CN103383241B - A kind of frozen soil district oil and gas pipes monitoring method and system - Google Patents

Abstract

The present invention is a kind of frozen soil district oil and gas pipes monitoring method and system. Its flow process is: the temperature around pipeline, moisture and pipe displacement body are monitored by the fiber grating displacement sensor group of sets of temperature sensors, water content sensor group and composition respectively; The signal that monitoring obtains passes to photoswitch (13) through optical cable (12), lower computer (15) is reached through (FBG) demodulator (14) demodulation, lower computer (15) calls self-editing program, control photoswitch (13) and (FBG) demodulator (14), data are also carried out pre-treatment by image data; Pretreated data transfer to low-orbit satellite (17) by satellite communication module (16), low-orbit satellite (17) receives data and is forwarded to satellite communication module (18), the transfer received is carried out treatment and analysis to upper computer (19) by satellite communication module (18), judge the safe state of pipeline, carry out disaster forecast. Precision height of the present invention, the high and low cost of stability.

Description

A kind of frozen soil district oil and gas pipes monitoring method and system

Technical field

The present invention is a kind of frozen soil district oil and gas pipes monitoring method based on fiber grating sensing technology and system, it relates to the measurement of length, the measurement of temperature, other class do not comprise measurement, general Controlling System and tubing system technical field.

Background technology

Frozen soil is a kind of special great soil group, and temperature is negative temperature or zero temperature, and the soil containing ice, it is called frozen soil. By the length of the frozen state hold-time of soil, frozen soil generally can be divided into again frozen soil (a few hours to half month), frozen soil in season (half month to the several months) and ever frost (more than 2 years) in short-term. China's frozen soil is grown very much, and ever frost area is about 2,110,000 square kilometres, accounts for the 23% of China's territory total area, accounts for the 3rd in the world, is mainly distributed in Qinghai-Tibet Platean, western high mountain and northeast Xing'anling mountains; Seasonal frozen soil area is about 5,140,000 square kilometres, accounts for the 53.5% of territory total area. Wherein, middle degree of depth frozen soil in season (> 1m) accounts for the 1/3 of area, is mainly distributed in the ground such as three provinces in the northeast of China, the Inner Mongol, Gansu, Ningxia, the north, Xinjiang, Qinghai and Chuan Xi.

Developed country's oil pipeline construction has more than 100 year history, and a lot of frozen soil area is contained huge hydrocarbon resources, and correspondingly oil and gas pipes engineering design and construction becomes the up-to-date challenge of these area petroleum industries. From the sixties in 20th century, large diameter pipeline starts leading northern North america and Permafrost Area, siberian oil-gas field transports market.During World War II, gram exert (Canol) pipeline and transport crude oil this city of Alaska State Fairbank (Fairbanks) to the U.S. from Canada's Luo Man well; The oil pipe that caliber in 1956 is 203mm is built successfully from Hai Yinsi city, Alaska State (Haines) to Fei Bankesi city; The seventies in 20th century is early stage, and USSR (Union of Soviet Socialist Republics) ever frost district has oil pipeline; 1977, long 1280km, diameter are the natural warm water port Wa Erdisi (Valdez) that the crude oil in north slope low temperature ever frost district, Alaska State of the U.S. is transported to south, Alaska by the oil pipeline of 1220mm continuously, then oil tanker by crude oil transportation to California. 20th century the mid-80, economize from Canada's Luo Man well to Canada's Ahlport (Alberta) our horse (Zama) lake northern, long 869km, bore 30.5cm envrionment temperature pipeline complete to lay on time, Luo Man well conduit is the oil pipeline that Canada's ever frost district Article 1 is buried underground completely. These pipelines are during runing, and the threat being all subject to frozen soil district frozen swell and melt settlement disaster even destroys. Wherein, gram exerting (Canol) pipeline after starting to run first 9 months, pipeline about has 700x10 along the line⁴L crude oil leakage. A 12700m on Mackenzie riverbank³Storage tank farm break, major part oil storage flows in river. After Japan surrenders in 1945, this pipeline is removed soon; Luo Man well conduit is along the line by way of discontinuous ever frost, construction and operation meet frost-heaving and thawing problem, by reaching the monitoring of 17 years, find that pipeline ever frost along the line continues to melt causes the thawing degree of depth to reach 3-5m (lacustrine facies deposition) or 5-7m (coarse particles mineral soil) with sedimentation, and significant land subsidence.

The Article 1 long-distance oil & gas pipeline that China builds in Permafrost Area, i.e. Golmud-Lhasa oil pipeline (being called for short lattice bracing wire), lattice bracing wire was constructed in 1972 by the Chinese People's Liberation Army, within 1977, substantially build up, reach 1076km, caliber 159mm, thickness of pipe 6mm, investment 2.3x108 is first. Lattice bracing wire engineering is built and is safeguarded very difficult, completely 108, spanning of river, and road crossing 123 place, more than 900 kilometer of pipeline is at more than height above sea level 4000m (highest point height above sea level 5200m), and 560km is positioned at ever frost district, and freezing period reaches 8 months. Since lattice bracing wire ran from 1977, frost heave, melt heavy problem and caused repeatedly " dew pipe " phenomenon.

Sino-Russian crude oil pipeline, North gets boundary line, Sino-Russian Heilungkiang, Mo River initial station, reaches station, grand celebration end in the south, and total length more than 960 kilometer, by way of counties and districts of 12, two city of province five, passes through 440 kilometers of virgin forests, 11 big-and-middle-sized rivers, 5 wilderness areas. High south, pipeline physical features along the line north is low, and northern topographic relief is relatively big, is low mountain, Daxing'an Mountainrange, hills and river valley landforms along the line, and south is song-Nen plain, and landform is smooth open; Mo River-Jagdaqi section about 460km is mountain area, forest zone, ever frost district, and ever frost total length is about 314km, wherein lacks ice, many ice ever frost 209km, full ice, rich ice ever frost 62km, frozen soil marsh 43km. Pipeline faces serious frozen swell and melt settlement disaster threat.

For the frozen swell and melt settlement problem that pipeline faces, domestic and international unit of operation takes positive counter-measure. After Luo Man well conduit is gone into operation for 1985, the daily monitoring plan of pipeline is being implemented as the important component part of project operation always, except weekly aircraft aerial surveillance, also a large amount of measuring instruments is installed to record service data along the line at pipeline, and in annual September, carry out once on-the-spot exploration when namely pipe sedimentation is maximum to complete the work such as pipeline field investigation along the line, the record of instrument data and the on-the-spot assessment in location, landslide.After 1989, Luo Man well conduit adopts in-pipeline detector to carry out annual interior detection, the heavy influence degree to pipeline is melted, along with continuous accumulation and the expansion of detection data, for the assessment of pipe technology performance provides good basis to assess unstable soil body motion and otherness. Normanwells pipeline is the oil and gas pipes that Article 1 is embedded in northern ever frost district of Canada, it is in charge of by Jia Na Enbridge company and is runed, under the requirement of various regulations regulation, establish one and planned Monitoring systems careful, strong operability, melt the content of seven aspects such as heavy monitoring, pipeline detection, warpage arch detection, wrinkle detection, slope test, the detection of wood chip layer status and temperature monitoring comprising frozen soil. Gubbs criterion is also by regularly patrolling the change of the monitoring frozen soil such as line, setting pressure, temperature sensor.

Although pipeline unit of operation takes the frozen swell and melt settlement disaster in positive measure reply frozen soil district both at home and abroad, but owing to the formation mechenism of frozen swell and melt settlement disaster is very complicated, and the frozen soil characteristic of different areas is different, at present both at home and abroad and there are no the Monitoring techniques of maturation, it is possible to monitoring frozen swell and melt settlement disaster is on the impact of pipeline.

Summary of the invention

It is an object of the invention to invent monitoring method and the system of the frozen soil district oil and gas pipes based on fiber grating sensing technology of a kind of high precision, high stability, low cost.

