Reconstruction of a "Discrete Fracture Network" in the geothermal reservoir of Rosario de La Frontera (La Candelaria Ridge, Salta province, NW Argentina)

MAFFUCCI ROBERTA; BIGI SABINA; CHIODI AGOSTINA; CORRADO SVEVA; DI PAOLO LEA; GIORDANO GUIDO

Pisa

Congreso; European Geohtermal Congress 2013; 2013

In this contribution we present and discuss the reconstruction of a Discrete Fracture Network model of the reservoir of the geothermal system of Rosario de La Frontera, located in Salta province (NW Argentina). This model allows to assess the effective permeability of the reservoir and to obtain input parameters for dynamic reservoir modelling. Structural studies performed on the outcropping portion of the reservoir, allowed us to define the main fracture system occurring in the structure and to calculate the input parameters for the generation of the DFN in a 3-D volume of the buried geothermal reservoir, using dedicated software (e.g. Move by Midland Valley Ldt.). Faults and fractures were analyzed and quantified by means of scan-lines and scan-area surveys defining diagnostic parameters such as fracture type, orientation, dimension, surface texture and numerical parameters (e.g., density and spacing, length, aperture, etc.). According to the orientation data, the observed discontinuities have been classified in different sets interpreted with respect to the regional structural setting and their density distribution was assessed in different sectors of the reservoir. In conclusion, several DFN models were generated, one for each fracture set. Furthermore, comparison among the different models provided a preliminary qualitative assessment of reservoir permeability with special regard to the anisotropy due to the secondary permeability.