Abstract: The invention concerns an enhanced oil recovery process improving the gas sweeping of an oil formation reservoir comprising at least one injection, through at least one injection well, either simultaneously or separately, of a plug of solution, preferably aqueous, of at least one surfactant and of a gas and/or steam plug (or "slug"), so as to form a foam.At least a portion of said reservoir is swept by said foam and the hydrocarbons are recovered through at least one producing well. The surfactant complies with the general formula R.sub.F --Y--X wherein R.sub.F is a perfluoric carbon radical, Y is a single bond or a divalent carbon radical containing at least one oxygen, sulfur and/or nitrogen atom, and X is a hydrophilic group.

Abstract: A hydroformylation catalyst system consisting essentially of a complex combination (1) of rhodium, carbon monoxide and triarylphosphine or triarylphosphite ligand, a compound (2) of cobalt and a triarylphosphine or triarylphosphite compound (3), wherein said system contains a source of at least one conjugated diene (4).

Abstract: This invention relates to a catalyst system for the hydroformylation of propene consisting essentially of a catalytic complex of rhodium, carbon monoxide, and a triarylphosphine, and a cobalt compound; to the process for stabilizing and/or regenerating a catalyst complex combination of rhodium, carbon monoxide, and a triarylphosphine comprising adding a cobalt compound to said catalyst complex; and to the process of hydroformylating propene with said catalyst system.