Dual Lasers in DTS Systems for Oil and Gas Wells

DTS systems provide the oil and gas and other industries with the new cutting-edge fiber optic solutions such as a groundbreaking dual laser technology which offers the most robust and the simplest distributed temperature sensing systems accessible to the industry. This technology also includes the ability of the automatic correction for dynamic changes to the sensing fiber.

What is Distributed Temperature Sensing?

Distributed temperature sensing, also known as DTS, is a technology that measures the temperature along the whole fiber optic cable in a continuous fashion. The fiber optic line can be any required length up to 30 km. The system includes the recording instrumentation at one or both ends of the cable. It can work permanently or from time to time for each use, depending on the requirements.Dual Lasers in Distributed Sensing Systems

Most Common DTS Applications

Distributed sensing systems have established themselves as an effective part of fiber optic technology. High temperatures are related to the severe environmental conditions which make operational processes difficult. However, fiber optic sensors can operate in such conditions greatly, especially, if we compare them with the electrical-based temperature sensors. That’s why fiber optic systems have found many applications, such as fire detection, healthcare, railways, etc.

DTS systems are installed on the electric power lines to monitor temperature changes. The temperature may indicate the electrical overload or other deviations from the norm in time. DTS technology allows power companies to exploit the assets more effectively.

With the help of constant monitoring, it is easy to react immediately to the temperature rising. When this rising is above a predefined threshold, the alarm sets off. The early detection and warning lead to reduction of the damage that failures may cause.

DTS Applications in the Oil and Gas Industry

Fiber optic technology has been used in the oil and gas industry for over the last 25 years. Fiber optic systems were installed in various types of oil wells starting from land wells and ending with offshore wells. Fiber optic technology allows watching down hole casing deformation or changes in sand screen completions.

Thanks to its operational principles, distributed temperature sensing offers critical asset monitoring solutions that can be applied for oil and gas companies. DTS systems immediately provide the actual and accurate information about temperature with high resolution and high speed. Fiber optic cable provides specialists with the numerous measurement readings along the whole optical fiber. This feature helps companies in detecting leaks along the pipelines, whether along its length or anywhere on the cross-section. The faster the leaks are found, the less damage can be. It means considerable cost savings for companies. Moreover, DTS technology helps in identifying under-performing zones, optimizing gas lift operations, etc.

Distributed temperature sensing has been applied safely to follow up pressure or reactor vessels. Depending on the required set-ups, the temperature measurements can be held as frequently as every 30 seconds. Any changes in temperature may point out some problems that have occurred. So the increasing temperature of the vessel wall usually predicts the system or the process failure.

Dual Lasers in DTS Systems

Each year, specialists implement DTS systems more often to make the efficiency of production better. The integration of the dual lasers into such systems is a new technology, aiming at the life extension of optical fibers and solving the most appearing concerns. The most common issues that optical fibers face are fiber darkening or their damage.

The fiber darkening can misrepresent the statements and lead to the failure of the DTS system. It occurs where there are high pressure and high temperature environments that are usual for oil wells. The darkening happens unevenly and is progressive over time that makes the manual calibration techniques ineffective. Moreover, different connectors on the fiber can result in various degrees of optical loss. Two lasers operate at different wavelengths, so there is an automated adjusting system for any changes in optical loss in the fiber. They immediately react and correct these effects which allows the further use without re-installation of the whole system from the very beginning.

Such fiber optic systems help in cost-reducing by avoiding the re-deployment of the equipment. Despite the other systems, they don’t need the manual calibration techniques, but operate automatically all over the length. The manual calibration usually requires repeated recalibration efforts.

Newly developed DTS systems with dual lasers offer great advantages especially where there is no or limited access to the optical fiber. They help to extend the lifetime of the fiber and ease fiber optic systems’ deployment.

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) product line such as fiber Bragg grating sensors, for example, fbg strain sensors, FBG interrogators and multiplexers, Distributed Acoustic Sensing (DAS) systems, Distributed Temperature Sensing (DTS) systems. The company creates and supplies a broad variety of fiber optic solutions for monitoring worldwide. If you are interested in structural health monitoring systems and want to learn more, please contact us at info@optromix.com

Distributed Temperature Sensing at shallow depths

Distributed temperature sensing (DTS) is a state-of-the-art tool that possess an ability to monitor temperature rates over large territory and across wide temporal scales. This fiber optic technology has proved to be effective in different spheres and industries. However, despite the long field experience story, it still has its limitations and challenges apart from all the advantages. For example, when we talk about its application at shallow or deep depths.

