Irina.Korneva@unicam.It

The quality of the carbonate deformed reservoir depends on the texture of the rock that determines connected primary porosity and on distribution and scaling properties of the discontinuities mainly represented by bedding, joints, veins, stylolites and fault zones [1,2,3]. As known, carbonate rocks are characterized by the development of wide deformation zones in which strain is distributed and zones in which deformation is adjusted by localized discrete structures such as fault zones. Therefore, the network of fractures in carbonates is characterized by the combination of diffused and localized deformation systems that defines the hydraulic properties of the carbonate reservoir [4].

With the aim to investigate the faults and fractures characteristics in tight platform carbonates, we analyzed fracture properties (i.e. orientation, spacing and opening) of both background (diffuse deformation) and fault-related deformation (localized deformation) in the Murge Plateau, southern Italy. The Murge Plateau represents the Plio-Pleistocene foreland of the South-Apennines orogenic belt which is characterized by a relatively-thick lithosphere and a little deformed sedimentary cover. The outcrops in Murge Plateau are good analogues of the Upper Cretaceous carbonate systems of the peri-Adriatic area that represent important hydrocarbon reservoirs in southern Italy [5]

Our results show that the cumulative frequency distributions of fractures spacing and opening are fitted by power-law, logarithmic or exponential relationships in agreement with different degree of faults development within the geo-structural contest of this sector of the Apenninic foreland. Moreover, based on the relative thickness between fault damage zones and fault cores, studied faults are characterized by different permeability structures [1, fig. 1]. These last parameters are strongly affected by the presence of both sedimentary dykes, which consist of large clasts of breccias, clay material and calcite, and karst that often are present within the fault damage zones.

Collected data about fractures and faults distribution and its dimensional properties allow us to recognize the structural control on geofluid migration and possible paths of geofluids and provide a good base for constructing Discrete Feature Network (DFN) models of fractured carbonate reservoirs [6].

References:

1. Caine, J. S., Evans, J. P., Foster. C. B. Fault zone architecture and permeability structure // Geology. 1996. V. 18. pp. 1025-1028.

2. Agosta, F., Alessandroni, M., Antonellini, M., Tondi, E., Giorgioni, M.. From fractures to flow: a field-based quantitative analysis of an outcropping carbonate reservoir. Tectonophysics, 2010, 490, 197-213.

3. Tondi, E., Cilona, A., Agosta, F., Aydin, A., Rustichelli, A., Renda, P., Giunta, G. Growth processes, dimensional parameters and scaling relationships of two conjugate sets of compactive shear bands in porous carbonate grainstones, favignana island, Italy, Journal of Structural

Geology (2012), doi: 10.1016/j.jsg.2012.02.003.

4. Aydin. A. Fractures, faults and hydrocarbon entrapment, migration and flow // Journal of Structural Geology. 2000. V. 22. Issue 1. pp. 1-23.

5. Lentini F., Catalano S., Carbone S. The external thrust system in southern Italy; a target for petroleum exploration // Petroleum Geoscience. 2008. Vol 2, No 4, pp. 333 - 342.

6. Dershowitz, W., P. LaPointe, H.H. Einstein, and V. Ivanova, 1997. Fractured Reservoir Discrete Feature Network Technologies. Quarterly progress reports, prepared for contract G4S51728, US Department of Energy, National Oil and Related Programs, BDM-Oklahoma.