See discussions, stats, and author profiles for this publication at: UN NUEVO SISTEMA PETROLERO EN EL FLANCO NORTE DE LA CUENCA DELGOLFO SAN JORGE: REVALORACIÓN DE ÁREAS MARGINALES YEXPLORATORIASConference Paper· January 2002CITATIONS4READS1693 authors, including:Some of the authors of this publication are also working on these related projects:Fossil mammals of Chilean PatagoniaView projectSedimentology of volcaniclastic fluvial-alluvial environmentsView projectEduardo BellosiMuseo Argentino de Ciencias Naturales (CONICET)122PUBLICATIONS1,556CITATIONSSEE PROFILEAll content following this page was uploaded by Eduardo Bellosi on 07 June 2016.The user has requested enhancement of the downloaded file.
UN NUEVO SISTEMA PETROLERO EN EL FLANCO NORTE DE LA CUENCA DEL GOLFO SAN JORGE: REVALORACIÓN DE ÁREAS MARGINALES Y EXPLORATORIASEduardo S. Bellosi1, Héctor J. Villar2y Guillermo A. Laffitte31.Museo Argentino de Ciencias Naturales, CONICET. Buenos Aires. [email protected]2.FCEN-Dep. Cs. Geológicas, Universidad de Buenos Aires-CONICET. [email protected]3.Consultor. Buenos Aires. will[email protected]Keywords: San Jorge Basin. Colhue-Huapi. Petroleum systems. Neocomian. Abstract.A NEW PETROLEUM SYSTEM IN THE NORTH FLANK OF THE SAN JORGE BASIN: REAPPRAISAL OF MARGINAL AND EXPLORATION AREASThe Pozo D-129 Formation has been historically considered the unique source unit in the eastern, most prolific, region of the San Jorge Basin. The hydrocarbon generative beds bearing lipid-rich, oil-prone, unstructured kerogen were formed in a large lacustrine system (Lower Cretaceous). Towards the basin margins, its generation potential decreases considerably due to low-quality organic facies associated to limited thickness and depth. The evaluation of geologic and geophysical information of exploration wells of the Colhue-Huapi Area (North Flank) indicated the potential existence of a second hydrocarbon source, where D-129 has no effective generation capability. This hypothesis found support on geochemical analyses of rocks and oils that pointed to hydrocarbon generation from a Neocomiano(Las Heras Group) source, charging the reservoirs of the Chubut Group. The Neocomian lacustrine deposits of the Pozo Anticlinal Aguada Bandera-1 Fm. are concentrated in restricted depocenters (grabens and hemigrabens) formed during the late rift stage of the basin. The source facies, identified in the LV-2 (Las Vacas) and RChN x-1 (Río Chico Norte) wells, have good organic contents, moderate pyrolysis yields and mixed amorphous/structured organic matter. Their characteristics are comparable to those typically recognized in the Western Flank of the basin, where this unit is a proved oil source. The comparison of an oil recovered from the Mina del Carmen reservoir at the Ea.LE.x-101 (Estancia La Escondida) well with oils of a neighbor field showed significant geochemical differences, indicating distinct origins. In particular, a Neocomiano source has been attributed to the Ea.LE.x-101 oil. The inferred generation of Neocomiano hydrocarbons in marginal sectors