DTS at shallow depths

The main difficulties in Distributed Temperature Sensing application

Despite all the progress that was achieved during this decade, distributed temperature sensing still meets some challenges. For example, when applied to the ocean, since dynamic oceanographic processes have a wide range of parameters, ranging from various types of turbulence to different climates, all data obtained from DTS systems fully help in understanding the dynamics of a complex ocean. However, different constraints can make modifications in time scales creating restrictions. Furthermore, there is a need for many additional advanced equipment for broad spatial resolution. That’s why it’s still complicated to use DTS in oceanography. However, now there are cases when distributed temperature sensing (DTS) is applied, for instance, in the Atlantic.

Recently, the scientists announced the first experiments on the seafloor of the Arctic sea ice with the help of the distributed acoustic sensing (DAS) system. This research has shown that fiber optic technology is effective, despite all the difficulties the scientists have faced due to the harsh environment. The system recorded a range of events that commonly applied equipment couldn’t even detect. Moreover, the DAS technology has detected the icequakes, various climate signals, and marine life.

From the other side, DTS systems can be applied in measuring surface water temperature spatial variability in lakes and rivers. The received data helps in the assessment of different factors such as estimating fish habitat and thermal inertia, the interaction between surface water and groundwater, etc. Usually, distributed temperature sensing is successfully applied in rivers and lakes with sensitive and high-resolution temperature monitoring under the wide temporal and spatial scales. Nevertheless, difficulties may arise in streams with cobbly or bedrock-lined streambeds. To avoid all the challenges, more expensive additional technologies are needed.

There are other factors that should be ensured like sensitive equipment needs protection and continuous power to work. Besides, optical fibers are delicate, they shouldn’t be bent or crimped.

How the Distributed sensing system works

Distributed sensing systems are appealing because they are able to continuously sample preserving while maintaining relatively high temporal and spatial resolution. Moreover, the accuracy indicators stay the same over a vast territory.

Distributed temperature sensors measurement allows to constantly observe temperature changes along the fiber optic cable. In this fiber optic technology the whole cable plays the role of the sensing element that measures temperature. It differs this method from the usual electrical temperature measurement. Moreover, the distributed temperature sensing is regarded as the most cost-effective and efficient system among the modern temperature measurement technologies.

The main operation principles of measurement are built on detecting the back-scattering of light:

        1. The first type is an optical fiber that uses Raman scattering. This approach was invented in the United Kingdom. Optical fibers are usually made from doped quartz glass. When the light falls on the excited molecular oscillations, the electrons of the molecule and the electrons of the molecule start interaction. This process is called Raman scattering and results in scattered light.
        2. The second method is the Brillouin scattering-based approach. It was mostly developed in the 1990s. It refers to the scattering of a light wave by an acoustic wave because of the interaction with the acoustic phonons. Thanks to the ability of the Brillouin scattering of making both frequency down- and up-shifted light, this method can be applied whether for distributed temperature or strain sensing. It can contain both, but they can’t work at the same time.
        3. The third technique is named Rayleigh back-scattering. This is the latest development. As well as for the previously developed distributed sensors, a usual optical fiber can be used as the sensor. It allows the entire cable to be used as a single sensor, without purchasing expensive individual sensors. Scientists applied this technique, for example, for measuring distributed temperature in a nuclear reactor.

If we compare all these three techniques, each of them has its pros and cons. According to the scientists, the Rayleigh scattering demonstrates the highest rates in comparison with other types. However, it has limits in a range of fiber length. This factor is crucial for long lengths of cables’ monitoring. For this characteristic, the Brillouin scattering shows the best results. Besides, it has temperature sensitivity and good measurement time. Moreover, Brillouin scattering allows to detect distributed strain, unlike the other two methods. But usually it is applied either for distributed temperature measurement or strain. According to the data, Brillouin scattering is more often used as a substitute for Raman scattering.

