Pipelines: Berlin Brine Pipeline

Case study: DiTeSt System

Pipeline temperature and leakage monitoring
Remote continuous operation

Project Description

Summary: Continuous temperature and leakage monitoring of brine pipeline 55 km long using two DiTeSt reading units and four optical fibre cables installed below the pipeline.

Clients: GESO

Place: Surrounding of Berlin (Germany)

Period: 2002 - 2005

Installation: GESO/Omnisens/SMARTEC

Structure's short description: In 2002 the construction of a natural gas storage facility some 1500m under the ground surface was started in the area of Berlin in Germany. Using mining technology the building of underground caverns for gas storage in large rock-salt formation requires hot water and produces large quantities of water saturated with salt, the so-called brine. In most cases the brine cannot be processed on-site and must be transported by a pipeline to the location where it can either be used for chemical processes, or injected back safely into the ground. Because the brine can be harmful for the environment, the pipeline shall be monitored by a leakage detection system. In the Berlin project a 55km pipeline was built.

Aim of monitoring: In order to cover the whole pipeline distance, it was decided to use two DiTeSt analyzers although one instrument would have been theoretically able to cover the whole distance with its two channels. However the installation of the fiber cable required some 60 splices (that correspond to a additional loss of up to3 dB) which reduces the distance range of the instrument accordingly and justified the use of two instruments. The selected sensing cable is a customized version of a standard armored telecommunication fiber optics cable for underground applications. The cable includes the optical fibers used for temperature monitoring as well as fibers for data communication between the instruments and the control room and additional spare fibers. During the construction phase the fiber cable was first placed in the trench and buried in the sand some 10 cm underneath the pipeline. The position of the cable with respect to the pipeline is important in order to guarantee that all leakages are detected. The position of the sensing cable is a trade-off between the maximum contrast in the case of a leakage and the assurance to detect leakages occurring from every point of the tube circumference. Both DiTeSt instruments are installed in dedicated buildings (gate II and gate V respectively). Each instrument is responsible for the monitoring of half of the total distance and an optical switch is used to select the section to be monitored, so that the longest fiber section is 16,85 km. The central computer located in the control room in R?ersdorf can communicate with the instrument through an optical LAN that makes use of available fibers of the sensing cable. The temperature profiles measured by both DiTeSt instruments are transferred every 30 minutes to the central PC and further processed for leakage detection.

Number of sensor: 4

Main Results: The pipeline construction phase was completed in November 2002 and the pipeline was put into operation in January 2003. In July 2003, a first leakage was detected by the monitoring system. It was later found that the leakage was accidentally caused by excavation work in the vicinity of the pipeline.

Both DiTeSt instruments have two measurement channels, respectively called sensor 1 to 4. The sensors temperature profiles are periodically transferred to the central PC for further processing and alarm generation.

Configuration of the rack integrating the DiTeSt analyzer together with dedicated UPS and cooling system. An optical Ethernet is used for the communication between the instruments and the central PC in the control room.

Construction phase of a buried brine pipeline in the north-east area of Berlin. The fiber optics cable is placed in the sand at the 6 o?clock position about 10 cm underneath the pipeline.

Measured profiles before and after the leakage occurred at distance 17?970 meter from the pumping station, as displayed on the central PC in the control room.

Bibliography:

Leakage detection using fiber optics distributed temperature monitoring , M. Nikl?, B. Vogel, F. Briffod, S., F. Sauser, S. Luebbecke, A. Bals, Th. Pfeiffer, 11th SPIE's Annual International Symposium on Smart Structures and Materials, March 14-18, 2004, San Diego, USA, Vol. 5384, 2004

Long-Range Pipeline Monitoring By Distributed Fiber Optic Sensing , D. Inaudi, B. Glisic, 6th International Pipeline Conference September 25 - 29, 2006, Calgary, Alberta, Canada, 2006

Fibre Optic Methods for Structural Health Monitoring , Branko Glisic and Daniele Inaudi, Johh Wiley & Sons, Ltd, 2007