Abstract: The invention relates to a method for monitoring a process for refining a feedstock of hydrocarbons, in which: a) a signal representative of the transverse relaxation time of the different entities of an effluent resulting from said refining process, in particular an effluent comprising solid entities, is acquired by proton NMR, b) the signal measured is modeled using a mathematical function comprising several components, each component corresponding to a dynamic range of the entities of said effluent, c) the following are extracted from each of the components of the mathematical function: the transverse relaxation time of each of the components, the intensity of each of the components, d) a value of parameter characteristic of said effluent is determined from at least one intensity determined in stage c), e) a signal for controlling the refining process is generated as a function of said characteristic parameter.

Abstract: The invention relates to a method for determining a parameter representative of the stability of an asphaltene-containing petroleum product, said petroleum product being an effluent derived from a hydrocarbon feedstock conversion process or being a mixture of hydrocarbons, using proton NMR to determine a threshold value of said parameter representative of the stability, this threshold value constituting a boundary between a stability domain and an instability domain of a petroleum product. According to the invention, the parameter representative of the stability is a T2mean/T1mean or T1mean/T2mean ratio. The invention also relates to a method for monitoring a conversion process, in particular a deep conversion process, or a mixture of hydrocarbons, using this method of determination.