Perfect: Extreme conditions for drilling test Research drilling on Lake Constance successfully completed
From mid-May to mid-July 2019, four drilling experts on the newly developed “HIPERCORIG” platform took lake sediment samples from over 200 metres water depth on Lake Constance, Germany. In addition to researchers from the Technische Universität Braunschweig and the University of Konstanz, students from Braunschweig, Bern and Bochum were also involved. Their goal was to test the new drilling system and to retrieve continuous lake sediment cores and sample sediments. Two core sections, 24 and 22 metres long, respectively – more than twice as long as previously possible – were recovered in this way two kilometres southwest of Hagnau. The technology could also be improved considerably.
Great challenges on site were the great depth of the water, strong water currents and sandy sediment layers instead of fine clays. In addition, there were violent thunderstorms with heavy rainfall and a local storm that caused the lake level to swell by one meter. As a result, an anchor came loose, the platform shifted slightly and finally the casing of the borehole tore off.
Hardness test
These extreme conditions served as a hardness test of the drilling system, which was immediately adapted to meet demands. The sandy sediments were countered by an improved drilling and flushing technique until finally single 2-m-sediment cores were retrieved from the lake floor every hour. The offset of the platform could be corrected with the help of the cameras of a diving robot of the Institut für Seenforschung of the Landesanstalt für Umwelt Baden-Württemberg. The guiding elements at the bottom of the lake, which are part of the drilling system, were also rebuilt so that they could insert the drill string better.
In addition, new winches and safer lifting tools will prevent the loss of drilling equipment, which caused considerable time losses during the test on Lake Constance. All in all, the drilling campaign was the perfect test: “Many lessons were learnt, and it was bitten through according to the motto: ‘Better now on Lake Constance than during subsequent operations at the other end of the world’,” says Professor Antje Schwalb from Technische Universität Braunschweig.
Platform as a turning buoy
The work on Lake Constance was accompanied by residents and water sports enthusiasts with great interest and curiosity. Some sailors used the platform as a turning buoy. Special thanks go to the mayor Frede and harbor master Müller in Hagnau, harbor master Willer of Hagnau-West, Mr. Burger from the district office Landratsamt Bodenseekreis, the Wissenschaftliche Werkstätten of the University of Konstanz and the Institut für Seenforschung for the very informative and helpful use of the research vessel “Kormoran” with diving robot.
Next steps
The course of the test now also allows the operating costs to be realistically recorded, making cost estimates for future applications possible. “HIPERCORIG” is now given the final touches by its manufacturer in Mondsee. The coring system will then be stored at the International Geothermal Centre (GZB) at Hochschule Bochum – Bochum University of Applied Sciences. A call for drilling proposals using the device will be published shortly. Then “HIPERCORIG” can also be transported worldwide to locations in regions with poor access.
After initial sampling at the University of Konstanz with regard to volatile and biologically sensitive components, the sediment cores are accommodated at the University of Bern. There, in October 2019, further joint sampling, the so-called “Core Sampling Party”, will take place, in which a total of eleven institutions will be involved. Now the research can begin!