Evaluación de los procesos diagenéticos y modelado bidimensional del sistema petrolero Los Molles-Lajas/Punta Rosada en el Yacimiento Río Neuquén, Cuenca Neuquina, Argentina

BERDINI, O.; RODRÍGUEZ, J.F.; MATHEOS, S.D.; SPALLETTI, L.A. Y VILLAR, H.J.

Mar del Plata

Congreso; VIII Congreso Exploración y Desarrollo de Hidrocarburos, Actas; 2011

Instituto Argentino del Petróleo y Gas

The aim of this work is to identify and integrate the processes that led to the entrapment of gas in reservoirs of the Lajas and Punta Rosada formations (Jurassic) in the Río Neuquén area. The study combined subsidence analysis, the diagenetic processes occurred during the burial of the Lajas and Punta Rosada formations and the generating characteristics of the source shales of the Los Molles Formation. This information was integrated into a two-dimensional model that allowed evaluating, with some degree of approximation, the main features of the reservoirs for each of the hydrocarbon migration events and how they evolved until depict their current characteristics. The comparison between age and thickness of the stratigraphic record and thermal gradient, allowed to define that mesogenetic processes occurred during deep burial (microstilolitization, microfracturing, oil accommodation and subsequent cracking, and late quartz growth), and would have started in the Albian. Microfracturing processes are common in depth. Two stages of microfracturing are defined: the first one is characterised by micropores showing dry oil occlusion, and the second one consists of microfractures which are free of pyrobitumen. This second microfracturing process generated still open secondary porosity. The average porosity values range from 8% (4000 meters) to 10% (3000 meters), while the permeabilities are always less than 0.1 mD. Based on these concepts the Los Molles-Lajas/Punta Rosada petroleum system in the Río Neuquén area, generated a system of basin center gas mixed and therefore it is independent of the structure.