Underwater streamer

Research on submarine sedimentary horizons has gained steadily in importance in recent years. Information on the structure and composition of sediments is required for coastal research, the further development of marine shipping lanes, as well as for the industrial laying of submarine cables. The specific electrical resistance is the key parameter for identifying the different types of sediment. In co-operation with Geoserve, the institute developed a surveying system specially for use in shallow coastal locations.

The University of Greifswald supports the project with its research vessel FS Bonhöft, and its detailed geological understanding of the Baltic coast. The system was further refined during several research cruises. It also helped the equipment to be adapted to the rough surveying conditions in salt water. 

The heart of the system is a RESECS tool with an underwater streamer to record specific electrical resistance. The streamer has 26 electrodes with a maximum electrode separation of 48 m. The 8-channel RESECS tool records two surveying cycles in a Schlumberger arrangement measured either normally or inversely. These two cycles require approx. 1 s to record one Schlumberger log.

Another component is the specially developed logging system which uses a data logger and various sensors to record the depth (pressure sensor), conductivity (LF tool), temperature and GPS data in continuous measurement mode. The data is stored on a CF card at a sampling rate of approx. 1 s and an amplitude resolution of 16 Bit. Data can be exported to other programs when surveying is finished. The data can be displayed in real time on the display during surveying to enable the streamer to be run at the required depth.