A method and simulation device for measuring the temperature and strain of a cement sheath in an oil and gas well

Abstract

The present invention discloses a method and a simulation device for measuring the temperature and strain of an oil and gas well cement sheath, belonging to the technical field of oil and gas well engineering. The method for measuring the temperature and strain of an oil and gas well cement sheath includes: establishing a simulation device for simulating the working conditions of an oil and gas well, and forming a simulated annulus for injecting cement slurry in the simulation device; selecting measurement points to be measured for temperature and strain in the simulated annulus, and presetting temperature and strain measurement devices capable of measuring temperature and strain at the measurement points to be measured; injecting cement slurry into the simulated annulus, and the cement slurry fills the simulated annulus to form a cement sheath; measuring the temperature and strain of the measurement points to be measured during the solidification process of the cement sheath through the temperature and strain measurement devices, collecting the temperature and strain of the measurement points to be measured during the solidification process of the cement sheath, and obtaining the temperature data and strain data of the measurement points to be measured during the solidification process of the cement sheath. The method for measuring the temperature and strain of an oil and gas well cement sheath of the present invention can measure the temperature and strain of the oil and gas well cement sheath in real time, effectively and comprehensively.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas well engineering, and in particular to a method and a simulation device for measuring the temperature and strain of a cement ring of an oil and gas well. Background Art

[0002] In the field of oil and gas well engineering, during cementing engineering construction, after the oil well cement is injected into the well and displaced to the annular space between the casing and the formation or between the casings, the cement slurry solidifies within the designed time and eventually forms a cement ring with the ability to isolate the annulus, thereby achieving the purpose of isolating fluids from different formations and providing a safe channel for normal production of oil and gas wells.

[0003] However, with the continuous deepening of exploration and development, oil and gas well resources are buried deep, the temperature is high, the formation pressure and geological conditions are complex, and at the same time, large-scale volume fracturing and other processes are widely used, and the temperature, pressure and other working conditions faced by the cement sheath in the well are becoming more and more harsh. If the cement sheath cannot withstand the effects of various temperature and pressure loads, cracks will appear in the cement sheath or micro-annulus will be generated at the interface of cement sheath-casing / cement sheath-formation, thereby forming a channel for formation fluid crossflow. In severe cases, annular pressure will occur, which will bring safety hazards to oil and gas wells, affect the production of single wells, reduce the recovery rate of oil and gas reservoirs, and restrict the safe and efficient development of oil and gas wells.

[0004] At present, in order to simulate and verify whether the cement ring can withstand the downhole temperature and pressure conditions, major oil service companies at home and abroad have designed full-scale or proportional cement ring integrity indoor simulation devices, which test and study the sealing integrity of the cement ring under downhole conditions by applying temperature and pressure loads. However, at present, these simulation devices generally stick strain gauges on the outer wall of the cement ring after the cement ring solidifies to measure the stress and strain of the cement ring. Since the strain gauges are stuck on the outer wall of the cement ring, only the stress and strain state at the cement ring interface can be obtained, and the stress and strain changes of the cement ring during the solidification process cannot be measured.

[0005] Furthermore, the temperature data and stress state data of the cement ring under downhole conditions are important prerequisites for studying the failure mechanism of cement ring sealing, developing targeted high-performance cement slurry systems to ensure sealing, and achieving effective control of cement ring integrity. The effective measurement of temperature data and stress state data under downhole conditions is a key issue that needs to be urgently solved in this field of research; being able to accurately obtain the temperature and stress state of the cement ring under downhole conditions is conducive to the reasonable design of the cement slurry system, so that the cement ring can withstand downhole temperature and pressure conditions, thereby ensuring the sealing integrity of the cement ring under complex temperature and pressure conditions, and can also provide an important basis for the detection and evaluation of cement ring integrity in oil and gas wells. At present, there is no effective method for measuring the temperature and stress state of the cement ring under downhole conditions. Therefore, there is an urgent need for a method that can effectively and comprehensively measure the temperature and strain of cement rings in oil and gas wells. Summary of the Invention

[0006] An object of the present invention is to overcome at least one of the above-mentioned deficiencies of the prior art, and to provide a method capable of effectively and comprehensively measuring the temperature and strain of the cement sheath in an oil and gas well, and also to provide a simulation device capable of effectively and comprehensively measuring the temperature and strain of the cement sheath in an oil and gas well.

[0007] The technical solution for the present invention to solve the above technical problems is as follows: A method for measuring the temperature and strain of the cement sheath in an oil and gas well, comprising:

[0008] Establish a simulation device for simulating the working conditions of an oil and gas well, and a simulated annulus for injecting cement slurry is formed inside the simulation device;

[0009] Select a measurement point where the temperature and strain need to be measured in the simulated annulus, and preset a temperature and strain measurement device capable of measuring the temperature and strain at the measurement point;

[0010] Inject cement slurry into the simulated annulus, and the cement slurry fills the simulated annulus to form a cement sheath;

[0011] Measure the temperature and strain of the measurement point during the solidification process of the cement sheath through the temperature and strain measurement device, collect the temperature and strain of the measurement point during the solidification process of the cement sheath, and obtain the temperature data and strain data of the measurement point during the solidification process of the cement sheath.

[0012] The beneficial effect of the present invention is as follows: In this embodiment, by selecting a measurement point where the temperature and strain need to be measured in the simulated annulus, and presetting a temperature and strain measurement device capable of measuring the temperature and strain at the measurement point, measuring the temperature and strain of the measurement point during the solidification process of the cement sheath through the temperature and strain measurement device, and collecting the temperature and strain of the measurement point during the solidification process of the cement sheath, the temperature data and strain data of the measurement point during the solidification process of the cement sheath can be obtained; further, since the measurement point can be selected at any position in the simulated annulus where the temperature and strain need to be measured, thus, a temperature and strain measurement device can be preset at any position in the simulated annulus where the temperature and strain need to be measured, and by measuring the temperature and strain of the measurement point during the solidification process of the cement sheath through the temperature and strain measurement device, the temperature and strain at any position including the inside, outer wall, and inner wall of the cement sheath can be obtained, so that the temperature and strain during the solidification process of the cement sheath can be effectively measured, and the temperature and strain at any position including the inside, outer wall, and inner wall of the cement sheath can be measured and obtained, which can provide more comprehensive data support for the service of the cement sheath and is beneficial to the reasonable design of the cement slurry system.

[0013] In addition, based on the above technical solutions, the present invention can also be improved as follows and can also have the following additional technical features.

[0014] According to an embodiment of the present invention, the method for measuring the temperature and strain of the cement sheath in an oil and gas well further includes:

[0015] Presetting a curing temperature and a curing pressure, regulating the temperature and pressure of the cement sheath according to the preset curing temperature and curing pressure, and curing the cement sheath until curing is completed under the preset curing temperature and curing pressure;

[0016] Regulating the temperature and pressure of the cured cement sheath, measuring the temperature and strain of the measured point on the cement sheath under the current temperature and pressure conditions through the temperature and strain measuring device, collecting the temperature and strain of the cement sheath under the current temperature and pressure conditions, and obtaining the temperature data and strain data of the measured point on the cement sheath under the current temperature and pressure conditions.

[0017] In this embodiment, the cement sheath is cured until curing is completed under the preset curing temperature and curing pressure. The structure of the cement sheath is affected by the preset curing temperature and curing pressure, reducing or avoiding cracks or micro-annular gaps in the cement sheath; further, regulating the temperature and pressure of the cured cement sheath, and measuring the temperature and strain of the measured point on the cement sheath under the current temperature and pressure conditions through the temperature and strain measuring device, the temperature and strain of the measured point on the cured cement sheath under different temperature and pressure conditions can be measured, and the temperature data and strain data of the measured point on the cement sheath under different temperature and pressure conditions can be obtained, which is beneficial to understanding the situation of the cement sheath under downhole temperature and pressure conditions, beneficial to reasonably designing the cement slurry system, and providing data support for the research on the sealing integrity of the cement sheath.

