Sound wave optical fiber sensor for testing sand content of oil and gas pipeline

Abstract

The invention discloses an oil and gas pipeline sand content test sound wave optical fiber sensor, and particularly relates to the technical field of sensors, which comprises a rare earth doped silicon dioxide optical waveguide sheet, a vibration transduction structure, a phase shift waveguide grating and a phase shift wave. The device further comprises a photoelectric converter, a signal amplifier, a filter, a fragrance clamping filter and a vibration signal detector. The rare earth doped silicon dioxide waveguide sheet is located on the vibration transduction structure, and the phase shift waveguide grating is inscribed in the rare earth doped silicon dioxide waveguide sheet. The micro-vibration optical chip sensor based on the photoacoustic spectrum is simple and firm in structure, easy to manufacture and convenient to integrate with other systems, and the problem of integration of a traditional optical fiber distributed sensing system can be effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of sensors, in particular to an acoustic wave optical fiber sensor for testing sand content in oil and gas pipelines. Background Art

[0002] With the development of new energy, countries around the world are paying more and more attention to the development and utilization of unconventional natural gas, especially shale gas. At present, my country is conducting resource evaluation of shale gas nationwide. my country's shale gas production capacity is constantly increasing. my country's Great Wall Station generally uses sand-added hydraulic fracturing technology. After fracturing is completed and production begins, a large amount of fracturing fluid and solid particles (quartz sand and ceramsite) injected into the formation will be returned to the ground gathering and transportation system, causing serious scouring and corrosion problems. At the same time, the sand particles returned to the top are weighed and analyzed to observe the changes in the rock formation, and the changes in the rock formation are analyzed according to the sand production situation.

[0003] Traditional sand flow detection uses electromagnetic and pulse methods, sampling and weighing methods, etc. Currently, sampling and weighing methods on the market account for 80% of the total, but such methods are not satisfactory in use, mainly because the sand is very fine and the content cannot be obtained by sampling. Among them, the acoustic wave online pipeline sampling method and the optical fiber acoustic wave probe are widely used in the field of pipeline measurement. The vibration effect of the external vibration signal on the inner membrane of the optical fiber can be used to measure the size of the external vibration signal. It has high sensitivity and accuracy, but the optical fiber itself is relatively fragile. In the application of micro-vibration measurement, it has high transducer packaging requirements. The combination of optical fiber and transducer packaging structure is often difficult and requires a high level of process, which increases the cost of the sensor. The combination of the traditional optical waveguide structure and the transducer structure used for micro-vibration detection is often a pasting combination, and its structural stability is poor, which is not suitable for long-term pipeline detection.

[0004] The main components of the existing technology: ultrasonic sensors, which are collection sensors based on conduction transmission, are used to detect the degree of wear of sand and gravel on the pipe wall, and then analyze the particles of sand and gravel. Analyze the number of impacts on the pipe wall, and then analyze the life of the pipe, targeting the elbow part of the pipe wall.

[0005] In view of the defects of the prior art, the purpose of the present invention is to provide a sensor for ultrasonically detecting the wear state of pipe wall and the size of particles, aiming to solve the problems of poor integration of existing micro-vibration sensors and poor stability of pulse sensors. Summary of the invention

[0006] The object of the present invention is to provide an acoustic fiber optic sensor for testing sand content in oil and gas pipelines to solve the problems in the current market raised by the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions: a method for manufacturing an acoustic fiber sensor for testing sand content in oil and gas pipelines, comprising a rare earth doped silica optical waveguide sheet, a vibration transducer structure, a phase shift waveguide grating, and a phase shift wave;

[0008] It also includes a photoelectric converter, a signal amplifier, a filter, an aroma clamp filter and a vibration signal detector;

[0009] The rare earth doped silicon dioxide microwave guide sheet is located on the vibration transducer structure, and the phase shift waveguide grating is engraved in the rare earth doped silicon dioxide optical waveguide sheet;

[0010] Preferably, the rare earth doped silica optical waveguide sheet is a three-layer waveguide layer structure, the light guiding layer is rare earth doped silica, and the cladding layer is undoped pure silica.

[0011] Preferably, the phase shift amount of the phase-shift waveguide grating is π, and as the resonant cavity of the optical waveguide laser, the external pump laser generates ultra-narrow linewidth laser after passing through the phase-shift waveguide grating.

[0012] Preferably, the vibration transducer structure is a chip-type substrate structure, and the strongest vibration point thereof corresponds to the π phase shift position of the phase-shift waveguide grating;

[0013] The vibration transducer structure is a sheet-type substrate structure, and the strongest vibration point thereof corresponds to the optical fiber tail of the phase-shifted wave.

