It takes millions of years for crude oil to be formed, and the process requires the presence of a good and complete petroleum system that consists of:
– Mature source rock (an organic rich source rock with kerogen and bitumen where hydrocarbon liquids are generated),
– Migration pathway (where hydrocarbon liquids move from source to reservoir rocks),
– Reservoir rock (a rock having sufficient porosity and permeability to store and transmit fluids where hydrocarbon liquids accumulates),
– Trap (a configuration of rocks suitable for containing hydrocarbons and sealed by a relatively impermeable formation through which hydrocarbons will not migrate),
– Seal/Cap rock (an impermeable rock that acts as a barrier to further migration of hydrocarbon liquids),
Appropriate relative timing of formation of these elements and the processes of generation, migration and accumulation are necessary for hydrocarbons to accumulate and be preserved.
