The second step of petroleum formation is known as the Catagenesis. In this step the kerogen formed in the first step is kerogen is exposed to increasing temperatures and pressures, and is broken down thermally to form hydrocarbons (petroleum) (White, 2006).
It is important note that even though both petroleum and coal are fossil fuels and are nonrenewable, the raw materials and their formation processes are quite different (White, 2006). While petroleum is formed from algae and zooplanktons, coal is formed from higher terrestrial plants (these plants are rich in lignin and cellulose) (White, 2006).
Petroleum is normally found within the reservoir. For a reservoir to hold recoverable oil it must be porous and permeable, while at the same the reservoir must have seal or trap to prevent the accumulated oil from escaping (White, 2006). During extraction a well is normally drilled through the reservoir. Oil the flows from the reservoir to the drilled well from where it flows to surface under the influence of natural underground pressure. When the pressure is so low that the oil cannot flow to surface or the oil so thick that it cannot flow, natural gas or hot water may be pumped into the well to enhance flow (White, 2006).
Extraction of oil is normally associated with several cases of environmental degradation such as oil spills, and waste chemical run-offs oil producing companies among others (Moss, 2010). These cases of environmental degradation as a result of oil production have reported in Nigeria, Azerbaijan, Kazakhstan, Columbia and Ecuador among others (Moss, 2010). For example, oil extraction companies have brought down trees in the rain forest of Ecuador (Moss, 2010). It is estimated that these trees are being brought down at a rate of about 340,000 hectares per year (Moss, 2010).
Energy is mainly produced from petroleum through combustion. Oil may combusted to heat