Impact of tectonic shortening on fluid overpressure in petroleum system modelling : Insights from the Neuquén basin, Argentina

J. Berthelon (1) , A. Brüch (1) , D. Colombo (1) , J. Frey (1) , R. Traby (2) , A. Bouziat (1) , M.C. C Cacas-Stentz (1) , T. Cornu (3)

1 IFPEN - IFP Energies nouvelles
2 Total E&P
3 CSTJF - Centre scientifique et Technique Jean Feger

Petroleum System Modelling (PSM) is a method which reproduces the burial history of sedimentary basins, together with rock properties, thermal and stress state, fluid flow and chemical transfers. The Vaca-Muerta Formation (Fm) in the Neuquén foreland basin, Argentina, presents exceptionally high overpressure despite the latest erosional history coeval with the current basin shortening. PSM currently accounts for vertical compaction laws only, which are not sufficient to match the observed pore pressure while keeping permeability values realistic. It also prevents to discuss the relationships between natural fracturing and the basin hydrodynamic. To assess these phenomena, a code coupling a PSM and a geomechanical simulator is used, in which we consider a 3D poro-elastoplastic geomechanical framework that accounts for both burial and tectonic compaction. Using this coupled approach, we calibrate porosity and pore pressure in a 3D geological model of the Neuquén basin using successive tectonic shortening phases related to the Andean subduction. Compared to PSM results using similar parameters, this study quantifies how much Andean tectonic deformation influenced pore pressure evolution in the basin. It shows that Late Miocene to recent tectonic could explain most of the overpressure observed in the Vaca-Muerta Fm. A shear-induced fracturing index provided by the constitutive model suggests that fracturing in the Vaca-Muerta Fm is very likely to occur during one of the main Andean deformation phases. The work suggests that pore pressure prediction in regions that have been subjected to lateral tectonic loading should be handled considering a 3D geomechanical approach. Using the Neuquén basin as an example, the present study discusses the impact of tectonic in pore pressure evolution, and its role in natural fluid migration in sedimentary basins subjected to tectonic deformation.

Mots clés: Sedimentary basin; Fluid overpressureNeuquén basin; Seal rock fracturing; Geomechanics; Numerical modelling

Domaines: Sciences de la Terre; Géologie appliquée; Sciences de l'environnement

J. Berthelon, A. Brüch, D. Colombo, J. Frey, R. Traby, et al.. Impact of tectonic shortening on fluid overpressure in petroleum system modelling : Insights from the Neuquén basin, Argentina. Marine and Petroleum Geology, 2021, 127, pp.104933. ⟨10.1016/j.marpetgeo.2021.104933⟩. ⟨hal-03167487⟩