Measuring system and measuring method of fluorescence type optical fiber high-temperature pressure gauge

Abstract

The invention discloses a measuring system and a measuring method of a fluorescence type optical fiber high-temperature pressure gauge. The measuring system comprises an optical fiber high-temperature pressure gauge, a demodulation host and a transmission optical cable, wherein the optical fiber high-temperature pressure gauge is used for collecting underground pressure and temperature; the demodulation host is used for outputting pulse pump light to the optical fiber high-temperature pressure gauge and receiving feedback signals; the demodulation host divides the signal into two identical paths, one path is transmitted to an underground optical fiber high-temperature pressure gauge, the other path is transmitted to the interference demodulation module and the temperature demodulation module, and a pressure value is obtained by simulating the change of the arm length difference between the interference optical cavity and the interference optical cavity of the optical fiber high-temperature pressure gauge; and a temperature value is obtained by comparing the fluorescence lifetime curve of the temperature demodulation module with the received fluorescence lifetime curve of the optical fiber high-temperature pressure gauge. According to the invention, temperature measurement and pressure measurement are simultaneously carried out in an underground high-temperature environment by using a fluorescence effect, and the stress surface of the optical fiber high-temperature pressure gauge under high pressure is directly used as a reflecting surface, so that the risk that an optical fiber grating is easy to fall off or break in the prior art is overcome.

Description

Technical Field

[0001] The invention belongs to the technical field of optical fiber sensors, and in particular relates to a measurement system and a measurement method based on an optical fiber high-temperature pressure gauge. Background Art

[0002] In the process of oil and coalbed methane exploration and development, such as drilling, completion and drainage, it is necessary to detect downhole pressure, especially in the drainage process. In today's oil well pressure detection market, electric high-temperature pressure gauges are generally used to measure downhole pressure. However, traditional electric high-temperature pressure gauges are prone to static electricity in the measurement system, and even produce ionization effects under the action of strong electric fields, causing discharge and forming electric sparks, which poses a safety hazard. In addition, traditional electric high-temperature pressure gauges are easily affected by factors such as environmental noise and electromagnetic interference during the signal amplification process, and the measured data results will have insufficient measurement accuracy and unstable data transmission.

[0003] Fiber optic high temperature pressure gauges are different from traditional electrical high temperature pressure gauges and can work in high temperature and high pressure environments for a long time. Fiber optic high temperature pressure gauges generally use the principle of light modulation. When external pressure acts on the optical fiber, the phase, intensity, frequency, etc. of the modulated light transmitted in the optical fiber change. Using the basic interference principle and optical signal detection and conversion system, the relationship between the changes in phase, intensity, frequency, etc. and the external pressure can be measured. Since the optical fiber itself is resistant to high temperatures, it is feasible to make a high temperature pressure gauge.

[0004] Many fiber optic high temperature pressure gauges currently use fiber grating structures. The fiber grating structure of the high temperature pressure gauge is simple in structure and easy to prepare successfully; the demodulation signal is simple. However, it still has its disadvantages: 1) The demodulation equipment cost is relatively high; 2) In the high temperature and high pressure detection environment, the fiber grating is subjected to tension for a long time, and the fiber is prone to aging and fatigue. After a long working time, the fiber is easy to break. In the entire downhole fiber optic high temperature pressure measurement system, the fiber optic high temperature pressure gauge has become a key research, so a low-cost and efficient solution is urgently needed for measurement in such a harsh environment of high temperature and high pressure. Summary of the invention

[0005] A brief summary of embodiments of the present invention is provided below to provide a basic understanding of certain aspects of the present invention. It should be understood that the following summary is not an exhaustive summary of the present invention. It is not intended to identify key or important parts of the present invention, nor is it intended to limit the scope of the present invention. Its purpose is merely to provide certain concepts in a simplified form as a prelude to a more detailed description discussed later.

[0006] In order to solve the technical problems raised in the background technology section, the purpose of the present invention is to provide a fluorescent fiber optic high-temperature pressure gauge that can measure both high temperature and high pressure, a measuring system and a testing method including the fluorescent high-temperature pressure gauge, so as to solve the above technical problems.

[0007] According to one aspect of the present application, a measurement system of a fluorescence-type optical fiber high-temperature pressure gauge is provided, comprising an optical fiber high-temperature pressure gauge for collecting downhole pressure and temperature, a demodulation host for outputting pulse pump light to the optical fiber high-temperature pressure gauge and receiving a feedback signal, and a transmission optical cable for connecting the optical fiber high-temperature pressure gauge and the demodulation host; wherein the optical fiber high-temperature pressure gauge comprises a temperature measurement part and a pressure measurement part, the demodulation host comprises a pump laser generating device for outputting pulse pump light to the optical fiber high-temperature pressure gauge, an interference demodulation module for simulating an interference optical cavity, and a temperature demodulation module for obtaining a fluorescence lifetime curve, the simulated interference optical cavity of the interference demodulation module is connected to the optical fiber high-temperature pressure gauge, and the temperature demodulation module is connected to the optical fiber high-temperature pressure gauge. The interference optical cavity of the pressure measuring part of the meter has the same configuration (it can have the same parameters or parameters configured in proportion), and the temperature demodulation module has the same gain medium as the temperature measuring part of the optical fiber high-temperature pressure gauge; the pump laser generating device of the demodulation host divides the signal into two identical paths, one of which is transmitted to the optical fiber high-temperature pressure gauge downhole, and the other is transmitted to the interference demodulation module and the temperature demodulation module, and the demodulation of the downhole pressure value is realized by simulating the change of the arm length difference between the interference optical cavity and the interference optical cavity of the optical fiber high-temperature pressure gauge, and the downhole temperature value is obtained by comparing the fluorescence lifetime curve of the temperature demodulation module with the fluorescence lifetime curve of the received optical fiber high-temperature pressure gauge.

[0008] As a further solution, the fiber optic high temperature pressure gauge includes a fiber optic collimator and a pump optical gain medium for temperature measurement, and an optical interference high-voltage detection module for pressure measurement, one end of the fiber optic collimator is connected to the pump optical gain medium and the optical interference high-voltage detection module in sequence, and the other end of the fiber optic collimator is connected to the transmission optical cable and the demodulation host in sequence; the optical interference arm length difference of the optical interference high-voltage detection module is linearly related to the external pressure, when the external pressure acts on the optical interference high-voltage detection module, the optical interference arm length difference changes, and the analog interference optical cavity of the demodulation host is used for comparison, so as to demodulate the external pressure value; the pump optical gain medium generates a spontaneous radiation fluorescence effect after the pulse pump light is input through the transmission optical cable, and the temperature demodulation module of the demodulation host calculates the temperature value by comparing the received fluorescence lifetime curve with the preset fluorescence lifetime curve; the input light source of the optical interference high-voltage detection module is a fluorescent broadband light source generated after the pulse pump light passes through the pump optical gain medium.