DTS systems in field experiments

In accordance with the final field experiments, despite all the challenges, temperature measurements with the help of the DTS systems have been performed successfully in various environments including rivers, lakes, seas, etc. The fiber Bragg grating sensors have been applied both in fresh and sea water and demonstrated good results. Furthermore, it refers to simultaneous measurement of temperature and depth which has been impossible for previous fiber sensors.

Modern fiber optic sensors provide the parallel measurements of temperature and pressure at the same place. Besides, in comparison with other methods, fiber optic technology provides much lower power consumption. It allows the DTS systems to work longer and makes longer experiments and observation possible.

The developed fiber optic technology can be used for measurements and monitoring of the physical parameters. Moreover, it is well-placed for many cases and can be applied to various applications, such as wave and tide gauges, tsunami warning systems, etc.

All in all, we can say that distributed temperature sensing (DTS) can be successfully applied in various cases at shallow depths due to their diversity. The system can be designed and installed in accordance with the existing conditions and parameters in every single case.

Optromix is a DTS system manufacturer that provides top of the line distributed temperature sensing systems suitable for monitoring commerce networks. If you have any questions or would like to buy a DTS system, please contact us at info@optromix.com

Fiber Optic Sensing Systems for Oil and Gas Wells

Fiber optic sensing systems can greatly assist in the exploitation of oil and gas resources. During the downhole processing, technicians can face a variety of technical challenges resulting from difficult environmental conditions. Wellbore structural health monitoring is a substantial system that provides the profitability and reliability of these fields.

Fiber Bragg grating sensors have replaced traditional electronic sensors for reservoir monitoring and downhole production. In-well sensors are applied for measuring a range of parameters such as flow rate, pressure, temperature, fraction, seismic response, etc. Fiber Bragg gratings have proven themselves as reliable and accurate technology that can be applied in multilateral wells. These systems are installed in different operating environments all over the world.Fiber Optic Sensing Systems for Oil and Gas Wells

Distributed Fiber Optic Monitoring Systems’ Elements

Thanks to all the benefits, including a wide range of working temperatures and pressures, immunity to electromagnetic interference, and the possibility of usage in an adverse environment, fiber optic solutions have found many applications.

Any fiber optic sensing system consists of three components:

  • Fiber optic cable is suited to measure some physical effects with high absolute and local accuracy. Usually, cables are produced in such a way that the scattering effects are minimized. That allows maximizing transmission distance and data rate.
  • Analyzer or control panel is connected to the fiber optic cable and is designed to capture and collect data.
  • The final step is the interpretation and analysis of the whole received sensor data with the usage of the software. The software allows users to visualize strain or temperature data from the system.

The Most Common Fiber Optic Sensing Systems

There are two main types of fiber optic sensing systems: distributed acoustic sensing systems and distributed temperature sensing systems. Both of them have proven to be the most cost-effective and reliable fiber optic solutions and found their applications, including in the oil and gas industry. The main advantage of these systems is the ability to measure at each position where the fiber optic cable is installed.

Distributed Acoustic Sensing

DAS systems are optoelectronic instruments based on fiber optic technology that measures acoustic interactions all over a fiber optic cable. In DAS there is also an attached optoelectronic device that processes all the data from the cable. This technique allows acoustic frequency strain signals to be detected in harsh environmental conditions and over large distances. The sensing fiber is usually built on single-mode fiber. However, multimode sensing fibers can be also applied in some customized applications.

Distributed Temperature Sensing

DTS systems are optoelectronic instruments based on fiber optic technology that measures temperature all over a fiber optic cable. One of its advantages is providing continuous temperature information along the whole sensing cable. Moreover, specialists can predetermine the discrete sensing points for the most accurate data.

Nowadays, scientists are working in other directions. Since the invention of fiber optic technology, significant improvements have been made in both technologies and sensors. But for now, it is complicated to project a system that would combine DAS and DTS systems with the same optical fiber because of the different operation principles.

Optromix is a DTS system manufacturer that provides top of the line distributed temperature sensing systems suitable for monitoring commerce networks. If you have any questions or would like to buy a DTS system, please contact us at info@optromix.com

Distributed Temperature Sensing (DTS) for ice sheets

Scientists from the UK have applied fiber optic systems to observe the Greenland ice sheet and get the most accurate measurements of ice characteristics. They chose distributed temperature sensing (DTS) as the main instrument for collecting data about the ice sheets melting. The results will be used to build more precise movement models of the second-largest ice sheet in the world.

