Cuyo basin

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This page is currently being authored by a student at the university of Oklahoma. This page will be complete by December 13, 2020.

Intro and History

The Cuyo basin is a sedimentary onshore basin that lies in the Mendoza Province of western Argentina on the South American plate. The basin occupies roughly 30,000 Square kilometers (12,000 Square miles) and contains 2 major sub-basins which are the Cacheuta in the north and the Alvear in the south. The  basin encompasses a group of Triassic extensional subbasins that are a product of a transitional environment dating back to the separation of  South America and  Africa. Later, in the Miocene, Andean compression began to invert the Triassic extensional structure, and the newly formed foreland organic clastic wedge buried the shales of what is now the Cacheuta subbasin into the oil generating window.[1] The Sedimentary sequences have unveiled complex interactions between alluvial, fluvial, deltaic, & lacustrine depositional systems. The first oil found in Argentina came in December of 1907, when the town of Comodor Rivadavia was digging wells in search of water.[2] 27 years later the first well was drilled on the Cuyo basin in the field of Tupungato and was quickly followed by another set of wells in the Barrancas field.[3] Today operators from all around the world such as Vintage Petroleum Inc. and Royal Dutch Shell operate on the various field that make up the Cuyo basin.[4]

Future potential & Geological risks and uncertainties

A map showing the maturation level of each subbasin with respect to the oil generating window.[5]

The U.S. Geological Survey (USGS) estimated a mean undiscovered, but recoverable resources of 236 million barrels of oil and 112 billion cubic feet of gas in the Cuyo basin. Given the uncertainty of the level of thermal maturation the Alvear lacustrine shale was not quantitively assessed thus all of the estimated reserves are located in the Cacheuta subbasin.[1] If the Alvear subbasin were found to be within the oil generating window it is assumed that the levels of undiscovered hydrocarbons would more than double as operations in the Cacheuta have been taking place for more than 80 years. Beginning in 2014, unconventional reservoir analysis began and has led Geologists to believe that there are larger reserves of oil than previously expected, however the majority of production comes from conventional reservoirs.

Petroleum elements

The source rock of the Cuyo basin is the middle Triassic Cacheuta formation and it is believed that some portions of the recoverable oil have been retained within the Cacheuta formation lacustrine shales following oil migration into conventional traps.[6] There are 2 prominent types of trap and seal combinations present in the Cuyo basin. The first and most prevalent is a conventional trap, majority folds due to the development of the Andean mountain range, with a conventional mud rock style seal. The second, is a Stratigraphic trap due to the facies change because of the presence of a  fluvial system which contains a mixture of tightly packed sediments which in turn serve as the seal. The key to understanding a reservoir is determining the rocks permeability which is connected to its porosity. In the case of the Cuyo basin the deltaic, fluvial sandstone reservoirs serve as an excellent reservoir as they have good porosity which allows them to hold and store the hydrocarbons as well as great permeability which allows for the hydrocarbons to flow.

Petroleum and facility Engineering

Lujan de Cuyo refinery operated by YPF.[7]

The Cuyo basin is home to a wide variety of international companies within the petroleum industry ranging from majors like Shell to small companies primarily based in the U.S. such as Vintage oil and gas.[4] South Americas is thought to have very large unconventional reserves, so many foreign companies are attracted to basins like the Cuyo by its potential economic prosperity. YPF owns the largest refinery in the area. The Lujan de Cuyo refinery operated by YPF is 1 of 2 main refineries in the basin.[8] Wells drilled in the basin are unique due to their shallow depth which usually fall in the range of 6,000 to 7,200 feet.


  1. 1.0 1.1 Schenk, C.J., Brownfield, M.E., Tennyson, M.E., Le, P.A., Mercier, T.J., Finn, T.M., Hawkins, S.J., Gaswirth, S.B., Marra, K.R., Klett, T.R., Leathers-Miller, H.M., and Woodall, C.A. (2017, July 18). Assessment of Undiscovered Oil and Gas Resources in the Cuyo Basin Province, Argentina, 2017. USGS Science for a Changing World.
  2. Centennial of the Discovery of Oil in Argentina. (2006). Banco Central de La República Argentina.
  3. Drummond, K. J., Sumii, T., Wakita, K., Matsubayashi, O., Fujii, K., Moritahi, T., Palfreyman, W. D., Yrigoyen, M. R., & Corvalan D., J. (2000). Explanatory Notes for the Energy-Resources Map of the Circum-Pacific Region, Pacific Basin Sheet. USGS Science for a Changing World.
  4. 4.0 4.1 OGJ Online Staff. (2001, August 9). Vintage acquires Argentina blocks from Shell unit. Oil & Gas Journal.
  5. Legarreta, L., & Villar, H. J. (2011). Cuyo Basin Cacheuta Fm (Triassic)[Map].
  6. Dellape, D. (1995). AAPG Datapages/Archives: Structural Inversion and Oil Occurrence in the Cuyo Basin of Argentina. AAPG Datapages.
  7. Repsol. (2009, August 19). The Lujan de Cuyo re nery (Argentina), with the Andes in the background. [Photograph]. Repsol.
  8. Business areas. (2009, August 19). Repsol.