[0014] Preferably, the vibration transducer structure is used as a substrate for a rare earth doped silica optical waveguide, and a rare earth doped silica optical waveguide sheet is produced on the vibration transducer structure by an MCVD process.

[0015] Preferably, the phase-shift waveguide grating is written on the light-guiding layer on the rare-earth-doped silicon dioxide optical waveguide sheet using UV photolithography technology.

[0016] Preferably, when the pump light is incident on a rare earth-doped silicon dioxide optical waveguide sheet engraved with a phase-shift waveguide grating structure, an ultra-narrow linewidth laser will be generated.

[0017] Preferably, the external micro-vibration signal is transmitted to the rare earth-doped silica optical waveguide sheet through the vibration transducer structure, and the vibration sensing detection is realized by using external light phase detection.

[0018] A method for manufacturing an acoustic fiber optic sensor for testing sand content in an oil and gas pipeline comprises the following steps:

[0019] Firstly, the mocvd process is used to generate a rare earth doped silica optical waveguide on the vibration transducer structure. After the optical waveguide is generated, UV lithography technology is used to transmit the peak signal value once on the rare earth doped silica optical waveguide. Each vibration can generate a corresponding peak signal.

[0020] Preferably, the vibration transducer structure generates a rare earth-doped silica optical waveguide sheet by generating two layers of pure silica and one layer of rare earth-doped silica, and the generation order is one layer of pure silica, one layer of rare earth-doped silica, and one layer of pure silica;

[0021] The mask used in UV lithography is a phase-shift grating mask.

[0022] Compared with the prior art, the beneficial effects of the present invention are: the micro-vibration optical chip sensor based on photoacoustic spectroscopy provided by the present invention has a simple and firm structure, is easy to manufacture, and is convenient for integration with other systems, and can effectively solve the integration problem of traditional optical fiber distributed sensing systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the structure of the present invention;

[0024] Figure 2 Schematic diagram of the sensing system of the present invention.

[0025] In the figure: 1. Rare earth doped silica optical waveguide; 2. Vibration transducer structure; 3. Phase shift waveguide grating; 4. Phase shift wave; 5. Photoelectric converter; 6. Signal amplifier; 7. Filter; 8. Phase clamp filter; 9. Vibration signal detector. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] A method for manufacturing an acoustic fiber optic sensor for testing sand content in oil and gas pipelines comprises a rare earth doped silicon dioxide optical waveguide sheet 1, a vibration transducer structure 2, and a phase shift waveguide grating 3.

[0028] like Figure 1 The shown embodiment is a distributed feedback optical waveguide laser micro-vibration optical chip sensor, wherein a rare earth doped silicon dioxide optical waveguide sheet 1 is generated on a vibration transducer structure 2 by a mocvd process, and a phase shift waveguide grating 3 is engraved on the rare earth doped silicon dioxide optical waveguide sheet 1 by UV lithography technology.

[0029] Specifically, the rare earth doped silica optical waveguide sheet 1 is a three-layer waveguide layer structure, the light guiding layer is rare earth doped silica, and the cladding layer is undoped pure silica.

[0030] Specifically, the phase shift amount of the phase-shift waveguide grating 3 is π, and as a resonant cavity of an optical waveguide laser, an external pump laser generates an ultra-narrow linewidth laser after passing through the phase-shift waveguide grating 3 .

[0031] Specifically, the vibration transducer structure is a chip-type substrate structure, and the strongest vibration point thereof corresponds to the π phase shift position of the phase-shift waveguide grating 3 .

[0032] Specifically, the vibration transducer structure is a sheet-type substrate structure, and the strongest vibration point corresponds to the optical fiber tail of the phase shift wave 4.

[0033] like Figure 2 The schematic diagram of the optical chip sensing system in the example of the present invention is shown, the photoelectric converter 5 generates a pump laser that passes through the signal amplifier 6 and the narrowband filter 7, and the optical fiber passes through the phase-shifted waveguide grating 3 in the signal amplification sensor 6 to generate an ultra-narrow linewidth excitation, and its frequency corresponds to the excitation source of the phase-shifted waveguide grating 3. The output light of the signal amplifier 6 is incident on the external gas to be measured, so that the external gas to be measured is excited to produce an acousto-optic effect, so that the vibration signal detector 9 receives the external weak vibration signal, and the ultra-narrow linewidth laser output frequency drifts. The laser reflected back by the phase-shifted waveguide grating 3 enters the phase clamping filter 8 through the coupler. The filter 7 can be used to convert the drift of the ultra-narrow linewidth laser output frequency into a change in the output light signal intensity. The vibration signal detector 9 receives the change in the output light signal intensity to obtain the external weak vibration signal amount, thereby obtaining the external gas concentration to be measured.

