CN213838682U - Optical fiber sensing safety monitoring system suitable for oil field enterprises - Google Patents

Abstract

The utility model discloses an optical fiber sensing safety monitoring system suitable for oil field enterprise, it includes: the method comprises the following steps: the ultra-narrow linewidth laser light source assembly is connected with the coupler, a first output end of the coupler is connected with the acousto-optic regulator, and a second output end of the coupler is connected with the balance detector; the acousto-optic regulator is connected with a first optical fiber amplifier, the first optical fiber amplifier is connected with an optical fiber circulator, the optical fiber circulator is respectively connected with a sensing optical fiber and a second optical fiber amplifier, and the second optical fiber amplifier is connected with a balance detector; the balance detector is connected to the filter, and the filter is connected to the acquisition unit. The balanced detector is added in the scheme, so that the signal linearity of the system can be greatly improved, and the overall detection accuracy of the system is improved.

Description

Optical fiber sensing safety monitoring system suitable for oil field enterprises

Technical Field

The utility model relates to a safety precaution technique, concretely relates to intelligence optical fiber sensing safety precaution technique based on distributed optical fiber sensing technique.

Background

The oil field enterprises have many points, long lines, wide faces, and many remote zones, and the production area has villages, towns and villages, which has complex civil conditions, large prevention difficulty, and is easy to be stolen, damaged, and even terrorist attack. The production area of multiple devices and the management office area where high-value articles are concentrated are likely targets of attack and destruction, and are important areas for security. However, the technical precaution measures applied by oil field enterprises are extremely unbalanced in development and greatly different in investment, a unified, stable, convenient and effective technological protection system is not formed, and the technical precaution construction needs to be further strengthened. Meanwhile, oil field application products have special requirements on fire prevention and explosion prevention, and technical protection products have good adaptability to the application environment of the oil field. The comprehensive safety monitoring system with advanced technology, stable and reliable performance and strong adaptability is required to be equipped.

Because the environment of oil field enterprises is complex mostly, especially under the condition that the natural environment is mixed with the production environment, the background noise is complex, the noise is an unfavorable condition for preventing people from analyzing the optical fiber vibration signal, and the introduction of the noise is inevitable. In the process of collecting all-line signals and collecting target signals, the distributed optical fiber system can also collect a large amount of natural environment noise, production environment noise and the like. The introduction of noise can change the vibration source signal into a noise-containing signal, which can affect the signal extraction real characteristics, so that the continuous optimization and improvement of the system signal-to-noise ratio are the basis for providing a high-quality signal for system analysis. However, a difficulty that the system can hardly solve in obtaining high precision is the phenomenon of birefringence, similar to the concept that the human eye may generate astigmatism, because the propagation direction of light is a transverse wave, the requirement of forward transmission is that the radial surface of the optical fiber is absolutely circular, but in reality, it is difficult to ensure the absolute circle, so that the propagation direction of light perpendicular to the propagation of vibration may form an off-normal state in two directions of X, Y axes, and thus the phenomenon of birefringence occurs during the propagation of light. The two partial normalities are not fixed and will weaken the interference signal when the interference is performed.

Therefore, how to effectively improve the detection accuracy of the distributed optical fiber sensing system is an urgent problem to be solved in the field.

SUMMERY OF THE UTILITY MODEL

To the problem that the safety monitoring scheme that has for oil field enterprise exists, the utility model aims at providing an optic fibre sensing safety monitoring system who is applicable to oil field enterprise, can improve the system to the discernment rate of accuracy that the perimeter intrusion was surveyed to overcome the problem that prior art exists.

In order to achieve the above object, the utility model provides an optical fiber sensing safety monitoring system suitable for oil field enterprise, include: the ultra-narrow linewidth laser light source assembly is connected with the input end of the coupler, the first output end of the coupler is connected with the input end of the acousto-optic regulator, and the second output end of the coupler is connected with the input end of the balance detector; the output end of the acousto-optic regulator is connected with the input end of a first optical fiber amplifier, the output end of the first optical fiber amplifier is connected with the input end of an optical fiber circulator, the optical fiber circulator is respectively connected with the input ends of a sensing optical fiber and a second optical fiber amplifier, and the output end of the second optical fiber amplifier is connected with the input end of a balance detector; the output end of the balance detector is connected to the input end of the filter, and the output end of the filter is connected to the acquisition unit.

Further, the laser light source component adopts an ultra-narrow linewidth semiconductor laser.

Further, the first optical fiber amplifier and/or the second optical fiber amplifier are erbium-doped optical fiber amplifiers.

Furthermore, the optical fiber sensing safety monitoring system also comprises a modulator driver, and the modulator driver is in driving connection with the acousto-optic regulator.

