Sleeve testing device and strength checking and correcting method

Abstract

The invention provides a sleeve testing device and a strength checking and correcting method, and relates to the technical field of offshore high temperature and high pressure, and the device comprises a temperature control system which is used for providing a steady-state high-temperature simulation environment and a transient high-temperature simulation environment for a sleeve sample; the loading system is used for applying axial, radial and internal loads to the casing sample; the monitoring system is used for monitoring a surface temperature field, inner wall strain and leakage of the casing sample; and the data processing and control unit is respectively connected with the temperature control system, the loading system and the monitoring system. The method adopts the device and comprises the following steps: selecting a casing sample, fixing a sensor and completing initial calibration; heating the whole casing pipe and keeping the temperature constant, and applying instantaneous thermal shock to a specific area; synchronously applying axial, radial and internal loads; cooperatively monitoring the temperature field, the strain and the leakage rate to form an associated database; and correcting the safety coefficient. The invention solves the problems of single test temperature and insufficient load coupling of the traditional casing, and is suitable for casing performance evaluation.

Description

TECHNICAL FIELD

[0001] The present application relates to the offshore high temperature and high pressure technical field, and particularly relates to a casing testing device and a strength checking correction method. BACKGROUND

[0002] The performance test of casing under high temperature environment is crucial to engineering safety, and the current common test methods include:

[0003] Static high temperature test: using resistance furnace or muffle furnace heating to test the mechanical properties of the material under constant high temperature;

[0004] Induction heating local test: rapidly heating local area through electromagnetic induction to simulate thermal shock;

[0005] Sealing test: applying internal pressure under high temperature to detect the leakage rate.

[0006] The present applicant finds that the prior art at least has the following technical problems:

[0007] 1. The conventional resistance furnace has slow heating, and cannot simulate the rapid temperature change of downhole or reactor;

[0008] 2. Most devices can only apply axial pressure or internal pressure alone, and it is difficult to simulate real working conditions and the data accuracy is low;

[0009] 3. The conventional strain gauge is easy to fail under high temperature, the sealing detection sensitivity is insufficient, and the yield strength and tensile strength of the casing under high temperature have attenuation effect.

[0010] Therefore, there is an urgent need for a casing testing device and a strength checking correction method to solve the above technical problems SUMMARY

[0011] The present application aims to provide a casing testing device and a strength checking correction method, which solves the problems of single temperature and insufficient load coupling of the conventional device, and is suitable for performance evaluation of full-size casing of API / ISO standardization. The technical effects produced by the preferred technical solutions in the technical solutions provided by the present application are described in detail below.

[0012] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0013] The present application provides a casing testing device, which comprises:

[0014] A temperature control system for providing a steady-state high temperature simulation environment and a transient high temperature simulation environment for the casing sample;

[0015] A loading system for applying axial, radial and internal load to the casing sample;

[0016] A monitoring system for monitoring the surface temperature field of the sleeve sample, the strain of the inner wall of the sleeve sample, and the leakage of the sleeve sample;

[0017] A data processing and control unit connected with the temperature control system, the loading system, and the monitoring system respectively.

[0018] Preferably, the temperature control system comprises:

[0019] A partition temperature control resistance furnace for providing a steady-state high-temperature ring mirror for the sleeve sample, comprising a main body, and a heating cavity arranged inside the main body;

[0020] An induction heating coil nested in the heating cavity, and the induction heating coil coincides with the axis of the heating cavity.

[0021] Preferably, the loading system comprises:

[0022] Two groups of axial hydraulic cylinders symmetrically arranged at both ends of the sleeve sample, and the piston rods of the axial hydraulic cylinders are coaxially connected with the high-temperature-resistant sealing joints at the ends of the sleeve sample, and the axial hydraulic cylinders are used for applying axial load to the sleeve sample.

[0023] A radial pressure bag wrapped around the outer wall of the sleeve sample for applying radial load to the sleeve sample.