[0009] The optical fiber high temperature pressure gauge is a fluorescent optical fiber high temperature pressure gauge that can measure both high temperature and high pressure. The current optical fiber high temperature pressure gauge can only collect downhole pressure. If the temperature needs to be measured, another temperature measurement system is required. This application can achieve synchronous temperature collection through a special optical fiber high temperature pressure gauge and a demodulation host that cooperates with it, greatly reducing the cost of the temperature and pressure measurement demodulation system.

[0010] Among them, the optical interference high-pressure detection module for pressure measurement is located on the end face or side of the optical fiber high-temperature pressure gauge. When the end face or side of the optical fiber high-temperature pressure gauge is affected by external pressure, the signal arm length of the optical interference detection part changes. The optical interference of the optical interference high-pressure detection module can be Fabry-Perot interference, Michelson interference, or Mach-Zehnder interference. The arm length difference of the optical interference is relatively small by design, that is, the signal arm and the reference arm of the optical interference are almost equal. Because in the detection part of the designed high-temperature pressure gauge, the light source input by the optical interference high-pressure detection module is a fluorescent broadband light source generated after the pulse pump light passes through the gain medium. The fluorescence spectrum generated by spontaneous radiation here is a broadband laser. When the optical path difference of the optical interference high-pressure detection module is equal to the optical path difference of the analog interference cavity in the optical wavelength demodulation module in the demodulation host, the light intensity value will greatly increase, and the interference arm length difference of the optical interference high-pressure detection module is linearly related to the external pressure. When the external pressure acts on the optical interference high-pressure detection module, the arm length difference of the optical interference changes, and the analog interference optical cavity in the interference demodulation module is compared, so that the external pressure value can be demodulated.

[0011] The main function of the above-mentioned transmission optical cable, optical fiber collimator, and pump optical gain medium is to measure the temperature of the environment, and also to output a fluorescent broadband light source to the optical interference high-voltage detection module. The main principle of measuring temperature is that when the pulsed pump light is input through the optical fiber transmission part, the pump optical gain medium will produce a spontaneous radiation fluorescence effect, and the fluorescence lifetime is related to the temperature of the environment. When the ambient temperature is relatively high, the fluorescence lifetime will be very short, and when the ambient temperature is relatively low, the fluorescence lifetime will be relatively long. In the temperature demodulation module, there is also the same gain medium material, which also produces fluorescence. By comparing the fluorescence lifetime curve in the demodulation module with the fluorescence lifetime curve of the downhole optical fiber high-temperature pressure gauge, the downhole temperature can be finally calculated.

[0012] As a specific example, the optical fiber high temperature pressure gauge comprises a housing, a high temperature optical fiber, a high temperature optical fiber collimator, an optical fiber collimator seal, a first optical gain medium and a Fabry-Perot interferometer cavity, wherein the housing seals the high temperature optical fiber collimator, the first optical gain medium and the Fabry-Perot interferometer cavity through the optical fiber collimator seal, and the end face of the optical fiber high temperature pressure gauge is a stress face of the Fabry-Perot interferometer cavity for stress detection. The housing is preferably a metal shell.

[0013] As a specific example, the demodulation host includes a broadband filter, a first coupler, a second coupler, a third coupler, a pulse pump generator, a fluorescence time domain signal acquisition module and a fluorescence wavelength demodulation module. The fluorescence time domain signal acquisition module includes a second fiber collimator, a second optical gain medium, a first photoelectric conversion module, a second photoelectric conversion module, and a signal acquisition processing module; the fluorescence wavelength demodulation module includes a third fiber collimator, an analog light interference cavity, a PZT piezoelectric ceramic, a third photoelectric conversion module and a dual-channel signal acquisition module; the broadband filter, the first coupler and the pulse pump generator are connected in sequence, the first coupler and the second coupler are connected to each other, the second optical gain medium, the second fiber collimator, the second coupler and the first photoelectric conversion module are connected in sequence, the broadband filter, the third coupler and the second photoelectric conversion module are connected in sequence, the first photoelectric conversion module and the second photoelectric conversion module are both connected to the signal acquisition processing module, and the third coupler is also respectively connected to the third fiber collimator and The third photoelectric conversion module is connected, the third fiber collimator is connected to the simulated light interference cavity and the PZT piezoelectric ceramic, and the third photoelectric conversion module is connected to the dual-channel signal acquisition module; the pump light of the pulse pump generator is split through the first coupler to the fiber high-temperature pressure gauge in one way, and split through the first coupler and the second coupler to the second fiber collimator and the second optical gain medium to generate fluorescence, and the generated fluorescence is converted into an electrical signal by the first photoelectric conversion module, and the two fluorescences are simulated and calculated to finally obtain the lifetime of the returned fluorescence of the fiber high-temperature pressure gauge; the pump light of the pulse pump generator is split through the first coupler to the Fabry-Perot interference cavity of the fiber high-temperature pressure gauge to form broadband light of fluorescence interference fringes, and the broadband light is transmitted through the optical fiber return transmission cable, and enters the fluorescence wavelength demodulation module through the broadband filter; the returned interference light passes through the third fiber collimator and the simulated light interference cavity, and then the length of the interference cavity after the Fabry-Perot interference cavity is subjected to pressure is measured through the cavity length of the PZT piezoelectric ceramic, thereby obtaining the external pressure.

[0014] The second optical gain medium has the same size and material as the first optical gain medium.