[0018] According to an embodiment of the present invention, during the curing process of the cement sheath under the preset curing temperature and curing pressure, the temperature and strain of the measured point during the curing process of the cement sheath are measured through the temperature and strain measuring device, the temperature and strain of the measured point during the curing process of the cement sheath are collected, and the temperature data and strain data of the measured point during the curing process of the cement sheath are obtained. In this embodiment, the temperature and strain of the measured point during the curing process of the cement sheath are measured through the temperature and strain measuring device, and the temperature data and strain data of the measured point during the curing process of the cement sheath are obtained, so as to further understand the temperature and strain conditions of the measured point during the curing process of the cement sheath.

[0019] According to an embodiment of the present invention, the regulation of the temperature and pressure of the cement sheath after curing is specifically as follows: according to the temperature and pressure conditions during the well completion process that the actual cement sheath experiences after curing in the oil and gas well, the temperature and pressure of the cement sheath after curing are regulated. In this embodiment, by regulating the temperature and pressure of the cement sheath after curing according to the temperature and pressure conditions during the well completion process that the actual cement sheath experiences after curing in the oil and gas well, the temperature and strain of the measurement point can be measured targeted under the temperature and pressure conditions of the oil and gas well, and the temperature data and strain data of the measurement point of the cement sheath after curing under the temperature and pressure conditions of the oil and gas well can be obtained, which is convenient for designing a cement slurry system that can withstand the temperature and pressure conditions of the oil and gas well, and can also test whether the cement sheath after curing can withstand the temperature and pressure received under the current oil and gas well, providing data support for the research on the sealing integrity of the cement sheath.

[0020] According to an embodiment of the present invention, the number of pressure application cycles is preset according to the cyclic pressure condition during the well completion process that the actual cement sheath experiences after curing in the oil and gas well. During the process of regulating the pressure of the cement sheath after curing, the cement sheath is cyclically pressurized according to the preset number of pressure application cycles until the number of cycles is completed. In this embodiment, by presetting the number of pressure application cycles according to the cyclic pressure condition during the well completion process that the actual cement sheath experiences after curing in the oil and gas well, the temperature data and strain data of the measurement point of the cement sheath under the cyclic pressure condition during the well completion process in the oil and gas well can be measured by the temperature and strain measurement device, which is convenient for testing whether the cement sheath can withstand the cyclic pressure condition during the well completion process in the oil and gas well.

[0021] According to an embodiment of the present invention, the method for measuring the temperature and strain of the cement sheath in the oil and gas well further includes:

[0022] According to the temperature and pressure conditions of the production process in the oil and gas well after the actual cement sheath completion, the temperature and pressure of the cement sheath after completion are regulated. And according to the cyclic pressure condition of the production process in the oil and gas well after the actual cement sheath completion, the number of pressure application cycles is preset. During the process of regulating the pressure of the cement sheath after completion, the cement sheath is cyclically pressurized according to the preset number of pressure application cycles until the number of cycles is completed. In this embodiment, according to the temperature and pressure conditions of the production process in the oil and gas well after the actual cement sheath completion, the temperature and pressure of the cement sheath after completion are regulated, so that the temperature and strain of the measurement point can be measured targeted under the temperature and pressure conditions of the cement sheath in the oil and gas well, and the temperature data and strain data of the measurement point under the temperature and pressure conditions of the cement sheath in the oil and gas well after completion can be obtained; in addition, in this embodiment, according to the cyclic pressure condition of the production process in the oil and gas well after the actual cement sheath curing is completed, the number of pressure application cycles is preset, and the temperature data and strain data of the measurement point under the cyclic pressure condition of the production process in the oil and gas well can be measured by the temperature strain measurement device, which is convenient to check whether the cement sheath can withstand the cyclic pressure condition of the production process in the oil and gas well.

[0023] According to an embodiment of the present invention, a plurality of the measurement points are selected in the vertical direction, the plurality of measurement points are spaced apart in the vertical direction, and the temperature strain measurement devices are respectively preset at the selected plurality of measurement points. In this embodiment, by selecting a plurality of the measurement points in the vertical direction and respectively presetting the temperature strain measurement devices at the selected plurality of measurement points, the temperature and strain of the measurement points at different height positions of the cement sheath under various conditions can be measured by the temperature strain measurement device, so as to obtain the temperature data and strain data of the measurement points at different height positions of the cement sheath.

[0024] According to an embodiment of the present invention, a plurality of points to be measured are selected in the circumferential direction, and a plurality of the points to be measured are respectively selected on different height planes of the simulated annulus. The plurality of points to be measured located on the same height plane are circumferentially spaced apart, and the radial distances from the plurality of points to be measured located on the same height plane to the vertical center of the simulated annulus are not equal. The temperature and strain measurement devices are respectively preset at the plurality of points to be measured, and the distances from the plurality of temperature and strain measurement devices located on the same height plane to the vertical center of the simulated annulus in the circumferential direction are not equal. In this embodiment, by selecting a plurality of the points to be measured in the circumferential direction, the plurality of points to be measured located on the same height plane are circumferentially spaced apart, and the radial distances from the plurality of points to be measured located on the same height plane to the vertical center of the simulated annulus are not equal, and the temperature and strain measurement devices are respectively preset at the selected plurality of points to be measured, so that the temperature and strain at different thickness positions on the same height plane of the cement sheath under various working conditions can be measured by the temperature and strain measurement devices, thereby obtaining the temperature data and strain data at different thickness positions on the same height plane of the cement sheath.

[0025] According to an embodiment of the present invention, the simulation device includes a simulated formation and a simulated casing. A columnar hollow cavity is provided in the simulated formation, and the simulated casing is vertically inserted into the columnar hollow cavity. The simulated casing is coaxial with the simulated formation, and the simulated annulus is defined between the simulated formation and the simulated casing;

[0026] The method for measuring the temperature and strain of the oil and gas well cement sheath further includes:

[0027] An installation hole is provided on the simulated formation near the point to be measured along the thickness direction of the simulated formation. The installation hole penetrates through the simulated formation and communicates with the simulated annulus, and the temperature and strain measurement device is installed in the installation hole and extends into the simulated annulus.

[0028] In this embodiment, by providing the installation hole on the simulated formation, it is convenient to reliably install the temperature and strain measurement device through the installation hole, and it is beneficial to adjust the position of the temperature and strain measurement device extending into the simulated annulus, facilitating the rapid installation of the temperature and strain measurement device.

[0029] According to an embodiment of the present invention, an optical fiber temperature and strain sensor is used as the temperature and strain measuring device, and the optical fiber temperature and strain sensor is electrically connected to the signal processing system through an optical fiber line, or the optical fiber temperature and strain sensor is wirelessly communicatively connected to the signal processing system. In this embodiment, an optical fiber temperature and strain sensor is used as the temperature and strain measuring device. The optical fiber temperature and strain sensor measures the Bragg wavelength spectrum of the internal transmission grating to realize the measurement of the temperature and strain parameters of the cement sheath. Moreover, the optical fiber temperature and strain sensor has the characteristics of real-time and non-destructive measurement. At the same time, the optical fiber temperature and strain sensor can be designed into any shape. Therefore, the shape of the optical fiber temperature and strain sensor can be changed according to the measurement position requirements, which is convenient for the optical fiber temperature and strain sensor to accurately measure the cement sheath. Further, the optical fiber temperature and strain sensor has the ability to resist harsh environments including high temperatures and chemical erosion, can be measured in a variety of harsh environments, and is beneficial to ensuring the reliability of the measurement. Further, by electrically connecting the optical fiber temperature and strain sensor to the signal processing system through an optical fiber line, or wirelessly communicatively connecting the optical fiber temperature and strain sensor to the signal processing system, it is convenient to measure the temperature and strain states of the cement sheath in real time and continuously during the solidification process and subsequent drilling, completion and production processes.

