A New Lumping Scheme of Analytical Data for Compositional Studies

This paper presents a new algorithm to lump fluid compounds into hypothetical components. It has been designed to bridge the gap between the increasing amount of analytical data provided by modern lab equipments and the simplified fluid description required in compositional model studies. The main feature of the method is a lumping scheme based on the similarities of a few properties of all the compounds identified by chromatographic analysis. An iterative clustering algorithm around mobile centers yields a classification into pseudo-components optimum with respect to the considered equation of state. It can be adapted to any equation of state, any number of compounds or properties. An other noticeable feature of this procedure is the definition of a mixed calculation of critical properties. A criterion to choose between an accurate calculation of true critical properties and the classical mixing rules is suggested. Numerical simulations of PVT behavior were completed for an oil and a gas condensate defined by 150 compounds. The clustering algorithm determined simplified fluids lumped into 7 and 5 components. True critical properties calculation for the hypothetical components and classical mixing rules were tested and the mixed calculation proved to be the best.