Controlled reduction of aromaticity of alkylated polyaromatic compounds by selective oxidation using H2WO4, H3PO4 and H2O2: A route for upgrading heavy oil fractions

Heavy crude oil fractions which form the residues from fractional distillation are a significant proportion of current hydrocarbon reserves. However, processing residues for use as chemicals or fuels is hampered...

Hydrate Agglomeration in Crude Oil Systems in Which the Asphaltene Aggregation State Is Artificially Modified

Summary Some crude oils contain naturally occurring surfactants that avoid hydrate agglomeration. Natural hydrate antiagglomeration has been linked to different crude oil fractions, including asphaltenes. Asphaltenes can promote the formation of stable water-in-oil (W/O) emulsions due to their amphiphilic properties. The surfactant-like behavior of asphaltenes is related to their aggregation state. Asphaltenes are strong emulsifying agents when in an aggregated state but weak emulsifying agents when either precipitated or well solubilized in the bulk oil phase. The asphaltene aggregation state may be artificially modified, changing its interfacial activity, by mixing crude oil with heptane–toluene mixtures. This work investigated the influence of the asphaltene aggregation state on gas hydrate agglomeration. Results show that the natural hydrate antiagglomerant properties of crude oils can be highly dependent on the artificially induced asphaltene aggregation state. For instance, if asphaltenes were induced to be solubilized into the bulk oil phase, the natural hydrate antiagglomerant behavior was diminished. However, when asphaltene aggregation was induced, gas hydrate agglomeration was avoided. These new findings could have significant implications for the implementation of novel hydrate management strategies that can reduce or eliminate the need for external interventions and hence minimize capital and operational expenditures by taking advantage of the intrinsic natural antiagglomerant properties of some crude oils.

DEVELOPMENT OF A NEW CORRELATION TO PREDICT VISCOSITY OF PETROLEUM FRACTIONS

Knowledge of temperature dependence of liquid viscosity plays an important role in a variety of engineering problems in oil and gas transportation. In this work an experimental database was established, which consists of kinematic viscosity for several petroleum fractions in kerosene and gas oil ranges. A new correlation was developed to predict the effect of temperature on Kinematic Viscosity of petroleum fractions of a wide boiling range from 30 to 200 C. This correlation is based on the correlation of viscosity of pure hydrocarbons that had been developed by Mehrotra (1995). Fitting parameters have been evaluated for 235 experimental data points from 31 true boiling point fractions of Libyan crude oils and for 144 data points Arab heavy, Arab medium, and Arab Berri crude oils. In addition, fitting parameters have also been evaluated for both Libyan and Arabian and other world crude-oil fractions. The proposed correlation fits the kinematic viscosity data with an overall average relative error of 2.7 % for the 33 Libyan crude oil fractions and 2.4 % for the 167 Arabian crude oils fractions, and 3.0 % for the 35 other world fractions.