[0024] An internal pressure pump connected with the inner cavity of the sleeve sample through a pipeline for applying internal load to the sleeve sample.

[0025] Preferably, the monitoring system comprises:

[0026] An infrared thermal imager arranged on the surface of the partition temperature control resistance furnace for monitoring the surface temperature field of the sleeve sample.

[0027] A fiber Bragg grating sensor fixed on the inner wall of the sleeve sample for measuring the strain of the inner wall of the sleeve sample.

[0028] A helium mass spectrometer leak detector connected with the sealing interface of the sleeve sample through a pipeline for detecting the leakage of the sleeve sample.

[0029] Preferably, the fiber Bragg grating sensors are equidistantly arranged along the axial direction of the sleeve sample, and multiple measuring points are uniformly distributed around each cross section of the sleeve sample.

[0030] The lead wires of the fiber Bragg grating sensors are led out through the high-temperature-resistant sealing joints at the ends of the sleeve sample.

[0031] Preferably, a temperature sensor is arranged on the inner wall of the partition temperature control resistance furnace, and the temperature sensor is connected with the data processing and control unit.

[0032] A pressure sensor is mounted on the outside of the radial pressure bag, and the pressure sensor is connected to the data processing and control unit.

[0033] Preferably, the data processing and control unit comprises a data receiver, a data converter and a terminal device, wherein:

[0034] The temperature sensor and the pressure sensor are connected to the data receiver through data lines;

[0035] The data receiver is in communication connection with the terminal device through the data converter.

[0036] A casing strength checking correction method, using the casing test device described above, comprising the following steps:

[0037] S1: Select a casing sample, fix the sensor and complete the initial calibration;

[0038] S2: Heat the whole casing sample by the temperature control system and keep constant temperature, and then apply transient thermal shock to the specific area;

[0039] S3: Apply axial, radial and internal load synchronously through the loading system;

[0040] S4: Monitor the temperature field, strain and leakage rate by the sensor, and form a correlation database;

[0041] S5: Correct the safety factor based on the measured high-temperature and normal-temperature yield strength ratio, and complete the performance checking of the casing sample.

[0042] Preferably, the length size of the casing sample is 1.5 times or more than the diameter size, and the sensor comprises an infrared thermal imager, a fiber grating sensor and a helium mass spectrometric leak detector.

[0043] Preferably, the safety factor correction rule is:

[0044] When the high-temperature and normal-temperature yield strength ratio Kσ(T)≤0.95, take the upper limit value;

[0045] When the high-temperature and normal-temperature yield strength ratio 0.95<Kσ(T)<1.05, take the middle value;

[0046] When the high-temperature and normal-temperature yield strength ratio Kσ(T)≥1.05, take the lower limit value.

[0047] The casing test device provided by the application can simulate high temperature, high pressure and complex load coupling conditions by a composite temperature control system for providing a steady-state high temperature simulation environment and a transient high temperature simulation environment for a casing sample, a multi-axis loading system for applying axial, radial and internal loads to the casing sample, and an intelligent detection system for monitoring the surface temperature field of the casing sample, the strain of the inner wall of the casing sample and the leakage of the casing sample.

[0048] The casing strength checking correction method provided by the application realizes accurate testing of the casing's anti-collapse, sealing and thermal fatigue performance by dynamic temperature control and synchronous application of multiple loads, and the safety factor of the casing's checking result is corrected according to the ratio of the measured high-temperature yield strength to the normal-temperature strength with reference to the national standard. The problems of single temperature and insufficient load coupling in the traditional casing performance evaluation are solved, and the casing performance evaluation is suitable for API / ISO standardization. BRIEF DESCRIPTION OF DRAWINGS

[0049] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0050] Figure 1 is a structural schematic diagram of an embodiment of the casing test device of the present application;

[0051] Figure 2 is a flowchart of the casing strength checking correction method of the present application.

