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Kinetic Study of Extra Heavy Crude Oil Upgrading Using Hydrogen Donors Under Cyclic Steam Injection Conditions

Cesar Ovalles, Jorge Martinis, Edgar Cotte, and Jose Luis Benitez. Centro de Catálisis, Petróleo y Petroquímica, Universidad Central de Venezuela, Caracas, Venezuela

Extra-Heavy Crude Oil Upgrading using a tetralin as hydrogen donor under steam injection conditions (methane and the mineral formation) led to an increase of at least three degrees in API gravity, three-fold viscosity reduction and, approximately, 8% decrease in the asphaltene content with respect to the original crude. Two different kinetic studies were carried out in order to determine the kinetic model for the upgrading process. Firstly, a reaction model involving four pseudo-components (light, medium, heavy and asphaltene fractions) was used and the Arrhenius pre-exponential factors and activation energies were determined. Using a continuous bench scale plant, the reaction between Hamaca pseudo-components under steam injection conditions was evaluated at different temperatures (280-315°C) and residence times (24-64 h). The results showed a good match between the calculated and experimental API gravities of the upgraded crude oil with an average relative error of 4%. Secondly, different experiments at various crude oil to tetralin weight ratios were carried out to determine the tetralin reaction order (n). The results indicate that n = 0.95 with a correlation factor of 0.9966 for several batch experiments at different residency times (12-48h). Finally, combining the four pseudo-component model and the tetralin reaction order (n_=_1), a general reaction scheme was obtained to describe the kinetic model for the upgrading process.