The present invention proposes the monitoring method of a kind of frozen soil district oil and gas pipes based on fiber grating sensing technology and system. System adopts fiber grating sensing technology, and the oil and gas pipes under frozen soil and impact thereof is carried out combined monitoring. And construct Monitoring systems, it is achieved that real-time automatic collecting, the remote transmission of data and automatically analyze.

The frozen soil district oil and gas pipes monitoring method based on fiber grating sensing technology that the present invention proposes, its monitoring content comprises three parts: the monitoring of pipe displacement body, the monitoring of frozen soil district temperature monitoring, frozen soil district water content. Wherein, the monitoring of pipe displacement body adopts fiber grating displacement sensor real time on-line monitoring, and frozen soil district temperature monitoring adopts fiber-optical grating temperature sensor real time on-line monitoring, and water content monitoring in frozen soil district adopts fiber grating water content sensor real time on-line monitoring.

Based on fiber grating sensing technology frozen soil district oil and gas pipes monitoring method monitoring method principle flow chart as shown in Figure 1, monitoring method is as shown in Figure 2. in frozen soil district 1 oil and gas pipes a2 surface and around multiple fiber-optical grating temperature sensor a3 is installed, fiber-optical grating temperature sensor b4, the sets of temperature sensors that fiber-optical grating temperature sensor c5 forms, multiple fiber grating water content sensor a6 is installed around oil and gas pipes a2, fiber grating water content sensor b7, fiber grating water content sensor c8, the water content sensor group that fiber grating water content sensor d9 forms, in oil and gas pipes 2 side, multiple fiber grating displacement sensor a10 is installed, fiber grating displacement sensor b11, all the sensors series connection welding, then guide in monitoring station by optical cable 12, optical cable 12 is connected with photoswitch 13, photoswitch 13 is connected with fiber Bragg grating (FBG) demodulator 14, (FBG) demodulator 14 is connected with lower computer 15, the pretreated data of lower computer 15 transfer to low-orbit satellite 17 by satellite communication module 16, low-orbit satellite 17 forwards the data to satellite communication module 18 after receiving data, the transfer received is carried out treatment and analysis to upper computer 19 by satellite communication module 18, thus realize the safety to frozen soil district oil and gas pipes and monitor.

The monitoring flow process of frozen soil district oil and gas pipes: by multiple fiber-optical grating temperature sensor a3, fiber-optical grating temperature sensor b4, the sets of temperature sensors that fiber-optical grating temperature sensor c5 forms, multiple fiber grating water content sensor a6, fiber grating water content sensor b7, fiber grating water content sensor c8, the water content sensor group that fiber grating water content sensor d9 forms and multiple fiber grating displacement sensor a10, fiber grating displacement sensor b11 is respectively to the temperature around pipeline, moisture and pipe displacement body are monitored, the signal that this monitoring obtains is gathered and pre-treatment by lower computer 15, pretreated data are through teletransmission and reception, to upper computer 19, treatment and analysis is carried out by upper computer 19, judge the safe state of frozen soil district pipeline, carry out pipe temperature field, frozen soil district Dynamic Announce, frozen soil district pipe displacement body Dynamic Announce, Pipeline Water branch, frozen soil district Dynamic Announce, the frozen swell and melt settlement disaster forecast of frozen soil district, the safe early warning of oil and gas pipes.

Multiple fiber-optical grating temperature sensor a3, fiber-optical grating temperature sensor b4, the sets of temperature sensors that fiber-optical grating temperature sensor c5 forms, multiple fiber grating water content sensor a6, fiber grating water content sensor b7, fiber grating water content sensor c8, the water content sensor group that fiber grating water content sensor d9 forms and multiple fiber grating displacement sensor a10, fiber grating displacement sensor b11 is respectively to the temperature around pipeline, moisture and pipe displacement body are monitored, this signal of obtaining of monitoring passes to photoswitch 13 through optical cable 12, reaches lower computer 15 through (FBG) demodulator 14 demodulation, and lower computer 15 calls self-editing program, control photoswitch 13 and (FBG) demodulator 14, it is achieved data are also carried out pre-treatment by the collection of data, pretreated data transfer to low-orbit satellite 17 by satellite communication module 16, low-orbit satellite 17 forwards the data to satellite communication module 18 after receiving data, the transfer received is carried out treatment and analysis to upper computer 19 by satellite communication module 18, judges the safe state of frozen soil district pipeline.

The process of data completes primarily of software, and software flow (as shown in Figure 3) is: after starting, lower computer data gathering; Photoswitch conducting; Fiber Bragg grating (FBG) demodulator image data; Lower computer data prediction; Satellite communications; Does upper computer judge that whether data complete? if not, then return lower computer data prediction, if then processing and judging that data exceed valve value? if exceeding, then report to the police.

Lower computer data prediction mainly by the optical wavelength data of fiber Bragg grating (FBG) demodulator collection according to being converted into temperature, moisture and displacement data, upper computer is after receiving the data, first data are classified, draw out pipeline surrounding temperature and the trend map of water content and piping displacement thereof, and three monitoring data merge the most at last, judge the steady state in frozen soil district and the safety case of pipeline.

Wherein:

Piping displacement monitoring method: piping displacement monitoring method adopts fiber grating displacement sensor, and its structure is as shown in Figure 4. Near pipeline b20, installing fixed link 21, fixed link 21 is deep into permafrost certain depth, can not be moved to ensure. Installing slide block 22 on fixed link 21, slide block 22 is with thin expansion link 23 mode of connection for welding, and thin expansion link 23 stretches in thick expansion link 24, fills butter, to ensure that thin expansion link 23 can move flexibly in thick expansion link 24.Thick expansion link 24 and pipeline b20 are linked together by pipe clamp 25, thick expansion link 24 with pipe clamp 25 mode of connection for welding. Like this, when pipeline b20 is moved, displacement can be passed to thick expansion link 24 by pipe clamp 25, displacement is passed to thin expansion link 23 by thick expansion link 24, displacement is passed to slide block 22 by thin expansion link 23, slide block 22 is connected with fiber grating displacement sensor c26, and wherein fiber grating displacement sensor c26 is large displacement sensor, needs to impose certain pretension when mounted. Fiber grating displacement sensor c26 is connected with data collector by cable junction box 27, it is achieved the monitoring of pipe displacement body.

Piping displacement monitoring method is: pipe displacement body is monitored by fiber grating displacement sensor a10, fiber grating displacement sensor b11; The signal that this monitoring obtains is gathered and pre-treatment by lower computer 15, pretreated data are through teletransmission and reception, to upper computer 19, treatment and analysis is carried out by upper computer 19, judge the safe state of frozen soil district pipeline, carry out pipe temperature field, frozen soil district Dynamic Announce, frozen soil district pipe displacement body Dynamic Announce, Pipeline Water branch, frozen soil district Dynamic Announce; The frozen swell and melt settlement disaster forecast of frozen soil district; The safe early warning of oil and gas pipes.

Permafrost hazards causes pipeline to be subjected to displacement, and then the stress causing pipeline changes, the mainly change of axial stress, therefore, judge pipeline whether safety, only the axis stress of pipeline and pipe body yielding stress need to be contrasted, if exceeding yielding stress, then report to the police. The calculation formula between displacement y and conduit axis stress �� of pipeline is as follows:

When calculating, pipeline is regarded the beam of the semi-infinite space as, according to the STRESS VARIATION of ground beam theory qualitative analysis pipeline.

According to theory of mechanics of materials, piping displacement y curve is:

$y=-\frac{2\mathrm{\Δ}}{l^3}{x}^3+\frac{3\mathrm{\Δ}}{l^2}{x}^2---\left(1\right)$

And the calculation formula of moment M:

$M=-{\mathrm{EI}}_z\frac{d^{2}y}{{\mathrm{dx}}^2}---\left(2\right)$

Formula (1) is substituted into formula (2) obtain:

$M={\mathrm{EI}}_z(\frac{6\mathrm{\Δ}}{l^2}-\frac{12\mathrm{\Δ}}{l^3}x)---\left(3\right)$

I_zFor beam section moment of inertia, I_zCalculation formula be:

$I_z=\mathrm{\π}{R}^3\mathrm{\δ}+\frac{3}{2}\mathrm{\π}{R}^2{\mathrm{\δ}}^2+\mathrm{\π}{\mathrm{R\δ}}^3+\frac{1}{4}\mathrm{\π}{\mathrm{\δ}}^4---\left(4\right)$

The then axis stress �� of pipeline section:

$\mathrm{\σ}=\frac{\mathrm{My}}{I_z}---\left(5\right)$

In formula: E is tubing Young's modulus; R is internal diameter of the pipeline, and �� is pipeline wall thickness.

