Abstract: A method of extracting highly viscous nonfracturable oil from earthen deposits is presented by the instant invention. A plurality of radially extending horizontal conduits direct heated hydrocarbon vapors into the formation. The vapors are selected to have a boiling point above the pour point of the viscous oil. Thus, as the vapors rise in the formation, they will be in heat exchange relationship with the viscous oil to cause the latter to flow downwardly. In addition to the thermal exchange of energy, the vapors will move toward molecular equilibrium with the viscous oil formation. This latter action will cause the vapors to "strip off" the more volatile, lower boiling components, from the descending liquid oil. The liquified oil, on the other hand, will condense the less volatile, higher boiling point fraction of the vapors.