Pipeline path three-dimensional detection reconstruction method and system based on Bragg fiber grating
阅读说明：本技术 基于布喇格光纤光栅的管道路径三维检测重构方法及系统 (Pipeline path three-dimensional detection reconstruction method and system based on Bragg fiber grating ) 是由 袁银权 于 2020-07-23 设计创作，主要内容包括：本发明公开了一种基于布喇格光纤光栅的管道路径三维检测重构方法及系统,其中系统包括宽带光源、第一光分路器、第二光分路器、三维坐标传感探头。宽带光源发出的光经第一光分路器、传导光纤、第二光分路器,入射到三维坐标传感探头上；入射光经三维坐标传感探头反射后,反射光通过第一光分路器输送到波长解调仪；当弹性体轴线偏离重力方向时,引起光纤光栅发生波长漂移,波长解调仪解调出三维坐标传感探头中多个光纤光栅的中心波长,并输送到计算机；计算机根据解调出的中心波长以及光纤光栅应变和曲率分布图,计算钻筒的包括方位角和偏离重力方向的倾角的三维位置坐标。(The invention discloses a pipeline path three-dimensional detection reconstruction method and a pipeline path three-dimensional detection reconstruction system based on Bragg fiber gratings, wherein the system comprises a broadband light source, a first optical splitter, a second optical splitter and a three-dimensional coordinate sensing probe. Light emitted by the broadband light source is incident on the three-dimensional coordinate sensing probe through the first optical splitter, the conducting optical fiber and the second optical splitter; after incident light is reflected by the three-dimensional coordinate sensing probe, reflected light is transmitted to the wavelength demodulator through the first optical splitter; when the axis of the elastic body deviates from the gravity direction, the fiber bragg gratings are caused to generate wavelength drift, and the wavelength demodulator demodulates the central wavelengths of the fiber bragg gratings in the three-dimensional coordinate sensing probe and transmits the central wavelengths to the computer; and the computer calculates the three-dimensional position coordinates of the drill barrel, including the azimuth angle and the inclination angle deviating from the gravity direction, according to the demodulated central wavelength and the fiber bragg grating strain and curvature distribution diagram.)
1. A three-dimensional coordinate sensing probe of a pipeline path based on Bragg fiber gratings is characterized in that the three-dimensional coordinate sensing probe is arranged in a measuring drill cylinder and comprises an elastic body and a mass block, wherein the mass block is fixed at one end of the elastic body, and the other end of the elastic body is fixed on the measuring drill cylinder through a fixed seat; the elastic body is a geometric elastic body with axial symmetry;
a plurality of sensing optical fibers parallel to the axis are uniformly distributed on the surface of the elastomer, each sensing optical fiber is provided with a Bragg fiber grating with a specific central wavelength, and the Bragg fiber grating senses the deformation of the elastomer and the mass block due to the action of gravity.
2. A bragg fiber grating based pipeline path three-dimensional coordinate sensing probe according to claim 1, wherein the three-dimensional coordinate sensing probe further comprises a protective shell covering the exterior of the elastic body and the mass block and fixed by the fixing base, and a closed space is formed between the protective shell and the fixing base.
3. A bragg fiber grating based pipeline path three dimensional coordinate sensing probe according to claim 1 wherein the elastomeric and mass blocks are cylindrical.
4. A bragg fiber grating based pipeline path three-dimensional coordinate sensing probe according to claim 1 wherein a plurality of bragg fiber gratings of different wavelengths are concatenated on each sensing fiber.
5. A three dimensional coordinate sensing probe for a bragg fiber grating-based conduit path as claimed in claim 1 wherein the elastomeric surface is uniformly distributed with 8 sensing fibers parallel to the axis, each identified asb= 1,2, …,8 bragg fiber gratings with different center wavelengths are arranged.