[0052] In the figure: 1, partition temperature control resistance furnace; 2, induction heating coil; 3, axial hydraulic cylinder; 4, radial pressure bag; 5, control valve; 6, internal pressure pump; 7, infrared thermal imager; 8, fiber Bragg grating sensor; 9, helium mass spectrometric leak detector; 10, main body; 11, heating cavity; 12, data converter; 13, terminal device; 14, temperature sensor; 15, pressure sensor; 16, data receiver; 100, casing sample. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solutions and advantages of the present application more clear, the technical solutions of the present application will be described in detail below. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0054] In the description of the present application, it needs to be understood that the orientation or positional relationship indicated by the terms "center", "lateral", "length", "width", "height", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "side" and the like is based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0055] In the description of the present application, it also needs to be explained that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0056] Figure 1 is a structural schematic diagram of the embodiment, as Figure 1 shown, the present embodiment provides a casing test device, which comprises a temperature control system, a loading system, a monitoring system and a data processing and control unit.

[0057] The temperature control system is used to provide a steady-state high-temperature simulation environment and a transient high-temperature simulation environment for the casing sample 100. The temperature control system in the present embodiment is the key to realize high-temperature environment simulation, which provides two kinds of high-temperature environments of steady state and transient state to simulate the heating condition of the casing under different working conditions.

[0058] The loading system is used to apply axial, radial and internal load to the casing sample 100. By applying load to the casing sample 100 from three directions of axial, radial and internal, the force borne by the casing in actual work is comprehensively simulated.

[0059] The monitoring system is used to monitor the surface temperature field of the casing sample 100, the strain of the inner wall of the casing sample 100 and the leakage of the casing sample 100. By setting the monitoring system to monitor the surface temperature field, the inner wall strain and the leakage condition of the casing sample 100, the key performance parameters of the casing sample 100 in the test process are obtained.

[0060] The data processing and control unit is connected with the temperature control system, the loading system and the monitoring system respectively, and realizes the coordinated control of each system and the processing and analysis of data.

[0061] The casing test device can comprehensively and accurately simulate the stress and heat conditions of the casing in the actual working environment through the cooperative work of the temperature control system, the loading system, the monitoring system and the data processing and control unit, thereby providing a reliable platform for the performance test of the casing. The setting of the data processing and control unit realizes the automatic control of the test process and the real-time processing of data, improves the efficiency and accuracy of the test, and facilitates the in-depth analysis and research of the test data.

[0062] As an optional implementation, the temperature control system in the embodiment includes a partition temperature control resistance furnace 1 and an induction heating coil 2. Specifically, the partition temperature control resistance furnace 1 can withstand a maximum temperature of 1200℃, and can accurately control the temperature through PID, with a temperature difference range of ±5℃. The induction heating coil 2 is used for local rapid heating, with a range set to ≥50℃ / s to simulate thermal shock. Through the cooperation of the partition temperature control resistance furnace 1 and the induction heating coil 2, both steady-state and transient high-temperature simulation are considered.

[0063] Specifically, the partition temperature control resistance furnace 1 is used to provide a steady-state high-temperature environment for the casing sample 100. It includes a main body 10, and a heating cavity 11 is arranged inside the main body 10, which ensures the stability and uniformity of the steady-state high-temperature environment and provides reliable basic temperature conditions for the casing sample 100. Moreover, the partition temperature control design can realize temperature control of different regions in the heating cavity 11 to meet different test requirements.

[0064] The induction heating coil 2 is nested in the heating cavity 11, and the axis of the induction heating coil 2 coincides with that of the heating cavity 11; the casing sample 100 is arranged in the induction heating coil 2 and can penetrate the center of the induction heating coil 2, ensuring the uniformity and accuracy of the induction heating and enabling precise transient thermal shock on the specific region of the casing sample 100. During the test, the casing sample 100 is locally heated by the induction heating coil 2 to realize transient high-temperature simulation, thereby simulating the local high-temperature conditions that the casing may encounter in actual work and improving the authenticity and reliability of the test.

