T 3 +273) |
| t 50 (h) | t 501 | t 502 | t 503 |
| ln(1/t) | ln(1/t 501 ) | ln(1/t 502 ) | ln(1/t 503 ) |
Test temperature 1/T (K) and time ln (1/T) (h) in Table 5, and fitting the two sets of data by using an exponential function to obtain a nonmetallic reinforced flexible composite pipe temperature-time (formula 4):
ln(1/t)＝y 0 +A 1 *exp(-1/T/t 1 ) (4)
wherein:
t-temperature (K)
t-time (h) corresponding to failure pressure reaching 50% of threshold
Wherein y0, A1 and t 1 Is constant.
S5: lifetime estimation:
when the service temperature of the pipe is known to be T, substituting the service temperature into the formula (4), and calculating to obtain the service life T corresponding to the temperature.
Because the test medium is pure water, the service life needs to be reduced according to different conveying mediums: t' =t×f f
a) F when delivering gas f A value of not more than 0.67;
b) F when transporting liquid hydrocarbons and multiphase fluids f A value of not more than 0.8;
c) F when delivering water f The value is not greater than 1.0.
The invention will be further illustrated with reference to specific examples. It is to be understood that these examples are illustrative of the present invention and are not intended to limit the scope of the present invention. Further, it is understood that various changes and modifications may be made by those skilled in the art after reading the teachings of the present invention, and such equivalents are intended to fall within the scope of the claims appended hereto.
The following examples use instrumentation conventional in the art. The experimental methods, in which specific conditions are not noted in the following examples, are generally conducted under conventional conditions or under conditions recommended by the manufacturer. The following examples used various starting materials, unless otherwise indicated, were conventional commercial products, the specifications of which are conventional in the art. In the description of the present invention and the following examples, "%" means weight percent, and "parts" means parts by weight, and ratios means weight ratio, unless otherwise specified.
Example 1
The service life prediction method for the nonmetal reinforced flexible composite pipe with the specification of DN100mm PN8 MPa comprises the following steps:
1) Acquiring the limit bearing capacity P=32 MPa under normal temperature by adopting a hydrostatic testing machine;
2) A log-linear fit of the pressure at 60 ℃ and time to failure was performed:
TABLE 6 corresponding failure times at 60℃under different test pressures
| Test pressure (MPa) | Time to failure (h) |
| 26 | 10 |
| 24 | 80 |
| 22 | 500 |
| 20 | 3000 |
| 19 | 8000 |
| 18.5 | 10000 |
The two sets of data in table 6, time to failure (h) and test pressure (MPa), were log-linearly fitted as shown in fig. 1 to obtain a mathematical equation of test pressure versus time to failure for a nonmetallic reinforced flexible composite tube at 60 ℃ (equation 5):
Y＝10 [-0.04898log10(X)+1.4694] (5)
wherein:
test pressure of Y-nonmetal reinforced flexible composite pipe
X-failure time of non-metallic reinforced flexible composite pipe under such pressure conditions
When the pressure of the nonmetal reinforced flexible composite pipe reaches 50% of the threshold value (the test pressure of a sample is 50% of the normal temperature limit bearing pressure, namely 16 MPa) at the temperature of 60 ℃, the corresponding exposure time X is 260615h (10859 days, 29.75 years) after substituting into the formula (5).
3) A log linear fit of the pressure at 75 ℃ and time to failure was performed:
TABLE 7 corresponding failure times at 75℃under different test pressures
| Test pressure (MPa) | Time to failure (h) |
| 27 | 10 |
| 22 | 500 |
| 20.5 | 1000 |
| 19.5 | 3000 |
| 19 | 6000 |
| 18.5 | 10000 |
The two sets of data in table 7, time to failure (h) and test pressure (MPa), were log-linearly fitted as shown in fig. 2 to obtain a mathematical equation of test pressure versus time to failure for a non-metallic reinforced flexible composite tube at 75 ℃ (equation 6):
Y＝10 [-0.05245log10(X)+1.46461] (6)
wherein:
y-nonmetal reinforced flexible composite pipe test pressure
X-time to failure under such pressure conditions
When the pressure of the nonmetal reinforced flexible composite pipe reaches 50% of the threshold value (the test pressure of a sample is 50% of the normal temperature limit bearing pressure, namely 16 MPa) at the temperature of 75 ℃, the corresponding exposure time X is 92564.6h (3856.8 days, 10.56 years) after substituting into the formula (6).
