In situ catalytic upgrading of heavy oil decomposes viscous heavy oil underground through a series of complex chemical and physical reactions with the aid of an injected catalyst, and permits the resulting lighter components to flow to the producer under a normal pressure drive. By eliminating or substantially reducing the use of steam, which is prevalently used in current heavy oil productions worldwide and is a potent source of contamination concerns if not treated properly, in situ catalytic upgrading is intrinsically environmental-friendly and widely regarded as one of the promising techniques routes to decarbonize the oil industry. The present review provides a state-of-the-art summarization of the technologies of in situ catalytic upgrading and viscosity reduction in heavy oil from the aspects of catalyst selections, catalytic mechanisms, catalytic methods, and applications. The various types of widely used catalysts are compared and discussed in detail. Factors that impact the efficacy of the in situ upgrading of heavy oil are presented. The challenges and recommendations for future development are also furnished. This in-depth review is intended to give a well-rounded introduction to critical aspects on which the in situ catalytic application can shed light in the development of the world’s extra heavy oil reservoirs.

Numerical reservoir simulation, which includes the construction and operation of a model that performs similarly to a real-world reservoir, is an effective method for exploring complex reservoir issues. Due to the complexity of constructing reservoir environments for experiments, numerical simulation is a vital method for studying flow behavior under reservoir conditions. In this study, a black-oil modeling simulator was used to construct, simulate, and evaluate a conceptual hydrocarbon reservoir model. The model evolved by drilling two production wells and one injection well in two cases. The first case consisted of two horizontal production wells and one injection well, while the second consisted of two vertical production wells and an injection well. In total, 25 simulation runs were performed, and the results showed that horizontal wells perform better than vertical wells in terms of productivity, with a field oil production total of 1,930,000 m3. This is significantly higher than vertical wells, which have a field oil production total of 1,890,000 m3 after 1840 days. The field recovery factor for horizontal wells was 41% and for vertical wells it was 39%, both of which were less than 50%. This indicates that the reservoir’s sweeping efficiency was minimal. To enhance sweeping efficiency, the water injection rate and number of injection wells should be increased, as well as well patterns and locations remodeled. It was also shown that as reservoir thickness increased, horizontal and vertical well productivity increased. In order to boost horizontal well productivity and increase field oil recovery above 50%, the horizontal well length should be increased to take up a wider area of the reservoir portion. On the other hand, well length may have no impact on vertical well production efficiency.