Producción CyT
Acta resumenes AAPG ICE 2025 - Natural Fracture Events in the Quintuco Reservoir, Neuquén Basin, Argentina
Congress
Autoría:
Tettamanti, Magdalena ; GARCÍA, MICAELA ROMINA ; Franzese, Juan R. ; Muñoz, Tobias ; Gómez Peral, Lucia ; Poiré, DanielFecha:
2025Editorial y Lugar de Edición:
AAPGResumen *
The internal heterogeneities of mixed carbonate-siliciclastic reservoirs involve spatial variability in permeability, significantly influenced by factors such as natural fractures (NF). NF networks play a critical role in heterogeneous reservoirs with low-hydraulic properties, as they can enhance or hinder fluid flow thereby impacting hydrocarbon (HC) productivity. Modelling these NF networks is particularly relevant for optimizing HC recovery in such reservoirs. This study aims to analyse the geometric characteristics, fillings, and deformation timing of NF associated with fluid migration in heterogeneous reservoirs, focusing on the Quintuco Formation within the Neuquén Basin (NB).The NB one of the largest HC-producing basins in South America, is located east of the Andean Cordillera, Argentina. The Quintuco Formation (Tithonian–Valanginian) constitutes a key reservoir characterized by stratigraphic and structural trapping mechanisms and an extensive NF system. This unit is present in the subsurface at the eastern sector of the NB, within the Neuquén Embayment (NqE). The lower to middle sections of the Quintuco Formation correlate with the Picún Leufú Formation (Tithonian-Berriasian) in outcrops of the Agrio Fold and Thrust Belt (AFTB) to the west. This stratigraphic interval also shows low permeability facies, characterized by the occurrence of NF that enables the hydraulic conductivity To characterise the NF system, systematic data collection was carried out using scanlines and sampling from subsurface cores in the NqE and outcrops in the AFTB. The AFTB samples were analysed using an optical microscope to examine their fracture fillings, and stable isotope analysis (δ13C and δ18O) of calcite infillings were performed to determine the crystallization temperature. The results indicate that the reservoir’s fracture system consists of three types: (I) non-tectonic fractures (stylolites and compaction bands; NTF), (II) tectonic fractures (TF; S1, S2, S3 in outcrops; STF in subsurface) and (III) overpressure fractures (bed parallel or vertical veins; OF1 and OF2), found only in cores. Crosscutting relationships indicate that NTF are intersected by TF, OF1 and OF2. Stable isotope analysis in TF of AFTB shows that the S1 (NNE) calcite fillings crystallized at 211°C, while S2 (WNW and ENE) ranges between 150-163°C, and S3 (NE) ranges between 128°-137°C. Based on the reinterpretation of fluid inclusion data from previous studies, and assuming a gradient of 55°C/km for NqE, crystallization temperatures for fluids from OF1, OF2, and STF were estimated at approximately 200°C, 160°C, and 150°C, respectively.Integrating crystallization temperatures, crosscutting relationships and subsidence curves allowed for the identification of four distinct fracturing events within the reservoir. The first event, pre-Late Cretaceous in age, corresponds to compaction-related fracturing (NTF). The second event (Late Cretaceous), generated overpressure fractures OF1 (86 Ma) coinciding with increased thermal maturation of HC. The third event, during the Paleogene involved the formation of TF (S1; 58 Ma) to the west, associated with the structuring of the AFTB and the onset of HC migration. In the eastern sector, OF2 (48 Ma) developed during the maximum burial of the unit in the NqE, coinciding with HC expulsion. Finally, during the Late Oligocene and Miocene, STF (25 Ma), S2 (15 Ma), and S3 (12 Ma) were developed, associated with the structuring of the Andean foreland. Información suministrada por el agente en SIGEVAPalabras Clave
Natural FractureNeuquen BasinReservoir