FLUID STORAGE AND CIRCULATION IN CARBONATES: A SILURIAN CASE STUDY IN EASTERN CANADA

Geothermal energy resources are now being developed in non-magmatic areas, particularly in sedimentary basins. In such contexts, geothermal energy can be produced locally, near consumers, as individual or industrial heat production facility from deep water well. Conventional methods applied to oil and gas reservoirs are revisited in the present project to address fluid flow and fluid storage capacity in carbonates for a Silurian succession in eastern Quebec considered a potential geothermal target. The Sayabec Formation is a Silurian carbonate formation with naturally and macro porous intervals, well-known at the outcrop scale and interpreted as hydrothermal in origin. In addition, bioturbated facies within the Sayabec Formation are abundant and microporosity might play a key role in connecting the macropores. For those reasons, the Sayabec Formation represents a good reservoir analog of the Albion-Scipio oil (Ordovician, Michigan basin, USA) or the Ladyfern gas (Devonian, British Columbia) fields. A local oil and gas operator has demonstrated its interest in the area by drilling about 6000 meters of stratigraphic wells over the past ten years. With this case study, research activities compile key geological attributes and reconstruct the timing of diagenetic fluids circulation creating or occluding porosity. The dataset in the area includes surface field observations to define stratigraphy, core logging from five different wells used for facies analysis, conventional, fluorescence, and cathodoluminescence petrography of 110 thin sections, stable isotopes analyses, conventional petrophysics to determine porosity and permeability, and thermal conductivity analysis. In addition, an in-house core flooding set-up has been used to evaluate large-scale porosity profile (plurimetric) using a medical CT-scan. Two main potential reservoir geobodies are considered: fractured and hydrothermally altered units and bioturbated units. The main goal is to understand how a conventional reservoir characterization can applied to develop geothermal direct use in a low temperature environment.