Reservoir Sedimentology, mineralogy and chemostratigraphy of a Permo - Carboniferous through infill in NE Switzerland. Implication for geoenergy exploration

This work re–examines from a sedimentological, mineralogical and geochemical prospective the Permo – Carboniferous infill of a core drilled in the northern part of the Swiss Molasse Basin: the Weiach core. While previously published reconstructions suggest the presence of an anastomosing fluvial system dominating the Carboniferous portion, this work proposes, on the account of the observed facies assemblage, a new depositional environment represented by a delta front prograding periodically into a lacustrine system. A new interpretation is presented also for the Permian domain; a lake dominates all over the Permo – Carboniferous transition and, subsequently, an alluvial mud flat characterized by irregularly alternated stage of exposure and flooding takes over the area. Remarkably the grain size increment, caused by hyperconcentrated flows arriving in the area triggered by tectonic adjustments. Moreover, in order to evaluate the association of geothermal hot aquifer systems with hydrocarbon occurrence in the study area, multiple analytical procedures, e.g., QEMSCAN, SEM, XRD and XRF, were used and integrated with powerful software results, e.g., PETREL, demonstrating that in the Carboniferous sandstone there still could be exploitable amount of thermogenic gas.