The low-temperature catalytic oxidation of
heavy crude oil (Xinjiang Oilfield, China) was studied
using three types of catalysts including oil-soluble, watersoluble,
and dispersed catalysts. According to primary
screening, oil-soluble catalysts, copper naphthenate and
manganese naphthenate, are more attractive, and were
selected to further investigate their catalytic performance in
in situ upgrading of heavy oil. The heavy oil compositions
and molecular structures were characterized by column
chromatography, elemental analysis, and Fourier transform
infrared spectrometry before and after reaction. An
Arrhenius kinetics model was introduced to calculate the
rheological activation energy of heavy oil from the viscosity–
temperature characteristics. Results show that the
two oil-soluble catalysts can crack part of heavy components
into light components, decrease the heteroatom
content, and achieve the transition of reaction mode from
oxygen addition to bond scission. The calculated rheological
activation energy of heavy oil from the fitted Arrhenius
model is consistent with physical properties of heavy oil
(oil viscosity and contents of heavy fractions). It is found
that the temperature, oil composition, and internal molecular
structures are the main factors affecting its flow
ability. Oil-soluble catalyst-assisted air injection or air
huff-n-puff injection is a promising in situ catalytic
upgrading method for improving heavy oil recovery.