Petrophysical characterization of Triassic and basement formations for geothermal purposes in the Paris basin: from sub-surface data to reservoir outcrop analogue

A coupled study on deep cores from the Paris basin brings new insights for the geothermal potential of the area on both sedimentary and basement geological units. Petrophysical and petrographic results of continental successions from Upper Triassic formations show that the western edge of the Paris basin can deliver fairly good reservoir properties (5-23% porosity and 5-800 mD permeability) with a the best quality index found in fluvial facies types along the continental deposition profile. The burial of the sedimentary sequence affects the reservoir quality with appearance of several diagenetic phases (dolomite and calcite cements) and feldspar dissolution to a lesser degree. In parallel, an analytical work is conducted on basement rocks from deep cores and combines petrography and petrophysics for identifying potential structures for hot water circulation in the Variscan basement, displaying mineralogical testimonies of paleofluids. These targets in the Paris basin are part of a broad scale European project called MEET, for Multidisciplinary and multi-context demonstration of EGS exploration and Exploitation Techniques and potentials. This project aims to increase the geothermal market at European scale by means of original exploitation techniques and the identification of untapped geothermal resources of various geological contexts of Europe.