Pyrrolil-silicon compounds were investigated by different theoretical approaches.Model monomers consisted in pyrrole ring N-substituted with silylmethoxy and silylhydroxy end-groups through propyl chain spacer, designated as PySi and PySiOH. Geometrical, vibrational and electronic properties, as well as chemical reactivity, are discussed and compared with Pyrrole (Py) and N-propylpyrrole (N-PrPy) that were studied in parallel for reference purposes and methods validation. The electronic distribution between PySi and PySiOH importantly differs, being the former electron donor, as Py and N-PrPy. Conversely, PySiOH presents donor-acceptor character with LUMO energy level localized on the silanol end-group.Global and local reactivity descriptors predict PySiOH more reactive than PySi with two preferential reactive sites: electron-rich Py ring and electron-deficient silanol group. Based on experimental studies, oligomers of PySiOH linked α−α' via Py rings (α−α'Py n SiOH, n = 2,3) were considered as model molecules of hydrolyzed PySi. The most stable structures were derived from randomly generated α−α'Py n SiOH that were optimized at semiempirical AM1 and refined with M05-2X/6-31G(d,p). Conformational analysis of dimer and trimer structures points to stability enhanced by molecular packing. Nonetheless, NBO and RDG results indicate that oligomers stability is dictated by the cooperative contribution of hydrogen bonding between silanol end-groups and dispersive vdW interactions between silanol and the π system of Py ring.The latter interaction resulting from electron delocalization induced by electron deficient silanol group seems to determine the smaller gap energy of T-shaped OH-π arrangements. The theoretical findings support the peculiar chemical behavior revealed by experiment.

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The most complex components in heavy crude oils tend to form aggregates that constitute the dispersed phase in these fluids, showing the high viscosity values that characterize them. Water-in-oil (W/O) emulsions are affected by the presence and concentration of this phase in crude oil. In this paper, a theoretical study based on computational chemistry was carried out to determine the molecular interaction energies between paraffin-asphaltenes-water and four surfactant molecules to predict their effect in W/O emulsions and the theoretical influence on the pressure drop behavior for fluids that move through porous media. The mathematical model determined a typical behavior of the fluid when the parameters of the system are changed (pore size, particle size, dispersed phase fraction in the fluid, and stratified fluid) and the viscosity model determined that two of the surfactant molecules are suitable for applications in the destabilization of W/O emulsions. Therefore, an experimental study must be set to determine the feasibility of the methodology and mathematical model displayed in this work.

Production of heavy and extra-heavy crude oils generally entails high costs, especially in the winter season, due to heat losses. This work studies the effect of a flow enhancer (a chemical formulation based on biodiesel and oxidized biodiesel of soy oil) on the viscosity of heavy crude oil from different wells in Northern Mexico. The observed results indicate a non-linear decreasing behavior of viscosity concerning temperature and volume fraction of the viscosity reducer. It is also presented a theoretical model that predicts the flow increase that can be achieved using the enhancer in systems in which crude oil temperature is higher than the temperature of the environment. Results showed adequate correspondence between experimental and predicted data. It was found that the enhancer increases the volume of crude oil that can be processed without varying pressure gradient.

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