A system and method for testing wellbore sealing integrity

Abstract

The present invention discloses a system and method for testing the sealing integrity of a wellbore, including: a sealing test device, which is used to implement a gas channeling test for simulating the complex working conditions of the wellbore after sealing the wellbore annulus; a strain acquisition device, which is used to synchronously acquire optical fiber feedback signals that characterize the stress change characteristics of each component of the wellbore in different directions during the gas channeling test; a demodulation processing device, which is connected to the strain acquisition device through an optical fiber cable, and is used to receive and demodulate the optical fiber feedback signal, and then determine the dynamic stress data corresponding to each component in different directions; a sealing analysis device, which is used to analyze the sealing failure mechanism that produces the current gas channeling phenomenon based on the dynamic stress data. The present invention can measure parameters such as multi-directional and multi-point strain and temperature changes of the wellbore in real time, continuously and accurately, and monitor and evaluate the sealing integrity of the wellbore under various complex conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of wellbore parameter testing, and in particular to a system and method for testing wellbore sealing integrity. Background Art

[0002] In recent years, the development of unconventional oil and gas has become a hot spot in the domestic oil industry. Since unconventional oil and gas (shale oil, shale gas, tight sandstone oil, tight sandstone gas, etc.) belong to low-porosity and low-permeability reservoirs, large-scale hydraulic fracturing is required to achieve economical and efficient exploitation. The fracturing construction load causes the wellbore to be subjected to alternating stress, which may cause damage to the cement ring and casing, cause seal failure, lead to interlayer gas channeling and annular pressure, etc., thus affecting the safe and efficient production of oil and gas. Gas storage plays an important role in peak regulation of natural gas consumption, and the periodic strong injection and strong production of gas storage also brings cyclic loads to the wellbore of the gas storage and temperature stress caused by temperature changes, which may damage the integrity of the wellbore and lead to a decrease in the recovery rate. Therefore, it is crucial to accurately test the parameters of the oil and gas wellbore under actual complex working conditions and evaluate the sealing integrity of the wellbore, so as to provide a scientific basis and guidance for studying the sealing failure mechanism of the wellbore under complex stress and proposing improvement measures.

[0003] In order to evaluate the sealing integrity of the wellbore, various research institutions have designed cement ring sealing evaluation devices in recent years. These devices can test the sealing integrity phenomenon and laws of the cement ring, but they cannot accurately test the various parameters of the wellbore under complex conditions, so as to accurately evaluate and determine the damage of the wellbore. Even if some devices test the parameters of oil and gas wellbore, they usually use the method of sticking strain gauges on the wellbore wall and casing surface, but the resistance strain gauge is not resistant to high temperature, is easily affected by the environment, and is difficult to lay. Only one strain gauge can be arranged on one line, and the cable line is large in size, which is easy to affect the force of the simulated wellbore, and may cause the failure of the measuring point and unreliable data. Therefore, there is currently a lack of accurate testing solutions for oil and gas wellbore under complex stress conditions.

[0004] Therefore, the prior art needs to develop an oil and gas wellbore parameter testing experimental instrument and method that can accurately test the parameters of a simulated wellbore under complex conditions to evaluate the sealing integrity of the wellbore, etc. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a system for testing the sealing integrity of a wellbore, comprising: a sealing test device, which is used to implement a gas channeling phenomenon test for simulating complex working conditions of the wellbore after the wellbore annulus is sealed; a strain acquisition device, which is used to synchronously acquire optical fiber feedback signals representing stress change characteristics of various components of the wellbore in different directions during the implementation of the gas channeling phenomenon test; a demodulation processing device, which is connected to the strain acquisition device through an optical fiber cable, and is used to receive and demodulate the optical fiber feedback signal, and then determine the dynamic stress data corresponding to each component in different directions; a sealing analysis device, which is used to analyze the sealing failure mechanism that produces the current gas channeling phenomenon based on the dynamic stress data.

[0006] Preferably, the strain acquisition device comprises: a first circumferential sensor group of the casing, a second circumferential sensor group of the casing and an axial sensor group of the casing arranged at the outer wall of the casing, wherein each sensor in the first circumferential sensor group of the casing is located in the middle of the casing and is spaced apart in the circumferential direction, each sensor in the second circumferential sensor group of the casing is located at the end of the casing and is spaced apart in the circumferential direction, and each sensor in the axial sensor group of the casing is spaced apart in the axial direction of the casing; a first circumferential sensor group of the outer cylinder, a second circumferential sensor group of the outer cylinder and an axial sensor group of the outer cylinder arranged at the outer wall of the outer cylinder, wherein each sensor in the first circumferential sensor group of the outer cylinder is located The sensors are arranged in the middle of the outer cylinder and are spaced apart in the circumferential direction, the sensors in the second circumferential sensor group of the outer cylinder are located at the end of the outer cylinder and are spaced apart in the circumferential direction, and the sensors in the axial sensor group of the outer cylinder are spaced apart in the axial direction of the outer cylinder; and an annulus circumferential sensor group, an annulus radial sensor group and an annulus axial sensor group are arranged at the annulus support, wherein the annulus circumferential sensor group is located at the annulus support disk and is spaced apart in the circumferential direction of the disk, the annulus radial sensor group is located at the annulus support disk and is spaced apart in the specified radial direction of the disk, and the annulus axial sensor group is located at the annulus support leg and is spaced apart in the axial direction of the annulus.

[0007] Preferably, each sensor in the strain acquisition device is a fiber Bragg grating pressure sensor, wherein each sensor group calibrates the measuring points of each pressure sensor in the group through an optical fiber cable corresponding to the current sensor group.

[0008] Preferably, the demodulation processing device is also used to receive the optical fiber feedback signals transmitted by each sensor group representing different position and direction combination conditions in the strain acquisition device respectively when implementing the gas channeling phenomenon test based on temperature change, and demodulate them to obtain the dynamic stress data corresponding to the different position and direction combination conditions of the wellbore; the sealing analysis device is also used to judge whether the stress of each combination condition reaches the ultimate strength of the corresponding position based on the dynamic stress data corresponding to different optical fiber channels, so as to determine the cause of the current wellbore sealing failure, so as to associate the gas channeling data corresponding to the current test, the dynamic stress data of different optical fiber channels, and the cause of sealing failure to form the data, wherein the cause of sealing failure is interface junction damage or strength damage.

[0009] Preferably, the sealing analysis device is also used to identify the stress direction of the stress collection position that reaches the ultimate strength when strength damage is detected, so as to clarify the specific type of strength damage, so as to associate the gas channeling data corresponding to the current test, the dynamic stress data of different optical fiber channels, the cause of sealing failure, and the specific type of strength damage to form the information.

[0010] Preferably, the system further comprises: a temperature acquisition device for synchronously acquiring optical fiber feedback signals representing temperature variation characteristics at various components of the wellbore during the gas channeling phenomenon test.

[0011] Preferably, the temperature acquisition device comprises: a casing temperature sensor group arranged in the middle of the casing; an outer tube temperature sensor group arranged in the middle of the outer tube; and an annulus temperature sensor group arranged at the annulus support disc, wherein each sensor in the temperature acquisition device is a fiber grating temperature sensor, wherein each sensor group calibrates the measuring points of each temperature sensor in the group through an optical fiber cable corresponding to the current sensor group.

[0012] Preferably, the demodulation processing device is also used to receive and demodulate the optical fiber feedback signals transmitted by each sensor group representing different parts in the temperature acquisition device respectively when implementing the gas channeling phenomenon test including pressure changes, so as to obtain the dynamic temperature data corresponding to different positions of the wellbore, and to receive and demodulate the optical fiber feedback signals transmitted by each sensor group representing different position and direction combination conditions in the strain acquisition device respectively, so as to obtain the dynamic stress data corresponding to different position and direction combination conditions of the wellbore; the sealing analysis device is also used to correct the dynamic stress data corresponding to the different optical fiber channels according to the dynamic temperature data corresponding to the different optical fiber channels and the dynamic stress data corresponding to the different optical fiber channels, so as to filter out the first type of stress change characteristics caused by temperature changes in the measured stress data, so as to analyze the sealing failure mechanism of the current gas channeling phenomenon using the corrected dynamic stress data.

[0013] On the other hand, the present invention also provides a method for testing the sealing integrity of a wellbore, which is implemented using the system as described above, and the method includes: deploying a strain acquisition device; sealing the wellbore annulus, and then implementing a gas channeling phenomenon test for simulating complex working conditions of the wellbore; during the gas channeling phenomenon test, synchronously acquiring a fiber optic feedback signal that characterizes the stress change characteristics of each component of the wellbore in different directions; receiving the fiber optic feedback signal through a fiber optic cable and demodulating it, and then determining the dynamic stress data corresponding to each component in different directions; and analyzing the sealing failure mechanism that produces the current gas channeling phenomenon based on the dynamic stress data.