4) A log linear fit of the pressure at 90 ℃ and time to failure was performed:
TABLE 8 corresponding failure times at 90℃under different test pressures
The two sets of data in table 8, time to failure (h) and test pressure (MPa), were log-linearly fitted as shown in fig. 3 to obtain a mathematical equation of test pressure versus time to failure for a non-metallic reinforced flexible composite pipe at 90 ℃ (equation 7):
Y＝10 [-0.0658log10(X)+1.47414] (7)
wherein:
y-nonmetal reinforced flexible composite pipe test pressure
X-time to failure under such pressure conditions
When the pressure of the nonmetal reinforced flexible composite pipe reaches 50% of the threshold value (the test pressure of a sample is 50% of the normal temperature limit bearing pressure, namely 16 MPa) at the temperature of 90 ℃, the corresponding exposure time X is 12695.45h (529 days, 1.45 years) after substituting into the formula (7).
5) Establishing an Arrhenius equation
T 1 、T 2 And T 3 Test time t when failure pressure P of nonmetal reinforced flexible composite pipe is reduced by 50 percent under condition 50 The corresponding parameters are shown in Table 9.
TABLE 9 time-temperature parameters at different simulated temperatures
| Type(s) | Simulated temperature 1 | Simulated temperature 2 | Simulated temperature 3 |
| T(℃) | 60 | 75 | 90 |
| T(K) | 333 | 348 | 363 |
| 1/T(K) | 0.003003 | 0.002874 | 0.002755 |
| t 50 (h) | 260615 | 92564.6 | 12695.45 |
| ln(1/t) | -12.47 | -11.44 | -9.45 |
The test temperature 1/T (K) and time ln (1/T) (h) data in table 9 were fitted using an exponential function, as shown in fig. 4, to obtain a nonmetallic-reinforced flexible composite tube temperature-time arrhenius formula (8):
ln(1/t)＝-13.36178+53158300*exp(-1/T/0.000167734) (8)
wherein:
t-temperature (K)
t-time (h) corresponding to failure pressure reaching 50% of threshold
6) Lifetime estimation:
substituting different service temperatures of the pipe into the formula (8) to obtain service years corresponding to the pipe at different temperatures under the working conditions of the clean water environment of the oilfield site, wherein the service years are shown in the table 10.
TABLE 10 service life at different temperatures and medium conditions
Because the test medium is pure water, service life needs to be reduced according to different conveying mediums, and service life under different medium environments can be further obtained by introducing medium correction coefficients according to different conveying mediums, as shown in Table 11.
a) 0.9 of oilfield sewage is conveyed;
b) A reduction factor of 0.8 when transporting liquid hydrocarbon and multiphase fluid;
c) The reduction coefficient is 0.67 when the gas is conveyed;
the reduction coefficient is 0.81 when the high-pressure sulfur-containing gas medium is conveyed.
d) If the superposition condition of various working conditions is met, the superposition treatment can be carried out by considering the reduction coefficient, so that the long-term safe service is ensured.
TABLE 11 service life at different temperatures and medium conditions
The non-metal reinforced flexible composite pipe in the embodiment is replaced by a non-metal pipe for the full-size oil-gas field environment, including a metal reinforced flexible composite pipe, a glass fiber reinforced plastic pipe, a PE pipe, a plastic alloy pipe and the like, and the service life of the non-metal pipe can be predicted by adopting the method disclosed by the invention.
The above is only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited by this, and any modification made on the basis of the technical scheme according to the technical idea of the present invention falls within the protection scope of the claims of the present invention.
