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

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

Ciudad de Mendoza

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

Instituto Argentino del Petróleo y del Gas (IAPG)

Hydrocarbon records linked to barite-polymetallic deposits from the Colipilli area, central-western sector, Neuquén Basin, Argentina.In the Colipilli area (central-western sector of the Neuquén basin, Neuquén province), the presence of hydrocarbon 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-Tertiary) 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) incident UV light that allowed inclusions with fluorescent hydrocarbons to be detected, (2) Raman spectroscopy, which determined the gaseous composition inside the inclusion (as methane and CO2) and (3) micro-thermometric studies that defined the physic-chemical conditions for the FI and the barite crystals formation (temperature and salinity).The incident UV light allowed two types of FI to be identified, a non-fluorescent set, of aqueous nature, and a bluish tones strong-fluorescence one, of organic nature that indicates high values of Gravity coefficient in the range of 40° API.Non-organic gaseous phases were identified through Raman spectroscopy studies in any of the two identified sets; however, the strong fluorescence in the Raman spectra of the organic FI indicated the presence of liquid hydrocarbon.Finally, during heating test, micro-thermometric-assays, aqueous FI became homogeneous in the range of 162 to 241°C, while the liquid hydrocarbon contained in organic FI was cracked generating gaseous phases. Thus, this FI homogenization temperature does not correspond to the original entrapment fluid temperature, but also indicates the type of trapped hydrocarbon. This organic fluid cracking-temperature was 81°C, value located between the hexane and heptane vaporization point.According to the performed studies, the identification of liquid hydrocarbons in FI hosted in barite crystals reveals the occurrence of hydrocarbon 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 or unless it could be participated in this process. This organic matter could have been contained in the carbonate host-rock of the Chorreado Member or enclosed into the source rocks present in the area.In case of hydrocarbon generation model will be verified, the FI study could become a characterization and prospecting complementary method for petroleum systems related to igneous rock intrusions.