As mentioned above, it is necessary, the displacement y occurred according to pipeline, calculate the axis stress �� of pipeline, �� and pipeline yielding stress are contrasted, judges the safe state of pipeline.

Frozen soil district temperature monitoring method: monitored by temperature field, can grasp freeze thawing circle and change state thereof around pipeline, is the important evidence judging whether pipeline exists freeze thawing harm and potentially dangerous. What frozen soil district temperature monitoring adopted is fiber-optical grating temperature sensor, and its structure is as shown in Figure 5. At pipeline c28 up and down, fiber-optical grating temperature sensor group a29, fiber-optical grating temperature sensor group b30, fiber-optical grating temperature sensor group c31, fiber-optical grating temperature sensor group d32 are installed respectively. Fiber-optical grating temperature sensor group a29 is made up of some fiber-optical grating temperature sensor d33, and the quantity of fiber-optical grating temperature sensor d33 and interval can be arranged according to demand. Connected by single core armouring optical cable 34 between fiber-optical grating temperature sensor group b30 and fiber-optical grating temperature sensor group d32. Fiber-optical grating temperature sensor group a29, fiber-optical grating temperature sensor group b30, fiber-optical grating temperature sensor group c31, fiber-optical grating temperature sensor group d32 are connected with data collector by cable junction box 35, it is achieved the monitoring of pipeline surrounding temperature.

Frozen soil district temperature monitoring method is: the temperature around pipeline is monitored by the sets of temperature sensors being made up of fiber-optical grating temperature sensor a3, fiber-optical grating temperature sensor b4, fiber-optical grating temperature sensor c5;The signal that this monitoring obtains is gathered and pre-treatment by lower computer 15, pretreated data are through teletransmission and reception, to upper computer 19, treatment and analysis is carried out by upper computer 19, judge the safe state of frozen soil district pipeline, carry out pipe temperature field, frozen soil district Dynamic Announce, frozen soil district pipe displacement body Dynamic Announce, Pipeline Water branch, frozen soil district Dynamic Announce; The frozen swell and melt settlement disaster forecast of frozen soil district; The safe early warning of oil and gas pipes.

The temperature of frozen soil layer is decided by the comprehensive action of nature palegeology factor, and thermal exchange condition between its reflection earth's crust and atmospheric sphere is one of important feature of frozen soil layer. We adopt the year-round average temperature bottom soil temperature year change layer represent and contrast frozen soil layer temperature. First the temperature value that each position is measured is depicted as curve according to the degree of depth, on temperature curve, order is got a little, each numerical value (degree of depth and temperature) put is substituted into formula (6), and till equation two ends are equal, the temperature thus drawn is year-round average temperature T_C, the depth value drawn adds that the Seasonal analysis degree of depth is the year varying depth D of soil temperature.

$\ln \frac{t_{\mathrm{cp}}}{0.1}=Z\sqrt{\frac{\mathrm{\π}}{\mathrm{KT}}}---\left(6\right)$

In formula: t_cpFor mean annual cost (DEG C); Z is year varying depth (m) of soil temperature; K is soil layer thermal diffusivity (cm2 s-1); T is annual cycle (s).

Calculate soil layer year varying depth D according to radical (6), just can know that pipeline is to the range of influence of frozen soils temperature field, and then calculated under this kind of impact that pipeline is contingent melts heavy situation further by finite element method.

Frozen soil district water content monitoring method: pipeline surrounding soil water ratio is one of key parameter determining soil physical factors, directly has influence on the frost-heaving and thawing feature of soil; Due to the water migration effect of soil in frozen-thaw process, pipeline surrounding soil water ratio is made to be in change procedure; Monitored by moisture field, especially for the long term monitoring of the total water-cut variation freezing soil, it is determined that water-cut variation state and trend, comprehensively analyze for pipe and soil interaction and the judgement of pipeline potential risk. The water content monitoring of frozen soil district adopts fiber grating water content sensor, and its structure is as shown in Figure 6. Fiber grating water content sensor group 37 is installed in the left side of pipeline d36, fiber grating water content sensor group 38 is installed on the right side of pipeline d36, fiber grating water content sensor group 39 is installed in the downside of pipeline d36. Water content sensor group 37 is made up of some fiber grating water content sensors 40, and the quantity of fiber grating water content sensor 40 and interval can be arranged according to demand. Connected by single core armouring optical cable 41 between water content sensor group 38 and water content sensor group 39. Sets of temperature sensors 37,38,39 is connected with data collector by cable junction box 42, it is achieved the monitoring of pipeline surrounding aqueous amount.

Frozen soil district water content monitoring method is: the moisture around pipeline is monitored by the water content sensor group being made up of fiber grating water content sensor b7, fiber grating water content sensor c8, fiber grating water content sensor d9; The signal that this monitoring obtains is gathered and pre-treatment by lower computer 15, pretreated data are through teletransmission and reception, to upper computer 19, treatment and analysis is carried out by upper computer 19, judge the safe state of frozen soil district pipeline, carry out pipe temperature field, frozen soil district Dynamic Announce, frozen soil district pipe displacement body Dynamic Announce, Pipeline Water branch, frozen soil district Dynamic Announce; The frozen swell and melt settlement disaster forecast of frozen soil district;The safe early warning of oil and gas pipes.

When frost heave disaster occurs, the water content in frozen soil changes. And the soil body of not all can produce frost heave, only frost heave could be produced when foundation soil water content exceedes certain boundary value. Usually this Atterberg limits is called initial frost heaving amount W₀, the plastic limit water content of soil is W_p, the natural aqueous value of soil that water content sensor is measured is W, then, when W meets following formula, strong frost heave will occur the soil body.

W_p+ 5 < W��W_p+15(7)

In formula: W_pFor soil plastic limit water content, obtain by experiment.

By formula in the observed value W substitution of water content sensor, when the condition is satisfied, system becomes and can automatically report to the police.

This frozen soil district oil and gas pipes monitoring method system for use in carrying:

Devise frozen soil district oil and gas pipes Monitoring systems according to the method described above. As shown in Figure 7, this system is divided into on-site data gathering transmission subsystem and data analysis display subsystem, specifically comprises fiber grating displacement sensor group, fiber-optical grating temperature sensor group, fiber grating water content sensor group, field monitoring station, remote monitoring center.

The overall formation of frozen soil district oil and gas pipes Monitoring systems is as shown in Figure 2. in frozen soil district 1 oil and gas pipes 2 surface and around multiple fiber-optical grating temperature sensor a3 is installed, fiber-optical grating temperature sensor b4, the sets of temperature sensors that fiber-optical grating temperature sensor c5 forms, multiple fiber grating water content sensor a6 is installed around oil and gas pipes 2, fiber grating water content sensor b7, fiber grating water content sensor c8, the water content sensor group that fiber grating water content sensor d9 forms, in oil and gas pipes 2 side, multiple fiber grating displacement sensor a10 is installed, fiber grating displacement sensor b11, all the sensors series connection welding, then guide in monitoring station by optical cable 12, optical cable 12 is connected with photoswitch 13, photoswitch 13 is connected with fiber Bragg grating (FBG) demodulator 14, fiber Bragg grating (FBG) demodulator 14 is connected with lower computer 15, the pretreated data of lower computer 15 transfer to low-orbit satellite 17 by satellite communication module 16, low-orbit satellite 17 forwards the data to satellite communication module 18 after receiving data, the transfer received is carried out treatment and analysis to upper computer 19 by satellite communication module 18, thus realize the safety to frozen soil district oil and gas pipes and monitor.