[0065] As an optional implementation, the loading system includes two groups of axial hydraulic cylinders 3, radial pressure bags 4 and internal pressure pumps 6, and the loading system can realize multi-axis synchronous pressure through the loading system, thereby truly restoring the downhole environment.

[0066] The axial hydraulic cylinder 3 is arranged symmetrically at both ends of the casing sample, the piston rod of the axial hydraulic cylinder 3 is coaxially connected with the high-temperature-resistant sealing joint at the end of the casing sample 100, and the axial hydraulic cylinder 3 is used for applying an axial load to the casing sample 100; in the embodiment, the axial hydraulic cylinder 3 is arranged symmetrically at both ends of the casing sample 100, and the piston rod thereof is coaxially connected with the high-temperature-resistant sealing joint at the end of the casing sample 100; in use, the axial load is applied to the casing sample 100 through the extension and retraction of the piston rod, the symmetric arrangement and coaxial connection of the axial hydraulic cylinder ensure the uniformity and stability of the axial load application, and the influence of uneven load application on the test result is avoided.

[0067] The radial pressure bag 4 is wrapped around the outer wall of the casing sample 100 and can be expanded to simulate the downhole confining pressure, with a range of 0-50 MPa, and is used for applying a radial load to the casing sample 100. In use, the radial load can be uniformly applied to the casing sample 100 through the expansion of the pressure bag to simulate the circumferential pressure of the casing on the formation.

[0068] The internal pressure pump 6 is communicated with the inner cavity of the casing sample through a pipeline, a control valve 5 is arranged on the pipeline, and 0-100 MPa helium / nitrogen internal pressure can be provided to apply an internal load to the casing sample. The internal load of the casing sample is precisely applied by injecting the medium into the internal cavity of the casing sample through the control of the control valve 5.

[0069] By arranging the loading system including the axial hydraulic cylinder 3, the radial pressure bag 4 and the internal pressure pump 6, the multi-directional load borne by the casing in actual work is comprehensively simulated, and the bearing capacity of the casing is accurately evaluated.

[0070] As an optional implementation, the monitoring system includes an infrared thermal imager 7, an optical fiber grating sensor 8 and a helium mass spectrometer leak detector 9.

[0071] The infrared thermal imager 7 is arranged on the surface of the partition temperature control resistance furnace 1 and is used for monitoring the surface temperature field of the casing sample in real time; the temperature distribution of the surface of the casing sample can be directly reflected, and the surface temperature field of the casing sample is monitored in real time and comprehensively, so as to provide temperature data for analyzing the performance change of the casing in a high-temperature environment.

[0072] The optical fiber grating sensor 8 can withstand a high temperature of 1000℃ and is fixed on the inner wall of the casing sample and is used for measuring the strain of the inner wall of the casing sample; the deformation of the casing in the stress process can be monitored in real time and accurately, and a key basis for evaluating the structural strength of the casing is provided.

[0073] The helium mass spectrometer leak detector 9 is connected with the sealing interface of the casing sample through a pipeline and is used for detecting the leakage of the casing sample. The sensitivity of the helium mass spectrometer leak detector 9 is 10-9 Pa·m 3 / s, high sensitivity, can detect small leaks in time, ensure the safety and accuracy of the test, but also provides reliable data support for the study of the sealing performance of the casing.

[0074] As an optional implementation, the fiber grating sensors 8 are arranged equidistantly along the axial direction of the casing sample, and multiple measuring points are uniformly distributed in the circumferential direction of each cross section of the casing sample, so that the strain of the casing sample at different positions can be measured comprehensively and accurately

[0075] Specifically, in this embodiment, the array of fiber grating sensors 8 is fixed to the inner wall of the casing, and is arranged equidistantly along the axial direction with a spacing of 50mm±1mm. Four measuring points are uniformly distributed in the circumferential direction of each cross section of the casing sample, so as to obtain the strain distribution of the casing sample 100 in the axial and circumferential directions, and to monitor the uneven deformation. In this way, the stress state of the casing can be comprehensively understood, and the accuracy and comprehensiveness of the strain measurement are improved.