[0030] According to an embodiment of the present invention, the method for measuring the temperature and strain of the cement sheath in an oil and gas well further includes:

[0031] Combined with the elastic modulus of the cement slurry injected into the simulated annulus, the obtained strain data of the point to be measured is brought into the calculation formula:

[0032] Stress = Strain × Elastic modulus,

[0033] Perform calculations to obtain the stress data of the point to be measured.

[0034] In this embodiment, combined with the elastic modulus of the cement slurry injected into the simulated annulus, the strain data of the point to be measured is converted into stress data, which is convenient for judging the change of stress data under various pressure conditions.

[0035] In addition, a simulation device for measuring the temperature and strain of the cement sheath in an oil and gas well provided in this embodiment includes:

[0036] A simulated formation, in which a columnar hollow cavity is provided;

[0037] A simulated casing, vertically inserted into the columnar hollow cavity. The simulated formation is coaxial with the simulation device, and a simulated annulus for injecting cement slurry is defined between the simulated formation and the simulated casing;

[0038] A temperature and strain measurement device is arranged in the simulated annulus. When cement slurry is injected into the simulated annulus, the cement slurry fills the simulated annulus to form a cement sheath, and the temperature and strain measurement device is in contact with the cement sheath and can measure the temperature and strain of the cement sheath.

[0039] In the simulation device for measuring the temperature and strain of the cement sheath in an oil and gas well in this embodiment, a simulated annulus for injecting cement slurry is defined between the simulated formation and the simulated casing, and a temperature and strain measurement device is arranged in the simulated annulus. The cement slurry fills the simulated annulus to form a cement sheath, and the temperature and strain measurement device is in contact with the cement sheath and can measure the temperature and strain of the cement sheath; further, the position where the simulation device is simulated can be any position in the simulated annulus where the temperature and strain need to be measured. Thus, the temperature and strain at any position in the simulated annulus where the temperature and strain need to be measured can be used to obtain the temperature and strain at any position of the cement sheath, including the inside, outer wall, and inner wall of the cement sheath. Therefore, the temperature and strain of the cement sheath under different working conditions can be effectively measured, and the temperature and strain at any position, including the inside, outer wall, and inner wall of the cement sheath, can be measured and obtained, which can provide more comprehensive data support for the service of the cement sheath and is beneficial to the reasonable design of the cement slurry system.

[0040] According to an embodiment of the present invention, a plurality of the temperature and strain measurement devices are provided, and the plurality of temperature and strain measurement devices are arranged at intervals in the vertical direction. In this embodiment, by arranging a plurality of the temperature and strain measurement devices at intervals in the vertical direction, the temperature and strain of the measurement points at different height positions of the cement sheath under various working conditions can be measured by the temperature and strain measurement devices, so as to obtain the temperature data and strain data at different height positions of the cement sheath.

[0041] According to an embodiment of the present invention, a plurality of the temperature and strain measurement devices are respectively arranged at circumferential intervals on different height planes of the simulated annulus. The plurality of measurement points located on the same height plane are arranged at circumferential intervals, and the distances from the plurality of temperature and strain measurement devices located on the same height plane to the vertical center of the simulated annulus are not equal. In this embodiment, by respectively arranging a plurality of the temperature and strain measurement devices at circumferential intervals on different height planes of the simulated annulus, the plurality of measurement points located on the same height plane are arranged at circumferential intervals, and the distances from the plurality of temperature and strain measurement devices located on the same height plane to the vertical center of the simulated annulus are not equal, so that the temperature and strain at different thickness positions of the same height plane of the cement sheath under various working conditions can be measured by the temperature and strain measurement devices, and the temperature data and strain data at different thickness positions of the same height plane of the cement sheath can be obtained.

[0042] According to an embodiment of the present invention, mounting holes are provided along the thickness direction of the simulated formation. The mounting holes penetrate through the simulated formation and communicate with the simulated annulus. The temperature and strain measuring device is installed in the mounting holes and extends into the simulated annulus. In this embodiment, by providing mounting holes in the simulated formation, it is convenient to reliably install the temperature and strain measuring device through the mounting holes, and it is beneficial to adjust the position of the temperature and strain measuring device extending into the simulated annulus, facilitating the rapid installation of the temperature and strain measuring device.

[0043] According to an embodiment of the present invention, the temperature and strain measuring device includes an optical fiber temperature and strain sensor;

[0044] The simulation device for measuring the temperature and strain of the cement sheath of an oil and gas well further includes:

[0045] A signal processing system, the optical fiber temperature and strain sensor is electrically connected to the signal processing system through an optical fiber line, or the optical fiber temperature and strain sensor is wirelessly communicatively connected to the signal processing system.

[0046] The temperature and strain measuring device in this embodiment includes an optical fiber temperature and strain sensor. The optical fiber temperature and strain sensor measures the Bragg wavelength spectrum of the internal transmission grating to achieve the measurement of the temperature and strain parameters of the cement sheath. Moreover, the optical fiber temperature and strain sensor has the characteristics of real-time and non-destructive measurement. At the same time, the optical fiber temperature and strain sensor can also be designed into any shape. Therefore, the shape of the optical fiber temperature and strain sensor can be changed according to the measurement position requirements, facilitating the accurate measurement of the cement sheath by the optical fiber temperature and strain sensor; further, the optical fiber temperature and strain sensor has the ability to resist harsh environments including high temperatures and chemical erosion, can be measured in a variety of harsh environments, and is beneficial to ensuring the reliability of the measurement. Further, by electrically connecting the optical fiber temperature and strain sensor to the signal processing system through an optical fiber line, or wirelessly communicatively connecting the optical fiber temperature and strain sensor to the signal processing system, it is convenient to measure the temperature and strain states of the cement sheath in real time and continuously during the solidification process and subsequent well drilling and production processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0048] Figure 1 Schematic diagram of the installation of the optical fiber temperature and strain sensor according to the embodiment of the present invention in the simulated annulus;

[0049] Figure 2 ForFigure 1 Schematic diagram of the fiber optic temperature and strain sensor buried in the cement sheath;

[0050] Figure 3 Schematic diagram of multiple fiber optic temperature and strain sensors buried in the cement sheath in both the vertical and horizontal directions in the embodiment of the present invention;

[0051] Figure 4 is Figure 1 Top view after cutting upward along the middle of the sealing plug in the vertical direction;

[0052] Figure 5 is Figure 2 Top view after cutting upward along the middle of the sealing plug in the vertical direction;

[0053] Figure 6 is Figure 3 Top view after cutting upward along the middle of the sealing plug at the middle position in the vertical direction;

[0054] Figure 7 Top view of the sealing plug in the embodiment of the present invention after cutting upward along its middle in the vertical direction.

[0055] In the drawings, the list of components represented by each reference numeral is as follows:

[0056] 1. Simulated formation, 2. Simulated casing, 3. Simulated annulus, 4. Sealing plug, 5. Fiber optic temperature and strain sensor, 6. Signal processing system, 7. Cement sheath, 40. Through hole, 41. Arc avoidance groove, 42. Arc depression groove, 50. Fiber optic cable. Detailed implementation manners

[0057] To make the objectives, technical solutions and advantages of the present application clearer, the following will further describe in detail the implementation manners of the present application with reference to the drawings.