6. A pipeline path three-dimensional detection reconstruction system based on Bragg fiber grating is characterized by comprising a broadband light source, a first optical splitter, a second optical splitter and a three-dimensional coordinate sensing probe, wherein the three-dimensional coordinate sensing probe is the three-dimensional coordinate sensing probe of the pipeline path based on the Bragg fiber grating as claimed in any one of claims 1 to 5;
the broadband light source is connected with one branching port of the first optical branching device; the combining port of the first optical splitter is connected with the combining port of the second optical splitter through a conducting optical fiber; a plurality of branch ports of the second optical splitter are connected with the three-dimensional coordinate sensing probe;
the system also comprises a wavelength demodulator and a computer, wherein the input end of the wavelength demodulator is connected with the other branching port of the first optical branching device; the output end of the wavelength demodulator is connected with the computer through a data line.
7. The bragg fiber grating based pipeline path three-dimensional coordinate sensing probe of claim 6 wherein the first optical splitter is replaced with a circulator.
8. The bragg fiber grating based pipeline path three-dimensional coordinate sensing probe of claim 6 wherein the first optical splitter is a Y-type optical splitter.
9. A method for reconstructing a three-dimensional detection of a pipeline path based on a bragg fiber grating, which is based on the system for reconstructing a three-dimensional detection of a pipeline path based on a bragg fiber grating as claimed in claim 8, and comprises the following steps:
light emitted by the broadband light source is incident on the three-dimensional coordinate sensing probe through the first optical splitter, the conducting optical fiber and the second optical splitter;
after incident light is reflected by the three-dimensional coordinate sensing probe, reflected light is transmitted to the wavelength demodulator through the first optical splitter;
when the axis of the elastic body deviates from the gravity direction, the fiber bragg gratings are caused to generate wavelength drift, and the wavelength demodulator demodulates the central wavelengths of the fiber bragg gratings in the three-dimensional coordinate sensing probe and transmits the central wavelengths to the computer;
and the computer calculates the wavelength drift amount according to the demodulated central wavelength, and then calculates the three-dimensional position coordinates of the drill barrel, including the azimuth angle and the inclination angle deviating from the gravity direction, according to the relationship between the wavelength drift amount and the strain and curvature of the fiber bragg grating.
Technical Field
The invention belongs to the technical field of optical fiber sensing, and relates to a pipeline path three-dimensional detection reconstruction method and system based on Bragg fiber gratings.
Background
In recent years, in order to find low-pressure reservoirs, protect oil and gas reservoirs and improve the recovery ratio in the domestic oil drilling industry, electromagnetic wave wireless measurement while drilling instruments are used in drilling process wells such as directional wells, horizontal wells and the like, and the electromagnetic wave wireless measurement while drilling instruments adopt extremely low frequency (1-20Hz) radio waves as transmission signals and reach the ground through the transmission of strata. However, due to the complex formation condition, the electromagnetic wave wireless measurement while drilling instrument is not ideal in transmission depth and is limited to 2000 meters. The fiber grating sensing technology uses passive devices, and has a series of advantages of intrinsic explosion prevention, electromagnetic interference resistance, corrosion resistance, long transmission distance, suitability for severe environments and the like. Therefore, it is necessary to develop a long-distance pipeline path measuring instrument based on the optical fiber sensing technology.
Disclosure of Invention
The invention aims to solve the technical problem of providing a Bragg fiber grating-based pipeline path three-dimensional detection and reconstruction method and a Bragg fiber grating-based pipeline path three-dimensional detection and reconstruction system which are anti-electromagnetic interference, corrosion-resistant, long in transmission distance and suitable for severe environments, aiming at the defect that the transmission depth of radio waves of an electromagnetic wave wireless measurement while drilling instrument in the prior art is limited.