Nowadays, the Greenland Ice Sheet plays a crucial role in the rising global sea level. The main reasons for the Ice Sheet’s mass loss are the meltwater runoff and the discharge of ice into the ocean by the glaciers. That’s why the scientists chose it for the research with the help of fiber optic systems.

The researchers applied modern fiber optic technology in order to determine the ice sheet movement. To discover thermodynamic processes within a glacier, they used distributed temperature sensing (DTS). According to the research, this fiber optic system consists of a 1000 meters length fiber optic cable that transmits laser pulses. In comparison with the previous researches, when the temperature was measured with separate sensors far away from each other, the fiber optic technology measures the temperature along the entire fiber optic cable. As a result, the scientists get a really detailed profile of ice sheet temperature.

First of all, the scientists drill through the glacier to install the fiber optic cable. Then they put it into the borehole. The research team transmits laser pulses in the fiber optic cable and writes any light changes down. The light changes demonstrate the different temperatures of the surrounding ice. And the last step is collecting the data and its analysis.

Thanks to the distributed fiber optic sensors, scientists have already found that the temperature distribution is diverse. This deformation is concentrated on the lines of ice that belong to different ages and types. Researchers suppose that it can be caused by the dust content of the ice or large fractures.

The great advantage of this fiber optic technology is the fact that the temperature can be recorded over vast distances and at high resolution. The scientists are working on the other aspects that could be useful in future research, for example, deformation.

The received data collected with the help of distributed temperature sensing systems allows developing advanced designs and models of the ice sheet movement. Fiber optic technology also will help to predict its movements in the future and define the approximate sea level rise.

Optromix is a DTS system manufacturer that provides top of the line distributed temperature sensing systems suitable for monitoring commerce networks. If you have any questions or would like to buy a DTS system, please contact us at info@optromix.com

Distributed Sensing market and its growth forecast

Distributed Sensing market forecastAccording to the researchers, the distributed sensing market is predicted to reach more than $891 million by 2026. The distributed temperature sensing power cables and distributed acoustic sensing systems, as well as global environmental changes, are expected to increase the demand significantly. The modern advancements and developments connected with the light-sized fiber optic systems stimulate globally the distributed sensing market. Moreover, the growth of the distributed sensing market can also be explained by the government’s support for distributed temperature sensing technology.

Nowadays, there are many appliances of distributed sensing systems. There is an extensive need for monitoring continuous temperature changes within big territories and long distances, for example, in the oil sphere. The distributed temperature sensing systems are also applied in subsea areas. Distributed sensing can also help in providing security and productivity in different market sectors in the upcoming years. Moreover, fiber optic solutions are more often applied in fire detection processes.

In April the newly developed fiber optic system got a reward for the innovative approach and commercialization. The fiber optic system expands the coverage of distributed sensors. As a result, this innovation gives new possibilities in many fields such as energy, infrastructure, and environmental sectors. This fiber optic technology allows the collection of more precise data. That could lead to the improvement of sustainability, enhancing operational safety, and getting optimal costs for existing and new applications.

Distributed fiber optic sensors offer sensitivity 100 times greater than the usual ones. The higher sensitivity solves the emerging critical problem and challenges fast. That allows monitoring the situation continuously. This fiber optic technology also provides all the advantages such as carbon capture, improved geothermal systems, and dam integrity monitoring as well as subsea oil and gas wells.

In conclusion, distributed sensing systems are a very promising technology for many sectors. Thanks to the distributed sensors that are extremely sensitive to any slight changes, they can provide the most precise picture in comparison with other modern technologies.

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) product line such as fiber Bragg grating sensors, for example, FBG strain sensors, FBG interrogators and multiplexers, Distributed Acoustic Sensing (DAS) systems, Distributed Temperature Sensing (DTS) systems. The company creates and supplies a broad variety of fiber optic solutions for monitoring worldwide. If you are interested in structural health monitoring systems and want to learn more, please contact us at info@optromix.com

Distributed Temperature Sensing (DTS) measures moisture

DTS for moisture estimationPassive distributed temperature sensing (DTS) helps to improve the measurement of moisture content and temperature increase. The DTS technology has been already tested in China to prove the opportunities provided by this technique. Therefore, distributed temperature sensors are very promising for agriculture.

