(55b) Analysis of Catalytic Aquathermolysis on the Physicochemical Properties and Maltenes-Asphaltenes in Colombian Heavy Crude Oils By Using 1H-NMR

Catalytic aquathermolysis is an enhanced oil recovery (EOR) technique that uses steam injection with a catalyst to produce crude oils in reservoirs with lower energy requirements and less time than conventional methods. Therefore, the crude oils obtained are of better quality due to the new physicochemical properties and composition of maltenes (saturates, aromatics, resins) and asphaltenes. In this work, the catalytic aquathermolysis process was studied in two Colombian heavy crudes. The reactivity tests were carried out in a batch microreactor at 270°C and saturation pressure of 800 psi, for 66 hours, using iron naphthenate at 100 ppm with respect to the metal ion. The use of the catalytic aquathermolysis technique reduced the gas yield in the range of 1 to 3 % w/w, the viscosity from 35 to 60 %. Additionally, distillation curves (ASTM D7169) of the improved crudes showed conversions of the 525°C+ heavy fractions between 4 and 8 %, showing a significant decrease in complex fractions with high boiling points.

Analysis of the average molecular parameters (AMPs) via 1H-NMR spectroscopy confirms that the reactivity and products yield vary according to the complexity of the molecular structure of the maltenes and asphaltenes present in the heavy crude oils. The average molecular parameters showed that the major differences concerning the base crude were aromaticity and alkyl chain length. During the application of this recovery method, it was established that the selectivity and reactivity depends on the composition of the heavy crude oil. Finally, the improvement of the physicochemical properties of crude oil at reservoir conditions is a complementary recovery mechanism to the conventional steam injection process, and in turn, allows the transformation of complex fractions towards the formation of species of smaller size and molecular weight.