[0015] According to another aspect of the present application, a measurement method of a fluorescence optical fiber high temperature pressure gauge is provided, comprising:

[0016] Installation steps: first fix the fluorescent fiber optic high temperature pressure gauge to the downhole end of the transmission optical cable; then connect the other end of the transmission optical cable to the demodulation host of the fluorescent fiber optic high temperature pressure gauge. The specific process is as follows: fix the fiber optic high temperature pressure gauge to the bottom of the transmission optical cable (or logging optical cable) of the well logging. After installation, the stress surface of the fiber optic high temperature pressure gauge is in contact with the outside world, or an oil bag is used for oil sealing; the optical fiber at the input end of the fiber optic high temperature pressure gauge is connected to the transmission optical cable; at the same time, the connection between the fiber optic high temperature pressure gauge and the transmission optical cable end downhole and the outer shell of the fiber optic high temperature pressure gauge are sealed in a metal tube; the transmission optical cable at the wellhead is connected to the demodulation host;

[0017] Pressure measurement steps: The demodulation host outputs pulse pump light which is input into the optical fiber through the transmission optical cable and finally input into the pump optical gain medium, thereby generating fluorescence; after the fluorescence is output to the optical interference high-voltage detection module, it is returned to the demodulation host at the wellhead through the transmission optical cable; the downhole pressure value is obtained by simulating the change in the arm length difference between the interference optical cavity and the interference optical cavity of the optical fiber high-temperature pressure gauge;

[0018] Temperature measurement steps: The demodulation host divides the optical signal into two parts, one part measures the fluorescence lifetime of the returned optical signal, and the other part measures the interference fringes of the returned optical signal; when the optical fiber high-temperature pressure gauge is affected by the ambient temperature, the returned fluorescence lifetime will change. The higher the temperature, the shorter the fluorescence lifetime will be, and the lower the temperature, the longer the fluorescence lifetime will be; when the pulse output pump light is input to the gain medium, the optical power of the pulse pump light is sufficient for the fluorescence saturation output of the gain medium; when the gain medium has no pump light, the fluorescence will continue to output and then decay rapidly, and the decay time is related to the ambient temperature; by using the pulse signal as the trigger signal, the fluorescence lifetime of the gain medium in the demodulation host and the gain medium of the optical fiber high-temperature pressure gauge is accumulated multiple times and measured at the same time, and the temperature value of the optical fiber high-temperature pressure gauge can be obtained by comparative calculation.

[0019] The fluorescence spectrum generated by spontaneous radiation here is a broadband laser. When the optical path difference of the optical interference high-voltage detection module is equal to the optical path difference of the simulated interference cavity in the optical wavelength demodulation module in the demodulation host, the light intensity value will increase greatly, and the interference arm length difference of the optical interference high-voltage detection module is linearly related to the external pressure.

[0020] During measurement, the pulse pump laser generator in the demodulation host is output through the fiber coupler, and the returned signal is also input into the fluorescence time domain signal acquisition module through the fiber coupler, and the fluorescence wavelength demodulation module performs data processing. The fluorescence time domain signal acquisition module finally outputs the ambient temperature of the fiber optic high temperature pressure gauge; the fluorescence wavelength demodulation module outputs the pressure information of the environment of the fiber optic high temperature pressure gauge.

[0021] The present invention adopts the above technical solution, and measures the returned fluorescence lifetime by demodulating the fluorescence time domain module in the host, and after data processing, the temperature information of the downhole detection point can be obtained; and detects the returned fluorescence interference spectrum by demodulating the fluorescence wavelength demodulation module in the host, and after data processing, the pressure information of the downhole detection point can be obtained. Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) Use the fluorescence effect to measure the temperature of the underground high-temperature environment. The demodulation host outputs pump light to the underground gain medium, and the fluorescence generated by the gain medium returns to the demodulation host to measure the lifetime of the fluorescence.

[0023] (2) Use fluorescence effect to measure downhole pressure. Fluorescence is used as a broadband light source to input into the optical interference high-pressure detection module. The returned interference light signal reflects the interference arm length difference of the optical interference detection part through the interference fringes on the spectrum, and this interference arm length difference is related to the external pressure.

[0024] (3) By using single-mode optical fiber for optical transmission, real-time temperature and pressure monitoring can be performed at remote locations. At the same time, when measuring temperature and pressure remotely, there is no need to provide power to the fluorescent optical fiber high-temperature pressure gauge.

[0025] (4) The stress surface under high pressure is directly used as a reflection surface. Unlike fiber Bragg grating, the fiber of the fiber Bragg grating is in contact with the stress surface, which poses a certain risk, that is, the fiber Bragg grating will fall off the stress surface, or the fiber Bragg grating will break under long-term tension. However, in the optical interference high-pressure detection module of the fluorescent fiber optic high-temperature pressure gauge, the light is directly reflected back from the stress surface, so there is no risk like the fiber Bragg grating.

[0026] (5) By adjusting the interference arm length difference of the optical interference cavity in the demodulation module, the range of the interference arm length difference is within the range of the arm length difference variation of the optical interference high-pressure detection module of the optical fiber high-temperature pressure gauge, so that the light output intensity value returned by the fluorescence is within the measurable range.

[0027] (6) The temperature change information measured by the fluorescence fiber optic high temperature pressure gauge is reflected by the change of fluorescence lifetime, and the pressure change information is reflected by the change of fluorescence light interference signal. The fluorescence lifetime change and fluorescence interference spectrum can be accumulated through multiple pulses to increase the signal-to-noise ratio. The laser carrying temperature and pressure information can be transmitted back to the remote signal processing equipment over a long distance through the transmission fiber for data analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention may be better understood by referring to the following description given in conjunction with the accompanying drawings, wherein the same or similar reference numerals are used throughout the drawings to represent the same or similar components. The accompanying drawings, together with the following detailed description, are included in and form a part of this specification and are used to further illustrate the preferred embodiments of the present invention and to explain the principles and advantages of the present invention. In the drawings:

[0029] Figure 1 It is a schematic diagram of the principle of the measurement system based on the optical fiber high temperature pressure gauge of the present invention;

[0030] Figure 2 Schematic diagram of the overall structure of a measurement system based on an optical fiber high temperature pressure gauge in an embodiment of the present invention;

[0031] Figure 3 It is a schematic diagram of how the PZT piezoelectric ceramic changes the optical cavity length through a triangular wave signal of spectral demodulation in an embodiment of the present invention;

[0032] Figure 4 Schematic diagram of the fluorescence characteristic curve in an embodiment of the present invention;

