The Vaca Muerta field is a supergiant shale oil field and shale gas located in Argentina. The field was discovered by Repsol-YPF, who announced the discovery in May 2011. The total proven reserves are around 927 million barrels (126×106tonnes), and production is centered around 5,000 barrels per day (790 m3/d). making it the third largest of its type in the world. In February 2012, Repsol YPF SA raised its estimate of oil reserves to 22.5 billion barrels
The field is a continuous tight oil and shale gas reservoir in the Vaca Muerta Shale of Jurassic and Cretaceous age. The Vaca Muerta Shale has long been known as a major petroleum source bed in the Nuequen Basin, with a total organic carbon content varying from 1 percent to 5 percent. The shale is at a depth of about 9500 feet where it has been found productive of oil and gas. Although called a shale, the Vaca Muerta is predominately marl.
Repsol-YPF recognized the productive potential of the Vaca Muerta Shale of the Neuquen Basin, and completed Argentina’s first shale gas well in July 2010, at the Loma La Lata field. Then in November 2010, the company completed a tight oil well in the Vaca Muerta Shale in the La Compana area. The first horizontal well in the Vaca Muerta was drilled and completed in August 2011. By October 2012, 31 wells had been drilled and completed, and another 20 had been drilled and were waiting completion. The drilling had extended the Vaca Muerta field to an area of at least 300 square kilometers.
One problem in attracting development was Argentina’s price controls on natural gas, keeping the price down to US$2.00-$2.50 per million BTU. However, the government exempted tight gas from controls, and in 2011 the Vaca Muerta gas was selling for US$4-$7. The higher gas prices attracted major oil companies, including ExxonMobil, Total S.A., and Chevron Corporation to the Vaca Muerta field.
Expropiation and nationalization
In April 2012, the Argentinean government sent to the Honorable Congress a law to expropriate 51% of the ownership of Repsol YPF SA, taking almost all the Repsol shares, sold by only 15.000 billion Euros in 1999, and without sending the privatization to the Honorable Congress.
The company had always been a national company but and is still a corporation, but the majority shareholder is the Argentine state. The government gave six months to reverse the production decline that forced the country to import petroleum from the Middle East, making oil prices rise. Argentina had been self-sufficient in oil until 1999.
On May 2013, YPF signed an agreement with US oil major Chevron Corp to define the terms and conditions of Chevron’s investment of up to $1.5 billion in vast Vaca Muerta shale field. YPF aims to drill 132 oil wells at the Vaca Muerta shale formation in Patagonia on 2013.
Source Wikipedia: http://en.wikipedia.org/wiki/Vaca_Muerta_oil_field