Title: Ternary fault permeability diagram: An innovative way to estimate fault zones hydraulics
Abstract: Understanding the impact of fault zones on reservoir trap properties is a major challenge for a variety of geological resources applications. Fault zones in cohesive rocks are complex structures, composed of 3 components: rock matrix, damage zone fractures and fault core rock. Despite the diversity of methods to estimate fault zone permeability/drain properties, up to date none of them integrate simultaneously all three components, nor their evolution with time. In this paper, we present a ternary plot that characterizes the fault zones permeability as well as the drainage properties. The ternary plot aims at characterizing the fault zone permeability between the three vertices (matrix, fractures and fault core permeability) and at defining the drain properties among 4 possible hydraulic systems: (I) good horizontal and vertical, fault-perpendicular and -parallel; (II) moderate parallel fluid pathway; (III) good parallel fault-core and (IV) good parallel fractures. The ternary plot method is valid for 3 or 2 components fault zones. The application to the Castellas Fault field case study (SE France) shows the simplicity and efficiency of the plot for studying underground as well as cropping out active and/or fossil, simple or polyphase faults in reservoirs with complete or limited permeability data.