[0058] To be able to more clearly understand the above objectives, features and advantages of the present invention, the following will further describe the present invention in detail with reference to the drawings and specific implementation manners. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0059] Many specific details are set forth in the following description to facilitate a thorough understanding of the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0060] This embodiment provides a method for measuring the temperature and strain of the cement sheath of an oil and gas well, and a simulation device for measuring the temperature and strain of the cement sheath of an oil and gas well that can implement the method for measuring the temperature and strain of the cement sheath of an oil and gas well in this embodiment, asFigures 1 to 6 As shown, in this embodiment, the method for measuring the temperature and strain of the cement sheath in an oil and gas well is described in combination with this simulation device. The method for measuring the temperature and strain of the cement sheath in an oil and gas well includes:

[0061] Establish a simulation device for simulating the working conditions of an oil and gas well, and a simulated annulus 3 for injecting cement slurry is formed inside the simulation device;

[0062] Select measurement points in the simulated annulus 3 where the temperature and strain need to be measured, and preset temperature and strain measurement devices capable of measuring temperature and strain at the measurement points;

[0063] Inject cement slurry into the simulated annulus 3, and the cement slurry fills the simulated annulus 3 to form a cement sheath 7;

[0064] Measure the temperature and strain of the measurement points during the solidification process of the cement sheath 7 through the temperature and strain measurement devices, collect the temperature and strain of the measurement points during the solidification process of the cement sheath 7, and obtain the temperature data and strain data of the measurement points during the solidification process of the cement sheath 7.

[0065] In this embodiment, as Figures 1 to 6 shown, by selecting measurement points in the simulated annulus 3 where the temperature and strain need to be measured, and presetting temperature and strain measurement devices capable of measuring temperature and strain at the measurement points, measuring the temperature and strain of the measurement points during the solidification process of the cement sheath 7 through the temperature and strain measurement devices, and collecting the temperature and strain of the measurement points during the solidification process of the cement sheath 7, the temperature data and strain data of the measurement points during the solidification process of the cement sheath 7 can be obtained; further, since the measurement points can be selected at any position in the simulated annulus 3 where the temperature and strain need to be measured, thus, by presetting temperature and strain measurement devices at any position in the simulated annulus 3 where the temperature and strain need to be measured, and measuring the temperature and strain of the measurement points during the solidification process of the cement sheath 7 through the temperature and strain measurement devices, the temperature and strain at any position including the inside, outer wall, and inner wall of the cement sheath 7 can be obtained, so that the temperature and strain during the solidification process of the cement sheath 7 can be effectively measured, and the temperature and strain at any position including the inside, outer wall, and inner wall of the cement sheath 7 can be measured and obtained, which can provide more comprehensive data support for the service of the cement sheath 7 and is beneficial to the reasonable design of the cement slurry system.

[0066] In this embodiment, the "measurement points" in this embodiment refer to the measurement points or positions where the temperature and pressure need to be measured. After injecting cement slurry into the simulated annulus 3 to form a cement sheath 7, the measurement points correspond to the positions where the temperature and strain measurement devices measure the cement sheath 7; the selection of the measurement points also corresponds to the positions of the cement sheath 7 that need to be measured.

[0067] It should be noted that the specific structure of the simulation device formed by the above-mentioned "establishing a simulation device for simulating the working conditions of oil and gas wells" can be various, and the simulation device can also be formed by improving the simulation device for simulating the working conditions of oil and gas wells in the prior art. In addition, the "cement ring 7" formed by filling the cement slurry in the simulation annulus 3 in this embodiment is a ring-shaped cement structure for simulating the actual cement ring, that is, a simulated cement ring. The "actual cement ring" in this embodiment refers to the ring-shaped cement structure formed during the actual construction of the oil and gas well.

[0068] In one embodiment of the present invention, the method for measuring the temperature and strain of the cement ring of an oil and gas well further includes:

[0069] Preset the curing temperature and curing pressure, regulate the temperature and pressure of the cement ring 7 according to the preset curing temperature and curing pressure, and cure the cement ring 7 at the preset curing temperature and curing pressure until the curing is completed;

[0070] Regulate the temperature and pressure of the cured cement ring 7, measure the temperature and strain of the measurement point of the cement ring 7 under the current temperature and pressure conditions through the temperature and strain measurement device, collect the temperature and strain of the cement ring 7 under the current temperature and pressure conditions, and obtain the temperature data and strain data of the measurement point of the cement ring 7 under the current temperature and pressure conditions.

[0071] In this embodiment, the cement ring 7 is cured at the preset curing temperature and curing pressure until the curing is completed. The structure of the cement ring 7 is affected by the preset curing temperature and curing pressure, reducing or avoiding cracks or micro-annular gaps in the cement ring 7. Further, the temperature and pressure of the cured cement ring 7 are regulated, and the temperature and strain of the measurement point of the cement ring 7 under the current temperature and pressure conditions are measured through the temperature and strain measurement device, so that the temperature and strain of the measurement point of the cured cement ring 7 under different temperature and pressure conditions can be measured, and the temperature data and strain data of the measurement point of the cement ring 7 under different temperature and pressure conditions can be obtained, which is beneficial to understanding the situation of the cement ring bearing downhole temperature and pressure conditions, beneficial to the reasonable design of the cement slurry system, and provides data support for the research on the sealing integrity of the cement ring. Further, the specific values of the preset curing temperature and curing pressure can be set according to the relevant experience of some actual oil and gas wells. There are various specific values of the curing temperature and curing pressure, and they are used to simulate different oil and gas well conditions, and the curing temperature and curing pressure are also different. Further, the preset curing temperature and curing pressure can be preset while establishing the simulation device, or can be preset before curing the cement ring 7, and the specific values of the curing temperature and curing pressure are obtained by measurement in actual oil and gas wells.

[0072] In an embodiment of the present invention, during the curing of the cement sheath 7 under a preset curing temperature and curing pressure, the temperature and strain of the measurement points to be measured during the curing process of the cement sheath 7 are measured by a temperature and strain measurement device, the temperature and strain of the measurement points to be measured during the curing process of the cement sheath 7 are collected, and the temperature data and strain data of the measurement points to be measured during the curing process of the cement sheath 7 are obtained. In this embodiment, by measuring the temperature and strain of the measurement points to be measured during the curing process of the cement sheath 7 by a temperature and strain measurement device, the temperature data and strain data of the measurement points to be measured during the curing process of the cement sheath 7 are obtained, so as to understand the temperature and strain conditions of the measurement points to be measured during the curing process of the cement sheath 7.

[0073] In an embodiment of the present invention, the regulation and control of the temperature and pressure of the cured cement sheath 7 are specifically as follows: The temperature and pressure of the cured cement sheath 7 are regulated and controlled according to the temperature and pressure conditions during the well completion process that the actual cement sheath is subjected to in the oil and gas well after curing. In this embodiment, the temperature and pressure of the cured cement sheath 7 are regulated and controlled according to the temperature and pressure conditions during the well completion process that the actual cement sheath is subjected to in the oil and gas well after curing. Furthermore, the temperature and strain of the measurement points to be measured under the temperature and pressure conditions of the oil and gas well of the cement sheath 7 can be measured targeted, the temperature data and strain data of the measurement points to be measured under the temperature and pressure conditions of the oil and gas well of the cement sheath 7 can be obtained, which is convenient for designing a cement slurry system that can withstand the temperature and pressure conditions of the oil and gas well, and can also test whether the cement sheath 7 can withstand the temperature and pressure received under the current oil and gas well, providing data support for the research on the sealing integrity of the cement sheath. It should be noted that the "well completion process" in this embodiment refers to the construction process from after the curing of the oil and gas well to before the production operation. The specific values of the temperature and pressure during the well completion process can be measured in the actual oil and gas well. The "temperature and pressure conditions during the well completion process that the actual cement sheath is subjected to in the oil and gas well after curing" refers to the temperature and pressure conditions that the actual cement sheath in the oil and gas well is subjected to during the well completion construction process. In addition, the regulation and control of the temperature and pressure are to make the cement sheath 7 simulate the temperature and pressure environment of the actual cement sheath and simulate it respectively at different construction stages.