[0014] Preferably, the method further comprises: when implementing the gas channeling phenomenon test based on temperature change, respectively receiving the optical fiber feedback signals transmitted by each sensor group representing different position and direction combination conditions, and demodulating them to obtain the dynamic stress data corresponding to the different position and direction combination conditions of the wellbore; judging whether the stress of each combination condition reaches the ultimate strength of the corresponding position characteristic according to the dynamic stress data corresponding to different optical fiber channels, so as to determine the cause of the current wellbore sealing failure, so as to associate the gas channeling data corresponding to the current test, the dynamic stress data of different optical fiber channels, and the cause of sealing failure to form the data, wherein the cause of sealing failure is interface junction damage or strength damage.

[0015] Compared with the prior art, one or more embodiments of the above scheme may have the following advantages or beneficial effects:

[0016] The present invention discloses a system and method for testing the sealing integrity of a wellbore. The system and method use fiber grating sensor technology to arrange a multi-channel pressure sensor group and a multi-channel temperature sensor group at different parts and stress directions of the wellbore. In the process of testing the gas channeling phenomenon that simulates the complex working conditions of the wellbore, it can continuously and accurately measure the parameters such as multi-directional and multi-point strain and temperature change of the wellbore in real time, monitor and evaluate the sealing integrity of the wellbore under various complex conditions, and form a system to analyze the mechanical and temperature deformation laws to evaluate whether the various components of the wellbore are damaged, and reveal the failure mechanism of the sealing integrity of the wellbore, and further establish its quantitative judgment criteria, so as to provide a scientific basis and guidance for improving the sealing of oil and gas wellbores. In addition, the present invention also has the advantages of small size, high sensitivity, high temperature resistance, multi-directional testing, and one-line multi-point arrangement.

[0017] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0019] Figure 1 It is a schematic diagram of the overall structure of a system for testing the sealing integrity of a wellbore according to an embodiment of the present application.

[0020] Figure 2 It is a schematic diagram of the specific structure of a system for testing the sealing integrity of a wellbore according to an embodiment of the present application.

[0021] Figure 3 It is a schematic diagram of the sensor distribution characteristics in the system for testing the wellbore sealing integrity according to an embodiment of the present application.

[0022] Figure 4 1 is a step diagram of a method for testing wellbore sealing integrity according to an embodiment of the present application. DETAILED DESCRIPTION

[0023] The following will describe the implementation methods of the present invention in detail with reference to the accompanying drawings and embodiments, so that the implementation process of how the present invention applies technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly. It should be noted that as long as there is no conflict, the various embodiments of the present invention and the various features in the embodiments can be combined with each other, and the technical solutions formed are all within the protection scope of the present invention.

[0024] In addition, the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions. Also, although a logical sequence is shown in the flowchart, in some cases, the steps shown or described can be performed in a sequence different from that here.

[0025] In recent years, the development of unconventional oil and gas has become a hot spot in the domestic oil industry. Since unconventional oil and gas (shale oil, shale gas, tight sandstone oil, tight sandstone gas, etc.) belong to low-porosity and low-permeability reservoirs, large-scale hydraulic fracturing is required to achieve economical and efficient exploitation. The fracturing construction load causes the wellbore to be subjected to alternating stress, which may cause damage to the cement ring and casing, cause seal failure, lead to interlayer gas channeling and annular pressure, etc., thus affecting the safe and efficient production of oil and gas. Gas storage plays an important role in peak regulation of natural gas consumption, and the periodic strong injection and strong production of gas storage also brings cyclic loads to the wellbore of the gas storage and temperature stress caused by temperature changes, which may damage the integrity of the wellbore and lead to a decrease in the recovery rate. Therefore, it is crucial to accurately test the parameters of the oil and gas wellbore under actual complex working conditions and evaluate the sealing integrity of the wellbore, so as to provide a scientific basis and guidance for studying the sealing failure mechanism of the wellbore under complex stress and proposing improvement measures.

[0026] In order to evaluate the sealing integrity of the wellbore, various research institutions have designed cement ring sealing evaluation devices in recent years. These devices can test the sealing integrity phenomenon and laws of the cement ring, but they cannot accurately test the various parameters of the wellbore under complex conditions, so as to accurately evaluate and determine the damage of the wellbore. Even if some devices test the parameters of oil and gas wellbore, they usually use the method of sticking strain gauges on the wellbore wall and casing surface, but the resistance strain gauge is not resistant to high temperature, is easily affected by the environment, and is difficult to lay. Only one strain gauge can be arranged on one line, and the cable line is large in size, which is easy to affect the force of the simulated wellbore, and may cause the failure of the measuring point and unreliable data. Therefore, there is currently a lack of accurate testing solutions for oil and gas wellbore under complex stress conditions.

[0027] Therefore, in order to solve one or more of the above technical problems, the present application proposes a system and method for testing the sealing integrity of a wellbore. The system and method include: a sealing test device for implementing a gas channeling test under simulated complex working conditions of the wellbore; a strain acquisition device for synchronously acquiring the optical fiber feedback signal that characterizes the stress change characteristics of each component of the wellbore in different directions using optical fiber sensing technology during the gas channeling test; a demodulation processing device for receiving the optical fiber feedback signal through an optical fiber cable and demodulating it to obtain the dynamic stress data corresponding to each component in different directions; and a sealing analysis device for analyzing the sealing failure mechanism that generates the current gas channeling phenomenon based on the dynamic stress data. In this way, the present invention can accurately measure the wellbore parameters (such as stress strain and / or temperature change) required for the test process by using optical fiber grating sensing technology during the test of the gas channeling phenomenon under different working conditions, thereby obtaining accurate sealing failure mechanism analysis results, so as to use the analysis results to form data for studying the sealing failure mechanism under the complex working environment of the wellbore.

[0028] Figure 1 Schematic diagram of the overall structure of the system for testing the wellbore sealing integrity according to the embodiment of the present application. Figure 1 As shown, the system for testing the wellbore sealing integrity of the present invention (hereinafter referred to as “wellbore sealing integrity testing system”) at least includes: a sealing testing device 10, a strain acquisition device 20, a demodulation processing device 30 and a sealing analysis device 40.

[0029] Specifically, the sealing test device 10 is used to perform a gas channeling test for simulating the complex working conditions of the wellbore after the wellbore annulus is sealed. In an embodiment of the present invention, the sealing test device 10 is used as an execution device for the gas channeling test, and needs to perform a sealing operation on the wellbore annulus through a sealing detection system, and then pressurize the casing according to the corresponding simulation strategy (according to a pre-designed pressurization strategy, the pressurization strategy includes target pressure, pressurization time, holding time, number of cycles, etc.) and / or heat (according to a pre-designed heating strategy, the heating strategy includes multiple target temperatures, the holding time of each target temperature, the realization order of each target temperature, the number of cycles, etc.) to simulate different actual working environment states of the wellbore using the corresponding pressurization strategy and / or heating strategy, so as to prompt the sealing detection system to find that the sealed cement slurry has gas channeling, thereby recording the gas channeling data of the simulation strategy (including: pressurization strategy and / or heating strategy) corresponding to the current gas channeling phenomenon, thereby completing a single gas channeling phenomenon test. Among them, the gas channeling data includes but is not limited to information such as gas channeling position, gas channeling direction and gas channeling speed.

[0030] The strain acquisition device 20 is used to synchronously acquire optical fiber feedback signals representing stress change characteristics of various components of the wellbore in different directions during the gas channeling test. In actual application, since the wellbore includes three parts: casing, outer tube and cement ring, the embodiment of the present invention uses the strain acquisition device 20 to synchronously acquire signals representing dynamic stress change characteristics of casing, outer tube and cement ring in different directions by using fiber grating sensing technology during a single gas channeling test, so as to accurately obtain the dynamic stress change characteristics in an underground environment with high temperature, high pressure, unstable change and other characteristics.

[0031] The demodulation processing device 30 is connected via an optical fiber cable (optical fiber line, reference Figure 3 ①) is connected to the strain acquisition device 20. The demodulation processing device 30 is used to receive the multi-channel optical fiber feedback signals collected by the strain acquisition device 20, and demodulate the received multi-channel optical fiber feedback signals, and then determine the dynamic stress data corresponding to each component in different directions. In the demodulation processing device 30, not only the optical fiber feedback signals representing the dynamic change characteristics of the stress corresponding to different directions at the three parts of the casing, outer tube and cement ring are received, but also the received optical fiber feedback signals are converted into stress data that is easy to analyze, so as to obtain the dynamic stress data corresponding to each component in different directions based on each moment.

