The Vaca Muerta (Dead Cow) shale formation in Argentina is around 30,000 square kilometres. It was discovered in 2011.
In 2012, Bloomberg Business appears to be the first source to compare it with Belgium. Since then, many other journalists appear to have copied Bloomberg’s comparison.
Petronas to Develop Shale Oil in Vaca Muerta
February 18, 2014 — 4:57 PM GMT
YPF is seeking shale partners to develop Vaca Muerta, an areas the size of Belgium that contains at least 23 billion barrels of oil.