Seeded four in Melbourne, Sela, 17, produced an excellent performance to beat his Cypriot opponent 6-3 6-3 to set up a last four meeting with top seed Yibing Wu of China.
Reflecting on the performance, Oliel's coach Jan Pochter said: "Yshai was very aggressive today against a player who likes to wear down his opponents in long, exhausting rallies.
"Yshai got in a really high percentage of good first serves. He feels really good and his confidence is growing from game to game and his belief that he can go all the way is giving him a lot of motivation."