Abstract: A method of producing highly viscous oil from an underground formation penetrated by a well. Steam is injected through a first channel into the lower part of the formation. At the same time, previously recovered oil from the formation is injected through the well in a channel surrounding the steam channel to the upper part of the formation. This native oil insulates the formation from the steam and also serves to block the steam from rising in the formation. The heated oil can then be recovered from an adjacent well or injection can be stopped and the oil can be recovered from the well through which the fluid was injected.

Abstract: In the recovery of sulfur from hydrogen sulfide-containing gases wherein the first of a series of reactors is operated under conventional Claus conditions, one or more of the remaining catalytic reactors in the sulfur plant are operated at temperatures of the order of from about 250.degree. to about 400.degree.F. whereby free sulfur is deposited on the catalyst, regeneration of such catalyst is effected by heating a portion of the first reactor-condenser effluent to 500.degree.-700.degree.F. and flowing the resultant hot gas through the deactivated catalyst bed to vaporize free sulfur therefrom and regenerate the catalyst. Before placing the freshly regenerated catalyst bed back on stream, it is cooled with unheated first reactor-condenser effluent to a temperature of from about 250.degree. to about 400.degree. F. Thereafter the above cycle is repeated.