[0034] Specifically, the photoelectric converter 5, the signal amplifier 6 and the filter 7, the phase clamp filter 8 and the vibration signal detector 9 are integrated into a vibration chip to improve the integration of the entire sensing system.

[0035] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for producing an acoustic fiber optic sensor for testing sand content in oil and gas pipelines, characterized in that: It comprises a rare earth doped silicon dioxide optical waveguide plate (1), a vibration transducer structure (2), a phase shift waveguide grating (3), and a phase shift wave (4); It also includes a photoelectric converter (5), a signal amplifier (6), a filter (7), an aroma clamp filter (8) and a vibration signal detector (9); The rare earth doped silicon dioxide microwave guide plate (1) is located on the vibration transducer structure, and the phase shift waveguide grating (3) is engraved in the rare earth doped silicon dioxide optical waveguide plate (1).

2. The acoustic fiber optic sensor for testing sand content in oil and gas pipelines according to claim 1, characterized in that: The rare earth doped silica optical waveguide sheet (1) is a three-layer waveguide layer structure, the light guiding layer is rare earth doped silica, and the cladding layer is undoped pure silica.

3. The acoustic fiber optic sensor for testing sand content in oil and gas pipelines according to claim 1, characterized in that: The phase shift amount of the phase-shift waveguide grating (3) is π, and as a resonant cavity of an optical waveguide laser, external pump laser generates ultra-narrow line width laser after passing through the phase-shift waveguide grating (3).

4. The acoustic fiber optic sensor for testing sand content in oil and gas pipelines according to claim 1, characterized in that: The vibration transducer structure (2) is a chip-type substrate structure, and the strongest vibration point thereof corresponds to the π phase shift position of the phase-shift waveguide grating (3); The vibration transducer structure (2) is a sheet-type base structure, and the strongest vibration point corresponds to the optical fiber tail of the phase shift wave (4).

5. The acoustic fiber optic sensor for testing sand content in oil and gas pipelines according to claim 1, characterized in that: The vibration transducer structure (2) serves as a substrate for a rare earth doped silicon dioxide optical waveguide, and a rare earth doped silicon dioxide optical waveguide sheet (1) is produced on the vibration transducer structure (2) by means of an MCVD process.

6. The acoustic fiber optic sensor for testing sand content in oil and gas pipelines according to claim 1, characterized in that: The phase-shift waveguide grating (3) is written on the light-guiding layer on the rare-earth-doped silicon dioxide optical waveguide plate (1) by using UV photolithography technology.

7. The acoustic fiber optic sensor for testing sand content in oil and gas pipelines according to claim 1, characterized in that: When pump light is incident on a rare earth doped silicon dioxide optical waveguide plate (1) engraved with a phase shift waveguide grating (3) structure, ultra-narrow line width laser light is generated.

8. The acoustic fiber optic sensor for testing sand content in oil and gas pipelines according to claim 1, characterized in that: External micro-vibration signals are transmitted to the rare earth-doped silicon dioxide optical waveguide plate (1) through a vibration transducer structure (2), and vibration sensing detection is achieved by using external light phase detection.

9. A method for manufacturing an acoustic fiber optic sensor for testing sand content in oil and gas pipelines according to any one of claims 1 to 8, characterized in that: The following steps are involved: Firstly, a rare earth doped silicon dioxide optical waveguide sheet (1) is generated on a vibration transducer structure by using a mocvd process. After the optical waveguide sheet is generated, a peak signal value is transmitted once on the rare earth doped silicon dioxide optical waveguide sheet (1) by using UV photolithography technology. Each vibration can generate a corresponding peak signal.

10. The method for manufacturing an acoustic fiber optic sensor for testing sand content in oil and gas pipelines according to claim 7, characterized in that: The vibration transducer structure (2) generates the rare earth doped silicon dioxide optical waveguide (1) by generating two layers of pure silicon dioxide and one layer of rare earth doped silicon dioxide, the generation order being one layer of pure silicon dioxide, one layer of rare earth doped silicon dioxide, and one layer of pure silicon dioxide; The mask used in UV lithography is a phase-shift grating mask.

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