Claims (10)
1. The full-size nonmetal reinforced flexible composite pipe life prediction method is characterized by comprising the following steps of:
s1: intercepting a test sample on a pipe section of a full-size nonmetal reinforced flexible composite pipe, and processing the test sample into a standard sample;
s2: under the room temperature condition, carrying out a soaking pressing explosion test on the standard sample to obtain the ultimate bearing strength P of the standard sample at room temperature y ；
Then three different test temperatures T are selected 1 、T 2 、T 3 And six test pressures P are selected correspondingly at each test temperature 1 、P 2 、P 3 、P 4 、P 5 、P 6 ；
S3: at three different test temperatures T 1 、T 2 And T 3 And six test pressures P corresponding to each test temperature 1 、P 2 、P 3 、P 4 、P 5 And P 6 As the soaking pressing blasting test conditions, carrying out a soaking pressing blasting test on the standard sample to obtain the failure time t of the standard sample under the corresponding test pressure at three different test temperatures 1 、t 2 、t 3 、t 4 、t 5 、t 6 ；
S4: according to six test pressures P 1 、P 2 、P 3 、P 4 、P 5 、P 6 Time to failure t 1 、t 2 、t 3 、t 4 、t 5 And t 6 Performing linear fitting, and establishing a linear formula of failure time and test pressure at different test temperatures; ultimate bearing strength P of standard sample at room temperature y 50% of the total-size nonmetal reinforced flexible composite pipe is substituted into a linear formula of failure time and test pressure at different test temperatures to obtain the ultimate bearing strength P of the total-size nonmetal reinforced flexible composite pipe at different test temperatures y Failure time t at 50% reduction 501 、t 502 、t 503 ；
S5: according to three different test temperatures T 1 、T 2 And T 3 And t is obtained 501 、t 502 、t 503 Fitting to build the full-size nonmetal reinforced flexible composite pipe under different test temperatures and full-size nonmetal reinforced flexibilityUltimate bearing strength P of sexual composite pipe y Arrhenius formula for reducing failure time by 50%;
s6: when the actual working temperature of the full-size non-metal reinforced flexible composite pipe is T, substituting the actual working temperature T into Arrhenii Wu Sigong obtained in S5 to predict the service life of the full-size non-metal reinforced flexible composite pipe.
2. The method for predicting the service life of the full-size nonmetal reinforced flexible composite pipe according to claim 1, wherein in S1, the standard sample meets the requirements of a hydraulic burst test and a hydrostatic test.
3. The method for predicting the service life of a full-size nonmetal reinforced flexible composite pipe as claimed in claim 1, wherein in S2, the three different test temperatures T 1 、T 2 And T 3 Sequentially increasing by T 2 Ratio T 1 15 ℃ of greater T 3 Ratio T 2 15℃greater.
4. A method for predicting the life of a full-size non-metallic reinforced flexible composite pipe as claimed in claim 3, wherein said T is 1 、T 2 And T 3 60 ℃, 75 ℃ and 90 ℃, respectively.
5. The method for predicting the service life of a full-size nonmetal reinforced flexible composite pipe according to claim 1, wherein in S2, the test pressure P is 1 、P 2 、P 3 、P 4 、P 5 、P 6 Is selected from the ultimate bearing strength P of a standard sample at room temperature y As a reference; the P is 1 、P 2 、P 3 、P 4 、P 5 、P 6 Ultimate bearing strength P greater than that of standard sample at room temperature y And P is one third of 1 、P 2 、P 3 、P 4 、P 5 、P 6 With a logarithmic relationship between them.
6. The method for predicting the service life of a full-size nonmetal reinforced flexible composite pipe according to claim 1, wherein the lining of the full-size nonmetal reinforced flexible composite pipe is high-density polyethylene or crosslinked polyethylene, and the reinforcing layer is polyester fiber.
7. The method for predicting the service life of a full-size nonmetal reinforced flexible composite pipe according to claim 1, wherein in S4, the linear formulas of the failure time and the test pressure at different test temperatures are as follows:
Y＝10 [alog10(X)+b] ；
wherein Y represents a test pressure, and X represents the failure time of a standard sample under the test pressure; a. b is a constant.
8. The method for predicting the service life of a full-size nonmetal reinforced flexible composite pipe according to claim 1, wherein in S5, the service life is predicted according to three different test temperatures T 1 、T 2 And T 3 And t is obtained 501 、t 502 、t 503 The fitting mode is to fit by adopting an exponential function to obtain the ultimate bearing strength P of the full-size nonmetal reinforced flexible composite pipe at different temperatures y Arrhenius formula for failure time at 50% reduction.
9. The method for predicting the service life of a full-size non-metal reinforced flexible composite pipe according to claim 8, wherein the full-size non-metal reinforced flexible composite pipe has ultimate bearing strength P at different test temperatures and full-size non-metal reinforced flexible composite pipe y The Arrhenius equation for the failure time at 50% reduction is:
wherein T represents different testsTemperature, t, represents the ultimate bearing strength P of a nonmetallic tube for a full-size oil-gas field environment y The failure time at 50% reduction; y is 0 、A 1 And t 1 Is constant.
10. The method for predicting the service life of a full-size nonmetal reinforced flexible composite pipe according to claim 1, wherein in S4, according to six test pressures P 1 、P 2 、P 3 、P 4 、P 5 And P 6 Time t of failure of the obtained pipe 1 、t 2 、t 3 、t 4 、t 5 And t 6 And (5) carrying out logarithmic linear fitting, and establishing linear formulas of different test temperatures and test pressures.
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