Prediction of some physicochemical properties in Colombian crude oils upgraded by catalytic aquathermolysis using UV-VIS spectroscopy associated with chemometric methods

The simulated distillation curve (ASTM/D-7169) is a quantitative method to determine fractions of crude oils by boiling point temperature ranges (36-720 °C). In this work, 45 samples of typical Colombian crudes were selected, and the samples were produced under conventional process. Also 8 upgraded crude oils under catalytic aquathermolysis conditions at laboratory scale were added. The tests were developed at 270 °C and 800psi (@25 °C) during 66 h of reaction. In addition, 30 samples were selected for density tests, according to the pycnometer method. Subsequently, the crude oil samples under study were diluted in chloroform and analyzed by UV-VIS Spectroscopy. The UV-VIS spectra were correlated with selected properties by using PCA-MLR and PLS models. The distillation curves of the crude oils were modelled using the Riazi probability function. The prediction models of parameters To, A, and B from the Riazi probability function exhibited R² correlation coefficients, higher than 0.94. The correlation model for the crude oil density showed a much better coefficient, higher than 0.99 and Root-Mean-Squared-Error (RMSE) close to 0.004. Additionally, even more important is the contribution of the use of UV-VIS spectroscopy as a useful tool to quickly evaluate the quality of crude oil.