DAS - Distributed Acoustic Sensing

The use of fiber technology is rapidly evolving, and at NORSAR, we leverage our extensive expertise in vibration detection and seismic monitoring to explore and develop applications beneficial to society.

Fiber optics offer a diverse set of application possibilities, including microseismic monitoring, pipeline and cable monitoring, border control and security applications, and railway and highway monitoring. NORSAR primarily utilizes Distributed Acoustic Sensing (DAS) technology, which uses fiber optic cables—either existing telecom cables or more specialized ones. The system includes an interrogator that uses laser light to detect minute vibrations in the fiber optic cable. These measurements provide continuous and precise localization of vibrations along the entire length of the cable, with a measurement density down to one meter over a stretch of up to 150 kilometers. Using edge computing and automated processing, we can handle large amounts of data and set up automated processing and alarm systems.

The approach is not new: DAS technology has been used to monitor pipelines in the petroleum industry for over 10 years. However, despite being well-established in this sector, there are significant differences in pipelines, contents, and pressure contexts, necessitating further development of the existing technology to be applied in other areas. NORSAR is testing possibilities and developing solutions for using DAS technology in several areas. We also offer access to state-of-the-art fiber optic infrastructure.

Automated snow avalanche detection and traffic monitoring

Avalanche warning is one of the areas where this technology is now being applied. Avalanches pose a significant societal challenge both in Norway and other parts of the world. NORSAR and our partners have developed a snow avalanche monitoring solution based on fiber optic cables embedded in roads. The system detects if a snow avalanche hits the road and if any vehicles are in the avalanche area. This information can then be used to close the road and avoid further traffic. The system was tested in Holmbuktura in Troms, with pilot tests conducted between December 2022 and January 2023. These tests demonstrated that the fiber system reliably detects avalanches hitting the road, reducing false alarms by 94%. Furthermore, automatic detection algorithms can identify vehicles and categorize them by type, quantity, velocity, and direction, all without the need for images to ensure privacy compliance. Solutions for traffic monitoring and snow avalanche monitoring are under commercialization.

 

 

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Water Leaks

Norway is among the countries in Europe with the highest percentage of drinking water lost during transport from source to consumer, averaging around 30% according to Statistics Norway (SSB). The cost to society is significant. NORSAR is testing the use of DAS for detecting leaks in low-pressure water pipelines. In collaboration with Hallingplast, NORSAR has established a full-scale test facility in Ål, Hallingdal, to develop and test methods for detecting leaks in water pipes. Additionally, extensive tests of the technology have been conducted in cooperation with IVAR (Inter-Municipal Water, Wastewater, and Waste Management) in Rogaland and also through the research project LeakNor.

Tests have also been carried out on the existing municipal pipeline network in places such as Lillestrøm. The results are promising.

Fiberoptic infrastructure

NORSAR provides unique opportunities for testing fiber technology, ranging from instruments and calibration sites to full-scale monitoring test facilities. Each component utilizes state-of-the-art equipment. The infrastructure is a part of the Norwegian national infrastructure and is open for external users.

NOR-FROST is located on our premises at Kjeller and consists of three parallel trenches, each 30 meters long and 1 meter deep, filled with concrete, gravel, and sand respectively. Various fiber cables from different vendors are laid at three different depths in each trench. This setup supports three core research areas within fiber sensing technology: Distributed Acoustic Sensing (DAS), Distributed Strain Sensing (DSS), and Distributed Temperature Sensing (DTS). The test site allows for the comparison of cables, interrogators, and recording parameters in a controlled environment with easy access.

NOR-FROST

NOR-FROST

NORFOX is a full-scale fiber-optic array located in southeast Norway. Its innovative design comprises five arms radiating from a central point, each approximately 1750 meters long and equipped with two cables, totaling six standard telecom fibers and two enhanced fibers. This array is co-located with the NORES seismometer array, enabling research on the seismological detection capabilities of fiber sensing installations, both in classical and array configurations. Additionally, it facilitates fundamental research on fiber technology, including DAS and DTSS (Distributed Temperature and Strain Sensing), with unique opportunities for DAS signal calibration.

NOR-DIP (Distributed Sensing Instrument Pool) provides fiber sensing equipment to interested organizations. It includes two ASN-OptoDAS interrogators for acoustic sensing and one NKT-LIOS DTSS for temperature and strain measurements. Fiber splicing and inspection tools are also available, with all equipment supplied in field-ready transport cases. Technical support is available upon request.

The fiberoptic infrastructure is part of the European research infrastructure ECCEL ERIC and is funded by the Research Council of Norway.