The US independent had owned a working interest of 43.2% on the Bajo del Toro and Cerro Avispa areas, Argentina's state oil company said in regulatory filing.
YPF, Argentina's state-led oil company, had already operated the blocks with a 46.8% stake.
YPF operations reports have listed both areas as among those targeted for unconventional exploration in Neuquen, the heart of Argentina's famous Vaca Muerta shale.