[0032] The sealing analysis device 40 is connected to the demodulation processing device 30. The sealing analysis device 40 is used to analyze the sealing failure mechanism that produces the current gas channeling phenomenon based on the dynamic stress data obtained from the demodulation processing device 30, so as to use the analysis results obtained from the gas channeling phenomenon tests that are used to simulate different downhole environmental conditions for many times, thereby forming data that can study the sealing failure mechanism under the complex working environment of the wellbore. In this way, the present invention is more conducive to further quantitatively establishing the judgment criteria for the degree of influence of the changing characteristics of different downhole environmental states on the sealing integrity of the wellbore by collecting the sealing failure mechanisms analyzed by the gas channeling phenomenon tests based on the downhole environment simulation for many times, so as to provide a scientific basis and guidance for improving the sealing of oil and gas wellbores.

[0033] It should be noted that, in the embodiment of the present invention, before starting to seal the wellbore annulus, it is necessary to arrange the strain acquisition device 20, the temperature acquisition device 50 described below, the demodulation processing device 30 and the sealing analysis device 40. After the installation and arrangement are completed, the wellbore annulus is further sealed by a series of steps such as injecting cement slurry into the annulus, heating and curing, gas injection protection and sealing detection.

[0034] Figure 2 Schematic diagram of the structure of the system for testing the sealing integrity of the wellbore according to the embodiment of the present application. Figure 2, the functions and structures of each device of the wellbore sealing integrity system described in the embodiment of the present invention are described in detail.

[0035] like Figure 2 As shown, the strain collection device 20 includes a casing feature collection device arranged at the outer wall of the casing, an outer cylinder feature collection device arranged at the outer wall of the outer cylinder, and a cement ring feature collection device arranged at the annulus support in the cement ring.

[0036] Figure 3 It is a schematic diagram of the sensor distribution characteristics in the system for testing the wellbore sealing integrity according to an embodiment of the present application.

[0037] like Figure 3 As shown, the casing feature acquisition device includes: a casing first circumferential sensor group 21, a casing second circumferential sensor group 22 and a casing axial sensor group 23. Among them, the casing first circumferential sensor group 21 (each sensor therein) is located at a specified depth position in the middle of the casing, and the sensors in the casing first circumferential sensor group 21 are spaced apart along the circumferential direction at the current depth position. The casing second circumferential sensor group 22 (each sensor therein) is located at a specified depth position at the end of the casing, and the sensors in the casing second circumferential sensor group 22 are spaced apart along the circumferential direction at the current depth position. The sensors in the casing axial sensor group 23 are spaced apart along the axial direction of the casing.

[0038] like Figure 3 As shown, the outer cylinder feature acquisition device includes: an outer cylinder first circumferential sensor group 24, an outer cylinder second circumferential sensor group 25 and an outer cylinder axial sensor group 26. Among them, the outer cylinder first circumferential sensor group 24 (each sensor therein) is located at a specified depth position in the middle of the outer cylinder, and each sensor in the outer cylinder first circumferential sensor group 24 is spaced apart along the circumferential direction at the current depth position. The outer cylinder second circumferential sensor group 25 (each sensor therein) is located at a specified depth position at the end of the outer cylinder, and each sensor in the outer cylinder second circumferential sensor group 25 is spaced apart along the circumferential direction at the current depth position. Each sensor in the outer cylinder axial sensor group 26 is spaced apart along the axial direction of the outer cylinder.

[0039] like Figure 3As shown, the cement sheath feature acquisition equipment includes: an annular circumferential sensor group 27, an annular radial sensor group 28 and an annular axial sensor group 29. Among them, the annular circumferential sensor group 27 is located at the disk in the annular support, and the sensors in the annular circumferential sensor group 27 are spaced apart along the circumferential direction of the disk. The annular radial sensor group 28 is located at the disk in the annular support, and the sensors in the annular radial sensor group 28 are spaced apart along the specified radial direction of the disk. In the embodiment of the present invention, the annular radial sensor group 28 can be set as one group or multiple groups, wherein each group of annular radial sensor groups 28 corresponds to a different radial direction. The annular axial sensor group 29 is located at the leg position in the annular support, and the sensors in the annular axial sensor group 29 are spaced apart along the axial direction of the current leg component.

[0040] Further, in the embodiment of the present invention, each sensor in the strain acquisition device 20 is a fiber Bragg grating pressure sensor (refer to Figure 3 ② in it). Among them, each sensor group calibrates the measuring points of each pressure sensor in the (current) group through the optical fiber cable corresponding to the current sensor group. Specifically, the optical fiber cable described in the embodiment of the present invention selects a cable with a wavelength range of 1535-1560nm, a bare fiber outer diameter of 0.25mm and a reflectivity of ≥95%. The fiber grating pressure and (described below) temperature sensors described in the embodiment of the present invention are both selected with a wavelength interval of 5nm and a grating area of ​​10mm silicon powder.

[0041] Further, the first circumferential sensor group 21 of the casing is connected to the demodulation processing device 30 through the first optical fiber cable. The first circumferential sensor group 21 of the casing is composed of a plurality of pressure sensors, each of which is a fiber Bragg grating pressure sensor. The first circumferential sensor group 21 of the casing is used to synchronously collect the fiber feedback signal (first channel fiber feedback signal) representing the circumferential stress change characteristics at the middle position of the casing during the implementation of the gas channeling phenomenon test, so that the demodulation processing device 30 can obtain the dynamic stress data used to represent the circumferential stress change characteristics at the middle position of the casing, which is recorded as the first channel dynamic stress data. The fiber Bragg grating pressure sensors in the first circumferential sensor group 21 of the casing are calibrated by the first optical fiber cable. In this way, not only can the fiber Bragg grating pressure sensors in the first circumferential sensor group 21 of the casing be connected by the first optical fiber cable, but also the stress characteristics corresponding to each measuring point calibrated by the first optical fiber cable are transmitted to the demodulation processing device 30 through the optical feedback signal for demodulation, forming the dynamic stress data corresponding to the first channel.

[0042] Further, the second circumferential sensor group 22 of the casing is connected to the demodulation processing device 30 through a second optical fiber cable. The second circumferential sensor group 22 of the casing is composed of a plurality of pressure sensors, each of which is a fiber Bragg grating pressure sensor. The second circumferential sensor group 22 of the casing is used to synchronously collect the fiber feedback signal (second channel fiber feedback signal) representing the circumferential stress change characteristics at the end (bottom) position of the casing during the implementation of the gas channeling phenomenon test, so that the demodulation processing device 30 can obtain the dynamic stress data used to represent the circumferential stress change characteristics at the end (bottom) position of the casing, which is recorded as the second channel dynamic stress data. The fiber Bragg grating pressure sensors in the second circumferential sensor group 22 of the casing are calibrated at the measuring point through the second optical fiber cable. In this way, not only can the fiber Bragg grating pressure sensors in the second circumferential sensor group 22 of the casing be connected by the second optical fiber cable, but also the stress characteristics corresponding to each measuring point calibrated by the second optical fiber cable are transmitted to the demodulation processing device 30 through the optical feedback signal for demodulation, forming the dynamic stress data corresponding to the second channel.

[0043] Further, the casing axial sensor group 23 is connected to the demodulation processing device 30 through a third optical fiber cable. The casing axial sensor group 23 is composed of a plurality of pressure sensors, each of which is a fiber Bragg grating pressure sensor. The casing axial sensor group 23 is used to synchronously collect the fiber feedback signal (third channel fiber feedback signal) representing the axial stress change characteristics of the position between the middle and the end of the casing during the implementation of the gas channeling phenomenon test, so that the demodulation processing device 30 can obtain the dynamic stress data used to represent the axial stress change characteristics of the position between the middle and the end of the casing, which is recorded as the third channel dynamic stress data. The fiber Bragg grating pressure sensors in the casing axial sensor group 23 are calibrated by the third optical fiber cable. In this way, not only can the fiber Bragg grating pressure sensors in the casing axial sensor group 23 be connected by the third optical fiber cable, but also the stress characteristics corresponding to each measuring point calibrated by the third optical fiber cable are transmitted to the demodulation processing device 30 through the optical feedback signal for demodulation, forming the dynamic stress data corresponding to the third channel.