Several land conditions include bare soil, plastic mulch, plastic mulch covered with potatoes, and plastic much covered with maize. Land moisture plays a crucial role in influencing grain yield. Nevertheless, distributed temperature sensing is not suitable for the last type of land.

The thing is that several techniques allow for determining soil moisture content. Distributed sensing systems include point, ground, and regional types. Herewith, point fiber optic sensors consist of “oven-drying, neutron scattering, electrical impedance, time-domain reflectometry (TDR), frequency domain reflectometry (FDR), tensiometer, and thermal probe techniques.”

Conventional fiber sensors offer benefits of high precision and reliability but most of them are limited to a specific area. This is the main reason why it is difficult to determine accurately the overall ground moisture condition, especially in places where soil moisture distribution is discontinuous.

Thus, scientists have suggested applying distributed temperature sensing (DTS). DTS technology allows for estimating agricultural soil moisture, herewith, the distance of measurement can achieve several tens of kilometers. The operating principle of distributed temperature sensors is based on the heating of optical cables. When the temperature increases, the soil moisture can be estimated.

The DTS technology is not new and it quickly found the application in moisture measurement. According to this technique, it is possible to measure in situ soil moisture by employing analytical or semi-empirical models. Nevertheless, firstly it is necessary to calculate the thermal conductivity of the soil.

Compared to traditional techniques that have limitations, distributed temperature sensing allows for overcoming them. DTS estimates the temperature response of soil, therefore, measures soil moisture based on the data obtained by fiber optic sensors. Nonetheless, the proposed technique has several disadvantages.

Various weather conditions can influence the heat transfer way in the soil and the data obtained by distributed temperature sensors will be inaccurate. Additionally, boundary conditions and even time change periods also influence the precision. Finally, the standard algorithm is very difficult for application in practice.

Optromix is a DTS system manufacturer that provides top of the line distributed temperature sensing systems suitable for monitoring commerce networks. If you have any questions or would like to buy a DTS system, please contact us at info@optromix.com

Distributed temperature sensing (DTS) in oceanography

DTS in oceanographyThe technology of distributed temperature sensing (DTS) is based on the application of Raman scattering from a laser beam light through optical fibers to detect temperature parameters along a fiber optic cable. The thing is that temperature resolution plays a crucial role. Herewith, this feature makes it possible to efficiently use DTS systems in oceanography.

Even though oceanographic applications of distributed temperature sensing are not new but such observations are not often. The reason is the serious challenges of deployment, calibration, and operation in oceanographic environment conditions. Nevertheless, researchers have tested the DTS system to overcome oceanographic configuration, calibration, and data processing difficulties.

It should be noted that they also evaluate temperature errors of DTS for several common scenarios. Difficult conditions influence the whole process, thus, the researchers look for alternative calibration, analysis, and deployment methods for distributed temperature sensing.

Therefore, these errors will be reduced and the successful application of DTS systems will be increased in dynamic ocean conditions. The thing is that DTS technology allows for “continuously sampling at a relatively high temporal and spatial resolution for significant duration over broad spatial scales.”

Despite distributed temperature sensing is widely applied in environmental applications, the oceanographic area remains challenging and still relatively rare. The main purpose of new DTS development is the solution to common problems present in oceanographic deployments.

To be more precise, the researchers use 2 various DTS systems, 3 fiber optic cables, and 24 thermistors. All of them help to test cables and different calibration configurations and perform distributed temperature sensing. Test results enable them to improve future oceanographic deployments. Moreover, they aid to achieve the best possible temperature signal in difficult deployment and operational environments.

DTS technology is a relatively new oceanographic tool. It allows for detecting temperature across wide spatial and temporal scales. Herewith, the application of such a fragile DTS system in remote and dynamically complex conditions remains difficult. Moreover, sometimes it is impossible to perform distributed temperature sensing at all.

Additionally, DTS systems face challenges during the detection of air/sea boundary. The reason is the change of water level, for instance, tides, waves, surge, etc., when the fiber optic cable can be exposed. Finally, the new DTS has succeeded to detect the temperature variance between the air-sea interface.