[0074] In an embodiment of the present invention, according to the cyclic pressure condition during the well completion process that the actual cement sheath will be subjected to after curing in the oil and gas well, a preset number of pressurization cycles is set. During the process of regulating the pressure of the cured cement sheath 7, the cement sheath 7 is cyclically pressurized according to the preset number of pressurization cycles until the number of cycles is completed. In this embodiment, by setting the preset number of pressurization cycles according to the cyclic pressure condition during the well completion process that the actual cement sheath will be subjected to after curing in the oil and gas well, the temperature data and strain data of the measurement points of the cement sheath 7 under the cyclic pressure condition during the well completion process in the oil and gas well can be measured by a temperature and strain measurement device, which is convenient for testing whether the cement sheath 7 can withstand the cyclic pressure condition during the well completion process in the oil and gas well. In addition, the "cyclic pressure condition during the well completion process that the actual cement sheath will be subjected to after curing in the oil and gas well" refers to the temperature and pressure conditions that the actual cement sheath in the oil and gas well is subjected to during the well completion construction process.

[0075] An embodiment of the present invention, the method for measuring the temperature and strain of the cement sheath in the oil and gas well further includes:

[0076] According to the temperature and pressure conditions during the production process that the actual cement sheath will be subjected to after well completion in the oil and gas well, the temperature and pressure of the cement sheath 7 after well completion are regulated. And according to the cyclic pressure condition during the production process that the actual cement sheath will be subjected to after well completion in the oil and gas well, a preset number of pressurization cycles is set. During the process of regulating the pressure of the cement sheath 7 after well completion, the cement sheath 7 is cyclically pressurized according to the preset number of pressurization cycles until the number of cycles is completed. In this embodiment, by regulating the temperature and pressure of the cement sheath 7 after well completion according to the temperature and pressure conditions during the production process that the actual cement sheath will be subjected to after well completion in the oil and gas well, the temperature and strain of the measurement points of the cement sheath 7 under the temperature and pressure conditions in the oil and gas well can be measured in a targeted manner, and the temperature data and strain data of the measurement points of the cement sheath 7 under the temperature and pressure conditions in the oil and gas well after well completion can be obtained. In addition, in this embodiment, by setting the preset number of pressurization cycles according to the cyclic pressure condition during the production process that the actual cement sheath will be subjected to after curing in the oil and gas well, the temperature data and strain data of the measurement points of the cement sheath 7 under the cyclic pressure condition during the production process in the oil and gas well can be measured by a temperature and strain measurement device, which is convenient for testing whether the cement sheath 7 can withstand the cyclic pressure condition during the production process in the oil and gas well. It should be noted that the "production process" in this embodiment refers to the exploitation operation process after the drilling and well completion of the oil and gas well, and the specific values of the temperature and pressure during the production process can be measured in the actual oil and gas well. In addition, the "temperature and pressure conditions during the production process that the actual cement sheath will be subjected to after well completion in the oil and gas well" refers to the temperature and pressure conditions that the actual cement sheath in the oil and gas well is subjected to during the production process, and the well completion process of the cement sheath 7 simulates the actual well completion process of the oil and gas well.

[0077] An embodiment of the present invention, such as Figure 3As shown in the figure, multiple measurement points to be measured are selected in the vertical direction. The multiple measurement points to be measured are spaced apart in the vertical direction, and temperature and strain measurement devices are preset at the selected multiple measurement points respectively. In this embodiment, by selecting multiple measurement points to be measured in the vertical direction and presetting temperature and strain measurement devices at the selected multiple measurement points respectively, the temperature and strain of the measurement points at different height positions of the cement sheath 7 under various working conditions can be measured by the temperature and strain measurement devices, so as to obtain the temperature data and strain data of the measurement points at different height positions of the cement sheath 7.

[0078] An embodiment of the present invention, as Figure 3 、 Figure 6 As shown in the figure, multiple measurement points to be measured are selected in the circumferential direction. Multiple measurement points are respectively selected on different height planes of the simulated annulus 3. The multiple measurement points located on the same height plane are circumferentially spaced apart, and the radial distances from the multiple measurement points located on the same height plane to the vertical center of the simulated annulus 3 are not equal. Temperature and strain measurement devices are preset at the multiple measurement points respectively, and the distances from the multiple temperature and strain measurement devices located on the same height plane to the vertical center of the simulated annulus 3 in the circumferential direction are not equal. In this embodiment, by selecting multiple measurement points to be measured in the circumferential direction, the multiple measurement points located on the same height plane are circumferentially spaced apart, and the radial distances from the multiple measurement points located on the same height plane to the vertical center of the simulated annulus 3 are not equal, and temperature and strain measurement devices are preset at the selected multiple measurement points respectively, the temperature and strain of the cement sheath 7 at different thickness positions on the same height plane under various working conditions can be measured by the temperature and strain measurement devices, so as to obtain the temperature data and strain data of the cement sheath 7 at different thickness positions on the same height plane. It should be noted that the temperature and strain measurement devices in this embodiment are set before injecting cement slurry into the simulated annulus 3.

[0079] An embodiment of the present invention, as Figures 1 to 6 As shown in the figure, the simulation device includes a simulated formation 1 and a simulated casing 2. A columnar hollow cavity is provided in the simulated formation 1. The simulated casing 2 is vertically inserted into the columnar hollow cavity. The simulated casing 2 is coaxial with the simulated formation 1, and a simulated annulus 3 is defined between the simulated formation 1 and the simulated casing 2;

[0080] The method for measuring the temperature and strain of the oil and gas well cement sheath further includes:

[0081] An installation hole is provided in the simulated formation 1 near the measurement point to be measured along the thickness direction of the simulated formation 1. The installation hole penetrates through the simulated formation 1 and communicates with the simulated annulus 3. The temperature and strain measurement device is installed in the installation hole and the temperature and strain measurement device extends into the simulated annulus 3.

[0082] In this embodiment, by providing mounting holes on the simulated formation 1, it is convenient to reliably mount the temperature and strain measurement device through the mounting holes, and it is beneficial to adjust the position of the temperature and strain measurement device extending into the simulated annulus 3, facilitating the rapid installation of the temperature and strain measurement device. It should be noted that the mounting holes provided on the simulated formation 1 in this embodiment are opened before injecting cement slurry into the simulated annulus 3, and the temperature and strain measurement device is also mounted in the mounting holes before injecting cement slurry into the simulated annulus 3.

[0083] An embodiment of the present invention, as Figures 1 to 6 shown, uses an optical fiber temperature and strain sensor 5 as the temperature and strain measurement device, and electrically connects the optical fiber temperature and strain sensor 5 to the signal processing system 6 through an optical fiber line 50, or wirelessly communicates the optical fiber temperature and strain sensor 5 with the signal processing system 6. In this embodiment, an optical fiber temperature and strain sensor 5 is used as the temperature and strain measurement device. The optical fiber temperature and strain sensor 5 measures the Bragg wavelength spectrum of the internal transmission grating to realize the measurement of temperature and strain parameters of the cement sheath 7. Moreover, the optical fiber temperature and strain sensor 5 has the characteristics of real-time and non-destructive measurement. At the same time, the optical fiber temperature and strain sensor 5 can also be designed into any shape. Therefore, the shape of the optical fiber temperature and strain sensor 5 can be changed according to the measurement position requirements, facilitating the accurate measurement of the cement sheath 7 by the optical fiber temperature and strain sensor 5; further, the optical fiber temperature and strain sensor 5 has the ability to resist harsh environments including high temperatures and chemical erosion, can be measured in a variety of harsh environments, and is beneficial to ensuring the reliability of the measurement. Further, by electrically connecting the optical fiber temperature and strain sensor 5 to the signal processing system 6 through the optical fiber line 50, or wirelessly communicating the optical fiber temperature and strain sensor 5 with the signal processing system 6, it is convenient to measure the temperature and strain states of the cement sheath 7 in real time and continuously during the solidification process and subsequent drilling, completion, and production processes, providing data support for studying the sealing failure mechanism of the cement sheath 7, specifically developing a high-performance cement slurry system to ensure sealing, and effectively controlling the integrity of the cement sheath 7. It should be noted that "drilling and completion" in this embodiment includes the drilling construction and completion construction carried out after the cement slurry has solidified.

