Petroleum comes from many different substances, such as oil and natural gas, from which various products are derived, such as: gasoline, kerosene propane, fuel oil, lubricating oil, wax, and asphalt. These substances are mainly compounds of only two elements: carbon (C) and hydrogen (H). They are called, therefore: hydrocarbons.
The specific study of petroleum is referred to as petroleum geochemistry. Understanding petroleum geochemistry is critical in the exploration and development of petroleum.