From Fracture Analysis to Flow Simulations of an Outcropping Hydrocarbon Reservoir (The Roman Valley Quarry, Majella Mountain)

The Roman Valley Quarry located at the northern termination of the Majella anticline in central Italy contains an excellent exposure of bitumen-bearing faulted carbonates, and therefore provides the opportunity to assess the role of stratigraphic and structural heteroge-neities on subsurface flow. The vertical walls of this quarry expose in 3D the inner structure of two oblique-slip normal faults oriented WNW-ESE (called the SW and NE Faults). These faults crosscut the Oligo-Miocene Bolognano Formation, which is a medium- to high-porosity limestone (Cilona et al., 2014)2. The SW Fault has a seismically detectable throw of 40 m, and consists of a continuous main slip surface, with fault rocks that vary along strike from clast- and cement-supported cataclastic rock to un-cemented breccia. This fault be-haves as both a conduit and barrier for fluid flow. Conversely, the NE Fault, which has a sub-seismic throw of 8 m, consists of a fractured zone where several smaller slip panels in-teract, forming a distributed conduit permeability structure (Agosta et al., 2010)1. Laboratory measurements and detailed Discrete Fracture Network (DFN) models are in-tegrated to quantify matrix and fracture contribution to porosity and permeability within each of the lithofacies cropping out in the study area. DFN models were constrained by spa-tial and dimensional properties of fractures obtained by scanline surveys. These models were used to calculate fracture permeability and porosity based on the Oda upscaling meth-od. Finally, the obtained hydraulic properties were used to build an outcrop-scale static model of both the matrix and the fractures. This model is useful to build flow simulations to test fluid pathways for various flow scenarios showing the role played by the stratigraphic and structural heterogeneities. Reference: 1) Agosta, F., Alessandroni, M., Antonellini, M., Tondi, E., Giorgioni, M. 2010. From fractures to flow: A field-based quantitative analysis of an outcropping carbonate reservoir. Tectonophysics 490, 197–213. 2) Cilona, A., Faulkner, D. R., Tondi, E., Agosta, F., Mancini, L., Rustichelli, A., Baud, P., Vinciguerra, S. 2014. The effects of rock heterogeneity on compaction localization in porous carbonates. Journal of Structural Geology, 67, 75-93.