[0084] An embodiment of the present invention, the method for measuring the temperature and strain of the oil and gas well cement sheath further includes:

[0085] Combined with the elastic modulus of the cement slurry injected into the simulated annulus 3, substitute the obtained strain data of the point to be measured into the calculation formula:

[0086] Stress = Strain × Elastic Modulus,

[0087] Perform the calculation to obtain the stress data of the point to be measured.

[0088] In this embodiment, in combination with the elastic modulus of the cement slurry injected into the simulated annulus 3, the strain data of the point to be measured is converted into stress data, which is convenient for judging the change of stress data under various pressure conditions. Further, the numerical value of the elastic modulus of the cement slurry in this embodiment can be obtained according to the cement slurry used. For cement slurries with different formulations, the elastic modulus is also different. It should be noted that the "cement slurry in the simulated annulus 3" in combination with the elastic modulus of the cement slurry injected into the simulated annulus 3 is actually the cement sheath 7 formed in the simulated annulus 3, and the elastic modulus of the cement slurry injected into the simulated annulus 3 is also the elastic modulus of the cement sheath 7 formed in the simulated annulus 3.

[0089] In addition, a simulation device for measuring the temperature and strain of an oil and gas well cement sheath provided in this embodiment, as Figures 1 to 6 shown, includes:

[0090] A simulated formation 1, in which a columnar hollow cavity is provided;

[0091] A simulated casing 2, vertically inserted into the columnar hollow cavity. The simulated formation 1 is coaxial with the simulation device, and a simulated annulus 3 for injecting cement slurry is defined between the simulated formation 1 and the simulated casing 2;

[0092] A temperature and strain measurement device, arranged in the simulated annulus 3. When cement slurry is injected into the simulated annulus 3, the cement slurry fills the simulated annulus 3 to form a cement sheath 7, and the temperature and strain measurement device is in contact with the cement sheath 7 and can measure the temperature and strain of the cement sheath 7.

[0093] In this embodiment, as Figures 1 to 6 shown, a simulated annulus 3 for injecting cement slurry is defined between the simulated formation 1 and the simulated casing 2 in the simulation device for measuring the temperature and strain of an oil and gas well cement sheath, and a temperature and strain measurement device is arranged in the simulated annulus 3. The cement slurry fills the simulated annulus 3 to form a cement sheath 7, and the temperature and strain measurement device is in contact with the cement sheath 7 and can measure the temperature and strain of the cement sheath 7; further, the position where the simulation device is simulated can be any position in the simulated annulus 3 where the temperature and strain need to be measured. Thus, through the temperature and strain at any position in the simulated annulus 3 where the temperature and strain need to be measured, the temperature and strain at any position including the inside, outer wall, and inner wall of the cement sheath 7 can be obtained, so that the temperature and strain of the cement sheath 7 under different working conditions can be effectively measured, and the temperature and strain at any position including the inside, outer wall, and inner wall of the cement sheath 7 can be measured and obtained, which can provide more comprehensive data support for the service of the cement sheath 7 and is beneficial to the reasonable design of the cement slurry system. It should be noted that after injecting cement slurry into the simulated annulus 3, the temperature and strain measurement device is finally solidified in the cement sheath 7.

[0094] In this embodiment, as Figures 1 to 6 shown, the simulated formation 1 has a hollow cylindrical structure, the simulated casing 2 has a hollow cylindrical structure, the simulated annulus 3 formed between the simulated formation 1 and the simulated casing 2 is circular, and the cement sheath 7 formed by injecting cement slurry into the simulated annulus 3 has a circular structure. In addition, the simulated formation 1 and the simulated casing 2 in this embodiment can also be set to other structures.

[0095] It should be noted that the simulation device shown as Figures 1 to 6 in this embodiment is only one of the devices for implementing the method for measuring the temperature and strain of the cement sheath in an oil and gas well. The simulation device for implementing the method for measuring the temperature and strain of the cement sheath in an oil and gas well is not limited to the above simulation device. Moreover, the temperature control device and the pressure application device in the simulation device are not shown in the simulation device shown in this embodiment. As Figures 1 to 6 shown in this embodiment, only a part of the simulated formation 1 and the simulated casing 2 in the simulation device are shown respectively. The specific complete structures of the simulated formation 1 and the simulated casing 2 can also refer to existing simulation devices. In addition, the unshown temperature control device, pressure application device and other structures can refer to the simulation devices for simulating the working conditions of oil and gas wells in the prior art. Further, the specific operations for simulating the working conditions of an oil and gas well by the simulation device shown as Figures 1 to 6 in this embodiment can refer to the simulation devices for simulating the working conditions of oil and gas wells in the art. Moreover, the temperature, pressure and pressurization duration of each working condition during the process of simulating the working conditions of an oil and gas well can be set according to the working conditions of the oil and gas well to be simulated. The specific simulation of each working condition can also refer to the existing simulation devices for simulating the working conditions of oil and gas wells in the art, and will not be elaborated here.

[0096] In one embodiment of the present invention, as Figure 3 shown, there are multiple temperature and strain measurement devices, and the multiple temperature and strain measurement devices are arranged at intervals in the vertical direction. In this embodiment, by arranging multiple temperature and strain measurement devices at intervals in the vertical direction, the temperature and strain of the measurement points at different height positions of the cement sheath 7 under various working conditions can be measured by the temperature and strain measurement devices, so as to obtain the temperature data and strain data at different height positions of the cement sheath 7, and a more comprehensive understanding of the temperature and strain conditions of the cement sheath 7 can be achieved.

[0097] In one embodiment of the present invention, as Figure 3 、 Figure 6As shown, a plurality of temperature and strain measurement devices are circumferentially spaced on different height planes of the simulated annulus 3. A plurality of measurement points to be measured on the same height plane are circumferentially spaced, and the distances from the plurality of temperature and strain measurement devices on the same height plane to the vertical center of the simulated annulus 3 are not equal. In this embodiment, by providing a plurality of temperature and strain measurement devices circumferentially spaced on different height planes of the simulated annulus 3, a plurality of measurement points to be measured on the same height plane are circumferentially spaced, and the distances from the plurality of temperature and strain measurement devices on the same height plane to the vertical center of the simulated annulus 3 are not equal, the temperature and strain at different thickness positions on the same height plane of the cement sheath 7 under various working conditions can be measured by the temperature and strain measurement devices, so that the temperature data and strain data at different thickness positions on the same height plane of the cement sheath 7 can be obtained, and a more comprehensive understanding of the temperature and strain conditions of the cement sheath 7 can be achieved.

[0098] An embodiment of the present invention is as Figures 1 to 6 As shown, an installation hole is provided along the thickness direction of the simulated formation 1 on the simulated formation 1. The installation hole penetrates through the simulated formation 1 and communicates with the simulated annulus 3. The temperature and strain measurement device is installed in the installation hole and extends into the simulated annulus 3. In this embodiment, by providing an installation hole on the simulated formation 1, it is convenient to reliably install the temperature and strain measurement device through the installation hole, and it is beneficial to adjust the position of the temperature and strain measurement device extending into the simulated annulus 3, facilitating the rapid installation of the temperature and strain measurement device. In addition, two or more temperature and strain measurement devices can also be installed in the installation hole.