The technical scheme adopted by the invention for solving the technical problems is as follows:
the three-dimensional coordinate sensing probe is characterized by being arranged inside a measuring drill cylinder and comprising an elastic body and a mass block, wherein the mass block is fixed at one end of the elastic body, and the other end of the elastic body is fixed on the measuring drill cylinder through a fixed seat; the elastic body is a geometric elastic body with axial symmetry;
a plurality of sensing optical fibers parallel to the axis are uniformly distributed on the surface of the elastomer, each sensing optical fiber is provided with a Bragg fiber grating with a specific central wavelength, and the Bragg fiber grating senses the deformation of the elastomer and the mass block due to the action of gravity.
According to the technical scheme, the three-dimensional coordinate sensing probe further comprises a protective shell, the protective shell is covered outside the elastic body and the mass block and fixed through the fixed seat, and a closed space is formed between the protective shell and the fixed seat.
According to the technical scheme, the elastic body and the mass block are cylindrical.
According to the technical scheme, each sensing optical fiber is connected with a plurality of Bragg fiber gratings with different wavelengths in series.
In connection with the above technical solution, 8 sensing fibers, respectively labeled as b 1,2, …,8, are uniformly distributed on the surface of the elastomer, 8 bragg fiber gratings with different center wavelengths are arranged, corresponding to 8 angles,
the invention also provides a pipeline path three-dimensional detection and reconstruction system based on the Bragg fiber grating, which comprises a broadband light source, a first optical splitter, a second optical splitter and a three-dimensional coordinate sensing probe, wherein the three-dimensional coordinate sensing probe is based on the pipeline path of the Bragg fiber grating in the technical scheme;
the broadband light source is connected with one branching port of the first optical branching device; the combining port of the first optical splitter is connected with the combining port of the second optical splitter through a conducting optical fiber; a plurality of branch ports of the second optical splitter are connected with the three-dimensional coordinate sensing probe;
the system also comprises a wavelength demodulator and a computer, wherein the input end of the wavelength demodulator is connected with the other branching port of the first optical branching device; the output end of the wavelength demodulator is connected with the computer through a data line.
In the above technical solution, the first optical splitter is replaced with a circulator.
According to the technical scheme, the first optical splitter is a Y-type optical splitter.
The invention also provides a pipeline path three-dimensional detection and reconstruction method based on the Bragg fiber grating, which is based on the pipeline path three-dimensional detection and reconstruction system based on the Bragg fiber grating in the technical scheme and specifically comprises the following steps:
light emitted by the broadband light source is incident on the three-dimensional coordinate sensing probe through the first optical splitter, the conducting optical fiber and the second optical splitter;
after incident light is reflected by the three-dimensional coordinate sensing probe, reflected light is transmitted to the wavelength demodulator through the first optical splitter;
when the axis of the elastic body deviates from the gravity direction, the fiber bragg gratings are caused to generate wavelength drift, and the wavelength demodulator demodulates the central wavelengths of the fiber bragg gratings in the three-dimensional coordinate sensing probe and transmits the central wavelengths to the computer;
and the computer calculates the wavelength drift amount according to the demodulated central wavelength, and then calculates the three-dimensional position coordinates of the drill barrel, including the azimuth angle and the inclination angle deviating from the gravity direction, according to the relationship between the wavelength drift amount and the strain and curvature of the fiber bragg grating.
The invention has the following beneficial effects: the fiber grating sensing probe is small in size, light in weight and easy to install and use in the drill cylinder; the optical signals are completely adopted in the sensing and transmission area, are electrically insulated, and have the characteristics of intrinsic safety, explosion prevention, lightning protection, electromagnetic interference resistance and the like; and the anti-interference long-distance transmission can be realized by adopting the fiber grating sensing system.
