PRESENCIA DE HIDROCARBURO VINCULADO A LOS DEPÓSITOS BARITO-POLIMETÁLICOS DEL ÁREA DE COLIPILLI, SECTOR CENTRO-OCCIDENTAL DE LA CUENCA NEUQUINA, ARGENTINA

SALVIOLI, MELISA; LAJOINIE, MARÍA FLORENCIA; CESARETTI, NORA; LANFRANCHINI, MABEL ELENA; DE LA CAL, HERNÁN; RUIZ, REMIGIO

Mendoza

Congreso; X Congreso de Exploración y Desarrollo de Hidrocarburos; 2018

Instituto Argentino del Petróleo y del Gas

In the Colipilli area (central-western sector of the Neuquén basin, Neuquén province), the presence of hydrocarbons traces in barite deposits hosted in the contact zone between Chorreado Member, Huitrín Formation (Early Cretaceous), and intermediate composition subvolcanic bodies of Naunauco Group (60-70 Ma, Late Cretaceous-Terciary) was studied. These traces were recognized as fluid inclusions (FI) trapped together with aqueous fluids in barite crystals.The characterization of the FI was carried out through detailed petrographic studies and analytical techniques such as: (1) UV incident fluorescence that allowed inclusions with fluorescent hydrocarbons to be detected, (2) Raman spectroscopy, which determined the gaseous composition inside the inclusion (as methane, CO2) and (3) micro-thermometric studies that defined the physicochemical conditions of the FI formation (temperature, salinity).The UV incident light allowed two types of FI to be identificated, a non-fluorescent set, of aqueous nature, and a bluish tones strong-fluorescence one, of organic nature that indicates high values of density coefficient in the range of 40 ° API.No organic gaseous phases were identified through Raman spectroscopy studies in any of the two identified set, however, the strong fluorescence in the Raman spectra of the organic FI indicated the presence of liquid hydrocarbon.Finally, during the heating Micro-thermometric-assays, aqueous FI became homogeneous between 162 y 241°C, while the liquid hydrocarbon contained in organic FI was cracked generating gaseous phases. Thus, the homogenization temperature of these inclusions does not correspond to the original entrapment temperature of the fluid, but indicates the type of hydrocarbon that they contain. This organic fluid cracking-temperature was 81°C, value located between the point of hexane and heptane.According to the performed studies, the identification of liquid hydrocarbons in FI hosted in barite crystals reveals the occurrence of a hydrocarbons migration process favored by the aqueous fluids circulation. In this sense, the thermal input of Late Cretaceous-Tertiary magmatism could be the organic matter cracking generator. This organic matter could have been contained in the carbonate host-rock of the Chorreado Member or in the source rocks present in the area.In the case that the hydrocarbon generation model will be verified, the FI study could become a characterization and prospecting complementary method of petroleum systems in which igneous rocks were participate.