Dolostones in a Neogene strike-slip fault zone are described. Two main types of structural features are recognised: (i) Background deformation in the form of a network of bedding-perpendicular and hybrid conjugate fractures, barren fractures and bedding-parallel stylolites. (ii) Fault-related features include breccias and cataclasites. Orthorhombic rock lithons are generated from the intersection of fracture sets with bedding and/or joints. Lithon size and morphology change across the dolostone fault block gradually producing a tetragonal or isometric shape. The lithons are 1–2 cm in dimension (only ~ 20% outside this range) and have an average cross-sectional aspect ratio of 1.6, irrespective of size or structural position. Topology is analysed using nodes and branches, ranging from isolated (I- node and I-I branch) to connected (Y- and X-nodes, and I-C to C-C branches) respectively. The quantitative description of the geometrical and topological analysis of the dolostone lithons suggest that they become more connected and interact within the dolostone fault blocks. Assessing the change in topology and lithons connectivity have important implications for subsurface reservoirs and aquifers hosted in dolostone-fault zones.

A high-resolution three-dimensional (3D) outcrop model of a Jurassic carbonate ramp was used in order to perform a series of detailed and systematic flow simulations. The aim of this study was to test the impact of small- and large-scale geological features on reservoir performance and oil recovery. The digital outcrop model contains a wide range of sedimentological, diagenetic and structural features, including discontinuity surfaces, shoal bodies, mud mounds, oyster bioherms and fractures. Flow simulations are performed for numerical well testing and secondary oil recovery. Numerical well testing enables synthetic but systematic pressure responses to be generated for different geological features observed in the outcrops. This allows us to assess and rank the relative impact of specific geological features on reservoir performance. The outcome documents that, owing to the realistic representation of matrix heterogeneity, most diagenetic and structural features cannot be linked to a unique pressure signature. Instead, reservoir performance is controlled by subseismic faults and oyster bioherms acting as thief zones. Numerical simulations of secondary recovery processes reveal strong channelling of fluid flow into high-permeability layers as the primary control for oil recovery. However, appropriate reservoir-engineering solutions, such as optimizing well placement and injection fluid, can reduce channelling and increase oil recovery.