Calcimetry as a useful tool for a better knowledge of flow pathways in the Soultz-sous-Forêts Enhanced Geothermal System

摘要: The Soultz-sous-Forets granite located in the Rhine graben (France) has been chosen for European Enhanced Geothermal System (EGS). Three wells have drilled to a minimum depth of 5000 m order reach temperature 200 °C. At Soultz, main fracture network basement is orientated approximately N–S with moderate steep dip. Its geometrical relationship situ stress field suits fluid circulation, hence EGS project. However, fractures are firmly sealed due natural fluids (fossil and/or possibly present). sealing minerals, as identified during previous studies, clay calcite and quartz. some fractured zones remain permeable high porosity developed wall rocks through hydrothermal alteration. A circulation test was carried out from July December 2005 performance Soultz geothermal reservoir. This showed significant difference production rate between two outflow (GPK2 GPK4). In improve within underground heat exchanger, chemical stimulations scheduled. this framework, quantifying content provides basis identifying calcite-rich well choosing most suitable stimulation. Measurement ponderal concentration cutting samples 3 deep (GPK2, GPK3, GPK4) 4000 using manocalcimetry. Based on detailed measurements wells, study shows that not only very common ubiquitous mineral but its seems be also spatially correlated bearing flow. conductivity these flow pathways anti-correlated content. Calcimetry proved an easy, efficient low-cost method better knowledge can applied great benefit all types reservoirs (oil, gas, water, heat) overlain by sedimentary understanding permeability.