[0033] In the figure: 1. high-temperature optical fiber; 2. optical fiber collimator seal; 3. shell (shell of optical fiber high-temperature pressure gauge); 4. high-temperature optical fiber collimator; 5. first optical gain medium; 6. Fabry-Perot interferometer cavity (for stress detection); 100. optical fiber high-temperature pressure gauge; 8. transmission optical cable (well logging high-temperature optical cable); 9. broadband filter; 10. first coupler; 101. second coupler; 102. third coupler; 11. pulse pump generator; 12. second optical fiber collimator; 13. optical gain medium (same size and material as 5); 14. first photoelectric conversion module; 15. second photoelectric conversion module; 16. signal acquisition and processing module; 210. fluorescence time-domain signal acquisition module; 18. third optical fiber collimator; 19. analog optical interference cavity; 20. PZT piezoelectric ceramics; 21. third photoelectric conversion module; 22. dual-channel signal acquisition module; 220. fluorescence wavelength demodulation module; 200. demodulation host. DETAILED DESCRIPTION

[0034] Embodiments of the present invention will be described below with reference to the accompanying drawings. Elements and features described in one drawing or one embodiment of the present invention may be combined with elements and features shown in one or more other drawings or embodiments. It should be noted that for the purpose of clarity, the representation and description of components and processes that are not related to the present invention and are known to those of ordinary skill in the art are omitted in the drawings and descriptions.

[0035] In the description of the present invention, it should be understood that the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. In addition, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, and it can be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] The present invention provides a measurement system and a measurement method of a fluorescent optical fiber high temperature pressure gauge, see Figure 1 The measuring system comprises an optical fiber high temperature pressure gauge, a demodulation host, and a transmission optical cable for connecting the optical fiber high temperature pressure gauge and the demodulation host; wherein the optical fiber high temperature pressure gauge comprises a temperature measuring part and a pressure measuring part, the demodulation host comprises a pump laser generating device for outputting pulse pump light to the optical fiber high temperature pressure gauge, an interference demodulation module for simulating an interference optical cavity, and a temperature demodulation module for obtaining a fluorescence lifetime curve, the simulated interference optical cavity of the interference demodulation module has the same configuration as the interference optical cavity of the pressure measuring part of the optical fiber high temperature pressure gauge, and the temperature demodulation module has the same gain medium as the temperature measuring part of the optical fiber high temperature pressure gauge; the pump laser generating device of the demodulation host divides the signal into two identical paths, one path is transmitted to the optical fiber high temperature pressure gauge downhole, and the other path is transmitted to the interference demodulation module and the temperature demodulation module, the demodulation of the downhole pressure value is realized by changing the arm length difference between the simulated interference optical cavity and the interference optical cavity of the optical fiber high temperature pressure gauge, and the downhole temperature value is obtained by comparing the fluorescence lifetime curve of the temperature demodulation module with the fluorescence lifetime curve of the received optical fiber high temperature pressure gauge.

[0037] Among them, the optical fiber high-temperature pressure gauge includes an optical fiber collimator and a pump optical gain medium for temperature measurement, and an optical interference high-voltage detection module for pressure measurement. One end of the optical fiber collimator is connected to the pump optical gain medium and the optical interference high-voltage detection module in sequence, and the other end of the optical fiber collimator is connected to the transmission optical cable and the demodulation host in sequence; the optical interference arm length difference of the optical interference high-voltage detection module is linearly related to the external pressure. When the external pressure acts on the optical interference high-voltage detection module, the optical interference arm length difference changes, and the analog interference optical cavity of the demodulation host is used for comparison to demodulate the external pressure value; the pump optical gain medium generates a spontaneous radiation fluorescence effect after the pulse pump light is input through the transmission optical cable, and the temperature demodulation module of the demodulation host calculates the temperature value by comparing the received fluorescence lifetime curve with the preset fluorescence lifetime curve; the input light source of the optical interference high-voltage detection module is a fluorescent broadband light source generated after the pulse pump light passes through the pump optical gain medium.

[0038] Example 1

[0039] As a specific implementation plan, Figure 2 As shown in the structure of the middle part, this embodiment provides a measurement system based on an optical fiber high-temperature pressure gauge, including 1. high-temperature optical fiber; 2. optical fiber collimator seal; 3. shell (shell of optical fiber high-temperature pressure gauge); 4. high-temperature optical fiber collimator; 5. first optical gain medium; 6. Fabry-Perot interferometer cavity (for stress detection); 8. transmission optical cable (well logging high-temperature optical cable); 9. broadband filter; 10. first coupler, 101, second coupler, 102, third coupler, 11, pulse pump generator; 12, second optical fiber collimator; 13, optical gain medium (same size and material as 5); 14, first photoelectric conversion module; 15, second photoelectric conversion module; 16, signal acquisition and processing module; 18, third optical fiber collimator; 19, simulated optical interference cavity; 20, PZT piezoelectric ceramics; 21, third photoelectric conversion module; 22, dual-channel signal acquisition module; 200, demodulation host.

[0040] The optical fiber high temperature pressure gauge 100 mainly includes a high temperature optical fiber 1, an optical fiber collimator seal 2, a housing 3, a high temperature optical fiber collimator 4, an optical gain medium 5 and a Fabry-Perot interferometer cavity 6. The housing 3 and the optical fiber collimator seal 2 seal the high temperature optical fiber collimator 4, the optical gain medium 5 and the Fabry-Perot interferometer cavity 6. The end face of the optical fiber high temperature pressure gauge 100 is the stress surface of the Fabry-Perot interferometer cavity 6.

[0041] The demodulation host 200 mainly includes a pump laser generator, a fluorescence time domain signal acquisition module 210 and a fluorescence wavelength demodulation module 220. The pump laser generator includes a broadband filter 9, a first coupler 10 and a pulse pump generator 11. The fluorescence time domain signal acquisition module 210 includes a second fiber collimator 12, a second optical gain medium 13 (same size and material as the first optical gain medium 5); two photoelectric conversion modules (a first photoelectric conversion module 14, a second photoelectric conversion module 15) and a signal acquisition processing module 16. The fluorescence wavelength demodulation module 220 mainly includes a third fiber collimator 18, a simulated optical interference cavity 19, a PZT piezoelectric ceramic 20, a third photoelectric conversion module 21 and a dual-channel signal acquisition module 22. The connection relationship is shown in the figure, the band filter, the first coupler and the pulse pump generator are connected in sequence, the first coupler and the second coupler are connected to each other, the second optical gain medium, the second fiber collimator, the second coupler and the first photoelectric conversion module are connected in sequence, the broadband filter, the third coupler and the second photoelectric conversion module are connected in sequence, the first photoelectric conversion module and the second photoelectric conversion module are both connected to the signal acquisition processing module, the third coupler is also connected to the third fiber collimator and the third photoelectric conversion module respectively, the third fiber collimator is connected to the simulated light interference cavity and the PZT piezoelectric ceramic, and the third photoelectric conversion module is connected to the dual-channel signal acquisition module. The interference demodulation module and the temperature demodulation module are implemented by the fluorescence time domain signal acquisition module 210 and the fluorescence wavelength demodulation module 220.