[0044] Further, the first circumferential sensor group 24 of the outer cylinder is connected to the demodulation processing device 30 through the fourth optical fiber cable. The first circumferential sensor group 24 of the outer cylinder is composed of a plurality of pressure sensors, each of which is a fiber Bragg grating pressure sensor. The first circumferential sensor group 24 of the outer cylinder is used to synchronously collect the fiber feedback signal (the fourth channel fiber feedback signal) representing the circumferential stress change characteristics at the middle position of the outer cylinder during the implementation of the gas channeling phenomenon test, so that the demodulation processing device 30 can obtain the dynamic stress data used to represent the circumferential stress change characteristics at the middle position of the outer cylinder, which is recorded as the fourth channel dynamic stress data. The fiber Bragg grating pressure sensors in the first circumferential sensor group 24 of the outer cylinder are calibrated at the measuring point through the fourth optical fiber cable. In this way, not only can the fiber Bragg grating pressure sensors in the first circumferential sensor group 24 of the outer cylinder be connected by the fourth optical fiber cable, but also the stress characteristics corresponding to each measuring point calibrated by the fourth optical fiber cable are transmitted to the demodulation processing device 30 through the optical feedback signal for demodulation, so as to form the dynamic stress data corresponding to the fourth channel.

[0045] Further, the outer cylinder second circumferential sensor group 25 is connected to the demodulation processing device 30 through the fifth optical fiber cable. The outer cylinder second circumferential sensor group 25 is composed of a plurality of pressure sensors, each of which is a fiber Bragg grating pressure sensor. The outer cylinder second circumferential sensor group 25 is used to synchronously collect the fiber feedback signal (fifth channel fiber feedback signal) representing the circumferential stress change characteristics at the end (bottom) position of the outer cylinder during the gas channeling phenomenon test, so that the demodulation processing device 30 can obtain the dynamic stress data used to represent the circumferential stress change characteristics at the end (bottom) position of the outer cylinder, which is recorded as the fifth channel dynamic stress data. The fiber Bragg grating pressure sensors in the outer cylinder second circumferential sensor group 25 are calibrated by the fifth optical fiber cable. In this way, not only can the fiber Bragg grating pressure sensors in the outer cylinder second circumferential sensor group 25 be connected by the fifth optical fiber cable, but also the stress characteristics corresponding to each measuring point calibrated by the fifth optical fiber cable are transmitted to the demodulation processing device 30 through the optical feedback signal for demodulation, forming the dynamic stress data corresponding to the fifth channel.

[0046] Further, the outer cylinder axial sensor group 26 is connected to the demodulation processing device 30 through the sixth optical fiber cable. The outer cylinder axial sensor group 26 is composed of a plurality of pressure sensors, each of which is a fiber Bragg grating pressure sensor. The outer cylinder axial sensor group 26 is used to synchronously collect the fiber feedback signal (sixth channel fiber feedback signal) representing the axial stress change characteristics of the position between the middle and the end of the outer cylinder during the gas channeling phenomenon test, so that the demodulation processing device 30 can obtain the dynamic stress data used to represent the axial stress change characteristics of the position between the middle and the end of the outer cylinder, which is recorded as the sixth channel dynamic stress data. The fiber Bragg grating pressure sensors in the outer cylinder axial sensor group 26 are calibrated by the sixth optical fiber cable. In this way, not only can the fiber Bragg grating pressure sensors in the outer cylinder axial sensor group 26 be connected by the sixth optical fiber cable, but also the stress characteristics corresponding to each measuring point calibrated by the sixth optical fiber cable are transmitted to the demodulation processing device 30 through the optical feedback signal for demodulation, so as to form the dynamic stress data corresponding to the sixth channel.

[0047] Further, the annular circumferential sensor group 27 is connected to the demodulation processing device 30 through the seventh optical fiber cable. The annular circumferential sensor group 27 is composed of a plurality of pressure sensors, each of which is a fiber Bragg grating pressure sensor. The annular circumferential sensor group 27 is used to synchronously collect the fiber feedback signal (the seventh channel fiber feedback signal) representing the circumferential stress change characteristics at the disk position of the annular support during the implementation of the gas channeling phenomenon test, so that the demodulation processing device 30 can obtain the dynamic stress data used to represent the circumferential stress change characteristics of the cement ring, which is recorded as the seventh channel dynamic stress data. The fiber Bragg grating pressure sensors in the annular circumferential sensor group 27 are calibrated for measuring points through the seventh optical fiber cable. In this way, not only can the fiber Bragg grating pressure sensors in the annular circumferential sensor group 27 be connected by the seventh optical fiber cable, but also the stress characteristics corresponding to each measuring point calibrated by the seventh optical fiber cable are transmitted to the demodulation processing device 30 through the optical feedback signal for demodulation, forming the dynamic stress data corresponding to the seventh channel.

[0048] Further, the annular radial sensor group 28 is connected to the demodulation processing device 30 through the eighth optical fiber cable. The annular radial sensor group 28 is composed of a plurality of pressure sensors, each of which is a fiber Bragg grating pressure sensor. The annular radial sensor group 28 is used to synchronously collect the optical fiber feedback signal (eighth channel optical fiber feedback signal) representing the radial stress change characteristics at the disk position of the annular support during the implementation of the gas channeling phenomenon test, so that the demodulation processing device 30 can obtain the dynamic stress data used to represent the radial stress change characteristics of the cement ring, which is recorded as the eighth channel dynamic stress data. The fiber Bragg grating pressure sensors in the annular radial sensor group 28 are calibrated at the measuring point through the eighth optical fiber cable. In this way, not only can the fiber Bragg grating pressure sensors in the annular radial sensor group 28 be connected by the eighth optical fiber cable, but also the stress characteristics corresponding to each measuring point calibrated by the eighth optical fiber cable are transmitted to the demodulation processing device 30 through the optical feedback signal for demodulation, forming the dynamic stress data corresponding to the eighth channel.

[0049] Further, the annular axial sensor group 29 is connected to the demodulation processing device 30 through the ninth optical fiber cable. The annular axial sensor group 29 is composed of a plurality of pressure sensors, each of which is a fiber Bragg grating pressure sensor. The annular axial sensor group 29 is used to synchronously collect the fiber feedback signal (ninth channel fiber feedback signal) representing the axial stress change characteristics at the leg position of the annular support during the implementation of the gas channeling phenomenon test, so that the demodulation processing device 30 can obtain the dynamic stress data used to represent the axial stress change characteristics of the cement ring, which is recorded as the ninth channel dynamic stress data. The fiber Bragg grating pressure sensors in the annular axial sensor group 29 are calibrated at the measuring points through the ninth optical fiber cable. In this way, not only can the fiber Bragg grating pressure sensors in the annular axial sensor group 29 be connected by the ninth optical fiber cable, but also the stress characteristics corresponding to each measuring point calibrated by the ninth optical fiber cable are transmitted to the demodulation processing device 30 through the optical feedback signal for demodulation, forming the dynamic stress data corresponding to the ninth channel.

[0050] Continue to refer Figure 2 The strain acquisition device 20 described in the embodiment of the present invention further includes a light source module (not numbered), wherein the light source module is connected to each optical fiber cable. The light source module is used to use the internal C-band module or C+L-band module to send the initial optical signal of the corresponding band to each sensor group through different optical fiber cables, and make each measuring point generate a corresponding feedback signal after responding to the initial optical signal, so that each cable transmits the optical fiber feedback signal (formed by superimposing the feedback signals of each measuring point in the corresponding sensor group) to the demodulation processing device 30.

[0051] Furthermore, the demodulation processing device 30 is also used to receive the optical fiber feedback signals transmitted by each sensor group representing different position and direction combination conditions in the strain acquisition device 20 respectively when implementing the gas channeling phenomenon test based on temperature change, and demodulate them to obtain the corresponding dynamic stress data under different position and direction combination conditions of the wellbore. Specifically, in the embodiment of the present invention, when the sealing test device 10 only implements the gas channeling phenomenon test of the simulation strategy including only the heating strategy (that is, after the wellbore annulus is sealed, only the actual working environment downhole is simulated by performing the heating operation to realize the current gas channeling phenomenon test), the demodulation processing device 30 is used to receive the optical fiber feedback signal representing the circumferential stress change characteristics of the middle part of the casing, the optical fiber feedback signal representing the circumferential stress change characteristics of the casing end, the optical fiber feedback signal representing the axial stress change characteristics of the casing, and the optical fiber feedback signal representing the circumferential stress change characteristics of the middle part of the outer tube respectively through each (the above-mentioned at least nine) optical fiber cable. The optical fiber feedback signal characterizing the circumferential stress change characteristics of the outer tube end, the optical fiber feedback signal characterizing the axial stress change characteristics of the outer tube, the optical fiber feedback signal characterizing the circumferential stress change characteristics of the cement ring, the optical fiber feedback signal characterizing the radial stress change characteristics of the cement ring, and the optical fiber feedback signal characterizing the axial stress change characteristics of the cement ring are demodulated in parallel, so as to obtain the corresponding dynamic stress data under different combinations of wellbore positions and directions for each channel (the dynamic stress data of each channel is composed of real-time stress data at each stress collection moment).