[0076] In this embodiment, the leads of the fiber grating sensors 8 are led out through the high-temperature-resistant sealing joint at the end of the casing sample 100, so as to avoid signal transmission failure in a high-temperature environment, ensure stable signal transmission, and ensure smooth testing.

[0077] As an optional implementation, a temperature sensor 14 is arranged on the inner wall of the partitioned temperature control resistance furnace 1, and the temperature sensor 14 is connected with a data processing and control unit. A pressure sensor 15 is installed on the outer side of the radial pressure bag 4, and the pressure sensor 15 is connected with the data processing and control unit.

[0078] By arranging the temperature sensor on the inner wall of the partitioned temperature control resistance furnace, the temperature in the heating cavity can be monitored in real time, and the temperature signal is transmitted to the data processing and control unit. The pressure sensor is installed on the outer side of the radial pressure bag, which is used to monitor the pressure in the radial pressure bag. The pressure signal is also transmitted to the data processing and control unit, so as to realize real-time monitoring of the temperature of the heating cavity and the pressure of the radial pressure bag, provide accurate feedback information for the data processing and control unit, and facilitate precise control of the temperature control system and the loading system.

[0079] As an optional implementation, the data processing and control unit includes a data receiver 16, a data converter 12 and a terminal device 13.

[0080] The temperature sensor 14 and the pressure sensor 15 are connected with the data receiver 16 through data lines. The data receiver 16 is in communication connection with the terminal device 13 through the data converter 12. The terminal device 13 in this embodiment includes a computer.

[0081] Specifically, the data receiver 16 is responsible for receiving the data transmitted by each sensor, the data converter 12 converts the received data so that it can be recognized and processed by the terminal device 13, and the terminal device 13 is used for analyzing, storing and displaying the data, and controlling each system according to the analysis result, realizing efficient receiving, conversion and processing of the sensor data. The test personnel can intuitively understand the test data and the running state of the equipment, which is convenient for real-time monitoring and adjustment of the test process. Through the analysis and processing of the data, scientific basis can be provided for the performance evaluation of the casing, and reference can be provided for the optimization and improvement of the device.

[0082] Figure 2 is a flowchart of the casing strength checking and correcting method of the embodiment, as shown in Figure 2 The casing strength checking and correcting method of the embodiment also provides a casing testing device, which comprises the following steps:

[0083] S1: selecting a casing sample, fixing a sensor and completing initial calibration;

[0084] S2: heating the whole casing sample 100 by the temperature control system and keeping constant temperature, and then applying a transient thermal shock to a specific area;

[0085] S3: synchronously applying axial, radial and internal loads by the loading system;

[0086] S4: cooperatively monitoring the temperature field, strain and leakage rate by the sensor to form a correlation database;

[0087] S5: correcting the safety factor based on the measured high-temperature and normal-temperature yield strength ratio to complete the performance checking of the casing sample.

[0088] The casing strength checking and correcting method based on the casing testing device can comprehensively and accurately simulate the complex environment of the casing in actual work, and obtain real and reliable test data. Through the establishment of the correlation database and the correction of the safety factor, the result of the casing performance checking is more scientific and reasonable, which provides an important reference for the design, manufacture and use of the casing, and helps to improve the safety and reliability of the casing.

[0089] Specifically, S1, selecting a casing sample, fixing a sensor and completing initial calibration, the specific operation is as follows:

[0090] Select a standard size casing, such as an oil casing according to API 5CT specification, and cut the casing according to the test requirements, usually the length of the casing sample is 1.5 times the diameter size or more to ensure that the end effect does not affect the test result.

[0091] Before the test, if the surface of the casing sample 100 has an oxide layer and oil stains, the sample surface needs to be sandblasted to remove the oxide layer and oil stains, and the cleanliness is required to be Sa2.5 level. Then, acetone is used for ultrasonic cleaning for 10 minutes to eliminate micro-pollutants.