Multiple fiber-optical grating temperature sensor a3, fiber-optical grating temperature sensor b4, fiber-optical grating temperature sensor c5, fiber grating water content sensor a6, fiber grating water content sensor b7, fiber grating water content sensor c8, fiber grating water content sensor d9, fiber grating displacement sensor a10, fiber grating displacement sensor b11 is respectively by the temperature around pipeline, moisture and pipe displacement body signal pass to photoswitch 13 through optical cable 12, lower computer 15 is reached through fiber Bragg grating (FBG) demodulator 14 demodulation, lower computer 15 calls self-editing program, control photoswitch 13 and fiber Bragg grating (FBG) demodulator 14, realize the collection of data and data are carried out pre-treatment, pretreated data transfer to low-orbit satellite 17 by satellite communication module 16, low-orbit satellite 17 forwards the data to satellite communication module 18 after receiving data, the transfer received is carried out treatment and analysis to upper computer 19 by satellite communication module 18, judges the safe state of frozen soil district pipeline. the process of data completes primarily of software, and software flow is as shown in Figure 3. lower computer data prediction mainly by the optical wavelength data of fiber Bragg grating (FBG) demodulator collection according to being converted into temperature, moisture and displacement data, upper computer is after receiving the data, first data are classified, draw out pipeline surrounding temperature and the trend map of water content and piping displacement thereof, and three monitoring data merge the most at last, judge the steady state in frozen soil district and the safety case of pipeline.

As shown in Figure 7, it is divided into on-site data gathering transmission subsystem and data analysis display subsystem to the functional block diagram of frozen soil district oil and gas pipes Monitoring systems. Corresponding to the monitoring method of frozen soil district oil and gas pipes, system comprises again displacement monitor, device for detecting temperature and water content monitoring device three part. The composition of on-site data gathering transmission subsystem is: the output of fiber grating displacement sensor, fiber-optical grating temperature sensor and fiber grating water content sensor connects the input of photoswitch, the output of photoswitch connects the input of fiber Bragg grating (FBG) demodulator, fiber Bragg grating (FBG) demodulator exports the input connecing lower computer, and lower computer exports and connects satellite communication module. On-site data gathering transmission subsystem is by low-orbit satellite and data analysis display subsystem communication. The composition of data analysis display subsystem is: satellite communication module exports the input connecing upper computer, and upper computer exports frozen soil district temperature field Dynamic Announce, frozen soil district piping displacement Dynamic Announce, moisture field, frozen soil district Dynamic Announce.

The electric principle of this system is as shown in Figure 8, fiber-optical grating temperature sensor group, the FC joint of fiber grating water content sensor group and fiber grating displacement sensor group inputs port 1 with the FC of photoswitch respectively, FC inputs port 2, FC inputs port 3 and connects, the R232 port of photoswitch connects the R232 port 1 of lower computer, the FC that the FC output port of photoswitch connects fiber Bragg grating (FBG) demodulator inputs port, the LAN port of fiber Bragg grating (FBG) demodulator connects the LAN port of lower computer, the VGA of lower computer is connected with the VGA of indicating meter, the R232 port 2 of lower computer connects the R232 port of satellite communication module, satellite communication module transfers data to low-orbit satellite, low-orbit satellite forwards the data to another satellite communication module in real time, this satellite communication module will receive data by R232 port transmission to the R232 port of upper computer, upper computer exports indicating meter to after Data Analysis Services to by VGA port.

The fiber-optic grating sensor signal of three types through photoswitch 13 one by one conducting transfer to fiber Bragg grating (FBG) demodulator 14, the centre wavelength that fiber Bragg grating (FBG) demodulator 14 demodulates each fiber-optic grating sensor transfers to lower computer 15, and the cycle of photoswitch 13 conducting signal is controlled by lower computer 15. Data are carried out pre-treatment by lower computer 15, and the data after process are defeated by satellite communication module 16, satellite communication module 16 transfers data to low-orbit satellite 17, low-orbit satellite 17 forwards the data to satellite communication module 18 in real time, satellite communication module 18 will receive transfer to upper computer, data are carried out analyzing and processing by self-programmed software by upper computer, show by indicating meter.

Fiber-optical grating temperature sensor, fiber grating displacement sensor and fiber grating water content sensor are develops sensor voluntarily. Fiber-optical grating temperature sensor adopts the structure of double-layer pipe, not only increases the sensitivity of sensor, and serves provide protection. Fiber grating displacement sensor adopts temp. compensation type, eliminates temperature to the impact of measuring result, it is to increase the measuring accuracy of displacement sensor. Fiber grating water content sensor utilizes soil water suction and soil moisture content to have the principle of corresponding relation to develop, fiber grating water content sensor is made up of vitrified-clay pipe and vacuum box, vitrified-clay pipe is sensor, after soil put into by vitrified-clay pipe, the water-content of soil can cause the change of vacuum box pressure, and the change of vacuum box pressure can cause the change of optic fiber grating wavelength, and then the water-content of soil can be gone out according to the change calculations of optic fiber grating wavelength.

Except foregoing circuit part, the construction process of the fiber-optical grating temperature sensor group of frozen soil district oil and gas pipes Monitoring systems, fiber grating water content sensor group and fiber grating displacement sensor group is:

The formation of pipeline fiber grating displacement sensor group is as shown in Figure 4: near pipeline b20, installs fixed link 21, and fixed link 21 is deep into permafrost certain depth, can not be moved to ensure.Installing slide block 22 on fixed link 21, slide block 22 is with thin expansion link 23 mode of connection for welding, and thin expansion link 23 stretches in thick expansion link 24, fills butter, to ensure that thin expansion link 23 can move flexibly in thick expansion link 24. Thick expansion link 24 and pipeline b20 are linked together by pipe clamp 25, thick expansion link 24 with pipe clamp 25 mode of connection for welding. Like this, when pipeline b20 is moved, displacement can be passed to thick expansion link 24 by pipe clamp 25, displacement is passed to thin expansion link 23 by thick expansion link 24, displacement is passed to slide block 22 by thin expansion link 23, slide block 22 is connected with fiber grating displacement sensor 26, and wherein fiber grating displacement sensor 26 is large displacement sensor, needs to impose certain pretension when mounted. Fiber grating displacement sensor 26 is connected with data collector by cable junction box 27, it is achieved the monitoring of pipe displacement body.

The formation of frozen soil district fiber-optical grating temperature sensor group is as shown in Figure 5: at pipeline c28 up and down, installs fiber-optical grating temperature sensor group a29, fiber-optical grating temperature sensor group b30, fiber-optical grating temperature sensor group c31, fiber-optical grating temperature sensor group d32 respectively. Sets of temperature sensors 29 is made up of some fiber-optical grating temperature sensors 33, and the quantity of fiber-optical grating temperature sensor 33 and interval can be arranged according to demand. Connected by single core armouring optical cable 34 between sets of temperature sensors 30 and sets of temperature sensors 32. Fiber-optical grating temperature sensor group a29, fiber-optical grating temperature sensor group b30, fiber-optical grating temperature sensor group c31, fiber-optical grating temperature sensor group d32 are connected with data collector by cable junction box 35, it is achieved the monitoring of pipeline surrounding temperature.

The formation of frozen soil district fiber grating water content sensor group is as shown in Figure 6: install fiber grating water content sensor group 37 in the left side of pipeline d36, fiber grating water content sensor group 38 is installed on the right side of pipeline d36, fiber grating water content sensor group 39 is installed in the downside of pipeline d36. Water content sensor group 37 is made up of some fiber grating water content sensors 40, and the quantity of fiber grating water content sensor 40 and interval can be arranged according to demand. Connected by single core armouring optical cable 41 between water content sensor group 38 and water content sensor group 39. Fiber grating water content sensor group a37, fiber grating water content sensor group b38, fiber grating water content sensor group c39 are connected with data collector by cable junction box 42, it is achieved the monitoring of pipeline surrounding aqueous amount.