[0052] like Figure 2 As shown, the demodulation processing device 30 is composed of a plurality of processing channels with the same structure, and each processing channel is respectively connected to a corresponding optical fiber cable. Among them, each processing channel includes at least: a spectrum acquisition module 31, a demodulation module 32, a data analysis module 33 and a display module 34. The spectrum acquisition module 31 is used to collect the optical fiber feedback signal transmitted by the current optical fiber cable due to temperature changes, and then send the collected optical fiber feedback signal to the demodulation module 32. Then, the demodulation module 32 is used to receive the output signal of the spectrum acquisition module 31, and perform fiber Bragg grating demodulation on the received signal. The data analysis module 33 is used to analyze the demodulated signal, generate dynamic stress data corresponding to the combination conditions of the current specific part of the wellbore and the stress direction, so that the dynamic stress data of the current channel can be displayed by the display module 34.

[0053] Further, the sealing analysis device 40 is connected to the data analysis module 33 in each channel of the above-mentioned demodulation processing device 30. The sealing analysis device 40 is used to determine whether the real-time stress of each combination condition (the combination condition of the specific part of the wellbore and the stress direction corresponding to the corresponding channel) reaches the ultimate strength (casing ultimate strength, outer tube ultimate strength, cement ring ultimate tensile strength, cement ring ultimate compressive strength) at the installation position of the corresponding sensor group according to the dynamic stress data corresponding to the different optical fiber channels obtained, so as to determine the cause of the current wellbore sealing failure, so as to associate the gas channeling data corresponding to the current gas channeling phenomenon test, the dynamic stress data of different optical fiber channels, and the cause of sealing failure to form the above-mentioned data. Among them, in the embodiment of the present invention, the identifiable cause of sealing failure is interface junction damage or strength damage.

[0054] Specifically, the sealing analysis device 40 is also used to compare the real-time stress data in the dynamic stress data received by all channels related to the casing with the ultimate strength of the casing to determine whether the real-time stress of the casing reaches or exceeds its ultimate strength; compare the real-time stress data in the dynamic stress data received by all channels related to the outer tube with the ultimate strength of the outer tube to determine whether the real-time stress of the outer tube reaches or exceeds its ultimate strength; compare the real-time stress data in the dynamic stress data received by all channels related to the cement ring circumferentially or axially with the ultimate tensile strength of the cement ring to determine whether the real-time stress of the cement ring reaches or exceeds its ultimate tensile strength; compare the real-time stress data in the dynamic stress data received by all channels related to the cement ring radially with the ultimate compressive strength of the cement ring to determine whether the real-time stress of the cement ring reaches or exceeds its ultimate compressive strength. If none of the above four phenomena occur, the current sealing failure cause is determined to be interface junction damage. In addition, if the sealing analysis device 40 detects any of the above phenomena, the current sealing failure cause is determined to be strength damage.

[0055] Furthermore, when the sealing analysis device 40 detects that strength damage has occurred, the sealing analysis device 40 is also used to identify the stress direction of the stress collection position (sensor group installation position) that reaches (or exceeds) the ultimate strength, so as to clarify the specific type of strength damage. At this time, it is necessary to associate the gas channeling data corresponding to the current gas channeling phenomenon test, the dynamic stress data of different optical fiber channels, the cause of the sealing failure (strength damage), and the specific damage type causing the current strength damage together to form the above-mentioned data. Among them, in the embodiment of the present invention, the specific type of strength damage that can be identified is selected from one of tensile damage, compressive damage and tensile damage.

[0056] In the first embodiment, when identifying the specific type of strength damage, if the sealing analysis device 40 identifies that the stress direction corresponding to the stress collection position that currently reaches (or exceeds) the ultimate strength is circumferential stress, the specific type of the current strength damage is identified as tensile damage.

[0057] In the second embodiment, when identifying the specific type of strength damage, if the sealing analysis device 40 identifies that the stress direction corresponding to the stress collection position that currently reaches (or exceeds) the ultimate strength is radial stress, the specific type of the current strength damage is classified as compressive damage.

[0058] In the third embodiment, when identifying the specific type of strength damage, if the sealing analysis device 40 identifies that the stress direction corresponding to the stress collection position that currently reaches (or exceeds) the ultimate strength is axial stress, the specific type of the current strength damage is identified as tensile damage.

[0059] In addition, in the embodiment of the present invention, the wellbore sealing integrity testing system described above further includes: a temperature acquisition device 50 .

[0060] The temperature acquisition device 50 is used to synchronously acquire the optical fiber feedback signal representing the temperature change characteristics of each component of the wellbore during the gas channeling test. In actual application, since the wellbore includes three parts: casing, outer tube and cement ring, the embodiment of the present invention also uses the temperature acquisition device 50 to synchronously acquire the signals representing the temperature dynamic change characteristics of different wellbore components at the casing, outer tube and cement ring using fiber grating sensing technology during a single gas channeling test, so as to accurately obtain the temperature dynamic change characteristics in an underground environment with high temperature, high pressure, unstable change and other characteristics.

[0061] refer to Figure 2 The temperature acquisition device 50 includes: a casing temperature sensor group 51, an outer tube temperature sensor group 52 and an annulus temperature sensor group 53. The casing temperature sensor group 51 is arranged at the middle position of the casing, and is composed of one or more temperature sensors. The outer tube temperature sensor group 52 is arranged at the middle position of the outer tube, and is composed of one or more temperature sensors. The annulus temperature sensor group 53 is arranged at the disk of the annulus support, and is composed of one or more temperature sensors. Among them, each sensor in the temperature acquisition device is a fiber grating temperature sensor. At the same time, each temperature sensor group calibrates the measuring point of each temperature sensor in the (current) group through the optical fiber cable corresponding to the current temperature sensor group.

[0062] Specifically, further, the casing temperature sensor group 51 is connected to the demodulation processing device 30 through the tenth optical fiber cable. The casing temperature sensor group 51 is composed of a plurality of temperature sensors, each of which is a fiber Bragg grating temperature sensor. The casing temperature sensor group 51 is used to synchronously collect the fiber feedback signal (the tenth channel fiber feedback signal) representing the casing temperature change characteristics at the middle position of the casing during the implementation of the gas channeling phenomenon test, so that the demodulation processing device 30 can obtain the dynamic temperature data used to represent the temperature change characteristics at the middle position of the casing, which is recorded as the tenth channel dynamic temperature data. The fiber Bragg grating temperature sensors in the casing temperature sensor group 51 are calibrated at the measuring point through the tenth optical fiber cable. In this way, not only can the tenth optical fiber cable be used to connect the fiber Bragg grating temperature sensors in the casing temperature sensor group 51, but also the temperature characteristics corresponding to each measuring point calibrated by the tenth optical fiber cable are transmitted to the demodulation processing device 30 through the optical feedback signal for demodulation, so as to form the dynamic temperature data corresponding to the tenth channel.

[0063] Further, the outer cylinder temperature sensor group 52 is connected to the demodulation processing device 30 through the eleventh optical fiber cable. The outer cylinder temperature sensor group 52 is composed of a plurality of temperature sensors, each of which is a fiber Bragg grating temperature sensor. The outer cylinder temperature sensor group 52 is used to synchronously collect the fiber feedback signal (the eleventh channel fiber feedback signal) representing the temperature change characteristics of the outer cylinder at the middle position of the outer cylinder during the implementation of the gas channeling phenomenon test, so that the demodulation processing device 30 can obtain the dynamic temperature data used to represent the temperature change characteristics of the middle position of the outer cylinder, which is recorded as the eleventh channel dynamic temperature data. The fiber Bragg grating temperature sensors in the outer cylinder temperature sensor group 52 are calibrated at the measuring point through the eleventh optical fiber cable. In this way, not only can the fiber Bragg grating temperature sensors in the outer cylinder temperature sensor group 52 be connected by the eleventh optical fiber cable, but also the temperature characteristics corresponding to each measuring point calibrated by the eleventh optical fiber cable are transmitted to the demodulation processing device 30 through the optical feedback signal for demodulation, so as to form the dynamic temperature data corresponding to the eleventh channel.

