Catalytic in situ upgrading of heavy and extra heavy crude oils Heavy oil pose difficulties in extraction and upgrading due to its high viscosity low API gravity high asphaltenes metals (V Ni) and heteroatoms (N S) they also incur large transport and refining costs. In situ catalytic upgrading produces and partially upgrades heavy oil and is attractive due to its reduced environmental footprint. A reservoir behaves like a reactor for in situ catalytic reactions which also decreases the investment required for upgrading