[0099] In this embodiment, as Figures 1 to 6As shown, the temperature and strain measurement device in this embodiment is an optical fiber temperature and strain sensor 5. The installation hole has a circular through-hole structure. Further, in this embodiment, to facilitate the sealing of the installation hole, a sealing plug 4 is installed in the installation hole. A through-hole 40 for passing the optical fiber line 50 is provided in the sealing plug 4, and the optical fiber line 50 passes through the through-hole 40. Further, in this embodiment, to seal the gap between the through-hole 40 and the optical fiber line 50, a sealing material is filled in the gap between the through-hole 40 and the optical fiber line 50, and the gap between the through-hole 40 and the optical fiber line 50 is sealed by the sealing material. After the sealing material is cured, it is blocked in the through-hole 40. Further, the sealing plug 4 in this embodiment has a stepped columnar structure. The sealing plug 4 includes a large-diameter end and a small-diameter end. The small-diameter end of the sealing plug 4 is inserted into the installation hole, and the outer wall of the small-diameter end is sealed with the installation hole by a sealing adhesive. Further, in this embodiment, four or more optical fiber temperature and strain sensors 5 can also be installed through the same sealing plug 4, and the through-hole 40 in the sealing plug 4 can be set to be able to pass multiple optical fiber lines 50 as needed. Further, the sealing plug 4 and the sealing of the installation hole in this embodiment can also ensure that no cement slurry leaks out during the process of injecting cement slurry into the simulated annulus 3. In addition, other methods can also be used to ensure that no cement slurry leaks out during the process of injecting cement slurry into the simulated annulus 3.

[0100] Further, as Figure 7 shown, in this embodiment, in order to make the large-diameter end of the sealing plug 4 closely fit on the outer side wall of the simulated formation 1, in this embodiment, an arc relief groove 41 is provided between the large-diameter end and the small-diameter end of the sealing plug 4. The arc relief groove 41 is recessed toward the large-diameter end of the sealing plug 4, and the arc relief groove 41 can be adapted to closely fit on the outer side wall of the simulated formation 1.

[0101] Further, as Figure 7 shown, in this embodiment, in order to ensure that the small-diameter end of the sealing plug 4 extends into the simulated annulus 3 and forms a smooth curved surface with the inner wall of the simulated formation 1, an arc recessed groove 42 is provided at the end of the small-diameter end of the sealing plug 4. The arc recessed groove 42 is recessed toward the small-diameter end of the sealing plug 4, and the arc radian of the arc recessed groove 42 is equal to the arc radian of the inner wall of the simulated formation 1. The arc recessed groove 42 of the sealing plug 4 is flush with the inner wall of the simulated formation 1, and the arc recessed groove 42 of the sealing plug 4 and the inner wall of the simulated formation 1 form a smooth curved surface. Further, the installation hole in this embodiment is a threaded hole, and an external thread is provided on the outer side wall of the small-diameter end of the sealing plug 4. The small-diameter end of the sealing plug 4 is threadedly connected in the installation hole. In addition, the installation hole can also be set as a smooth hole, and the small-diameter end of the sealing plug 4 is connected to the installation hole by interference fit.

[0102] It should be noted that in order to simulate the working conditions of an oil and gas well, the installation holes provided on the simulated formation 1 can also be sealed by other means, so that the simulation device for simulating the working conditions of an oil and gas well can realistically simulate the oil and gas well; in addition, the fiber optic temperature and strain sensor 5 can also be installed in the simulated annulus 3 by other means. For example, between the simulated casings 2 installed in the hollow columnar cavity of the simulated formation 1, first install the fiber optic temperature and strain sensor 5 on the inner side of the simulated formation 1, and then drill a through hole that can pass the fiber optic line 50 along the thickness direction of the simulated formation 1 near the installed fiber optic temperature and strain sensor 5. Pass the fiber optic line 50 through the through hole and seal the through hole, and then install the simulated casing 2 in the hollow columnar cavity of the simulated formation 1; in short, as long as it can be ensured that the simulation device can simulate the working conditions of an oil and gas well.

[0103] An embodiment of the present invention is as Figures 1 to 6 shown, the temperature and strain measurement device includes a fiber optic temperature and strain sensor 5;

[0104] The simulation device for measuring the temperature and strain of the cement sheath of an oil and gas well further includes:

[0105] A signal processing system 6, the fiber optic temperature and strain sensor 5 is electrically connected to the signal processing system 6 through a fiber optic line 50, or the fiber optic temperature and strain sensor 5 is wirelessly communicatively connected to the signal processing system 6.

[0106] In this embodiment, the temperature and strain measurement device includes a fiber optic temperature and strain sensor 5. The fiber optic temperature and strain sensor 5 measures the Bragg wavelength spectrum of the internal transmission grating to realize the measurement of the temperature and strain parameters of the cement sheath 7. The fiber optic temperature and strain sensor 5 has the characteristics of real-time and non-destructive measurement. At the same time, the fiber optic temperature and strain sensor 5 can also be designed into any shape. Therefore, the shape of the fiber optic temperature and strain sensor 5 can be changed according to the measurement position requirements, which is convenient for the fiber optic temperature and strain sensor 5 to accurately measure the cement sheath 7; further, the fiber optic temperature and strain sensor 5 has the ability to resist harsh environments including high temperatures and chemical erosion, can be measured in a variety of harsh environments and is beneficial to ensuring the reliability of the measurement. Further, the fiber optic temperature and strain sensor 5 is electrically connected to the signal processing system 6 through the fiber optic line 50, or the fiber optic temperature and strain sensor 5 is wirelessly communicatively connected to the signal processing system 6, which is convenient for real-time and continuous measurement of the temperature and strain states of the cement sheath 7 during the solidification process and subsequent drilling, completion and production processes.

[0107] In this embodiment, the fiber optic temperature and strain sensor 5 includes a fiber optic temperature sensor and a fiber optic strain sensor. The fiber optic temperature sensor and the fiber optic strain sensor are combined or formed into the fiber optic temperature and strain sensor 5 in other ways. The fiber optic temperature sensor and the fiber optic strain sensor are respectively electrically connected to the signal processing system 6 through a fiber optic cable 50, and transmit measurement signals to the signal processing system 6 through the fiber optic cable 50 respectively. During the measurement process by the fiber optic temperature sensor and the fiber optic strain sensor, turn on the signal processor, open the measurement program of the signal processor, set the wavelength zero points of the signals measured by the temperature fiber optic sensor and the strain fiber optic sensor, set the storage location of the measurement data, click start acquisition, and the fiber optic sensors immediately start to collect the strain and temperature during the setting process of the cement slurry. The obtained measurement data is subsequently copied to a computer for subsequent data processing. Further, during the measurement process of the strain sensor, correction can be performed through the data of the temperature sensor, thereby eliminating the influence of temperature change on the strain, and the strain state of the cement sheath 7 only under the action of the pressure load can be obtained. Further, the temperature and strain measurement device in this embodiment can also use other temperature and strain measurement instruments capable of measuring temperature and strain. It should be noted that the specific structures of the fiber optic temperature sensor and the fiber optic strain sensor in this embodiment can refer to the existing technologies in this field. In this embodiment, Figures 1 to 6 only the installation positions of the fiber optic temperature sensor and the fiber optic strain sensor are schematically shown.

[0108] In addition, except for the technical solutions disclosed in this embodiment, for other components of the fiber optic temperature sensor, fiber optic strain sensor, simulation device, signal processing system 6 and their working principles in the present invention, reference can be made to the conventional technical solutions in this technical field, and these conventional technical solutions are not the focus of the present invention, and the present invention will not be described in detail here.

