The chemical and physical structure of petroleum: effects on recovery operations

In a mixture as complex as petroleum, recovery chemistry can only be genera lized because of the intricate and complex nature of the molecular species that make up the crude oil. It is this complexity that leads not only to di fficulties in analyzing the recovered material but also in analyzing the or iginal oil in place. Moreover, the incompatibility of crude oil constituent s with each other is a continuing issue and the occurrence of suspended org anic solids during recovery (especially thermal) reduces the efficiency of a variety of processes. More detailed knowledge of the composition and reac tivity of petroleum will help in understanding the means by which models ca n be applied to understanding recovery processes. The models that are propo sed as a means of being applicable to the prediction of sediment (i.e., asp haltene, resin, wax) formation and deposition from petroleum due to changes in pressure, temperature and composition fall somewhat short in their stru cture. Further modeling needs involve an understanding of the chemistry of these materials and reflect the more modern approach to the physico-chemica l structure of petroleum in order to more correctly predict the onset of pr ecipitation as well as the location and amount of the sediment deposition i n the producing wells and in oil-transport pipelines. (C) 1999 Elsevier Sci ence B.V. All rights reserved.