[0042] The pump laser generator outputs pulsed pump light to the high-temperature optical fiber. When the pulsed pump light is input to the pump gain medium, the gain medium will generate fluorescence, which is returned to the fluorescence time domain signal acquisition module. By measuring the fluorescence lifetime, the ambient temperature can be calculated. At the same time, fluorescence is a broadband laser. When the broadband laser is input to the high-voltage part of the optical interference detection, the returned fluorescence is input to the fluorescence wavelength demodulation module, which demodulates the arm length difference of the optical interference signal to obtain the change in external pressure.

[0043] The optical fiber high temperature pressure gauge 100 is connected to one end of the transmission optical cable 8 and placed underground; at the wellhead, the other end of the transmission optical cable 8 is connected to the output of the broadband filter 9 of the demodulation host 200.

[0044] The pulse pump light generator 11 of the demodulation host 200 emits a pulse pump laser, which passes through the wide-band first coupler 10 of the demodulation host 200, the broadband filter 9, the transmission optical cable 8, the high-temperature optical fiber 1 in the optical fiber high-temperature pressure gauge 100, the high-temperature optical fiber collimator 4 and the optical gain medium 5 in sequence.

[0045] After the pulsed pump laser passes through the optical gain medium 5, a fluorescence effect occurs.

[0046] After the pulsed pump laser passes through the optical gain medium 5, a part of the fluorescence directly returns to the broadband filter 9 through the transmission optical cable 8, and is then divided into the first photoelectric conversion module 5 of the fluorescence time domain signal acquisition module 210 through the broadband coupler to be converted into an electrical signal. At the same time, the pulsed pump light is also split by the second coupler 101 for collimation 12 and gain medium 13, and fluorescence is also generated. This part of the fluorescence is converted into an electrical signal through the first photoelectric conversion module 4 of the fluorescence time domain signal acquisition module 210. These two fluorescence time domain signals are simulated and calculated to finally obtain the lifetime of the returned fluorescence of the optical fiber high temperature pressure gauge 100, and then the temperature value of the surrounding environment of the optical fiber high temperature pressure gauge 100 can be calculated.

[0047] After the pulsed pump laser passes through the optical gain medium 5, another part of the fluorescence directly passes through the Fabry-Perot interference cavity 6. Broadband light with fluorescence interference fringes is formed in the Fabry-Perot interference cavity 6. This part of the light is then returned to the transmission optical cable 8, passes through the wide-band filter 9, and is then divided into the fluorescence wavelength demodulation module 220 through the third coupler 102. The returned interference light passes through the third fiber collimator 18 and the simulated light interference cavity 19. When the PZT piezoelectric ceramic 20 is driven, the PZT piezoelectric ceramic 20 causes the cavity length of the simulated light interference cavity 19 to change. When the cavity length is the same as the cavity length of the stress detection interference cavity, the light intensity value changes greatly, so that the length of the interference cavity of the Fabry-Perot interference cavity 6 after being subjected to pressure is measured through the cavity length of the PZT piezoelectric ceramic. This light interference cavity length value has a linear relationship with the external pressure.

[0048] The pressure at the downhole measurement point is set to P and the temperature is set to T. When there is no stress, the cavity length of the Fabry-Perot interferometer cavity used for stress detection is L.

[0049] The stress surface diaphragm of the Fabry-Perot interference cavity for stress detection has a radius of R1, a thickness of t, an elastic modulus of E1, a Poisson's ratio of u1, and a hard core radius of r1 at the center of the diaphragm.

[0050] When the pressure at the measuring point reaches a stable state, that is, when the pressure is P, the hard center displacement of the stress diaphragm is

[0051]

[0052] like Figure 3 As shown in the figure, the PZT piezoelectric ceramic changes the optical cavity length by demodulating the triangle wave signal of the spectrum demodulation module of the host. The relationship between the optical cavity length and time is:

[0053] s(t)=kt+l1

[0054] When the pressure measured by the optical fiber high temperature pressure gauge is 0 and the time is t1,

[0055] s(t1)=kt1+l1=L

[0056] When the length of the simulated light interference cavity is at t1, the length of the simulated light interference cavity is the same as that of the interference cavity of the optical fiber high temperature pressure gauge, and the measured light intensity value is an extreme value.

[0057] When the pressure measured by the optical fiber high temperature pressure gauge is P, when the time is t2

[0058] s(t2)=kt2+l1=L-ω

[0059] When the simulated light interference cavity length is at t2, the simulated light interference cavity length is the same as the interference cavity length of the fiber optic high temperature pressure gauge after being subjected to pressure, and the measured light intensity value is the extreme value. Then the variable of the cavity length is

[0060]

[0061] Within a certain temperature range, the fluorescence lifetime of optical gain media shows a certain temperature dependence under the action of pump light, and fluorescence lifetime temperature measurement is based on the temperature dependence of this temperature measurement principle.

[0062] When the pump light irradiates the optical gain medium, the electrons inside it gain energy and jump from the ground state to the excited state. The radiation energy released from the excited state back to the ground state causes the optical gain medium to emit fluorescence. After the pump light is gone, the duration of continuous fluorescence emission depends on the lifetime of the excited state, which is called the fluorescence lifetime. The length of the fluorescence lifetime is determined by the temperature. The fluorescence lifetime type temperature sensor is based on this characteristic.

[0063] Under the action of pump light, the optical gain medium will emit a certain linear spectrum, namely fluorescence and its afterglow. According to semiconductor theory, the decay and disappearance of afterglow is actually the quenching process of light. The increase in temperature increases the intensity of lattice vibration, and the increase in lattice vibration intensity increases the number of molecules involved in absorption, which ultimately shortens the fluorescence quenching process. Therefore, the temperature of the optical gain medium determines the speed of light quenching, that is, the size of the decay time constant. Figure 4 The fluorescence characteristic curve.

