IMAGE-D8.02: Application of exploration techniques on sedimentary basin fields

This report details the application of exploration techniques (task 8.02) developped in the WP7 and applied on the sites selected following the task 6.02 (IMAGE deliverable D6.02). In this previous task, we defined three targets : the Upper Rhine Graben as a brown site or test site, where a solid experience with standard exploration tools and databases exist, the Molasse Basin and the Lower Rhine graben, as green sites ou new sites, where the geothermal exploration is on-going. 

In the Upper Rhine Graben, geophysical tests have been done in the area of Strasbourg, where some geothermal operations are planned managed by FONROCHE Geothermie and ES-G. On this area, a passive seismic network has been deployed in order to test the data acquisition in a noisy environment (close to a large town). This data have been used as two approaches: a joint inversion of group speed of Rayleigh waves obtained through long-range noise correlation and H/V curves associated with the main site effect, and a computation of receiver functions from teleseismic events recorded in a urban area. The aim of these approaches is to precise the depth of sediment-basement interface, which is not reach by the older seismic profile acquired by the oil industry (because it was not the target for the petroleum reservoir). On the exactly the same area, a electromagnetic survey has been done, included a CSEM (Controlled Source ElectroMagnetism) acquisition. 

A systematic analysis of the fractal properties of the deep geothermal reservoirs of Basel and Soultz has been performed in order to investigate the scaling relationships of natural fracture, stress and induced seismicity. 

In the Molasse Bassin, two sites have been investigated. First, in Switzerland, near Geneva, an old geothermal well has been used to test an acquisition of Vertical Seismic Profile (VSP) and analyse the geochemistry of the fluid. These works were performed with the industrial owner of the weel, SIG (Service Industriel de Genève), who forecast to reuse this well. In the German part of the Molasse Basin, the town of Bal Waldsee is planning a geothermal system and acquired local vintage 2D seismic data from oil and gas companies. In order to better analyse these data, a new NLM (Non Local Means) reprocessing was applied and compared to the classical pre-stack seismic reprocessing. 

A another passive seismic survey was done in the Grote Peel area in The Netherlands with the purpose to retrieve surface waves from ambient noise.