The find has potential production of 200,000 cubic meters of gas and 370 barrels of oil per day, the company said in a release.
The well was drilled to a depth of 2,770 meters. Located in the province of Santa Cruz, where President Cristina Fernandez first rose to power, the discovery is a rare piece of good news for the president, who is struggling with an economy in recession and recent debt default.
Argentina needs more oil and gas production to halt a drain on central bank dollar reserves caused by expensive energy imports.
YPF is primarily focused on developing vast shale oil and gas formations in the Vaca Muerta area, also in Patagonia, but is struggling to attract the investment needed.