The Use of Outcrop Analogue Basement Rocks to Help Seismic Imaging of Buried Reservoirs

Basement rocks are well studied nowadays for their exploitation as geothermal reservoirs or for mineral exploration. In these rocks, the matrix permeability is poor and the fluid flow (geothermal resource or linked to mineral precipitation) is mainly controlled by the natural fracture and fault network and associated weathered materials. Unconfortunately, the fracture and fault pattern at reservoir scale in the basement is not well known and is difficult to characterize with the actual geophysical tools. The use of analogue rocks at the outcrop is therefore an important tool for helping to the reservoir characterization. This study present a synthesis of basement outcrops studies in different geological setting linked to crustal extension. The method used was to combine satellite pictures, field studies and laboratory measurement in order to define the faults, fractures and cracks network at the largest range of scales as possible. That have lead us to construct a reservoir’s model composed by blocks of different orders depending on their size bounded themselves by faults with decreasing thickness and lengths. This model is a key tool for the characterisation of fractured buried reservoirs by seismic imaging.