[0064] The functional relationship between the intensity of fluorescence afterglow and time is:

[0065]

[0066] In the formula, A-constant coefficient;

[0067] t-afterglow decay time;

[0068] l p (T)-peak fluorescence intensity when excitation is stopped, as a function of temperature T;

[0069] τ(T)-fluorescence afterglow decay time constant, that is, fluorescence afterglow lifetime, is also a function of temperature T and has nothing to do with light intensity.

[0070] After the pump light excites the gain medium in the fluorescence time domain module, under room temperature conditions, the fluorescence curve can be obtained as follows:

[0071]

[0072] After the pump light excites the gain medium of the fiber optic high-temperature pressure gauge in the fluorescence time domain module, the fluorescence curve can be obtained under high temperature conditions:

[0073]

[0074] When the amplification factor of the photoelectric conversion module is changed,

[0075] Bl p (T1)=Al p (T2)

[0076] Then we can calculate:

[0077]

[0078] Since the temperature of the demodulation host is known, τ(T1) is a known value. After dividing the fluorescence curve I1 under room temperature by the fluorescence curve I2 under high temperature,

[0079]

[0080] Generally, the higher the temperature of the surrounding environment, the smaller τ(T); by measuring the relationship between the fluorescence lifetime of the optical gain medium and the temperature value T, when we measure τ(T), we can obtain the temperature T value.

[0081] An embodiment of the present application is provided below with specific data: the full scale of the fluorescent fiber optic high-temperature pressure gauge is 100 MPa, the stress diaphragm of the Fabry-Perot interferometer cavity used for stress detection is a sapphire crystal, the thickness t of the sapphire crystal is 0.13 mm, the radius R is 1.5 mm, the hard core radius r of the center is 0 mm, the elastic modulus E of the sapphire crystal is 380 GPa, and the Poisson's ratio u is 0.23; the pump laser is 980 nm, and the optical gain medium is Er- and Yb-doped laser glass. Under the action of the pump laser, the laser glass generates a broadband fluorescent light source.

[0082] When the downhole pressure of the fluorescent fiber optic high temperature pressure gauge is 50MPa and the temperature is 150℃, the change of the cavity length of the Fabry-Perot cavity used for pressure detection of the fluorescent fiber optic high temperature pressure gauge is ω:

[0083]

[0084] Then the deformation of the center of the stress diaphragm reduces the length of the Fabry-Perot interferometer cavity used for stress detection. When there is no external pressure, the cavity length L is 500um.

[0085] When there is no external force acting on the optical fiber high temperature pressure gauge, the cavity length of the simulated optical interference cavity is driven by a triangular wave signal, the cavity length slope k of the PZT piezoelectric ceramic is 100 μm / s, and the cavity length intercept l1 is 250 μm.

[0086] s(t1)=kt1+l1=L

[0087] Then the time t1=2.5s when the light intensity reaches its extreme value can be measured.

[0088] When the cavity length is affected by stress, the cavity length becomes 446.2um. The time when the light intensity value reaches its extreme value is t2.

[0089] s(t2)=kt2+l1=L-ω

[0090] Then when t2=1.962s, the extreme light intensity value is measured.

[0091] When the maximum pressure value Pmax of the fluorescence fiber optic high temperature pressure gauge is 100MPa, the maximum change of the Fabry-Perot interferometer cavity length for stress detection is

[0092]

[0093] When the cavity length is affected by stress, the cavity length becomes 392.4um. The time when the light intensity value is measured is t3

[0094] s(t3)=kt3+l1=L-ω max

[0095] Then when t3=1.424s, the extreme light intensity value is measured.

[0096] From this we can see that after the PZT piezoelectric ceramic is driven by a triangular wave signal, the time t2 of the extreme value of the light intensity can be measured to obtain the pressure of the optical fiber high-temperature pressure gauge.

[0097]

[0098] The fluorescence fiber optic high temperature pressure gauge uses Er-doped and Yb-doped laser glass. When the temperature is -20℃ to 200℃, the fluorescence lifetime of Er-doped and Yb-doped laser glass increases from 11ms to 6.8ms, and changes linearly. The fluorescence time domain signal processing module of the demodulation host uses an accumulative data acquisition card. The pulse frequency of the pulse pump laser generator is 50Hz, the pulse width is 5ms, and the acquisition rate of the acquisition card is 2M / s, 12 bits.

[0099] Since the acquisition rate of the acquisition card is 2M / s. When the pulse signal of the pump laser is output to the acquisition card, the data acquisition card directly acquires the fluorescence signal. When the temperature is -20℃ to 200℃, the change in fluorescence lifetime is 4.2ms, and the temperature recognition accuracy is 4.2ms / 220℃=19us / ℃. The interval time of the data acquisition point of the acquisition card is 0.5us, so the recognition accuracy of the acquisition card is 0.026℃ / us. Therefore, the temperature measurement accuracy of the fluorescence fiber optic high temperature pressure gauge is 0.026℃ / us.

[0100] Example 2

[0101] This embodiment is based on the measurement system of Embodiment 1 and proposes a method for measuring downhole pressure and temperature based on the above-mentioned fluorescent optical fiber high-temperature pressure gauge, which includes an installation step and a measurement step.

[0102] The installation steps include: fixing the fiber optic high temperature pressure gauge at the bottom end of the logging transmission optical cable (or logging optical cable). After installation, the stress surface of the fiber optic high temperature pressure gauge is in contact with the outside world, or an oil bag is used for oil sealing; one end of the fluorescent fiber optic high temperature pressure gauge is connected to one end of the logging optical cable, and is sealed and fixed in a metal part. The wellhead end of the logging optical cable is connected to the demodulation host. At the same time, the connection between the fiber optic high temperature pressure gauge and the transmission optical cable end downhole and the outer shell of the fiber optic high temperature pressure gauge are sealed in a metal tube;

[0103] The measuring step includes a temperature measuring step and a pressure measuring step.

[0104] The pulse pump laser generator in the host is output through the fiber coupler, and the returned signal is also input into the fluorescence time domain signal acquisition module through the fiber coupler, and the fluorescence wavelength demodulation module performs data processing. The temperature measurement step finally outputs the ambient temperature of the fiber optic high temperature pressure gauge through the fluorescence time domain signal acquisition module; the pressure measurement step outputs the pressure information of the fiber optic high temperature pressure gauge environment through the fluorescence wavelength demodulation module.