[0109] In the present invention, the term "plurality" refers to two or more, unless otherwise clearly defined. Terms such as "installation", "connection", "connection", "fixation" and other terms should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; "connection" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0110] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "upper", "lower", "front", "rear", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or unit referred to must have a specific direction, be constructed and operated in a specific orientation, and therefore, it cannot be understood as a limitation to the present application.

[0111] In the description of this specification, the descriptions of the terms "one embodiment", "some embodiments", "specific embodiments", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or instance. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0112] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A method for measuring the temperature and strain of the cement sheath in an oil and gas well, characterized in that, Including: Establish a simulation device for simulating the working conditions of an oil and gas well, and form a simulated annulus for injecting cement slurry in the simulation device; wherein, the simulation device includes a simulated formation and a simulated casing, and a simulated annulus is defined between the simulated formation and the simulated casing; Select measurement points to be measured for temperature and strain in the simulated annulus, and preset temperature and strain measurement devices capable of measuring temperature and strain at the measurement points to be measured; wherein, multiple measurement points to be measured are selected in the vertical direction, and the multiple measurement points to be measured are spaced apart in the vertical direction, and temperature and strain measurement devices are respectively preset at the selected multiple measurement points to be measured; multiple measurement points to be measured are selected in the circumferential direction, multiple measurement points to be measured are respectively selected on different height planes of the simulated annulus, the multiple measurement points to be measured located on the same height plane are circumferentially spaced apart, and the radial distances from the multiple measurement points to be measured located on the same height plane to the vertical center of the simulated annulus are not equal, and temperature and strain measurement devices are respectively preset at the multiple measurement points to be measured, and the distances from the multiple temperature and strain measurement devices located on the same height plane to the vertical center of the simulated annulus in the circumferential direction are not equal; Inject cement slurry into the simulated annulus, and the cement slurry fills the simulated annulus to form a cement sheath; Measure the temperature and strain of the measurement points to be measured during the solidification process of the cement sheath through the temperature and strain measurement devices, collect the temperature and strain of the measurement points to be measured during the solidification process of the cement sheath, and obtain the temperature data and strain data of the measurement points to be measured during the solidification process of the cement sheath; It also includes: There is an installation hole in the simulated formation near the measurement point to be measured along the thickness direction of the simulated formation, the installation hole penetrates the simulated formation and communicates with the simulated annulus, and the temperature and strain measurement device is installed in the installation hole and the temperature and strain measurement device extends into the simulated annulus; By measuring the temperature and strain of the measurement points to be measured during the solidification process of the cement sheath through the temperature and strain measurement devices, the temperature and strain at any position including the inside, outer wall and inner wall of the cement sheath can be obtained; It also includes: Preset the curing temperature and curing pressure, regulate the temperature and pressure of the cement sheath according to the preset curing temperature and curing pressure, and the cement sheath is cured under the preset curing temperature and curing pressure until the curing is completed; Regulate the temperature and pressure of the cured cement sheath, measure the temperature and strain of the measurement points to be measured on the cement sheath under the current temperature and pressure conditions through the temperature and strain measurement devices, collect the temperature and strain of the cement sheath under the current temperature and pressure conditions, and obtain the temperature data and strain data of the measurement points to be measured on the cement sheath under the current temperature and pressure conditions.

2. The method for measuring the temperature and strain of the cement sheath of an oil and gas well according to claim 1, characterized in that, During the curing process of the cement sheath under the preset curing temperature and curing pressure, measure the temperature and strain of the measurement points to be measured during the curing process of the cement sheath through the temperature and strain measurement devices, collect the temperature and strain of the measurement points to be measured during the curing process of the cement sheath, and obtain the temperature data and strain data of the measurement points to be measured during the curing process of the cement sheath.

3. The method for measuring the temperature and strain of the cement sheath in an oil and gas well according to claim 1, wherein The regulation of the temperature and pressure of the cured cement sheath is specifically: regulate the temperature and pressure of the cured cement sheath according to the temperature and pressure conditions during the well completion process of the actual cement sheath after curing in the oil and gas well.

4. The method for measuring the temperature and strain of the cement sheath of an oil and gas well according to claim 1, characterized in that, According to the preset number of pressure application cycles under the cyclic pressure condition during the well completion process after the actual cement sheath curing is completed, during the process of regulating the pressure of the cured cement sheath, the cement sheath is cyclically pressurized according to the preset number of pressure application cycles until the number of cycles is completed.

5. The method for measuring the temperature and strain of the cement sheath in an oil and gas well according to claim 1, characterized in that, It further includes: According to the temperature and pressure conditions during the production process of the actual cement sheath after well completion in the oil and gas well, the temperature and pressure of the cement sheath after well completion are regulated. And according to the cyclic pressure condition during the production process of the actual cement sheath after well completion in the oil and gas well, the preset number of pressure application cycles is set. During the process of regulating the pressure of the cement sheath after well completion, the cement sheath is cyclically pressurized according to the preset number of pressure application cycles until the number of cycles is completed.

6. The method for measuring the temperature and strain of the cement sheath in an oil and gas well according to claim 1, wherein A columnar hollow cavity is provided in the simulated formation, and the simulated casing is vertically inserted into the columnar hollow cavity, and the simulated casing is coaxial with the simulated formation.

7. The method for measuring the temperature and strain of a cement sheath in an oil and gas well according to any one of claims 1 to 6, characterized in that, An optical fiber temperature and strain sensor is used as the temperature and strain measurement device, and the optical fiber temperature and strain sensor is electrically connected to the signal processing system through an optical fiber line, or the optical fiber temperature and strain sensor is wirelessly communicatively connected to the signal processing system.

8. The method for measuring the temperature and strain of the cement sheath of an oil and gas well according to any one of claims 1 to 6, characterized in that, It further includes: Combined with the elastic modulus of the cement slurry injected into the simulated annulus, the obtained strain data of the measurement point is brought into the calculation formula: Stress = Strain × Elastic Modulus, to calculate and obtain the stress data of the measurement point.

9. A simulation device for measuring the temperature and strain of a cement sheath in an oil and gas well, characterized in that, It includes: A simulated formation, in which a columnar hollow cavity is provided; A simulated casing, vertically inserted into the columnar hollow cavity, the simulated formation is coaxial with the simulated device, and a simulated annulus for injecting cement slurry is defined between the simulated formation and the simulated casing; measurement points for measuring temperature and strain are selected in the simulated annulus; A temperature and strain measurement device, arranged in the simulated annulus. When cement slurry is injected into the simulated annulus, the cement slurry fills the simulated annulus to form a cement sheath. The temperature and strain measurement device is in contact with the cement sheath and can measure the temperature and strain of the cement sheath. An installation hole is provided on the simulated formation along the thickness direction of the simulated formation, the installation hole penetrates the simulated formation and communicates with the simulated annulus, and the temperature and strain measurement device is installed in the installation hole and extends into the simulated annulus; the temperature and strain measurement device includes an optical fiber temperature and strain sensor; There are multiple temperature and strain measurement devices, and the multiple temperature and strain measurement devices are arranged at intervals in the vertical direction; multiple temperature and strain measurement devices are respectively arranged at circumferential intervals on different height planes of the simulated annulus. The multiple measurement points on the same height plane are arranged at circumferential intervals, and the distances from the multiple temperature and strain measurement devices on the same height plane to the vertical center of the simulated annulus are not equal; by measuring the temperature and strain of the measurement points during the solidification process of the cement sheath through the temperature and strain measurement device, the temperature and strain at any position including the inside, outer wall, and inner wall of the cement sheath can be obtained; The simulation device further includes: A signal processing system, the optical fiber temperature and strain sensor is electrically connected to the signal processing system through an optical fiber line, or the optical fiber temperature and strain sensor is wirelessly communicatively connected to the signal processing system.

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