[0092] The sensors in this embodiment include an infrared thermal imager 7, a fiber grating sensor 8, and a helium mass spectrometer leak detector 9, and also include a temperature sensor 14 and a pressure sensor 15. It should be noted that initial strain calibration, i.e., zero point calibration, needs to be performed before the casing sample 100 is installed, to ensure that the test data benchmark is unified.

[0093] S2: The whole casing sample is heated and kept constant by the temperature control system, and then a transient thermal shock is applied to a specific area, which is specifically as follows:

[0094] First, the partition temperature control resistance furnace 1 is used to uniformly heat the whole casing sample 100 to the target temperature of 600℃ at a linear heating rate of 10℃ / min, and keep constant for 1 hour, to ensure that the material reaches a thermal equilibrium state, and the temperature uniformity deviation is ≤±5℃.

[0095] Then, the induction heating coil 2 is started, and a directional transient thermal shock is applied to the weld or specific weak area of the casing sample 100, and the local temperature is rapidly increased to 800℃ within 1 second, and the heating rate is 50℃ / s, to simulate the extreme working condition of the sudden high temperature or the welding heat affected zone under the well.

[0096] S3: Synchronously apply axial, radial and internal loads through the loading system;

[0097] In this embodiment, the axial hydraulic cylinder 3 is used to apply an axial pressure of 4000kN to the casing sample 100, to simulate the actual column load borne by the pipe string under the well; at the same time, the internal pressure pump 6 using helium medium is used to apply a uniform internal pressure of 70MPa to the inner cavity of the casing, to restore the fluid pressure working condition under the well; and the inflatable high-temperature pressure bag installed on the outer wall of the casing sample 100 is used to apply a radial confining pressure of 30MPa, to accurately simulate the restraining effect of the formation confining pressure on the pipe body. The three kinds of loads are synchronously loaded, and the loading rate is controlled to be 5kN / s in the axial direction and 0.5MPa / s in the pressure direction, to ensure that the stress ratio in each direction meets the actual stress state under the well as specified in the standard. All loading processes are monitored in real time by various sensors resistant to 800℃ high temperature.

[0098] If the synchronous loading effect of the three kinds of loads is not obvious, the stress needs to be appropriately increased, to ensure that the stress ratio in each direction meets the actual stress state under the well as specified in the standard.

[0099] S4: Form an associated database by cooperatively monitoring the temperature field, strain and leakage rate through the sensors;

[0100] In this embodiment, the performance of the casing in high temperature environment is accurately monitored through multi-sensor cooperation: the built-in high-temperature-resistant fiber grating sensor 8 monitors the axial / circumferential strain change of the casing in real time at a sampling frequency of 1 kHz, and the measurement accuracy of ±5με is realized through wavelength demodulation technology; the helium mass spectrometer leak detector 9 detects the sealing interface of the casing sample 100 for 30 minutes, and triggers an alarm when the helium concentration exceeds 1x10 -9 Pa·m 3 All data is transmitted to the central processing unit through the data receiver 16, forming a four-dimensional correlation database of time-temperature-strain-leakage rate, providing a quantitative basis for failure analysis.

[0101] The strain distribution of the casing sample 100 under high temperature load is monitored in real time by the fiber grating sensor 8, the optical signal is converted to strain value through wavelength demodulation algorithm, the accuracy is ±1με, and the thermal expansion interference is eliminated by combining with the temperature compensation model; secondly, the surface temperature field data collected by the infrared thermal imager 7 is compared with the temperature control parameters of the partition temperature control resistance furnace 1 / induction heating coil 2, the temperature uniformity is verified through finite element simulation, and the deviation is ≤±5℃; finally, the leakage rate data output by the helium mass spectrometer is analyzed in association with the pressure curve of the internal pressure pump, and the least square method is used to fit the sealing performance degradation model. All data is integrated and processed by computer, providing a quantitative basis for high temperature mechanism evaluation of casing.

[0102] If the surface temperature of the casing sample 100 is not accurate, the infrared thermal imager 7 needs to scan the casing surface temperature field at a frequency of one frame every 10 seconds to generate a two-dimensional thermal distribution map with an accuracy of ±2℃.

