Natural fractures distribution in mixed facies: A geomechanical model for heterogeneous reservoirs (Quintuco Formation, Neuquén basin)

The distribution of natural fractures in mixed carbonate-siliciclastic reservoirs has a critical influence on fluid flow and reservoir performance. Internal sedimentary and structural heterogeneities represented by facies characteristics, bedding thickness, and fracture networks significantly affect petrophysical parameters. In low permeability reservoirs, fractures enhance fluid flow. Their distribution depends on stress orientation, magnitude, and rock competence, varying with the properties of the sedimentary layer.This study analyse the spatial variability of natural fracture networks within the reservoir heterogeneities using geomechanical facies. It identifies non-competent facies with low fracture intensity and competent facies with high fracture intensity, in order to improve predictions of reservoir behaivour. The research focuses on the Lower and Middle Members of the Quintuco Formation (Loma La Lata Block, Neuqu´en Basin), a heterogeneous reservoir characterised by stratigraphic and structural trapping mechanisms and a developed fracture system, and its surface equivalent, the Picún Leufú Formation (Tithonian-Berriasian).Data collection involved scratch tests and facies analysis supported by detailed sedimentological sections from three core-wells, which were correlated with Gamma Ray logging and X-ray diffraction analyses. Three geomechanical facies were identified: High Resistance-Competent, Low Resistance-Competent, and Non-Competent facies. This work reveals that systematic fractures developed at mechanical contrast interfaces exhibited increased fracture intensity and connectivity, with porosity reaching up to 10%, thereby enhancing the fluid transport. Integrating multi-scale analyses enhances the geomechanical modelling and identifies areas with greater permeability. This work contributes to refining predictive models for exploration and defining development strategies for heterogeneous reservoirs, aiming to optimise the drilling production by targeting highconnectivity zones. Fil: Tettamanti, Magdalena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; Argentina Fil: García, Micaela Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; Argentina