Olivera made himself a recognised name in his country, working many years in important Argentine comics, like the classic Nippur de Lagash, which he co-created with Robin Wood,[1] and Gilgamesh the immortal, which he also created and is widely considered his "magnum opus".
At age 20 he moved to Buenos Aires City, where he published his first drawings in the magazines Vea y Lea and Leoplán while he studied at the Escuela Panamericana de Arte with Hugo Pratt and Alberto Breccia.
He soon attracted the attention of comics writer and publisher Héctor Germán Oesterheld, for whose magazines Frontera and Hora Cero Olivera would illustrate several covers during the late 1950s and early 60s.
Olivera's script, which carries a greater fantasy and moral ambiguity than that of Nippur de Lagash, allowed the artist to develop an uncharacteristically tenebrist style, which turned it into a cult comic.
For a newspaper of Río Negro he also drew and wrote the comic Pepe Moreno in the late 90s, which tells of the adventures of a paleontologist concerned about the depredations of the national archaeological heritage.