MMH architectural study of asphaltenes aggregates formation in crude oils and its influence on viscosity
The high molecular weight components present in heavy crudes, tend to form molecular aggregates which are present as a dispersed phase and which manifest in the high viscosity values of these fluids. There is evidence that the action of a flow enhancer or viscosity reducer is based on the interaction of its active component with the molecular aggregates, in such a way that the volume fraction of the dispersed phase decreases with the consequent reduction of the viscosity. In this paper a theoretical study, based on computational chemistry techniques and stochastic modeling methods as the multiple minimum hypersurfaces (MMH) approximation, was carried out to determine the molecular interaction energies between asphaltenes molecules (dispersed phase in crude), and the molecules that constitute the active component of a flow enhancer whose main component contains an ester functional group. The expected qualitative behavior of the dispersed phase concentration and viscosity as a function of the enhancer concentration is also presented. Theoretical results indicate that the efficiency of the enhancer depends on both the molecular structure of the product that constitutes its active component and the composition of the crude oil, predicting a decrease of the asphaltene-asphaltene and asphaltene-paraffin aggregates with respect to the concentration of the ester functional group. These results were contrasted with the experimental behavior of viscosity with respect to the concentration of the enhancer, obtaining an adequate correspondence between both studies.
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