If you want to obtain a highly efficient distributed temperature sensing system, you should choose the Optromix company. Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for monitoring worldwide. Optromix is a fast-growing vendor of fiber Bragg grating (FBG) products line such as fiber Bragg grating sensors, FBG interrogators and multiplexers, distributed acoustic sensing (DAS) systems, distributed temperature sensing (DTS) systems. If you are interested in DTS systems and want to learn more, please contact us at info@optromix.com

Why DTS systems are beneficial to pipelines

DTS for pipelinesAlmost all pipelines suffer from numerous leaks during their operation, therefore, they require systems for fiber optic pipeline leak detection. Despite the fact that there are various techniques for leak detection, distributed temperature sensing systems (DTS) are considered to be an ideal option for the purpose.

Distributed temperature sensing is a technique that has been applied for more than two decades. DTS systems are regarded as the best option when a leak leads to a temperature differential between the ambient air and the escaping liquid or gas. The thing is that “temperature differentials generally occur when the pipeline product is at high pressure, high temperature or low temperature, all relative to ambient, which is characteristic of numerous pipelines.”

The operating principle of DTS is based on fiber optic sensing systems that operate as a sensor and measure temperatures along the entire length of optical fibers. Herewith, the optical fiber is put along the outside of the pipeline within the protective coating. It should be noted that the accurate installation location depends on the relative area(s) of the anticipated temperature differential caused by a leak, and on other reasons such as available mounting space.

To be more precise, DTS systems allow fastly identifying and precisely locating slow leaks at weld points, pipeline fittings, and herewith, sudden leaks. Fiber optic pipeline leak detection system enables detecting the precise location of leaks, often overcoming other distributed sensing technology. The fact is that even a tiny leak leads to a crucial temperature change, one that can be recorded by the DTS system.  Most DTS measures temperatures with a precision of a few degrees, more than sufficient for leak detection.

For instance, a modern leading distributed temperature sensing technology allows measuring temperatures at a distance of 6 km, totaling 6000 points of measurement. The fiber optic sensing system’s transceiver measures “temperatures for 6 km both upstream and downstream of its installation point, for a total coverage of 12 km per each transceiver.” It is possible to employ several transceivers with accompanying fiber optic cables to offer coverage for long pipelines, totaling hundreds or thousands of kilometers in distance.

DTS technology acts as a semi-automatic leak detection system, obtaining data information to enable operators to take action before automation and/or safety system activation. It should be mentioned that a semi-automatic system means that the leak detection occurs automatically, resulting in an alarm signal in a continuously staffed control room. 

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) product line such as fiber Bragg grating sensors, FBG interrogators and multiplexers, Distributed Acoustic Sensing (DAS) systems, Distributed Temperature Sensing (DTS) systems. The company creates and supplies a broad variety of fiber optic solutions for monitoring worldwide. If you are interested in temperature measurement systems and want to learn more, please contact us at info@optromix.com

DTS performs dam monitoring

DTS for dam monitoringDams applied for hydropower, irrigation or mining play a crucial role in human life, herewith, they evoke significant human, economic, and environmental consequences when they fail. Nevertheless, distributed fiber optic sensing increases dam safety by offering early alerts of potential problems.

To be more precise, modern distributed sensing systems are considered to have high accuracy for monitoring promoting a continuous understanding of dam conditions, taking dam safety to a higher level. For instance,  distributed temperature sensing (DTS technology) uses high spatial resolution temperature data from distributed temperature sensors to record tiny seepage flow changes and to estimate seepage rates in a dam structure. 

It should be noted that seepage happens in most embankment and earth dams as the impounded water looks for the path of least resistance through the dam and its foundations. Therefore, excessive seepage presents a threat while high-tech sensing systems enable to detect and analyze subsurface processes and prevent erosion. Distributed fiber optic sensing is a promising technology that can be employed to control critical geophysical parameters, for instance, temperature and strain with a sub-meter resolution over several km. 

