Abstract: The invention relates to the use of a compound of the general formula (I), wherein A represents an alkanediyl radical having 2 to 4 carbon atoms, which may be substituted by one or more methyl and/or ethyl groups, and either R represents a linear or branched C1 to C4 alkyl group and R? represents a hydrogen atom, or R and R? are linked together to form a cycle, and the —R—R?— radical represents —CO—, as a tracer for use in a Single-Well Chemical Tracer Test, to determine the Residual Oil Saturation in oil reservoirs.

Abstract: The invention relates to the use of a compound of the general formula (I), wherein A represents an alkanediyl radical having 2 to 4 carbon atoms, which may be substituted by one or more methyl and/or ethyl groups, and either R represents a linear or branched C1 to C4 alkyl group and R? represents a hydrogen atom, or R and R? are linked together to form a cycle, and the —R—R?— radical represents —CO—, as a tracer for use in a Single-Well Chemical Tracer Test, to determine the Residual Oil Saturation in oil reservoirs.

Abstract: The fluid tracers according to the invention have the advantage of producing a memory effect fluorescent signal, that is to say a signal modified as a function of the physico-chemical conditions encountered in the medium through which the nanoparticles pass after injection into the geological underground area. The analysis of fluorescent signals in the fluids collected after diffusion makes it possible to deduce therefrom information on the characteristics of the oil reservoir.

Abstract: This invention relates to the development of nanoparticles, which can be used as tracers, in order to track the movement of fluids injected into an oil reservoir. The injected fluids diffuse through a solid geological medium which constitutes the oil reservoir, thus making it possible to study this latter by following the path of the injected fluids. The objective is in particular to monitor the flows between the injection well(s) and the production well(s) and/or to evaluate the volumes of oil in reserve and water in the reservoir and ultimately to optimize oil exploration and exploitation.

Abstract: A surfactant composition includes an alkaryl sulphonate compound (a) and an alkaryl sulphonate compound (b). The difference between the optimum salinity of compound (a) and the optimum salinity of compound (b) is greater than or equal to 3 g/L. The surfactant composition can easily be adapted to various operating conditions, and in particular to various conditions of salinity, in order to provide optimum enhanced oil recovery.