[0064] Further, the annular temperature sensor group 53 is connected to the demodulation processing device 30 through the twelfth optical fiber cable. The annular temperature sensor group 53 is composed of a plurality of temperature sensors, each of which is a fiber Bragg grating temperature sensor. The annular temperature sensor group 53 is used to synchronously collect the fiber feedback signal (twelfth channel fiber feedback signal) representing the temperature change characteristics of the cement ring at the middle position of the cement ring during the implementation of the gas channeling phenomenon test, so that the demodulation processing device 30 can obtain the dynamic temperature data used to represent the temperature change characteristics of the middle position of the cement ring, which is recorded as the twelfth channel dynamic temperature data. The fiber Bragg grating temperature sensors in the annular temperature sensor group 53 are calibrated at the measuring point through the twelfth optical fiber cable. In this way, not only can the fiber Bragg grating temperature sensors in the annular temperature sensor group 53 be connected by the twelfth optical fiber cable, but also the temperature characteristics corresponding to each measuring point calibrated by the twelfth optical fiber cable are transmitted to the demodulation processing device 30 through the optical feedback signal for demodulation, forming the dynamic temperature data corresponding to the twelfth channel.

[0065] At this time, the demodulation processing device 30 is not only connected to the stress acquisition device 20, but also connected to the temperature acquisition device 50. The demodulation processing device 30 is also used to receive and demodulate the optical fiber feedback signals transmitted by the sensor groups representing different position and direction combination conditions in the strain acquisition device 20 when implementing the gas channeling phenomenon test based on pressure change, so as to obtain the dynamic stress data corresponding to the different position and direction combination conditions of the wellbore, and receive and demodulate the optical fiber feedback signals transmitted by the sensor groups representing different parts in the temperature acquisition device 50, so as to obtain the dynamic temperature data corresponding to different positions of the wellbore.

[0066] Specifically, in the embodiments of the present invention, due to the actual spaciousness and complexity of the underground, it is necessary to study not only the sealing failure mechanism of the gas channeling phenomenon caused by temperature changes, but also the sealing failure mechanism of the gas channeling phenomenon caused by pressure changes, and even more so the sealing failure mechanism of the gas channeling phenomenon caused by the combined changes of pressure and temperature. Therefore, in the embodiment of the present invention, when the sealing test device 10 implements a gas channeling phenomenon test that includes only a simulation strategy including a pressurization strategy (that is, after the wellbore annulus is sealed, only the pressurization operation is implemented to simulate the actual downhole working environment to achieve the current gas channeling phenomenon test), or when the sealing test device 10 implements a gas channeling phenomenon test that includes both heating and pressurization strategies (that is, after the wellbore annulus is sealed, the actual downhole working environment is simulated by heating and pressurization operations to achieve the current gas channeling phenomenon test), the demodulation processing device 30 is used to receive, through each (the above-mentioned at least twelve) optical fiber cables, an optical fiber feedback signal characterizing the circumferential stress change characteristics of the middle portion of the casing, an optical fiber feedback signal characterizing the circumferential stress change characteristics of the casing end portion, an optical fiber feedback signal characterizing the axial stress change characteristics of the casing, an optical fiber feedback signal characterizing the circumferential stress change characteristics of the middle portion of the outer tube, and an optical fiber feedback signal characterizing the circumferential stress change characteristics of the outer tube. The optical fiber feedback signal representing the circumferential stress change characteristics of the end, the optical fiber feedback signal representing the axial stress change characteristics of the outer tube, the optical fiber feedback signal representing the circumferential stress change characteristics of the cement ring, the optical fiber feedback signal representing the radial stress change characteristics of the cement ring, the optical fiber feedback signal representing the axial stress change characteristics of the cement ring, the optical fiber feedback signal representing the temperature change characteristics of the casing, the optical fiber feedback signal representing the temperature change characteristics of the outer tube, and the optical fiber feedback signal representing the temperature change characteristics of the cement ring are demodulated in parallel to obtain the optical fiber feedback signals collected by each channel, so as to obtain the corresponding dynamic stress data under different combinations of wellbore positions and directions for each channel (the dynamic stress data of each channel is composed of the real-time stress data at each stress collection moment) or the dynamic temperature data corresponding to different components of the wellbore (the dynamic temperature data of each channel is composed of the real-time temperature data at each temperature collection moment).

[0067] Continue as Figure 2As shown, in the embodiment of the present invention, when the sealing test device 10 implements the gas channeling phenomenon test of the simulation strategy including the pressurization strategy, each processing channel in the demodulation processing device 30 will be connected to a corresponding optical fiber cable. Among them, in each processing channel, the spectrum acquisition module 31 is used to collect the optical fiber feedback signal transmitted by the current optical fiber cable due to temperature and / or changes, so as to send the collected optical fiber feedback signal to the demodulation module 32; then, the demodulation module 32 is used to receive the output signal of the spectrum acquisition module 31, and perform fiber grating demodulation on the received signal; the data analysis module 33 is used to analyze the demodulated signal, generate dynamic stress data corresponding to the combination conditions of the current specific part of the wellbore and the stress direction, so that the display module 34 can display the dynamic stress data of the current channel, or generate dynamic temperature data corresponding to the component parts of the current wellbore, so that the display module 34 can display the dynamic temperature data of the current channel.

[0068] At this time, the sealing analysis device 40 connected to the data analysis module 33 in each channel in the demodulation processing device 30 is also used to correct the dynamic stress data corresponding to different optical fiber channels based on the obtained dynamic temperature data corresponding to different optical fiber channels and the dynamic stress data corresponding to different optical fiber channels, so as to filter out the first type of stress change characteristics caused by temperature changes in the measured stress data, thereby using the corrected dynamic stress data to analyze the sealing failure mechanism of the current gas channeling phenomenon in the same manner as above (including the diagnosis of the cause of sealing failure, or including the diagnosis of the cause of sealing failure and the diagnosis of the specific type of strength damage).

[0069] Specifically, when correcting the dynamic stress data, the sealing analysis device 40 will first calculate the stress change caused by the temperature change corresponding to the unit temperature collection time interval at each temperature collection moment for each channel related to the temperature measurement, so as to obtain the temperature-based dynamic stress change for each wellbore component (the temperature-based dynamic stress change includes: the stress change corresponding to each temperature collection moment), and then (because the pressure collection time interval is the same as the temperature collection time interval) the real-time pressure data at each pressure collection moment corresponding to each stress measurement channel is subtracted from the stress change at each temperature collection moment corresponding to the same component, according to the collection moment, so as to obtain a set of new dynamic stress data (i.e., corrected dynamic stress data) for each stress measurement channel, which filters out the stress change characteristics caused by temperature changes in the measured stress data. In this way, the sealing analysis device 40 uses the corrected dynamic stress data obtained from different stress measurement channels to diagnose the cause of sealing failure and the specific type of strength damage under strength damage.

[0070] The embodiment of the present invention arranges grating pressure sensors in two directions of the casing and the outer tube and in three directions of the cement ring, so that stress and strain in multiple directions can be detected, and multiple sensors are arranged in each direction. At the same time, multiple groups of grating temperature sensors are arranged at different wellbore positions. By comparing all pressure measurement results and / or temperature measurement results, the influence of temperature change on the strain factor is considered together. By eliminating the influence of temperature, the strain and stress measurement results can be made more accurate, thereby obtaining a more accurate sealing failure mechanism corresponding to different complex wellbore working environments, which is more conducive to establishing a quantitative judgment criterion for the wellbore sealing integrity failure mechanism.

[0071] Example 1

[0072] Circumferential and axial grating sensors are arranged on the outer wall of the simulated wellbore outer tube and casing, and circumferential, radial and circumferential sensors are arranged on the annular fiber optic bracket. Each sensor is connected to the regulator. Cement slurry is prepared according to the formula of 100% oil well cement + 40% water + 4% fluid loss agent, injected into the wellbore annulus, and the upper and lower sealing covers are pressed tightly. Heat to 80℃ for curing for 72h. 1MPa gas is injected into the bottom annulus section to detect the sealing of the wellbore and maintain gas stability. The pressure system is used to apply a maximum cyclic pressure of 70MPa to the casing, and the strain conditions in all directions of the wellbore are tested at the same time. After 3 cycles, the sealing detection system found that gas channeling occurred. At the same time, the maximum radial stress of the cement ring is tested in real time, which is -13.5MPa, the circumferential stress is 0.46MPa, and the axial stress is -0.37MPa; the circumferential stress of the casing is 9.7MPa, and the axial stress is -8.1MPa; the circumferential stress of the outer tube is 5.4MPa, and the axial stress is -3.9MPa. The stresses of cement ring, casing and outer tube did not reach their strength limits, and no strength damage occurred in various parts of the wellbore. However, the cement ring suffered interface bonding damage and sealing failure.

