Patent ID: 6985841

Claim:
A modelling method allowing to predict, as a function of time, the detailed composition of fluids produced by an underground reservoir under production, in at least one thermodynamic zone defined in the model, characterized in that it comprises: discretizing the reservoir by means of a grid, each grid cell containing one or more phases, including at least one non-aqueous phase; determining the variation of thermodynamic parameters of the non-aqueous phases necessary for <<Black Oil>> (B.O.) type modelling during stages of a thermodynamic path followed by the fluids in the reservoir; defining the fluids by a detailed representation with N rd components and/or pseudo-components; determining at least one state function with n parameters allowing to simulate, at least in the input data preparation stage, the thermodynamic behaviour of the fluids during the stages of the thermodynamic path followed, so as to generate, in each said thermodynamic zone where it is desired to perform a delumping operation, additional input data; converting the thermodynamic behaviour of each non-aqueous phase into input data suited for a B.O. type thermodynamic representation, this input data being completed by said additional input data suited for a delumping operation; carrying out B.O. type modelling allowing to determine, in each cell and at successive time intervals, thermodynamic characteristics of each non-aqueous phase and data representative of phase displacements in the reservoir; and carrying out a delumping operation in order to obtain the detailed composition of the fluids in each cell.