The utility model provides a scheme founds distributed optical fiber sensing system based on the balancer technique, measures through improving inclined to the positive attitude, adds the balanced type detector to can improve the signal linearity of system greatly, the holistic detection degree of accuracy of lift system can improve the system then and to the discernment rate of accuracy that the perimeter invasion was surveyed.

Drawings

The invention is further described with reference to the following drawings and detailed description.

Fig. 1 is a diagram illustrating an example of an optical path structure of a safety monitoring system based on optical fiber sensing according to the present embodiment;

FIG. 2 is a diagram illustrating an exemplary optical path structure of the distributed optical fiber sensing system based on the balancer in this example;

fig. 3 is a schematic diagram of a balanced detector in this example.

Detailed Description

In order to make the technical means, creation features, achievement purposes and functions of the present invention easy to understand and understand, the present invention is further explained by combining with the specific drawings.

The embodiment utilizes the sensing optical cable as a sensing transmission medium and is an optical fiber sensing safety early warning system based on the distributed optical fiber sensing technology.

Referring to fig. 1, there is shown an example of the configuration of a security monitoring system based on optical fiber sensing in this example.

As can be seen from the figure, the security monitoring system 10 is mainly formed by matching a main control board 11, an ultra-narrow linewidth laser module 12, an acousto-optic modulator 13, an optical fiber amplifier 14, a coupler 15, a circulator 16, a sensing optical fiber 17 and a photodetector 18.

The main control board 11, the ultra-narrow linewidth laser module 12, the acousto-optic modulator 13 and the optical fiber amplifier 14 are matched to form a light source assembly.

Specifically, the main control board 11 controls and connects the ultra-narrow linewidth laser module 12, the acousto-optic modulator 13 and the optical fiber amplifier 14, and the ultra-narrow linewidth laser module 12, the acousto-optic modulator 13 and the optical fiber amplifier 14 are connected in sequence.

Further, the output of the fiber amplifier 14 is connected to a circulator 16 through a coupler 15, and the circulator 16 is connected to a sensing fiber 17 and a photodetector 18, respectively. The photodetector 18 is connected to the main control board 11.

In specific implementation, the main control board 11 is formed by matching a corresponding FPGA with an ARM. While the photodetector 18 is constituted by a corresponding detection plate.

The light source adopted by the safety monitoring system formed by the method is a narrow linewidth laser light source. Continuous light generated by the light source is modulated into narrow pulses through the intensity modulator, and Rayleigh scattered light is injected into the sensing optical fiber through the optical fiber circulator and then is injected into the photoelectric detector from the other end of the optical fiber circulator for detection. Because the pulse light injected into the sensing optical fiber has super-strong coherence, the returned Rayleigh reflected light also has super-strong coherence, and the photoelectric detector receives the interference light intensity of backward Rayleigh new scattered light within the pulse width.

When the system is in operation, when the frequency of the laser light source does not drift and the sensing optical fiber is not disturbed, the phase of the backward Rayleigh scattering light along the optical fiber cannot be changed, so that the time domain curves of the collected backward Rayleigh scattering light intensity are kept consistent. When a certain position of the optical fiber is disturbed, the optical fiber at the corresponding position is deformed, the refractive index, the length and the radius of the optical fiber are changed, and the backward Rayleigh scattering rate and the backward Rayleigh scattering light phase at the position are correspondingly changed. Due to the strong coherence of the injection pulse light of the system, the interference effect is very obvious, and the system is very sensitive to the amplitude and phase change of the backward rayleigh scattering light. And obtaining external disturbance information by demodulating the amplitude and phase changes of the backward Rayleigh scattering light.

On the basis, the embodiment realizes the improvement of the measurement of the off-normal state by adding the balance detector, and then constructs a safety monitoring system with high sensitivity and good signal-to-noise ratio.

Referring to fig. 2, an exemplary configuration of the distributed fiber optic sensing system based on balancers is shown in this example.

As can be seen from the figure, the distributed optical fiber sensing system 100 is mainly formed by mutually matching an ultra-narrow linewidth semiconductor laser 101, an optical fiber coupler 102, an acousto-optic modulator AOM 103, a driver 104, a first erbium-doped optical fiber amplifier 105, an optical fiber circulator 106, a sensing optical fiber 107, a second erbium-doped optical fiber amplifier 108, a balanced detector 109, a filter 110, and a high-speed data acquisition unit 111.

The ultra-narrow linewidth semiconductor laser 101 constitutes a light source assembly of the whole system, and the output end of the ultra-narrow linewidth semiconductor laser is connected with the input end of the optical fiber coupler 102.

