Role of the Inherited Structure and the Paleo-Weathered Surfaces on the Reservoir Quality Within the Basement

Abstract

Rifting zones and passive margins are two main extensive geodynamical domains where heat fluxes could be attended to be high and may be prospection targets for high enthalpy fluid production. Through the description of structures composing the network that control fluid flow at different scales, different models of reservoirs can be proposed with respect to rift or margin geometries. In these settings, large-scale porous networks consists faults, fracture networks and weathered horizons at the cover-basement interfaces. Their relationships and their shapes depend on the geodynamical context and the intensity of extension that could control the conservation of the weathered facies. The role of the inherited structures from the previous geological history on the reservoir development and on their transfer properties is also discussed. One example located in the eastern African rift system is presented here. In this case, a long geological history, with petrographic and structural heterogeneities, contributes to the reservoirs’ structures, and controls its quality.