Furthermore, by adopting the wavelength division multiplexing technology, the more accurate detection and reconstruction of the oil well pipeline path can be realized by connecting 8, 16 or even 32 Bragg fiber gratings with different wavelengths in series on one optical fiber.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a schematic structural diagram of a three-dimensional coordinate sensing probe for a pipeline path based on Bragg fiber gratings according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a fiber grating arrangement of a three-dimensional coordinate sensing probe according to an embodiment of the present invention;
FIG. 3 is a schematic structural diagram of a pipeline path three-dimensional detection and reconstruction system based on Bragg fiber gratings according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of the measurement principle in an embodiment of the present invention;
fig. 5 is a flow chart of a pipeline path three-dimensional detection reconstruction method based on bragg fiber gratings according to an embodiment of the present invention.
Wherein, 1: measuring a drill cylinder; 2: an elastomer; 3: a mass block; 4: a fixed seat; 5: FBG # 1; 6: FBG # 2; 7: FBG # 3; 8: FBG # 4; 9:
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In the embodiment of the invention, as shown in fig. 1, the three-dimensional coordinate sensing probe of the pipeline path based on the Bragg fiber grating is arranged in the measuring drill cylinder 1, and the position and the installation angle of the three-dimensional coordinate sensing probe can be changed at will in the measuring drill cylinder according to the requirements. The three-dimensional coordinate sensing probe comprises an elastic body 2 and a mass block 3, wherein the mass block is fixed at one end of the elastic body, and the other end of the elastic body is fixed on a measuring drill cylinder through a fixed seat 4; the elastic body is a geometric elastic body with axial symmetry.
A plurality of sensing optical fibers parallel to the axis are uniformly distributed on the surface of the elastomer, and each sensing optical fiber is provided with a Bragg fiber grating with a specific central wavelength.
When the drill barrel fixed with the elastic body deviates from the gravity direction, the elastic body self weight and the mass block gravity effect cause the deformation of the shape elasticity, and simultaneously, the surface strain is applied to the fiber bragg gratings and causes the synchronous drift of the characteristic wavelengths of the fiber bragg gratings. According to the characteristic wavelength drift of the fiber grating. According to the quantitative relation between the strain and curvature distribution of the plurality of sensing optical fibers of the elastic body and the azimuth angle and the inclination angle of the measuring drill cylinder, the three-dimensional position coordinates including the inclination angle and the azimuth angle of the measuring drill cylinder can be calculated.
Further, the three-dimensional coordinate sensing probe further comprises a protective shell 15, the protective shell is covered outside the elastic body and the mass block and fixed through the fixed seat 4, and a closed space is formed between the protective shell and the fixed seat.
In the embodiment shown in fig. 1, the elastic body and the mass block are both cylindrical. The types of the materials of the elastic body and the mass block can be replaced at will according to the needs. Any other geometric elastomer with axisymmetric characteristics may be substituted as desired.
In other embodiments of the present invention, each sensing fiber is connected with a plurality of bragg fiber gratings with different wavelengths in series. The type and number of the fiber gratings can be adjusted according to the requirement.
In a preferred embodiment of the present invention, as shown in fig. 2, 8 bragg fiber gratings with different central wavelengths are selected and arranged on 8 identification side lines parallel to the axis on the surface of an elastic body respectively by using a wavelength division multiplexing technology to form a three-dimensional coordinate sensing probe, and then the three-dimensional coordinate sensing probe is arranged on a measuring drill cylinder modified from a common drill cylinder. The cylindrical elastic body 2 and the mass block 3 can be fixed by a fixed seat 4 at a proper position of the measuring drill cylinder 1. 8 Bragg fiber gratings (5-12) with different central wavelengths are arranged on 8 identification edge lines (b is 1,2, …, 8) of which the surfaces are parallel to the axis and correspond to 8 angles
The pipeline path three-dimensional detection and reconstruction system based on the Bragg fiber grating comprises a broadband light source, a first optical splitter, a second optical splitter and a three-dimensional coordinate sensing probe. The three-dimensional coordinate sensing probe is based on the pipeline path of the Bragg fiber grating.
The broadband light source is connected with one branching port of the first optical branching device; the combining port of the first optical splitter is connected with the combining port of the second optical splitter through a conducting optical fiber; and a plurality of branch ports of the second optical splitter are connected with the three-dimensional coordinate sensing probe.