The output end of the optical fiber coupler 102 forms two paths of output, and a first output light path is connected with the input end of the acousto-optic modulator AOM 103; the second output optical path is connected to the input of the balanced detector 109.

Preferably, the first output optical path and the second output optical path formed by the fiber coupler 102 have an output power ratio of 9:1, but not limited thereto.

The output of AOM 103 is connected to the input of a first erbium doped fiber amplifier 105, and the output of the first erbium doped fiber amplifier 105 is connected to a fiber circulator 106.

Here a fibre circulator 106 is connected to the input of a sensing fibre 107 and a second erbium doped fibre amplifier 108. The output of the second erbium doped fiber amplifier 108 is connected to the input of a balanced detector 109.

The output of the balance detector 109 is connected to the input of a filter 110, and the output of the filter 110 is connected to a high speed data acquisition unit 111.

The driver 104 in the present system is preferably a corresponding driving circuit, and is connected to the AOM 103 for driving the AOM 103. The specific structure of the driving circuit can be determined according to actual requirements, and is not described herein.

The consistency of two photodiodes and auxiliary circuits of the balance detector adopted in the system is as high as possible; the light beam gains gain during the mixing process of coherent detection, which is equivalent to a noise-free optical amplifier.

By way of example, the structure of the balanced detector in this example adopts two structures, namely, two photodiodes are connected in series, the middle tap of each photodiode is connected with TIA, each diode is connected with a trans-impedance amplifier (TIA), and then the two structures are connected in parallel.

As shown in fig. 3, it is a schematic diagram of a balanced detector formed by connecting each diode with a trans-impedance amplifier (TIA) in parallel.

As shown in the figure, the balanced detector with the structure is formed by adding the same bias to the two PIN detectors with TIAs respectively, the same-direction end PD1+ of the differential output of one TIA and the reverse-direction end PD 2-of the differential output of the other TIA are coupled through the mixer magic T to be used as the same-direction end input of the limiting amplifier, and the other end of the differential output of the TIA also enters the coupler in the reverse mode to be used as the reverse-direction input end of the limiting amplifier.

The distributed optical fiber sensing system based on the balancer is formed by adopting an ultra-narrow linewidth laser module CW to send out detection continuous light, the detection continuous light passes through a band-pass filter, filtered pulse signals form two paths of light source outputs through a coupler, one path of light source signal output enters an acousto-optic modulator AOM for pulse external modulation, the modulated pulse signals enter a first erbium-doped optical fiber amplifier for amplification, then enter a sensing optical fiber after passing through an optical fiber circulator, and the sensing optical fiber is coherent with returned backward Rayleigh scattering signals; coherent signals enter a first erbium-doped fiber amplifier for amplification, the amplified signals and another path of light source signals formed by the coupler simultaneously enter a balance detector, are processed by the balance detector, are filtered by a filter, and then enter a high-speed data acquisition unit.

The distributed optical fiber sensing system based on the balancer can effectively improve the sensitivity of the system through the structure of the balancer, obviously reduce the noises of electronic circuits and detectors, greatly improve the signal linearity of the system and improve the overall detection accuracy of the system.

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the above embodiments, and that the foregoing embodiments and descriptions are provided only to illustrate the principles of the present invention without departing from the spirit and scope of the present invention. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (4)

1. Optical fiber sensing safety monitoring system suitable for oil field enterprise, its characterized in that includes: the device comprises a laser light source assembly, a coupler, an acousto-optic regulator, a first optical fiber amplifier, an optical fiber circulator, a sensing optical fiber, a second optical fiber amplifier, a balance detector, a filter and an acquisition unit, wherein the laser light source assembly is connected with the input end of the coupler, the first output end of the coupler is connected with the input end of the acousto-optic regulator, and the second output end of the coupler is connected with the input end of the balance detector; the output end of the acousto-optic regulator is connected with the input end of a first optical fiber amplifier, the output end of the first optical fiber amplifier is connected with the input end of an optical fiber circulator, the optical fiber circulator is respectively connected with the input ends of a sensing optical fiber and a second optical fiber amplifier, and the output end of the second optical fiber amplifier is connected with the input end of a balance detector; the output end of the balance detector is connected to the input end of the filter, and the output end of the filter is connected to the acquisition unit.

2. The fiber optic sensing security monitoring system of claim 1, wherein the laser light source assembly employs an ultra-narrow linewidth semiconductor laser.

3. The fiber sensing security monitoring system of claim 1, wherein the first fiber amplifier and/or the second fiber amplifier is an erbium doped fiber amplifier.

4. The optical fiber sensing safety monitoring system according to claim 1, further comprising a modulator driver, wherein the modulator driver is in driving connection with the acousto-optic modulator.

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