[0073] Example 2

[0074] Circumferential and axial grating sensors are arranged on the outer wall of the simulated wellbore and the outer wall of the casing, and circumferential, radial and circumferential sensors are arranged on the annular fiber optic bracket, and each sensor is connected to the regulator. Cement slurry is prepared according to the formula of 100% oil well cement + 40% water + 4% fluid loss agent, injected into the wellbore annulus, and the upper and lower sealing covers are pressed tightly. Heat to 80℃ and maintain for 72h. 1MPa gas is injected into the bottom annulus section to detect the sealing of the wellbore and maintain gas stability. The pressure inside the casing is raised to 110MPa using a pressurization system. The sealing detection system found that gas channeling occurred, and at the same time measured the maximum radial stress of the cement ring -19.2MPa, the circumferential stress was 1.58MPa, and the axial stress was -0.52MPa; the circumferential stress of the casing was 14.4MPa, and the axial stress was -12.5MPa; the circumferential stress of the outer cylinder was 8.7MPa, and the axial stress was -5.4MPa. The stress of the casing and the outer tube did not reach their strength limit. The maximum circumferential stress of the cement ring exceeded the tensile strength of the cement stone. The tensile strength of the cement ring was destroyed, resulting in the failure of the sealing integrity of the cement ring.

[0075] Example 3

[0076] Circumferential and axial grating sensors are arranged on the outer wall of the simulated wellbore and the outer wall of the casing, and circumferential, radial and circumferential sensors are arranged on the annular fiber optic bracket. Each sensor is connected to the regulator. Cement slurry is prepared according to the formula of 100% oil well cement + 40% water + 4% fluid loss reducer, injected into the wellbore annulus, and the upper and lower sealing covers are pressed tightly. Heat to 80℃ and maintain for 72h. 1MPa gas is injected into the bottom annulus section to detect the sealing of the wellbore and maintain gas stability. Use the temperature system to heat the wellbore system to 120℃, maintain for 30min, then reduce to room temperature 25℃, maintain for 30min, and repeat the heating and cooling cycle. After five cycles, the sealing detection system found that gas channeling occurred. At the same time, the maximum radial stress of the cement ring due to the temperature difference was -11.8MPa, the circumferential stress was 0.72MPa, and the axial stress was -0.36MPa; the circumferential stress of the casing was 10.7MPa, and the axial stress was -8.3MPa; the circumferential stress of the outer tube was 6.2MPa, and the axial stress was -3.9MPa. The stress of the cement ring, casing, and outer tube did not reach its strength limit, and the wellbore did not suffer from strength damage; the cement ring suffered from interface bonding damage, resulting in failure of the wellbore sealing integrity.

[0077] On the other hand, based on the above-mentioned wellbore sealing integrity testing system, an embodiment of the present invention further provides a method for testing the wellbore sealing integrity, which is implemented by the above-mentioned wellbore sealing integrity testing system. Figure 4 1 is a step diagram of a method for testing wellbore sealing integrity according to an embodiment of the present application.

[0078] like Figure 4As shown, the first example of the wellbore sealing integrity test method described in the embodiment of the present invention includes the following steps: step S401 deploys a strain acquisition device; step S402 seals the wellbore annulus, and then implements a gas channeling phenomenon test for simulating complex working conditions of the wellbore; step S403 synchronously acquires optical fiber feedback signals representing stress change characteristics of various components of the wellbore in different directions during the gas channeling phenomenon test; step S404 receives the optical fiber feedback signals acquired in step S403 through an optical fiber cable and demodulates them, and then determines the dynamic stress data corresponding to each component in different directions; step S405 analyzes the sealing failure mechanism that produces the current gas channeling phenomenon based on the dynamic stress data obtained in step S404.

[0079] Furthermore, the wellbore sealing integrity testing method described in the embodiment of the present invention also includes: when implementing the gas channeling phenomenon test based on temperature change, receiving and demodulating the optical fiber feedback signals transmitted by each sensor group representing different position and direction combination conditions, and obtaining the corresponding dynamic stress data under the different position and direction combination conditions of the wellbore; judging whether the stress of each combination condition reaches the ultimate strength of the corresponding position characteristic according to the dynamic stress data corresponding to different optical fiber channels, so as to determine the cause of the current wellbore sealing failure, so as to associate the gas channeling data corresponding to the current test, the dynamic stress data of different optical fiber channels, and the cause of sealing failure to form the data, wherein the cause of sealing failure is interface junction damage or strength damage.

[0080] Furthermore, a second example of the wellbore sealing integrity test method described in an embodiment of the present invention includes the following steps: deploying a strain acquisition device and a temperature acquisition device; sealing the wellbore annulus, and then implementing a gas channeling phenomenon test for simulating complex working conditions of the wellbore; in the process of implementing the gas channeling phenomenon test, synchronously acquiring optical fiber feedback signals characterizing stress change characteristics of each component of the wellbore in different directions, and synchronously acquiring optical fiber feedback signals characterizing temperature change characteristics of each component of the wellbore; receiving the optical fiber feedback signal acquired in the previous step through an optical fiber cable and demodulating it, and then determining the dynamic stress data corresponding to each component in different directions, and the dynamic stress data corresponding to each component; correcting the dynamic stress data according to the dynamic stress data and dynamic stress data obtained in the previous step, so as to use the corrected dynamic stress data to analyze the sealing failure mechanism that produces the current gas channeling phenomenon.

[0081] The present invention discloses a system and method for testing the sealing integrity of a wellbore. The system and method use fiber grating sensor technology to arrange a multi-channel pressure sensor group and a multi-channel temperature sensor group at different parts and stress directions of the wellbore. In the process of testing the gas channeling phenomenon that simulates the complex working conditions of the wellbore, it can continuously and accurately measure the parameters such as multi-directional and multi-point strain and temperature change of the wellbore in real time, monitor and evaluate the sealing integrity of the wellbore under various complex conditions, and form a system to analyze the mechanical and temperature deformation laws to evaluate whether the various components of the wellbore are damaged, and reveal the failure mechanism of the sealing integrity of the wellbore, and further establish its quantitative judgment criteria, so as to provide a scientific basis and guidance for improving the sealing of oil and gas wellbores. In addition, the present invention also has the advantages of small size, high sensitivity, high temperature resistance, multi-directional testing, and one-line multi-point arrangement.

[0082] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any person familiar with the technology within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

[0083] It should be understood that the embodiments disclosed in the present invention are not limited to the specific structures, processing steps or materials disclosed herein, but should be extended to equivalent substitutions of these features understood by ordinary technicians in the relevant field. It should also be understood that the terms used herein are only used for the purpose of describing specific embodiments and are not meant to be limiting.

[0084] The "one embodiment" or "embodiment" mentioned in the specification means that the specific features, structures or characteristics described in conjunction with the embodiment are included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment" or "embodiment" appearing in various places throughout the specification do not necessarily refer to the same embodiment.

[0085] Although the embodiments disclosed in the present invention are as above, the contents described are only embodiments adopted for facilitating the understanding of the present invention and are not intended to limit the present invention. Any technician in the technical field to which the present invention belongs can make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in the present invention, but the patent protection scope of the present invention shall still be subject to the scope defined in the attached claims.

