 Doheny's Cerro Azul No.4 well, located by Ezequiel Ordonez, became the largest daily production record holder in 1916 at 260,000 bbl.Geophysical studies, in particular gravimetry, starting in 1920 led to the discovery of the Poza Rica Field in 1932 and Moralillo Field in 1948, on the west flank of the Golden Lane in the Tamabra forereef facies.