The advantage of present method and system shows:

(1) propose to be carried out by the lower oil and gas pipes in frozen soil district and impact thereof the method for combined monitoring, disclose frozen soil effect lower tube body stress characteristic and the feature of Guan Tiyu frozen soil interaction; The safe early warning of the lower oil and gas pipes of frozen soil impact is carried out with multi objective;

(2) fiber grating sensing technology being applied to frozen soil district Monitoring Pinpelines, it is with the obvious advantage that this technology is anti-interference, corrosion-resistant, be easy to networking etc.; This technology is easy to realize automatic real time on-line monitoring, and cost is lower;

(3) piping displacement monitoring, feature according to frozen soil district, pipeline place, installs fixed link in pipeline side, adopts the mode of connection of expansion link pipeline and fixed link to be linked together, fixed link is installed fiber grating displacement sensor, the misalignment of monitoring pipeline; By excavation pipeline, this kind of monitoring method avoids distinguishes whether pipeline is subjected to displacement, the selection carrying out protection works opportunitys for frozen soil district oil and gas pipes provides effective foundation, decrease the blindness of protection works and saved conduit running cost, also ensure that the operating safety of pipeline simultaneously, decrease construction risk during excavation checking;

(4) frozen soil district temperature monitoring, adopting fiber-optical grating temperature sensor monitoring frozen soil district temperature, owing to fiber grating sensing technology has the advantage of wavelength-division multiplex, an optical fiber can be connected multiple fiber-optical grating temperature sensor, what avoid complexity walks line, also saves cost simultaneously.

Accompanying drawing explanation

Tu1Cai frozen soil district oil and gas pipes monitoring method principle flow chart

Fig. 2 frozen soil district oil and gas pipes monitoring method figure

Fig. 3 software flow figure

Fig. 4 piping displacement monitoring device figure

Fig. 5 frozen soil district device for detecting temperature figure

Fig. 6 frozen soil district water content monitoring device figure

Fig. 7 frozen soil district oil and gas pipes Fundamentals of Supervisory Systems figure

Fig. 8 frozen soil district oil and gas pipes Monitoring systems electrical schematic diagram

Wherein 1-frozen soil district 2-pipeline a

3-fiber-optical grating temperature sensor a4-fiber-optical grating temperature sensor b

5-fiber-optical grating temperature sensor c6-fiber grating water content sensor a

7-fiber grating water content sensor b8-fiber grating water content sensor c

9-fiber grating water content sensor d10-fiber grating displacement sensor a

11-fiber grating displacement sensor b12-optical cable

13-photoswitch 14-fiber Bragg grating (FBG) demodulator

15-lower computer 16-satellite communication module a

17-low-orbit satellite 18-satellite communication module b

19-upper computer 20-pipeline b

21-fixed link 22-slide block

The 23-thin expansion link thick expansion link of 24-

25-pipe clamp 26-fiber grating displacement sensor c

27-cable junction box a28-pipeline c

29-fiber-optical grating temperature sensor group a30-fiber-optical grating temperature sensor group b

31-fiber-optical grating temperature sensor group c32-fiber-optical grating temperature sensor group d

33-fiber-optical grating temperature sensor d34-mono-core armouring optical cable a

35-cable junction box b36-pipeline d

37-fiber grating water content sensor group a38-fiber grating water content sensor group b

39-fiber grating water content sensor group c40-fiber grating water content sensor e

41-mono-core armouring optical cable b42-cable junction box c

Embodiment

Embodiment. this example is a kind of test method and system, and has tested in the frozen soil district that seasonal thickness of frozen earth layer 2m, frozen ground types are the full ice of rich ice, wherein buried depth of pipeline 2m, and pipe diameter is 813mm, wall thickness is 10mm, steel level X65.

The overall formation of frozen soil district oil and gas pipes Monitoring systems is as shown in Figure 2, functional block diagram is as shown in Figure 7. oil and gas pipes 2 surface in frozen soil district 1 and around installation fiber-optical grating temperature sensor 3, 4, the sets of temperature sensors of 5 compositions, fiber grating water content sensor 6 is installed around oil and gas pipes 2, 7, 8, the water content sensor group of 9 compositions, in oil and gas pipes 2 side, fiber grating displacement sensor 10 is installed, 11, all the sensors series connection welding, then guide in monitoring station by optical cable 12, optical cable 12 is connected with photoswitch 13, photoswitch 13 is connected with fiber Bragg grating (FBG) demodulator 14, fiber Bragg grating (FBG) demodulator 14 is connected with lower computer 15, the pretreated data of lower computer 15 transfer to low-orbit satellite 17 by satellite communication module 16, low-orbit satellite 17 forwards the data to satellite communication module 18 after receiving data, the transfer received is carried out treatment and analysis to upper computer 19 by satellite communication module 18, thus realize the safety to frozen soil district oil and gas pipes and monitor.

The electric principle of this example is as shown in Figure 8, fiber-optical grating temperature sensor group, the FC joint of fiber grating water content sensor group and fiber grating displacement sensor group inputs port 1 with the FC of photoswitch respectively, FC inputs port 2, FC inputs port 3 and connects, the R232 port of photoswitch connects the R232 port 1 of lower computer, the FC that the FC output port of photoswitch connects fiber Bragg grating (FBG) demodulator inputs port, the LAN port of fiber Bragg grating (FBG) demodulator connects the LAN port of lower computer, the VGA of lower computer is connected with the VGA of indicating meter, the R232 port 2 of lower computer connects the R232 port of satellite communication module, satellite communication module transfers data to low-orbit satellite, low-orbit satellite forwards the data to another satellite communication module in real time, this satellite communication module will receive data by R232 port transmission to the R232 port of upper computer, upper computer exports indicating meter to after Data Analysis Services to by VGA port.

The fiber-optic grating sensor signal of three types through photoswitch 13 one by one conducting transfer to fiber Bragg grating (FBG) demodulator 14, the centre wavelength that fiber Bragg grating (FBG) demodulator 14 demodulates each fiber-optic grating sensor transfers to lower computer 15, and the cycle of photoswitch 13 conducting signal is controlled by lower computer 15. Data are carried out pre-treatment by lower computer 15, and the data after process are defeated by satellite communication module 16, satellite communication module 16 transfers data to low-orbit satellite 17, low-orbit satellite 17 forwards the data to satellite communication module 18 in real time, satellite communication module 18 will receive transfer to upper computer, data are carried out analyzing and processing by self-programmed software by upper computer, show by indicating meter.

Wherein:

Fiber-optical grating temperature sensor: select the temperature sensor designing encapsulation voluntarily;

Fiber grating displacement sensor: select the displacement sensor designing encapsulation voluntarily;

Fiber grating water content sensor: select the water content sensor designing encapsulation voluntarily;

Optical cable: select middle sky science and technology GYTA-12B1;

Photoswitch: select light grand science and technology SUM-FSW;

Fiber Bragg grating (FBG) demodulator: select SM130;

Lower computer and program: selecting and grind China IPC-610, program is self-editing;

Telstar module: the ST2500 of STELLAR company;

Upper computer and program: selecting and grind China IPC-610, program is self-editing;

Wherein:

The formation of pipeline fiber grating displacement sensor group is as shown in Figure 4. Near pipeline 20, installing fixed link 21, fixed link 21 is deep into permafrost certain depth, can not be moved to ensure. Installing slide block 22 on fixed link 21, slide block 22 is with thin expansion link 23 mode of connection for welding, and thin expansion link 23 stretches in thick expansion link 24, fills butter, to ensure that thin expansion link 23 can move flexibly in thick expansion link 24. Thick expansion link 24 and pipeline 20 are linked together by pipe clamp 25, thick expansion link 24 with pipe clamp 25 mode of connection for welding. Like this, when pipeline 20 is moved, displacement can be passed to thick expansion link 24 by pipe clamp 25, displacement is passed to thin expansion link 23 by thick expansion link 24, displacement is passed to slide block 22 by thin expansion link 23, slide block 22 is connected with fiber grating displacement sensor 26, and wherein fiber grating displacement sensor 26 is large displacement sensor, needs to impose certain pretension when mounted. Fiber grating displacement sensor 26 is connected with data collector by cable junction box 27, it is achieved the monitoring of pipe displacement body.