Claims

1. A system for testing the integrity of a wellbore seal, comprising: A sealing test device, which is used to perform a gas channeling test for simulating complex working conditions in the wellbore after the wellbore annulus is sealed; The strain acquisition device is used to synchronously acquire optical fiber feedback signals representing stress change characteristics of various components of a wellbore in different directions during a gas channeling phenomenon test, wherein the optical fiber feedback signals representing circumferential stress change characteristics of the middle part of the casing obtained by each optical fiber Bragg grating pressure sensor on the first optical fiber cable, the optical fiber feedback signals representing circumferential stress change characteristics of the casing end obtained by each optical fiber Bragg grating pressure sensor on the second optical fiber cable, the optical fiber feedback signals representing axial stress change characteristics of the casing obtained by each optical fiber Bragg grating pressure sensor on the third optical fiber cable, and the optical fiber feedback signals representing circumferential stress change characteristics of the outer tube middle part obtained by each optical fiber Bragg grating pressure sensor on the fourth optical fiber cable are synchronously acquired. the optical fiber feedback signal representing the change characteristics of the circumferential stress at the end of the outer cylinder obtained by each fiber grating pressure sensor on the fifth optical fiber cable, the optical fiber feedback signal representing the change characteristics of the axial stress of the outer cylinder obtained by each fiber grating pressure sensor on the sixth optical fiber cable, the optical fiber feedback signal representing the change characteristics of the circumferential stress of the cement ring obtained by each fiber grating pressure sensor on the seventh optical fiber cable, the optical fiber feedback signal representing the change characteristics of the radial stress of the cement ring obtained by each fiber grating pressure sensor on the eighth optical fiber cable, and the optical fiber feedback signal representing the change characteristics of the axial stress of the cement ring obtained by each fiber grating pressure sensor on the ninth optical fiber cable; A temperature acquisition device, which is used to synchronously acquire, during the gas channeling test, the optical fiber feedback signal representing the dynamic change characteristics of the casing temperature obtained by each fiber Bragg grating temperature sensor on the tenth optical fiber cable, the optical fiber feedback signal representing the dynamic change characteristics of the outer tube temperature obtained by each fiber Bragg grating temperature sensor on the eleventh optical fiber cable, and the optical fiber feedback signal representing the dynamic change characteristics of the cement ring temperature obtained by each fiber Bragg grating temperature sensor on the twelfth optical fiber cable; A demodulation processing device, which is connected to the strain acquisition device and the temperature acquisition device through an optical fiber cable, and is used to receive the optical fiber feedback signal and perform demodulation, and then determine the dynamic temperature data corresponding to different optical fiber channels and the dynamic stress data corresponding to different sensor position and direction combination conditions, based on which, the dynamic stress data corresponding to different optical fiber channels are corrected; The sealing analysis device is used to analyze the sealing failure mechanism that produces the current gas channeling phenomenon based on the corrected dynamic stress data at different wellbore components and measurement directions, wherein it is judged whether the real-time stress at different sensor positions reaches the ultimate strength at the corresponding sensor installation position, thereby judging the cause of the current wellbore sealing failure, wherein the sealing failure cause is interface junction damage or strength damage, including: When the gas channeling phenomenon is detected, the real-time stress data in the dynamic stress data received by all channels related to the casing will be compared with the ultimate strength of the casing to determine whether the real-time stress of the casing has reached or exceeded its ultimate strength; the real-time stress data in the dynamic stress data received by all channels related to the outer tube will be compared with the ultimate strength of the outer tube to determine whether the real-time stress of the outer tube has reached or exceeded its ultimate strength; the real-time stress data in the dynamic stress data received by all channels related to the circumference or axial direction of the cement ring will be compared with the ultimate tensile strength of the cement ring to determine whether water leakage has occurred. The real-time stress of the mud ring reaches or exceeds its ultimate tensile strength; the real-time stress data in the dynamic stress data received by all channels related to the radial direction of the cement ring are compared with the ultimate compressive strength of the cement ring to determine whether the real-time stress of the cement ring reaches or exceeds its ultimate compressive strength. If none of the above four phenomena occur, the current cause of sealing failure is determined to be interface junction damage. If the seal detects any of the above phenomena, the current cause of sealing failure is determined to be strength damage and the specific type of strength damage is determined, wherein the identifiable specific strength damage type is selected from tensile damage, compressive damage and tensile damage.

2. The system according to claim 1, characterized in that The strain collection device comprises: A first casing circumferential sensor group, a second casing circumferential sensor group and a casing axial sensor group are arranged on the outer wall of the casing, wherein each sensor in the first casing circumferential sensor group is located in the middle of the casing and is spaced apart in the circumferential direction, each sensor in the second casing circumferential sensor group is located at the end of the casing and is spaced apart in the circumferential direction, and each sensor in the casing axial sensor group is spaced apart in the axial direction of the casing; An outer cylinder first circumferential sensor group, an outer cylinder second circumferential sensor group and an outer cylinder axial sensor group are arranged on the outer wall of the outer cylinder, wherein the sensors in the outer cylinder first circumferential sensor group are located in the middle of the outer cylinder and are spaced apart in the circumferential direction, the sensors in the outer cylinder second circumferential sensor group are located at the end of the outer cylinder and are spaced apart in the circumferential direction, and the sensors in the outer cylinder axial sensor group are spaced apart in the axial direction of the outer cylinder; and An annulus circumferential sensor group, an annulus radial sensor group and an annulus axial sensor group are arranged at the annulus support, wherein the annulus circumferential sensor group is located at the annulus support disk and is spaced apart along the circumferential direction of the disk, the annulus radial sensor group is located at the annulus support disk and is spaced apart along the specified radial direction of the disk, and the annulus axial sensor group is located at the annulus support leg and is spaced apart along the axial direction of the annulus.

3. The system according to claim 2, characterized in that Each sensor group calibrates the measuring points of each pressure sensor in the group through the optical fiber cable corresponding to the current sensor group.

4. The system according to any one of claims 1 to 3, characterized in that: The demodulation processing device is also used to receive the optical fiber feedback signals transmitted by each sensor group representing different position and direction combination conditions in the strain acquisition device respectively when implementing the gas channeling phenomenon test based on temperature change, and demodulate them to obtain the dynamic stress data corresponding to the different position and direction combination conditions of the wellbore; The sealing analysis device is also used to judge whether the stress of each combination condition reaches the ultimate strength of the corresponding position based on the dynamic stress data corresponding to different optical fiber channels, so as to determine the cause of the current wellbore sealing failure, so as to associate the gas channeling data corresponding to the current test, the dynamic stress data of different optical fiber channels, and the cause of the sealing failure to form data.

5. The system according to claim 4, characterized in that The sealing analysis device is also used to identify the stress direction of the stress collection position that reaches the ultimate strength when strength damage is detected, so as to clarify the specific type of strength damage, so as to associate the gas channeling data corresponding to the current test, the dynamic stress data of different optical fiber channels, the cause of sealing failure, and the specific type of strength damage to form the data.

6. The system according to claim 1, characterized in that The temperature acquisition device comprises: A casing temperature sensor group arranged in the middle of the casing; An outer cylinder temperature sensor group disposed in the middle of the outer cylinder; and An annular temperature sensor group is arranged at the annular support disc, wherein each sensor in the temperature acquisition device is a fiber grating temperature sensor, wherein each sensor group calibrates the measuring point of each temperature sensor in the group through the optical fiber cable corresponding to the current sensor group.

7. The system according to claim 6, characterized in that The demodulation processing device is further used to receive and demodulate the optical fiber feedback signals transmitted from the sensor groups representing different parts of the temperature acquisition device, respectively, when implementing the gas channeling phenomenon test including pressure change, to obtain the dynamic temperature data corresponding to different positions of the wellbore, and to receive and demodulate the optical fiber feedback signals transmitted from the sensor groups representing different position and direction combination conditions, respectively, to obtain the dynamic stress data corresponding to different position and direction combination conditions of the wellbore; The sealing analysis device is further used to correct the dynamic stress data corresponding to the different optical fiber channels according to the dynamic temperature data corresponding to the different optical fiber channels and the dynamic stress data corresponding to the different optical fiber channels, so as to filter out the first type of stress change characteristics caused by temperature changes in the measured stress data, thereby using the corrected dynamic stress data to analyze the sealing failure mechanism of the current gas channeling phenomenon.

8. A method for testing the integrity of a wellbore seal, characterized in that: The method is implemented by using the system according to any one of claims 1 to 7, and the method comprises: deploying strain collection devices; The wellbore annulus is sealed and then a gas channeling test is conducted to simulate the complex working conditions of the wellbore; During the gas channeling test, the optical fiber feedback signal representing the stress variation characteristics of each component of the wellbore in different directions is collected synchronously; The optical fiber feedback signal is received and demodulated through an optical fiber cable, and then the dynamic stress data corresponding to each component part in different directions is determined; Based on the dynamic stress data, the seal failure mechanism that produces the current gas channeling phenomenon is analyzed.

9. The method according to claim 8, characterized in that The method further comprises: When implementing the gas channeling phenomenon test based on temperature change, the optical fiber feedback signals transmitted by the sensor groups representing different position and direction combination conditions are respectively received and demodulated to obtain the dynamic stress data corresponding to the different position and direction combination conditions of the wellbore; According to the dynamic stress data corresponding to different optical fiber channels, it is judged whether the stress of each combination condition reaches the ultimate strength of the corresponding position characteristics, so as to determine the cause of the current wellbore seal failure, and to associate the gas channeling data corresponding to the current test, the dynamic stress data of different optical fiber channels, and the cause of the seal failure to form data.

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