Additionally, distributed sensing systems provide the benefits of cost-effective high spatial monitoring coverage. The thing is that optical fiber acts as the sensing system along the full length of the fiber optic cable allowing operators to obtain detailed data information along the entire dam. Distributed temperature sensors can catch tiny, localized changes in the seepage flow rates that would otherwise remain unnoticed. “They deliver temperature readings with the accuracy of point sensors with the indisputable benefit of fiber optics: the highest possible spatial coverage. ”

Moreover, the distributed temperature sensing does not need specialized optical fibers resulting in relatively low-cost installation. The thing is that measurements based on DTS systems provide data along the entire dam with high spatial resolution and high-temperature precision. Herewith, distributed temperature sensors have already been used in tailings dams. One of the main elements of the increasing number of permanent tools is the ever-increasing performance of the DTS systems. Modern fiber optic sensing systems achieve the world’s most accurate measurements, with sampling resolutions of 12cm (over 5km) and with temperature resolution as low as 0.01 C.  

Finally, seepage detection used distributed temperature sensing is regarded as a crucial technology and has prominently improved the monitoring capabilities of dam operators. The application of optical fiber networks provides additional benefits like the ability of distributed sensing systems develops further.

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) product line such as fiber Bragg grating sensors, FBG interrogators and multiplexers, Distributed Acoustic Sensing (DAS) systems, Distributed Temperature Sensing (DTS) systems. The company creates and supplies a broad variety of fiber optic solutions for monitoring worldwide. If you are interested in temperature measurement systems and want to learn more, please contact us at info@optromix.com

Distributed temperature sensors promote warning systems

DTS for warning systemsTemperature is a key safety indicator in any industry. The technology of distributed temperature sensors using optical fiber allows measuring the temperature at any point in the fiber, with an interval of 1 meter, resulting in the detailed temperature dependence of all required areas. The data obtained by this technique makes it possible to develop intelligent warning systems based on it, therefore, replacing outdated point-based monitoring systems.

Operating principle of temperature sensors

The optical fiber itself acts like a fiber optic sensor, and the distributed nature of the DTS technology enables us to determine the temperature change at an arbitrary point, spreading many kilometers from it. Moreover, the measurement quality is not affected by electromagnetic radiation, thus, the distributed temperature technology is free from false alarms.

To be more precise, distributed temperature sensors (DTS) allow measuring the characteristics of an object along a fiber optic cable, while the fiber cable is a linear sensor, which is a continuously distributed sensing element throughout its entire length.

The operating principle is based on the reflectivity of stimulated Raman scattering of light (Raman effect). A semiconductor laser is also used to determine the location of temperature changes in a fiber optic cable. The fact is that the structure of the optical fiber changes when the temperature changes. 

When laser beam light from the laser system enters the area of temperature change, it interacts with the changed structure of the optical fiber, and in addition to direct light scattering, reflected light appears.

Benefits of temperature sensing systems

The main advantages of fiber optic sensors in comparison with classical analogs are the following:

  • Compact size;
  • Very fast response to parameter changes in the environment;
  • Low weight;
  • Multiple parameters can be registered simultaneously by a single distributed sensor;
  • Reliability;
  • Very wide operating temperature range of DTS;
  • Small price per unit length of the sensing system;
  • High sensitivity;
  • Long operating time;
  • The high spatial resolution of temperature sensors;
  • Resistance to chemicals and aggressive environments;
  • DTS is not affected by electromagnetic disturbances;
  • The sensitive part of the fiber sensor does not require connection to power lines.

The processing unit measures the propagation speed and power of both direct and reflected light and determines where the temperature changes. For instance, at a wavelength of 1550 nm, a pulsed generation mode is used with a laser power limit of 10 mW.

Types of sensors for temperature measurement

There are several types of optical fibers, each of which meets certain requirements for its properties, depending on the application due to the fact that the properties of the optical fiber can be varied over a wide range. 

Physical effects on the optical fiber, such as pressure, deformation, temperature change, affect the properties of the fiber at the point of exposure and it is possible to measure the environmental parameters by measuring the change in the properties of the fiber at a given point.

In general, a fiber optic sensor consists of two concentric layers: fiber core and optical coating. The fiber optic light guide part can be protected by a layer of acrylate, plastic, reinforced sheath, etc., depending on the application of this fiber cable.

Thus, distributed fiber optic sensors are perfect for industries related to combustible and explosive materials, such as coal, oil and gas production, etc. for use in fire alarm systems of various structures.