The formation of frozen soil district fiber-optical grating temperature sensor group is as shown in Figure 5. At pipeline 28 up and down, fiber-optical grating temperature sensor group a29, fiber-optical grating temperature sensor group b30, fiber-optical grating temperature sensor group c31, fiber-optical grating temperature sensor group d32 are installed respectively. Sets of temperature sensors 29 is made up of some fiber-optical grating temperature sensors 33, and the quantity of fiber-optical grating temperature sensor 33 and interval can be arranged according to demand. Connected by single core armouring optical cable 34 between sets of temperature sensors 30 and sets of temperature sensors 32. Fiber-optical grating temperature sensor group a29, fiber-optical grating temperature sensor group b30, fiber-optical grating temperature sensor group c31, fiber-optical grating temperature sensor group d32 are connected with data collector by cable junction box 35, it is achieved the monitoring of pipeline surrounding temperature.

The formation of frozen soil district fiber grating water content sensor group is as shown in Figure 6. Fiber grating water content sensor group 37 is installed in the left side of pipeline 36, fiber grating water content sensor group 38 is installed on the right side of pipeline 36, fiber grating water content sensor group 39 is installed in the downside of pipeline 36.Water content sensor group 37 is made up of some fiber grating water content sensors 40, and the quantity of fiber grating water content sensor 40 and interval can be arranged according to demand. Connected by single core armouring optical cable 41 between water content sensor group 38 and water content sensor group 39. Fiber grating water content sensor group a37, fiber grating water content sensor group b38, fiber grating water content sensor group c39 are connected with data collector by cable junction box 42, it is achieved the monitoring of pipeline surrounding aqueous amount.

As shown in Figure 1, monitoring method is as shown in Figure 2 for monitoring method principle flow chart. oil and gas pipes a2 surface in frozen soil district 1 and around installation fiber-optical grating temperature sensor a3, fiber-optical grating temperature sensor b4, the sets of temperature sensors that fiber-optical grating temperature sensor c5 forms, fiber grating water content sensor a6 is installed around oil and gas pipes a2, fiber grating water content sensor b7, fiber grating water content sensor c8, the water content sensor group that fiber grating water content sensor d9 forms, in oil and gas pipes 2 side, fiber grating displacement sensor a10 is installed, fiber grating displacement sensor b11, all the sensors series connection welding, then guide in monitoring station by optical cable 12, optical cable 12 is connected with photoswitch 13, photoswitch 13 is connected with fiber Bragg grating (FBG) demodulator 14, (FBG) demodulator 14 is connected with lower computer 15, the pretreated data of lower computer 15 transfer to low-orbit satellite 17 by satellite communication module 16, low-orbit satellite 17 forwards the data to satellite communication module 18 after receiving data, the transfer received is carried out treatment and analysis to upper computer 19 by satellite communication module 18, thus realize the safety to frozen soil district oil and gas pipes and monitor.

The monitoring flow process of frozen soil district oil and gas pipes: by fiber-optical grating temperature sensor a3, fiber-optical grating temperature sensor b4, the sets of temperature sensors that fiber-optical grating temperature sensor c5 forms, fiber grating water content sensor a6, fiber grating water content sensor b7, fiber grating water content sensor c8, the water content sensor group that fiber grating water content sensor d9 forms and fiber grating displacement sensor a10, fiber grating displacement sensor b11 is respectively to the temperature around pipeline, moisture and pipe displacement body are monitored, the signal that this monitoring obtains is gathered and pre-treatment by lower computer 15, pretreated data are through teletransmission and reception, to upper computer 19, treatment and analysis is carried out by upper computer 19, judge the safe state of frozen soil district pipeline, carry out pipe temperature field, frozen soil district Dynamic Announce, frozen soil district pipe displacement body Dynamic Announce, Pipeline Water branch, frozen soil district Dynamic Announce, the frozen swell and melt settlement disaster forecast of frozen soil district, the safe early warning of oil and gas pipes.

Temperature around pipeline, moisture and pipe displacement body are monitored by the water content sensor group that the sets of temperature sensors of fiber-optical grating temperature sensor a3, fiber-optical grating temperature sensor b4, fiber-optical grating temperature sensor c5 composition, fiber grating water content sensor a6, fiber grating water content sensor b7, fiber grating water content sensor c8, fiber grating water content sensor d9 form and fiber grating displacement sensor a10, fiber grating displacement sensor b11 respectively; This signal of obtaining of monitoring passes to photoswitch 13 through optical cable 12, reaches lower computer 15 through (FBG) demodulator 14 demodulation, and lower computer 15 calls self-editing program, control photoswitch 13 and (FBG) demodulator 14, it is achieved data are also carried out pre-treatment by the collection of data;Pretreated data transfer to low-orbit satellite 17 by satellite communication module 16, low-orbit satellite 17 forwards the data to satellite communication module 18 after receiving data, the transfer received is carried out treatment and analysis to upper computer 19 by satellite communication module 18, judges the safe state of frozen soil district pipeline.

The process of data completes primarily of software, and software flow (as shown in Figure 3) is: after starting, lower computer data gathering; Photoswitch conducting; Fiber Bragg grating (FBG) demodulator image data; Lower computer data prediction; Satellite communications; Does upper computer judge that whether data complete? if not, then return lower computer data prediction, if then processing and judging that data exceed valve value? if exceeding, then report to the police.

Lower computer data prediction mainly by the optical wavelength data of fiber Bragg grating (FBG) demodulator collection according to being converted into temperature, moisture and displacement data, upper computer is after receiving the data, first data are classified, draw out pipeline surrounding temperature and the trend map of water content and piping displacement thereof, and three monitoring data merge the most at last, judge the steady state in frozen soil district and the safety case of pipeline.

This example is when monitoring, and temperature and moisture need long term monitoring, according to the analysis to long term monitoring data, sums up temperature and change of soil water content state and trend, comprehensively analyzes for pipe and soil interaction and pipeline potential risk judges. Displacement monitoring then can reflect the safe state of pipeline in real time, when there is frozen swell and melt settlement disaster in frozen soil district, it is embedded in the pipeline below the soil body to be subject to frozen soil effect and be subjected to displacement, the displacement monitor that is displaced through of pipeline passes to fiber grating displacement sensor, the data of displacement sensor are transferred to upper computer after lower computer processes and show in real time, piping displacement amount and alarm threshold value are contrasted by the program of upper computer automatically, report to the police when exceeding threshold value.

Through long-time monitoring, this example is easy to build Monitoring systems, is easy to realize the real-time automatic collecting analysis of frozen soil district and pipeline combined monitoring data and long-range issue, long-range warning automatically in real time. Avoid loaded down with trivial details artificial image data, it is to increase the precision of early warning, decrease time of fire alarming, warning place accurately can also be located simultaneously, this to pipeline emergency schedule take most important.

