Ratio Oil Exploration (1992) Limited Partnership explores for and produces oil and gas in Israel. In 1992, Yeshayahu (Shaikeh) and his son Yigal Landau, in collaboration with the Rotlevy family, the late Zvi Tzafriri, and Geologist Eitan Eisenberg, established the “Ratio Oil Exploration (1992)” – Limited Partnership for the purpose of oil exploration in Israel.