Parejas, Ronal de la Cruz; Moura, Francisco José (Advisor). Effects of nanoparticles, Al 2 O 3 -NiO, TiO 2 e (Mg,Ni)O, on viscosity of heavy oil during aquathermolysis. Rio de Janeiro, 2014. 133p. MSc. Dissertation -The global demand in energy will increase by 50% over the next 20 years and oil will remain the main source of energy. Among the different types of crude oils, attention has been focused on the recovery of heavy and extra heavy oils, because the conventional resources as light and medium oils are globally decreasing. Heavy and extra heavy oils constitute 70% of world reserves, but lead to problems due to their high viscosity and complex composition.Therefore, the recovery of these oils represents a challenge for the oil industry.Conventional methods recover about 30% of oil in the reservoir and enhanced oil recovery (EOR) allows to get higher values. The most used method is the injection of steam whose main mechanism of this process is the heating of oil.Consequently there is a reduction of viscosity followed by an incipient cracking, phenomenon affected by the presence of steam water, which needs further studies. This work presents a study of the influence of nanoparticles in the steam injection (aquathermolysis), which can generate a catalytic effect; it enhances the incipient cracking and decreases the viscosity. A heavy oil with viscosity of 4730 cP at 25 °C was used in bench scale to evaluate the effects of time, temperature, type and concentration of nanoparticles (Al 2 O 3 -NiO, TiO 2 and (Mg,Ni)O) on viscosity and composition of the crude oil. The results showed that the presence of TiO 2 nanoparticles with steam water may improve the oil quality, by reducing the heavy fractions, and reducing its viscosity up to 13.4%.The technique was improved with increasing either temperature or time of aquathermolysis.