Claims (11)

1. a frozen soil district oil and gas pipes monitoring method, it is characterized in that frozen soil district (1) oil and gas pipes a (2) surface and around multiple fiber-optical grating temperature sensor a (3) is installed, fiber-optical grating temperature sensor b (4), the sets of temperature sensors that fiber-optical grating temperature sensor c (5) forms, multiple fiber grating water content sensor a (6) is installed around oil and gas pipes a (2), fiber grating water content sensor b (7), fiber grating water content sensor c (8), the water content sensor group that fiber grating water content sensor d (9) forms, in oil and gas pipes a (2) side, multiple fiber grating displacement sensor a (10) is installed, fiber grating displacement sensor b (11), all the sensors series connection welding, then guide in monitoring station by optical cable (12), optical cable (12) is connected with photoswitch (13), photoswitch (13) is connected with fiber Bragg grating (FBG) demodulator (14), (FBG) demodulator (14) is connected with lower computer (15), lower computer (15) pretreated data transfer to low-orbit satellite (17) by the first satellite communication module (16), low-orbit satellite (17) forwards the data to the 2nd satellite communication module (18) after receiving data, the transfer received is carried out treatment and analysis to upper computer (19) by the 2nd satellite communication module (18),

The monitoring flow process of frozen soil district oil and gas pipes: multiple fiber-optical grating temperature sensor a (3), fiber-optical grating temperature sensor b (4), the sets of temperature sensors that fiber-optical grating temperature sensor c (5) forms, multiple fiber grating water content sensor a (6), fiber grating water content sensor b (7), fiber grating water content sensor c (8), the water content sensor group that fiber grating water content sensor d (9) forms and multiple fiber grating displacement sensor a (10), the fiber grating displacement sensor group that fiber grating displacement sensor b (11) forms is respectively to the temperature around pipeline, moisture and pipe displacement body are monitored, the signal that this monitoring obtains passes to photoswitch (13) through optical cable (12), lower computer (15) is reached through (FBG) demodulator (14) demodulation, lower computer (15) calls self-editing program, control photoswitch (13) and (FBG) demodulator (14), it is achieved data are also carried out pre-treatment by the collection of data, pretreated data transfer to low-orbit satellite (17) by the first satellite communication module (16), low-orbit satellite (17) forwards the data to the 2nd satellite communication module (18) after receiving data, the transfer received is carried out treatment and analysis to upper computer (19) by the 2nd satellite communication module (18), judge the safe state of frozen soil district pipeline, to the safe early warning of the forecast of frozen soil district frozen swell and melt settlement disaster, oil and gas pipes, wherein, described fiber-optical grating temperature sensor a (3), described fiber-optical grating temperature sensor b (4), described fiber-optical grating temperature sensor c (5) all adopt the structure of double-layer pipe,

The process of data completes primarily of software, and its flow process is: after starting, lower computer data gathering; Photoswitch conducting; Fiber Bragg grating (FBG) demodulator image data; Lower computer data prediction; Satellite communications; Does upper computer judge that whether data complete? if not, then return lower computer data prediction, if then processing and judging that data exceed valve value? if exceeding, then report to the police.

2. a kind of frozen soil district according to claim 1 oil and gas pipes monitoring method, is characterized in that described piping displacement monitoring method is: pipe displacement body is monitored by multiple fiber grating displacement sensor a (10), fiber grating displacement sensor b (11); The signal that this monitoring obtains is gathered and pre-treatment by lower computer (15), pretreated data are through teletransmission and reception, to upper computer (19), treatment and analysis is carried out by upper computer (19), judge the safe state of frozen soil district pipeline, carry out pipe temperature field, frozen soil district Dynamic Announce, frozen soil district pipe displacement body Dynamic Announce, Pipeline Water branch, frozen soil district Dynamic Announce; To the safe early warning of the forecast of frozen soil district frozen swell and melt settlement disaster, oil and gas pipes;

Judge pipeline whether safety, only the axis stress of pipeline and pipe body yielding stress need to being contrasted, if exceeding yielding stress, then reporting to the police; The calculation formula between displacement y and conduit axis stress �� of pipeline is as follows:

When calculating, pipeline is regarded the beam of the semi-infinite space as, according to the STRESS VARIATION of ground beam theory qualitative analysis pipeline;

Piping displacement y curve is:

$y=-\frac{2\mathrm{\&Delta;}}{1^3}{x}^3+\frac{3\mathrm{\&Delta;}}{1^2}{x}^2---\left(1\right)$

The calculation formula of moment M:

$M=-{\mathrm{EI}}_z\frac{d^{2}y}{{\mathrm{dx}}^2}---\left(2\right)$

Formula (1) is substituted into formula (2) obtain:

$M={\mathrm{EI}}_z(\frac{6\mathrm{\&Delta;}}{1^2}-\frac{12\mathrm{\&Delta;}}{1^3}x)---\left(3\right)$

I_zFor beam section moment of inertia, I_zCalculation formula be:

$I_z={\mathrm{\&pi;R}}^3\mathrm{\&delta;}+\frac{3}{2}{\mathrm{\&pi;R}}^2{\mathrm{\&delta;}}^2+{\mathrm{\&pi;R\&delta;}}^3+\frac{1}{4}{\mathrm{\&pi;\&delta;}}^4---\left(4\right)$

The then axis stress �� of pipeline section:

$\mathrm{\&sigma;}=\frac{My}{I_z}---\left(5\right)$

In formula: E is tubing Young's modulus; R is internal diameter of the pipeline, and �� is pipeline wall thickness;

According to the displacement y that pipeline occurs, calculate the axis stress �� of pipeline, �� and pipeline yielding stress are contrasted, judges the safe state of pipeline.

3. a kind of frozen soil district according to claim 1 oil and gas pipes monitoring method, is characterized in that described frozen soil district temperature monitoring method is: the temperature around pipeline is monitored by the sets of temperature sensors being made up of multiple fiber-optical grating temperature sensor a (3), fiber-optical grating temperature sensor b (4), fiber-optical grating temperature sensor c (5); The signal that this monitoring obtains is gathered and pre-treatment by lower computer (15), pretreated data are through teletransmission and reception, to upper computer (19), treatment and analysis is carried out by upper computer (19), judge the safe state of frozen soil district pipeline, carry out pipe temperature field, frozen soil district Dynamic Announce, frozen soil district pipe displacement body Dynamic Announce, Pipeline Water branch, frozen soil district Dynamic Announce; The frozen swell and melt settlement disaster forecast of frozen soil district; The safe early warning of oil and gas pipes;

The year-round average temperature bottom soil temperature year change layer is adopted to represent and contrast frozen soil layer temperature; First the temperature value that each position is measured is depicted as curve according to the degree of depth, on temperature curve, order is got a little, the degree of depth and the Temperature numerical put each substitute into formula (6), and till equation two ends are equal, the temperature thus drawn is year-round average temperature T_c, the depth value drawn adds that the Seasonal analysis degree of depth is the year varying depth D of soil temperature;

$In\frac{t_{cp}}{0.1}=Z\sqrt{\frac{\mathrm{\&pi;}}{KT}}---\left(6\right)$

In formula: t_cpFor mean annual cost (DEG C); Z is year varying depth (m) of soil temperature; K is soil layer thermal diffusivity (cm2 s-1); T is annual cycle (s);

Calculate soil layer year varying depth D according to radical (6), learn that pipeline is to the range of influence of frozen soils temperature field, and then calculated under this kind of impact that pipeline is contingent melts heavy situation further by finite element method.

4. a kind of frozen soil district according to claim 1 oil and gas pipes monitoring method, is characterized in that described frozen soil district water content monitoring method is: the moisture around pipeline is monitored by the water content sensor group being made up of multiple fiber grating water content sensor b (7), fiber grating water content sensor c (8), fiber grating water content sensor d (9); The signal that this monitoring obtains is gathered and pre-treatment by lower computer (15), pretreated data are through teletransmission and reception, to upper computer (19), treatment and analysis is carried out by upper computer (19), judge the safe state of frozen soil district pipeline, carry out the safe early warning of pipe temperature field, frozen soil district Dynamic Announce, permafrost forecast, oil and gas pipes;

When frost heave disaster occurs, only could produce frost heave when foundation soil water content exceedes certain boundary value; Usually this Atterberg limits is called initial frost heaving amount W_o, the plastic limit water content of soil is W_p, the natural aqueous value of soil that water content sensor is measured is W, then, when W meets following formula, strong frost heave will occur the soil body;

W_p+5<W��W_p+15(7)

In formula: W_pFor soil plastic limit water content, obtain by experiment;

By formula in the observed value W substitution of water content sensor, when the condition is satisfied, system just can be reported to the police automatically.

