Structural analyses and fracture network characterisation: Seven pillars of wisdom

Seven distinct types of structural analysis can be defined, each with their own data and uses: (1) basic geological descriptions; (2) geometries and topology; (3) age relationships; (4) kinematics; (5) tectonics; (6) mechanics and (7) fluid flow. We illustrate these types of analysis using the example of faults and fractures, which typically form networks of interacting and connected segments. A framework for describing and characterising fault and fracture networks is presented for each of the structural analysis types. We suggest that any structural study be tailored to suit the desired outcome and that this scheme of analysis types should be used as a basis for the development of workflows, for the design of research projects and for testing hypotheses. For example, prediction of fluid flow through a fracture network must begin with the basic geological description of fracture types. Basic geological descriptions should be followed by measuring their geometries and topologies, understanding their age relationships, kinematic and mechanics, and developing a realistic, data-led model for related fluid flow. Missing steps can lead to fundamentally flawed interpretations.