The system also comprises a wavelength demodulator and a computer, wherein the input end of the wavelength demodulator is connected with the other branching port of the first optical branching device; the output end of the wavelength demodulator is connected with the computer through a data line.
The spectral width of the broadband light source covers all the characteristic wavelengths of the fiber grating.
As shown in fig. 5, the reconstruction method of the system specifically includes the following steps:
s1, enabling light emitted by the broadband light source to pass through the first optical splitter, the conducting optical fiber and the second optical splitter and to be incident on the three-dimensional coordinate sensing probe;
s2, after the incident light is reflected by the three-dimensional coordinate sensing probe, the reflected light is transmitted to a wavelength demodulator through a first optical splitter;
s3, when the axis of the elastic body deviates from the gravity direction, the fiber bragg gratings are caused to generate wavelength drift, and the wavelength demodulator demodulates the central wavelengths of the fiber bragg gratings in the three-dimensional coordinate sensing probe and transmits the central wavelengths to the computer;
s4, the computer calculates the wavelength drift according to the demodulated central wavelength, and then calculates the three-dimensional position coordinates of the drill barrel including the azimuth angle and the inclination angle deviating from the gravity direction according to the relationship between the wavelength drift and the fiber bragg grating strain and curvature.
Taking the three-dimensional coordinate sensing probe of fig. 2 as an example, i.e. a probe using 8 fiber gratings, as shown in fig. 3, a preferred embodiment of the present invention, a pipeline path three-dimensional detection and reconstruction system based on bragg fiber gratings, includes a
The light emitted from the
The length of the measuring drill cylinder provided with the three-dimensional coordinate sensing probe is recorded as ls. When the measuring drill barrel penetrates into the ground from top to bottom section by section, the path of the measuring drill barrel can be represented by a series of section lines, and the turning point of the section line is represented by a series of coordinates (x) of the lower end point of the drill barreli,yi,zi) Determine where i is 0,1,2, … Ns. Where i is 0 as the starting point, (x)0,y0,z0) Is the ground start coordinate.
When the axis of the elastomer deviates from the gravity direction, the elastomer bends. Causing the 8 fiber gratings on the elastomer to undergo a wavelength shift, whose wavelength shift Δ λ is related to the strain and the radius of curvature R at the location of the gratings:
where r is the radius of the cylindrical elastomer. The following table can then be prepared to record the wavelength drift data:
from this, the cosine function shown in FIG. 4 can be fitted
Wherein the amplitude gives the formula of the inclination angle theta
Δλmax＝·sinθ (3)
Depending here on the dimensions and material properties of the cylindrical elastomer and mass. The angle corresponding to the maximum value corresponds to the phase angle of the measuring drill barrelCan be divided into two zero positions
the position coordinates of the lower end point of the measuring drill rod can be calculated by the length of the measuring drill rod, and the inclination angle and the phase angle.
In conclusion, the invention has the advantages that: (1) the fiber grating pipeline path three-dimensional detection reconstruction method completely adopts optical signals in a sensing and transmission area, is electrically insulated, and has the characteristics of intrinsic safety, explosion prevention, lightning protection, electromagnetic interference resistance and the like; (2) the fiber grating sensing probe has small size and light weight, and is easy to install and use in the drill cylinder; (3) the oil well has a distance of several hundred meters to 2 kilometers generally, and the anti-interference long-distance transmission can be realized by adopting the fiber grating sensing system; (4) by adopting the wavelength division multiplexing technology, the detection and reconstruction of the oil well pipeline path can be realized by connecting 8, 16 or even 32 Bragg fiber gratings with different wavelengths in series on one optical fiber.
It will be understood that modifications and variations can be made by persons skilled in the art in light of the above teachings and all such modifications and variations are intended to be included within the scope of the invention as defined in the appended claims.
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