Common applications of DTS systems

Application of distributed temperature sensors includes:

  • fire alarm systems in the road, rail, or service tunnels;
  • thermal monitoring of power cables and overhead transmission lines to optimize production processes;
  • improving the efficiency of oil and gas wells;
  • ensuring the safe working condition of industrial induction melting furnaces;
  • monitoring the tightness of containers with liquefied natural gas on ships in unloading terminals;
  • detection of leaks in dams;
  • temperature control in chemical processes;
  • leak detection in pipelines.

In addition, DTS systems combined with other tools open completely new areas of application. For example, it is possible to design a specialized device – a fire detector based on a distributed fiber optic temperature sensor.

Temperature sensors for fire detection

Detecting a fire in an industrial environment is not an easy task because of the large number of disturbing factors, many of which can be considered by detectors as carriers of fire signs. In addition, dust deposited on the DTS‘ sensitive elements makes it difficult to operate and it can disable them.

It is also necessary to take into account the possible smoldering of the deposited dust, which can also lead to false alarms. The presence of fumes and aerosols makes it impossible to operate smoke optical-electronic fire detectors. The presence of carbon monoxide will trigger gas fire detectors.

Industrial facilities and production are characterized by large volumes of premises, high ceilings, the presence of long tunnels, collectors, mines, inaccessible areas, and premises with a complex configuration and geometry. And in these conditions, it is certainly possible to protect using traditional fire alarm systems, but this involves the use of a large number of detectors, and therefore they have high costs, including installation and maintenance of alarm systems and automation.

It is difficult to select detectors for explosive zones, especially for use in underground operations and mines. Aggressive media are often present in chemical industries. There are also objects of sea and river transport, characterized by the aggressive salt fog.

Oil and gas application

The use of non-electric sensing devices, the use of fiber optic cable allows the DTS to be applied in enterprises of the oil and gas complex, mines, underground operations, chemical industries (including those with aggressive environments), and metallurgy and energy enterprises.

As for oil companies, the active development of high-viscosity oil fields, which imposes strict requirements on the production equipment, and the severe depletion of most oil and gas fields require mining organizations to conduct prospecting and exploration operations, change production technologies and control the technical condition of wells.

The main task for mining companies to increase the well’s production capacity in real-time is to track information about the processes occurring in wells and fields. Solutions based on standard temperature sensors suggest well logging using point measuring instruments, which leads to the inaccuracy of the data obtained. 

The disadvantages of such sensing devices include the inability to fix the distribution of one of the most important parameters of the well – the temperature profile in real-time, as well as the need for power supply, the impact on the measurement results of external electromagnetic fields, labor and time costs required for the departure of the team and performing various operations, including the immersion of the fiber sensor element and its movement along the well, data processing, etc.

DTS as a part of a fiber optic system

The fiber optic sensing system consists of distributed temperature sensors designed to measure temperature along the borehole, and a point-to-point fiber pressure sensor. Optical fibers of a distributed temperature sensing system and pressure sensors can be structurally installed in a single fiber cable.

The fiber optic cable is resistant to mechanical damage. Additional fiber optic cable protection is not required during descent and lifting operations, but the protection of the fiber cable from mechanical damage during descent and lifting operations can be provided by the use of protective coatings.

Where to buy quality temperature sensors?

If you want to obtain a highly efficient distributed temperature sensing system, you should choose the Optromix company. Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for monitoring worldwide. Optromix is a fast-growing vendor of fiber Bragg grating (FBG) products line such as fiber Bragg grating sensors, FBG interrogators and multiplexers, distributed acoustic sensing (DAS) systems, distributed temperature sensing (DTS) systems. 

Distributed temperature system provides continuous underground power lines monitoring of temperatures, detecting hot spots, delivering operational status, condition assessment, and power circuit rating data. This helps operators to optimize the transmission and distribution networks, and reduce the cost of operation and capital.

Usually, the DTS systems can detect the temperature to a spatial resolution of 1 m with precision to within ±1°C at a resolution of 0.01°C. Measurement distances of greater than 30 km can be monitored and some specialized systems can provide even tighter spatial resolutions.
The advantages of working with Optromix:

  • Our DTS system has the superior quality, however, its price is one of the lowest in the market;
  • Optromix is ready to develop DTS systems based on customer’s specifications.

If you are interested in DTS systems and want to learn more, please contact us at info@optromix.com