[0105] Specifically, in the pressure measurement step, the demodulation host outputs pulse pump light which is input into the optical fiber through the transmission optical cable and finally input into the pump optical gain medium, thereby generating fluorescence; after the fluorescence is output to the optical interference high-voltage detection module, it is returned to the demodulation host at the wellhead through the transmission optical cable; the downhole pressure value is obtained by simulating the change of the arm length difference between the interference optical cavity and the interference optical cavity of the optical fiber high-temperature pressure gauge;

[0106] In the temperature measurement step, the demodulation host divides the optical signal into two parts, one part measures the fluorescence lifetime of the returned optical signal, and the other part measures the interference fringes of the returned optical signal; when the optical fiber high-temperature pressure gauge is affected by the ambient temperature, the returned fluorescence lifetime will change, the higher the temperature, the shorter the fluorescence lifetime will be, and the lower the temperature, the longer the fluorescence lifetime will be; when the pulse output pump light is input to the gain medium, the optical power of the pulse pump light is sufficient for the fluorescence saturation output of the gain medium; when the gain medium has no pump light, the fluorescence will continue to output and then decay rapidly, and the decay time is related to the ambient temperature; by using the pulse signal as the trigger signal, the fluorescence lifetime of the gain medium in the demodulation host and the gain medium of the optical fiber high-temperature pressure gauge is accumulated multiple times and measured at the same time, and the temperature value of the optical fiber high-temperature pressure gauge can be obtained by comparative calculation.

[0107] The present invention adopts the above scheme to implement the measurement system based on the optical fiber high temperature pressure gauge, which mainly includes a downhole temperature measurement part and a downhole pressure measurement part. The temperature measurement part is mainly realized by the optical gain medium located between the high temperature optical fiber collimator and the Fabry-Perot interferometer cavity; the pressure measurement part is mainly measured by the fluorescence generated by the optical gain medium in the Fabry-Perot interferometer cavity to generate light wavelength interference. The temperature measurement part and the downhole pressure measurement part are both sealed in a metal shell. The entire measurement system can realize simultaneous measurement of temperature and pressure.

[0108] Among them, downhole temperature detection directly measures the ambient temperature through the fluorescence lifetime measurement generated by the optical gain medium. Downhole pressure detection directly measures the ambient pressure through the change in cavity length caused by the external pressure on the Fabry-Perot interferometer cavity. Both temperature detection and pressure detection are measured through fluorescence, which are both achieved through optical gain media, without the need for two sets of devices, and have the advantages of simple structure and ingenious construction.

[0109] In specific implementation, one end of the fiber optic high-temperature pressure gauge is connected to one end of the logging optical cable and sealed and fixed in the metal part. The wellhead end of the logging optical cable is connected to the demodulation host of the fluorescence fiber optic high-temperature pressure gauge. The pulse pump laser generator in the demodulation host is output through the fiber optic coupler, and the returned signal is also input to the fluorescence time domain signal acquisition module through the fiber optic coupler, and the fluorescence wavelength demodulation module performs data processing. The fluorescence time domain signal acquisition module finally outputs the ambient temperature of the fiber optic high-temperature pressure gauge; the fluorescence wavelength demodulation module outputs the pressure information of the environment of the fiber optic high-temperature pressure gauge.

[0110] When installing the fluorescent fiber optic high-temperature pressure gauge, first fix the fluorescent fiber optic high-temperature pressure gauge to the downhole end of the logging optical cable; then connect the other end of the logging optical cable to the demodulation host of the fluorescent fiber optic high-temperature pressure gauge; measure the returned fluorescence lifetime through the fluorescence time domain module in the demodulation host, and after data processing, the temperature information of the downhole detection point can be obtained; detect the returned fluorescence interference spectrum through the fluorescence wavelength demodulation module in the demodulation host, and after data processing, the pressure information of the downhole detection point can be obtained.

[0111] In addition, the dual-channel signal acquisition module can be realized through an acquisition card, and the temperature measurement accuracy of the downhole detection point can be improved by increasing the acquisition rate of the acquisition card; the pressure value of the downhole detection point is calculated by the total amount of optical interference fringe phase.

[0112] The measurement system and method implemented by the present invention through the above scheme can realize temperature measurement and pressure measurement under high temperature conditions underground. Since the optical parts are not in contact with external stress, the reliability and stability of underground temperature and pressure measurement are greatly improved.

[0113] It should be emphasized that the term “include / comprises” when used herein refers to the presence of features, elements, steps or components, but does not exclude the presence or addition of one or more other features, elements, steps or components.

[0114] Although the present invention has been disclosed above by describing specific embodiments of the present invention, it should be understood that all the above embodiments and examples are exemplary rather than restrictive. Those skilled in the art may design various modifications, improvements or equivalents of the present invention within the spirit and scope of the appended claims. These modifications, improvements or equivalents should also be considered to be included in the protection scope of the present invention.

Claims

1. A measurement system of a fluorescence optical fiber high temperature pressure gauge, characterized in that: It includes an optical fiber high temperature pressure meter for collecting downhole pressure and temperature, a demodulation host for outputting pulse pump light to the optical fiber high temperature pressure meter and receiving feedback signals, and a transmission optical cable for connecting the optical fiber high temperature pressure meter and the demodulation host; The optical fiber high temperature pressure gauge comprises a temperature measuring part and a pressure measuring part; The demodulation host comprises a pump laser generating device for outputting pulsed pump light to the optical fiber high temperature pressure gauge, an interference demodulation module for simulating an interference optical cavity, and a temperature demodulation module for obtaining a fluorescence lifetime curve. The simulated interference optical cavity of the interference demodulation module has the same configuration as the interference optical cavity of the pressure measuring part of the optical fiber high temperature pressure gauge, and the temperature demodulation module has the same gain medium as the temperature measuring part of the optical fiber high temperature pressure gauge. The pump laser generating device of the demodulation host divides the signal into two identical paths, one of which is transmitted to the optical fiber high-temperature pressure meter downhole, and the other is transmitted to the interference demodulation module and the temperature demodulation module. The downhole pressure value is obtained by simulating the change of the arm length difference between the interference optical cavity and the interference optical cavity of the optical fiber high-temperature pressure meter, and the downhole temperature value is obtained by comparing the fluorescence lifetime curve of the temperature demodulation module with the fluorescence lifetime curve of the received optical fiber high-temperature pressure meter.