5. one kind uses the frozen soil district oil and gas pipes Monitoring systems of method described in claim 1, it is characterized in that this system is divided into on-site data gathering transmission subsystem and data analysis display subsystem, specifically comprise fiber grating displacement sensor group, fiber-optical grating temperature sensor group, fiber grating water content sensor group, field monitoring station, remote monitoring center;

Totally being configured to of frozen soil district oil and gas pipes Monitoring systems: in frozen soil district 1 oil and gas pipes a (2) surface and around multiple fiber-optical grating temperature sensor a (3) is installed, fiber-optical grating temperature sensor b (4), the sets of temperature sensors that fiber-optical grating temperature sensor c (5) forms, multiple fiber grating water content sensor a (6) is installed around oil and gas pipes a (2), fiber grating water content sensor b (7), fiber grating water content sensor c (8), the water content sensor group that fiber grating water content sensor d (9) forms, in oil and gas pipes a (2) side, multiple fiber grating displacement sensor a (10) is installed, fiber grating displacement sensor b (11), all the sensors series connection welding, then guide in monitoring station by optical cable (12), optical cable (12) is connected with photoswitch (13), photoswitch (13) is connected with fiber Bragg grating (FBG) demodulator (14), fiber Bragg grating (FBG) demodulator (14) is connected with lower computer (15), lower computer (15) pretreated data transfer to low-orbit satellite (17) by the first satellite communication module (16), low-orbit satellite (17) forwards the data to the 2nd satellite communication module (18) after receiving data, the transfer received is carried out treatment and analysis to upper computer (19) by the 2nd satellite communication module (18), thus realize the safety to frozen soil district oil and gas pipes and monitor,Wherein, described fiber-optical grating temperature sensor adopts the structure of double-layer pipe;

Multiple fiber-optical grating temperature sensor a (3), fiber-optical grating temperature sensor b (4), fiber-optical grating temperature sensor c (5), fiber grating water content sensor a (6), fiber grating water content sensor b (7), fiber grating water content sensor c (8), fiber grating water content sensor d (9), fiber grating displacement sensor a (10), fiber grating displacement sensor b (11) is respectively by the temperature around pipeline, moisture and pipe displacement body signal pass to photoswitch (13) through optical cable (12), lower computer (15) is reached through fiber Bragg grating (FBG) demodulator (14) demodulation, lower computer (15) calls self-editing program, control photoswitch (13) and fiber Bragg grating (FBG) demodulator (14), realize the collection of data and data are carried out pre-treatment, pretreated data transfer to low-orbit satellite (17) by the first satellite communication module (16), low-orbit satellite (17) forwards the data to the 2nd satellite communication module (18) after receiving data, the transfer received is carried out treatment and analysis to upper computer (19) by the 2nd satellite communication module (18), judges the safe state of frozen soil district pipeline.

6. a kind of frozen soil district according to claim 5 oil and gas pipes Monitoring systems, is characterized in that its functional block diagram is: it is divided into on-site data gathering transmission subsystem and data analysis display subsystem; System comprises again displacement monitor, device for detecting temperature and water content monitoring device three part; The composition of on-site data gathering transmission subsystem is: the output of fiber grating displacement sensor, fiber-optical grating temperature sensor and fiber grating water content sensor connects the input of photoswitch, the output of photoswitch connects the input of fiber Bragg grating (FBG) demodulator, fiber Bragg grating (FBG) demodulator exports the input connecing lower computer, and lower computer exports and connects satellite communication module; On-site data gathering transmission subsystem is linked by low-orbit satellite and data analysis display subsystem; The composition of data analysis display subsystem is: satellite communication module exports the input connecing upper computer, and upper computer exports frozen soil district temperature field Dynamic Announce, frozen soil district piping displacement Dynamic Announce, moisture field, frozen soil district Dynamic Announce.

7. a kind of frozen soil district oil and gas pipes Monitoring systems according to claim 5 or 6, it is characterized in that the electric principle of this system is: fiber-optical grating temperature sensor group, the FC joint of fiber grating water content sensor group and fiber grating displacement sensor group inputs port 1 with the FC of photoswitch respectively, FC inputs port 2, FC inputs port 3 and connects, the R232 port of photoswitch connects the R232 port 1 of lower computer, the FC that the FC output port of photoswitch connects fiber Bragg grating (FBG) demodulator inputs port, the LAN port of fiber Bragg grating (FBG) demodulator connects the LAN port of lower computer, the VGA of lower computer is connected with the VGA of indicating meter, the R232 port 2 of lower computer connects the R232 port of satellite communication module, satellite communication module transfers data to low-orbit satellite, low-orbit satellite forwards the data to another satellite communication module in real time, this satellite communication module will receive data by R232 port transmission to the R232 port of upper computer, upper computer exports indicating meter to after Data Analysis Services to by VGA port,

The fiber-optic grating sensor signal of three types through photoswitch (13) one by one conducting transfer to fiber Bragg grating (FBG) demodulator (14), the centre wavelength that fiber Bragg grating (FBG) demodulator (14) demodulates each fiber-optic grating sensor transfers to lower computer (15), and the cycle of photoswitch (13) conducting signal is controlled by lower computer (15);Data are carried out pre-treatment by lower computer (15), and the data after process are defeated by the first satellite communication module (16), first satellite communication module (16) transfers data to low-orbit satellite (17), low-orbit satellite (17) forwards the data to the 2nd satellite communication module (18) in real time, 2nd satellite communication module (18) will receive transfer to upper computer (19), data are carried out analyzing and processing by self-programmed software by upper computer (19), show by indicating meter.

8. a kind of frozen soil district oil and gas pipes Monitoring systems according to claim 5 or 6, is characterized in that described fiber grating displacement sensor adopts temp. compensation type structure; Fiber grating water content sensor is made up of vitrified-clay pipe and vacuum box, and vitrified-clay pipe is sensor.

9. a kind of frozen soil district according to claim 5 oil and gas pipes Monitoring systems, it is characterized in that the formation of described pipeline fiber grating displacement sensor group is: near pipeline b (20), installing fixed link (21), fixed link (21) is deep into permafrost certain depth; Fixed link (21) is installed slide block (22), slide block (22) with thin expansion link (23) mode of connection for welding, thin expansion link (23) stretches in thick expansion link (24), fills butter in thick expansion link (24); Thick expansion link (24) and pipeline b (20) are linked together by pipe clamp (25), thick expansion link (24) with pipe clamp (25) mode of connection for welding; Slide block (22) is connected with fiber grating displacement sensor c (26), and wherein fiber grating displacement sensor c (26) is large displacement sensor, needs to impose certain pretension when mounted; Fiber grating displacement sensor c (26) is connected with data collector by cable junction box a (27).

10. a kind of frozen soil district according to claim 5 oil and gas pipes Monitoring systems, it is characterized in that the formation of described frozen soil district fiber-optical grating temperature sensor group is: at pipeline c (28) up and down, fiber-optical grating temperature sensor group a (29), fiber-optical grating temperature sensor group b (30), fiber-optical grating temperature sensor group c (31), fiber-optical grating temperature sensor group d (32) are installed respectively; Fiber-optical grating temperature sensor group a (29) is made up of some fiber-optical grating temperature sensor d (33), and quantity and the interval of fiber-optical grating temperature sensor d (33) are arranged according to demand; Connected by single core pin dress optical cable (34) between fiber-optical grating temperature sensor group b (30) and fiber-optical grating temperature sensor group d (32); Fiber-optical grating temperature sensor group a (29), fiber-optical grating temperature sensor group b (30), fiber-optical grating temperature sensor group c (31), fiber-optical grating temperature sensor group d (32) are connected with data collector by cable junction box b (35).

11. a kind of frozen soil district according to claim 5 oil and gas pipes Monitoring systemss, it is characterized in that the formation of described frozen soil district fiber grating water content sensor group is: fiber grating water content sensor group a (37) is installed in the left side of pipeline d (36), fiber grating water content sensor group b (38) is installed on the right side of pipeline d (36), fiber grating water content sensor group c (39) is installed in the downside of pipeline d (36); Fiber grating water content sensor group a (37) is made up of some fiber grating water content sensors (40), and quantity and the interval of fiber grating water content sensor (40) are arranged according to demand; Connected by single core pin dress optical cable (41) between fiber grating water content sensor group b (38) and fiber grating water content sensor group c (39);Fiber grating water content sensor group a (37), fiber grating water content sensor group b (38), fiber grating water content sensor group c (39) are connected with data collector by cable junction box c (42).