[0103] S5: Based on the measured high temperature and normal temperature yield strength ratio, the safety factor is corrected, and the casing performance is checked.

[0104] In this embodiment, based on the high temperature test data, the safety of the casing performance needs to be evaluated in combination with the petroleum engineering specification. According to the national standard, the safety factor of the casing performance checking result is corrected according to the ratio of the measured high temperature yield strength to the normal temperature strength.

[0105] Specifically, after completing the high temperature performance test, the safety of the casing needs to be evaluated according to the national standard. First of all, based on the ratio K σ (T) of the measured high temperature yield strength to the normal temperature strength, the standard safety factor is corrected. The safety factor correction rule is:

[0106] When the ratio Kσ(T) of high temperature yield strength to normal temperature yield strength is ≤0.95, the upper limit value is taken;

[0107] When the ratio Kσ(T) of high temperature yield strength to normal temperature yield strength is 0.95

[0108] When the high-temperature to normal-temperature yield strength ratio Kσ(T)≥1.05, the lower limit value is taken.

[0109] In combination with the temperature grading template, the anti-extrusion, anti-internal pressure and anti-tension performance are checked, and the actual measured value is required to be≥design value×corrected safety factor. For high-temperature deep wells >200℃, T95 / Q125 steel grade is preferred, and the upper limit of the safety factor is taken. The maximum value of the template is directly used for non-API casing. Through quantitative correction and multi-dimensional checking, the safety of the casing under high-temperature complex working conditions is ensured.

[0110] The following will be described in detail taking the standard API specific casing as an example.

[0111] S1: The casing uses API 5CT P110 grade casing, and the specific parameters are: outer diameter 244.5mm, wall thickness 11.05mm, and length 1.5m.

[0112] Six K-type thermocouples for measuring temperature in the range of 0-1200℃ are arranged equidistantly on the outer wall of the casing, and four groups of fiber Bragg grating sensors 8 are arranged axially on the inner wall of the casing, wherein the fiber Bragg grating sensors 8 include FBG with a spacing of 200mm and a temperature resistance of 1000℃. A helium mass spectrometer leak detector 9 is connected to the sealed end of the casing.

[0113] S2: The partition temperature control resistance furnace 1 is heated to 600℃ at a rate of 10℃ / min, and the temperature is kept for 30 minutes to ensure temperature uniformity within±5℃.

[0114] The induction heating coil 2 is activated, and the middle part of the casing sample length of 100mm is rapidly heated to 800℃ at a rate of 50℃ / s, and the heating lasts for 60 seconds.

[0115] S3: A 4000kN load is applied through an axial hydraulic cylinder 3 to simulate the downhole column load, and the loading rate is 50kN / s. Helium is injected through the internal pressure pump 6, and the pressure is gradually increased to 70MPa, which meets the ISO 13679 standard. A 30MPa uniform confining pressure is applied through the radial pressure bag 4 to simulate the formation pressure.

[0116] S4: The thermocouple and the infrared thermal imager 7 synchronously record the temperature distribution to generate a thermal field cloud chart. The fiber Bragg grating sensor 8 monitors the strain in real time, and the equivalent Von Mises stress is calculated through the formula:

[0117]

[0118] The helium mass spectrometer leak detector 9 continuously monitors for 30 minutes, and the leakage rate is≤1×10 -8 Pa·m 3 / s is qualified.

[0119] S5: Real-time monitoring of the strain distribution of the casing sample 100 under high temperature load by the fiber Bragg grating sensor 8, converting the optical signal into strain value through the wavelength demodulation algorithm, with an accuracy of ±1με, and eliminating the thermal expansion interference by combining the temperature compensation model; comparing the surface temperature field data collected by the infrared thermal imager 7 with the temperature control parameters of the partition temperature control resistance furnace 1 / induction heating coil 2, verifying the temperature uniformity through finite element thermal force coupling simulation, with a deviation of ≤±5℃.