2. The measuring system of the fluorescence type optical fiber high temperature pressure gauge according to claim 1, characterized in that: The fiber optic high temperature pressure gauge comprises a fiber optic collimator and a pump optical gain medium for temperature measurement, and an optical interference high-voltage detection module for pressure measurement. One end of the fiber optic collimator is connected to the pump optical gain medium and the optical interference high-voltage detection module in sequence, and the other end of the fiber optic collimator is connected to the transmission optical cable and the demodulation host in sequence. The optical interference arm length difference of the optical interference high-voltage detection module is linearly related to the external pressure. When the external pressure acts on the optical interference high-voltage detection module, the optical interference arm length difference changes, and the analog interference optical cavity of the demodulation host is used for comparison, so as to demodulate the external pressure value. After the pulsed pump light is input through the transmission optical cable, the pump optical gain medium generates a fluorescence effect of spontaneous radiation, and the temperature demodulation module of the demodulation host calculates the temperature value by comparing the received fluorescence lifetime curve with the preset fluorescence lifetime curve.

3. The measuring system of the fluorescence type optical fiber high temperature pressure gauge according to claim 2, characterized in that: The input light source of the optical interference high-voltage detection module is a fluorescent broadband light source generated after the pulse pump light passes through the pump optical gain medium.

4. The measuring system of the fluorescence type optical fiber high temperature pressure gauge according to claim 2, characterized in that: The optical interference high-pressure detection module is located on the end face or side face of the optical fiber high-temperature pressure gauge.

5. The measuring system of the fluorescence type optical fiber high temperature pressure gauge according to claim 2, characterized in that: The optical interference of the optical interference high-voltage detection module is Fabry-Perot interference, Michelson interference or Mach-Zehnder interference.

6. The measuring system of the fluorescence type optical fiber high temperature pressure gauge according to claim 1, characterized in that: The optical fiber high temperature pressure gauge comprises a housing, a high temperature optical fiber, a high temperature optical fiber collimator, an optical fiber collimator seal, a first optical gain medium and a Fabry-Perot interferometer cavity. The housing seals the high temperature optical fiber collimator, the first optical gain medium and the Fabry-Perot interferometer cavity through the optical fiber collimator seal. The end face of the optical fiber high temperature pressure gauge is the stress face of the Fabry-Perot interferometer cavity for stress detection.

7. The measuring system of the fluorescence type optical fiber high temperature pressure gauge according to claim 6, characterized in that: The demodulation host comprises a broadband filter, a first coupler, a second coupler, a third coupler, a pulse pump generator, a fluorescence time-domain signal acquisition module and a fluorescence wavelength demodulation module. The fluorescence time-domain signal acquisition module comprises a second fiber collimator, a second optical gain medium, a first photoelectric conversion module, a second photoelectric conversion module and a signal acquisition processing module; the fluorescence wavelength demodulation module comprises a third fiber collimator, an analog light interference cavity, a PZT piezoelectric ceramic, a third photoelectric conversion module and a dual-channel signal acquisition module; the broadband filter, the first coupler and the pulse pump generator are connected in sequence, the first coupler and the second coupler are connected to each other, the second optical gain medium, the second fiber collimator, the second coupler and the first photoelectric conversion module are connected in sequence, the broadband filter, the third coupler and the second photoelectric conversion module are connected in sequence, the first photoelectric conversion module and the second photoelectric conversion module are both connected to The first optical fiber is connected to the optical fiber high temperature pressure gauge through the first coupler, and the second optical fiber is connected to the second optical fiber collimator and the second optical gain medium through the first coupler and the second coupler to generate fluorescence. The generated fluorescence is converted into an electrical signal through the first photoelectric conversion module. The two fluorescences are simulated and calculated to finally obtain the lifetime of the fluorescence returned by the optical fiber high temperature pressure gauge. The pump light of the pulse pump generator is split through the first coupler to the Fabry-Perot interference cavity of the optical fiber high temperature pressure gauge to form a broadband light with fluorescence interference fringes. The broadband light returns to the transmission cable via the optical fiber and enters the fluorescence wavelength demodulation module through the broadband filter. The returned interference light passes through the third fiber collimator and the simulated light interference cavity, and then the length of the Fabry-Perot interference cavity after being subjected to pressure is measured through the cavity length of the PZT piezoelectric ceramic, thereby obtaining the external pressure.

8. The measuring system of the fluorescence type optical fiber high temperature pressure gauge according to claim 7, characterized in that: The second optical gain medium has the same size and material as the first optical gain medium.

9. A method for measuring a fluorescence optical fiber high temperature pressure gauge, applied to a measurement system of a fluorescence optical fiber high temperature pressure gauge according to any one of claims 1 to 8, characterized in that: include: Installation steps: First, fix the fluorescent fiber optic high temperature pressure gauge to the lower end of the transmission optical cable; then connect the other end of the transmission optical cable to the demodulation host of the fluorescent fiber optic high temperature pressure gauge: Pressure measurement steps: The demodulation host outputs pulse pump light which is input into the optical fiber through the transmission optical cable and finally input into the pump optical gain medium, thereby generating fluorescence; after the fluorescence is output to the optical interference high-voltage detection module, it is returned to the demodulation host at the wellhead through the transmission optical cable; the downhole pressure value is obtained by simulating the change in the arm length difference between the interference optical cavity and the interference optical cavity of the optical fiber high-temperature pressure gauge; Temperature measurement steps: The demodulation host divides the optical signal into two parts, one part measures the fluorescence lifetime of the returned optical signal, and the other part measures the interference fringes of the returned optical signal; when the optical fiber high-temperature pressure gauge is affected by the ambient temperature, the returned fluorescence lifetime will change. The higher the temperature, the shorter the fluorescence lifetime will be, and the lower the temperature, the longer the fluorescence lifetime will be; when the pulse output pump light is input to the gain medium, the optical power of the pulse pump light is sufficient for the fluorescence saturation output of the gain medium; when the gain medium has no pump light, the fluorescence will continue to output and then decay rapidly, and the decay time is related to the ambient temperature; by using the pulse signal as the trigger signal, the fluorescence lifetime of the gain medium in the demodulation host and the gain medium of the optical fiber high-temperature pressure gauge is accumulated multiple times and measured at the same time, and the temperature value of the optical fiber high-temperature pressure gauge can be obtained by comparative calculation.

10. The measuring method of the fluorescence type optical fiber high temperature pressure gauge according to claim 9, characterized in that: The connection between the optical fiber high temperature pressure gauge and the transmission optical cable end downhole and the outer shell of the optical fiber high temperature pressure gauge are sealed in a metal tube.

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