Oil & Gas Shale Potential of the Middle to Upper Ordovician in the Precordillera Basin, Argentina: Analogies from the Utica Formation (Appalachian Basin from U.S.A. and Canada), to the Gualcamayo, Las Vacas and Las Plantas Formations (Precordillera Basin, Argentina)

Miguel Ángel Pérez
Geologist, Owner, Artemap

The “Jáchal“ and “Niquivil“ exploratory blocks in the Precordillera Basin (Argentina), were studied and sampled in an exploratory project carried out by the OIL M&S oil company from the year 2006 to the mid of 2011. From detailed geological studies, geochemical sampling and geophysical surveys was determined that the pelitic and calcareous rocks from the Middle to Upper Ordovician have good oil potential. Simultaneously, seeps of dry oil were found in outcrops. Geochemical correlations from laboratory have permitted genetically associate these seeps of oil with Ordovician source rocks, and the same rocky interval (more than 300 meters -1000 feet- in thickness), have provided good shows of wet and dry gas in an exploratory well.

Precordillera Basin is considered an allochthonous terrane attached to the Gondwana continental margin throughout the Lower Paleozoic. It was probably originally part of the Laurentia paleocontinent, and became detached on the present North America Eastern margin.

Gualcamayo, Las Vacas and Las Plantas Formations in the Middle to Upper Ordovician interval from the Precordillera Basin, are a synchronous equivalent, and possibly in some way a paleogeographic linked piece, of the Trenton Group and the Utica Formation and equivalents from the Appalachian Basin of the U.S.A. and Canada. The Utica F. and equivalents intervals are source rocks in the productive Paleozoic Petroleum Systems of the Eastern North America. The Gualcamayo Formation, in the Precordillera Basin, has similar characteristics to them not only in their sedimentary facies and fossil content, but also by the amount, type and quality of organic matter it contain. These parameters are compared here, as well as the thermal maturity ranges in organic content for both formations, which in both basins varies between the oil window to the dry gas window, depending on the tectonic setting.

The Utica Formation has demonstrated to be very important in the states of the East part of the Appalachian Basin of U.S.A. and Canada, as Unconventional Oil and Gas plays and, taking into consideration the characteristics studied in the “Jáchal” and “Niquivil” exploratory blocks, it is probable that the equivalents in the Precordillera Basin will be. These notes are a partial synopsis of a detailed technical report on this topic, in which some comparative considerations between this interval of the Middle Ordovician and their equivalent of the Precordillera Basin are made.

AAPG Search and Discovery Article #90165©AAPG 2012 GEOSCIENCE TECHNOLOGY WORKSHOP, 2-4 December 2012, Buenos Aires, Argentina