[0120] S6: Integrating all data through a computer to provide quantitative basis for casing high temperature mechanism evaluation.

[0121] S7: Based on the basic safety factor requirement in the current national standard, combined with the attenuation law of casing yield strength and tensile strength under high temperature, using a quantitative correction method to form.

[0122] According to the requirements of casing design strength safety factor in the Chinese Petroleum and Natural Gas Industry Standard (such as SY / T 5724-2008):

[0123] Internal pressure safety factor Si: 1.05-1.15

[0124] External extrusion safety factor Sc: 1.00-1.125

[0125] Tensile safety factor St: 1.60-2.00

[0126] This interval is the design recommended range at normal temperature, reflecting the strength reserve requirement under different complexity conditions.

[0127] Under high temperature conditions, such as 100℃-250℃, the yield strength and tensile strength of the casing show a clear downward trend. To reflect this attenuation effect, the "temperature attenuation coefficient" is introduced, defined as follows:

[0128]

[0129] Where σT represents the yield / tensile strength at temperature T; σ(25℃) is the normal temperature reference value.

[0130] Without changing the original standard design idea, the upper limit of the normal temperature recommended safety factor is adjusted by using the attenuation coefficient. The specific method is as follows:

[0131]

[0132] Where:

[0133] S 25 is the normal temperature recommended safety factor (taking the upper limit of the standard recommended interval);

[0134] is the corrected high temperature recommended safety factor.

[0135] But due to engineering acceptability considerations, the actual recommendation should not be increased without limit, so the increased part after correction is set as a flexible upper limit, and the interval between the recommended value and the maximum value is set for design selection.

[0136] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A test device for a bushing, the test device comprising: The application relates to a casing test device. The casing test device comprises a temperature control system, a loading system, a monitoring system and a data processing and control unit. The temperature control system comprises a partitioned temperature control resistance furnace, an induction heating coil and a temperature sensor. The loading system comprises two groups of axial hydraulic cylinders, a radial pressure bag and an internal pressure pump. The monitoring system comprises an infrared thermal imager, a fiber grating sensor and a helium mass spectrometer leak detector.

2. The bushing testing device of claim 1, wherein, The data processing and control unit comprises a data receiver, a data converter and a terminal device. The casing test device comprises the following steps: S1: selecting a casing sample, fixing the sensor and completing initial calibration; 3. The bushing testing apparatus of claim 2, wherein: S2: heating and constant-temperature heating the casing sample as a whole through the temperature control system, and then applying transient heat shock to a specific region; S3: synchronously applying axial, radial and internal loads through the loading system; S4: cooperatively monitoring a temperature field, strain and leakage rate through the sensor to form a correlation database; S5: correcting a safety coefficient based on a measured high-temperature and normal-temperature yield strength ratio to complete performance checking of the casing sample.

4. The bushing testing apparatus of claim 3, wherein: ​ ​ ​ ​ 5. The bushing testing apparatus of claim 4, wherein: ​ ​ 6. The cannula testing device of any of claims 3-5, wherein: ​ ​ 7. The bushing testing device of claim 6, wherein: ​ ​ ​ 8. A method of casing strength calibration correction, characterized by: ​ ​ ​ ​ ​ ​ 9. The method of casing strength calibration correction of claim 8, wherein: The length of the sleeve sample is 1.5 times or more than the diameter, and the sensor comprises an infrared thermal imager, a fiber grating sensor and a helium mass spectrometer leak detector.

10. The method of casing strength calibration correction of claim 9, wherein, The safety factor correction rule is: When the high-temperature and normal-temperature yield strength ratio Kσ(T) is less than or equal to 0.95, the upper limit value is taken; When the high-temperature and normal-temperature yield strength ratio 0.95 < Kσ(T) < 1.05, the middle value is taken; When the high-temperature and normal-temperature yield strength ratio Kσ(T) is greater than or equal to 1.05, the lower limit value is taken.

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