Fractured Crystalline Reservoir: a Field Analog Analysis on Tamariu’s Granite (Catalonian Coastal Ranges)

Tamariu’s granite has been studied with the aim to characterize the fracture network and the porosity through the analysis of cementation associated to paleo-fluids circulation. With the help of regional and outcrop studies (Le Garzic 2010, Place 2010), we could interest on the fracture network over 8 orders of magnitudes. We used 1D scan lines and 2D fracture mapping on outcrop pictures to precisely define the fracture network and the organization of the flow in this network. The data acquired on our maps show a power law distribution of the cumulative fractures numbers and faults lengths between the centimeter scale and the hundred kilometers scale. This homogenous length distribution over a large range of scales contrasts with the fracture orientation distribution that highly depends on the scale observation and on their location relative to the larger structures. The volume of paleo-fluids associated cementation has been quantified using calcimetry and mapping of different parts of the porous network: the veins, breccias cemented by carbonates, fractured granite and poorly fractured granite. The percentage of percolated rock volume reaches to 3% of the total granitic body, and the main part of them are localized in fractured corridors composed of mains veins and breccias.